Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 29246b5e51060717e19c0b092ddad5d07237c9be / . / docs / LangRef.html
blob: 949ffe6c29a9ceaa580fba9dd0eb29e5750e0732 [file] [log] [blame]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
10 <link rel="stylesheet" href="llvm.css" type="text/css">
11</head>
12
13<body>
14
15<div class="doc_title"> LLVM Language Reference Manual </div>
16<ol>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
Bill Wendling41a07852009-07-20 01:03:30 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a>
24 <ol>
Bill Wendlinge2753242009-07-20 02:41:50 +0000[diff] [blame]25 <li><a href="#linkage_private">'<tt>private</tt>' Linkage</a></li>
26 <li><a href="#linkage_linker_private">'<tt>linker_private</tt>' Linkage</a></li>
27 <li><a href="#linkage_internal">'<tt>internal</tt>' Linkage</a></li>
28 <li><a href="#linkage_available_externally">'<tt>available_externally</tt>' Linkage</a></li>
29 <li><a href="#linkage_linkonce">'<tt>linkonce</tt>' Linkage</a></li>
30 <li><a href="#linkage_common">'<tt>common</tt>' Linkage</a></li>
31 <li><a href="#linkage_weak">'<tt>weak</tt>' Linkage</a></li>
32 <li><a href="#linkage_appending">'<tt>appending</tt>' Linkage</a></li>
33 <li><a href="#linkage_externweak">'<tt>extern_weak</tt>' Linkage</a></li>
Chris Lattner0fee5c22009-10-10 18:26:06 +0000[diff] [blame]34 <li><a href="#linkage_linkonce_odr">'<tt>linkonce_odr</tt>' Linkage</a></li>
Bill Wendlinge2753242009-07-20 02:41:50 +0000[diff] [blame]35 <li><a href="#linkage_weak">'<tt>weak_odr</tt>' Linkage</a></li>
36 <li><a href="#linkage_external">'<tt>externally visible</tt>' Linkage</a></li>
37 <li><a href="#linkage_dllimport">'<tt>dllimport</tt>' Linkage</a></li>
38 <li><a href="#linkage_dllexport">'<tt>dllexport</tt>' Linkage</a></li>
Bill Wendling41a07852009-07-20 01:03:30 +0000[diff] [blame]39 </ol>
40 </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]41 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]42 <li><a href="#namedtypes">Named Types</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]43 <li><a href="#globalvars">Global Variables</a></li>
44 <li><a href="#functionstructure">Functions</a></li>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]45 <li><a href="#aliasstructure">Aliases</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]46 <li><a href="#paramattrs">Parameter Attributes</a></li>
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]47 <li><a href="#fnattrs">Function Attributes</a></li>
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]48 <li><a href="#gc">Garbage Collector Names</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]49 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
50 <li><a href="#datalayout">Data Layout</a></li>
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]51 <li><a href="#pointeraliasing">Pointer Aliasing Rules</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]52 </ol>
53 </li>
54 <li><a href="#typesystem">Type System</a>
55 <ol>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]56 <li><a href="#t_classifications">Type Classifications</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]57 <li><a href="#t_primitive">Primitive Types</a>
58 <ol>
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]59 <li><a href="#t_integer">Integer Type</a></li>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]60 <li><a href="#t_floating">Floating Point Types</a></li>
61 <li><a href="#t_void">Void Type</a></li>
62 <li><a href="#t_label">Label Type</a></li>
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]63 <li><a href="#t_metadata">Metadata Type</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]64 </ol>
65 </li>
66 <li><a href="#t_derived">Derived Types</a>
67 <ol>
68 <li><a href="#t_array">Array Type</a></li>
69 <li><a href="#t_function">Function Type</a></li>
70 <li><a href="#t_pointer">Pointer Type</a></li>
71 <li><a href="#t_struct">Structure Type</a></li>
72 <li><a href="#t_pstruct">Packed Structure Type</a></li>
73 <li><a href="#t_vector">Vector Type</a></li>
74 <li><a href="#t_opaque">Opaque Type</a></li>
75 </ol>
76 </li>
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]77 <li><a href="#t_uprefs">Type Up-references</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]78 </ol>
79 </li>
80 <li><a href="#constants">Constants</a>
81 <ol>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]82 <li><a href="#simpleconstants">Simple Constants</a></li>
Chris Lattner97063852009-02-28 18:32:25 +0000[diff] [blame]83 <li><a href="#complexconstants">Complex Constants</a></li>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]84 <li><a href="#globalconstants">Global Variable and Function Addresses</a></li>
85 <li><a href="#undefvalues">Undefined Values</a></li>
Chris Lattner29246b52009-10-27 21:19:13 +0000[diff] [blame^]86 <li><a href="#blockaddress">Addresses of Basic Blocks</a></li>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]87 <li><a href="#constantexprs">Constant Expressions</a></li>
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]88 <li><a href="#metadata">Embedded Metadata</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]89 </ol>
90 </li>
91 <li><a href="#othervalues">Other Values</a>
92 <ol>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]93 <li><a href="#inlineasm">Inline Assembler Expressions</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]94 </ol>
95 </li>
Chris Lattner75c24e02009-07-20 05:55:19 +0000[diff] [blame]96 <li><a href="#intrinsic_globals">Intrinsic Global Variables</a>
97 <ol>
98 <li><a href="#intg_used">The '<tt>llvm.used</tt>' Global Variable</a></li>
Chris Lattner1e0e0d12009-07-20 06:14:25 +0000[diff] [blame]99 <li><a href="#intg_compiler_used">The '<tt>llvm.compiler.used</tt>'
100 Global Variable</a></li>
Chris Lattner75c24e02009-07-20 05:55:19 +0000[diff] [blame]101 <li><a href="#intg_global_ctors">The '<tt>llvm.global_ctors</tt>'
102 Global Variable</a></li>
103 <li><a href="#intg_global_dtors">The '<tt>llvm.global_dtors</tt>'
104 Global Variable</a></li>
105 </ol>
106 </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]107 <li><a href="#instref">Instruction Reference</a>
108 <ol>
109 <li><a href="#terminators">Terminator Instructions</a>
110 <ol>
111 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
112 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
113 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
Chris Lattnere0787282009-10-27 19:13:16 +0000[diff] [blame]114 <li><a href="#i_indbr">'<tt>indbr</tt>' Instruction</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]115 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
116 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
117 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
118 </ol>
119 </li>
120 <li><a href="#binaryops">Binary Operations</a>
121 <ol>
122 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]123 <li><a href="#i_fadd">'<tt>fadd</tt>' Instruction</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]124 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]125 <li><a href="#i_fsub">'<tt>fsub</tt>' Instruction</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]126 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]127 <li><a href="#i_fmul">'<tt>fmul</tt>' Instruction</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]128 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
129 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
130 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
131 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
132 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
133 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
134 </ol>
135 </li>
136 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
137 <ol>
138 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
139 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
140 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
141 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
142 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
143 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
144 </ol>
145 </li>
146 <li><a href="#vectorops">Vector Operations</a>
147 <ol>
148 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
149 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
150 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
151 </ol>
152 </li>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]153 <li><a href="#aggregateops">Aggregate Operations</a>
154 <ol>
155 <li><a href="#i_extractvalue">'<tt>extractvalue</tt>' Instruction</a></li>
156 <li><a href="#i_insertvalue">'<tt>insertvalue</tt>' Instruction</a></li>
157 </ol>
158 </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]159 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
160 <ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]161 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
162 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
163 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
164 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
165 </ol>
166 </li>
167 <li><a href="#convertops">Conversion Operations</a>
168 <ol>
169 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
170 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
171 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
172 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
173 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
174 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
175 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
176 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
177 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
178 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
179 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
180 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
181 </ol>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]182 </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]183 <li><a href="#otherops">Other Operations</a>
184 <ol>
185 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
186 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
187 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
188 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
189 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
190 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
191 </ol>
192 </li>
193 </ol>
194 </li>
195 <li><a href="#intrinsics">Intrinsic Functions</a>
196 <ol>
197 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
198 <ol>
199 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
200 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
201 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
202 </ol>
203 </li>
204 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
205 <ol>
206 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
207 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
208 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
209 </ol>
210 </li>
211 <li><a href="#int_codegen">Code Generator Intrinsics</a>
212 <ol>
213 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
214 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
215 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
216 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
217 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
218 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
219 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
220 </ol>
221 </li>
222 <li><a href="#int_libc">Standard C Library Intrinsics</a>
223 <ol>
224 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
225 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
226 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
227 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
228 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]229 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
230 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
231 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]232 </ol>
233 </li>
234 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
235 <ol>
236 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
237 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
238 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
239 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]240 </ol>
241 </li>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]242 <li><a href="#int_overflow">Arithmetic with Overflow Intrinsics</a>
243 <ol>
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]244 <li><a href="#int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt> Intrinsics</a></li>
245 <li><a href="#int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt> Intrinsics</a></li>
246 <li><a href="#int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt> Intrinsics</a></li>
247 <li><a href="#int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt> Intrinsics</a></li>
248 <li><a href="#int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt> Intrinsics</a></li>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]249 <li><a href="#int_umul_overflow">'<tt>llvm.umul.with.overflow.*</tt> Intrinsics</a></li>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]250 </ol>
251 </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]252 <li><a href="#int_debugger">Debugger intrinsics</a></li>
253 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]254 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]255 <ol>
256 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]257 </ol>
258 </li>
Bill Wendling9127adb2008-11-18 22:10:53 +0000[diff] [blame]259 <li><a href="#int_atomics">Atomic intrinsics</a>
260 <ol>
261 <li><a href="#int_memory_barrier"><tt>llvm.memory_barrier</tt></a></li>
262 <li><a href="#int_atomic_cmp_swap"><tt>llvm.atomic.cmp.swap</tt></a></li>
263 <li><a href="#int_atomic_swap"><tt>llvm.atomic.swap</tt></a></li>
264 <li><a href="#int_atomic_load_add"><tt>llvm.atomic.load.add</tt></a></li>
265 <li><a href="#int_atomic_load_sub"><tt>llvm.atomic.load.sub</tt></a></li>
266 <li><a href="#int_atomic_load_and"><tt>llvm.atomic.load.and</tt></a></li>
267 <li><a href="#int_atomic_load_nand"><tt>llvm.atomic.load.nand</tt></a></li>
268 <li><a href="#int_atomic_load_or"><tt>llvm.atomic.load.or</tt></a></li>
269 <li><a href="#int_atomic_load_xor"><tt>llvm.atomic.load.xor</tt></a></li>
270 <li><a href="#int_atomic_load_max"><tt>llvm.atomic.load.max</tt></a></li>
271 <li><a href="#int_atomic_load_min"><tt>llvm.atomic.load.min</tt></a></li>
272 <li><a href="#int_atomic_load_umax"><tt>llvm.atomic.load.umax</tt></a></li>
273 <li><a href="#int_atomic_load_umin"><tt>llvm.atomic.load.umin</tt></a></li>
274 </ol>
275 </li>
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]276 <li><a href="#int_memorymarkers">Memory Use Markers</a>
277 <ol>
278 <li><a href="#int_lifetime_start"><tt>llvm.lifetime.start</tt></a></li>
279 <li><a href="#int_lifetime_end"><tt>llvm.lifetime.end</tt></a></li>
280 <li><a href="#int_invariant_start"><tt>llvm.invariant.start</tt></a></li>
281 <li><a href="#int_invariant_end"><tt>llvm.invariant.end</tt></a></li>
282 </ol>
283 </li>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]284 <li><a href="#int_general">General intrinsics</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]285 <ol>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]286 <li><a href="#int_var_annotation">
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]287 '<tt>llvm.var.annotation</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]288 <li><a href="#int_annotation">
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]289 '<tt>llvm.annotation.*</tt>' Intrinsic</a></li>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]290 <li><a href="#int_trap">
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]291 '<tt>llvm.trap</tt>' Intrinsic</a></li>
292 <li><a href="#int_stackprotector">
293 '<tt>llvm.stackprotector</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]294 </ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]295 </li>
296 </ol>
297 </li>
298</ol>
299
300<div class="doc_author">
301 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
302 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
303</div>
304
305<!-- *********************************************************************** -->
306<div class="doc_section"> <a name="abstract">Abstract </a></div>
307<!-- *********************************************************************** -->
308
309<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]310
311<p>This document is a reference manual for the LLVM assembly language. LLVM is
312 a Static Single Assignment (SSA) based representation that provides type
313 safety, low-level operations, flexibility, and the capability of representing
314 'all' high-level languages cleanly. It is the common code representation
315 used throughout all phases of the LLVM compilation strategy.</p>
316
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]317</div>
318
319<!-- *********************************************************************** -->
320<div class="doc_section"> <a name="introduction">Introduction</a> </div>
321<!-- *********************************************************************** -->
322
323<div class="doc_text">
324
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]325<p>The LLVM code representation is designed to be used in three different forms:
326 as an in-memory compiler IR, as an on-disk bitcode representation (suitable
327 for fast loading by a Just-In-Time compiler), and as a human readable
328 assembly language representation. This allows LLVM to provide a powerful
329 intermediate representation for efficient compiler transformations and
330 analysis, while providing a natural means to debug and visualize the
331 transformations. The three different forms of LLVM are all equivalent. This
332 document describes the human readable representation and notation.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]333
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]334<p>The LLVM representation aims to be light-weight and low-level while being
335 expressive, typed, and extensible at the same time. It aims to be a
336 "universal IR" of sorts, by being at a low enough level that high-level ideas
337 may be cleanly mapped to it (similar to how microprocessors are "universal
338 IR's", allowing many source languages to be mapped to them). By providing
339 type information, LLVM can be used as the target of optimizations: for
340 example, through pointer analysis, it can be proven that a C automatic
341 variable is never accessed outside of the current function... allowing it to
342 be promoted to a simple SSA value instead of a memory location.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]343
344</div>
345
346<!-- _______________________________________________________________________ -->
347<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
348
349<div class="doc_text">
350
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]351<p>It is important to note that this document describes 'well formed' LLVM
352 assembly language. There is a difference between what the parser accepts and
353 what is considered 'well formed'. For example, the following instruction is
354 syntactically okay, but not well formed:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]355
356<div class="doc_code">
357<pre>
358%x = <a href="#i_add">add</a> i32 1, %x
359</pre>
360</div>
361
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]362<p>...because the definition of <tt>%x</tt> does not dominate all of its
363 uses. The LLVM infrastructure provides a verification pass that may be used
364 to verify that an LLVM module is well formed. This pass is automatically run
365 by the parser after parsing input assembly and by the optimizer before it
366 outputs bitcode. The violations pointed out by the verifier pass indicate
367 bugs in transformation passes or input to the parser.</p>
368
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]369</div>
370
Chris Lattnera83fdc02007-10-03 17:34:29 +0000[diff] [blame]371<!-- Describe the typesetting conventions here. -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]372
373<!-- *********************************************************************** -->
374<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
375<!-- *********************************************************************** -->
376
377<div class="doc_text">
378
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]379<p>LLVM identifiers come in two basic types: global and local. Global
380 identifiers (functions, global variables) begin with the <tt>'@'</tt>
381 character. Local identifiers (register names, types) begin with
382 the <tt>'%'</tt> character. Additionally, there are three different formats
383 for identifiers, for different purposes:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]384
385<ol>
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]386 <li>Named values are represented as a string of characters with their prefix.
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]387 For example, <tt>%foo</tt>, <tt>@DivisionByZero</tt>,
388 <tt>%a.really.long.identifier</tt>. The actual regular expression used is
389 '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'. Identifiers which require
390 other characters in their names can be surrounded with quotes. Special
391 characters may be escaped using <tt>"\xx"</tt> where <tt>xx</tt> is the
392 ASCII code for the character in hexadecimal. In this way, any character
393 can be used in a name value, even quotes themselves.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]394
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]395 <li>Unnamed values are represented as an unsigned numeric value with their
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]396 prefix. For example, <tt>%12</tt>, <tt>@2</tt>, <tt>%44</tt>.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]397
398 <li>Constants, which are described in a <a href="#constants">section about
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]399 constants</a>, below.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]400</ol>
401
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]402<p>LLVM requires that values start with a prefix for two reasons: Compilers
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]403 don't need to worry about name clashes with reserved words, and the set of
404 reserved words may be expanded in the future without penalty. Additionally,
405 unnamed identifiers allow a compiler to quickly come up with a temporary
406 variable without having to avoid symbol table conflicts.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]407
408<p>Reserved words in LLVM are very similar to reserved words in other
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]409 languages. There are keywords for different opcodes
410 ('<tt><a href="#i_add">add</a></tt>',
411 '<tt><a href="#i_bitcast">bitcast</a></tt>',
412 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names
413 ('<tt><a href="#t_void">void</a></tt>',
414 '<tt><a href="#t_primitive">i32</a></tt>', etc...), and others. These
415 reserved words cannot conflict with variable names, because none of them
416 start with a prefix character (<tt>'%'</tt> or <tt>'@'</tt>).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]417
418<p>Here is an example of LLVM code to multiply the integer variable
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]419 '<tt>%X</tt>' by 8:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]420
421<p>The easy way:</p>
422
423<div class="doc_code">
424<pre>
425%result = <a href="#i_mul">mul</a> i32 %X, 8
426</pre>
427</div>
428
429<p>After strength reduction:</p>
430
431<div class="doc_code">
432<pre>
433%result = <a href="#i_shl">shl</a> i32 %X, i8 3
434</pre>
435</div>
436
437<p>And the hard way:</p>
438
439<div class="doc_code">
440<pre>
441<a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
442<a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
443%result = <a href="#i_add">add</a> i32 %1, %1
444</pre>
445</div>
446
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]447<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several important
448 lexical features of LLVM:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]449
450<ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]451 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]452 line.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]453
454 <li>Unnamed temporaries are created when the result of a computation is not
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]455 assigned to a named value.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]456
457 <li>Unnamed temporaries are numbered sequentially</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]458</ol>
459
460<p>...and it also shows a convention that we follow in this document. When
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]461 demonstrating instructions, we will follow an instruction with a comment that
462 defines the type and name of value produced. Comments are shown in italic
463 text.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]464
465</div>
466
467<!-- *********************************************************************** -->
468<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
469<!-- *********************************************************************** -->
470
471<!-- ======================================================================= -->
472<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
473</div>
474
475<div class="doc_text">
476
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]477<p>LLVM programs are composed of "Module"s, each of which is a translation unit
478 of the input programs. Each module consists of functions, global variables,
479 and symbol table entries. Modules may be combined together with the LLVM
480 linker, which merges function (and global variable) definitions, resolves
481 forward declarations, and merges symbol table entries. Here is an example of
482 the "hello world" module:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]483
484<div class="doc_code">
485<pre><i>; Declare the string constant as a global constant...</i>
486<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
487 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
488
489<i>; External declaration of the puts function</i>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]490<a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]491
492<i>; Definition of main function</i>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]493define i32 @main() { <i>; i32()* </i>
Dan Gohman01852382009-01-04 23:44:43 +0000[diff] [blame]494 <i>; Convert [13 x i8]* to i8 *...</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]495 %cast210 = <a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]496 href="#i_getelementptr">getelementptr</a> [13 x i8]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]497
498 <i>; Call puts function to write out the string to stdout...</i>
499 <a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]500 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]501 <a
502 href="#i_ret">ret</a> i32 0<br>}<br>
503</pre>
504</div>
505
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]506<p>This example is made up of a <a href="#globalvars">global variable</a> named
507 "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>" function, and
508 a <a href="#functionstructure">function definition</a> for
509 "<tt>main</tt>".</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]510
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]511<p>In general, a module is made up of a list of global values, where both
512 functions and global variables are global values. Global values are
513 represented by a pointer to a memory location (in this case, a pointer to an
514 array of char, and a pointer to a function), and have one of the
515 following <a href="#linkage">linkage types</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]516
517</div>
518
519<!-- ======================================================================= -->
520<div class="doc_subsection">
521 <a name="linkage">Linkage Types</a>
522</div>
523
524<div class="doc_text">
525
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]526<p>All Global Variables and Functions have one of the following types of
527 linkage:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]528
529<dl>
Rafael Espindolaa168fc92009-01-15 20:18:42 +0000[diff] [blame]530 <dt><tt><b><a name="linkage_private">private</a></b></tt>: </dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]531 <dd>Global values with private linkage are only directly accessible by objects
532 in the current module. In particular, linking code into a module with an
533 private global value may cause the private to be renamed as necessary to
534 avoid collisions. Because the symbol is private to the module, all
535 references can be updated. This doesn't show up in any symbol table in the
536 object file.</dd>
Rafael Espindolaa168fc92009-01-15 20:18:42 +0000[diff] [blame]537
Bill Wendling41a07852009-07-20 01:03:30 +0000[diff] [blame]538 <dt><tt><b><a name="linkage_linker_private">linker_private</a></b></tt>: </dt>
Bill Wendling41a07852009-07-20 01:03:30 +0000[diff] [blame]539 <dd>Similar to private, but the symbol is passed through the assembler and
Chris Lattner06c1ecc2009-08-24 04:32:16 +0000[diff] [blame]540 removed by the linker after evaluation. Note that (unlike private
541 symbols) linker_private symbols are subject to coalescing by the linker:
542 weak symbols get merged and redefinitions are rejected. However, unlike
543 normal strong symbols, they are removed by the linker from the final
544 linked image (executable or dynamic library).</dd>
Bill Wendling41a07852009-07-20 01:03:30 +0000[diff] [blame]545
Dale Johannesen96e7e092008-05-23 23:13:41 +0000[diff] [blame]546 <dt><tt><b><a name="linkage_internal">internal</a></b></tt>: </dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]547 <dd>Similar to private, but the value shows as a local symbol
548 (<tt>STB_LOCAL</tt> in the case of ELF) in the object file. This
549 corresponds to the notion of the '<tt>static</tt>' keyword in C.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]550
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]551 <dt><tt><b><a name="linkage_available_externally">available_externally</a></b></tt>: </dt>
Chris Lattner68433442009-04-13 05:44:34 +0000[diff] [blame]552 <dd>Globals with "<tt>available_externally</tt>" linkage are never emitted
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]553 into the object file corresponding to the LLVM module. They exist to
554 allow inlining and other optimizations to take place given knowledge of
555 the definition of the global, which is known to be somewhere outside the
556 module. Globals with <tt>available_externally</tt> linkage are allowed to
557 be discarded at will, and are otherwise the same as <tt>linkonce_odr</tt>.
558 This linkage type is only allowed on definitions, not declarations.</dd>
Chris Lattner68433442009-04-13 05:44:34 +0000[diff] [blame]559
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]560 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]561 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]562 the same name when linkage occurs. This is typically used to implement
563 inline functions, templates, or other code which must be generated in each
564 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
565 allowed to be discarded.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]566
567 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattner7215c7f2009-08-05 05:21:07 +0000[diff] [blame]568 <dd>"<tt>weak</tt>" linkage has the same merging semantics as
569 <tt>linkonce</tt> linkage, except that unreferenced globals with
570 <tt>weak</tt> linkage may not be discarded. This is used for globals that
571 are declared "weak" in C source code.</dd>
572
573 <dt><tt><b><a name="linkage_common">common</a></b></tt>: </dt>
574 <dd>"<tt>common</tt>" linkage is most similar to "<tt>weak</tt>" linkage, but
575 they are used for tentative definitions in C, such as "<tt>int X;</tt>" at
576 global scope.
577 Symbols with "<tt>common</tt>" linkage are merged in the same way as
578 <tt>weak symbols</tt>, and they may not be deleted if unreferenced.
Chris Lattner83c4a712009-08-05 05:41:44 +0000[diff] [blame]579 <tt>common</tt> symbols may not have an explicit section,
580 must have a zero initializer, and may not be marked '<a
581 href="#globalvars"><tt>constant</tt></a>'. Functions and aliases may not
582 have common linkage.</dd>
Chris Lattner7215c7f2009-08-05 05:21:07 +0000[diff] [blame]583
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]584
585 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]586 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]587 pointer to array type. When two global variables with appending linkage
588 are linked together, the two global arrays are appended together. This is
589 the LLVM, typesafe, equivalent of having the system linker append together
590 "sections" with identical names when .o files are linked.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]591
592 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]593 <dd>The semantics of this linkage follow the ELF object file model: the symbol
594 is weak until linked, if not linked, the symbol becomes null instead of
595 being an undefined reference.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]596
Chris Lattner0fee5c22009-10-10 18:26:06 +0000[diff] [blame]597 <dt><tt><b><a name="linkage_linkonce_odr">linkonce_odr</a></b></tt>: </dt>
598 <dt><tt><b><a name="linkage_weak_odr">weak_odr</a></b></tt>: </dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]599 <dd>Some languages allow differing globals to be merged, such as two functions
600 with different semantics. Other languages, such as <tt>C++</tt>, ensure
601 that only equivalent globals are ever merged (the "one definition rule" -
602 "ODR"). Such languages can use the <tt>linkonce_odr</tt>
603 and <tt>weak_odr</tt> linkage types to indicate that the global will only
604 be merged with equivalent globals. These linkage types are otherwise the
605 same as their non-<tt>odr</tt> versions.</dd>
Duncan Sands19d161f2009-03-07 15:45:40 +0000[diff] [blame]606
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]607 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]608 <dd>If none of the above identifiers are used, the global is externally
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]609 visible, meaning that it participates in linkage and can be used to
610 resolve external symbol references.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]611</dl>
612
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]613<p>The next two types of linkage are targeted for Microsoft Windows platform
614 only. They are designed to support importing (exporting) symbols from (to)
615 DLLs (Dynamic Link Libraries).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]616
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]617<dl>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]618 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]619 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]620 or variable via a global pointer to a pointer that is set up by the DLL
621 exporting the symbol. On Microsoft Windows targets, the pointer name is
622 formed by combining <code>__imp_</code> and the function or variable
623 name.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]624
625 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]626 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]627 pointer to a pointer in a DLL, so that it can be referenced with the
628 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
629 name is formed by combining <code>__imp_</code> and the function or
630 variable name.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]631</dl>
632
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]633<p>For example, since the "<tt>.LC0</tt>" variable is defined to be internal, if
634 another module defined a "<tt>.LC0</tt>" variable and was linked with this
635 one, one of the two would be renamed, preventing a collision. Since
636 "<tt>main</tt>" and "<tt>puts</tt>" are external (i.e., lacking any linkage
637 declarations), they are accessible outside of the current module.</p>
638
639<p>It is illegal for a function <i>declaration</i> to have any linkage type
640 other than "externally visible", <tt>dllimport</tt>
641 or <tt>extern_weak</tt>.</p>
642
Duncan Sands19d161f2009-03-07 15:45:40 +0000[diff] [blame]643<p>Aliases can have only <tt>external</tt>, <tt>internal</tt>, <tt>weak</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]644 or <tt>weak_odr</tt> linkages.</p>
645
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]646</div>
647
648<!-- ======================================================================= -->
649<div class="doc_subsection">
650 <a name="callingconv">Calling Conventions</a>
651</div>
652
653<div class="doc_text">
654
655<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]656 and <a href="#i_invoke">invokes</a> can all have an optional calling
657 convention specified for the call. The calling convention of any pair of
658 dynamic caller/callee must match, or the behavior of the program is
659 undefined. The following calling conventions are supported by LLVM, and more
660 may be added in the future:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]661
662<dl>
663 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]664 <dd>This calling convention (the default if no other calling convention is
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]665 specified) matches the target C calling conventions. This calling
666 convention supports varargs function calls and tolerates some mismatch in
667 the declared prototype and implemented declaration of the function (as
668 does normal C).</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]669
670 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]671 <dd>This calling convention attempts to make calls as fast as possible
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]672 (e.g. by passing things in registers). This calling convention allows the
673 target to use whatever tricks it wants to produce fast code for the
674 target, without having to conform to an externally specified ABI
675 (Application Binary Interface). Implementations of this convention should
676 allow arbitrary <a href="CodeGenerator.html#tailcallopt">tail call
677 optimization</a> to be supported. This calling convention does not
678 support varargs and requires the prototype of all callees to exactly match
679 the prototype of the function definition.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]680
681 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]682 <dd>This calling convention attempts to make code in the caller as efficient
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]683 as possible under the assumption that the call is not commonly executed.
684 As such, these calls often preserve all registers so that the call does
685 not break any live ranges in the caller side. This calling convention
686 does not support varargs and requires the prototype of all callees to
687 exactly match the prototype of the function definition.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]688
689 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]690 <dd>Any calling convention may be specified by number, allowing
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]691 target-specific calling conventions to be used. Target specific calling
692 conventions start at 64.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]693</dl>
694
695<p>More calling conventions can be added/defined on an as-needed basis, to
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]696 support Pascal conventions or any other well-known target-independent
697 convention.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]698
699</div>
700
701<!-- ======================================================================= -->
702<div class="doc_subsection">
703 <a name="visibility">Visibility Styles</a>
704</div>
705
706<div class="doc_text">
707
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]708<p>All Global Variables and Functions have one of the following visibility
709 styles:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]710
711<dl>
712 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
Chris Lattner96451482008-08-05 18:29:16 +0000[diff] [blame]713 <dd>On targets that use the ELF object file format, default visibility means
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]714 that the declaration is visible to other modules and, in shared libraries,
715 means that the declared entity may be overridden. On Darwin, default
716 visibility means that the declaration is visible to other modules. Default
717 visibility corresponds to "external linkage" in the language.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]718
719 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]720 <dd>Two declarations of an object with hidden visibility refer to the same
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]721 object if they are in the same shared object. Usually, hidden visibility
722 indicates that the symbol will not be placed into the dynamic symbol
723 table, so no other module (executable or shared library) can reference it
724 directly.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]725
726 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]727 <dd>On ELF, protected visibility indicates that the symbol will be placed in
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]728 the dynamic symbol table, but that references within the defining module
729 will bind to the local symbol. That is, the symbol cannot be overridden by
730 another module.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]731</dl>
732
733</div>
734
735<!-- ======================================================================= -->
736<div class="doc_subsection">
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]737 <a name="namedtypes">Named Types</a>
738</div>
739
740<div class="doc_text">
741
742<p>LLVM IR allows you to specify name aliases for certain types. This can make
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]743 it easier to read the IR and make the IR more condensed (particularly when
744 recursive types are involved). An example of a name specification is:</p>
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]745
746<div class="doc_code">
747<pre>
748%mytype = type { %mytype*, i32 }
749</pre>
750</div>
751
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]752<p>You may give a name to any <a href="#typesystem">type</a> except
753 "<a href="t_void">void</a>". Type name aliases may be used anywhere a type
754 is expected with the syntax "%mytype".</p>
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]755
756<p>Note that type names are aliases for the structural type that they indicate,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]757 and that you can therefore specify multiple names for the same type. This
758 often leads to confusing behavior when dumping out a .ll file. Since LLVM IR
759 uses structural typing, the name is not part of the type. When printing out
760 LLVM IR, the printer will pick <em>one name</em> to render all types of a
761 particular shape. This means that if you have code where two different
762 source types end up having the same LLVM type, that the dumper will sometimes
763 print the "wrong" or unexpected type. This is an important design point and
764 isn't going to change.</p>
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]765
766</div>
767
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]768<!-- ======================================================================= -->
769<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]770 <a name="globalvars">Global Variables</a>
771</div>
772
773<div class="doc_text">
774
775<p>Global variables define regions of memory allocated at compilation time
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]776 instead of run-time. Global variables may optionally be initialized, may
777 have an explicit section to be placed in, and may have an optional explicit
778 alignment specified. A variable may be defined as "thread_local", which
779 means that it will not be shared by threads (each thread will have a
780 separated copy of the variable). A variable may be defined as a global
781 "constant," which indicates that the contents of the variable
782 will <b>never</b> be modified (enabling better optimization, allowing the
783 global data to be placed in the read-only section of an executable, etc).
