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gerrit-public.fairphone.software / toolchain / llvm-project / b18f8f85e9151195a81833d6862063323338854e / . / llvm / docs / LangRef.html
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4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]25 <li><a href="#globalvars">Global Variables</a></li>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]26 <li><a href="#functionstructure">Functions</a></li>
Anton Korobeynikovb18f8f82007-04-28 13:45:00 +0000[diff] [blame^]27 <li><a href="aliasstructure">Aliases</a>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]28 <li><a href="#paramattrs">Parameter Attributes</a></li>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]29 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]30 <li><a href="#datalayout">Data Layout</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]31 </ol>
32 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]33 <li><a href="#typesystem">Type System</a>
34 <ol>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]35 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]36 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]37 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]38 </ol>
39 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]40 <li><a href="#t_derived">Derived Types</a>
41 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]42 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]43 <li><a href="#t_function">Function Type</a></li>
44 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]45 <li><a href="#t_struct">Structure Type</a></li>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]46 <li><a href="#t_pstruct">Packed Structure Type</a></li>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]47 <li><a href="#t_vector">Vector Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]48 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]49 </ol>
50 </li>
51 </ol>
52 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]53 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]54 <ol>
55 <li><a href="#simpleconstants">Simple Constants</a>
56 <li><a href="#aggregateconstants">Aggregate Constants</a>
57 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
58 <li><a href="#undefvalues">Undefined Values</a>
59 <li><a href="#constantexprs">Constant Expressions</a>
60 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]61 </li>
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]62 <li><a href="#othervalues">Other Values</a>
63 <ol>
64 <li><a href="#inlineasm">Inline Assembler Expressions</a>
65 </ol>
66 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]67 <li><a href="#instref">Instruction Reference</a>
68 <ol>
69 <li><a href="#terminators">Terminator Instructions</a>
70 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]71 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
72 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]73 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
74 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]75 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]76 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]77 </ol>
78 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]79 <li><a href="#binaryops">Binary Operations</a>
80 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]81 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
82 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
83 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]84 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
85 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
86 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]87 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
88 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
89 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]90 </ol>
91 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]92 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
93 <ol>
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]94 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
95 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
96 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]97 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]98 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]99 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]100 </ol>
101 </li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]102 <li><a href="#vectorops">Vector Operations</a>
103 <ol>
104 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
105 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
106 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]107 </ol>
108 </li>
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]109 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]110 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]111 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
112 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
113 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]114 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
115 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
116 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]117 </ol>
118 </li>
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]119 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]120 <ol>
121 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
122 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
123 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
124 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
125 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]126 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
127 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
128 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
129 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]130 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
131 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]132 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]133 </ol>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]134 <li><a href="#otherops">Other Operations</a>
135 <ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]136 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
137 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]138 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]139 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]140 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]141 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]142 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]143 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]144 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]145 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]146 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]147 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]148 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
149 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]150 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
151 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
152 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]153 </ol>
154 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]155 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
156 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]157 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
158 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
159 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]160 </ol>
161 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]162 <li><a href="#int_codegen">Code Generator Intrinsics</a>
163 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]164 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
165 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
166 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
167 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
168 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
169 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
170 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]171 </ol>
172 </li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]173 <li><a href="#int_libc">Standard C Library Intrinsics</a>
174 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]175 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
176 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
177 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
178 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
179 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]180 </ol>
181 </li>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]182 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]183 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]184 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]185 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
186 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
187 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Reid Spencer5bf54c82007-04-11 23:23:49 +0000[diff] [blame]188 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
189 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]190 </ol>
191 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]192 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Jim Laskey2211f492007-03-14 19:31:19 +0000[diff] [blame]193 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]194 </ol>
195 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]196</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]197
198<div class="doc_author">
199 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
200 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]201</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]202
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]203<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]204<div class="doc_section"> <a name="abstract">Abstract </a></div>
205<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]206
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]207<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]208<p>This document is a reference manual for the LLVM assembly language.
209LLVM is an SSA based representation that provides type safety,
210low-level operations, flexibility, and the capability of representing
211'all' high-level languages cleanly. It is the common code
212representation used throughout all phases of the LLVM compilation
213strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]214</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]215
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]216<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]217<div class="doc_section"> <a name="introduction">Introduction</a> </div>
218<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]219
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]220<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]221
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]222<p>The LLVM code representation is designed to be used in three
223different forms: as an in-memory compiler IR, as an on-disk bytecode
224representation (suitable for fast loading by a Just-In-Time compiler),
225and as a human readable assembly language representation. This allows
226LLVM to provide a powerful intermediate representation for efficient
227compiler transformations and analysis, while providing a natural means
228to debug and visualize the transformations. The three different forms
229of LLVM are all equivalent. This document describes the human readable
230representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]231
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]232<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]233while being expressive, typed, and extensible at the same time. It
234aims to be a "universal IR" of sorts, by being at a low enough level
235that high-level ideas may be cleanly mapped to it (similar to how
236microprocessors are "universal IR's", allowing many source languages to
237be mapped to them). By providing type information, LLVM can be used as
238the target of optimizations: for example, through pointer analysis, it
239can be proven that a C automatic variable is never accessed outside of
240the current function... allowing it to be promoted to a simple SSA
241value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]242
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]243</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]244
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]245<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]246<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]247
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]248<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]249
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]250<p>It is important to note that this document describes 'well formed'
251LLVM assembly language. There is a difference between what the parser
252accepts and what is considered 'well formed'. For example, the
253following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]254
255<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]256 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]257</pre>
258
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]259<p>...because the definition of <tt>%x</tt> does not dominate all of
260its uses. The LLVM infrastructure provides a verification pass that may
261be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]262automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]263the optimizer before it outputs bytecode. The violations pointed out
264by the verifier pass indicate bugs in transformation passes or input to
265the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]266
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]267<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]268
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]269<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]270<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]271<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]272
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]273<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]274
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]275<p>LLVM uses three different forms of identifiers, for different
276purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]277
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]278<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]279 <li>Named values are represented as a string of characters with a '%' prefix.
280 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
281 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
282 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]283 with quotes. In this way, anything except a <tt>&quot;</tt> character can be used
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]284 in a name.</li>
285
286 <li>Unnamed values are represented as an unsigned numeric value with a '%'
287 prefix. For example, %12, %2, %44.</li>
288
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]289 <li>Constants, which are described in a <a href="#constants">section about
290 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]291</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]292
293<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
294don't need to worry about name clashes with reserved words, and the set of
295reserved words may be expanded in the future without penalty. Additionally,
296unnamed identifiers allow a compiler to quickly come up with a temporary
297variable without having to avoid symbol table conflicts.</p>
298
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]299<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]300languages. There are keywords for different opcodes
301('<tt><a href="#i_add">add</a></tt>',
302 '<tt><a href="#i_bitcast">bitcast</a></tt>',
303 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]304href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]305and others. These reserved words cannot conflict with variable names, because
306none of them start with a '%' character.</p>
307
308<p>Here is an example of LLVM code to multiply the integer variable
309'<tt>%X</tt>' by 8:</p>
310
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]311<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]312
313<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]314 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]315</pre>
316
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]317<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]318
319<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]320 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]321</pre>
322
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]323<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]324
325<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]326 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
327 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
328 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]329</pre>
330
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]331<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
332important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]333
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]334<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]335
336 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
337 line.</li>
338
339 <li>Unnamed temporaries are created when the result of a computation is not
340 assigned to a named value.</li>
341
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]342 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]343
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]344</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]345
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]346<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]347demonstrating instructions, we will follow an instruction with a comment that
348defines the type and name of value produced. Comments are shown in italic
349text.</p>
350
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]351</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]352
353<!-- *********************************************************************** -->
354<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
355<!-- *********************************************************************** -->
356
357<!-- ======================================================================= -->
358<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
359</div>
360
361<div class="doc_text">
362
363<p>LLVM programs are composed of "Module"s, each of which is a
364translation unit of the input programs. Each module consists of
365functions, global variables, and symbol table entries. Modules may be
366combined together with the LLVM linker, which merges function (and
367global variable) definitions, resolves forward declarations, and merges
368symbol table entries. Here is an example of the "hello world" module:</p>
369
370<pre><i>; Declare the string constant as a global constant...</i>
371<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]372 href="#globalvars">constant</a> <a href="#t_array">[13 x i8 ]</a> c"hello world\0A\00" <i>; [13 x i8 ]*</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]373
374<i>; External declaration of the puts function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]375<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]376
377<i>; Definition of main function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]378define i32 %main() { <i>; i32()* </i>
379 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]380 %cast210 = <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]381 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* %.LC0, i64 0, i64 0 <i>; i8 *</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]382
383 <i>; Call puts function to write out the string to stdout...</i>
384 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]385 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]386 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]387 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]388
389<p>This example is made up of a <a href="#globalvars">global variable</a>
390named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
391function, and a <a href="#functionstructure">function definition</a>
392for "<tt>main</tt>".</p>
393
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]394<p>In general, a module is made up of a list of global values,
395where both functions and global variables are global values. Global values are
396represented by a pointer to a memory location (in this case, a pointer to an
397array of char, and a pointer to a function), and have one of the following <a
398href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]399
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]400</div>
401
402<!-- ======================================================================= -->
403<div class="doc_subsection">
404 <a name="linkage">Linkage Types</a>
405</div>
406
407<div class="doc_text">
408
409<p>
410All Global Variables and Functions have one of the following types of linkage:
411</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]412
413<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]414
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]415 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]416
417 <dd>Global values with internal linkage are only directly accessible by
418 objects in the current module. In particular, linking code into a module with
419 an internal global value may cause the internal to be renamed as necessary to
420 avoid collisions. Because the symbol is internal to the module, all
421 references can be updated. This corresponds to the notion of the
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]422 '<tt>static</tt>' keyword in C.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]423 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]424
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]425 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]426
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]427 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
428 the same name when linkage occurs. This is typically used to implement
429 inline functions, templates, or other code which must be generated in each
430 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
431 allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]432 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]433
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]434 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]435
436 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
437 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]438 used for globals that may be emitted in multiple translation units, but that
439 are not guaranteed to be emitted into every translation unit that uses them.