784 Note that variables that need runtime initialization cannot be marked
785 "constant" as there is a store to the variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]786
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]787<p>LLVM explicitly allows <em>declarations</em> of global variables to be marked
788 constant, even if the final definition of the global is not. This capability
789 can be used to enable slightly better optimization of the program, but
790 requires the language definition to guarantee that optimizations based on the
791 'constantness' are valid for the translation units that do not include the
792 definition.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]793
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]794<p>As SSA values, global variables define pointer values that are in scope
795 (i.e. they dominate) all basic blocks in the program. Global variables
796 always define a pointer to their "content" type because they describe a
797 region of memory, and all memory objects in LLVM are accessed through
798 pointers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]799
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]800<p>A global variable may be declared to reside in a target-specific numbered
801 address space. For targets that support them, address spaces may affect how
802 optimizations are performed and/or what target instructions are used to
803 access the variable. The default address space is zero. The address space
804 qualifier must precede any other attributes.</p>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]805
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]806<p>LLVM allows an explicit section to be specified for globals. If the target
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]807 supports it, it will emit globals to the section specified.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]808
809<p>An explicit alignment may be specified for a global. If not present, or if
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]810 the alignment is set to zero, the alignment of the global is set by the
811 target to whatever it feels convenient. If an explicit alignment is
812 specified, the global is forced to have at least that much alignment. All
813 alignments must be a power of 2.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]814
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]815<p>For example, the following defines a global in a numbered address space with
816 an initializer, section, and alignment:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]817
818<div class="doc_code">
819<pre>
Dan Gohman21ef02c2009-01-11 00:40:00 +0000[diff] [blame]820@G = addrspace(5) constant float 1.0, section "foo", align 4
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]821</pre>
822</div>
823
824</div>
825
826
827<!-- ======================================================================= -->
828<div class="doc_subsection">
829 <a name="functionstructure">Functions</a>
830</div>
831
832<div class="doc_text">
833
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]834<p>LLVM function definitions consist of the "<tt>define</tt>" keyord, an
835 optional <a href="#linkage">linkage type</a>, an optional
836 <a href="#visibility">visibility style</a>, an optional
837 <a href="#callingconv">calling convention</a>, a return type, an optional
838 <a href="#paramattrs">parameter attribute</a> for the return type, a function
839 name, a (possibly empty) argument list (each with optional
840 <a href="#paramattrs">parameter attributes</a>), optional
841 <a href="#fnattrs">function attributes</a>, an optional section, an optional
842 alignment, an optional <a href="#gc">garbage collector name</a>, an opening
843 curly brace, a list of basic blocks, and a closing curly brace.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]844
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]845<p>LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
846 optional <a href="#linkage">linkage type</a>, an optional
847 <a href="#visibility">visibility style</a>, an optional
848 <a href="#callingconv">calling convention</a>, a return type, an optional
849 <a href="#paramattrs">parameter attribute</a> for the return type, a function
850 name, a possibly empty list of arguments, an optional alignment, and an
851 optional <a href="#gc">garbage collector name</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]852
Chris Lattner96451482008-08-05 18:29:16 +0000[diff] [blame]853<p>A function definition contains a list of basic blocks, forming the CFG
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]854 (Control Flow Graph) for the function. Each basic block may optionally start
855 with a label (giving the basic block a symbol table entry), contains a list
856 of instructions, and ends with a <a href="#terminators">terminator</a>
857 instruction (such as a branch or function return).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]858
859<p>The first basic block in a function is special in two ways: it is immediately
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]860 executed on entrance to the function, and it is not allowed to have
861 predecessor basic blocks (i.e. there can not be any branches to the entry
862 block of a function). Because the block can have no predecessors, it also
863 cannot have any <a href="#i_phi">PHI nodes</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]864
865<p>LLVM allows an explicit section to be specified for functions. If the target
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]866 supports it, it will emit functions to the section specified.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]867
868<p>An explicit alignment may be specified for a function. If not present, or if
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]869 the alignment is set to zero, the alignment of the function is set by the
870 target to whatever it feels convenient. If an explicit alignment is
871 specified, the function is forced to have at least that much alignment. All
872 alignments must be a power of 2.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]873
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]874<h5>Syntax:</h5>
Devang Pateld0bfcc72008-10-07 17:48:33 +0000[diff] [blame]875<div class="doc_code">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]876<pre>
Chris Lattner1e5c5cd02008-10-13 16:55:18 +0000[diff] [blame]877define [<a href="#linkage">linkage</a>] [<a href="#visibility">visibility</a>]
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]878 [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>]
879 &lt;ResultType&gt; @&lt;FunctionName&gt; ([argument list])
880 [<a href="#fnattrs">fn Attrs</a>] [section "name"] [align N]
881 [<a href="#gc">gc</a>] { ... }
882</pre>
Devang Pateld0bfcc72008-10-07 17:48:33 +0000[diff] [blame]883</div>
884
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]885</div>
886
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]887<!-- ======================================================================= -->
888<div class="doc_subsection">
889 <a name="aliasstructure">Aliases</a>
890</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]891
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]892<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]893
894<p>Aliases act as "second name" for the aliasee value (which can be either
895 function, global variable, another alias or bitcast of global value). Aliases
896 may have an optional <a href="#linkage">linkage type</a>, and an
897 optional <a href="#visibility">visibility style</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]898
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]899<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]900<div class="doc_code">
901<pre>
Duncan Sandsd7bfabf2008-09-12 20:48:21 +0000[diff] [blame]902@&lt;Name&gt; = alias [Linkage] [Visibility] &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]903</pre>
904</div>
905
906</div>
907
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]908<!-- ======================================================================= -->
909<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]910
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]911<div class="doc_text">
912
913<p>The return type and each parameter of a function type may have a set of
914 <i>parameter attributes</i> associated with them. Parameter attributes are
915 used to communicate additional information about the result or parameters of
916 a function. Parameter attributes are considered to be part of the function,
917 not of the function type, so functions with different parameter attributes
918 can have the same function type.</p>
919
920<p>Parameter attributes are simple keywords that follow the type specified. If
921 multiple parameter attributes are needed, they are space separated. For
922 example:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]923
924<div class="doc_code">
925<pre>
Nick Lewycky3022a742009-02-15 23:06:14 +0000[diff] [blame]926declare i32 @printf(i8* noalias nocapture, ...)
Chris Lattnerf33b8452008-10-04 18:33:34 +0000[diff] [blame]927declare i32 @atoi(i8 zeroext)
928declare signext i8 @returns_signed_char()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]929</pre>
930</div>
931
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]932<p>Note that any attributes for the function result (<tt>nounwind</tt>,
933 <tt>readonly</tt>) come immediately after the argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]934
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]935<p>Currently, only the following parameter attributes are defined:</p>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]936
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]937<dl>
938 <dt><tt>zeroext</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]939 <dd>This indicates to the code generator that the parameter or return value
940 should be zero-extended to a 32-bit value by the caller (for a parameter)
941 or the callee (for a return value).</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]942
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]943 <dt><tt>signext</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]944 <dd>This indicates to the code generator that the parameter or return value
945 should be sign-extended to a 32-bit value by the caller (for a parameter)
946 or the callee (for a return value).</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]947
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]948 <dt><tt>inreg</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]949 <dd>This indicates that this parameter or return value should be treated in a
950 special target-dependent fashion during while emitting code for a function
951 call or return (usually, by putting it in a register as opposed to memory,
952 though some targets use it to distinguish between two different kinds of
953 registers). Use of this attribute is target-specific.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]954
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]955 <dt><tt><a name="byval">byval</a></tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]956 <dd>This indicates that the pointer parameter should really be passed by value
957 to the function. The attribute implies that a hidden copy of the pointee
958 is made between the caller and the callee, so the callee is unable to
959 modify the value in the callee. This attribute is only valid on LLVM
960 pointer arguments. It is generally used to pass structs and arrays by
961 value, but is also valid on pointers to scalars. The copy is considered
962 to belong to the caller not the callee (for example,
963 <tt><a href="#readonly">readonly</a></tt> functions should not write to
964 <tt>byval</tt> parameters). This is not a valid attribute for return
965 values. The byval attribute also supports specifying an alignment with
966 the align attribute. This has a target-specific effect on the code
967 generator that usually indicates a desired alignment for the synthesized
968 stack slot.</dd>
969
970 <dt><tt>sret</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]971 <dd>This indicates that the pointer parameter specifies the address of a
972 structure that is the return value of the function in the source program.
973 This pointer must be guaranteed by the caller to be valid: loads and
974 stores to the structure may be assumed by the callee to not to trap. This
975 may only be applied to the first parameter. This is not a valid attribute
976 for return values. </dd>
977
978 <dt><tt>noalias</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]979 <dd>This indicates that the pointer does not alias any global or any other
980 parameter. The caller is responsible for ensuring that this is the
981 case. On a function return value, <tt>noalias</tt> additionally indicates
982 that the pointer does not alias any other pointers visible to the
983 caller. For further details, please see the discussion of the NoAlias
984 response in
985 <a href="http://llvm.org/docs/AliasAnalysis.html#MustMayNo">alias
986 analysis</a>.</dd>
987
988 <dt><tt>nocapture</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]989 <dd>This indicates that the callee does not make any copies of the pointer
990 that outlive the callee itself. This is not a valid attribute for return
991 values.</dd>
992
993 <dt><tt>nest</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]994 <dd>This indicates that the pointer parameter can be excised using the
995 <a href="#int_trampoline">trampoline intrinsics</a>. This is not a valid
996 attribute for return values.</dd>
997</dl>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]998
999</div>
1000
1001<!-- ======================================================================= -->
1002<div class="doc_subsection">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]1003 <a name="gc">Garbage Collector Names</a>
1004</div>
1005
1006<div class="doc_text">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]1007
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1008<p>Each function may specify a garbage collector name, which is simply a
1009 string:</p>
1010
1011<div class="doc_code">
1012<pre>
1013define void @f() gc "name" { ...
1014</pre>
1015</div>
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]1016
1017<p>The compiler declares the supported values of <i>name</i>. Specifying a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1018 collector which will cause the compiler to alter its output in order to
1019 support the named garbage collection algorithm.</p>
1020
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]1021</div>
1022
1023<!-- ======================================================================= -->
1024<div class="doc_subsection">
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]1025 <a name="fnattrs">Function Attributes</a>
Devang Pateld468f1c2008-09-04 23:05:13 +0000[diff] [blame]1026</div>
1027
1028<div class="doc_text">
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]1029
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1030<p>Function attributes are set to communicate additional information about a
1031 function. Function attributes are considered to be part of the function, not
1032 of the function type, so functions with different parameter attributes can
1033 have the same function type.</p>
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]1034
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1035<p>Function attributes are simple keywords that follow the type specified. If
1036 multiple attributes are needed, they are space separated. For example:</p>
Devang Pateld468f1c2008-09-04 23:05:13 +0000[diff] [blame]1037
1038<div class="doc_code">
Bill Wendling74d3eac2008-09-07 10:26:33 +0000[diff] [blame]1039<pre>
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]1040define void @f() noinline { ... }
1041define void @f() alwaysinline { ... }
1042define void @f() alwaysinline optsize { ... }
1043define void @f() optsize
Bill Wendling74d3eac2008-09-07 10:26:33 +0000[diff] [blame]1044</pre>
Devang Pateld468f1c2008-09-04 23:05:13 +0000[diff] [blame]1045</div>
1046
Bill Wendling74d3eac2008-09-07 10:26:33 +0000[diff] [blame]1047<dl>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1048 <dt><tt>alwaysinline</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1049 <dd>This attribute indicates that the inliner should attempt to inline this
1050 function into callers whenever possible, ignoring any active inlining size
1051 threshold for this caller.</dd>
Bill Wendling74d3eac2008-09-07 10:26:33 +0000[diff] [blame]1052
Dale Johannesen7fd6b0f2009-08-26 01:08:21 +0000[diff] [blame]1053 <dt><tt>inlinehint</tt></dt>
1054 <dd>This attribute indicates that the source code contained a hint that inlining
1055 this function is desirable (such as the "inline" keyword in C/C++). It
1056 is just a hint; it imposes no requirements on the inliner.</dd>
1057
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1058 <dt><tt>noinline</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1059 <dd>This attribute indicates that the inliner should never inline this
1060 function in any situation. This attribute may not be used together with
1061 the <tt>alwaysinline</tt> attribute.</dd>
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]1062
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1063 <dt><tt>optsize</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1064 <dd>This attribute suggests that optimization passes and code generator passes
1065 make choices that keep the code size of this function low, and otherwise
1066 do optimizations specifically to reduce code size.</dd>
Devang Patel008cd3e2008-09-26 23:51:19 +0000[diff] [blame]1067
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1068 <dt><tt>noreturn</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1069 <dd>This function attribute indicates that the function never returns
1070 normally. This produces undefined behavior at runtime if the function
1071 ever does dynamically return.</dd>
Bill Wendlingdfaabba2008-11-13 01:02:51 +0000[diff] [blame]1072
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1073 <dt><tt>nounwind</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1074 <dd>This function attribute indicates that the function never returns with an
1075 unwind or exceptional control flow. If the function does unwind, its
1076 runtime behavior is undefined.</dd>
Bill Wendlingbe9ec3f2008-11-26 19:07:40 +0000[diff] [blame]1077
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1078 <dt><tt>readnone</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1079 <dd>This attribute indicates that the function computes its result (or decides
1080 to unwind an exception) based strictly on its arguments, without
1081 dereferencing any pointer arguments or otherwise accessing any mutable
1082 state (e.g. memory, control registers, etc) visible to caller functions.
1083 It does not write through any pointer arguments
1084 (including <tt><a href="#byval">byval</a></tt> arguments) and never
1085 changes any state visible to callers. This means that it cannot unwind
1086 exceptions by calling the <tt>C++</tt> exception throwing methods, but
1087 could use the <tt>unwind</tt> instruction.</dd>
Devang Patela2f9f412009-06-12 19:45:19 +0000[diff] [blame]1088
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1089 <dt><tt><a name="readonly">readonly</a></tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1090 <dd>This attribute indicates that the function does not write through any
1091 pointer arguments (including <tt><a href="#byval">byval</a></tt>
1092 arguments) or otherwise modify any state (e.g. memory, control registers,
1093 etc) visible to caller functions. It may dereference pointer arguments
1094 and read state that may be set in the caller. A readonly function always
1095 returns the same value (or unwinds an exception identically) when called
1096 with the same set of arguments and global state. It cannot unwind an
1097 exception by calling the <tt>C++</tt> exception throwing methods, but may
1098 use the <tt>unwind</tt> instruction.</dd>
Anton Korobeynikovedd7d112009-07-17 18:07:26 +0000[diff] [blame]1099
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1100 <dt><tt><a name="ssp">ssp</a></tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1101 <dd>This attribute indicates that the function should emit a stack smashing
1102 protector. It is in the form of a "canary"&mdash;a random value placed on
1103 the stack before the local variables that's checked upon return from the
1104 function to see if it has been overwritten. A heuristic is used to
1105 determine if a function needs stack protectors or not.<br>
1106<br>
1107 If a function that has an <tt>ssp</tt> attribute is inlined into a
1108 function that doesn't have an <tt>ssp</tt> attribute, then the resulting
1109 function will have an <tt>ssp</tt> attribute.</dd>
1110
1111 <dt><tt>sspreq</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1112 <dd>This attribute indicates that the function should <em>always</em> emit a
1113 stack smashing protector. This overrides
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1114 the <tt><a href="#ssp">ssp</a></tt> function attribute.<br>
1115<br>
1116 If a function that has an <tt>sspreq</tt> attribute is inlined into a
1117 function that doesn't have an <tt>sspreq</tt> attribute or which has
1118 an <tt>ssp</tt> attribute, then the resulting function will have
1119 an <tt>sspreq</tt> attribute.</dd>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1120
1121 <dt><tt>noredzone</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1122 <dd>This attribute indicates that the code generator should not use a red
1123 zone, even if the target-specific ABI normally permits it.</dd>
1124
1125 <dt><tt>noimplicitfloat</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1126 <dd>This attributes disables implicit floating point instructions.</dd>
1127
1128 <dt><tt>naked</tt></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1129 <dd>This attribute disables prologue / epilogue emission for the function.
1130 This can have very system-specific consequences.</dd>
Bill Wendling74d3eac2008-09-07 10:26:33 +0000[diff] [blame]1131</dl>
1132
Devang Pateld468f1c2008-09-04 23:05:13 +0000[diff] [blame]1133</div>
1134
1135<!-- ======================================================================= -->
1136<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1137 <a name="moduleasm">Module-Level Inline Assembly</a>
1138</div>
1139
1140<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1141
1142<p>Modules may contain "module-level inline asm" blocks, which corresponds to
1143 the GCC "file scope inline asm" blocks. These blocks are internally
1144 concatenated by LLVM and treated as a single unit, but may be separated in
1145 the <tt>.ll</tt> file if desired. The syntax is very simple:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1146
1147<div class="doc_code">
1148<pre>
1149module asm "inline asm code goes here"
1150module asm "more can go here"
1151</pre>
1152</div>
1153
1154<p>The strings can contain any character by escaping non-printable characters.
1155 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1156 for the number.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1157
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1158<p>The inline asm code is simply printed to the machine code .s file when
1159 assembly code is generated.</p>
1160
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1161</div>
1162
1163<!-- ======================================================================= -->
1164<div class="doc_subsection">
1165 <a name="datalayout">Data Layout</a>
1166</div>
1167
1168<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1169
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1170<p>A module may specify a target specific data layout string that specifies how
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1171 data is to be laid out in memory. The syntax for the data layout is
1172 simply:</p>
1173
1174<div class="doc_code">
1175<pre>
1176target datalayout = "<i>layout specification</i>"
1177</pre>
1178</div>
1179
1180<p>The <i>layout specification</i> consists of a list of specifications
1181 separated by the minus sign character ('-'). Each specification starts with
1182 a letter and may include other information after the letter to define some
1183 aspect of the data layout. The specifications accepted are as follows:</p>
1184
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1185<dl>
1186 <dt><tt>E</tt></dt>
1187 <dd>Specifies that the target lays out data in big-endian form. That is, the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1188 bits with the most significance have the lowest address location.</dd>
1189
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1190 <dt><tt>e</tt></dt>
Chris Lattner96451482008-08-05 18:29:16 +0000[diff] [blame]1191 <dd>Specifies that the target lays out data in little-endian form. That is,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1192 the bits with the least significance have the lowest address
1193 location.</dd>
1194
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1195 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1196 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1197 <i>preferred</i> alignments. All sizes are in bits. Specifying
1198 the <i>pref</i> alignment is optional. If omitted, the
1199 preceding <tt>:</tt> should be omitted too.</dd>
1200
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1201 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1202 <dd>This specifies the alignment for an integer type of a given bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1203 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
1204
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1205 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1206 <dd>This specifies the alignment for a vector type of a given bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1207 <i>size</i>.</dd>
1208
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1209 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1210 <dd>This specifies the alignment for a floating point type of a given bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1211 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
1212 (double).</dd>
1213
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1214 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1215 <dd>This specifies the alignment for an aggregate type of a given bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1216 <i>size</i>.</dd>
1217
Daniel Dunbard88a97b2009-06-08 22:17:53 +0000[diff] [blame]1218 <dt><tt>s<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1219 <dd>This specifies the alignment for a stack object of a given bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1220 <i>size</i>.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1221</dl>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1222
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1223<p>When constructing the data layout for a given target, LLVM starts with a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1224 default set of specifications which are then (possibly) overriden by the
1225 specifications in the <tt>datalayout</tt> keyword. The default specifications
1226 are given in this list:</p>
1227
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1228<ul>
1229 <li><tt>E</tt> - big endian</li>
1230 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
1231 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
1232 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
1233 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
1234 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
Chris Lattner96451482008-08-05 18:29:16 +0000[diff] [blame]1235 <li><tt>i64:32:64</tt> - i64 has ABI alignment of 32-bits but preferred
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1236 alignment of 64-bits</li>
1237 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
1238 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
1239 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
1240 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
1241 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
Daniel Dunbard88a97b2009-06-08 22:17:53 +0000[diff] [blame]1242 <li><tt>s0:64:64</tt> - stack objects are 64-bit aligned</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1243</ul>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1244
1245<p>When LLVM is determining the alignment for a given type, it uses the
1246 following rules:</p>
1247
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1248<ol>
1249 <li>If the type sought is an exact match for one of the specifications, that
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1250 specification is used.</li>
1251
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1252 <li>If no match is found, and the type sought is an integer type, then the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1253 smallest integer type that is larger than the bitwidth of the sought type
1254 is used. If none of the specifications are larger than the bitwidth then
1255 the the largest integer type is used. For example, given the default
1256 specifications above, the i7 type will use the alignment of i8 (next
1257 largest) while both i65 and i256 will use the alignment of i64 (largest
1258 specified).</li>
1259
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1260 <li>If no match is found, and the type sought is a vector type, then the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1261 largest vector type that is smaller than the sought vector type will be
1262 used as a fall back. This happens because &lt;128 x double&gt; can be
1263 implemented in terms of 64 &lt;2 x double&gt;, for example.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1264</ol>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1265
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1266</div>
1267
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]1268<!-- ======================================================================= -->
1269<div class="doc_subsection">
1270 <a name="pointeraliasing">Pointer Aliasing Rules</a>
1271</div>
1272
1273<div class="doc_text">
1274
Andreas Bolka11fbf432009-07-29 00:02:05 +0000[diff] [blame]1275<p>Any memory access must be done through a pointer value associated
Andreas Bolka23bece42009-07-27 20:37:10 +0000[diff] [blame]1276with an address range of the memory access, otherwise the behavior
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]1277is undefined. Pointer values are associated with address ranges
1278according to the following rules:</p>
1279
1280<ul>
Andreas Bolka11fbf432009-07-29 00:02:05 +0000[diff] [blame]1281 <li>A pointer value formed from a
1282 <tt><a href="#i_getelementptr">getelementptr</a></tt> instruction
1283 is associated with the addresses associated with the first operand
1284 of the <tt>getelementptr</tt>.</li>
1285 <li>An address of a global variable is associated with the address
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]1286 range of the variable's storage.</li>
1287 <li>The result value of an allocation instruction is associated with
1288 the address range of the allocated storage.</li>
1289 <li>A null pointer in the default address-space is associated with
Andreas Bolka11fbf432009-07-29 00:02:05 +0000[diff] [blame]1290 no address.</li>
1291 <li>A pointer value formed by an
1292 <tt><a href="#i_inttoptr">inttoptr</a></tt> is associated with all
1293 address ranges of all pointer values that contribute (directly or
1294 indirectly) to the computation of the pointer's value.</li>
1295 <li>The result value of a
1296 <tt><a href="#i_bitcast">bitcast</a></tt> is associated with all
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]1297 addresses associated with the operand of the <tt>bitcast</tt>.</li>
1298 <li>An integer constant other than zero or a pointer value returned
1299 from a function not defined within LLVM may be associated with address
1300 ranges allocated through mechanisms other than those provided by
Andreas Bolka11fbf432009-07-29 00:02:05 +0000[diff] [blame]1301 LLVM. Such ranges shall not overlap with any ranges of addresses
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]1302 allocated by mechanisms provided by LLVM.</li>
1303 </ul>
1304
1305<p>LLVM IR does not associate types with memory. The result type of a
Andreas Bolka11fbf432009-07-29 00:02:05 +0000[diff] [blame]1306<tt><a href="#i_load">load</a></tt> merely indicates the size and
1307alignment of the memory from which to load, as well as the
1308interpretation of the value. The first operand of a
1309<tt><a href="#i_store">store</a></tt> similarly only indicates the size
1310and alignment of the store.</p>
Dan Gohman27b47012009-07-27 18:07:55 +0000[diff] [blame]1311
1312<p>Consequently, type-based alias analysis, aka TBAA, aka
1313<tt>-fstrict-aliasing</tt>, is not applicable to general unadorned
1314LLVM IR. <a href="#metadata">Metadata</a> may be used to encode
1315additional information which specialized optimization passes may use
1316to implement type-based alias analysis.</p>
1317
1318</div>
1319
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1320<!-- *********************************************************************** -->
1321<div class="doc_section"> <a name="typesystem">Type System</a> </div>
1322<!-- *********************************************************************** -->
1323
1324<div class="doc_text">
1325
1326<p>The LLVM type system is one of the most important features of the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1327 intermediate representation. Being typed enables a number of optimizations
1328 to be performed on the intermediate representation directly, without having
1329 to do extra analyses on the side before the transformation. A strong type
1330 system makes it easier to read the generated code and enables novel analyses
1331 and transformations that are not feasible to perform on normal three address
1332 code representations.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1333
1334</div>
1335
1336<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1337<div class="doc_subsection"> <a name="t_classifications">Type
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1338Classifications</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1339
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1340<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1341
1342<p>The types fall into a few useful classifications:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1343
1344<table border="1" cellspacing="0" cellpadding="4">
1345 <tbody>
1346 <tr><th>Classification</th><th>Types</th></tr>
1347 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1348 <td><a href="#t_integer">integer</a></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1349 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1350 </tr>
1351 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1352 <td><a href="#t_floating">floating point</a></td>
1353 <td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1354 </tr>
1355 <tr>
1356 <td><a name="t_firstclass">first class</a></td>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1357 <td><a href="#t_integer">integer</a>,
1358 <a href="#t_floating">floating point</a>,
1359 <a href="#t_pointer">pointer</a>,
Dan Gohmanf6237db2008-06-18 18:42:13 +0000[diff] [blame]1360 <a href="#t_vector">vector</a>,
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]1361 <a href="#t_struct">structure</a>,
1362 <a href="#t_array">array</a>,
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1363 <a href="#t_label">label</a>,
1364 <a href="#t_metadata">metadata</a>.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1365 </td>
1366 </tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1367 <tr>
1368 <td><a href="#t_primitive">primitive</a></td>
1369 <td><a href="#t_label">label</a>,
1370 <a href="#t_void">void</a>,
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1371 <a href="#t_floating">floating point</a>,
1372 <a href="#t_metadata">metadata</a>.</td>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1373 </tr>
1374 <tr>
1375 <td><a href="#t_derived">derived</a></td>
1376 <td><a href="#t_integer">integer</a>,
1377 <a href="#t_array">array</a>,
1378 <a href="#t_function">function</a>,
1379 <a href="#t_pointer">pointer</a>,
1380 <a href="#t_struct">structure</a>,
1381 <a href="#t_pstruct">packed structure</a>,
1382 <a href="#t_vector">vector</a>,
1383 <a href="#t_opaque">opaque</a>.
Dan Gohman032ba852008-10-14 16:32:04 +0000[diff] [blame]1384 </td>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1385 </tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1386 </tbody>
1387</table>
1388
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1389<p>The <a href="#t_firstclass">first class</a> types are perhaps the most
1390 important. Values of these types are the only ones which can be produced by
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]1391 instructions.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1392
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1393</div>
1394
1395<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1396<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1397
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1398<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1399
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1400<p>The primitive types are the fundamental building blocks of the LLVM
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1401 system.</p>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1402
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1403</div>
1404
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1405<!-- _______________________________________________________________________ -->
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]1406<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1407
1408<div class="doc_text">
1409
1410<h5>Overview:</h5>
1411<p>The integer type is a very simple type that simply specifies an arbitrary
1412 bit width for the integer type desired. Any bit width from 1 bit to
1413 2<sup>23</sup>-1 (about 8 million) can be specified.</p>
1414
1415<h5>Syntax:</h5>
1416<pre>
1417 iN
1418</pre>
1419
1420<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1421 value.</p>
1422
1423<h5>Examples:</h5>
1424<table class="layout">
1425 <tr class="layout">
1426 <td class="left"><tt>i1</tt></td>
1427 <td class="left">a single-bit integer.</td>
1428 </tr>
1429 <tr class="layout">
1430 <td class="left"><tt>i32</tt></td>
1431 <td class="left">a 32-bit integer.</td>
1432 </tr>
1433 <tr class="layout">
1434 <td class="left"><tt>i1942652</tt></td>
1435 <td class="left">a really big integer of over 1 million bits.</td>
1436 </tr>
1437</table>
1438
1439<p>Note that the code generator does not yet support large integer types to be
1440 used as function return types. The specific limit on how large a return type
1441 the code generator can currently handle is target-dependent; currently it's
1442 often 64 bits for 32-bit targets and 128 bits for 64-bit targets.</p>
1443
1444</div>
1445
1446<!-- _______________________________________________________________________ -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1447<div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
1448
1449<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1450
1451<table>
1452 <tbody>
1453 <tr><th>Type</th><th>Description</th></tr>
1454 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
1455 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
1456 <tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
1457 <tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
1458 <tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
1459 </tbody>
1460</table>
1461
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1462</div>
1463
1464<!-- _______________________________________________________________________ -->
1465<div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
1466
1467<div class="doc_text">
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1468
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1469<h5>Overview:</h5>
1470<p>The void type does not represent any value and has no size.</p>
1471
1472<h5>Syntax:</h5>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1473<pre>
1474 void
1475</pre>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1476
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1477</div>
1478
1479<!-- _______________________________________________________________________ -->
1480<div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
1481
1482<div class="doc_text">
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1483
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1484<h5>Overview:</h5>
1485<p>The label type represents code labels.</p>
1486
1487<h5>Syntax:</h5>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1488<pre>
1489 label
1490</pre>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1491
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1492</div>
1493
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1494<!-- _______________________________________________________________________ -->
1495<div class="doc_subsubsection"> <a name="t_metadata">Metadata Type</a> </div>
1496
1497<div class="doc_text">
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1498
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1499<h5>Overview:</h5>
Nick Lewyckyeb021882009-09-27 23:27:42 +0000[diff] [blame]1500<p>The metadata type represents embedded metadata. No derived types may be
1501 created from metadata except for <a href="#t_function">function</a>
1502 arguments.
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1503
1504<h5>Syntax:</h5>
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1505<pre>
1506 metadata
1507</pre>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1508
Nick Lewycky29aaef82009-05-30 05:06:04 +0000[diff] [blame]1509</div>
1510
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1511
1512<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1513<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1514
1515<div class="doc_text">
1516
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1517<p>The real power in LLVM comes from the derived types in the system. This is
1518 what allows a programmer to represent arrays, functions, pointers, and other
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]1519 useful types. Each of these types contain one or more element types which
1520 may be a primitive type, or another derived type. For example, it is
1521 possible to have a two dimensional array, using an array as the element type
1522 of another array.</p>
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]1523
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1524</div>
1525
1526<!-- _______________________________________________________________________ -->
1527<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1528
1529<div class="doc_text">
1530
1531<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1532<p>The array type is a very simple derived type that arranges elements
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1533 sequentially in memory. The array type requires a size (number of elements)
1534 and an underlying data type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1535
1536<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1537<pre>
1538 [&lt;# elements&gt; x &lt;elementtype&gt;]
1539</pre>
1540
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1541<p>The number of elements is a constant integer value; <tt>elementtype</tt> may
1542 be any type with a size.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1543
1544<h5>Examples:</h5>
1545<table class="layout">
1546 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1547 <td class="left"><tt>[40 x i32]</tt></td>
1548 <td class="left">Array of 40 32-bit integer values.</td>
1549 </tr>
1550 <tr class="layout">
1551 <td class="left"><tt>[41 x i32]</tt></td>
1552 <td class="left">Array of 41 32-bit integer values.</td>
1553 </tr>
1554 <tr class="layout">
1555 <td class="left"><tt>[4 x i8]</tt></td>
1556 <td class="left">Array of 4 8-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1557 </tr>
1558</table>
1559<p>Here are some examples of multidimensional arrays:</p>
1560<table class="layout">
1561 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1562 <td class="left"><tt>[3 x [4 x i32]]</tt></td>
1563 <td class="left">3x4 array of 32-bit integer values.</td>
1564 </tr>
1565 <tr class="layout">
1566 <td class="left"><tt>[12 x [10 x float]]</tt></td>
1567 <td class="left">12x10 array of single precision floating point values.</td>
1568 </tr>
1569 <tr class="layout">
1570 <td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
1571 <td class="left">2x3x4 array of 16-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1572 </tr>
1573</table>
1574
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1575<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1576 length array. Normally, accesses past the end of an array are undefined in
1577 LLVM (e.g. it is illegal to access the 5th element of a 3 element array). As
1578 a special case, however, zero length arrays are recognized to be variable
1579 length. This allows implementation of 'pascal style arrays' with the LLVM
1580 type "<tt>{ i32, [0 x float]}</tt>", for example.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1581
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1582<p>Note that the code generator does not yet support large aggregate types to be
1583 used as function return types. The specific limit on how large an aggregate
1584 return type the code generator can currently handle is target-dependent, and
1585 also dependent on the aggregate element types.</p>
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]1586
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1587</div>
1588
1589<!-- _______________________________________________________________________ -->
1590<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1591
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1592<div class="doc_text">
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]1593
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1594<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1595<p>The function type can be thought of as a function signature. It consists of
1596 a return type and a list of formal parameter types. The return type of a
1597 function type is a scalar type, a void type, or a struct type. If the return
1598 type is a struct type then all struct elements must be of first class types,
1599 and the struct must have at least one element.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1600
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1601<h5>Syntax:</h5>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]1602<pre>
Nick Lewycky3b3b54d2009-09-27 07:55:32 +0000[diff] [blame]1603 &lt;returntype&gt; (&lt;parameter list&gt;)
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]1604</pre>
1605
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1606<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1607 specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1608 which indicates that the function takes a variable number of arguments.
1609 Variable argument functions can access their arguments with
1610 the <a href="#int_varargs">variable argument handling intrinsic</a>
Nick Lewycky3b3b54d2009-09-27 07:55:32 +0000[diff] [blame]1611 functions. '<tt>&lt;returntype&gt;</tt>' is a any type except
Nick Lewyckyeb021882009-09-27 23:27:42 +0000[diff] [blame]1612 <a href="#t_label">label</a>.</p>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]1613
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1614<h5>Examples:</h5>
1615<table class="layout">
1616 <tr class="layout">
1617 <td class="left"><tt>i32 (i32)</tt></td>
1618 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1619 </td>
1620 </tr><tr class="layout">
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]1621 <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1622 </tt></td>
1623 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1624 an <tt>i16</tt> that should be sign extended and a
1625 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1626 <tt>float</tt>.