440 One example of this are common globals in C, such as "<tt>int X;</tt>" at
441 global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]442 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]443
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]444 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]445
446 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
447 pointer to array type. When two global variables with appending linkage are
448 linked together, the two global arrays are appended together. This is the
449 LLVM, typesafe, equivalent of having the system linker append together
450 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]451 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]452
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]453 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
454 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
455 until linked, if not linked, the symbol becomes null instead of being an
456 undefined reference.
457 </dd>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]458
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]459 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]460
461 <dd>If none of the above identifiers are used, the global is externally
462 visible, meaning that it participates in linkage and can be used to resolve
463 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]464 </dd>
Reid Spencer7972c472007-04-11 23:49:50 +0000[diff] [blame]465</dl>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]466
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]467 <p>
468 The next two types of linkage are targeted for Microsoft Windows platform
469 only. They are designed to support importing (exporting) symbols from (to)
470 DLLs.
471 </p>
472
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]473 <dl>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]474 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
475
476 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
477 or variable via a global pointer to a pointer that is set up by the DLL
478 exporting the symbol. On Microsoft Windows targets, the pointer name is
479 formed by combining <code>_imp__</code> and the function or variable name.
480 </dd>
481
482 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
483
484 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
485 pointer to a pointer in a DLL, so that it can be referenced with the
486 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
487 name is formed by combining <code>_imp__</code> and the function or variable
488 name.
489 </dd>
490
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]491</dl>
492
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]493<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]494variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
495variable and was linked with this one, one of the two would be renamed,
496preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
497external (i.e., lacking any linkage declarations), they are accessible
Reid Spencer92c671e2007-01-05 00:59:10 +0000[diff] [blame]498outside of the current module.</p>
499<p>It is illegal for a function <i>declaration</i>
500to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]501or <tt>extern_weak</tt>.</p>
Anton Korobeynikova97b6942007-04-25 14:27:10 +0000[diff] [blame]502<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
503linkages.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]504</div>
505
506<!-- ======================================================================= -->
507<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]508 <a name="callingconv">Calling Conventions</a>
509</div>
510
511<div class="doc_text">
512
513<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
514and <a href="#i_invoke">invokes</a> can all have an optional calling convention
515specified for the call. The calling convention of any pair of dynamic
516caller/callee must match, or the behavior of the program is undefined. The
517following calling conventions are supported by LLVM, and more may be added in
518the future:</p>
519
520<dl>
521 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
522
523 <dd>This calling convention (the default if no other calling convention is
524 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]525 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencer72ba4992006-12-31 21:30:18 +0000[diff] [blame]526 prototype and implemented declaration of the function (as does normal C).
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]527 </dd>
528
529 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
530
531 <dd>This calling convention attempts to make calls as fast as possible
532 (e.g. by passing things in registers). This calling convention allows the
533 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]534 without having to conform to an externally specified ABI. Implementations of
535 this convention should allow arbitrary tail call optimization to be supported.
536 This calling convention does not support varargs and requires the prototype of
537 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]538 </dd>
539
540 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
541
542 <dd>This calling convention attempts to make code in the caller as efficient
543 as possible under the assumption that the call is not commonly executed. As
544 such, these calls often preserve all registers so that the call does not break
545 any live ranges in the caller side. This calling convention does not support
546 varargs and requires the prototype of all callees to exactly match the
547 prototype of the function definition.
548 </dd>
549
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]550 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]551
552 <dd>Any calling convention may be specified by number, allowing
553 target-specific calling conventions to be used. Target specific calling
554 conventions start at 64.
555 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]556</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]557
558<p>More calling conventions can be added/defined on an as-needed basis, to
559support pascal conventions or any other well-known target-independent
560convention.</p>
561
562</div>
563
564<!-- ======================================================================= -->
565<div class="doc_subsection">
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]566 <a name="visibility">Visibility Styles</a>
567</div>
568
569<div class="doc_text">
570
571<p>
572All Global Variables and Functions have one of the following visibility styles:
573</p>
574
575<dl>
576 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
577
578 <dd>On ELF, default visibility means that the declaration is visible to other
579 modules and, in shared libraries, means that the declared entity may be
580 overridden. On Darwin, default visibility means that the declaration is
581 visible to other modules. Default visibility corresponds to "external
582 linkage" in the language.
583 </dd>
584
585 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
586
587 <dd>Two declarations of an object with hidden visibility refer to the same
588 object if they are in the same shared object. Usually, hidden visibility
589 indicates that the symbol will not be placed into the dynamic symbol table,
590 so no other module (executable or shared library) can reference it
591 directly.
592 </dd>
593
594</dl>
595
596</div>
597
598<!-- ======================================================================= -->
599<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]600 <a name="globalvars">Global Variables</a>
601</div>
602
603<div class="doc_text">
604
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]605<p>Global variables define regions of memory allocated at compilation time
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]606instead of run-time. Global variables may optionally be initialized, may have
Anton Korobeynikova97b6942007-04-25 14:27:10 +0000[diff] [blame]607an explicit section to be placed in, and may have an optional explicit alignment
608specified. A variable may be defined as "thread_local", which means that it
609will not be shared by threads (each thread will have a separated copy of the
610variable). A variable may be defined as a global "constant," which indicates
611that the contents of the variable will <b>never</b> be modified (enabling better
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]612optimization, allowing the global data to be placed in the read-only section of
613an executable, etc). Note that variables that need runtime initialization
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]614cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]615
616<p>
617LLVM explicitly allows <em>declarations</em> of global variables to be marked
618constant, even if the final definition of the global is not. This capability
619can be used to enable slightly better optimization of the program, but requires
620the language definition to guarantee that optimizations based on the
621'constantness' are valid for the translation units that do not include the
622definition.
623</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]624
625<p>As SSA values, global variables define pointer values that are in
626scope (i.e. they dominate) all basic blocks in the program. Global
627variables always define a pointer to their "content" type because they
628describe a region of memory, and all memory objects in LLVM are
629accessed through pointers.</p>
630
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]631<p>LLVM allows an explicit section to be specified for globals. If the target
632supports it, it will emit globals to the section specified.</p>
633
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]634<p>An explicit alignment may be specified for a global. If not present, or if
635the alignment is set to zero, the alignment of the global is set by the target
636to whatever it feels convenient. If an explicit alignment is specified, the
637global is forced to have at least that much alignment. All alignments must be
638a power of 2.</p>
639
Chris Lattner5760c502007-01-14 00:27:09 +0000[diff] [blame]640<p>For example, the following defines a global with an initializer, section,
641 and alignment:</p>
642
643<pre>
644 %G = constant float 1.0, section "foo", align 4
645</pre>
646
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]647</div>
648
649
650<!-- ======================================================================= -->
651<div class="doc_subsection">
652 <a name="functionstructure">Functions</a>
653</div>
654
655<div class="doc_text">
656
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]657<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
658an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]659<a href="#visibility">visibility style</a>, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]660<a href="#callingconv">calling convention</a>, a return type, an optional
661<a href="#paramattrs">parameter attribute</a> for the return type, a function
662name, a (possibly empty) argument list (each with optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]663<a href="#paramattrs">parameter attributes</a>), an optional section, an
664optional alignment, an opening curly brace, a list of basic blocks, and a
665closing curly brace.
666
667LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
668optional <a href="#linkage">linkage type</a>, an optional
669<a href="#visibility">visibility style</a>, an optional
670<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]671<a href="#paramattrs">parameter attribute</a> for the return type, a function
672name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]673
674<p>A function definition contains a list of basic blocks, forming the CFG for
675the function. Each basic block may optionally start with a label (giving the
676basic block a symbol table entry), contains a list of instructions, and ends
677with a <a href="#terminators">terminator</a> instruction (such as a branch or
678function return).</p>
679
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]680<p>The first basic block in a program is special in two ways: it is immediately
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]681executed on entrance to the function, and it is not allowed to have predecessor
682basic blocks (i.e. there can not be any branches to the entry block of a
683function). Because the block can have no predecessors, it also cannot have any
684<a href="#i_phi">PHI nodes</a>.</p>
685
686<p>LLVM functions are identified by their name and type signature. Hence, two
687functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]688considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]689appropriately.</p>
690
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]691<p>LLVM allows an explicit section to be specified for functions. If the target
692supports it, it will emit functions to the section specified.</p>
693
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]694<p>An explicit alignment may be specified for a function. If not present, or if
695the alignment is set to zero, the alignment of the function is set by the target
696to whatever it feels convenient. If an explicit alignment is specified, the
697function is forced to have at least that much alignment. All alignments must be
698a power of 2.</p>
699
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]700</div>
701
Anton Korobeynikova97b6942007-04-25 14:27:10 +0000[diff] [blame]702
703<!-- ======================================================================= -->
704<div class="doc_subsection">
705 <a name="aliasstructure">Aliases</a>
706</div>
707<div class="doc_text">
708 <p>Aliases act as "second name" for the aliasee value (which can be either
Anton Korobeynikovb18f8f82007-04-28 13:45:00 +0000[diff] [blame^]709 function or global variable or bitcast of global value). Aliases may have an
Anton Korobeynikova97b6942007-04-25 14:27:10 +0000[diff] [blame]710 optional <a href="#linkage">linkage type</a>, and an
711 optional <a href="#visibility">visibility style</a>.</p>
712
713 <h5>Syntax:</h5>
714
715 <pre>
716 @&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
717 </pre>
718
719</div>
720
721
722
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]723<!-- ======================================================================= -->
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]724<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
725<div class="doc_text">
726 <p>The return type and each parameter of a function type may have a set of
727 <i>parameter attributes</i> associated with them. Parameter attributes are
728 used to communicate additional information about the result or parameters of
729 a function. Parameter attributes are considered to be part of the function
730 type so two functions types that differ only by the parameter attributes
731 are different function types.</p>
732
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]733 <p>Parameter attributes are simple keywords that follow the type specified. If
734 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]735 example:</p><pre>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]736 %someFunc = i16 (i8 sext %someParam) zext
737 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]738 <p>Note that the two function types above are unique because the parameter has
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]739 a different attribute (sext in the first one, zext in the second). Also note
740 that the attribute for the function result (zext) comes immediately after the
741 argument list.</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]742
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]743 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]744 <dl>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]745 <dt><tt>zext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]746 <dd>This indicates that the parameter should be zero extended just before
747 a call to this function.</dd>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]748 <dt><tt>sext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]749 <dd>This indicates that the parameter should be sign extended just before
750 a call to this function.</dd>
Anton Korobeynikove8166852007-01-28 14:30:45 +0000[diff] [blame]751 <dt><tt>inreg</tt></dt>
752 <dd>This indicates that the parameter should be placed in register (if
Anton Korobeynikove93c6e82007-01-28 15:27:21 +0000[diff] [blame]753 possible) during assembling function call. Support for this attribute is
754 target-specific</dd>
Anton Korobeynikove8166852007-01-28 14:30:45 +0000[diff] [blame]755 <dt><tt>sret</tt></dt>
Anton Korobeynikove93c6e82007-01-28 15:27:21 +0000[diff] [blame]756 <dd>This indicates that the parameter specifies the address of a structure
Reid Spencer05dbb9d2007-03-22 02:02:11 +0000[diff] [blame]757 that is the return value of the function in the source program.</dd>
Reid Spencer9d1700e2007-03-22 02:18:56 +0000[diff] [blame]758 <dt><tt>noreturn</tt></dt>
759 <dd>This function attribute indicates that the function never returns. This
760 indicates to LLVM that every call to this function should be treated as if
761 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Reid Spencer05dbb9d2007-03-22 02:02:11 +0000[diff] [blame]762 <dt><tt>nounwind</tt></dt>
763 <dd>This function attribute indicates that the function type does not use
764 the unwind instruction and does not allow stack unwinding to propagate
765 through it.</dd>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]766 </dl>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]767
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]768</div>
769
770<!-- ======================================================================= -->
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]771<div class="doc_subsection">
Chris Lattner93564892006-04-08 04:40:53 +0000[diff] [blame]772 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]773</div>
774
775<div class="doc_text">
776<p>
777Modules may contain "module-level inline asm" blocks, which corresponds to the
778GCC "file scope inline asm" blocks. These blocks are internally concatenated by
779LLVM and treated as a single unit, but may be separated in the .ll file if
780desired. The syntax is very simple:
781</p>
782
783<div class="doc_code"><pre>
Chris Lattnera1280ad2006-01-24 00:37:20 +0000[diff] [blame]784 module asm "inline asm code goes here"
785 module asm "more can go here"
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]786</pre></div>
787
788<p>The strings can contain any character by escaping non-printable characters.
789 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
790 for the number.
791</p>
792
793<p>
794 The inline asm code is simply printed to the machine code .s file when
795 assembly code is generated.