1627 </td>
1628 </tr><tr class="layout">
1629 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1630 <td class="left">A vararg function that takes at least one
1631 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1632 which returns an integer. This is the signature for <tt>printf</tt> in
1633 LLVM.
1634 </td>
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1635 </tr><tr class="layout">
1636 <td class="left"><tt>{i32, i32} (i32)</tt></td>
Nick Lewycky3b3b54d2009-09-27 07:55:32 +0000[diff] [blame]1637 <td class="left">A function taking an <tt>i32</tt>, returning a
1638 <a href="#t_struct">structure</a> containing two <tt>i32</tt> values
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1639 </td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1640 </tr>
1641</table>
1642
1643</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1644
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1645<!-- _______________________________________________________________________ -->
1646<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1647
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1648<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1649
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1650<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1651<p>The structure type is used to represent a collection of data members together
1652 in memory. The packing of the field types is defined to match the ABI of the
1653 underlying processor. The elements of a structure may be any type that has a
1654 size.</p>
1655
1656<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt> and
1657 '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a field with
1658 the '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.</p>
1659
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1660<h5>Syntax:</h5>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1661<pre>
1662 { &lt;type list&gt; }
1663</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1664
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1665<h5>Examples:</h5>
1666<table class="layout">
1667 <tr class="layout">
1668 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1669 <td class="left">A triple of three <tt>i32</tt> values</td>
1670 </tr><tr class="layout">
1671 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1672 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1673 second element is a <a href="#t_pointer">pointer</a> to a
1674 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1675 an <tt>i32</tt>.</td>
1676 </tr>
1677</table>
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]1678
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1679<p>Note that the code generator does not yet support large aggregate types to be
1680 used as function return types. The specific limit on how large an aggregate
1681 return type the code generator can currently handle is target-dependent, and
1682 also dependent on the aggregate element types.</p>
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]1683
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1684</div>
1685
1686<!-- _______________________________________________________________________ -->
1687<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1688</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1689
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1690<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1691
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1692<h5>Overview:</h5>
1693<p>The packed structure type is used to represent a collection of data members
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1694 together in memory. There is no padding between fields. Further, the
1695 alignment of a packed structure is 1 byte. The elements of a packed
1696 structure may be any type that has a size.</p>
1697
1698<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt> and
1699 '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a field with
1700 the '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.</p>
1701
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1702<h5>Syntax:</h5>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1703<pre>
1704 &lt; { &lt;type list&gt; } &gt;
1705</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1706
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1707<h5>Examples:</h5>
1708<table class="layout">
1709 <tr class="layout">
1710 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1711 <td class="left">A triple of three <tt>i32</tt> values</td>
1712 </tr><tr class="layout">
Bill Wendling74d3eac2008-09-07 10:26:33 +0000[diff] [blame]1713 <td class="left">
1714<tt>&lt;&nbsp;{&nbsp;float,&nbsp;i32&nbsp;(i32)*&nbsp;}&nbsp;&gt;</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1715 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1716 second element is a <a href="#t_pointer">pointer</a> to a
1717 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1718 an <tt>i32</tt>.</td>
1719 </tr>
1720</table>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1721
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1722</div>
1723
1724<!-- _______________________________________________________________________ -->
1725<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Chris Lattner96edbd32009-02-08 19:53:29 +0000[diff] [blame]1726
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1727<div class="doc_text">
1728
1729<h5>Overview:</h5>
1730<p>As in many languages, the pointer type represents a pointer or reference to
1731 another object, which must live in memory. Pointer types may have an optional
1732 address space attribute defining the target-specific numbered address space
1733 where the pointed-to object resides. The default address space is zero.</p>
1734
1735<p>Note that LLVM does not permit pointers to void (<tt>void*</tt>) nor does it
1736 permit pointers to labels (<tt>label*</tt>). Use <tt>i8*</tt> instead.</p>
Chris Lattner96edbd32009-02-08 19:53:29 +0000[diff] [blame]1737
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1738<h5>Syntax:</h5>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]1739<pre>
1740 &lt;type&gt; *
1741</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1742
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1743<h5>Examples:</h5>
1744<table class="layout">
1745 <tr class="layout">
Dan Gohman01852382009-01-04 23:44:43 +0000[diff] [blame]1746 <td class="left"><tt>[4 x i32]*</tt></td>
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1747 <td class="left">A <a href="#t_pointer">pointer</a> to <a
1748 href="#t_array">array</a> of four <tt>i32</tt> values.</td>
1749 </tr>
1750 <tr class="layout">
1751 <td class="left"><tt>i32 (i32 *) *</tt></td>
1752 <td class="left"> A <a href="#t_pointer">pointer</a> to a <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1753 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1754 <tt>i32</tt>.</td>
1755 </tr>
1756 <tr class="layout">
1757 <td class="left"><tt>i32 addrspace(5)*</tt></td>
1758 <td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
1759 that resides in address space #5.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1760 </tr>
1761</table>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1762
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1763</div>
1764
1765<!-- _______________________________________________________________________ -->
1766<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1767
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1768<div class="doc_text">
1769
1770<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1771<p>A vector type is a simple derived type that represents a vector of elements.
1772 Vector types are used when multiple primitive data are operated in parallel
1773 using a single instruction (SIMD). A vector type requires a size (number of
1774 elements) and an underlying primitive data type. Vectors must have a power
1775 of two length (1, 2, 4, 8, 16 ...). Vector types are considered
1776 <a href="#t_firstclass">first class</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1777
1778<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1779<pre>
1780 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1781</pre>
1782
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1783<p>The number of elements is a constant integer value; elementtype may be any
1784 integer or floating point type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1785
1786<h5>Examples:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1787<table class="layout">
1788 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1789 <td class="left"><tt>&lt;4 x i32&gt;</tt></td>
1790 <td class="left">Vector of 4 32-bit integer values.</td>
1791 </tr>
1792 <tr class="layout">
1793 <td class="left"><tt>&lt;8 x float&gt;</tt></td>
1794 <td class="left">Vector of 8 32-bit floating-point values.</td>
1795 </tr>
1796 <tr class="layout">
1797 <td class="left"><tt>&lt;2 x i64&gt;</tt></td>
1798 <td class="left">Vector of 2 64-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1799 </tr>
1800</table>
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]1801
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1802<p>Note that the code generator does not yet support large vector types to be
1803 used as function return types. The specific limit on how large a vector
1804 return type codegen can currently handle is target-dependent; currently it's
1805 often a few times longer than a hardware vector register.</p>
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]1806
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1807</div>
1808
1809<!-- _______________________________________________________________________ -->
1810<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1811<div class="doc_text">
1812
1813<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1814<p>Opaque types are used to represent unknown types in the system. This
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1815 corresponds (for example) to the C notion of a forward declared structure
1816 type. In LLVM, opaque types can eventually be resolved to any type (not just
1817 a structure type).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1818
1819<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1820<pre>
1821 opaque
1822</pre>
1823
1824<h5>Examples:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1825<table class="layout">
1826 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1827 <td class="left"><tt>opaque</tt></td>
1828 <td class="left">An opaque type.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1829 </tr>
1830</table>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1831
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1832</div>
1833
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1834<!-- ======================================================================= -->
1835<div class="doc_subsection">
1836 <a name="t_uprefs">Type Up-references</a>
1837</div>
1838
1839<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1840
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1841<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1842<p>An "up reference" allows you to refer to a lexically enclosing type without
1843 requiring it to have a name. For instance, a structure declaration may
1844 contain a pointer to any of the types it is lexically a member of. Example
1845 of up references (with their equivalent as named type declarations)
1846 include:</p>
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1847
1848<pre>
Chris Lattner5ad632d2009-02-09 10:00:56 +0000[diff] [blame]1849 { \2 * } %x = type { %x* }
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1850 { \2 }* %y = type { %y }*
1851 \1* %z = type %z*
1852</pre>
1853
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1854<p>An up reference is needed by the asmprinter for printing out cyclic types
1855 when there is no declared name for a type in the cycle. Because the
1856 asmprinter does not want to print out an infinite type string, it needs a
1857 syntax to handle recursive types that have no names (all names are optional
1858 in llvm IR).</p>
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1859
1860<h5>Syntax:</h5>
1861<pre>
1862 \&lt;level&gt;
1863</pre>
1864
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1865<p>The level is the count of the lexical type that is being referred to.</p>
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1866
1867<h5>Examples:</h5>
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1868<table class="layout">
1869 <tr class="layout">
1870 <td class="left"><tt>\1*</tt></td>
1871 <td class="left">Self-referential pointer.</td>
1872 </tr>
1873 <tr class="layout">
1874 <td class="left"><tt>{ { \3*, i8 }, i32 }</tt></td>
1875 <td class="left">Recursive structure where the upref refers to the out-most
1876 structure.</td>
1877 </tr>
1878</table>
Chris Lattner515195a2009-02-02 07:32:36 +0000[diff] [blame]1879
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1880</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1881
1882<!-- *********************************************************************** -->
1883<div class="doc_section"> <a name="constants">Constants</a> </div>
1884<!-- *********************************************************************** -->
1885
1886<div class="doc_text">
1887
1888<p>LLVM has several different basic types of constants. This section describes
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1889 them all and their syntax.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1890
1891</div>
1892
1893<!-- ======================================================================= -->
1894<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1895
1896<div class="doc_text">
1897
1898<dl>
1899 <dt><b>Boolean constants</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1900 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]1901 constants of the <tt><a href="#t_integer">i1</a></tt> type.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1902
1903 <dt><b>Integer constants</b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1904 <dd>Standard integers (such as '4') are constants of
1905 the <a href="#t_integer">integer</a> type. Negative numbers may be used
1906 with integer types.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1907
1908 <dt><b>Floating point constants</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1909 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1910 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
1911 notation (see below). The assembler requires the exact decimal value of a
1912 floating-point constant. For example, the assembler accepts 1.25 but
1913 rejects 1.3 because 1.3 is a repeating decimal in binary. Floating point
1914 constants must have a <a href="#t_floating">floating point</a> type. </dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1915
1916 <dt><b>Null pointer constants</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1917 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1918 and must be of <a href="#t_pointer">pointer type</a>.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1919</dl>
1920
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1921<p>The one non-intuitive notation for constants is the hexadecimal form of
1922 floating point constants. For example, the form '<tt>double
1923 0x432ff973cafa8000</tt>' is equivalent to (but harder to read than)
1924 '<tt>double 4.5e+15</tt>'. The only time hexadecimal floating point
1925 constants are required (and the only time that they are generated by the
1926 disassembler) is when a floating point constant must be emitted but it cannot
1927 be represented as a decimal floating point number in a reasonable number of
1928 digits. For example, NaN's, infinities, and other special values are
1929 represented in their IEEE hexadecimal format so that assembly and disassembly
1930 do not cause any bits to change in the constants.</p>
1931
Dale Johannesenf82a52f2009-02-11 22:14:51 +0000[diff] [blame]1932<p>When using the hexadecimal form, constants of types float and double are
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1933 represented using the 16-digit form shown above (which matches the IEEE754
1934 representation for double); float values must, however, be exactly
1935 representable as IEE754 single precision. Hexadecimal format is always used
1936 for long double, and there are three forms of long double. The 80-bit format
1937 used by x86 is represented as <tt>0xK</tt> followed by 20 hexadecimal digits.
1938 The 128-bit format used by PowerPC (two adjacent doubles) is represented
1939 by <tt>0xM</tt> followed by 32 hexadecimal digits. The IEEE 128-bit format
1940 is represented by <tt>0xL</tt> followed by 32 hexadecimal digits; no
1941 currently supported target uses this format. Long doubles will only work if
1942 they match the long double format on your target. All hexadecimal formats
1943 are big-endian (sign bit at the left).</p>
1944
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1945</div>
1946
1947<!-- ======================================================================= -->
Chris Lattner97063852009-02-28 18:32:25 +0000[diff] [blame]1948<div class="doc_subsection">
Bill Wendling1a2630a2009-07-20 02:32:41 +0000[diff] [blame]1949<a name="aggregateconstants"></a> <!-- old anchor -->
1950<a name="complexconstants">Complex Constants</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1951</div>
1952
1953<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1954
Chris Lattner97063852009-02-28 18:32:25 +0000[diff] [blame]1955<p>Complex constants are a (potentially recursive) combination of simple
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1956 constants and smaller complex constants.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1957
1958<dl>
1959 <dt><b>Structure constants</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1960 <dd>Structure constants are represented with notation similar to structure
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1961 type definitions (a comma separated list of elements, surrounded by braces
1962 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
1963 where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>".
1964 Structure constants must have <a href="#t_struct">structure type</a>, and
1965 the number and types of elements must match those specified by the
1966 type.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1967
1968 <dt><b>Array constants</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1969 <dd>Array constants are represented with notation similar to array type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1970 definitions (a comma separated list of elements, surrounded by square
1971 brackets (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74
1972 ]</tt>". Array constants must have <a href="#t_array">array type</a>, and
1973 the number and types of elements must match those specified by the
1974 type.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1975
1976 <dt><b>Vector constants</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1977 <dd>Vector constants are represented with notation similar to vector type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1978 definitions (a comma separated list of elements, surrounded by
1979 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32
1980 42, i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must
1981 have <a href="#t_vector">vector type</a>, and the number and types of
1982 elements must match those specified by the type.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1983
1984 <dt><b>Zero initialization</b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1985 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1986 value to zero of <em>any</em> type, including scalar and aggregate types.
1987 This is often used to avoid having to print large zero initializers
1988 (e.g. for large arrays) and is always exactly equivalent to using explicit
1989 zero initializers.</dd>
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]1990
1991 <dt><b>Metadata node</b></dt>
Nick Lewyckyf122c7e2009-05-30 16:08:30 +0000[diff] [blame]1992 <dd>A metadata node is a structure-like constant with
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]1993 <a href="#t_metadata">metadata type</a>. For example: "<tt>metadata !{
1994 i32 0, metadata !"test" }</tt>". Unlike other constants that are meant to
1995 be interpreted as part of the instruction stream, metadata is a place to
1996 attach additional information such as debug info.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1997</dl>
1998
1999</div>
2000
2001<!-- ======================================================================= -->
2002<div class="doc_subsection">
2003 <a name="globalconstants">Global Variable and Function Addresses</a>
2004</div>
2005
2006<div class="doc_text">
2007
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2008<p>The addresses of <a href="#globalvars">global variables</a>
2009 and <a href="#functionstructure">functions</a> are always implicitly valid
2010 (link-time) constants. These constants are explicitly referenced when
2011 the <a href="#identifiers">identifier for the global</a> is used and always
2012 have <a href="#t_pointer">pointer</a> type. For example, the following is a
2013 legal LLVM file:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2014
2015<div class="doc_code">
2016<pre>
2017@X = global i32 17
2018@Y = global i32 42
2019@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
2020</pre>
2021</div>
2022
2023</div>
2024
2025<!-- ======================================================================= -->
2026<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
2027<div class="doc_text">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2028
Chris Lattner3d72cd82009-09-07 22:52:39 +0000[diff] [blame]2029<p>The string '<tt>undef</tt>' can be used anywhere a constant is expected, and
Benjamin Kramer5fb9d7e2009-10-12 14:46:08 +0000[diff] [blame]2030 indicates that the user of the value may receive an unspecified bit-pattern.
Chris Lattner3d72cd82009-09-07 22:52:39 +0000[diff] [blame]2031 Undefined values may be of any type (other than label or void) and be used
2032 anywhere a constant is permitted.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2033
Chris Lattner9d1e4fa2009-09-11 01:49:31 +0000[diff] [blame]2034<p>Undefined values are useful because they indicate to the compiler that the
Chris Lattner3d72cd82009-09-07 22:52:39 +0000[diff] [blame]2035 program is well defined no matter what value is used. This gives the
2036 compiler more freedom to optimize. Here are some examples of (potentially
2037 surprising) transformations that are valid (in pseudo IR):</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2038
Chris Lattner3d72cd82009-09-07 22:52:39 +0000[diff] [blame]2039
2040<div class="doc_code">
2041<pre>
2042 %A = add %X, undef
2043 %B = sub %X, undef
2044 %C = xor %X, undef
2045Safe:
2046 %A = undef
2047 %B = undef
2048 %C = undef
2049</pre>
2050</div>
2051
2052<p>This is safe because all of the output bits are affected by the undef bits.
2053Any output bit can have a zero or one depending on the input bits.</p>
2054
2055<div class="doc_code">
2056<pre>
2057 %A = or %X, undef
2058 %B = and %X, undef
2059Safe:
2060 %A = -1
2061 %B = 0
2062Unsafe:
2063 %A = undef
2064 %B = undef
2065</pre>
2066</div>
2067
2068<p>These logical operations have bits that are not always affected by the input.
2069For example, if "%X" has a zero bit, then the output of the 'and' operation will
2070always be a zero, no matter what the corresponding bit from the undef is. As
Chris Lattner9d1e4fa2009-09-11 01:49:31 +0000[diff] [blame]2071such, it is unsafe to optimize or assume that the result of the and is undef.
2072However, it is safe to assume that all bits of the undef could be 0, and
2073optimize the and to 0. Likewise, it is safe to assume that all the bits of
2074the undef operand to the or could be set, allowing the or to be folded to
2075-1.</p>
Chris Lattner3d72cd82009-09-07 22:52:39 +0000[diff] [blame]2076
2077<div class="doc_code">
2078<pre>
2079 %A = select undef, %X, %Y
2080 %B = select undef, 42, %Y
2081 %C = select %X, %Y, undef
2082Safe:
2083 %A = %X (or %Y)
2084 %B = 42 (or %Y)
2085 %C = %Y
2086Unsafe:
2087 %A = undef
2088 %B = undef
2089 %C = undef
2090</pre>
2091</div>
2092
2093<p>This set of examples show that undefined select (and conditional branch)
2094conditions can go "either way" but they have to come from one of the two
2095operands. In the %A example, if %X and %Y were both known to have a clear low
2096bit, then %A would have to have a cleared low bit. However, in the %C example,
2097the optimizer is allowed to assume that the undef operand could be the same as
2098%Y, allowing the whole select to be eliminated.</p>
2099
2100
2101<div class="doc_code">
2102<pre>
2103 %A = xor undef, undef
2104
2105 %B = undef
2106 %C = xor %B, %B
2107
2108 %D = undef
2109 %E = icmp lt %D, 4
2110 %F = icmp gte %D, 4
2111
2112Safe:
2113 %A = undef
2114 %B = undef
2115 %C = undef
2116 %D = undef
2117 %E = undef
2118 %F = undef
2119</pre>
2120</div>
2121
2122<p>This example points out that two undef operands are not necessarily the same.
2123This can be surprising to people (and also matches C semantics) where they
2124assume that "X^X" is always zero, even if X is undef. This isn't true for a
2125number of reasons, but the short answer is that an undef "variable" can
2126arbitrarily change its value over its "live range". This is true because the
2127"variable" doesn't actually <em>have a live range</em>. Instead, the value is
2128logically read from arbitrary registers that happen to be around when needed,
Benjamin Kramer5fb9d7e2009-10-12 14:46:08 +0000[diff] [blame]2129so the value is not necessarily consistent over time. In fact, %A and %C need
Chris Lattnerc802e482009-09-08 15:13:16 +0000[diff] [blame]2130to have the same semantics or the core LLVM "replace all uses with" concept
Chris Lattner3d72cd82009-09-07 22:52:39 +0000[diff] [blame]2131would not hold.</p>
Chris Lattner466291f2009-09-07 23:33:52 +0000[diff] [blame]2132
2133<div class="doc_code">
2134<pre>
2135 %A = fdiv undef, %X
2136 %B = fdiv %X, undef
2137Safe:
2138 %A = undef
2139b: unreachable
2140</pre>
2141</div>
2142
2143<p>These examples show the crucial difference between an <em>undefined
2144value</em> and <em>undefined behavior</em>. An undefined value (like undef) is
2145allowed to have an arbitrary bit-pattern. This means that the %A operation
2146can be constant folded to undef because the undef could be an SNaN, and fdiv is
2147not (currently) defined on SNaN's. However, in the second example, we can make
2148a more aggressive assumption: because the undef is allowed to be an arbitrary
2149value, we are allowed to assume that it could be zero. Since a divide by zero
Chris Lattner83d45d72009-09-08 19:45:34 +0000[diff] [blame]2150has <em>undefined behavior</em>, we are allowed to assume that the operation
Chris Lattner466291f2009-09-07 23:33:52 +0000[diff] [blame]2151does not execute at all. This allows us to delete the divide and all code after
2152it: since the undefined operation "can't happen", the optimizer can assume that
2153it occurs in dead code.
2154</p>
2155
2156<div class="doc_code">
2157<pre>
2158a: store undef -> %X
2159b: store %X -> undef
2160Safe:
2161a: &lt;deleted&gt;
2162b: unreachable
2163</pre>
2164</div>
2165
2166<p>These examples reiterate the fdiv example: a store "of" an undefined value
2167can be assumed to not have any effect: we can assume that the value is
2168overwritten with bits that happen to match what was already there. However, a
2169store "to" an undefined location could clobber arbitrary memory, therefore, it
2170has undefined behavior.</p>
2171
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2172</div>
2173
2174<!-- ======================================================================= -->
Chris Lattner29246b52009-10-27 21:19:13 +0000[diff] [blame^]2175<div class="doc_subsection"><a name="blockaddress">Addresses of Basic
2176 Blocks</a></div>
Chris Lattnerd07c8372009-10-27 21:01:34 +0000[diff] [blame]2177<div class="doc_text">
2178
2179<p><b><tt>blockaddress(@function, %block)</tt></b></p>
2180
2181<p>The '<tt>blockaddress</tt>' constant computes the address of the specified
2182 basic block in the specified function, and always has an i8* type.</p>
2183
2184
2185<p>This value only has defined behavior when used as an operand to the
2186 '<a href="#i_indbr"><tt>indbr</tt></a>' instruction or for comparisons
2187 against null. Pointer equality tests between labels addresses is undefined
2188 behavior - though, again, comparison against null is ok, and no label is
Chris Lattner29246b52009-10-27 21:19:13 +0000[diff] [blame^]2189 equal to the null pointer. This may also be passed around as an opaque
2190 pointer sized value as long as the bits are not inspected. This allows
2191 ptrtoint and arithmetic to be performed on these values so long as the
2192 original value is reconsistituted before the <tt>indbr</tt>.</p>
2193
2194<p>Finally, some targets may provide defined semantics when
Chris Lattnerd07c8372009-10-27 21:01:34 +0000[diff] [blame]2195 using the value as the operand to an inline assembly, but that is target
2196 specific.
2197 </p>
2198
2199</div>
2200
2201
2202<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2203<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
2204</div>
2205
2206<div class="doc_text">
2207
2208<p>Constant expressions are used to allow expressions involving other constants
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2209 to be used as constants. Constant expressions may be of
2210 any <a href="#t_firstclass">first class</a> type and may involve any LLVM
2211 operation that does not have side effects (e.g. load and call are not
2212 supported). The following is the syntax for constant expressions:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2213
2214<dl>
2215 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2216 <dd>Truncate a constant to another type. The bit size of CST must be larger
2217 than the bit size of TYPE. Both types must be integers.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2218
2219 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2220 <dd>Zero extend a constant to another type. The bit size of CST must be
2221 smaller or equal to the bit size of TYPE. Both types must be
2222 integers.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2223
2224 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2225 <dd>Sign extend a constant to another type. The bit size of CST must be
2226 smaller or equal to the bit size of TYPE. Both types must be
2227 integers.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2228
2229 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2230 <dd>Truncate a floating point constant to another floating point type. The
2231 size of CST must be larger than the size of TYPE. Both types must be
2232 floating point.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2233
2234 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2235 <dd>Floating point extend a constant to another type. The size of CST must be
2236 smaller or equal to the size of TYPE. Both types must be floating
2237 point.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2238
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]2239 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2240 <dd>Convert a floating point constant to the corresponding unsigned integer
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2241 constant. TYPE must be a scalar or vector integer type. CST must be of
2242 scalar or vector floating point type. Both CST and TYPE must be scalars,
2243 or vectors of the same number of elements. If the value won't fit in the
2244 integer type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2245
2246 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
2247 <dd>Convert a floating point constant to the corresponding signed integer
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2248 constant. TYPE must be a scalar or vector integer type. CST must be of
2249 scalar or vector floating point type. Both CST and TYPE must be scalars,
2250 or vectors of the same number of elements. If the value won't fit in the
2251 integer type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2252
2253 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
2254 <dd>Convert an unsigned integer constant to the corresponding floating point
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2255 constant. TYPE must be a scalar or vector floating point type. CST must be
2256 of scalar or vector integer type. Both CST and TYPE must be scalars, or
2257 vectors of the same number of elements. If the value won't fit in the
2258 floating point type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2259
2260 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
2261 <dd>Convert a signed integer constant to the corresponding floating point
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2262 constant. TYPE must be a scalar or vector floating point type. CST must be
2263 of scalar or vector integer type. Both CST and TYPE must be scalars, or
2264 vectors of the same number of elements. If the value won't fit in the
2265 floating point type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2266
2267 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
2268 <dd>Convert a pointer typed constant to the corresponding integer constant
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2269 <tt>TYPE</tt> must be an integer type. <tt>CST</tt> must be of pointer
2270 type. The <tt>CST</tt> value is zero extended, truncated, or unchanged to
2271 make it fit in <tt>TYPE</tt>.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2272
2273 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2274 <dd>Convert a integer constant to a pointer constant. TYPE must be a pointer
2275 type. CST must be of integer type. The CST value is zero extended,
2276 truncated, or unchanged to make it fit in a pointer size. This one is
2277 <i>really</i> dangerous!</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2278
2279 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Chris Lattner557bc5d2009-02-28 18:27:03 +0000[diff] [blame]2280 <dd>Convert a constant, CST, to another TYPE. The constraints of the operands
2281 are the same as those for the <a href="#i_bitcast">bitcast
2282 instruction</a>.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2283
2284 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
Dan Gohman106b2ae2009-07-27 21:53:46 +0000[diff] [blame]2285 <dt><b><tt>getelementptr inbounds ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2286 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2287 constants. As with the <a href="#i_getelementptr">getelementptr</a>
2288 instruction, the index list may have zero or more indexes, which are
2289 required to make sense for the type of "CSTPTR".</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2290
2291 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2292 <dd>Perform the <a href="#i_select">select operation</a> on constants.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2293
2294 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
2295 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
2296
2297 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
2298 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
2299
2300 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2301 <dd>Perform the <a href="#i_extractelement">extractelement operation</a> on
2302 constants.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2303
2304 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2305 <dd>Perform the <a href="#i_insertelement">insertelement operation</a> on
2306 constants.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2307
2308 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2309 <dd>Perform the <a href="#i_shufflevector">shufflevector operation</a> on
2310 constants.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2311
2312 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2313 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
2314 be any of the <a href="#binaryops">binary</a>
2315 or <a href="#bitwiseops">bitwise binary</a> operations. The constraints
2316 on operands are the same as those for the corresponding instruction
2317 (e.g. no bitwise operations on floating point values are allowed).</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2318</dl>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2319
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2320</div>
2321
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]2322<!-- ======================================================================= -->
2323<div class="doc_subsection"><a name="metadata">Embedded Metadata</a>
2324</div>
2325
2326<div class="doc_text">
2327
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2328<p>Embedded metadata provides a way to attach arbitrary data to the instruction
2329 stream without affecting the behaviour of the program. There are two
2330 metadata primitives, strings and nodes. All metadata has the
2331 <tt>metadata</tt> type and is identified in syntax by a preceding exclamation
2332 point ('<tt>!</tt>').</p>
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]2333
2334<p>A metadata string is a string surrounded by double quotes. It can contain
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2335 any character by escaping non-printable characters with "\xx" where "xx" is
2336 the two digit hex code. For example: "<tt>!"test\00"</tt>".</p>
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]2337
2338<p>Metadata nodes are represented with notation similar to structure constants
Benjamin Kramer5fb9d7e2009-10-12 14:46:08 +0000[diff] [blame]2339 (a comma separated list of elements, surrounded by braces and preceded by an
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2340 exclamation point). For example: "<tt>!{ metadata !"test\00", i32
2341 10}</tt>".</p>
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]2342
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2343<p>A metadata node will attempt to track changes to the values it holds. In the
2344 event that a value is deleted, it will be replaced with a typeless
2345 "<tt>null</tt>", such as "<tt>metadata !{null, i32 10}</tt>".</p>
Nick Lewycky117f4382009-05-10 20:57:05 +0000[diff] [blame]2346
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]2347<p>Optimizations may rely on metadata to provide additional information about
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2348 the program that isn't available in the instructions, or that isn't easily
2349 computable. Similarly, the code generator may expect a certain metadata
2350 format to be used to express debugging information.</p>
2351
Nick Lewycky4dcf8102009-04-04 07:22:01 +0000[diff] [blame]2352</div>
2353
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2354<!-- *********************************************************************** -->
2355<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
2356<!-- *********************************************************************** -->
2357
2358<!-- ======================================================================= -->
2359<div class="doc_subsection">
2360<a name="inlineasm">Inline Assembler Expressions</a>
2361</div>
2362
2363<div class="doc_text">
2364
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2365<p>LLVM supports inline assembler expressions (as opposed
2366 to <a href="#moduleasm"> Module-Level Inline Assembly</a>) through the use of
2367 a special value. This value represents the inline assembler as a string
2368 (containing the instructions to emit), a list of operand constraints (stored
Dale Johannesen648950f2009-10-13 21:56:55 +0000[diff] [blame]2369 as a string), a flag that indicates whether or not the inline asm
Dale Johannesen5ee3e4b2009-10-21 23:28:00 +0000[diff] [blame]2370 expression has side effects, and a flag indicating whether the function
2371 containing the asm needs to align its stack conservatively. An example
2372 inline assembler expression is:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2373
2374<div class="doc_code">
2375<pre>
2376i32 (i32) asm "bswap $0", "=r,r"
2377</pre>
2378</div>
2379
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2380<p>Inline assembler expressions may <b>only</b> be used as the callee operand of
2381 a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we
2382 have:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2383
2384<div class="doc_code">
2385<pre>
2386%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
2387</pre>
2388</div>
2389
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2390<p>Inline asms with side effects not visible in the constraint list must be
2391 marked as having side effects. This is done through the use of the
2392 '<tt>sideeffect</tt>' keyword, like so:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2393
2394<div class="doc_code">
2395<pre>
2396call void asm sideeffect "eieio", ""()
2397</pre>
2398</div>
2399
Dale Johannesen5ee3e4b2009-10-21 23:28:00 +0000[diff] [blame]2400<p>In some cases inline asms will contain code that will not work unless the
2401 stack is aligned in some way, such as calls or SSE instructions on x86,
2402 yet will not contain code that does that alignment within the asm.
2403 The compiler should make conservative assumptions about what the asm might
2404 contain and should generate its usual stack alignment code in the prologue
2405 if the '<tt>alignstack</tt>' keyword is present:</p>
Dale Johannesen648950f2009-10-13 21:56:55 +0000[diff] [blame]2406
2407<div class="doc_code">
2408<pre>
Dale Johannesen5ee3e4b2009-10-21 23:28:00 +0000[diff] [blame]2409call void asm alignstack "eieio", ""()
Dale Johannesen648950f2009-10-13 21:56:55 +0000[diff] [blame]2410</pre>
2411</div>
2412
2413<p>If both keywords appear the '<tt>sideeffect</tt>' keyword must come
2414 first.</p>
2415
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2416<p>TODO: The format of the asm and constraints string still need to be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2417 documented here. Constraints on what can be done (e.g. duplication, moving,
2418 etc need to be documented). This is probably best done by reference to
2419 another document that covers inline asm from a holistic perspective.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2420
2421</div>
2422
Chris Lattner75c24e02009-07-20 05:55:19 +0000[diff] [blame]2423
2424<!-- *********************************************************************** -->
2425<div class="doc_section">
2426 <a name="intrinsic_globals">Intrinsic Global Variables</a>
2427</div>
2428<!-- *********************************************************************** -->
2429
2430<p>LLVM has a number of "magic" global variables that contain data that affect
2431code generation or other IR semantics. These are documented here. All globals
Chris Lattner1e0e0d12009-07-20 06:14:25 +0000[diff] [blame]2432of this sort should have a section specified as "<tt>llvm.metadata</tt>". This
2433section and all globals that start with "<tt>llvm.</tt>" are reserved for use
2434by LLVM.</p>
Chris Lattner75c24e02009-07-20 05:55:19 +0000[diff] [blame]2435
2436<!-- ======================================================================= -->
2437<div class="doc_subsection">
2438<a name="intg_used">The '<tt>llvm.used</tt>' Global Variable</a>
2439</div>
2440
2441<div class="doc_text">
2442
2443<p>The <tt>@llvm.used</tt> global is an array with i8* element type which has <a
2444href="#linkage_appending">appending linkage</a>. This array contains a list of
2445pointers to global variables and functions which may optionally have a pointer
2446cast formed of bitcast or getelementptr. For example, a legal use of it is:</p>
2447
2448<pre>
2449 @X = global i8 4
2450 @Y = global i32 123
2451
2452 @llvm.used = appending global [2 x i8*] [
2453 i8* @X,
2454 i8* bitcast (i32* @Y to i8*)
2455 ], section "llvm.metadata"
2456</pre>
2457
2458<p>If a global variable appears in the <tt>@llvm.used</tt> list, then the
2459compiler, assembler, and linker are required to treat the symbol as if there is
2460a reference to the global that it cannot see. For example, if a variable has
2461internal linkage and no references other than that from the <tt>@llvm.used</tt>
2462list, it cannot be deleted. This is commonly used to represent references from
2463inline asms and other things the compiler cannot "see", and corresponds to
2464"attribute((used))" in GNU C.</p>
2465
2466<p>On some targets, the code generator must emit a directive to the assembler or
2467object file to prevent the assembler and linker from molesting the symbol.</p>
2468
2469</div>
2470
2471<!-- ======================================================================= -->
2472<div class="doc_subsection">
Chris Lattner1e0e0d12009-07-20 06:14:25 +0000[diff] [blame]2473<a name="intg_compiler_used">The '<tt>llvm.compiler.used</tt>' Global Variable</a>
2474</div>
2475
2476<div class="doc_text">
2477
2478<p>The <tt>@llvm.compiler.used</tt> directive is the same as the
2479<tt>@llvm.used</tt> directive, except that it only prevents the compiler from
2480touching the symbol. On targets that support it, this allows an intelligent
2481linker to optimize references to the symbol without being impeded as it would be
2482by <tt>@llvm.used</tt>.</p>
2483
2484<p>This is a rare construct that should only be used in rare circumstances, and
2485should not be exposed to source languages.</p>
2486
2487</div>
2488
2489<!-- ======================================================================= -->
2490<div class="doc_subsection">
Chris Lattner75c24e02009-07-20 05:55:19 +0000[diff] [blame]2491<a name="intg_global_ctors">The '<tt>llvm.global_ctors</tt>' Global Variable</a>
2492</div>
2493
2494<div class="doc_text">
2495
2496<p>TODO: Describe this.</p>
2497
2498</div>
2499
2500<!-- ======================================================================= -->
2501<div class="doc_subsection">
2502<a name="intg_global_dtors">The '<tt>llvm.global_dtors</tt>' Global Variable</a>
2503</div>
2504
2505<div class="doc_text">
2506
2507<p>TODO: Describe this.</p>
2508
2509</div>
2510
2511
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2512<!-- *********************************************************************** -->
2513<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
2514<!-- *********************************************************************** -->
2515
2516<div class="doc_text">
2517
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2518<p>The LLVM instruction set consists of several different classifications of
2519 instructions: <a href="#terminators">terminator
2520 instructions</a>, <a href="#binaryops">binary instructions</a>,
2521 <a href="#bitwiseops">bitwise binary instructions</a>,
2522 <a href="#memoryops">memory instructions</a>, and
2523 <a href="#otherops">other instructions</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2524
2525</div>
2526
2527<!-- ======================================================================= -->
2528<div class="doc_subsection"> <a name="terminators">Terminator
2529Instructions</a> </div>
2530
2531<div class="doc_text">
2532
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2533<p>As mentioned <a href="#functionstructure">previously</a>, every basic block
2534 in a program ends with a "Terminator" instruction, which indicates which
2535 block should be executed after the current block is finished. These
2536 terminator instructions typically yield a '<tt>void</tt>' value: they produce
2537 control flow, not values (the one exception being the
2538 '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
2539
2540<p>There are six different terminator instructions: the
2541 '<a href="#i_ret"><tt>ret</tt></a>' instruction, the
2542 '<a href="#i_br"><tt>br</tt></a>' instruction, the
2543 '<a href="#i_switch"><tt>switch</tt></a>' instruction, the
Chris Lattnere0787282009-10-27 19:13:16 +0000[diff] [blame]2544 '<a href="#i_indbr">'<tt>indbr</tt>' Instruction, the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2545 '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the
2546 '<a href="#i_unwind"><tt>unwind</tt></a>' instruction, and the
2547 '<a href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2548
2549</div>
2550
2551<!-- _______________________________________________________________________ -->
2552<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
2553Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2554
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2555<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2556
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2557<h5>Syntax:</h5>
Dan Gohman3e700032008-10-04 19:00:07 +0000[diff] [blame]2558<pre>
2559 ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2560 ret void <i>; Return from void function</i>
2561</pre>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]2562
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2563<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2564<p>The '<tt>ret</tt>' instruction is used to return control flow (and optionally
2565 a value) from a function back to the caller.</p>
2566
2567<p>There are two forms of the '<tt>ret</tt>' instruction: one that returns a
2568 value and then causes control flow, and one that just causes control flow to
2569 occur.</p>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]2570
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2571<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2572<p>The '<tt>ret</tt>' instruction optionally accepts a single argument, the
2573 return value. The type of the return value must be a
2574 '<a href="#t_firstclass">first class</a>' type.</p>
Dan Gohman3e700032008-10-04 19:00:07 +0000[diff] [blame]2575
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2576<p>A function is not <a href="#wellformed">well formed</a> if it it has a
2577 non-void return type and contains a '<tt>ret</tt>' instruction with no return
2578 value or a return value with a type that does not match its type, or if it
2579 has a void return type and contains a '<tt>ret</tt>' instruction with a
2580 return value.</p>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]2581
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2582<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2583<p>When the '<tt>ret</tt>' instruction is executed, control flow returns back to
2584 the calling function's context. If the caller is a
2585 "<a href="#i_call"><tt>call</tt></a>" instruction, execution continues at the
2586 instruction after the call. If the caller was an
2587 "<a href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues at
2588 the beginning of the "normal" destination block. If the instruction returns
2589 a value, that value shall set the call or invoke instruction's return
2590 value.</p>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]2591
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2592<h5>Example:</h5>
Chris Lattner43030e72008-04-23 04:59:35 +0000[diff] [blame]2593<pre>
2594 ret i32 5 <i>; Return an integer value of 5</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2595 ret void <i>; Return from a void function</i>
Bill Wendlingd163e2d2009-02-28 22:12:54 +0000[diff] [blame]2596 ret { i32, i8 } { i32 4, i8 2 } <i>; Return a struct of values 4 and 2</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2597</pre>
Dan Gohman60967192009-01-12 23:12:39 +0000[diff] [blame]2598
djge93155c2009-01-24 15:58:40 +0000[diff] [blame]2599<p>Note that the code generator does not yet fully support large
2600 return values. The specific sizes that are currently supported are
2601 dependent on the target. For integers, on 32-bit targets the limit
2602 is often 64 bits, and on 64-bit targets the limit is often 128 bits.
2603 For aggregate types, the current limits are dependent on the element
2604 types; for example targets are often limited to 2 total integer
2605 elements and 2 total floating-point elements.</p>
Dan Gohman60967192009-01-12 23:12:39 +0000[diff] [blame]2606
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2607</div>
2608<!-- _______________________________________________________________________ -->
2609<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2610
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2611<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2612
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2613<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2614<pre>
2615 br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2616</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2617
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2618<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2619<p>The '<tt>br</tt>' instruction is used to cause control flow to transfer to a
2620 different basic block in the current function. There are two forms of this
2621 instruction, corresponding to a conditional branch and an unconditional
2622 branch.</p>
2623
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2624<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2625<p>The conditional branch form of the '<tt>br</tt>' instruction takes a single
2626 '<tt>i1</tt>' value and two '<tt>label</tt>' values. The unconditional form
2627 of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>' value as a
2628 target.</p>
2629
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2630<h5>Semantics:</h5>
2631<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2632 argument is evaluated. If the value is <tt>true</tt>, control flows to the
2633 '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
2634 control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
2635
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2636<h5>Example:</h5>
Bill Wendling6ec40612009-07-20 02:39:26 +0000[diff] [blame]2637<pre>
2638Test:
2639 %cond = <a href="#i_icmp">icmp</a> eq i32 %a, %b
2640 br i1 %cond, label %IfEqual, label %IfUnequal
2641IfEqual:
2642 <a href="#i_ret">ret</a> i32 1
2643IfUnequal:
2644 <a href="#i_ret">ret</a> i32 0
2645</pre>
2646
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2647</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2648
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2649<!-- _______________________________________________________________________ -->
2650<div class="doc_subsubsection">
2651 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
2652</div>
2653
2654<div class="doc_text">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2655
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2656<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2657<pre>
2658 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
2659</pre>
2660
2661<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2662<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2663 several different places. It is a generalization of the '<tt>br</tt>'
2664 instruction, allowing a branch to occur to one of many possible
2665 destinations.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2666
2667<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2668<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2669 comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination,
2670 and an array of pairs of comparison value constants and '<tt>label</tt>'s.
2671 The table is not allowed to contain duplicate constant entries.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2672
2673<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2674<p>The <tt>switch</tt> instruction specifies a table of values and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2675 destinations. When the '<tt>switch</tt>' instruction is executed, this table
2676 is searched for the given value. If the value is found, control flow is
Benjamin Kramer5fb9d7e2009-10-12 14:46:08 +0000[diff] [blame]2677 transferred to the corresponding destination; otherwise, control flow is
2678 transferred to the default destination.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2679
2680<h5>Implementation:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2681<p>Depending on properties of the target machine and the particular
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2682 <tt>switch</tt> instruction, this instruction may be code generated in
2683 different ways. For example, it could be generated as a series of chained
2684 conditional branches or with a lookup table.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2685
2686<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2687<pre>
2688 <i>; Emulate a conditional br instruction</i>
2689 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Dan Gohman01852382009-01-04 23:44:43 +0000[diff] [blame]2690 switch i32 %Val, label %truedest [ i32 0, label %falsedest ]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2691
2692 <i>; Emulate an unconditional br instruction</i>
2693 switch i32 0, label %dest [ ]
2694
2695 <i>; Implement a jump table:</i>
Dan Gohman01852382009-01-04 23:44:43 +0000[diff] [blame]2696 switch i32 %val, label %otherwise [ i32 0, label %onzero
2697 i32 1, label %onone
2698 i32 2, label %ontwo ]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2699</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2700
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2701</div>
2702
Chris Lattnere0787282009-10-27 19:13:16 +0000[diff] [blame]2703
2704<!-- _______________________________________________________________________ -->
2705<div class="doc_subsubsection">
2706 <a name="i_indbr">'<tt>indbr</tt>' Instruction</a>
2707</div>
2708
2709<div class="doc_text">
2710
2711<h5>Syntax:</h5>
2712<pre>
2713 indbr &lt;somety&gt;* &lt;address&gt;, [ label &lt;dest1&gt;, label &lt;dest2&gt;, ... ]
2714</pre>
2715
2716<h5>Overview:</h5>
2717
2718<p>The '<tt>indbr</tt>' instruction implements an indirect branch to a label
2719 within the current function, whose address is specified by
Chris Lattnerd07c8372009-10-27 21:01:34 +0000[diff] [blame]2720 "<tt>address</tt>". Address must be derived from a <a
2721 href="#blockaddress">blockaddress</a> constant.</p>
Chris Lattnere0787282009-10-27 19:13:16 +0000[diff] [blame]2722
2723<h5>Arguments:</h5>
2724
2725<p>The '<tt>address</tt>' argument is the address of the label to jump to. The
2726 rest of the arguments indicate the full set of possible destinations that the
2727 address may point to. Blocks are allowed to occur multiple times in the
2728 destination list, though this isn't particularly useful.</p>
2729
2730<p>This destination list is required so that dataflow analysis has an accurate
2731 understanding of the CFG.</p>
2732
2733<h5>Semantics:</h5>
2734
2735<p>Control transfers to the block specified in the address argument. All
2736 possible destination blocks must be listed in the label list, otherwise this
2737 instruction has undefined behavior. This implies that jumps to labels
2738 defined in other functions have undefined behavior as well.</p>
2739
2740<h5>Implementation:</h5>
2741
2742<p>This is typically implemented with a jump through a register.</p>
2743
2744<h5>Example:</h5>
2745<pre>
Chris Lattner1e6c6eb2009-10-27 20:27:24 +0000[diff] [blame]2746 indbr i8* %Addr, [ label %bb1, label %bb2, label %bb3 ]
Chris Lattnere0787282009-10-27 19:13:16 +0000[diff] [blame]2747</pre>
2748
2749</div>
2750
2751
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2752<!-- _______________________________________________________________________ -->
2753<div class="doc_subsubsection">
2754 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
2755</div>
2756
2757<div class="doc_text">
2758
2759<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2760<pre>
Devang Pateld0bfcc72008-10-07 17:48:33 +0000[diff] [blame]2761 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] &lt;ptr to function ty&gt; &lt;function ptr val&gt;(&lt;function args&gt;) [<a href="#fnattrs">fn attrs</a>]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2762 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
2763</pre>
2764
2765<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2766<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2767 function, with the possibility of control flow transfer to either the
2768 '<tt>normal</tt>' label or the '<tt>exception</tt>' label. If the callee
2769 function returns with the "<tt><a href="#i_ret">ret</a></tt>" instruction,
2770 control flow will return to the "normal" label. If the callee (or any
2771 indirect callees) returns with the "<a href="#i_unwind"><tt>unwind</tt></a>"
2772 instruction, control is interrupted and continued at the dynamically nearest
2773 "exception" label.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2774
2775<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2776<p>This instruction requires several arguments:</p>
2777
2778<ol>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2779 <li>The optional "cconv" marker indicates which <a href="#callingconv">calling
2780 convention</a> the call should use. If none is specified, the call
2781 defaults to using C calling conventions.</li>
Devang Patelac2fc272008-10-06 18:50:38 +0000[diff] [blame]2782
2783 <li>The optional <a href="#paramattrs">Parameter Attributes</a> list for
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2784 return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>', and
2785 '<tt>inreg</tt>' attributes are valid here.</li>
Devang Patelac2fc272008-10-06 18:50:38 +0000[diff] [blame]2786
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2787 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2788 function value being invoked. In most cases, this is a direct function
2789 invocation, but indirect <tt>invoke</tt>s are just as possible, branching
2790 off an arbitrary pointer to function value.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2791
2792 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2793 function to be invoked. </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2794
2795 <li>'<tt>function args</tt>': argument list whose types match the function
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2796 signature argument types. If the function signature indicates the
2797 function accepts a variable number of arguments, the extra arguments can
2798 be specified.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2799
2800 <li>'<tt>normal label</tt>': the label reached when the called function
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2801 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2802
2803 <li>'<tt>exception label</tt>': the label reached when a callee returns with
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2804 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2805
Devang Pateld0bfcc72008-10-07 17:48:33 +0000[diff] [blame]2806 <li>The optional <a href="#fnattrs">function attributes</a> list. Only
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2807 '<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
2808 '<tt>readnone</tt>' attributes are valid here.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2809</ol>
2810
2811<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2812<p>This instruction is designed to operate as a standard
2813 '<tt><a href="#i_call">call</a></tt>' instruction in most regards. The
2814 primary difference is that it establishes an association with a label, which
2815 is used by the runtime library to unwind the stack.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2816
2817<p>This instruction is used in languages with destructors to ensure that proper
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2818 cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
2819 exception. Additionally, this is important for implementation of
2820 '<tt>catch</tt>' clauses in high-level languages that support them.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2821
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2822<p>For the purposes of the SSA form, the definition of the value returned by the
2823 '<tt>invoke</tt>' instruction is deemed to occur on the edge from the current
2824 block to the "normal" label. If the callee unwinds then no return value is
2825 available.</p>
Dan Gohman140ba5d2009-05-22 21:47:08 +0000[diff] [blame]2826
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2827<h5>Example:</h5>
2828<pre>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]2829 %retval = invoke i32 @Test(i32 15) to label %Continue
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2830 unwind label %TestCleanup <i>; {i32}:retval set</i>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]2831 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Testfnptr(i32 15) to label %Continue
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2832 unwind label %TestCleanup <i>; {i32}:retval set</i>
2833</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2834
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2835</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2836
2837<!-- _______________________________________________________________________ -->
2838
2839<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
2840Instruction</a> </div>
2841
2842<div class="doc_text">
2843
2844<h5>Syntax:</h5>
2845<pre>
2846 unwind
2847</pre>
2848
2849<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2850<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2851 at the first callee in the dynamic call stack which used
2852 an <a href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call.
2853 This is primarily used to implement exception handling.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2854
2855<h5>Semantics:</h5>
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame]2856<p>The '<tt>unwind</tt>' instruction causes execution of the current function to
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2857 immediately halt. The dynamic call stack is then searched for the
2858 first <a href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack.
2859 Once found, execution continues at the "exceptional" destination block
2860 specified by the <tt>invoke</tt> instruction. If there is no <tt>invoke</tt>
2861 instruction in the dynamic call chain, undefined behavior results.</p>
2862
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2863</div>
2864
2865<!-- _______________________________________________________________________ -->
2866
2867<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
2868Instruction</a> </div>
2869
2870<div class="doc_text">
2871
2872<h5>Syntax:</h5>
2873<pre>
2874 unreachable
2875</pre>
2876
2877<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2878<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2879 instruction is used to inform the optimizer that a particular portion of the
2880 code is not reachable. This can be used to indicate that the code after a
2881 no-return function cannot be reached, and other facts.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2882
2883<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2884<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2885
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2886</div>
2887
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2888<!-- ======================================================================= -->
2889<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2890
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2891<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2892
2893<p>Binary operators are used to do most of the computation in a program. They
2894 require two operands of the same type, execute an operation on them, and
2895 produce a single value. The operands might represent multiple data, as is
2896 the case with the <a href="#t_vector">vector</a> data type. The result value
2897 has the same type as its operands.</p>
2898
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2899<p>There are several different binary operators:</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2900
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2901</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2902
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2903<!-- _______________________________________________________________________ -->
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2904<div class="doc_subsubsection">
2905 <a name="i_add">'<tt>add</tt>' Instruction</a>
2906</div>
2907
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2908<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2909
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2910<h5>Syntax:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2911<pre>
Dan Gohmaned5fcb22009-07-20 22:41:19 +0000[diff] [blame]2912 &lt;result&gt; = add &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanb3b03482009-09-02 17:31:42 +0000[diff] [blame]2913 &lt;result&gt; = add nuw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
2914 &lt;result&gt; = add nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
2915 &lt;result&gt; = add nuw nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2916</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2917
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2918<h5>Overview:</h5>
2919<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2920
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2921<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2922<p>The two arguments to the '<tt>add</tt>' instruction must
2923 be <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
2924 integer values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2925
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2926<h5>Semantics:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2927<p>The value produced is the integer sum of the two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2928
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2929<p>If the sum has unsigned overflow, the result returned is the mathematical
2930 result modulo 2<sup>n</sup>, where n is the bit width of the result.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2931
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2932<p>Because LLVM integers use a two's complement representation, this instruction
2933 is appropriate for both signed and unsigned integers.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2934
Dan Gohman46e96012009-07-22 22:44:56 +0000[diff] [blame]2935<p><tt>nuw</tt> and <tt>nsw</tt> stand for &quot;No Unsigned Wrap&quot;
2936 and &quot;No Signed Wrap&quot;, respectively. If the <tt>nuw</tt> and/or
2937 <tt>nsw</tt> keywords are present, the result value of the <tt>add</tt>
2938 is undefined if unsigned and/or signed overflow, respectively, occurs.</p>
Dan Gohmaned5fcb22009-07-20 22:41:19 +0000[diff] [blame]2939
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2940<h5>Example:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2941<pre>
2942 &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2943</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2944
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2945</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2946
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2947<!-- _______________________________________________________________________ -->
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2948<div class="doc_subsubsection">
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2949 <a name="i_fadd">'<tt>fadd</tt>' Instruction</a>
2950</div>
2951
2952<div class="doc_text">
2953
2954<h5>Syntax:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2955<pre>
2956 &lt;result&gt; = fadd &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
2957</pre>
2958
2959<h5>Overview:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2960<p>The '<tt>fadd</tt>' instruction returns the sum of its two operands.</p>
2961
2962<h5>Arguments:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2963<p>The two arguments to the '<tt>fadd</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2964 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
2965 floating point values. Both arguments must have identical types.</p>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2966
2967<h5>Semantics:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2968<p>The value produced is the floating point sum of the two operands.</p>
2969
2970<h5>Example:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2971<pre>
2972 &lt;result&gt; = fadd float 4.0, %var <i>; yields {float}:result = 4.0 + %var</i>
2973</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2974
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2975</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2976
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]2977<!-- _______________________________________________________________________ -->
2978<div class="doc_subsubsection">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2979 <a name="i_sub">'<tt>sub</tt>' Instruction</a>
2980</div>
2981
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2982<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2983
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2984<h5>Syntax:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2985<pre>
Dan Gohman46e96012009-07-22 22:44:56 +0000[diff] [blame]2986 &lt;result&gt; = sub &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanb3b03482009-09-02 17:31:42 +0000[diff] [blame]2987 &lt;result&gt; = sub nuw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
2988 &lt;result&gt; = sub nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
2989 &lt;result&gt; = sub nuw nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2990</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2991
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2992<h5>Overview:</h5>
2993<p>The '<tt>sub</tt>' instruction returns the difference of its two
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2994 operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2995
2996<p>Note that the '<tt>sub</tt>' instruction is used to represent the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]2997 '<tt>neg</tt>' instruction present in most other intermediate
2998 representations.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]2999
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3000<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3001<p>The two arguments to the '<tt>sub</tt>' instruction must
3002 be <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
3003 integer values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3004
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3005<h5>Semantics:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3006<p>The value produced is the integer difference of the two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3007
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3008<p>If the difference has unsigned overflow, the result returned is the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3009 mathematical result modulo 2<sup>n</sup>, where n is the bit width of the
3010 result.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3011
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3012<p>Because LLVM integers use a two's complement representation, this instruction
3013 is appropriate for both signed and unsigned integers.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3014
Dan Gohman46e96012009-07-22 22:44:56 +0000[diff] [blame]3015<p><tt>nuw</tt> and <tt>nsw</tt> stand for &quot;No Unsigned Wrap&quot;
3016 and &quot;No Signed Wrap&quot;, respectively. If the <tt>nuw</tt> and/or
3017 <tt>nsw</tt> keywords are present, the result value of the <tt>sub</tt>
3018 is undefined if unsigned and/or signed overflow, respectively, occurs.</p>
Dan Gohmaned5fcb22009-07-20 22:41:19 +0000[diff] [blame]3019
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3020<h5>Example:</h5>
3021<pre>
3022 &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
3023 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
3024</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3025
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3026</div>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3027
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3028<!-- _______________________________________________________________________ -->
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3029<div class="doc_subsubsection">
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3030 <a name="i_fsub">'<tt>fsub</tt>' Instruction</a>
3031</div>
3032
3033<div class="doc_text">
3034
3035<h5>Syntax:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3036<pre>
3037 &lt;result&gt; = fsub &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
3038</pre>
3039
3040<h5>Overview:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3041<p>The '<tt>fsub</tt>' instruction returns the difference of its two
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3042 operands.</p>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3043
3044<p>Note that the '<tt>fsub</tt>' instruction is used to represent the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3045 '<tt>fneg</tt>' instruction present in most other intermediate
3046 representations.</p>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3047
3048<h5>Arguments:</h5>
Bill Wendling1a2630a2009-07-20 02:32:41 +0000[diff] [blame]3049<p>The two arguments to the '<tt>fsub</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3050 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
3051 floating point values. Both arguments must have identical types.</p>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3052
3053<h5>Semantics:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3054<p>The value produced is the floating point difference of the two operands.</p>
3055
3056<h5>Example:</h5>
3057<pre>
3058 &lt;result&gt; = fsub float 4.0, %var <i>; yields {float}:result = 4.0 - %var</i>
3059 &lt;result&gt; = fsub float -0.0, %val <i>; yields {float}:result = -%var</i>
3060</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3061
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3062</div>
3063
3064<!-- _______________________________________________________________________ -->
3065<div class="doc_subsubsection">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3066 <a name="i_mul">'<tt>mul</tt>' Instruction</a>
3067</div>
3068
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3069<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3070
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3071<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3072<pre>
Dan Gohman46e96012009-07-22 22:44:56 +0000[diff] [blame]3073 &lt;result&gt; = mul &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanb3b03482009-09-02 17:31:42 +0000[diff] [blame]3074 &lt;result&gt; = mul nuw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
3075 &lt;result&gt; = mul nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
3076 &lt;result&gt; = mul nuw nsw &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3077</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3078
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3079<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3080<p>The '<tt>mul</tt>' instruction returns the product of its two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3081
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3082<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3083<p>The two arguments to the '<tt>mul</tt>' instruction must
3084 be <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
3085 integer values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3086
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3087<h5>Semantics:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3088<p>The value produced is the integer product of the two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3089
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3090<p>If the result of the multiplication has unsigned overflow, the result
3091 returned is the mathematical result modulo 2<sup>n</sup>, where n is the bit
3092 width of the result.</p>
3093
3094<p>Because LLVM integers use a two's complement representation, and the result
3095 is the same width as the operands, this instruction returns the correct
3096 result for both signed and unsigned integers. If a full product
3097 (e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands should
3098 be sign-extended or zero-extended as appropriate to the width of the full
3099 product.</p>
3100
Dan Gohman46e96012009-07-22 22:44:56 +0000[diff] [blame]3101<p><tt>nuw</tt> and <tt>nsw</tt> stand for &quot;No Unsigned Wrap&quot;
3102 and &quot;No Signed Wrap&quot;, respectively. If the <tt>nuw</tt> and/or
3103 <tt>nsw</tt> keywords are present, the result value of the <tt>mul</tt>
3104 is undefined if unsigned and/or signed overflow, respectively, occurs.</p>
Dan Gohmaned5fcb22009-07-20 22:41:19 +0000[diff] [blame]3105
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3106<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3107<pre>
3108 &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3109</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3110
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3111</div>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3112
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3113<!-- _______________________________________________________________________ -->
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3114<div class="doc_subsubsection">
3115 <a name="i_fmul">'<tt>fmul</tt>' Instruction</a>
3116</div>
3117
3118<div class="doc_text">
3119
3120<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3121<pre>
3122 &lt;result&gt; = fmul &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3123</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3124
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3125<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3126<p>The '<tt>fmul</tt>' instruction returns the product of its two operands.</p>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3127
3128<h5>Arguments:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3129<p>The two arguments to the '<tt>fmul</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3130 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
3131 floating point values. Both arguments must have identical types.</p>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3132
3133<h5>Semantics:</h5>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3134<p>The value produced is the floating point product of the two operands.</p>
3135
3136<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3137<pre>
3138 &lt;result&gt; = fmul float 4.0, %var <i>; yields {float}:result = 4.0 * %var</i>
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3139</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3140
Dan Gohman7ce405e2009-06-04 22:49:04 +0000[diff] [blame]3141</div>
3142
3143<!-- _______________________________________________________________________ -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3144<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
3145</a></div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3146
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3147<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3148
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3149<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3150<pre>
3151 &lt;result&gt; = udiv &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3152</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3153
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3154<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3155<p>The '<tt>udiv</tt>' instruction returns the quotient of its two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3156
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3157<h5>Arguments:</h5>
3158<p>The two arguments to the '<tt>udiv</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3159 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3160 values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3161
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3162<h5>Semantics:</h5>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3163<p>The value produced is the unsigned integer quotient of the two operands.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3164
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3165<p>Note that unsigned integer division and signed integer division are distinct
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3166 operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
3167
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3168<p>Division by zero leads to undefined behavior.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3169
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3170<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3171<pre>
3172 &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3173</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3174
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3175</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3176
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3177<!-- _______________________________________________________________________ -->
3178<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
3179</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3180
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3181<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3182
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3183<h5>Syntax:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3184<pre>
Dan Gohmaned5fcb22009-07-20 22:41:19 +0000[diff] [blame]3185 &lt;result&gt; = sdiv &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanb3b03482009-09-02 17:31:42 +0000[diff] [blame]3186 &lt;result&gt; = sdiv exact &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3187</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3188
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3189<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3190<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3191
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3192<h5>Arguments:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3193<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3194 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3195 values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3196
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3197<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3198<p>The value produced is the signed integer quotient of the two operands rounded
3199 towards zero.</p>
3200
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3201<p>Note that signed integer division and unsigned integer division are distinct
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3202 operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
3203
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3204<p>Division by zero leads to undefined behavior. Overflow also leads to
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3205 undefined behavior; this is a rare case, but can occur, for example, by doing
3206 a 32-bit division of -2147483648 by -1.</p>
3207
Dan Gohman67fa48e2009-07-22 00:04:19 +0000[diff] [blame]3208<p>If the <tt>exact</tt> keyword is present, the result value of the
3209 <tt>sdiv</tt> is undefined if the result would be rounded or if overflow
3210 would occur.</p>
Dan Gohmaned5fcb22009-07-20 22:41:19 +0000[diff] [blame]3211
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3212<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3213<pre>
3214 &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3215</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3216
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3217</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3218
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3219<!-- _______________________________________________________________________ -->
3220<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
3221Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3222
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3223<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3224
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3225<h5>Syntax:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3226<pre>
Gabor Greifd9068fe2008-08-07 21:46:00 +0000[diff] [blame]3227 &lt;result&gt; = fdiv &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3228</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3229
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3230<h5>Overview:</h5>
3231<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3232
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3233<h5>Arguments:</h5>
3234<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3235 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
3236 floating point values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3237
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3238<h5>Semantics:</h5>
3239<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3240
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3241<h5>Example:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3242<pre>
3243 &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3244</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3245
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3246</div>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3247
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3248<!-- _______________________________________________________________________ -->
3249<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
3250</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3251
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3252<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3253
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3254<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3255<pre>
3256 &lt;result&gt; = urem &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3257</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3258
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3259<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3260<p>The '<tt>urem</tt>' instruction returns the remainder from the unsigned
3261 division of its two arguments.</p>
3262
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3263<h5>Arguments:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3264<p>The two arguments to the '<tt>urem</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3265 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3266 values. Both arguments must have identical types.</p>
3267
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3268<h5>Semantics:</h5>
3269<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3270 This instruction always performs an unsigned division to get the
3271 remainder.</p>
3272
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3273<p>Note that unsigned integer remainder and signed integer remainder are
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3274 distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
3275
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3276<p>Taking the remainder of a division by zero leads to undefined behavior.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3277
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3278<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3279<pre>
3280 &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3281</pre>
3282
3283</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3284
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3285<!-- _______________________________________________________________________ -->
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3286<div class="doc_subsubsection">
3287 <a name="i_srem">'<tt>srem</tt>' Instruction</a>
3288</div>
3289
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3290<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3291
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3292<h5>Syntax:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3293<pre>
Gabor Greifd9068fe2008-08-07 21:46:00 +0000[diff] [blame]3294 &lt;result&gt; = srem &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3295</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3296
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3297<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3298<p>The '<tt>srem</tt>' instruction returns the remainder from the signed
3299 division of its two operands. This instruction can also take
3300 <a href="#t_vector">vector</a> versions of the values in which case the
3301 elements must be integers.</p>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]3302
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3303<h5>Arguments:</h5>
3304<p>The two arguments to the '<tt>srem</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3305 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3306 values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3307
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3308<h5>Semantics:</h5>
3309<p>This instruction returns the <i>remainder</i> of a division (where the result
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3310 has the same sign as the dividend, <tt>op1</tt>), not the <i>modulo</i>
3311 operator (where the result has the same sign as the divisor, <tt>op2</tt>) of
3312 a value. For more information about the difference,
3313 see <a href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
3314 Math Forum</a>. For a table of how this is implemented in various languages,
3315 please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
3316 Wikipedia: modulo operation</a>.</p>
3317
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3318<p>Note that signed integer remainder and unsigned integer remainder are
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3319 distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
3320
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]3321<p>Taking the remainder of a division by zero leads to undefined behavior.
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3322 Overflow also leads to undefined behavior; this is a rare case, but can
3323 occur, for example, by taking the remainder of a 32-bit division of
3324 -2147483648 by -1. (The remainder doesn't actually overflow, but this rule
3325 lets srem be implemented using instructions that return both the result of
3326 the division and the remainder.)</p>
3327
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3328<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3329<pre>
3330 &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3331</pre>
3332
3333</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3334
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3335<!-- _______________________________________________________________________ -->
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3336<div class="doc_subsubsection">
3337 <a name="i_frem">'<tt>frem</tt>' Instruction</a> </div>
3338
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3339<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3340
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3341<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3342<pre>
3343 &lt;result&gt; = frem &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3344</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3345
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3346<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3347<p>The '<tt>frem</tt>' instruction returns the remainder from the division of
3348 its two operands.</p>
3349
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3350<h5>Arguments:</h5>
3351<p>The two arguments to the '<tt>frem</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3352 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
3353 floating point values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3354
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3355<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3356<p>This instruction returns the <i>remainder</i> of a division. The remainder
3357 has the same sign as the dividend.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3358
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3359<h5>Example:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3360<pre>
3361 &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3362</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3363
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3364</div>
3365
3366<!-- ======================================================================= -->
3367<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
3368Operations</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3369
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3370<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3371
3372<p>Bitwise binary operators are used to do various forms of bit-twiddling in a
3373 program. They are generally very efficient instructions and can commonly be
3374 strength reduced from other instructions. They require two operands of the
3375 same type, execute an operation on them, and produce a single value. The
3376 resulting value is the same type as its operands.</p>
3377
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3378</div>
3379
3380<!-- _______________________________________________________________________ -->
3381<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
3382Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3383
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3384<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3385
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3386<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3387<pre>
3388 &lt;result&gt; = shl &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3389</pre>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3390
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3391<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3392<p>The '<tt>shl</tt>' instruction returns the first operand shifted to the left
3393 a specified number of bits.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3394
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3395<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3396<p>Both arguments to the '<tt>shl</tt>' instruction must be the
3397 same <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
3398 integer type. '<tt>op2</tt>' is treated as an unsigned value.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3399
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3400<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3401<p>The value produced is <tt>op1</tt> * 2<sup><tt>op2</tt></sup> mod
3402 2<sup>n</sup>, where <tt>n</tt> is the width of the result. If <tt>op2</tt>
3403 is (statically or dynamically) negative or equal to or larger than the number
3404 of bits in <tt>op1</tt>, the result is undefined. If the arguments are
3405 vectors, each vector element of <tt>op1</tt> is shifted by the corresponding
3406 shift amount in <tt>op2</tt>.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3407
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3408<h5>Example:</h5>
3409<pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3410 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
3411 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
3412 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3413 &lt;result&gt; = shl i32 1, 32 <i>; undefined</i>
Mon P Wang9901e732008-12-09 05:46:39 +0000[diff] [blame]3414 &lt;result&gt; = shl &lt;2 x i32&gt; &lt; i32 1, i32 1&gt;, &lt; i32 1, i32 2&gt; <i>; yields: result=&lt;2 x i32&gt; &lt; i32 2, i32 4&gt;</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3415</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3416
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3417</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3418
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3419<!-- _______________________________________________________________________ -->
3420<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
3421Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3422
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3423<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3424
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3425<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3426<pre>
3427 &lt;result&gt; = lshr &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3428</pre>
3429
3430<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3431<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
3432 operand shifted to the right a specified number of bits with zero fill.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3433
3434<h5>Arguments:</h5>
3435<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3436 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3437 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3438
3439<h5>Semantics:</h5>
3440<p>This instruction always performs a logical shift right operation. The most
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3441 significant bits of the result will be filled with zero bits after the shift.