796</p>
797</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]798
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]799<!-- ======================================================================= -->
800<div class="doc_subsection">
801 <a name="datalayout">Data Layout</a>
802</div>
803
804<div class="doc_text">
805<p>A module may specify a target specific data layout string that specifies how
Reid Spencer7972c472007-04-11 23:49:50 +0000[diff] [blame]806data is to be laid out in memory. The syntax for the data layout is simply:</p>
807<pre> target datalayout = "<i>layout specification</i>"</pre>
808<p>The <i>layout specification</i> consists of a list of specifications
809separated by the minus sign character ('-'). Each specification starts with a
810letter and may include other information after the letter to define some
811aspect of the data layout. The specifications accepted are as follows: </p>
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]812<dl>
813 <dt><tt>E</tt></dt>
814 <dd>Specifies that the target lays out data in big-endian form. That is, the
815 bits with the most significance have the lowest address location.</dd>
816 <dt><tt>e</tt></dt>
817 <dd>Specifies that hte target lays out data in little-endian form. That is,
818 the bits with the least significance have the lowest address location.</dd>
819 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
820 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
821 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
822 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
823 too.</dd>
824 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
825 <dd>This specifies the alignment for an integer type of a given bit
826 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
827 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
828 <dd>This specifies the alignment for a vector type of a given bit
829 <i>size</i>.</dd>
830 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
831 <dd>This specifies the alignment for a floating point type of a given bit
832 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
833 (double).</dd>
834 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
835 <dd>This specifies the alignment for an aggregate type of a given bit
836 <i>size</i>.</dd>
837</dl>
838<p>When constructing the data layout for a given target, LLVM starts with a
839default set of specifications which are then (possibly) overriden by the
840specifications in the <tt>datalayout</tt> keyword. The default specifications
841are given in this list:</p>
842<ul>
843 <li><tt>E</tt> - big endian</li>
844 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
845 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
846 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
847 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
848 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
849 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
850 alignment of 64-bits</li>
851 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
852 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
853 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
854 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
855 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
856</ul>
857<p>When llvm is determining the alignment for a given type, it uses the
858following rules:
859<ol>
860 <li>If the type sought is an exact match for one of the specifications, that
861 specification is used.</li>
862 <li>If no match is found, and the type sought is an integer type, then the
863 smallest integer type that is larger than the bitwidth of the sought type is
864 used. If none of the specifications are larger than the bitwidth then the the
865 largest integer type is used. For example, given the default specifications
866 above, the i7 type will use the alignment of i8 (next largest) while both
867 i65 and i256 will use the alignment of i64 (largest specified).</li>
868 <li>If no match is found, and the type sought is a vector type, then the
869 largest vector type that is smaller than the sought vector type will be used
870 as a fall back. This happens because <128 x double> can be implemented in
871 terms of 64 <2 x double>, for example.</li>
872</ol>
873</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]874
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]875<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]876<div class="doc_section"> <a name="typesystem">Type System</a> </div>
877<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]878
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]879<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]880
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]881<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]882intermediate representation. Being typed enables a number of
883optimizations to be performed on the IR directly, without having to do
884extra analyses on the side before the transformation. A strong type
885system makes it easier to read the generated code and enables novel
886analyses and transformations that are not feasible to perform on normal
887three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]888
889</div>
890
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]891<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]892<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]893<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]894<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]895system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]896
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]897<table class="layout">
898 <tr class="layout">
899 <td class="left">
900 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]901 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]902 <tr><th>Type</th><th>Description</th></tr>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]903 <tr><td><tt><a name="t_void">void</a></tt></td><td>No value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]904 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
905 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]906 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]907 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]908 </tbody>
909 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]910 </td>
911 <td class="right">
912 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]913 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]914 <tr><th>Type</th><th>Description</th></tr>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]915 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]916 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
917 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]918 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]919 </tbody>
920 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]921 </td>
922 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]923</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]924</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]925
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]926<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]927<div class="doc_subsubsection"> <a name="t_classifications">Type
928Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]929<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]930<p>These different primitive types fall into a few useful
931classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]932
933<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]934 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]935 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]936 <tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]937 <td><a name="t_integer">integer</a></td>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]938 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]939 </tr>
940 <tr>
941 <td><a name="t_floating">floating point</a></td>
942 <td><tt>float, double</tt></td>
943 </tr>
944 <tr>
945 <td><a name="t_firstclass">first class</a></td>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]946 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]947 <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]948 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]949 </tr>
950 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]951</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]952
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]953<p>The <a href="#t_firstclass">first class</a> types are perhaps the
954most important. Values of these types are the only ones which can be
955produced by instructions, passed as arguments, or used as operands to
956instructions. This means that all structures and arrays must be
957manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]958</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]959
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]960<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]961<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]962
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]963<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]964
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]965<p>The real power in LLVM comes from the derived types in the system.
966This is what allows a programmer to represent arrays, functions,
967pointers, and other useful types. Note that these derived types may be
968recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]969
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]970</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]971
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]972<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]973<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]974
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]975<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]976
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]977<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]978
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]979<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]980sequentially in memory. The array type requires a size (number of
981elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]982
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]983<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]984
985<pre>
986 [&lt;# elements&gt; x &lt;elementtype&gt;]
987</pre>
988
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]989<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]990be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]991
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]992<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]993<table class="layout">
994 <tr class="layout">
995 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]996 <tt>[40 x i32 ]</tt><br/>
997 <tt>[41 x i32 ]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]998 <tt>[40 x i8]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]999 </td>
1000 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1001 Array of 40 32-bit integer values.<br/>
1002 Array of 41 32-bit integer values.<br/>
1003 Array of 40 8-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1004 </td>
1005 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1006</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1007<p>Here are some examples of multidimensional arrays:</p>
1008<table class="layout">
1009 <tr class="layout">
1010 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1011 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1012 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1013 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1014 </td>
1015 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1016 3x4 array of 32-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1017 12x10 array of single precision floating point values.<br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1018 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1019 </td>
1020 </tr>
1021</table>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1022
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1023<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1024length array. Normally, accesses past the end of an array are undefined in
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1025LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1026As a special case, however, zero length arrays are recognized to be variable
1027length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1028type "{ i32, [0 x float]}", for example.</p>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1029
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1030</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1031
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1032<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1033<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1034<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1035<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1036<p>The function type can be thought of as a function signature. It
1037consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]1038Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1039(which are structures of pointers to functions), for indirect function
1040calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]1041<p>
1042The return type of a function type cannot be an aggregate type.
1043</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1044<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1045<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1046<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]1047specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1048which indicates that the function takes a variable number of arguments.
1049Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1050 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1051<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1052<table class="layout">
1053 <tr class="layout">
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1054 <td class="left"><tt>i32 (i32)</tt></td>
1055 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1056 </td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1057 </tr><tr class="layout">
Reid Spencere6a338d2007-01-15 18:28:34 +0000[diff] [blame]1058 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencer655dcc62006-12-31 07:20:23 +0000[diff] [blame]1059 </tt></td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1060 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1061 an <tt>i16</tt> that should be sign extended and a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1062 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1063 <tt>float</tt>.
1064 </td>
1065 </tr><tr class="layout">
1066 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1067 <td class="left">A vararg function that takes at least one
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1068 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1069 which returns an integer. This is the signature for <tt>printf</tt> in
1070 LLVM.
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1071 </td>
1072 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1073</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1074
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1075</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1076<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1077<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1078<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1079<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1080<p>The structure type is used to represent a collection of data members
1081together in memory. The packing of the field types is defined to match
1082the ABI of the underlying processor. The elements of a structure may
1083be any type that has a size.</p>
1084<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1085and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1086field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1087instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1088<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1089<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1090<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1091<table class="layout">
1092 <tr class="layout">
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]1093 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1094 <td class="left">A triple of three <tt>i32</tt> values</td>
1095 </tr><tr class="layout">
1096 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1097 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1098 second element is a <a href="#t_pointer">pointer</a> to a
1099 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1100 an <tt>i32</tt>.</td>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1101 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1102</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1103</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1104
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1105<!-- _______________________________________________________________________ -->
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1106<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1107</div>
1108<div class="doc_text">
1109<h5>Overview:</h5>
1110<p>The packed structure type is used to represent a collection of data members
1111together in memory. There is no padding between fields. Further, the alignment
1112of a packed structure is 1 byte. The elements of a packed structure may
1113be any type that has a size.</p>
1114<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1115and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1116field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1117instruction.</p>
1118<h5>Syntax:</h5>
1119<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1120<h5>Examples:</h5>
1121<table class="layout">
1122 <tr class="layout">
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]1123 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1124 <td class="left">A triple of three <tt>i32</tt> values</td>
1125 </tr><tr class="layout">
1126 <td class="left"><tt>&lt;&nbsp;{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}&nbsp;&gt;</tt></td>
1127 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1128 second element is a <a href="#t_pointer">pointer</a> to a
1129 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1130 an <tt>i32</tt>.</td>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1131 </tr>
1132</table>
1133</div>
1134
1135<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1136<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1137<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1138<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1139<p>As in many languages, the pointer type represents a pointer or
1140reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1141<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1142<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1143<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1144<table class="layout">
1145 <tr class="layout">
1146 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1147 <tt>[4x i32]*</tt><br/>
1148 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1149 </td>
1150 <td class="left">
1151 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1152 four <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1153 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1154 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1155 <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1156 </td>
1157 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1158</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1159</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1160
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1161<!-- _______________________________________________________________________ -->
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1162<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1163<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1164
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1165<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1166
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1167<p>A vector type is a simple derived type that represents a vector
1168of elements. Vector types are used when multiple primitive data
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1169are operated in parallel using a single instruction (SIMD).
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1170A vector type requires a size (number of
Chris Lattner330ce692005-11-10 01:44:22 +0000[diff] [blame]1171elements) and an underlying primitive data type. Vectors must have a power
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1172of two length (1, 2, 4, 8, 16 ...). Vector types are
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1173considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1174
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1175<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1176
1177<pre>
1178 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1179</pre>
1180
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1181<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1182be any integer or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1183
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1184<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1185
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1186<table class="layout">
1187 <tr class="layout">
1188 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1189 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1190 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1191 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1192 </td>
1193 <td class="left">
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1194 Vector of 4 32-bit integer values.<br/>
1195 Vector of 8 floating-point values.<br/>
1196 Vector of 2 64-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1197 </td>
1198 </tr>
1199</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1200</div>
1201
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1202<!-- _______________________________________________________________________ -->
1203<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1204<div class="doc_text">
1205
1206<h5>Overview:</h5>
1207
1208<p>Opaque types are used to represent unknown types in the system. This
1209corresponds (for example) to the C notion of a foward declared structure type.
1210In LLVM, opaque types can eventually be resolved to any type (not just a
1211structure type).</p>
1212
1213<h5>Syntax:</h5>
1214
1215<pre>
1216 opaque
1217</pre>
1218
1219<h5>Examples:</h5>
1220
1221<table class="layout">
1222 <tr class="layout">
1223 <td class="left">
1224 <tt>opaque</tt>
1225 </td>
1226 <td class="left">
1227 An opaque type.<br/>
1228 </td>
1229 </tr>
1230</table>
1231</div>
1232
1233
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1234<!-- *********************************************************************** -->
1235<div class="doc_section"> <a name="constants">Constants</a> </div>
1236<!-- *********************************************************************** -->
1237
1238<div class="doc_text">
1239
1240<p>LLVM has several different basic types of constants. This section describes
1241them all and their syntax.</p>
1242
1243</div>
1244
1245<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1246<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1247
1248<div class="doc_text">
1249
1250<dl>
1251 <dt><b>Boolean constants</b></dt>
1252
1253 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1254 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1255 </dd>
1256
1257 <dt><b>Integer constants</b></dt>
1258
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1259 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1260 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1261 integer types.
1262 </dd>
1263
1264 <dt><b>Floating point constants</b></dt>
1265
1266 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1267 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1268 notation (see below). Floating point constants must have a <a
1269 href="#t_floating">floating point</a> type. </dd>
1270
1271 <dt><b>Null pointer constants</b></dt>
1272
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1273 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1274 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1275
1276</dl>
1277
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1278<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1279of floating point constants. For example, the form '<tt>double
12800x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
12814.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1282(and the only time that they are generated by the disassembler) is when a
1283floating point constant must be emitted but it cannot be represented as a
1284decimal floating point number. For example, NaN's, infinities, and other
1285special values are represented in their IEEE hexadecimal format so that
1286assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1287
1288</div>
1289
1290<!-- ======================================================================= -->
1291<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1292</div>
1293
1294<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1295<p>Aggregate constants arise from aggregation of simple constants
1296and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1297
1298<dl>
1299 <dt><b>Structure constants</b></dt>
1300
1301 <dd>Structure constants are represented with notation similar to structure
1302 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1303 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1304 where "<tt>%G</tt>" is declared as "<tt>%G = external global i32</tt>". Structure constants
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1305 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1306 types of elements must match those specified by the type.
1307 </dd>
1308
1309 <dt><b>Array constants</b></dt>
1310
1311 <dd>Array constants are represented with notation similar to array type
1312 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1313 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1314 constants must have <a href="#t_array">array type</a>, and the number and
1315 types of elements must match those specified by the type.
1316 </dd>
1317
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1318 <dt><b>Vector constants</b></dt>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1319
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1320 <dd>Vector constants are represented with notation similar to vector type
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1321 definitions (a comma separated list of elements, surrounded by
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1322 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]1323 i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must have <a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1324 href="#t_vector">vector type</a>, and the number and types of elements must
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1325 match those specified by the type.
1326 </dd>
1327
1328 <dt><b>Zero initialization</b></dt>
1329
1330 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1331 value to zero of <em>any</em> type, including scalar and aggregate types.
1332 This is often used to avoid having to print large zero initializers (e.g. for
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1333 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1334 initializers.
1335 </dd>
1336</dl>
1337
1338</div>
1339
1340<!-- ======================================================================= -->
1341<div class="doc_subsection">
1342 <a name="globalconstants">Global Variable and Function Addresses</a>
1343</div>
1344
1345<div class="doc_text">
1346
1347<p>The addresses of <a href="#globalvars">global variables</a> and <a
1348href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1349constants. These constants are explicitly referenced when the <a
1350href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1351href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1352file:</p>
1353
1354<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1355 %X = global i32 17
1356 %Y = global i32 42
1357 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1358</pre>
1359
1360</div>
1361
1362<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1363<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1364<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1365 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1366 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1367 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1368
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1369 <p>Undefined values indicate to the compiler that the program is well defined
1370 no matter what value is used, giving the compiler more freedom to optimize.
1371 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1372</div>
1373
1374<!-- ======================================================================= -->
1375<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1376</div>
1377
1378<div class="doc_text">
1379
1380<p>Constant expressions are used to allow expressions involving other constants
1381to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1382href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1383that does not have side effects (e.g. load and call are not supported). The
1384following is the syntax for constant expressions:</p>
1385
1386<dl>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1387 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1388 <dd>Truncate a constant to another type. The bit size of CST must be larger
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1389 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1390
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1391 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1392 <dd>Zero extend a constant to another type. The bit size of CST must be
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1393 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1394
1395 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1396 <dd>Sign extend a constant to another type. The bit size of CST must be
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1397 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1398
1399 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1400 <dd>Truncate a floating point constant to another floating point type. The
1401 size of CST must be larger than the size of TYPE. Both types must be
1402 floating point.</dd>
1403
1404 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1405 <dd>Floating point extend a constant to another type. The size of CST must be
1406 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1407
1408 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1409 <dd>Convert a floating point constant to the corresponding unsigned integer
1410 constant. TYPE must be an integer type. CST must be floating point. If the
1411 value won't fit in the integer type, the results are undefined.</dd>
1412
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1413 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1414 <dd>Convert a floating point constant to the corresponding signed integer
1415 constant. TYPE must be an integer type. CST must be floating point. If the
1416 value won't fit in the integer type, the results are undefined.</dd>
1417
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1418 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1419 <dd>Convert an unsigned integer constant to the corresponding floating point
1420 constant. TYPE must be floating point. CST must be of integer type. If the
Jeff Cohenbeccb742007-04-22 14:56:37 +0000[diff] [blame]1421 value won't fit in the floating point type, the results are undefined.</dd>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1422
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1423 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1424 <dd>Convert a signed integer constant to the corresponding floating point
1425 constant. TYPE must be floating point. CST must be of integer type. If the
Jeff Cohenbeccb742007-04-22 14:56:37 +0000[diff] [blame]1426 value won't fit in the floating point type, the results are undefined.</dd>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1427
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1428 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1429 <dd>Convert a pointer typed constant to the corresponding integer constant
1430 TYPE must be an integer type. CST must be of pointer type. The CST value is
1431 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1432
1433 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1434 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1435 pointer type. CST must be of integer type. The CST value is zero extended,
1436 truncated, or unchanged to make it fit in a pointer size. This one is
1437 <i>really</i> dangerous!</dd>
1438
1439 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1440 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1441 identical (same number of bits). The conversion is done as if the CST value
1442 was stored to memory and read back as TYPE. In other words, no bits change
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1443 with this operator, just the type. This can be used for conversion of
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1444 vector types to any other type, as long as they have the same bit width. For
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1445 pointers it is only valid to cast to another pointer type.
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1446 </dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1447
1448 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1449
1450 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1451 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1452 instruction, the index list may have zero or more indexes, which are required
1453 to make sense for the type of "CSTPTR".</dd>
1454
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1455 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1456
1457 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1458 constants.</dd>
1459
1460 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1461 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1462
1463 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1464 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1465
1466 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1467
1468 <dd>Perform the <a href="#i_extractelement">extractelement
1469 operation</a> on constants.