3442 If <tt>op2</tt> is (statically or dynamically) equal to or larger than the
3443 number of bits in <tt>op1</tt>, the result is undefined. If the arguments are
3444 vectors, each vector element of <tt>op1</tt> is shifted by the corresponding
3445 shift amount in <tt>op2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3446
3447<h5>Example:</h5>
3448<pre>
3449 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
3450 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
3451 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
3452 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3453 &lt;result&gt; = lshr i32 1, 32 <i>; undefined</i>
Mon P Wang9901e732008-12-09 05:46:39 +0000[diff] [blame]3454 &lt;result&gt; = lshr &lt;2 x i32&gt; &lt; i32 -2, i32 4&gt;, &lt; i32 1, i32 2&gt; <i>; yields: result=&lt;2 x i32&gt; &lt; i32 0x7FFFFFFF, i32 1&gt;</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3455</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3456
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3457</div>
3458
3459<!-- _______________________________________________________________________ -->
3460<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
3461Instruction</a> </div>
3462<div class="doc_text">
3463
3464<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3465<pre>
3466 &lt;result&gt; = ashr &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3467</pre>
3468
3469<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3470<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
3471 operand shifted to the right a specified number of bits with sign
3472 extension.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3473
3474<h5>Arguments:</h5>
3475<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3476 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3477 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3478
3479<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3480<p>This instruction always performs an arithmetic shift right operation, The
3481 most significant bits of the result will be filled with the sign bit
3482 of <tt>op1</tt>. If <tt>op2</tt> is (statically or dynamically) equal to or
3483 larger than the number of bits in <tt>op1</tt>, the result is undefined. If
3484 the arguments are vectors, each vector element of <tt>op1</tt> is shifted by
3485 the corresponding shift amount in <tt>op2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3486
3487<h5>Example:</h5>
3488<pre>
3489 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
3490 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
3491 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
3492 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]3493 &lt;result&gt; = ashr i32 1, 32 <i>; undefined</i>
Mon P Wang9901e732008-12-09 05:46:39 +0000[diff] [blame]3494 &lt;result&gt; = ashr &lt;2 x i32&gt; &lt; i32 -2, i32 4&gt;, &lt; i32 1, i32 3&gt; <i>; yields: result=&lt;2 x i32&gt; &lt; i32 -1, i32 0&gt;</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3495</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3496
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3497</div>
3498
3499<!-- _______________________________________________________________________ -->
3500<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
3501Instruction</a> </div>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3502
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3503<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3504
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3505<h5>Syntax:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3506<pre>
Gabor Greifd9068fe2008-08-07 21:46:00 +0000[diff] [blame]3507 &lt;result&gt; = and &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3508</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3509
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3510<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3511<p>The '<tt>and</tt>' instruction returns the bitwise logical and of its two
3512 operands.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3513
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3514<h5>Arguments:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3515<p>The two arguments to the '<tt>and</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3516 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3517 values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3518
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3519<h5>Semantics:</h5>
3520<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3521
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3522<table border="1" cellspacing="0" cellpadding="4">
3523 <tbody>
3524 <tr>
3525 <td>In0</td>
3526 <td>In1</td>
3527 <td>Out</td>
3528 </tr>
3529 <tr>
3530 <td>0</td>
3531 <td>0</td>
3532 <td>0</td>
3533 </tr>
3534 <tr>
3535 <td>0</td>
3536 <td>1</td>
3537 <td>0</td>
3538 </tr>
3539 <tr>
3540 <td>1</td>
3541 <td>0</td>
3542 <td>0</td>
3543 </tr>
3544 <tr>
3545 <td>1</td>
3546 <td>1</td>
3547 <td>1</td>
3548 </tr>
3549 </tbody>
3550</table>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3551
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3552<h5>Example:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3553<pre>
3554 &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3555 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
3556 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
3557</pre>
3558</div>
3559<!-- _______________________________________________________________________ -->
3560<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3561
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3562<div class="doc_text">
3563
3564<h5>Syntax:</h5>
3565<pre>
3566 &lt;result&gt; = or &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
3567</pre>
3568
3569<h5>Overview:</h5>
3570<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive or of its
3571 two operands.</p>
3572
3573<h5>Arguments:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3574<p>The two arguments to the '<tt>or</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3575 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3576 values. Both arguments must have identical types.</p>
3577
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3578<h5>Semantics:</h5>
3579<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3580
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3581<table border="1" cellspacing="0" cellpadding="4">
3582 <tbody>
3583 <tr>
3584 <td>In0</td>
3585 <td>In1</td>
3586 <td>Out</td>
3587 </tr>
3588 <tr>
3589 <td>0</td>
3590 <td>0</td>
3591 <td>0</td>
3592 </tr>
3593 <tr>
3594 <td>0</td>
3595 <td>1</td>
3596 <td>1</td>
3597 </tr>
3598 <tr>
3599 <td>1</td>
3600 <td>0</td>
3601 <td>1</td>
3602 </tr>
3603 <tr>
3604 <td>1</td>
3605 <td>1</td>
3606 <td>1</td>
3607 </tr>
3608 </tbody>
3609</table>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3610
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3611<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3612<pre>
3613 &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3614 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
3615 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
3616</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3617
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3618</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3619
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3620<!-- _______________________________________________________________________ -->
3621<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
3622Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3623
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3624<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3625
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3626<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3627<pre>
3628 &lt;result&gt; = xor &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {ty}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3629</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3630
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3631<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3632<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive or of
3633 its two operands. The <tt>xor</tt> is used to implement the "one's
3634 complement" operation, which is the "~" operator in C.</p>
3635
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3636<h5>Arguments:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3637<p>The two arguments to the '<tt>xor</tt>' instruction must be
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3638 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3639 values. Both arguments must have identical types.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]3640
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3641<h5>Semantics:</h5>
3642<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3643
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3644<table border="1" cellspacing="0" cellpadding="4">
3645 <tbody>
3646 <tr>
3647 <td>In0</td>
3648 <td>In1</td>
3649 <td>Out</td>
3650 </tr>
3651 <tr>
3652 <td>0</td>
3653 <td>0</td>
3654 <td>0</td>
3655 </tr>
3656 <tr>
3657 <td>0</td>
3658 <td>1</td>
3659 <td>1</td>
3660 </tr>
3661 <tr>
3662 <td>1</td>
3663 <td>0</td>
3664 <td>1</td>
3665 </tr>
3666 <tr>
3667 <td>1</td>
3668 <td>1</td>
3669 <td>0</td>
3670 </tr>
3671 </tbody>
3672</table>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3673
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3674<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3675<pre>
3676 &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3677 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
3678 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
3679 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
3680</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3681
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3682</div>
3683
3684<!-- ======================================================================= -->
3685<div class="doc_subsection">
3686 <a name="vectorops">Vector Operations</a>
3687</div>
3688
3689<div class="doc_text">
3690
3691<p>LLVM supports several instructions to represent vector operations in a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3692 target-independent manner. These instructions cover the element-access and
3693 vector-specific operations needed to process vectors effectively. While LLVM
3694 does directly support these vector operations, many sophisticated algorithms
3695 will want to use target-specific intrinsics to take full advantage of a
3696 specific target.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3697
3698</div>
3699
3700<!-- _______________________________________________________________________ -->
3701<div class="doc_subsubsection">
3702 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
3703</div>
3704
3705<div class="doc_text">
3706
3707<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3708<pre>
3709 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
3710</pre>
3711
3712<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3713<p>The '<tt>extractelement</tt>' instruction extracts a single scalar element
3714 from a vector at a specified index.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3715
3716
3717<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3718<p>The first operand of an '<tt>extractelement</tt>' instruction is a value
3719 of <a href="#t_vector">vector</a> type. The second operand is an index
3720 indicating the position from which to extract the element. The index may be
3721 a variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3722
3723<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3724<p>The result is a scalar of the same type as the element type of
3725 <tt>val</tt>. Its value is the value at position <tt>idx</tt> of
3726 <tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
3727 results are undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3728
3729<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3730<pre>
3731 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
3732</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3733
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3734</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3735
3736<!-- _______________________________________________________________________ -->
3737<div class="doc_subsubsection">
3738 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
3739</div>
3740
3741<div class="doc_text">
3742
3743<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3744<pre>
Dan Gohmanbcc3c502008-05-12 23:38:42 +0000[diff] [blame]3745 &lt;result&gt; = insertelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, &lt;ty&gt; &lt;elt&gt;, i32 &lt;idx&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3746</pre>
3747
3748<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3749<p>The '<tt>insertelement</tt>' instruction inserts a scalar element into a
3750 vector at a specified index.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3751
3752<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3753<p>The first operand of an '<tt>insertelement</tt>' instruction is a value
3754 of <a href="#t_vector">vector</a> type. The second operand is a scalar value
3755 whose type must equal the element type of the first operand. The third
3756 operand is an index indicating the position at which to insert the value.
3757 The index may be a variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3758
3759<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3760<p>The result is a vector of the same type as <tt>val</tt>. Its element values
3761 are those of <tt>val</tt> except at position <tt>idx</tt>, where it gets the
3762 value <tt>elt</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
3763 results are undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3764
3765<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3766<pre>
3767 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
3768</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3769
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3770</div>
3771
3772<!-- _______________________________________________________________________ -->
3773<div class="doc_subsubsection">
3774 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
3775</div>
3776
3777<div class="doc_text">
3778
3779<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3780<pre>
Mon P Wangbff5d9c2008-11-10 04:46:22 +0000[diff] [blame]3781 &lt;result&gt; = shufflevector &lt;n x &lt;ty&gt;&gt; &lt;v1&gt;, &lt;n x &lt;ty&gt;&gt; &lt;v2&gt;, &lt;m x i32&gt; &lt;mask&gt; <i>; yields &lt;m x &lt;ty&gt;&gt;</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3782</pre>
3783
3784<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3785<p>The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
3786 from two input vectors, returning a vector with the same element type as the
3787 input and length that is the same as the shuffle mask.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3788
3789<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3790<p>The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
3791 with types that match each other. The third argument is a shuffle mask whose
3792 element type is always 'i32'. The result of the instruction is a vector
3793 whose length is the same as the shuffle mask and whose element type is the
3794 same as the element type of the first two operands.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3795
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3796<p>The shuffle mask operand is required to be a constant vector with either
3797 constant integer or undef values.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3798
3799<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3800<p>The elements of the two input vectors are numbered from left to right across
3801 both of the vectors. The shuffle mask operand specifies, for each element of
3802 the result vector, which element of the two input vectors the result element
3803 gets. The element selector may be undef (meaning "don't care") and the
3804 second operand may be undef if performing a shuffle from only one vector.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3805
3806<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3807<pre>
3808 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
3809 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
3810 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
3811 &lt;4 x i32&gt; &lt;i32 0, i32 1, i32 2, i32 3&gt; <i>; yields &lt;4 x i32&gt;</i> - Identity shuffle.
Mon P Wangbff5d9c2008-11-10 04:46:22 +0000[diff] [blame]3812 %result = shufflevector &lt;8 x i32&gt; %v1, &lt;8 x i32&gt; undef,
3813 &lt;4 x i32&gt; &lt;i32 0, i32 1, i32 2, i32 3&gt; <i>; yields &lt;4 x i32&gt;</i>
3814 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
3815 &lt;8 x i32&gt; &lt;i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7 &gt; <i>; yields &lt;8 x i32&gt;</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3816</pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3817
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3818</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3819
3820<!-- ======================================================================= -->
3821<div class="doc_subsection">
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3822 <a name="aggregateops">Aggregate Operations</a>
3823</div>
3824
3825<div class="doc_text">
3826
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3827<p>LLVM supports several instructions for working with aggregate values.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3828
3829</div>
3830
3831<!-- _______________________________________________________________________ -->
3832<div class="doc_subsubsection">
3833 <a name="i_extractvalue">'<tt>extractvalue</tt>' Instruction</a>
3834</div>
3835
3836<div class="doc_text">
3837
3838<h5>Syntax:</h5>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3839<pre>
3840 &lt;result&gt; = extractvalue &lt;aggregate type&gt; &lt;val&gt;, &lt;idx&gt;{, &lt;idx&gt;}*
3841</pre>
3842
3843<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3844<p>The '<tt>extractvalue</tt>' instruction extracts the value of a struct field
3845 or array element from an aggregate value.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3846
3847<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3848<p>The first operand of an '<tt>extractvalue</tt>' instruction is a value
3849 of <a href="#t_struct">struct</a> or <a href="#t_array">array</a> type. The
3850 operands are constant indices to specify which value to extract in a similar
3851 manner as indices in a
3852 '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3853
3854<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3855<p>The result is the value at the position in the aggregate specified by the
3856 index operands.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3857
3858<h5>Example:</h5>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3859<pre>
Dan Gohmane5febe42008-05-31 00:58:22 +0000[diff] [blame]3860 %result = extractvalue {i32, float} %agg, 0 <i>; yields i32</i>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3861</pre>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3862
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3863</div>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3864
3865<!-- _______________________________________________________________________ -->
3866<div class="doc_subsubsection">
3867 <a name="i_insertvalue">'<tt>insertvalue</tt>' Instruction</a>
3868</div>
3869
3870<div class="doc_text">
3871
3872<h5>Syntax:</h5>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3873<pre>
Dan Gohmane5febe42008-05-31 00:58:22 +0000[diff] [blame]3874 &lt;result&gt; = insertvalue &lt;aggregate type&gt; &lt;val&gt;, &lt;ty&gt; &lt;val&gt;, &lt;idx&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3875</pre>
3876
3877<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3878<p>The '<tt>insertvalue</tt>' instruction inserts a value into a struct field or
3879 array element in an aggregate.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3880
3881
3882<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3883<p>The first operand of an '<tt>insertvalue</tt>' instruction is a value
3884 of <a href="#t_struct">struct</a> or <a href="#t_array">array</a> type. The
3885 second operand is a first-class value to insert. The following operands are
3886 constant indices indicating the position at which to insert the value in a
3887 similar manner as indices in a
3888 '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction. The
3889 value to insert must have the same type as the value identified by the
3890 indices.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3891
3892<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3893<p>The result is an aggregate of the same type as <tt>val</tt>. Its value is
3894 that of <tt>val</tt> except that the value at the position specified by the
3895 indices is that of <tt>elt</tt>.</p>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3896
3897<h5>Example:</h5>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3898<pre>
Dan Gohmanb1aab4e2008-06-23 15:26:37 +0000[diff] [blame]3899 %result = insertvalue {i32, float} %agg, i32 1, 0 <i>; yields {i32, float}</i>
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3900</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3901
Dan Gohman74d6faf2008-05-12 23:51:09 +0000[diff] [blame]3902</div>
3903
3904
3905<!-- ======================================================================= -->
3906<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3907 <a name="memoryops">Memory Access and Addressing Operations</a>
3908</div>
3909
3910<div class="doc_text">
3911
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3912<p>A key design point of an SSA-based representation is how it represents
3913 memory. In LLVM, no memory locations are in SSA form, which makes things
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]3914 very simple. This section describes how to read, write, and allocate
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3915 memory in LLVM.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3916
3917</div>
3918
3919<!-- _______________________________________________________________________ -->
3920<div class="doc_subsubsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3921 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
3922</div>
3923
3924<div class="doc_text">
3925
3926<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3927<pre>
3928 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
3929</pre>
3930
3931<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3932<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3933 currently executing function, to be automatically released when this function
3934 returns to its caller. The object is always allocated in the generic address
3935 space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3936
3937<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3938<p>The '<tt>alloca</tt>' instruction
3939 allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt> bytes of memory on the
3940 runtime stack, returning a pointer of the appropriate type to the program.
3941 If "NumElements" is specified, it is the number of elements allocated,
3942 otherwise "NumElements" is defaulted to be one. If a constant alignment is
3943 specified, the value result of the allocation is guaranteed to be aligned to
3944 at least that boundary. If not specified, or if zero, the target can choose
3945 to align the allocation on any convenient boundary compatible with the
3946 type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3947
3948<p>'<tt>type</tt>' may be any sized type.</p>
3949
3950<h5>Semantics:</h5>
Bill Wendling2a454572009-05-08 20:49:29 +0000[diff] [blame]3951<p>Memory is allocated; a pointer is returned. The operation is undefined if
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3952 there is insufficient stack space for the allocation. '<tt>alloca</tt>'d
3953 memory is automatically released when the function returns. The
3954 '<tt>alloca</tt>' instruction is commonly used to represent automatic
3955 variables that must have an address available. When the function returns
3956 (either with the <tt><a href="#i_ret">ret</a></tt>
3957 or <tt><a href="#i_unwind">unwind</a></tt> instructions), the memory is
3958 reclaimed. Allocating zero bytes is legal, but the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3959
3960<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3961<pre>
Dan Gohmanf54f50a2009-01-04 23:49:44 +0000[diff] [blame]3962 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
3963 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
3964 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
3965 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3966</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3967
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3968</div>
3969
3970<!-- _______________________________________________________________________ -->
3971<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
3972Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3973
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3974<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3975
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3976<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3977<pre>
3978 &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]
3979 &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]
3980</pre>
3981
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3982<h5>Overview:</h5>
3983<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3984
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3985<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]3986<p>The argument to the '<tt>load</tt>' instruction specifies the memory address
3987 from which to load. The pointer must point to
3988 a <a href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
3989 marked as <tt>volatile</tt>, then the optimizer is not allowed to modify the
3990 number or order of execution of this <tt>load</tt> with other
3991 volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
3992 instructions. </p>
3993
3994<p>The optional constant "align" argument specifies the alignment of the
3995 operation (that is, the alignment of the memory address). A value of 0 or an
3996 omitted "align" argument means that the operation has the preferential
3997 alignment for the target. It is the responsibility of the code emitter to
3998 ensure that the alignment information is correct. Overestimating the
3999 alignment results in an undefined behavior. Underestimating the alignment may
4000 produce less efficient code. An alignment of 1 is always safe.</p>
4001
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4002<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4003<p>The location of memory pointed to is loaded. If the value being loaded is of
4004 scalar type then the number of bytes read does not exceed the minimum number
4005 of bytes needed to hold all bits of the type. For example, loading an
4006 <tt>i24</tt> reads at most three bytes. When loading a value of a type like
4007 <tt>i20</tt> with a size that is not an integral number of bytes, the result
4008 is undefined if the value was not originally written using a store of the
4009 same type.</p>
4010
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4011<h5>Examples:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4012<pre>
4013 %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
4014 <a href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4015 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
4016</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4017
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4018</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4019
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4020<!-- _______________________________________________________________________ -->
4021<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
4022Instruction</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4023
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4024<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4025
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4026<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4027<pre>
4028 store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4029 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
4030</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4031
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4032<h5>Overview:</h5>
4033<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4034
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4035<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4036<p>There are two arguments to the '<tt>store</tt>' instruction: a value to store
4037 and an address at which to store it. The type of the
4038 '<tt>&lt;pointer&gt;</tt>' operand must be a pointer to
4039 the <a href="#t_firstclass">first class</a> type of the
4040 '<tt>&lt;value&gt;</tt>' operand. If the <tt>store</tt> is marked
4041 as <tt>volatile</tt>, then the optimizer is not allowed to modify the number
4042 or order of execution of this <tt>store</tt> with other
4043 volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
4044 instructions.</p>
4045
4046<p>The optional constant "align" argument specifies the alignment of the
4047 operation (that is, the alignment of the memory address). A value of 0 or an
4048 omitted "align" argument means that the operation has the preferential
4049 alignment for the target. It is the responsibility of the code emitter to
4050 ensure that the alignment information is correct. Overestimating the
4051 alignment results in an undefined behavior. Underestimating the alignment may
4052 produce less efficient code. An alignment of 1 is always safe.</p>
4053
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4054<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4055<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>' at the
4056 location specified by the '<tt>&lt;pointer&gt;</tt>' operand. If
4057 '<tt>&lt;value&gt;</tt>' is of scalar type then the number of bytes written
4058 does not exceed the minimum number of bytes needed to hold all bits of the
4059 type. For example, storing an <tt>i24</tt> writes at most three bytes. When
4060 writing a value of a type like <tt>i20</tt> with a size that is not an
4061 integral number of bytes, it is unspecified what happens to the extra bits
4062 that do not belong to the type, but they will typically be overwritten.</p>
4063
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4064<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4065<pre>
4066 %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Bill Wendling63ffa142007-10-22 05:10:05 +0000[diff] [blame]4067 store i32 3, i32* %ptr <i>; yields {void}</i>
4068 %val = <a href="#i_load">load</a> i32* %ptr <i>; yields {i32}:val = i32 3</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4069</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4070
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4071</div>
4072
4073<!-- _______________________________________________________________________ -->
4074<div class="doc_subsubsection">
4075 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
4076</div>
4077
4078<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4079
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4080<h5>Syntax:</h5>
4081<pre>
Matthijs Kooijman32a080e2008-10-13 13:44:15 +0000[diff] [blame]4082 &lt;result&gt; = getelementptr &lt;pty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
Dan Gohman106b2ae2009-07-27 21:53:46 +0000[diff] [blame]4083 &lt;result&gt; = getelementptr inbounds &lt;pty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4084</pre>
4085
4086<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4087<p>The '<tt>getelementptr</tt>' instruction is used to get the address of a
4088 subelement of an aggregate data structure. It performs address calculation
4089 only and does not access memory.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4090
4091<h5>Arguments:</h5>
Matthijs Kooijman32a080e2008-10-13 13:44:15 +0000[diff] [blame]4092<p>The first argument is always a pointer, and forms the basis of the
Chris Lattnere92fc832009-07-29 06:44:13 +0000[diff] [blame]4093 calculation. The remaining arguments are indices that indicate which of the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4094 elements of the aggregate object are indexed. The interpretation of each
4095 index is dependent on the type being indexed into. The first index always
4096 indexes the pointer value given as the first argument, the second index
4097 indexes a value of the type pointed to (not necessarily the value directly
4098 pointed to, since the first index can be non-zero), etc. The first type
4099 indexed into must be a pointer value, subsequent types can be arrays, vectors
4100 and structs. Note that subsequent types being indexed into can never be
4101 pointers, since that would require loading the pointer before continuing
4102 calculation.</p>
Matthijs Kooijman32a080e2008-10-13 13:44:15 +0000[diff] [blame]4103
4104<p>The type of each index argument depends on the type it is indexing into.
Chris Lattnere92fc832009-07-29 06:44:13 +0000[diff] [blame]4105 When indexing into a (optionally packed) structure, only <tt>i32</tt> integer
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4106 <b>constants</b> are allowed. When indexing into an array, pointer or
Chris Lattnere92fc832009-07-29 06:44:13 +0000[diff] [blame]4107 vector, integers of any width are allowed, and they are not required to be
4108 constant.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4109
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4110<p>For example, let's consider a C code fragment and how it gets compiled to
4111 LLVM:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4112
4113<div class="doc_code">
4114<pre>
4115struct RT {
4116 char A;
4117 int B[10][20];
4118 char C;
4119};
4120struct ST {
4121 int X;
4122 double Y;
4123 struct RT Z;
4124};
4125
4126int *foo(struct ST *s) {
4127 return &amp;s[1].Z.B[5][13];
4128}
4129</pre>
4130</div>
4131
4132<p>The LLVM code generated by the GCC frontend is:</p>
4133
4134<div class="doc_code">
4135<pre>
Chris Lattner5b6dc6e2009-01-11 20:53:49 +0000[diff] [blame]4136%RT = <a href="#namedtypes">type</a> { i8 , [10 x [20 x i32]], i8 }
4137%ST = <a href="#namedtypes">type</a> { i32, double, %RT }
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4138
Dan Gohman47360842009-07-25 02:23:48 +0000[diff] [blame]4139define i32* @foo(%ST* %s) {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4140entry:
4141 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
4142 ret i32* %reg
4143}
4144</pre>
4145</div>
4146
4147<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4148<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4149 type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
4150 }</tt>' type, a structure. The second index indexes into the third element
4151 of the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
4152 i8 }</tt>' type, another structure. The third index indexes into the second
4153 element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
4154 array. The two dimensions of the array are subscripted into, yielding an
4155 '<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a
4156 pointer to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4157
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4158<p>Note that it is perfectly legal to index partially through a structure,
4159 returning a pointer to an inner element. Because of this, the LLVM code for
4160 the given testcase is equivalent to:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4161
4162<pre>
Dan Gohman47360842009-07-25 02:23:48 +0000[diff] [blame]4163 define i32* @foo(%ST* %s) {
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4164 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
4165 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
4166 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
4167 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
4168 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
4169 ret i32* %t5
4170 }
4171</pre>
4172
Dan Gohman106b2ae2009-07-27 21:53:46 +0000[diff] [blame]4173<p>If the <tt>inbounds</tt> keyword is present, the result value of the
Dan Gohman4cba1562009-07-29 16:00:30 +0000[diff] [blame]4174 <tt>getelementptr</tt> is undefined if the base pointer is not an
4175 <i>in bounds</i> address of an allocated object, or if any of the addresses
Dan Gohmanbc4c87f2009-08-20 17:08:17 +0000[diff] [blame]4176 that would be formed by successive addition of the offsets implied by the
4177 indices to the base address with infinitely precise arithmetic are not an
4178 <i>in bounds</i> address of that allocated object.