1470
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1471 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1472
1473 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1474 operation</a> on constants.</dd>
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1475
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1476
1477 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1478
1479 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1480 operation</a> on constants.</dd>
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1481
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1482 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1483
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1484 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1485 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1486 binary</a> operations. The constraints on operands are the same as those for
1487 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1488 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1489</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1490</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1491
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1492<!-- *********************************************************************** -->
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1493<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1494<!-- *********************************************************************** -->
1495
1496<!-- ======================================================================= -->
1497<div class="doc_subsection">
1498<a name="inlineasm">Inline Assembler Expressions</a>
1499</div>
1500
1501<div class="doc_text">
1502
1503<p>
1504LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1505Module-Level Inline Assembly</a>) through the use of a special value. This
1506value represents the inline assembler as a string (containing the instructions
1507to emit), a list of operand constraints (stored as a string), and a flag that
1508indicates whether or not the inline asm expression has side effects. An example
1509inline assembler expression is:
1510</p>
1511
1512<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1513 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1514</pre>
1515
1516<p>
1517Inline assembler expressions may <b>only</b> be used as the callee operand of
1518a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1519</p>
1520
1521<pre>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]1522 %X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1523</pre>
1524
1525<p>
1526Inline asms with side effects not visible in the constraint list must be marked
1527as having side effects. This is done through the use of the
1528'<tt>sideeffect</tt>' keyword, like so:
1529</p>
1530
1531<pre>
1532 call void asm sideeffect "eieio", ""()
1533</pre>
1534
1535<p>TODO: The format of the asm and constraints string still need to be
1536documented here. Constraints on what can be done (e.g. duplication, moving, etc
1537need to be documented).
1538</p>
1539
1540</div>
1541
1542<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1543<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1544<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1545
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1546<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1547
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1548<p>The LLVM instruction set consists of several different
1549classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1550instructions</a>, <a href="#binaryops">binary instructions</a>,
1551<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1552 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1553instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1554
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1555</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1556
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1557<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1558<div class="doc_subsection"> <a name="terminators">Terminator
1559Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1560
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1561<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1562
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1563<p>As mentioned <a href="#functionstructure">previously</a>, every
1564basic block in a program ends with a "Terminator" instruction, which
1565indicates which block should be executed after the current block is
1566finished. These terminator instructions typically yield a '<tt>void</tt>'
1567value: they produce control flow, not values (the one exception being
1568the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1569<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1570 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1571instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1572the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1573 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1574 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1575
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1576</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1577
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1578<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1579<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1580Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1581<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1582<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1583<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1584 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1585</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1586<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1587<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1588value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1589<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1590returns a value and then causes control flow, and one that just causes
1591control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1592<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1593<p>The '<tt>ret</tt>' instruction may return any '<a
1594 href="#t_firstclass">first class</a>' type. Notice that a function is
1595not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1596instruction inside of the function that returns a value that does not
1597match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1598<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1599<p>When the '<tt>ret</tt>' instruction is executed, control flow
1600returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1601 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1602the instruction after the call. If the caller was an "<a
1603 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1604at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1605returns a value, that value shall set the call or invoke instruction's
1606return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1607<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1608<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1609 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1610</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1611</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1612<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1613<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1614<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1615<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1616<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1617</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1618<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1619<p>The '<tt>br</tt>' instruction is used to cause control flow to
1620transfer to a different basic block in the current function. There are
1621two forms of this instruction, corresponding to a conditional branch
1622and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1623<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1624<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1625single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]1626unconditional form of the '<tt>br</tt>' instruction takes a single
1627'<tt>label</tt>' value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1628<h5>Semantics:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1629<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1630argument is evaluated. If the value is <tt>true</tt>, control flows
1631to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1632control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1633<h5>Example:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1634<pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq, i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1635 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1636</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1637<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1638<div class="doc_subsubsection">
1639 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1640</div>
1641
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1642<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1643<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1644
1645<pre>
1646 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1647</pre>
1648
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1649<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1650
1651<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1652several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1653instruction, allowing a branch to occur to one of many possible
1654destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1655
1656
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1657<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1658
1659<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1660comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1661an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1662table is not allowed to contain duplicate constant entries.</p>
1663
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1664<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1665
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1666<p>The <tt>switch</tt> instruction specifies a table of values and
1667destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1668table is searched for the given value. If the value is found, control flow is
1669transfered to the corresponding destination; otherwise, control flow is
1670transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1671
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1672<h5>Implementation:</h5>
1673
1674<p>Depending on properties of the target machine and the particular
1675<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1676ways. For example, it could be generated as a series of chained conditional
1677branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1678
1679<h5>Example:</h5>
1680
1681<pre>
1682 <i>; Emulate a conditional br instruction</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1683 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1684 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1685
1686 <i>; Emulate an unconditional br instruction</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1687 switch i32 0, label %dest [ ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1688
1689 <i>; Implement a jump table:</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1690 switch i32 %val, label %otherwise [ i32 0, label %onzero
1691 i32 1, label %onone
1692 i32 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1693</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1694</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1695
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1696<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1697<div class="doc_subsubsection">
1698 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1699</div>
1700
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1701<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1702
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1703<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1704
1705<pre>
1706 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
Chris Lattner6b7a0082006-05-14 18:23:06 +0000[diff] [blame]1707 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1708</pre>
1709
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1710<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1711
1712<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1713function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1714'<tt>normal</tt>' label or the
1715'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1716"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1717"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1718href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1719continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1720
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1721<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1722
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1723<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1724
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1725<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1726 <li>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]1727 The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1728 convention</a> the call should use. If none is specified, the call defaults
1729 to using C calling conventions.
1730 </li>
1731 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1732 function value being invoked. In most cases, this is a direct function
1733 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1734 an arbitrary pointer to function value.
1735 </li>
1736
1737 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1738 function to be invoked. </li>
1739
1740 <li>'<tt>function args</tt>': argument list whose types match the function
1741 signature argument types. If the function signature indicates the function
1742 accepts a variable number of arguments, the extra arguments can be
1743 specified. </li>
1744
1745 <li>'<tt>normal label</tt>': the label reached when the called function
1746 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1747
1748 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1749 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1750
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1751</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1752
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1753<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1754
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1755<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1756href="#i_call">call</a></tt>' instruction in most regards. The primary
1757difference is that it establishes an association with a label, which is used by
1758the runtime library to unwind the stack.</p>
1759
1760<p>This instruction is used in languages with destructors to ensure that proper
1761cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1762exception. Additionally, this is important for implementation of
1763'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1764
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1765<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1766<pre>
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]1767 %retval = invoke i32 %Test(i32 15) to label %Continue
1768 unwind label %TestCleanup <i>; {i32}:retval set</i>
1769 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1770 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1771</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1772</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1773
1774
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1775<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1776
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1777<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1778Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1779
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1780<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1781
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1782<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1783<pre>
1784 unwind
1785</pre>
1786
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1787<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1788
1789<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1790at the first callee in the dynamic call stack which used an <a
1791href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1792primarily used to implement exception handling.</p>
1793
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1794<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1795
1796<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1797immediately halt. The dynamic call stack is then searched for the first <a
1798href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1799execution continues at the "exceptional" destination block specified by the
1800<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1801dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1802</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1803
1804<!-- _______________________________________________________________________ -->
1805
1806<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1807Instruction</a> </div>
1808
1809<div class="doc_text">
1810
1811<h5>Syntax:</h5>
1812<pre>
1813 unreachable
1814</pre>
1815
1816<h5>Overview:</h5>
1817
1818<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1819instruction is used to inform the optimizer that a particular portion of the
1820code is not reachable. This can be used to indicate that the code after a
1821no-return function cannot be reached, and other facts.</p>
1822
1823<h5>Semantics:</h5>
1824
1825<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1826</div>
1827
1828
1829
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1830<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1831<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1832<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1833<p>Binary operators are used to do most of the computation in a
1834program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1835produce a single value. The operands might represent
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1836multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1837The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1838necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1839<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1840</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1841<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1842<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1843Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1844<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1845<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1846<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1847</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1848<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1849<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1850<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1851<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1852 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1853 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1854Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1855<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1856<p>The value produced is the integer or floating point sum of the two
1857operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1858<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1859<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1860</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1861</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1862<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1863<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1864Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1865<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1866<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1867<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1868</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1869<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1870<p>The '<tt>sub</tt>' instruction returns the difference of its two
1871operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1872<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1873instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1874<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1875<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1876 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1877values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1878This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1879Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1880<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1881<p>The value produced is the integer or floating point difference of
1882the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1883<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1884<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1885 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1886</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1887</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1888<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1889<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1890Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1891<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1892<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1893<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1894</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1895<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1896<p>The '<tt>mul</tt>' instruction returns the product of its two
1897operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1898<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1899<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1900 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1901values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1902This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1903Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1904<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1905<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1906two operands.</p>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1907<p>Because the operands are the same width, the result of an integer
1908multiplication is the same whether the operands should be deemed unsigned or
1909signed.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1910<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1911<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1912</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1913</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1914<!-- _______________________________________________________________________ -->
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1915<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1916</a></div>
1917<div class="doc_text">
1918<h5>Syntax:</h5>
1919<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1920</pre>
1921<h5>Overview:</h5>
1922<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1923operands.</p>
1924<h5>Arguments:</h5>
1925<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1926<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1927types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1928of the values in which case the elements must be integers.</p>
1929<h5>Semantics:</h5>
1930<p>The value produced is the unsigned integer quotient of the two operands. This
1931instruction always performs an unsigned division operation, regardless of
1932whether the arguments are unsigned or not.</p>
1933<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1934<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1935</pre>
1936</div>
1937<!-- _______________________________________________________________________ -->
1938<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1939</a> </div>
1940<div class="doc_text">
1941<h5>Syntax:</h5>
1942<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1943</pre>
1944<h5>Overview:</h5>
1945<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1946operands.</p>
1947<h5>Arguments:</h5>
1948<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1949<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1950types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1951of the values in which case the elements must be integers.</p>
1952<h5>Semantics:</h5>
1953<p>The value produced is the signed integer quotient of the two operands. This
1954instruction always performs a signed division operation, regardless of whether
1955the arguments are signed or not.</p>
1956<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1957<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1958</pre>
1959</div>
1960<!-- _______________________________________________________________________ -->
1961<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1962Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1963<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1964<h5>Syntax:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1965<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1966</pre>
1967<h5>Overview:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1968<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1969operands.</p>
1970<h5>Arguments:</h5>
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]1971<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1972<a href="#t_floating">floating point</a> values. Both arguments must have
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1973identical types. This instruction can also take <a href="#t_vector">vector</a>
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]1974versions of floating point values.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1975<h5>Semantics:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1976<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1977<h5>Example:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1978<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1979</pre>
1980</div>
1981<!-- _______________________________________________________________________ -->
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1982<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1983</div>
1984<div class="doc_text">
1985<h5>Syntax:</h5>
1986<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1987</pre>
1988<h5>Overview:</h5>
1989<p>The '<tt>urem</tt>' instruction returns the remainder from the
1990unsigned division of its two arguments.</p>
1991<h5>Arguments:</h5>
1992<p>The two arguments to the '<tt>urem</tt>' instruction must be
1993<a href="#t_integer">integer</a> values. Both arguments must have identical
1994types.</p>
1995<h5>Semantics:</h5>
1996<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1997This instruction always performs an unsigned division to get the remainder,
1998regardless of whether the arguments are unsigned or not.</p>
1999<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2000<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2001</pre>
2002
2003</div>
2004<!-- _______________________________________________________________________ -->
2005<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2006Instruction</a> </div>
2007<div class="doc_text">
2008<h5>Syntax:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2009<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2010</pre>
2011<h5>Overview:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2012<p>The '<tt>srem</tt>' instruction returns the remainder from the
2013signed division of its two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2014<h5>Arguments:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2015<p>The two arguments to the '<tt>srem</tt>' instruction must be
2016<a href="#t_integer">integer</a> values. Both arguments must have identical
2017types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2018<h5>Semantics:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2019<p>This instruction returns the <i>remainder</i> of a division (where the result
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2020has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2021operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2022a value. For more information about the difference, see <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2023 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2024Math Forum</a>. For a table of how this is implemented in various languages,
Reid Spencerdb3b93b2007-03-24 22:40:44 +0000[diff] [blame]2025please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2026Wikipedia: modulo operation</a>.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2027<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2028<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2029</pre>
2030
2031</div>
2032<!-- _______________________________________________________________________ -->
2033<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2034Instruction</a> </div>
2035<div class="doc_text">
2036<h5>Syntax:</h5>
2037<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2038</pre>
2039<h5>Overview:</h5>
2040<p>The '<tt>frem</tt>' instruction returns the remainder from the
2041division of its two operands.</p>
2042<h5>Arguments:</h5>
2043<p>The two arguments to the '<tt>frem</tt>' instruction must be
2044<a href="#t_floating">floating point</a> values. Both arguments must have
2045identical types.</p>
2046<h5>Semantics:</h5>
2047<p>This instruction returns the <i>remainder</i> of a division.</p>
2048<h5>Example:</h5>
2049<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2050</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2051</div>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]2052
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]2053<!-- ======================================================================= -->
2054<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2055Operations</a> </div>
2056<div class="doc_text">
2057<p>Bitwise binary operators are used to do various forms of
2058bit-twiddling in a program. They are generally very efficient
2059instructions and can commonly be strength reduced from other
2060instructions. They require two operands, execute an operation on them,
2061and produce a single value. The resulting value of the bitwise binary
2062operators is always the same type as its first operand.</p>
2063</div>
2064
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2065<!-- _______________________________________________________________________ -->
2066<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2067Instruction</a> </div>
2068<div class="doc_text">
2069<h5>Syntax:</h5>
2070<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2071</pre>
2072<h5>Overview:</h5>
2073<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2074the left a specified number of bits.</p>
2075<h5>Arguments:</h5>
2076<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2077 href="#t_integer">integer</a> type.</p>
2078<h5>Semantics:</h5>
2079<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
2080<h5>Example:</h5><pre>
2081 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2082 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2083 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
2084</pre>
2085</div>
2086<!-- _______________________________________________________________________ -->
2087<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2088Instruction</a> </div>
2089<div class="doc_text">
2090<h5>Syntax:</h5>
2091<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2092</pre>
2093
2094<h5>Overview:</h5>
2095<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2096operand shifted to the right a specified number of bits with zero fill.</p>
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2097
2098<h5>Arguments:</h5>
2099<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2100<a href="#t_integer">integer</a> type.</p>
2101
2102<h5>Semantics:</h5>