Dan Gohman4cba1562009-07-29 16:00:30 +0000[diff] [blame]4179 The <i>in bounds</i> addresses for an allocated object are all the addresses
Dan Gohmanbc4c87f2009-08-20 17:08:17 +0000[diff] [blame]4180 that point into the object, plus the address one byte past the end.</p>
Dan Gohman106b2ae2009-07-27 21:53:46 +0000[diff] [blame]4181
4182<p>If the <tt>inbounds</tt> keyword is not present, the offsets are added to
4183 the base address with silently-wrapping two's complement arithmetic, and
4184 the result value of the <tt>getelementptr</tt> may be outside the object
4185 pointed to by the base pointer. The result value may not necessarily be
4186 used to access memory though, even if it happens to point into allocated
4187 storage. See the <a href="#pointeraliasing">Pointer Aliasing Rules</a>
4188 section for more information.</p>
4189
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4190<p>The getelementptr instruction is often confusing. For some more insight into
4191 how it works, see <a href="GetElementPtr.html">the getelementptr FAQ</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4192
4193<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4194<pre>
4195 <i>; yields [12 x i8]*:aptr</i>
Matthijs Kooijman32a080e2008-10-13 13:44:15 +0000[diff] [blame]4196 %aptr = getelementptr {i32, [12 x i8]}* %saptr, i64 0, i32 1
4197 <i>; yields i8*:vptr</i>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]4198 %vptr = getelementptr {i32, &lt;2 x i8&gt;}* %svptr, i64 0, i32 1, i32 1
Matthijs Kooijman32a080e2008-10-13 13:44:15 +0000[diff] [blame]4199 <i>; yields i8*:eptr</i>
4200 %eptr = getelementptr [12 x i8]* %aptr, i64 0, i32 1
Sanjiv Gupta4f9a0dc2009-04-25 07:27:44 +0000[diff] [blame]4201 <i>; yields i32*:iptr</i>
Sanjiv Gupta1e46c582009-04-24 16:38:13 +0000[diff] [blame]4202 %iptr = getelementptr [10 x i32]* @arr, i16 0, i16 0
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4203</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4204
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4205</div>
4206
4207<!-- ======================================================================= -->
4208<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
4209</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4210
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4211<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4212
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4213<p>The instructions in this category are the conversion instructions (casting)
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4214 which all take a single operand and a type. They perform various bit
4215 conversions on the operand.</p>
4216
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4217</div>
4218
4219<!-- _______________________________________________________________________ -->
4220<div class="doc_subsubsection">
4221 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
4222</div>
4223<div class="doc_text">
4224
4225<h5>Syntax:</h5>
4226<pre>
4227 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4228</pre>
4229
4230<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4231<p>The '<tt>trunc</tt>' instruction truncates its operand to the
4232 type <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4233
4234<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4235<p>The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
4236 be an <a href="#t_integer">integer</a> type, and a type that specifies the
4237 size and type of the result, which must be
4238 an <a href="#t_integer">integer</a> type. The bit size of <tt>value</tt> must
4239 be larger than the bit size of <tt>ty2</tt>. Equal sized types are not
4240 allowed.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4241
4242<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4243<p>The '<tt>trunc</tt>' instruction truncates the high order bits
4244 in <tt>value</tt> and converts the remaining bits to <tt>ty2</tt>. Since the
4245 source size must be larger than the destination size, <tt>trunc</tt> cannot
4246 be a <i>no-op cast</i>. It will always truncate bits.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4247
4248<h5>Example:</h5>
4249<pre>
4250 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
4251 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
4252 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
4253</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4254
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4255</div>
4256
4257<!-- _______________________________________________________________________ -->
4258<div class="doc_subsubsection">
4259 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
4260</div>
4261<div class="doc_text">
4262
4263<h5>Syntax:</h5>
4264<pre>
4265 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4266</pre>
4267
4268<h5>Overview:</h5>
4269<p>The '<tt>zext</tt>' instruction zero extends its operand to type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4270 <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4271
4272
4273<h5>Arguments:</h5>
4274<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4275 <a href="#t_integer">integer</a> type, and a type to cast it to, which must
4276 also be of <a href="#t_integer">integer</a> type. The bit size of the
4277 <tt>value</tt> must be smaller than the bit size of the destination type,
4278 <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4279
4280<h5>Semantics:</h5>
4281<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4282 bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4283
4284<p>When zero extending from i1, the result will always be either 0 or 1.</p>
4285
4286<h5>Example:</h5>
4287<pre>
4288 %X = zext i32 257 to i64 <i>; yields i64:257</i>
4289 %Y = zext i1 true to i32 <i>; yields i32:1</i>
4290</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4291
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4292</div>
4293
4294<!-- _______________________________________________________________________ -->
4295<div class="doc_subsubsection">
4296 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
4297</div>
4298<div class="doc_text">
4299
4300<h5>Syntax:</h5>
4301<pre>
4302 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4303</pre>
4304
4305<h5>Overview:</h5>
4306<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
4307
4308<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4309<p>The '<tt>sext</tt>' instruction takes a value to cast, which must be of
4310 <a href="#t_integer">integer</a> type, and a type to cast it to, which must
4311 also be of <a href="#t_integer">integer</a> type. The bit size of the
4312 <tt>value</tt> must be smaller than the bit size of the destination type,
4313 <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4314
4315<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4316<p>The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
4317 bit (highest order bit) of the <tt>value</tt> until it reaches the bit size
4318 of the type <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4319
4320<p>When sign extending from i1, the extension always results in -1 or 0.</p>
4321
4322<h5>Example:</h5>
4323<pre>
4324 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
4325 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
4326</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4327
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4328</div>
4329
4330<!-- _______________________________________________________________________ -->
4331<div class="doc_subsubsection">
4332 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
4333</div>
4334
4335<div class="doc_text">
4336
4337<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4338<pre>
4339 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4340</pre>
4341
4342<h5>Overview:</h5>
4343<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4344 <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4345
4346<h5>Arguments:</h5>
4347<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4348 point</a> value to cast and a <a href="#t_floating">floating point</a> type
4349 to cast it to. The size of <tt>value</tt> must be larger than the size of
4350 <tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
4351 <i>no-op cast</i>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4352
4353<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4354<p>The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
4355 <a href="#t_floating">floating point</a> type to a smaller
4356 <a href="#t_floating">floating point</a> type. If the value cannot fit
4357 within the destination type, <tt>ty2</tt>, then the results are
4358 undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4359
4360<h5>Example:</h5>
4361<pre>
4362 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
4363 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
4364</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4365
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4366</div>
4367
4368<!-- _______________________________________________________________________ -->
4369<div class="doc_subsubsection">
4370 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
4371</div>
4372<div class="doc_text">
4373
4374<h5>Syntax:</h5>
4375<pre>
4376 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4377</pre>
4378
4379<h5>Overview:</h5>
4380<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4381 floating point value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4382
4383<h5>Arguments:</h5>
4384<p>The '<tt>fpext</tt>' instruction takes a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4385 <a href="#t_floating">floating point</a> <tt>value</tt> to cast, and
4386 a <a href="#t_floating">floating point</a> type to cast it to. The source
4387 type must be smaller than the destination type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4388
4389<h5>Semantics:</h5>
4390<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4391 <a href="#t_floating">floating point</a> type to a larger
4392 <a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
4393 used to make a <i>no-op cast</i> because it always changes bits. Use
4394 <tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4395
4396<h5>Example:</h5>
4397<pre>
4398 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
4399 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
4400</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4401
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4402</div>
4403
4404<!-- _______________________________________________________________________ -->
4405<div class="doc_subsubsection">
4406 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
4407</div>
4408<div class="doc_text">
4409
4410<h5>Syntax:</h5>
4411<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]4412 &lt;result&gt; = fptoui &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4413</pre>
4414
4415<h5>Overview:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]4416<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4417 unsigned integer equivalent of type <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4418
4419<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4420<p>The '<tt>fptoui</tt>' instruction takes a value to cast, which must be a
4421 scalar or vector <a href="#t_floating">floating point</a> value, and a type
4422 to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
4423 type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
4424 vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4425
4426<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4427<p>The '<tt>fptoui</tt>' instruction converts its
4428 <a href="#t_floating">floating point</a> operand into the nearest (rounding
4429 towards zero) unsigned integer value. If the value cannot fit
4430 in <tt>ty2</tt>, the results are undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4431
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4432<h5>Example:</h5>
4433<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]4434 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]4435 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]4436 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4437</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4438
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4439</div>
4440
4441<!-- _______________________________________________________________________ -->
4442<div class="doc_subsubsection">
4443 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
4444</div>
4445<div class="doc_text">
4446
4447<h5>Syntax:</h5>
4448<pre>
4449 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4450</pre>
4451
4452<h5>Overview:</h5>
4453<p>The '<tt>fptosi</tt>' instruction converts
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4454 <a href="#t_floating">floating point</a> <tt>value</tt> to
4455 type <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4456
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4457<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4458<p>The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
4459 scalar or vector <a href="#t_floating">floating point</a> value, and a type
4460 to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
4461 type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
4462 vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4463
4464<h5>Semantics:</h5>
4465<p>The '<tt>fptosi</tt>' instruction converts its
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4466 <a href="#t_floating">floating point</a> operand into the nearest (rounding
4467 towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
4468 the results are undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4469
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4470<h5>Example:</h5>
4471<pre>
4472 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]4473 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4474 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
4475</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4476
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4477</div>
4478
4479<!-- _______________________________________________________________________ -->
4480<div class="doc_subsubsection">
4481 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
4482</div>
4483<div class="doc_text">
4484
4485<h5>Syntax:</h5>
4486<pre>
4487 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4488</pre>
4489
4490<h5>Overview:</h5>
4491<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4492 integer and converts that value to the <tt>ty2</tt> type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4493
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4494<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]4495<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4496 scalar or vector <a href="#t_integer">integer</a> value, and a type to cast
4497 it to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
4498 type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
4499 floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4500
4501<h5>Semantics:</h5>
4502<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4503 integer quantity and converts it to the corresponding floating point
4504 value. If the value cannot fit in the floating point value, the results are
4505 undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4506
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4507<h5>Example:</h5>
4508<pre>
4509 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]4510 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4511</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4512
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4513</div>
4514
4515<!-- _______________________________________________________________________ -->
4516<div class="doc_subsubsection">
4517 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
4518</div>
4519<div class="doc_text">
4520
4521<h5>Syntax:</h5>
4522<pre>
4523 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4524</pre>
4525
4526<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4527<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed integer
4528 and converts that value to the <tt>ty2</tt> type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4529
4530<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]4531<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4532 scalar or vector <a href="#t_integer">integer</a> value, and a type to cast
4533 it to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
4534 type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
4535 floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4536
4537<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4538<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed integer
4539 quantity and converts it to the corresponding floating point value. If the
4540 value cannot fit in the floating point value, the results are undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4541
4542<h5>Example:</h5>
4543<pre>
4544 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]4545 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4546</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4547
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4548</div>
4549
4550<!-- _______________________________________________________________________ -->
4551<div class="doc_subsubsection">
4552 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
4553</div>
4554<div class="doc_text">
4555
4556<h5>Syntax:</h5>
4557<pre>
4558 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4559</pre>
4560
4561<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4562<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
4563 the integer type <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4564
4565<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4566<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
4567 must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
4568 <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4569
4570<h5>Semantics:</h5>
4571<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4572 <tt>ty2</tt> by interpreting the pointer value as an integer and either
4573 truncating or zero extending that value to the size of the integer type. If
4574 <tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
4575 <tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
4576 are the same size, then nothing is done (<i>no-op cast</i>) other than a type
4577 change.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4578
4579<h5>Example:</h5>
4580<pre>
4581 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
4582 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
4583</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4584
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4585</div>
4586
4587<!-- _______________________________________________________________________ -->
4588<div class="doc_subsubsection">
4589 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
4590</div>
4591<div class="doc_text">
4592
4593<h5>Syntax:</h5>
4594<pre>
4595 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4596</pre>
4597
4598<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4599<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to a
4600 pointer type, <tt>ty2</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4601
4602<h5>Arguments:</h5>
4603<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4604 value to cast, and a type to cast it to, which must be a
4605 <a href="#t_pointer">pointer</a> type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4606
4607<h5>Semantics:</h5>
4608<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4609 <tt>ty2</tt> by applying either a zero extension or a truncation depending on
4610 the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
4611 size of a pointer then a truncation is done. If <tt>value</tt> is smaller
4612 than the size of a pointer then a zero extension is done. If they are the
4613 same size, nothing is done (<i>no-op cast</i>).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4614
4615<h5>Example:</h5>
4616<pre>
4617 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
4618 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
4619 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
4620</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4621
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4622</div>
4623
4624<!-- _______________________________________________________________________ -->
4625<div class="doc_subsubsection">
4626 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
4627</div>
4628<div class="doc_text">
4629
4630<h5>Syntax:</h5>
4631<pre>
4632 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
4633</pre>
4634
4635<h5>Overview:</h5>
4636<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4637 <tt>ty2</tt> without changing any bits.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4638
4639<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4640<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be a
4641 non-aggregate first class value, and a type to cast it to, which must also be
4642 a non-aggregate <a href="#t_firstclass">first class</a> type. The bit sizes
4643 of <tt>value</tt> and the destination type, <tt>ty2</tt>, must be
4644 identical. If the source type is a pointer, the destination type must also be
4645 a pointer. This instruction supports bitwise conversion of vectors to
4646 integers and to vectors of other types (as long as they have the same
4647 size).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4648
4649<h5>Semantics:</h5>
4650<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4651 <tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
4652 this conversion. The conversion is done as if the <tt>value</tt> had been
4653 stored to memory and read back as type <tt>ty2</tt>. Pointer types may only
4654 be converted to other pointer types with this instruction. To convert
4655 pointers to other types, use the <a href="#i_inttoptr">inttoptr</a> or
4656 <a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4657
4658<h5>Example:</h5>
4659<pre>
4660 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
4661 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]4662 %Z = bitcast &lt;2 x int&gt; %V to i64; <i>; yields i64: %V</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4663</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4664
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4665</div>
4666
4667<!-- ======================================================================= -->
4668<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4669
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4670<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4671
4672<p>The instructions in this category are the "miscellaneous" instructions, which
4673 defy better classification.</p>
4674
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4675</div>
4676
4677<!-- _______________________________________________________________________ -->
4678<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
4679</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4680
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4681<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4682
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4683<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4684<pre>
4685 &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {i1} or {&lt;N x i1&gt;}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4686</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4687
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4688<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4689<p>The '<tt>icmp</tt>' instruction returns a boolean value or a vector of
4690 boolean values based on comparison of its two integer, integer vector, or
4691 pointer operands.</p>
4692
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4693<h5>Arguments:</h5>
4694<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4695 the condition code indicating the kind of comparison to perform. It is not a
4696 value, just a keyword. The possible condition code are:</p>
4697
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4698<ol>
4699 <li><tt>eq</tt>: equal</li>
4700 <li><tt>ne</tt>: not equal </li>
4701 <li><tt>ugt</tt>: unsigned greater than</li>
4702 <li><tt>uge</tt>: unsigned greater or equal</li>
4703 <li><tt>ult</tt>: unsigned less than</li>
4704 <li><tt>ule</tt>: unsigned less or equal</li>
4705 <li><tt>sgt</tt>: signed greater than</li>
4706 <li><tt>sge</tt>: signed greater or equal</li>
4707 <li><tt>slt</tt>: signed less than</li>
4708 <li><tt>sle</tt>: signed less or equal</li>
4709</ol>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4710
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4711<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4712 <a href="#t_pointer">pointer</a> or integer <a href="#t_vector">vector</a>
4713 typed. They must also be identical types.</p>
4714
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4715<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4716<p>The '<tt>icmp</tt>' compares <tt>op1</tt> and <tt>op2</tt> according to the
4717 condition code given as <tt>cond</tt>. The comparison performed always yields
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]4718 either an <a href="#t_integer"><tt>i1</tt></a> or vector of <tt>i1</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4719 result, as follows:</p>
4720
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4721<ol>
4722 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4723 <tt>false</tt> otherwise. No sign interpretation is necessary or
4724 performed.</li>
4725
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4726 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4727 <tt>false</tt> otherwise. No sign interpretation is necessary or
4728 performed.</li>
4729
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4730 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4731 <tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
4732
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4733 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4734 <tt>true</tt> if <tt>op1</tt> is greater than or equal
4735 to <tt>op2</tt>.</li>
4736
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4737 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4738 <tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
4739
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4740 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4741 <tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4742
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4743 <li><tt>sgt</tt>: interprets the operands as signed values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4744 <tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
4745
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4746 <li><tt>sge</tt>: interprets the operands as signed values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4747 <tt>true</tt> if <tt>op1</tt> is greater than or equal
4748 to <tt>op2</tt>.</li>
4749
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4750 <li><tt>slt</tt>: interprets the operands as signed values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4751 <tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
4752
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4753 <li><tt>sle</tt>: interprets the operands as signed values and yields
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4754 <tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4755</ol>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4756
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4757<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4758 values are compared as if they were integers.</p>
4759
4760<p>If the operands are integer vectors, then they are compared element by
4761 element. The result is an <tt>i1</tt> vector with the same number of elements
4762 as the values being compared. Otherwise, the result is an <tt>i1</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4763
4764<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4765<pre>
4766 &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4767 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
4768 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
4769 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
4770 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
4771 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
4772</pre>
Dan Gohmana53eb382009-01-22 01:39:38 +0000[diff] [blame]4773
4774<p>Note that the code generator does not yet support vector types with
4775 the <tt>icmp</tt> instruction.</p>
4776
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4777</div>
4778
4779<!-- _______________________________________________________________________ -->
4780<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
4781</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4782
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4783<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4784
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4785<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4786<pre>
4787 &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;op1&gt;, &lt;op2&gt; <i>; yields {i1} or {&lt;N x i1&gt;}:result</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4788</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4789
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4790<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4791<p>The '<tt>fcmp</tt>' instruction returns a boolean value or vector of boolean
4792 values based on comparison of its operands.</p>
4793
4794<p>If the operands are floating point scalars, then the result type is a boolean
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]4795(<a href="#t_integer"><tt>i1</tt></a>).</p>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4796
4797<p>If the operands are floating point vectors, then the result type is a vector
4798 of boolean with the same number of elements as the operands being
4799 compared.</p>
4800
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4801<h5>Arguments:</h5>
4802<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4803 the condition code indicating the kind of comparison to perform. It is not a
4804 value, just a keyword. The possible condition code are:</p>
4805
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4806<ol>
4807 <li><tt>false</tt>: no comparison, always returns false</li>
4808 <li><tt>oeq</tt>: ordered and equal</li>
4809 <li><tt>ogt</tt>: ordered and greater than </li>
4810 <li><tt>oge</tt>: ordered and greater than or equal</li>
4811 <li><tt>olt</tt>: ordered and less than </li>
4812 <li><tt>ole</tt>: ordered and less than or equal</li>
4813 <li><tt>one</tt>: ordered and not equal</li>
4814 <li><tt>ord</tt>: ordered (no nans)</li>
4815 <li><tt>ueq</tt>: unordered or equal</li>
4816 <li><tt>ugt</tt>: unordered or greater than </li>
4817 <li><tt>uge</tt>: unordered or greater than or equal</li>
4818 <li><tt>ult</tt>: unordered or less than </li>
4819 <li><tt>ule</tt>: unordered or less than or equal</li>
4820 <li><tt>une</tt>: unordered or not equal</li>
4821 <li><tt>uno</tt>: unordered (either nans)</li>
4822 <li><tt>true</tt>: no comparison, always returns true</li>
4823</ol>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4824
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4825<p><i>Ordered</i> means that neither operand is a QNAN while
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4826 <i>unordered</i> means that either operand may be a QNAN.</p>
4827
4828<p>Each of <tt>val1</tt> and <tt>val2</tt> arguments must be either
4829 a <a href="#t_floating">floating point</a> type or
4830 a <a href="#t_vector">vector</a> of floating point type. They must have
4831 identical types.</p>
4832
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4833<h5>Semantics:</h5>
Gabor Greifd9068fe2008-08-07 21:46:00 +0000[diff] [blame]4834<p>The '<tt>fcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4835 according to the condition code given as <tt>cond</tt>. If the operands are
4836 vectors, then the vectors are compared element by element. Each comparison
Nick Lewycky244cf482009-09-27 00:45:11 +0000[diff] [blame]4837 performed always yields an <a href="#t_integer">i1</a> result, as
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4838 follows:</p>
4839
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4840<ol>
4841 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4842
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4843 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4844 <tt>op1</tt> is equal to <tt>op2</tt>.</li>
4845
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4846 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4847 <tt>op1</tt> is greather than <tt>op2</tt>.</li>
4848
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4849 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4850 <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
4851
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4852 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4853 <tt>op1</tt> is less than <tt>op2</tt>.</li>
4854
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4855 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4856 <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4857
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4858 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4859 <tt>op1</tt> is not equal to <tt>op2</tt>.</li>
4860
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4861 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4862
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4863 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4864 <tt>op1</tt> is equal to <tt>op2</tt>.</li>
4865
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4866 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4867 <tt>op1</tt> is greater than <tt>op2</tt>.</li>
4868
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4869 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4870 <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
4871
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4872 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4873 <tt>op1</tt> is less than <tt>op2</tt>.</li>
4874
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4875 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4876 <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4877
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4878 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4879 <tt>op1</tt> is not equal to <tt>op2</tt>.</li>
4880
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4881 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4882
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4883 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
4884</ol>
4885
4886<h5>Example:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4887<pre>
4888 &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
Dan Gohmanb60ca3c2008-09-09 01:02:47 +0000[diff] [blame]4889 &lt;result&gt; = fcmp one float 4.0, 5.0 <i>; yields: result=true</i>
4890 &lt;result&gt; = fcmp olt float 4.0, 5.0 <i>; yields: result=true</i>
4891 &lt;result&gt; = fcmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4892</pre>
Dan Gohmana53eb382009-01-22 01:39:38 +0000[diff] [blame]4893
4894<p>Note that the code generator does not yet support vector types with
4895 the <tt>fcmp</tt> instruction.</p>
4896
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4897</div>
4898
4899<!-- _______________________________________________________________________ -->
Nate Begeman646fa482008-05-12 19:01:56 +0000[diff] [blame]4900<div class="doc_subsubsection">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4901 <a name="i_phi">'<tt>phi</tt>' Instruction</a>
4902</div>
4903
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4904<div class="doc_text">
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4905
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4906<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4907<pre>
4908 &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...
4909</pre>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4910
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4911<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4912<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in the
4913 SSA graph representing the function.</p>
4914
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4915<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4916<p>The type of the incoming values is specified with the first type field. After
4917 this, the '<tt>phi</tt>' instruction takes a list of pairs as arguments, with
4918 one pair for each predecessor basic block of the current block. Only values
4919 of <a href="#t_firstclass">first class</a> type may be used as the value
4920 arguments to the PHI node. Only labels may be used as the label
4921 arguments.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4922
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4923<p>There must be no non-phi instructions between the start of a basic block and
4924 the PHI instructions: i.e. PHI instructions must be first in a basic
4925 block.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4926
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4927<p>For the purposes of the SSA form, the use of each incoming value is deemed to
4928 occur on the edge from the corresponding predecessor block to the current
4929 block (but after any definition of an '<tt>invoke</tt>' instruction's return
4930 value on the same edge).</p>
Jay Foad8e2fd2c2009-06-03 10:20:10 +0000[diff] [blame]4931
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4932<h5>Semantics:</h5>
4933<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4934 specified by the pair corresponding to the predecessor basic block that
4935 executed just prior to the current block.</p>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4936
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4937<h5>Example:</h5>
Chris Lattner6704c212008-05-20 20:48:21 +0000[diff] [blame]4938<pre>
4939Loop: ; Infinite loop that counts from 0 on up...
4940 %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
4941 %nextindvar = add i32 %indvar, 1
4942 br label %Loop
4943</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4944
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4945</div>
4946
4947<!-- _______________________________________________________________________ -->
4948<div class="doc_subsubsection">
4949 <a name="i_select">'<tt>select</tt>' Instruction</a>
4950</div>
4951
4952<div class="doc_text">
4953
4954<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4955<pre>
Dan Gohmanb60ca3c2008-09-09 01:02:47 +0000[diff] [blame]4956 &lt;result&gt; = select <i>selty</i> &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
4957
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]4958 <i>selty</i> is either i1 or {&lt;N x i1&gt;}
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4959</pre>
4960
4961<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4962<p>The '<tt>select</tt>' instruction is used to choose one value based on a
4963 condition, without branching.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4964
4965
4966<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4967<p>The '<tt>select</tt>' instruction requires an 'i1' value or a vector of 'i1'
4968 values indicating the condition, and two values of the
4969 same <a href="#t_firstclass">first class</a> type. If the val1/val2 are
4970 vectors and the condition is a scalar, then entire vectors are selected, not
4971 individual elements.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4972
4973<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4974<p>If the condition is an i1 and it evaluates to 1, the instruction returns the
4975 first value argument; otherwise, it returns the second value argument.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4976
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]4977<p>If the condition is a vector of i1, then the value arguments must be vectors
4978 of the same size, and the selection is done element by element.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4979
4980<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4981<pre>
4982 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
4983</pre>
Dan Gohmana53eb382009-01-22 01:39:38 +0000[diff] [blame]4984
4985<p>Note that the code generator does not yet support conditions
4986 with vector type.</p>
4987
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4988</div>
4989
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4990<!-- _______________________________________________________________________ -->
4991<div class="doc_subsubsection">
4992 <a name="i_call">'<tt>call</tt>' Instruction</a>
4993</div>
4994
4995<div class="doc_text">
4996
4997<h5>Syntax:</h5>
4998<pre>
Devang Pateld0bfcc72008-10-07 17:48:33 +0000[diff] [blame]4999 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] &lt;ty&gt; [&lt;fnty&gt;*] &lt;fnptrval&gt;(&lt;function args&gt;) [<a href="#fnattrs">fn attrs</a>]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5000</pre>
5001
5002<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5003<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
5004
5005<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5006<p>This instruction requires several arguments:</p>
5007
5008<ol>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5009 <li>The optional "tail" marker indicates whether the callee function accesses
5010 any allocas or varargs in the caller. If the "tail" marker is present,
5011 the function call is eligible for tail call optimization. Note that calls
5012 may be marked "tail" even if they do not occur before
5013 a <a href="#i_ret"><tt>ret</tt></a> instruction.</li>
Devang Patelac2fc272008-10-06 18:50:38 +0000[diff] [blame]5014
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5015 <li>The optional "cconv" marker indicates which <a href="#callingconv">calling
5016 convention</a> the call should use. If none is specified, the call
5017 defaults to using C calling conventions.</li>
Devang Patelac2fc272008-10-06 18:50:38 +0000[diff] [blame]5018
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5019 <li>The optional <a href="#paramattrs">Parameter Attributes</a> list for
5020 return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>', and
5021 '<tt>inreg</tt>' attributes are valid here.</li>
5022
5023 <li>'<tt>ty</tt>': the type of the call instruction itself which is also the
5024 type of the return value. Functions that return no value are marked
5025 <tt><a href="#t_void">void</a></tt>.</li>
5026
5027 <li>'<tt>fnty</tt>': shall be the signature of the pointer to function value
5028 being invoked. The argument types must match the types implied by this
5029 signature. This type can be omitted if the function is not varargs and if
5030 the function type does not return a pointer to a function.</li>
5031
5032 <li>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
5033 be invoked. In most cases, this is a direct function invocation, but
5034 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
5035 to function value.</li>
5036
5037 <li>'<tt>function args</tt>': argument list whose types match the function
5038 signature argument types. All arguments must be of
5039 <a href="#t_firstclass">first class</a> type. If the function signature
5040 indicates the function accepts a variable number of arguments, the extra
5041 arguments can be specified.</li>
5042
5043 <li>The optional <a href="#fnattrs">function attributes</a> list. Only
5044 '<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
5045 '<tt>readnone</tt>' attributes are valid here.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5046</ol>
5047
5048<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5049<p>The '<tt>call</tt>' instruction is used to cause control flow to transfer to
5050 a specified function, with its incoming arguments bound to the specified
5051 values. Upon a '<tt><a href="#i_ret">ret</a></tt>' instruction in the called
5052 function, control flow continues with the instruction after the function
5053 call, and the return value of the function is bound to the result
5054 argument.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5055
5056<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5057<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]5058 %retval = call i32 @test(i32 %argc)
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]5059 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42) <i>; yields i32</i>
5060 %X = tail call i32 @foo() <i>; yields i32</i>
5061 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
5062 call void %foo(i8 97 signext)
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]5063
5064 %struct.A = type { i32, i8 }
Devang Patelac2fc272008-10-06 18:50:38 +0000[diff] [blame]5065 %r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
Dan Gohman3e700032008-10-04 19:00:07 +0000[diff] [blame]5066 %gr = extractvalue %struct.A %r, 0 <i>; yields i32</i>
5067 %gr1 = extractvalue %struct.A %r, 1 <i>; yields i8</i>
Chris Lattnerac454b32008-10-08 06:26:11 +0000[diff] [blame]5068 %Z = call void @foo() noreturn <i>; indicates that %foo never returns normally</i>
Matthijs Kooijman2c4e05a2008-10-07 10:03:45 +0000[diff] [blame]5069 %ZZ = call zeroext i32 @bar() <i>; Return value is %zero extended</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5070</pre>
5071
Dale Johannesen9fcf4a92009-09-24 18:38:21 +0000[diff] [blame]5072<p>llvm treats calls to some functions with names and arguments that match the
Dale Johannesen4730cd32009-09-25 17:04:42 +0000[diff] [blame]5073standard C99 library as being the C99 library functions, and may perform
5074optimizations or generate code for them under that assumption. This is
5075something we'd like to change in the future to provide better support for
5076freestanding environments and non-C-based langauges.</p>
Dale Johannesen9fcf4a92009-09-24 18:38:21 +0000[diff] [blame]5077
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5078</div>
5079
5080<!-- _______________________________________________________________________ -->
5081<div class="doc_subsubsection">
5082 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
5083</div>
5084
5085<div class="doc_text">
5086
5087<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5088<pre>
5089 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
5090</pre>
5091
5092<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5093<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5094 the "variable argument" area of a function call. It is used to implement the
5095 <tt>va_arg</tt> macro in C.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5096
5097<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5098<p>This instruction takes a <tt>va_list*</tt> value and the type of the
5099 argument. It returns a value of the specified argument type and increments
5100 the <tt>va_list</tt> to point to the next argument. The actual type
5101 of <tt>va_list</tt> is target specific.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5102
5103<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5104<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified type
5105 from the specified <tt>va_list</tt> and causes the <tt>va_list</tt> to point
5106 to the next argument. For more information, see the variable argument
5107 handling <a href="#int_varargs">Intrinsic Functions</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5108
5109<p>It is legal for this instruction to be called in a function which does not
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5110 take a variable number of arguments, for example, the <tt>vfprintf</tt>
5111 function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5112
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5113<p><tt>va_arg</tt> is an LLVM instruction instead of
5114 an <a href="#intrinsics">intrinsic function</a> because it takes a type as an
5115 argument.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5116
5117<h5>Example:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5118<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
5119
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5120<p>Note that the code generator does not yet fully support va_arg on many
5121 targets. Also, it does not currently support va_arg with aggregate types on
5122 any target.</p>
Dan Gohman60967192009-01-12 23:12:39 +0000[diff] [blame]5123
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5124</div>
5125
5126<!-- *********************************************************************** -->
5127<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
5128<!-- *********************************************************************** -->
5129
5130<div class="doc_text">
5131
5132<p>LLVM supports the notion of an "intrinsic function". These functions have
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5133 well known names and semantics and are required to follow certain
5134 restrictions. Overall, these intrinsics represent an extension mechanism for
5135 the LLVM language that does not require changing all of the transformations
5136 in LLVM when adding to the language (or the bitcode reader/writer, the
5137 parser, etc...).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5138
5139<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5140 prefix is reserved in LLVM for intrinsic names; thus, function names may not
5141 begin with this prefix. Intrinsic functions must always be external
5142 functions: you cannot define the body of intrinsic functions. Intrinsic
5143 functions may only be used in call or invoke instructions: it is illegal to
5144 take the address of an intrinsic function. Additionally, because intrinsic
5145 functions are part of the LLVM language, it is required if any are added that
5146 they be documented here.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5147
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5148<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents a
5149 family of functions that perform the same operation but on different data
5150 types. Because LLVM can represent over 8 million different integer types,
5151 overloading is used commonly to allow an intrinsic function to operate on any
5152 integer type. One or more of the argument types or the result type can be
5153 overloaded to accept any integer type. Argument types may also be defined as
5154 exactly matching a previous argument's type or the result type. This allows
5155 an intrinsic function which accepts multiple arguments, but needs all of them
5156 to be of the same type, to only be overloaded with respect to a single
5157 argument or the result.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5158
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5159<p>Overloaded intrinsics will have the names of its overloaded argument types
5160 encoded into its function name, each preceded by a period. Only those types
5161 which are overloaded result in a name suffix. Arguments whose type is matched
5162 against another type do not. For example, the <tt>llvm.ctpop</tt> function
5163 can take an integer of any width and returns an integer of exactly the same
5164 integer width. This leads to a family of functions such as
5165 <tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29
5166 %val)</tt>. Only one type, the return type, is overloaded, and only one type
5167 suffix is required. Because the argument's type is matched against the return
5168 type, it does not require its own name suffix.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5169
5170<p>To learn how to add an intrinsic function, please see the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5171 <a href="ExtendingLLVM.html">Extending LLVM Guide</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5172
5173</div>
5174
5175<!-- ======================================================================= -->
5176<div class="doc_subsection">
5177 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
5178</div>
5179
5180<div class="doc_text">
5181
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5182<p>Variable argument support is defined in LLVM with
5183 the <a href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
5184 intrinsic functions. These functions are related to the similarly named
5185 macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5186
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5187<p>All of these functions operate on arguments that use a target-specific value
5188 type "<tt>va_list</tt>". The LLVM assembly language reference manual does
5189 not define what this type is, so all transformations should be prepared to
5190 handle these functions regardless of the type used.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5191
5192<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5193 instruction and the variable argument handling intrinsic functions are
5194 used.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5195
5196<div class="doc_code">
5197<pre>
5198define i32 @test(i32 %X, ...) {
5199 ; Initialize variable argument processing
5200 %ap = alloca i8*
5201 %ap2 = bitcast i8** %ap to i8*
5202 call void @llvm.va_start(i8* %ap2)
5203
5204 ; Read a single integer argument
5205 %tmp = va_arg i8** %ap, i32
5206
5207 ; Demonstrate usage of llvm.va_copy and llvm.va_end
5208 %aq = alloca i8*
5209 %aq2 = bitcast i8** %aq to i8*
5210 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
5211 call void @llvm.va_end(i8* %aq2)
5212
5213 ; Stop processing of arguments.
5214 call void @llvm.va_end(i8* %ap2)
5215 ret i32 %tmp
5216}
5217
5218declare void @llvm.va_start(i8*)
5219declare void @llvm.va_copy(i8*, i8*)
5220declare void @llvm.va_end(i8*)
5221</pre>
5222</div>
5223
5224</div>
5225
5226<!-- _______________________________________________________________________ -->
5227<div class="doc_subsubsection">
5228 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
5229</div>
5230
5231
5232<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5233
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5234<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5235<pre>
5236 declare void %llvm.va_start(i8* &lt;arglist&gt;)
5237</pre>
5238
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5239<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5240<p>The '<tt>llvm.va_start</tt>' intrinsic initializes <tt>*&lt;arglist&gt;</tt>
5241 for subsequent use by <tt><a href="#i_va_arg">va_arg</a></tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5242
5243<h5>Arguments:</h5>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]5244<p>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5245
5246<h5>Semantics:</h5>
Dan Gohman2672f3e2008-10-14 16:51:45 +0000[diff] [blame]5247<p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5248 macro available in C. In a target-dependent way, it initializes
5249 the <tt>va_list</tt> element to which the argument points, so that the next
5250 call to <tt>va_arg</tt> will produce the first variable argument passed to
5251 the function. Unlike the C <tt>va_start</tt> macro, this intrinsic does not
5252 need to know the last argument of the function as the compiler can figure
5253 that out.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5254
5255</div>
5256
5257<!-- _______________________________________________________________________ -->
5258<div class="doc_subsubsection">
5259 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
5260</div>
5261
5262<div class="doc_text">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5263
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5264<h5>Syntax:</h5>
5265<pre>
5266 declare void @llvm.va_end(i8* &lt;arglist&gt;)
5267</pre>
5268
5269<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5270<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5271 which has been initialized previously
5272 with <tt><a href="#int_va_start">llvm.va_start</a></tt>
5273 or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5274
5275<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5276<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
5277
5278<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5279<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5280 macro available in C. In a target-dependent way, it destroys
5281 the <tt>va_list</tt> element to which the argument points. Calls
5282 to <a href="#int_va_start"><tt>llvm.va_start</tt></a>
5283 and <a href="#int_va_copy"> <tt>llvm.va_copy</tt></a> must be matched exactly
5284 with calls to <tt>llvm.va_end</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5285
5286</div>
5287
5288<!-- _______________________________________________________________________ -->
5289<div class="doc_subsubsection">
5290 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
5291</div>
5292
5293<div class="doc_text">
5294
5295<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5296<pre>
5297 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
5298</pre>
5299
5300<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5301<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5302 from the source argument list to the destination argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5303
5304<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5305<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5306 The second argument is a pointer to a <tt>va_list</tt> element to copy
5307 from.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5308
5309<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5310<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5311 macro available in C. In a target-dependent way, it copies the
5312 source <tt>va_list</tt> element into the destination <tt>va_list</tt>
5313 element. This intrinsic is necessary because
5314 the <tt><a href="#int_va_start"> llvm.va_start</a></tt> intrinsic may be
5315 arbitrarily complex and require, for example, memory allocation.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5316
5317</div>
5318
5319<!-- ======================================================================= -->
5320<div class="doc_subsection">
5321 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
5322</div>
5323
5324<div class="doc_text">
5325
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5326<p>LLVM support for <a href="GarbageCollection.html">Accurate Garbage
Chris Lattner96451482008-08-05 18:29:16 +0000[diff] [blame]5327Collection</a> (GC) requires the implementation and generation of these
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5328intrinsics. These intrinsics allow identification of <a href="#int_gcroot">GC
5329roots on the stack</a>, as well as garbage collector implementations that
5330require <a href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a>
5331barriers. Front-ends for type-safe garbage collected languages should generate
5332these intrinsics to make use of the LLVM garbage collectors. For more details,
5333see <a href="GarbageCollection.html">Accurate Garbage Collection with
5334LLVM</a>.</p>
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]5335
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5336<p>The garbage collection intrinsics only operate on objects in the generic
5337 address space (address space zero).</p>
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]5338
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5339</div>
5340
5341<!-- _______________________________________________________________________ -->
5342<div class="doc_subsubsection">
5343 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
5344</div>
5345
5346<div class="doc_text">
5347
5348<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5349<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5350 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5351</pre>
5352
5353<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5354<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5355 the code generator, and allows some metadata to be associated with it.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5356
5357<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5358<p>The first argument specifies the address of a stack object that contains the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5359 root pointer. The second pointer (which must be either a constant or a
5360 global value address) contains the meta-data to be associated with the
5361 root.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5362
5363<h5>Semantics:</h5>
Chris Lattnera7d94ba2008-04-24 05:59:56 +0000[diff] [blame]5364<p>At runtime, a call to this intrinsic stores a null pointer into the "ptrloc"
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5365 location. At compile-time, the code generator generates information to allow
5366 the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
5367 intrinsic may only be used in a function which <a href="#gc">specifies a GC
5368 algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5369
5370</div>
5371
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5372<!-- _______________________________________________________________________ -->
5373<div class="doc_subsubsection">
5374 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
5375</div>
5376
5377<div class="doc_text">
5378
5379<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5380<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5381 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5382</pre>
5383
5384<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5385<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5386 locations, allowing garbage collector implementations that require read
5387 barriers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5388
5389<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5390<p>The second argument is the address to read from, which should be an address
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5391 allocated from the garbage collector. The first object is a pointer to the
5392 start of the referenced object, if needed by the language runtime (otherwise
5393 null).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5394
5395<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5396<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5397 instruction, but may be replaced with substantially more complex code by the
5398 garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
5399 may only be used in a function which <a href="#gc">specifies a GC
5400 algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5401
5402</div>
5403
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5404<!-- _______________________________________________________________________ -->
5405<div class="doc_subsubsection">
5406 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
5407</div>
5408
5409<div class="doc_text">
5410
5411<h5>Syntax:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5412<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5413 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5414</pre>
5415
5416<h5>Overview:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5417<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5418 locations, allowing garbage collector implementations that require write
5419 barriers (such as generational or reference counting collectors).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5420
5421<h5>Arguments:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5422<p>The first argument is the reference to store, the second is the start of the
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5423 object to store it to, and the third is the address of the field of Obj to
5424 store to. If the runtime does not require a pointer to the object, Obj may
5425 be null.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5426
5427<h5>Semantics:</h5>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5428<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5429 instruction, but may be replaced with substantially more complex code by the
5430 garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
5431 may only be used in a function which <a href="#gc">specifies a GC
5432 algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5433
5434</div>
5435
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5436<!-- ======================================================================= -->
5437<div class="doc_subsection">
5438 <a name="int_codegen">Code Generator Intrinsics</a>
5439</div>
5440
5441<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5442
5443<p>These intrinsics are provided by LLVM to expose special features that may
5444 only be implemented with code generator support.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5445
5446</div>
5447
5448<!-- _______________________________________________________________________ -->
5449<div class="doc_subsubsection">
5450 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
5451</div>
5452
5453<div class="doc_text">
5454
5455<h5>Syntax:</h5>
5456<pre>
5457 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
5458</pre>
5459
5460<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5461<p>The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
5462 target-specific value indicating the return address of the current function
5463 or one of its callers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5464
5465<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5466<p>The argument to this intrinsic indicates which function to return the address
5467 for. Zero indicates the calling function, one indicates its caller, etc.
5468 The argument is <b>required</b> to be a constant integer value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5469
5470<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5471<p>The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer
5472 indicating the return address of the specified call frame, or zero if it
5473 cannot be identified. The value returned by this intrinsic is likely to be
5474 incorrect or 0 for arguments other than zero, so it should only be used for
5475 debugging purposes.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5476
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5477<p>Note that calling this intrinsic does not prevent function inlining or other
5478 aggressive transformations, so the value returned may not be that of the
5479 obvious source-language caller.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5480
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5481</div>
5482
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5483<!-- _______________________________________________________________________ -->
5484<div class="doc_subsubsection">
5485 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
5486</div>
5487
5488<div class="doc_text">
5489
5490<h5>Syntax:</h5>
5491<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5492 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5493</pre>
5494
5495<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5496<p>The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
5497 target-specific frame pointer value for the specified stack frame.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5498
5499<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5500<p>The argument to this intrinsic indicates which function to return the frame
5501 pointer for. Zero indicates the calling function, one indicates its caller,
5502 etc. The argument is <b>required</b> to be a constant integer value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5503
5504<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5505<p>The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer
5506 indicating the frame address of the specified call frame, or zero if it
5507 cannot be identified. The value returned by this intrinsic is likely to be
5508 incorrect or 0 for arguments other than zero, so it should only be used for
5509 debugging purposes.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5510
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5511<p>Note that calling this intrinsic does not prevent function inlining or other
5512 aggressive transformations, so the value returned may not be that of the
5513 obvious source-language caller.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5514
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5515</div>
5516
5517<!-- _______________________________________________________________________ -->
5518<div class="doc_subsubsection">
5519 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
5520</div>
5521
5522<div class="doc_text">
5523
5524<h5>Syntax:</h5>
5525<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5526 declare i8 *@llvm.stacksave()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5527</pre>
5528
5529<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5530<p>The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state
5531 of the function stack, for use
5532 with <a href="#int_stackrestore"> <tt>llvm.stackrestore</tt></a>. This is
5533 useful for implementing language features like scoped automatic variable
5534 sized arrays in C99.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5535
5536<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5537<p>This intrinsic returns a opaque pointer value that can be passed
5538 to <a href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When
5539 an <tt>llvm.stackrestore</tt> intrinsic is executed with a value saved
5540 from <tt>llvm.stacksave</tt>, it effectively restores the state of the stack
5541 to the state it was in when the <tt>llvm.stacksave</tt> intrinsic executed.
5542 In practice, this pops any <a href="#i_alloca">alloca</a> blocks from the
5543 stack that were allocated after the <tt>llvm.stacksave</tt> was executed.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5544
5545</div>
5546
5547<!-- _______________________________________________________________________ -->
5548<div class="doc_subsubsection">
5549 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
5550</div>
5551
5552<div class="doc_text">
5553
5554<h5>Syntax:</h5>
5555<pre>
5556 declare void @llvm.stackrestore(i8 * %ptr)
5557</pre>
5558
5559<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5560<p>The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
5561 the function stack to the state it was in when the
5562 corresponding <a href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic
5563 executed. This is useful for implementing language features like scoped
5564 automatic variable sized arrays in C99.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5565
5566<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5567<p>See the description
5568 for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5569
5570</div>
5571
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5572<!-- _______________________________________________________________________ -->
5573<div class="doc_subsubsection">
5574 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
5575</div>
5576
5577<div class="doc_text">
5578
5579<h5>Syntax:</h5>
5580<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5581 declare void @llvm.prefetch(i8* &lt;address&gt;, i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5582</pre>
5583
5584<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5585<p>The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to
5586 insert a prefetch instruction if supported; otherwise, it is a noop.
5587 Prefetches have no effect on the behavior of the program but can change its
5588 performance characteristics.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5589
5590<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5591<p><tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the
5592 specifier determining if the fetch should be for a read (0) or write (1),
5593 and <tt>locality</tt> is a temporal locality specifier ranging from (0) - no
5594 locality, to (3) - extremely local keep in cache. The <tt>rw</tt>
5595 and <tt>locality</tt> arguments must be constant integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5596
5597<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5598<p>This intrinsic does not modify the behavior of the program. In particular,
5599 prefetches cannot trap and do not produce a value. On targets that support
5600 this intrinsic, the prefetch can provide hints to the processor cache for
5601 better performance.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5602
5603</div>
5604
5605<!-- _______________________________________________________________________ -->
5606<div class="doc_subsubsection">
5607 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
5608</div>
5609
5610<div class="doc_text">
5611
5612<h5>Syntax:</h5>
5613<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]5614 declare void @llvm.pcmarker(i32 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5615</pre>
5616
5617<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5618<p>The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program
5619 Counter (PC) in a region of code to simulators and other tools. The method
5620 is target specific, but it is expected that the marker will use exported
5621 symbols to transmit the PC of the marker. The marker makes no guarantees
5622 that it will remain with any specific instruction after optimizations. It is
5623 possible that the presence of a marker will inhibit optimizations. The
5624 intended use is to be inserted after optimizations to allow correlations of
5625 simulation runs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5626
5627<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5628<p><tt>id</tt> is a numerical id identifying the marker.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5629
5630<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5631<p>This intrinsic does not modify the behavior of the program. Backends that do
5632 not support this intrinisic may ignore it.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5633
5634</div>
5635
5636<!-- _______________________________________________________________________ -->
5637<div class="doc_subsubsection">
5638 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
5639</div>
5640
5641<div class="doc_text">
5642
5643<h5>Syntax:</h5>
5644<pre>
5645 declare i64 @llvm.readcyclecounter( )
5646</pre>
5647
5648<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5649<p>The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
5650 counter register (or similar low latency, high accuracy clocks) on those
5651 targets that support it. On X86, it should map to RDTSC. On Alpha, it
5652 should map to RPCC. As the backing counters overflow quickly (on the order
5653 of 9 seconds on alpha), this should only be used for small timings.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5654
5655<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5656<p>When directly supported, reading the cycle counter should not modify any
5657 memory. Implementations are allowed to either return a application specific
5658 value or a system wide value. On backends without support, this is lowered
5659 to a constant 0.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5660
5661</div>
5662
5663<!-- ======================================================================= -->
5664<div class="doc_subsection">
5665 <a name="int_libc">Standard C Library Intrinsics</a>
5666</div>
5667
5668<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5669
5670<p>LLVM provides intrinsics for a few important standard C library functions.
5671 These intrinsics allow source-language front-ends to pass information about
5672 the alignment of the pointer arguments to the code generator, providing
5673 opportunity for more efficient code generation.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5674
5675</div>
5676
5677<!-- _______________________________________________________________________ -->
5678<div class="doc_subsubsection">
5679 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
5680</div>
5681
5682<div class="doc_text">
5683
5684<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5685<p>This is an overloaded intrinsic. You can use <tt>llvm.memcpy</tt> on any
5686 integer bit width. Not all targets support all bit widths however.</p>
5687
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5688<pre>
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5689 declare void @llvm.memcpy.i8(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5690 i8 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5691 declare void @llvm.memcpy.i16(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
5692 i16 &lt;len&gt;, i32 &lt;align&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5693 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
5694 i32 &lt;len&gt;, i32 &lt;align&gt;)
5695 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
5696 i64 &lt;len&gt;, i32 &lt;align&gt;)
5697</pre>
5698
5699<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5700<p>The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the
5701 source location to the destination location.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5702
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5703<p>Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
5704 intrinsics do not return a value, and takes an extra alignment argument.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5705
5706<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5707<p>The first argument is a pointer to the destination, the second is a pointer
5708 to the source. The third argument is an integer argument specifying the
5709 number of bytes to copy, and the fourth argument is the alignment of the
5710 source and destination locations.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5711
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5712<p>If the call to this intrinisic has an alignment value that is not 0 or 1,
5713 then the caller guarantees that both the source and destination pointers are
5714 aligned to that boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5715
5716<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5717<p>The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the
5718 source location to the destination location, which are not allowed to
5719 overlap. It copies "len" bytes of memory over. If the argument is known to
5720 be aligned to some boundary, this can be specified as the fourth argument,
5721 otherwise it should be set to 0 or 1.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5722
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5723</div>
5724
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5725<!-- _______________________________________________________________________ -->
5726<div class="doc_subsubsection">
5727 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
5728</div>
5729
5730<div class="doc_text">
5731
5732<h5>Syntax:</h5>
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5733<p>This is an overloaded intrinsic. You can use llvm.memmove on any integer bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5734 width. Not all targets support all bit widths however.</p>
5735
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5736<pre>
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5737 declare void @llvm.memmove.i8(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5738 i8 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5739 declare void @llvm.memmove.i16(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
5740 i16 &lt;len&gt;, i32 &lt;align&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5741 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
5742 i32 &lt;len&gt;, i32 &lt;align&gt;)
5743 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
5744 i64 &lt;len&gt;, i32 &lt;align&gt;)
5745</pre>
5746
5747<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5748<p>The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the
5749 source location to the destination location. It is similar to the
5750 '<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to
5751 overlap.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5752
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5753<p>Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
5754 intrinsics do not return a value, and takes an extra alignment argument.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5755
5756<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5757<p>The first argument is a pointer to the destination, the second is a pointer
5758 to the source. The third argument is an integer argument specifying the
5759 number of bytes to copy, and the fourth argument is the alignment of the
5760 source and destination locations.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5761
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5762<p>If the call to this intrinisic has an alignment value that is not 0 or 1,
5763 then the caller guarantees that the source and destination pointers are
5764 aligned to that boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5765
5766<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5767<p>The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the
5768 source location to the destination location, which may overlap. It copies
5769 "len" bytes of memory over. If the argument is known to be aligned to some
5770 boundary, this can be specified as the fourth argument, otherwise it should
5771 be set to 0 or 1.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5772
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5773</div>
5774
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5775<!-- _______________________________________________________________________ -->
5776<div class="doc_subsubsection">
5777 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
5778</div>
5779
5780<div class="doc_text">
5781
5782<h5>Syntax:</h5>
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5783<p>This is an overloaded intrinsic. You can use llvm.memset on any integer bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5784 width. Not all targets support all bit widths however.</p>
5785
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5786<pre>
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5787 declare void @llvm.memset.i8(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5788 i8 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner82c2e432008-11-21 16:42:48 +0000[diff] [blame]5789 declare void @llvm.memset.i16(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
5790 i16 &lt;len&gt;, i32 &lt;align&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5791 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
5792 i32 &lt;len&gt;, i32 &lt;align&gt;)
5793 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
5794 i64 &lt;len&gt;, i32 &lt;align&gt;)
5795</pre>
5796
5797<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5798<p>The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a
5799 particular byte value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5800
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5801<p>Note that, unlike the standard libc function, the <tt>llvm.memset</tt>
5802 intrinsic does not return a value, and takes an extra alignment argument.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5803
5804<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5805<p>The first argument is a pointer to the destination to fill, the second is the
5806 byte value to fill it with, the third argument is an integer argument
5807 specifying the number of bytes to fill, and the fourth argument is the known
5808 alignment of destination location.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5809
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5810<p>If the call to this intrinisic has an alignment value that is not 0 or 1,
5811 then the caller guarantees that the destination pointer is aligned to that
5812 boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5813
5814<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5815<p>The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting
5816 at the destination location. If the argument is known to be aligned to some
5817 boundary, this can be specified as the fourth argument, otherwise it should
5818 be set to 0 or 1.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5819
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5820</div>
5821
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5822<!-- _______________________________________________________________________ -->
5823<div class="doc_subsubsection">
5824 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
5825</div>
5826
5827<div class="doc_text">
5828
5829<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5830<p>This is an overloaded intrinsic. You can use <tt>llvm.sqrt</tt> on any
5831 floating point or vector of floating point type. Not all targets support all
5832 types however.</p>
5833
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5834<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]5835 declare float @llvm.sqrt.f32(float %Val)
5836 declare double @llvm.sqrt.f64(double %Val)
5837 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
5838 declare fp128 @llvm.sqrt.f128(fp128 %Val)
5839 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5840</pre>
5841
5842<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5843<p>The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
5844 returning the same value as the libm '<tt>sqrt</tt>' functions would.
5845 Unlike <tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined
5846 behavior for negative numbers other than -0.0 (which allows for better
5847 optimization, because there is no need to worry about errno being
5848 set). <tt>llvm.sqrt(-0.0)</tt> is defined to return -0.0 like IEEE sqrt.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5849
5850<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5851<p>The argument and return value are floating point numbers of the same
5852 type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5853
5854<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5855<p>This function returns the sqrt of the specified operand if it is a
5856 nonnegative floating point number.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5857
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5858</div>
5859
5860<!-- _______________________________________________________________________ -->
5861<div class="doc_subsubsection">
5862 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
5863</div>
5864
5865<div class="doc_text">
5866
5867<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5868<p>This is an overloaded intrinsic. You can use <tt>llvm.powi</tt> on any
5869 floating point or vector of floating point type. Not all targets support all
5870 types however.</p>
5871
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5872<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]5873 declare float @llvm.powi.f32(float %Val, i32 %power)
5874 declare double @llvm.powi.f64(double %Val, i32 %power)
5875 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
5876 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
5877 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5878</pre>
5879
5880<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5881<p>The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
5882 specified (positive or negative) power. The order of evaluation of
5883 multiplications is not defined. When a vector of floating point type is
5884 used, the second argument remains a scalar integer value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5885
5886<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5887<p>The second argument is an integer power, and the first is a value to raise to
5888 that power.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5889
5890<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5891<p>This function returns the first value raised to the second power with an
5892 unspecified sequence of rounding operations.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5893
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5894</div>
5895
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5896<!-- _______________________________________________________________________ -->
5897<div class="doc_subsubsection">
5898 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
5899</div>
5900
5901<div class="doc_text">
5902
5903<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5904<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
5905 floating point or vector of floating point type. Not all targets support all
5906 types however.</p>
5907
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5908<pre>
5909 declare float @llvm.sin.f32(float %Val)
5910 declare double @llvm.sin.f64(double %Val)
5911 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
5912 declare fp128 @llvm.sin.f128(fp128 %Val)
5913 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
5914</pre>
5915
5916<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5917<p>The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5918
5919<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5920<p>The argument and return value are floating point numbers of the same
5921 type.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5922
5923<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5924<p>This function returns the sine of the specified operand, returning the same
5925 values as the libm <tt>sin</tt> functions would, and handles error conditions
5926 in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5927
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5928</div>
5929
5930<!-- _______________________________________________________________________ -->
5931<div class="doc_subsubsection">
5932 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
5933</div>
5934
5935<div class="doc_text">
5936
5937<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5938<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
5939 floating point or vector of floating point type. Not all targets support all
5940 types however.</p>
5941
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5942<pre>
5943 declare float @llvm.cos.f32(float %Val)
5944 declare double @llvm.cos.f64(double %Val)
5945 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
5946 declare fp128 @llvm.cos.f128(fp128 %Val)
5947 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
5948</pre>
5949
5950<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5951<p>The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5952
5953<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5954<p>The argument and return value are floating point numbers of the same
5955 type.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5956
5957<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5958<p>This function returns the cosine of the specified operand, returning the same
5959 values as the libm <tt>cos</tt> functions would, and handles error conditions
5960 in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5961
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5962</div>
5963
5964<!-- _______________________________________________________________________ -->
5965<div class="doc_subsubsection">
5966 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
5967</div>
5968
5969<div class="doc_text">
5970
5971<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5972<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
5973 floating point or vector of floating point type. Not all targets support all
5974 types however.</p>
5975
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5976<pre>
5977 declare float @llvm.pow.f32(float %Val, float %Power)
5978 declare double @llvm.pow.f64(double %Val, double %Power)
5979 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
5980 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
5981 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
5982</pre>
5983
5984<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5985<p>The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
5986 specified (positive or negative) power.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5987
5988<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5989<p>The second argument is a floating point power, and the first is a value to
5990 raise to that power.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5991
5992<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]5993<p>This function returns the first value raised to the second power, returning
5994 the same values as the libm <tt>pow</tt> functions would, and handles error
5995 conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5996
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]5997</div>
5998
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5999<!-- ======================================================================= -->
6000<div class="doc_subsection">
6001 <a name="int_manip">Bit Manipulation Intrinsics</a>
6002</div>
6003
6004<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6005
6006<p>LLVM provides intrinsics for a few important bit manipulation operations.
6007 These allow efficient code generation for some algorithms.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6008
6009</div>
6010
6011<!-- _______________________________________________________________________ -->
6012<div class="doc_subsubsection">
6013 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
6014</div>
6015
6016<div class="doc_text">
6017
6018<h5>Syntax:</h5>
6019<p>This is an overloaded intrinsic function. You can use bswap on any integer
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6020 type that is an even number of bytes (i.e. BitWidth % 16 == 0).</p>
6021
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6022<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6023 declare i16 @llvm.bswap.i16(i16 &lt;id&gt;)
6024 declare i32 @llvm.bswap.i32(i32 &lt;id&gt;)
6025 declare i64 @llvm.bswap.i64(i64 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6026</pre>
6027
6028<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6029<p>The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
6030 values with an even number of bytes (positive multiple of 16 bits). These
6031 are useful for performing operations on data that is not in the target's
6032 native byte order.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6033
6034<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6035<p>The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
6036 and low byte of the input i16 swapped. Similarly,
6037 the <tt>llvm.bswap.i32</tt> intrinsic returns an i32 value that has the four
6038 bytes of the input i32 swapped, so that if the input bytes are numbered 0, 1,
6039 2, 3 then the returned i32 will have its bytes in 3, 2, 1, 0 order.
6040 The <tt>llvm.bswap.i48</tt>, <tt>llvm.bswap.i64</tt> and other intrinsics
6041 extend this concept to additional even-byte lengths (6 bytes, 8 bytes and
6042 more, respectively).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6043
6044</div>
6045
6046<!-- _______________________________________________________________________ -->
6047<div class="doc_subsubsection">
6048 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
6049</div>
6050
6051<div class="doc_text">
6052
6053<h5>Syntax:</h5>
6054<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6055 width. Not all targets support all bit widths however.</p>
6056
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6057<pre>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6058 declare i8 @llvm.ctpop.i8(i8 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6059 declare i16 @llvm.ctpop.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6060 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6061 declare i64 @llvm.ctpop.i64(i64 &lt;src&gt;)
6062 declare i256 @llvm.ctpop.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6063</pre>
6064
6065<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6066<p>The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set
6067 in a value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6068
6069<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6070<p>The only argument is the value to be counted. The argument may be of any
6071 integer type. The return type must match the argument type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6072
6073<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6074<p>The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6075
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6076</div>
6077
6078<!-- _______________________________________________________________________ -->
6079<div class="doc_subsubsection">
6080 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
6081</div>
6082
6083<div class="doc_text">
6084
6085<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6086<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
6087 integer bit width. Not all targets support all bit widths however.</p>
6088
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6089<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6090 declare i8 @llvm.ctlz.i8 (i8 &lt;src&gt;)
6091 declare i16 @llvm.ctlz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6092 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6093 declare i64 @llvm.ctlz.i64(i64 &lt;src&gt;)
6094 declare i256 @llvm.ctlz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6095</pre>
6096
6097<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6098<p>The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
6099 leading zeros in a variable.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6100
6101<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6102<p>The only argument is the value to be counted. The argument may be of any
6103 integer type. The return type must match the argument type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6104
6105<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6106<p>The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant)
6107 zeros in a variable. If the src == 0 then the result is the size in bits of
6108 the type of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6109
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6110</div>
6111
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6112<!-- _______________________________________________________________________ -->
6113<div class="doc_subsubsection">
6114 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
6115</div>
6116
6117<div class="doc_text">
6118
6119<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6120<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
6121 integer bit width. Not all targets support all bit widths however.</p>
6122
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6123<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6124 declare i8 @llvm.cttz.i8 (i8 &lt;src&gt;)
6125 declare i16 @llvm.cttz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6126 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]6127 declare i64 @llvm.cttz.i64(i64 &lt;src&gt;)
6128 declare i256 @llvm.cttz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6129</pre>
6130
6131<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6132<p>The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
6133 trailing zeros.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6134
6135<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6136<p>The only argument is the value to be counted. The argument may be of any
6137 integer type. The return type must match the argument type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6138
6139<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6140<p>The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant)
6141 zeros in a variable. If the src == 0 then the result is the size in bits of
6142 the type of src. For example, <tt>llvm.cttz(2) = 1</tt>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6143
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6144</div>
6145
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6146<!-- ======================================================================= -->
6147<div class="doc_subsection">
6148 <a name="int_overflow">Arithmetic with Overflow Intrinsics</a>
6149</div>
6150
6151<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6152
6153<p>LLVM provides intrinsics for some arithmetic with overflow operations.</p>
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6154
6155</div>
6156
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6157<!-- _______________________________________________________________________ -->
6158<div class="doc_subsubsection">
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6159 <a name="int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt>' Intrinsics</a>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6160</div>
6161
6162<div class="doc_text">
6163
6164<h5>Syntax:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6165<p>This is an overloaded intrinsic. You can use <tt>llvm.sadd.with.overflow</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6166 on any integer bit width.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6167
6168<pre>
6169 declare {i16, i1} @llvm.sadd.with.overflow.i16(i16 %a, i16 %b)
6170 declare {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
6171 declare {i64, i1} @llvm.sadd.with.overflow.i64(i64 %a, i64 %b)
6172</pre>
6173
6174<h5>Overview:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6175<p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6176 a signed addition of the two arguments, and indicate whether an overflow
6177 occurred during the signed summation.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6178
6179<h5>Arguments:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6180<p>The arguments (%a and %b) and the first element of the result structure may
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6181 be of integer types of any bit width, but they must have the same bit
6182 width. The second element of the result structure must be of
6183 type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
6184 undergo signed addition.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6185
6186<h5>Semantics:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6187<p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6188 a signed addition of the two variables. They return a structure &mdash; the
6189 first element of which is the signed summation, and the second element of
6190 which is a bit specifying if the signed summation resulted in an
6191 overflow.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6192
6193<h5>Examples:</h5>
6194<pre>
6195 %res = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
6196 %sum = extractvalue {i32, i1} %res, 0
6197 %obit = extractvalue {i32, i1} %res, 1
6198 br i1 %obit, label %overflow, label %normal
6199</pre>
6200
6201</div>
6202
6203<!-- _______________________________________________________________________ -->
6204<div class="doc_subsubsection">
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6205 <a name="int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt>' Intrinsics</a>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6206</div>
6207
6208<div class="doc_text">
6209
6210<h5>Syntax:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6211<p>This is an overloaded intrinsic. You can use <tt>llvm.uadd.with.overflow</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6212 on any integer bit width.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6213
6214<pre>
6215 declare {i16, i1} @llvm.uadd.with.overflow.i16(i16 %a, i16 %b)
6216 declare {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
6217 declare {i64, i1} @llvm.uadd.with.overflow.i64(i64 %a, i64 %b)
6218</pre>
6219
6220<h5>Overview:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6221<p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6222 an unsigned addition of the two arguments, and indicate whether a carry
6223 occurred during the unsigned summation.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6224
6225<h5>Arguments:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6226<p>The arguments (%a and %b) and the first element of the result structure may
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6227 be of integer types of any bit width, but they must have the same bit
6228 width. The second element of the result structure must be of
6229 type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
6230 undergo unsigned addition.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6231
6232<h5>Semantics:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6233<p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6234 an unsigned addition of the two arguments. They return a structure &mdash;
6235 the first element of which is the sum, and the second element of which is a
6236 bit specifying if the unsigned summation resulted in a carry.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6237
6238<h5>Examples:</h5>
6239<pre>
6240 %res = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
6241 %sum = extractvalue {i32, i1} %res, 0
6242 %obit = extractvalue {i32, i1} %res, 1
6243 br i1 %obit, label %carry, label %normal
6244</pre>
6245
6246</div>
6247
6248<!-- _______________________________________________________________________ -->
6249<div class="doc_subsubsection">
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6250 <a name="int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt>' Intrinsics</a>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6251</div>
6252
6253<div class="doc_text">
6254
6255<h5>Syntax:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6256<p>This is an overloaded intrinsic. You can use <tt>llvm.ssub.with.overflow</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6257 on any integer bit width.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6258
6259<pre>
6260 declare {i16, i1} @llvm.ssub.with.overflow.i16(i16 %a, i16 %b)
6261 declare {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
6262 declare {i64, i1} @llvm.ssub.with.overflow.i64(i64 %a, i64 %b)
6263</pre>
6264
6265<h5>Overview:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6266<p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6267 a signed subtraction of the two arguments, and indicate whether an overflow
6268 occurred during the signed subtraction.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6269
6270<h5>Arguments:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6271<p>The arguments (%a and %b) and the first element of the result structure may
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6272 be of integer types of any bit width, but they must have the same bit
6273 width. The second element of the result structure must be of
6274 type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
6275 undergo signed subtraction.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6276
6277<h5>Semantics:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6278<p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6279 a signed subtraction of the two arguments. They return a structure &mdash;
6280 the first element of which is the subtraction, and the second element of
6281 which is a bit specifying if the signed subtraction resulted in an
6282 overflow.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6283
6284<h5>Examples:</h5>
6285<pre>
6286 %res = call {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
6287 %sum = extractvalue {i32, i1} %res, 0
6288 %obit = extractvalue {i32, i1} %res, 1
6289 br i1 %obit, label %overflow, label %normal
6290</pre>
6291
6292</div>
6293
6294<!-- _______________________________________________________________________ -->
6295<div class="doc_subsubsection">
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6296 <a name="int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt>' Intrinsics</a>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6297</div>
6298
6299<div class="doc_text">
6300
6301<h5>Syntax:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6302<p>This is an overloaded intrinsic. You can use <tt>llvm.usub.with.overflow</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6303 on any integer bit width.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6304
6305<pre>
6306 declare {i16, i1} @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
6307 declare {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
6308 declare {i64, i1} @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
6309</pre>
6310
6311<h5>Overview:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6312<p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6313 an unsigned subtraction of the two arguments, and indicate whether an
6314 overflow occurred during the unsigned subtraction.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6315
6316<h5>Arguments:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6317<p>The arguments (%a and %b) and the first element of the result structure may
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6318 be of integer types of any bit width, but they must have the same bit
6319 width. The second element of the result structure must be of
6320 type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
6321 undergo unsigned subtraction.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6322
6323<h5>Semantics:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6324<p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6325 an unsigned subtraction of the two arguments. They return a structure &mdash;
6326 the first element of which is the subtraction, and the second element of
6327 which is a bit specifying if the unsigned subtraction resulted in an
6328 overflow.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6329
6330<h5>Examples:</h5>
6331<pre>
6332 %res = call {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
6333 %sum = extractvalue {i32, i1} %res, 0
6334 %obit = extractvalue {i32, i1} %res, 1
6335 br i1 %obit, label %overflow, label %normal
6336</pre>
6337
6338</div>
6339
6340<!-- _______________________________________________________________________ -->
6341<div class="doc_subsubsection">
Bill Wendling3e1258b2009-02-08 04:04:40 +0000[diff] [blame]6342 <a name="int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt>' Intrinsics</a>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6343</div>
6344
6345<div class="doc_text">
6346
6347<h5>Syntax:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6348<p>This is an overloaded intrinsic. You can use <tt>llvm.smul.with.overflow</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6349 on any integer bit width.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6350
6351<pre>
6352 declare {i16, i1} @llvm.smul.with.overflow.i16(i16 %a, i16 %b)
6353 declare {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
6354 declare {i64, i1} @llvm.smul.with.overflow.i64(i64 %a, i64 %b)
6355</pre>
6356
6357<h5>Overview:</h5>
6358
6359<p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6360 a signed multiplication of the two arguments, and indicate whether an
6361 overflow occurred during the signed multiplication.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6362
6363<h5>Arguments:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6364<p>The arguments (%a and %b) and the first element of the result structure may
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6365 be of integer types of any bit width, but they must have the same bit
6366 width. The second element of the result structure must be of
6367 type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
6368 undergo signed multiplication.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6369
6370<h5>Semantics:</h5>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6371<p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6372 a signed multiplication of the two arguments. They return a structure &mdash;
6373 the first element of which is the multiplication, and the second element of
6374 which is a bit specifying if the signed multiplication resulted in an
6375 overflow.</p>
Bill Wendling3f8cebe2009-02-08 01:40:31 +0000[diff] [blame]6376
6377<h5>Examples:</h5>
6378<pre>
6379 %res = call {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
6380 %sum = extractvalue {i32, i1} %res, 0
6381 %obit = extractvalue {i32, i1} %res, 1
6382 br i1 %obit, label %overflow, label %normal
6383</pre>
6384
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6385</div>
6386
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6387<!-- _______________________________________________________________________ -->
6388<div class="doc_subsubsection">
6389 <a name="int_umul_overflow">'<tt>llvm.umul.with.overflow.*</tt>' Intrinsics</a>
6390</div>
6391
6392<div class="doc_text">
6393
6394<h5>Syntax:</h5>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6395<p>This is an overloaded intrinsic. You can use <tt>llvm.umul.with.overflow</tt>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6396 on any integer bit width.</p>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6397
6398<pre>
6399 declare {i16, i1} @llvm.umul.with.overflow.i16(i16 %a, i16 %b)
6400 declare {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
6401 declare {i64, i1} @llvm.umul.with.overflow.i64(i64 %a, i64 %b)
6402</pre>
6403
6404<h5>Overview:</h5>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6405<p>The '<tt>llvm.umul.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6406 a unsigned multiplication of the two arguments, and indicate whether an
6407 overflow occurred during the unsigned multiplication.</p>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6408
6409<h5>Arguments:</h5>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6410<p>The arguments (%a and %b) and the first element of the result structure may
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6411 be of integer types of any bit width, but they must have the same bit
6412 width. The second element of the result structure must be of
6413 type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
6414 undergo unsigned multiplication.</p>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6415
6416<h5>Semantics:</h5>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6417<p>The '<tt>llvm.umul.with.overflow</tt>' family of intrinsic functions perform
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6418 an unsigned multiplication of the two arguments. They return a structure
6419 &mdash; the first element of which is the multiplication, and the second
6420 element of which is a bit specifying if the unsigned multiplication resulted
6421 in an overflow.</p>
Bill Wendlingbda98b62009-02-08 23:00:09 +0000[diff] [blame]6422
6423<h5>Examples:</h5>
6424<pre>
6425 %res = call {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
6426 %sum = extractvalue {i32, i1} %res, 0
6427 %obit = extractvalue {i32, i1} %res, 1
6428 br i1 %obit, label %overflow, label %normal
6429</pre>
6430
6431</div>
6432
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6433<!-- ======================================================================= -->
6434<div class="doc_subsection">
6435 <a name="int_debugger">Debugger Intrinsics</a>
6436</div>
6437
6438<div class="doc_text">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6439
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6440<p>The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt>
6441 prefix), are described in
6442 the <a href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source
6443 Level Debugging</a> document.</p>
6444
6445</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6446
6447<!-- ======================================================================= -->
6448<div class="doc_subsection">
6449 <a name="int_eh">Exception Handling Intrinsics</a>
6450</div>
6451
6452<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6453
6454<p>The LLVM exception handling intrinsics (which all start with
6455 <tt>llvm.eh.</tt> prefix), are described in
6456 the <a href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
6457 Handling</a> document.</p>
6458
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]6459</div>
6460
6461<!-- ======================================================================= -->
6462<div class="doc_subsection">
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]6463 <a name="int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6464</div>
6465
6466<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6467
6468<p>This intrinsic makes it possible to excise one parameter, marked with
6469 the <tt>nest</tt> attribute, from a function. The result is a callable
6470 function pointer lacking the nest parameter - the caller does not need to
6471 provide a value for it. Instead, the value to use is stored in advance in a
6472 "trampoline", a block of memory usually allocated on the stack, which also
6473 contains code to splice the nest value into the argument list. This is used
6474 to implement the GCC nested function address extension.</p>
6475
6476<p>For example, if the function is
6477 <tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function
6478 pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as
6479 follows:</p>
6480
6481<div class="doc_code">
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6482<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]6483 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
6484 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
6485 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
6486 %fp = bitcast i8* %p to i32 (i32, i32)*
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6487</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6488</div>
6489
6490<p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
6491 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
6492
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6493</div>
6494
6495<!-- _______________________________________________________________________ -->
6496<div class="doc_subsubsection">
6497 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
6498</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6499
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6500<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6501
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6502<h5>Syntax:</h5>
6503<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6504 declare i8* @llvm.init.trampoline(i8* &lt;tramp&gt;, i8* &lt;func&gt;, i8* &lt;nval&gt;)
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6505</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6506
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6507<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6508<p>This fills the memory pointed to by <tt>tramp</tt> with code and returns a
6509 function pointer suitable for executing it.</p>
6510
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6511<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6512<p>The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
6513 pointers. The <tt>tramp</tt> argument must point to a sufficiently large and
6514 sufficiently aligned block of memory; this memory is written to by the
6515 intrinsic. Note that the size and the alignment are target-specific - LLVM
6516 currently provides no portable way of determining them, so a front-end that
6517 generates this intrinsic needs to have some target-specific knowledge.
6518 The <tt>func</tt> argument must hold a function bitcast to
6519 an <tt>i8*</tt>.</p>
6520
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6521<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6522<p>The block of memory pointed to by <tt>tramp</tt> is filled with target
6523 dependent code, turning it into a function. A pointer to this function is
6524 returned, but needs to be bitcast to an <a href="#int_trampoline">appropriate
6525 function pointer type</a> before being called. The new function's signature
6526 is the same as that of <tt>func</tt> with any arguments marked with
6527 the <tt>nest</tt> attribute removed. At most one such <tt>nest</tt> argument
6528 is allowed, and it must be of pointer type. Calling the new function is
6529 equivalent to calling <tt>func</tt> with the same argument list, but
6530 with <tt>nval</tt> used for the missing <tt>nest</tt> argument. If, after
6531 calling <tt>llvm.init.trampoline</tt>, the memory pointed to
6532 by <tt>tramp</tt> is modified, then the effect of any later call to the
6533 returned function pointer is undefined.</p>
6534
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]6535</div>
6536
6537<!-- ======================================================================= -->
6538<div class="doc_subsection">
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6539 <a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
6540</div>
6541
6542<div class="doc_text">
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6543
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6544<p>These intrinsic functions expand the "universal IR" of LLVM to represent
6545 hardware constructs for atomic operations and memory synchronization. This
6546 provides an interface to the hardware, not an interface to the programmer. It
6547 is aimed at a low enough level to allow any programming models or APIs
6548 (Application Programming Interfaces) which need atomic behaviors to map
6549 cleanly onto it. It is also modeled primarily on hardware behavior. Just as
6550 hardware provides a "universal IR" for source languages, it also provides a
6551 starting point for developing a "universal" atomic operation and
6552 synchronization IR.</p>
6553
6554<p>These do <em>not</em> form an API such as high-level threading libraries,
6555 software transaction memory systems, atomic primitives, and intrinsic
6556 functions as found in BSD, GNU libc, atomic_ops, APR, and other system and
6557 application libraries. The hardware interface provided by LLVM should allow
6558 a clean implementation of all of these APIs and parallel programming models.
6559 No one model or paradigm should be selected above others unless the hardware
6560 itself ubiquitously does so.</p>
6561
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6562</div>
6563
6564<!-- _______________________________________________________________________ -->
6565<div class="doc_subsubsection">
6566 <a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
6567</div>
6568<div class="doc_text">
6569<h5>Syntax:</h5>
6570<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6571 declare void @llvm.memory.barrier( i1 &lt;ll&gt;, i1 &lt;ls&gt;, i1 &lt;sl&gt;, i1 &lt;ss&gt;, i1 &lt;device&gt; )
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6572</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6573
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6574<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6575<p>The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between
6576 specific pairs of memory access types.</p>
6577
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6578<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6579<p>The <tt>llvm.memory.barrier</tt> intrinsic requires five boolean arguments.
6580 The first four arguments enables a specific barrier as listed below. The
6581 fith argument specifies that the barrier applies to io or device or uncached
6582 memory.</p>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6583
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6584<ul>
6585 <li><tt>ll</tt>: load-load barrier</li>
6586 <li><tt>ls</tt>: load-store barrier</li>
6587 <li><tt>sl</tt>: store-load barrier</li>
6588 <li><tt>ss</tt>: store-store barrier</li>
6589 <li><tt>device</tt>: barrier applies to device and uncached memory also.</li>
6590</ul>
6591
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6592<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6593<p>This intrinsic causes the system to enforce some ordering constraints upon
6594 the loads and stores of the program. This barrier does not
6595 indicate <em>when</em> any events will occur, it only enforces
6596 an <em>order</em> in which they occur. For any of the specified pairs of load
6597 and store operations (f.ex. load-load, or store-load), all of the first
6598 operations preceding the barrier will complete before any of the second
6599 operations succeeding the barrier begin. Specifically the semantics for each
6600 pairing is as follows:</p>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6601
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6602<ul>
6603 <li><tt>ll</tt>: All loads before the barrier must complete before any load
6604 after the barrier begins.</li>
6605 <li><tt>ls</tt>: All loads before the barrier must complete before any
6606 store after the barrier begins.</li>
6607 <li><tt>ss</tt>: All stores before the barrier must complete before any
6608 store after the barrier begins.</li>
6609 <li><tt>sl</tt>: All stores before the barrier must complete before any
6610 load after the barrier begins.</li>
6611</ul>
6612
6613<p>These semantics are applied with a logical "and" behavior when more than one
6614 is enabled in a single memory barrier intrinsic.</p>
6615
6616<p>Backends may implement stronger barriers than those requested when they do
6617 not support as fine grained a barrier as requested. Some architectures do
6618 not need all types of barriers and on such architectures, these become
6619 noops.</p>
6620
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6621<h5>Example:</h5>
6622<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6623%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6624%ptr = bitcast i8* %mallocP to i32*
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6625 store i32 4, %ptr
6626
6627%result1 = load i32* %ptr <i>; yields {i32}:result1 = 4</i>
6628 call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
6629 <i>; guarantee the above finishes</i>
6630 store i32 8, %ptr <i>; before this begins</i>
6631</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6632
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]6633</div>
6634
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6635<!-- _______________________________________________________________________ -->
6636<div class="doc_subsubsection">
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6637 <a name="int_atomic_cmp_swap">'<tt>llvm.atomic.cmp.swap.*</tt>' Intrinsic</a>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6638</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6639
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6640<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6641
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6642<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6643<p>This is an overloaded intrinsic. You can use <tt>llvm.atomic.cmp.swap</tt> on
6644 any integer bit width and for different address spaces. Not all targets
6645 support all bit widths however.</p>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6646
6647<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6648 declare i8 @llvm.atomic.cmp.swap.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;cmp&gt;, i8 &lt;val&gt; )
6649 declare i16 @llvm.atomic.cmp.swap.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;cmp&gt;, i16 &lt;val&gt; )
6650 declare i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;cmp&gt;, i32 &lt;val&gt; )
6651 declare i64 @llvm.atomic.cmp.swap.i64.p0i64( i64* &lt;ptr&gt;, i64 &lt;cmp&gt;, i64 &lt;val&gt; )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6652</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6653
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6654<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6655<p>This loads a value in memory and compares it to a given value. If they are
6656 equal, it stores a new value into the memory.</p>
6657
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6658<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6659<p>The <tt>llvm.atomic.cmp.swap</tt> intrinsic takes three arguments. The result
6660 as well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the
6661 same bit width. The <tt>ptr</tt> argument must be a pointer to a value of
6662 this integer type. While any bit width integer may be used, targets may only
6663 lower representations they support in hardware.</p>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6664
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6665<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6666<p>This entire intrinsic must be executed atomically. It first loads the value
6667 in memory pointed to by <tt>ptr</tt> and compares it with the
6668 value <tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the
6669 memory. The loaded value is yielded in all cases. This provides the
6670 equivalent of an atomic compare-and-swap operation within the SSA
6671 framework.</p>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6672
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6673<h5>Examples:</h5>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6674<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6675%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6676%ptr = bitcast i8* %mallocP to i32*
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6677 store i32 4, %ptr
6678
6679%val1 = add i32 4, 4
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6680%result1 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 4, %val1 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6681 <i>; yields {i32}:result1 = 4</i>
6682%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
6683%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
6684
6685%val2 = add i32 1, 1
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6686%result2 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 5, %val2 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6687 <i>; yields {i32}:result2 = 8</i>
6688%stored2 = icmp eq i32 %result2, 5 <i>; yields {i1}:stored2 = false</i>
6689
6690%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 8</i>
6691</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6692
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6693</div>
6694
6695<!-- _______________________________________________________________________ -->
6696<div class="doc_subsubsection">
6697 <a name="int_atomic_swap">'<tt>llvm.atomic.swap.*</tt>' Intrinsic</a>
6698</div>
6699<div class="doc_text">
6700<h5>Syntax:</h5>
6701
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6702<p>This is an overloaded intrinsic. You can use <tt>llvm.atomic.swap</tt> on any
6703 integer bit width. Not all targets support all bit widths however.</p>
6704
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6705<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6706 declare i8 @llvm.atomic.swap.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;val&gt; )
6707 declare i16 @llvm.atomic.swap.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;val&gt; )
6708 declare i32 @llvm.atomic.swap.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;val&gt; )
6709 declare i64 @llvm.atomic.swap.i64.p0i64( i64* &lt;ptr&gt;, i64 &lt;val&gt; )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6710</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6711
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6712<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6713<p>This intrinsic loads the value stored in memory at <tt>ptr</tt> and yields
6714 the value from memory. It then stores the value in <tt>val</tt> in the memory
6715 at <tt>ptr</tt>.</p>
6716
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6717<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6718<p>The <tt>llvm.atomic.swap</tt> intrinsic takes two arguments. Both
6719 the <tt>val</tt> argument and the result must be integers of the same bit
6720 width. The first argument, <tt>ptr</tt>, must be a pointer to a value of this
6721 integer type. The targets may only lower integer representations they
6722 support.</p>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6723
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6724<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6725<p>This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and
6726 stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the
6727 equivalent of an atomic swap operation within the SSA framework.</p>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6728
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6729<h5>Examples:</h5>
6730<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6731%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6732%ptr = bitcast i8* %mallocP to i32*
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6733 store i32 4, %ptr
6734
6735%val1 = add i32 4, 4
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6736%result1 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val1 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6737 <i>; yields {i32}:result1 = 4</i>
6738%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
6739%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
6740
6741%val2 = add i32 1, 1
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6742%result2 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val2 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6743 <i>; yields {i32}:result2 = 8</i>
6744
6745%stored2 = icmp eq i32 %result2, 8 <i>; yields {i1}:stored2 = true</i>
6746%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 2</i>
6747</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6748
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6749</div>
6750
6751<!-- _______________________________________________________________________ -->
6752<div class="doc_subsubsection">
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6753 <a name="int_atomic_load_add">'<tt>llvm.atomic.load.add.*</tt>' Intrinsic</a>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6754
6755</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6756
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6757<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6758
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6759<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6760<p>This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.add</tt> on
6761 any integer bit width. Not all targets support all bit widths however.</p>
6762
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6763<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6764 declare i8 @llvm.atomic.load.add.i8..p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6765 declare i16 @llvm.atomic.load.add.i16..p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6766 declare i32 @llvm.atomic.load.add.i32..p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6767 declare i64 @llvm.atomic.load.add.i64..p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6768</pre>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6769
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6770<h5>Overview:</h5>
6771<p>This intrinsic adds <tt>delta</tt> to the value stored in memory
6772 at <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.</p>
6773
6774<h5>Arguments:</h5>
6775<p>The intrinsic takes two arguments, the first a pointer to an integer value
6776 and the second an integer value. The result is also an integer value. These
6777 integer types can have any bit width, but they must all have the same bit
6778 width. The targets may only lower integer representations they support.</p>
6779
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6780<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6781<p>This intrinsic does a series of operations atomically. It first loads the
6782 value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result
6783 to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.</p>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6784
6785<h5>Examples:</h5>
6786<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6787%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6788%ptr = bitcast i8* %mallocP to i32*
6789 store i32 4, %ptr
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6790%result1 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 4 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6791 <i>; yields {i32}:result1 = 4</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6792%result2 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 2 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6793 <i>; yields {i32}:result2 = 8</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6794%result3 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 5 )
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6795 <i>; yields {i32}:result3 = 10</i>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6796%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 15</i>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6797</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6798
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]6799</div>
6800
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6801<!-- _______________________________________________________________________ -->
6802<div class="doc_subsubsection">
6803 <a name="int_atomic_load_sub">'<tt>llvm.atomic.load.sub.*</tt>' Intrinsic</a>
6804
6805</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6806
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6807<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6808
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6809<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6810<p>This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.sub</tt> on
6811 any integer bit width and for different address spaces. Not all targets
6812 support all bit widths however.</p>
6813
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6814<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6815 declare i8 @llvm.atomic.load.sub.i8.p0i32( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6816 declare i16 @llvm.atomic.load.sub.i16.p0i32( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6817 declare i32 @llvm.atomic.load.sub.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6818 declare i64 @llvm.atomic.load.sub.i64.p0i32( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6819</pre>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6820
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6821<h5>Overview:</h5>
6822<p>This intrinsic subtracts <tt>delta</tt> to the value stored in memory at
6823 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.</p>
6824
6825<h5>Arguments:</h5>
6826<p>The intrinsic takes two arguments, the first a pointer to an integer value
6827 and the second an integer value. The result is also an integer value. These
6828 integer types can have any bit width, but they must all have the same bit
6829 width. The targets may only lower integer representations they support.</p>
6830
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6831<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6832<p>This intrinsic does a series of operations atomically. It first loads the
6833 value stored at <tt>ptr</tt>. It then subtracts <tt>delta</tt>, stores the
6834 result to <tt>ptr</tt>. It yields the original value stored
6835 at <tt>ptr</tt>.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6836
6837<h5>Examples:</h5>
6838<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6839%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6840%ptr = bitcast i8* %mallocP to i32*
6841 store i32 8, %ptr
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6842%result1 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 4 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6843 <i>; yields {i32}:result1 = 8</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6844%result2 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 2 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6845 <i>; yields {i32}:result2 = 4</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6846%result3 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 5 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6847 <i>; yields {i32}:result3 = 2</i>
6848%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = -3</i>
6849</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6850
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6851</div>
6852
6853<!-- _______________________________________________________________________ -->
6854<div class="doc_subsubsection">
6855 <a name="int_atomic_load_and">'<tt>llvm.atomic.load.and.*</tt>' Intrinsic</a><br>
6856 <a name="int_atomic_load_nand">'<tt>llvm.atomic.load.nand.*</tt>' Intrinsic</a><br>
6857 <a name="int_atomic_load_or">'<tt>llvm.atomic.load.or.*</tt>' Intrinsic</a><br>
6858 <a name="int_atomic_load_xor">'<tt>llvm.atomic.load.xor.*</tt>' Intrinsic</a><br>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6859</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6860
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6861<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6862
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6863<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6864<p>These are overloaded intrinsics. You can
6865 use <tt>llvm.atomic.load_and</tt>, <tt>llvm.atomic.load_nand</tt>,
6866 <tt>llvm.atomic.load_or</tt>, and <tt>llvm.atomic.load_xor</tt> on any integer
6867 bit width and for different address spaces. Not all targets support all bit
6868 widths however.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6869
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6870<pre>
6871 declare i8 @llvm.atomic.load.and.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6872 declare i16 @llvm.atomic.load.and.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6873 declare i32 @llvm.atomic.load.and.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6874 declare i64 @llvm.atomic.load.and.i64.p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6875</pre>
6876
6877<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6878 declare i8 @llvm.atomic.load.or.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6879 declare i16 @llvm.atomic.load.or.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6880 declare i32 @llvm.atomic.load.or.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6881 declare i64 @llvm.atomic.load.or.i64.p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6882</pre>
6883
6884<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6885 declare i8 @llvm.atomic.load.nand.i8.p0i32( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6886 declare i16 @llvm.atomic.load.nand.i16.p0i32( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6887 declare i32 @llvm.atomic.load.nand.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6888 declare i64 @llvm.atomic.load.nand.i64.p0i32( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6889</pre>
6890
6891<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6892 declare i8 @llvm.atomic.load.xor.i8.p0i32( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6893 declare i16 @llvm.atomic.load.xor.i16.p0i32( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6894 declare i32 @llvm.atomic.load.xor.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6895 declare i64 @llvm.atomic.load.xor.i64.p0i32( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6896</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6897
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6898<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6899<p>These intrinsics bitwise the operation (and, nand, or, xor) <tt>delta</tt> to
6900 the value stored in memory at <tt>ptr</tt>. It yields the original value
6901 at <tt>ptr</tt>.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6902
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6903<h5>Arguments:</h5>
6904<p>These intrinsics take two arguments, the first a pointer to an integer value
6905 and the second an integer value. The result is also an integer value. These
6906 integer types can have any bit width, but they must all have the same bit
6907 width. The targets may only lower integer representations they support.</p>
6908
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6909<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6910<p>These intrinsics does a series of operations atomically. They first load the
6911 value stored at <tt>ptr</tt>. They then do the bitwise
6912 operation <tt>delta</tt>, store the result to <tt>ptr</tt>. They yield the
6913 original value stored at <tt>ptr</tt>.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6914
6915<h5>Examples:</h5>
6916<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6917%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6918%ptr = bitcast i8* %mallocP to i32*
6919 store i32 0x0F0F, %ptr
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6920%result0 = call i32 @llvm.atomic.load.nand.i32.p0i32( i32* %ptr, i32 0xFF )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6921 <i>; yields {i32}:result0 = 0x0F0F</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6922%result1 = call i32 @llvm.atomic.load.and.i32.p0i32( i32* %ptr, i32 0xFF )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6923 <i>; yields {i32}:result1 = 0xFFFFFFF0</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6924%result2 = call i32 @llvm.atomic.load.or.i32.p0i32( i32* %ptr, i32 0F )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6925 <i>; yields {i32}:result2 = 0xF0</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6926%result3 = call i32 @llvm.atomic.load.xor.i32.p0i32( i32* %ptr, i32 0F )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6927 <i>; yields {i32}:result3 = FF</i>
6928%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = F0</i>
6929</pre>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6930
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6931</div>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6932
6933<!-- _______________________________________________________________________ -->
6934<div class="doc_subsubsection">
6935 <a name="int_atomic_load_max">'<tt>llvm.atomic.load.max.*</tt>' Intrinsic</a><br>
6936 <a name="int_atomic_load_min">'<tt>llvm.atomic.load.min.*</tt>' Intrinsic</a><br>
6937 <a name="int_atomic_load_umax">'<tt>llvm.atomic.load.umax.*</tt>' Intrinsic</a><br>
6938 <a name="int_atomic_load_umin">'<tt>llvm.atomic.load.umin.*</tt>' Intrinsic</a><br>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6939</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6940
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6941<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6942
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6943<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6944<p>These are overloaded intrinsics. You can use <tt>llvm.atomic.load_max</tt>,
6945 <tt>llvm.atomic.load_min</tt>, <tt>llvm.atomic.load_umax</tt>, and
6946 <tt>llvm.atomic.load_umin</tt> on any integer bit width and for different
6947 address spaces. Not all targets support all bit widths however.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6948
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6949<pre>
6950 declare i8 @llvm.atomic.load.max.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6951 declare i16 @llvm.atomic.load.max.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6952 declare i32 @llvm.atomic.load.max.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6953 declare i64 @llvm.atomic.load.max.i64.p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6954</pre>
6955
6956<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6957 declare i8 @llvm.atomic.load.min.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6958 declare i16 @llvm.atomic.load.min.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6959 declare i32 @llvm.atomic.load.min.i32..p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6960 declare i64 @llvm.atomic.load.min.i64..p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6961</pre>
6962
6963<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6964 declare i8 @llvm.atomic.load.umax.i8.p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6965 declare i16 @llvm.atomic.load.umax.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6966 declare i32 @llvm.atomic.load.umax.i32.p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6967 declare i64 @llvm.atomic.load.umax.i64.p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6968</pre>
6969
6970<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6971 declare i8 @llvm.atomic.load.umin.i8..p0i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
6972 declare i16 @llvm.atomic.load.umin.i16.p0i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
6973 declare i32 @llvm.atomic.load.umin.i32..p0i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
6974 declare i64 @llvm.atomic.load.umin.i64..p0i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6975</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6976
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6977<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6978<p>These intrinsics takes the signed or unsigned minimum or maximum of
6979 <tt>delta</tt> and the value stored in memory at <tt>ptr</tt>. It yields the
6980 original value at <tt>ptr</tt>.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6981
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6982<h5>Arguments:</h5>
6983<p>These intrinsics take two arguments, the first a pointer to an integer value
6984 and the second an integer value. The result is also an integer value. These
6985 integer types can have any bit width, but they must all have the same bit
6986 width. The targets may only lower integer representations they support.</p>
6987
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6988<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]6989<p>These intrinsics does a series of operations atomically. They first load the
6990 value stored at <tt>ptr</tt>. They then do the signed or unsigned min or
6991 max <tt>delta</tt> and the value, store the result to <tt>ptr</tt>. They
6992 yield the original value stored at <tt>ptr</tt>.</p>
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]6993
6994<h5>Examples:</h5>
6995<pre>
Victor Hernandez6b054092009-10-26 23:44:29 +0000[diff] [blame]6996%mallocP = tail call i8* @malloc(i32 ptrtoint (i32* getelementptr (i32* null, i32 1) to i32))
6997%ptr = bitcast i8* %mallocP to i32*
6998 store i32 7, %ptr
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]6999%result0 = call i32 @llvm.atomic.load.min.i32.p0i32( i32* %ptr, i32 -2 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]7000 <i>; yields {i32}:result0 = 7</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]7001%result1 = call i32 @llvm.atomic.load.max.i32.p0i32( i32* %ptr, i32 8 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]7002 <i>; yields {i32}:result1 = -2</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]7003%result2 = call i32 @llvm.atomic.load.umin.i32.p0i32( i32* %ptr, i32 10 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]7004 <i>; yields {i32}:result2 = 8</i>
Mon P Wangce3ac892008-07-30 04:36:53 +0000[diff] [blame]7005%result3 = call i32 @llvm.atomic.load.umax.i32.p0i32( i32* %ptr, i32 30 )
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]7006 <i>; yields {i32}:result3 = 8</i>
7007%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 30</i>
7008</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7009
Mon P Wang6bde9ec2008-06-25 08:15:39 +0000[diff] [blame]7010</div>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]7011
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]7012
7013<!-- ======================================================================= -->
7014<div class="doc_subsection">
7015 <a name="int_memorymarkers">Memory Use Markers</a>
7016</div>
7017
7018<div class="doc_text">
7019
7020<p>This class of intrinsics exists to information about the lifetime of memory
7021 objects and ranges where variables are immutable.</p>
7022
7023</div>
7024
7025<!-- _______________________________________________________________________ -->
7026<div class="doc_subsubsection">
7027 <a name="int_lifetime_start">'<tt>llvm.lifetime.start</tt>' Intrinsic</a>
7028</div>
7029
7030<div class="doc_text">
7031
7032<h5>Syntax:</h5>
7033<pre>
7034 declare void @llvm.lifetime.start(i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;)
7035</pre>
7036
7037<h5>Overview:</h5>
7038<p>The '<tt>llvm.lifetime.start</tt>' intrinsic specifies the start of a memory
7039 object's lifetime.</p>
7040
7041<h5>Arguments:</h5>
Nick Lewycky23f49982009-10-13 07:57:33 +0000[diff] [blame]7042<p>The first argument is a constant integer representing the size of the
7043 object, or -1 if it is variable sized. The second argument is a pointer to
7044 the object.</p>
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]7045
7046<h5>Semantics:</h5>
7047<p>This intrinsic indicates that before this point in the code, the value of the
7048 memory pointed to by <tt>ptr</tt> is dead. This means that it is known to
Nick Lewyckyf8a5f302009-10-27 16:56:58 +0000[diff] [blame]7049 never be used and has an undefined value. A load from the pointer that
7050 precedes this intrinsic can be replaced with
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]7051 <tt>'<a href="#undefvalues">undef</a>'</tt>.</p>
7052
7053</div>
7054
7055<!-- _______________________________________________________________________ -->
7056<div class="doc_subsubsection">
7057 <a name="int_lifetime_end">'<tt>llvm.lifetime.end</tt>' Intrinsic</a>
7058</div>
7059
7060<div class="doc_text">
7061
7062<h5>Syntax:</h5>
7063<pre>
7064 declare void @llvm.lifetime.end(i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;)
7065</pre>
7066
7067<h5>Overview:</h5>
7068<p>The '<tt>llvm.lifetime.end</tt>' intrinsic specifies the end of a memory
7069 object's lifetime.</p>
7070
7071<h5>Arguments:</h5>
Nick Lewycky23f49982009-10-13 07:57:33 +0000[diff] [blame]7072<p>The first argument is a constant integer representing the size of the
7073 object, or -1 if it is variable sized. The second argument is a pointer to
7074 the object.</p>
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]7075
7076<h5>Semantics:</h5>
7077<p>This intrinsic indicates that after this point in the code, the value of the
7078 memory pointed to by <tt>ptr</tt> is dead. This means that it is known to
7079 never be used and has an undefined value. Any stores into the memory object
7080 following this intrinsic may be removed as dead.
7081
7082</div>
7083
7084<!-- _______________________________________________________________________ -->
7085<div class="doc_subsubsection">
7086 <a name="int_invariant_start">'<tt>llvm.invariant.start</tt>' Intrinsic</a>
7087</div>
7088
7089<div class="doc_text">
7090
7091<h5>Syntax:</h5>
7092<pre>
7093 declare {}* @llvm.invariant.start(i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;) readonly
7094</pre>
7095
7096<h5>Overview:</h5>
7097<p>The '<tt>llvm.invariant.start</tt>' intrinsic specifies that the contents of
7098 a memory object will not change.</p>
7099
7100<h5>Arguments:</h5>
Nick Lewycky23f49982009-10-13 07:57:33 +0000[diff] [blame]7101<p>The first argument is a constant integer representing the size of the
7102 object, or -1 if it is variable sized. The second argument is a pointer to
7103 the object.</p>
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]7104
7105<h5>Semantics:</h5>
7106<p>This intrinsic indicates that until an <tt>llvm.invariant.end</tt> that uses
7107 the return value, the referenced memory location is constant and
7108 unchanging.</p>
7109
7110</div>
7111
7112<!-- _______________________________________________________________________ -->
7113<div class="doc_subsubsection">
7114 <a name="int_invariant_end">'<tt>llvm.invariant.end</tt>' Intrinsic</a>
7115</div>
7116
7117<div class="doc_text">
7118
7119<h5>Syntax:</h5>
7120<pre>
7121 declare void @llvm.invariant.end({}* &lt;start&gt;, i64 &lt;size&gt;, i8* nocapture &lt;ptr&gt;)
7122</pre>
7123
7124<h5>Overview:</h5>
7125<p>The '<tt>llvm.invariant.end</tt>' intrinsic specifies that the contents of
7126 a memory object are mutable.</p>
7127
7128<h5>Arguments:</h5>
7129<p>The first argument is the matching <tt>llvm.invariant.start</tt> intrinsic.
Nick Lewycky23f49982009-10-13 07:57:33 +0000[diff] [blame]7130 The second argument is a constant integer representing the size of the
7131 object, or -1 if it is variable sized and the third argument is a pointer
7132 to the object.</p>
Nick Lewyckyc888d352009-10-13 07:03:23 +0000[diff] [blame]7133
7134<h5>Semantics:</h5>
7135<p>This intrinsic indicates that the memory is mutable again.</p>
7136
7137</div>
7138
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]7139<!-- ======================================================================= -->
7140<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7141 <a name="int_general">General Intrinsics</a>
7142</div>
7143
7144<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7145
7146<p>This class of intrinsics is designed to be generic and has no specific
7147 purpose.</p>
7148
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7149</div>
7150
7151<!-- _______________________________________________________________________ -->
7152<div class="doc_subsubsection">
7153 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
7154</div>
7155
7156<div class="doc_text">
7157
7158<h5>Syntax:</h5>
7159<pre>
7160 declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
7161</pre>
7162
7163<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7164<p>The '<tt>llvm.var.annotation</tt>' intrinsic.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7165
7166<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7167<p>The first argument is a pointer to a value, the second is a pointer to a
7168 global string, the third is a pointer to a global string which is the source
7169 file name, and the last argument is the line number.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7170
7171<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7172<p>This intrinsic allows annotation of local variables with arbitrary strings.
7173 This can be useful for special purpose optimizations that want to look for
7174 these annotations. These have no other defined use, they are ignored by code
7175 generation and optimization.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7176
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7177</div>
7178
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7179<!-- _______________________________________________________________________ -->
7180<div class="doc_subsubsection">
Tanya Lattnerc9869b12007-09-21 23:57:59 +0000[diff] [blame]7181 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7182</div>
7183
7184<div class="doc_text">
7185
7186<h5>Syntax:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7187<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
7188 any integer bit width.</p>
7189
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7190<pre>
Tanya Lattner09161fe2007-09-22 00:03:01 +0000[diff] [blame]7191 declare i8 @llvm.annotation.i8(i8 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
7192 declare i16 @llvm.annotation.i16(i16 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
7193 declare i32 @llvm.annotation.i32(i32 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
7194 declare i64 @llvm.annotation.i64(i64 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
7195 declare i256 @llvm.annotation.i256(i256 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7196</pre>
7197
7198<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7199<p>The '<tt>llvm.annotation</tt>' intrinsic.</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7200
7201<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7202<p>The first argument is an integer value (result of some expression), the
7203 second is a pointer to a global string, the third is a pointer to a global
7204 string which is the source file name, and the last argument is the line
7205 number. It returns the value of the first argument.</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7206
7207<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7208<p>This intrinsic allows annotations to be put on arbitrary expressions with
7209 arbitrary strings. This can be useful for special purpose optimizations that
7210 want to look for these annotations. These have no other defined use, they
7211 are ignored by code generation and optimization.</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7212
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]7213</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7214
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]7215<!-- _______________________________________________________________________ -->
7216<div class="doc_subsubsection">
7217 <a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
7218</div>
7219
7220<div class="doc_text">
7221
7222<h5>Syntax:</h5>
7223<pre>
7224 declare void @llvm.trap()
7225</pre>
7226
7227<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7228<p>The '<tt>llvm.trap</tt>' intrinsic.</p>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]7229
7230<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7231<p>None.</p>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]7232
7233<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7234<p>This intrinsics is lowered to the target dependent trap instruction. If the
7235 target does not have a trap instruction, this intrinsic will be lowered to
7236 the call of the <tt>abort()</tt> function.</p>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]7237
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]7238</div>
7239
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7240<!-- _______________________________________________________________________ -->
7241<div class="doc_subsubsection">
Misha Brukman5dd7f4d2008-11-22 23:55:29 +0000[diff] [blame]7242 <a name="int_stackprotector">'<tt>llvm.stackprotector</tt>' Intrinsic</a>
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7243</div>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7244
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7245<div class="doc_text">
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7246
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7247<h5>Syntax:</h5>
7248<pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7249 declare void @llvm.stackprotector( i8* &lt;guard&gt;, i8** &lt;slot&gt; )
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7250</pre>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7251
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7252<h5>Overview:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7253<p>The <tt>llvm.stackprotector</tt> intrinsic takes the <tt>guard</tt> and
7254 stores it onto the stack at <tt>slot</tt>. The stack slot is adjusted to
7255 ensure that it is placed on the stack before local variables.</p>
7256
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7257<h5>Arguments:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7258<p>The <tt>llvm.stackprotector</tt> intrinsic requires two pointer
7259 arguments. The first argument is the value loaded from the stack
7260 guard <tt>@__stack_chk_guard</tt>. The second variable is an <tt>alloca</tt>
7261 that has enough space to hold the value of the guard.</p>
7262
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7263<h5>Semantics:</h5>
Bill Wendlingf85859d2009-07-20 02:29:24 +0000[diff] [blame]7264<p>This intrinsic causes the prologue/epilogue inserter to force the position of
7265 the <tt>AllocaInst</tt> stack slot to be before local variables on the
7266 stack. This is to ensure that if a local variable on the stack is
7267 overwritten, it will destroy the value of the guard. When the function exits,
7268 the guard on the stack is checked against the original guard. If they're
7269 different, then the program aborts by calling the <tt>__stack_chk_fail()</tt>
7270 function.</p>
7271
Bill Wendlinge4164592008-11-19 05:56:17 +0000[diff] [blame]7272</div>
7273
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7274<!-- *********************************************************************** -->
7275<hr>
7276<address>
7277 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]7278 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7279 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]7280 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7281
7282 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
7283 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
7284 Last modified: $Date$
7285</address>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]7286
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]7287</body>
7288</html>