2103<p>This instruction always performs a logical shift right operation. The most
2104significant bits of the result will be filled with zero bits after the
2105shift.</p>
2106
2107<h5>Example:</h5>
2108<pre>
2109 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2110 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2111 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2112 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2113</pre>
2114</div>
2115
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]2116<!-- _______________________________________________________________________ -->
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2117<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2118Instruction</a> </div>
2119<div class="doc_text">
2120
2121<h5>Syntax:</h5>
2122<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2123</pre>
2124
2125<h5>Overview:</h5>
2126<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2127operand shifted to the right a specified number of bits with sign extension.</p>
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2128
2129<h5>Arguments:</h5>
2130<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2131<a href="#t_integer">integer</a> type.</p>
2132
2133<h5>Semantics:</h5>
2134<p>This instruction always performs an arithmetic shift right operation,
2135The most significant bits of the result will be filled with the sign bit
2136of <tt>var1</tt>.</p>
2137
2138<h5>Example:</h5>
2139<pre>
2140 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2141 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2142 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2143 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
2144</pre>
2145</div>
2146
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2147<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2148<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2149Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2150<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2151<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2152<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2153</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2154<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2155<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2156its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2157<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2158<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2159 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2160identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2161<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2162<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2163<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2164<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2165<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2166 <tbody>
2167 <tr>
2168 <td>In0</td>
2169 <td>In1</td>
2170 <td>Out</td>
2171 </tr>
2172 <tr>
2173 <td>0</td>
2174 <td>0</td>
2175 <td>0</td>
2176 </tr>
2177 <tr>
2178 <td>0</td>
2179 <td>1</td>
2180 <td>0</td>
2181 </tr>
2182 <tr>
2183 <td>1</td>
2184 <td>0</td>
2185 <td>0</td>
2186 </tr>
2187 <tr>
2188 <td>1</td>
2189 <td>1</td>
2190 <td>1</td>
2191 </tr>
2192 </tbody>
2193</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2194</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2195<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2196<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2197 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2198 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2199</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2200</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2201<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2202<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2203<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2204<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2205<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2206</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2207<h5>Overview:</h5>
2208<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2209or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2210<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2211<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2212 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2213identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2214<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2215<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2216<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2217<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2218<table border="1" cellspacing="0" cellpadding="4">
2219 <tbody>
2220 <tr>
2221 <td>In0</td>
2222 <td>In1</td>
2223 <td>Out</td>
2224 </tr>
2225 <tr>
2226 <td>0</td>
2227 <td>0</td>
2228 <td>0</td>
2229 </tr>
2230 <tr>
2231 <td>0</td>
2232 <td>1</td>
2233 <td>1</td>
2234 </tr>
2235 <tr>
2236 <td>1</td>
2237 <td>0</td>
2238 <td>1</td>
2239 </tr>
2240 <tr>
2241 <td>1</td>
2242 <td>1</td>
2243 <td>1</td>
2244 </tr>
2245 </tbody>
2246</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2247</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2248<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2249<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2250 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2251 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2252</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2253</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2254<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2255<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2256Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2257<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2258<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2259<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2260</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2261<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2262<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2263or of its two operands. The <tt>xor</tt> is used to implement the
2264"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2265<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2266<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2267 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2268identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2269<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2270<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2271<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2272<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2273<table border="1" cellspacing="0" cellpadding="4">
2274 <tbody>
2275 <tr>
2276 <td>In0</td>
2277 <td>In1</td>
2278 <td>Out</td>
2279 </tr>
2280 <tr>
2281 <td>0</td>
2282 <td>0</td>
2283 <td>0</td>
2284 </tr>
2285 <tr>
2286 <td>0</td>
2287 <td>1</td>
2288 <td>1</td>
2289 </tr>
2290 <tr>
2291 <td>1</td>
2292 <td>0</td>
2293 <td>1</td>
2294 </tr>
2295 <tr>
2296 <td>1</td>
2297 <td>1</td>
2298 <td>0</td>
2299 </tr>
2300 </tbody>
2301</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2302</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2303<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2304<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2305<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2306 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2307 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2308 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2309</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2310</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2311
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2312<!-- ======================================================================= -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2313<div class="doc_subsection">
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2314 <a name="vectorops">Vector Operations</a>
2315</div>
2316
2317<div class="doc_text">
2318
2319<p>LLVM supports several instructions to represent vector operations in a
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2320target-independent manner. These instructions cover the element-access and
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2321vector-specific operations needed to process vectors effectively. While LLVM
2322does directly support these vector operations, many sophisticated algorithms
2323will want to use target-specific intrinsics to take full advantage of a specific
2324target.</p>
2325
2326</div>
2327
2328<!-- _______________________________________________________________________ -->
2329<div class="doc_subsubsection">
2330 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2331</div>
2332
2333<div class="doc_text">
2334
2335<h5>Syntax:</h5>
2336
2337<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2338 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2339</pre>
2340
2341<h5>Overview:</h5>
2342
2343<p>
2344The '<tt>extractelement</tt>' instruction extracts a single scalar
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2345element from a vector at a specified index.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2346</p>
2347
2348
2349<h5>Arguments:</h5>
2350
2351<p>
2352The first operand of an '<tt>extractelement</tt>' instruction is a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2353value of <a href="#t_vector">vector</a> type. The second operand is
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2354an index indicating the position from which to extract the element.
2355The index may be a variable.</p>
2356
2357<h5>Semantics:</h5>
2358
2359<p>
2360The result is a scalar of the same type as the element type of
2361<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2362<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2363results are undefined.
2364</p>
2365
2366<h5>Example:</h5>
2367
2368<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2369 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2370</pre>
2371</div>
2372
2373
2374<!-- _______________________________________________________________________ -->
2375<div class="doc_subsubsection">
2376 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2377</div>
2378
2379<div class="doc_text">
2380
2381<h5>Syntax:</h5>
2382
2383<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2384 &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>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2385</pre>
2386
2387<h5>Overview:</h5>
2388
2389<p>
2390The '<tt>insertelement</tt>' instruction inserts a scalar
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2391element into a vector at a specified index.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2392</p>
2393
2394
2395<h5>Arguments:</h5>
2396
2397<p>
2398The first operand of an '<tt>insertelement</tt>' instruction is a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2399value of <a href="#t_vector">vector</a> type. The second operand is a
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2400scalar value whose type must equal the element type of the first
2401operand. The third operand is an index indicating the position at
2402which to insert the value. The index may be a variable.</p>
2403
2404<h5>Semantics:</h5>
2405
2406<p>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2407The result is a vector of the same type as <tt>val</tt>. Its
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2408element values are those of <tt>val</tt> except at position
2409<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2410exceeds the length of <tt>val</tt>, the results are undefined.
2411</p>
2412
2413<h5>Example:</h5>
2414
2415<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2416 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2417</pre>
2418</div>
2419
2420<!-- _______________________________________________________________________ -->
2421<div class="doc_subsubsection">
2422 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2423</div>
2424
2425<div class="doc_text">
2426
2427<h5>Syntax:</h5>
2428
2429<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2430 &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;n x i32&gt; &lt;mask&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2431</pre>
2432
2433<h5>Overview:</h5>
2434
2435<p>
2436The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2437from two input vectors, returning a vector of the same type.
2438</p>
2439
2440<h5>Arguments:</h5>
2441
2442<p>
2443The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2444with types that match each other and types that match the result of the
2445instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2446of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2447</p>
2448
2449<p>
2450The shuffle mask operand is required to be a constant vector with either
2451constant integer or undef values.
2452</p>
2453
2454<h5>Semantics:</h5>
2455
2456<p>
2457The elements of the two input vectors are numbered from left to right across
2458both of the vectors. The shuffle mask operand specifies, for each element of
2459the result vector, which element of the two input registers the result element
2460gets. The element selector may be undef (meaning "don't care") and the second
2461operand may be undef if performing a shuffle from only one vector.
2462</p>
2463
2464<h5>Example:</h5>
2465
2466<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2467 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2468 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2469 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2470 &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.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2471</pre>
2472</div>
2473
Tanya Lattnerb138bbe2006-04-14 19:24:33 +0000[diff] [blame]2474
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2475<!-- ======================================================================= -->
2476<div class="doc_subsection">
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2477 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2478</div>
2479
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2480<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2481
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2482<p>A key design point of an SSA-based representation is how it
2483represents memory. In LLVM, no memory locations are in SSA form, which
2484makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2485allocate, and free memory in LLVM.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2486
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2487</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2488
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2489<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2490<div class="doc_subsubsection">
2491 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2492</div>
2493
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2494<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2495
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2496<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2497
2498<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2499 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2500</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2501
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2502<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2503
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2504<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2505heap and returns a pointer to it.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2506
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2507<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2508
2509<p>The '<tt>malloc</tt>' instruction allocates
2510<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]2511bytes of memory from the operating system and returns a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2512appropriate type to the program. If "NumElements" is specified, it is the
2513number of elements allocated. If an alignment is specified, the value result
2514of the allocation is guaranteed to be aligned to at least that boundary. If
2515not specified, or if zero, the target can choose to align the allocation on any
2516convenient boundary.</p>
2517
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2518<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2519
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2520<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2521
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2522<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2523a pointer is returned.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2524
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2525<h5>Example:</h5>
2526
2527<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2528 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2529
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2530 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2531 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2532 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2533 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2534 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2535</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2536</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2537
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2538<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2539<div class="doc_subsubsection">
2540 <a name="i_free">'<tt>free</tt>' Instruction</a>
2541</div>
2542
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2543<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2544
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2545<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2546
2547<pre>
2548 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2549</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2550
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2551<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2552
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2553<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2554memory heap to be reallocated in the future.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2555
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2556<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2557
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2558<p>'<tt>value</tt>' shall be a pointer value that points to a value
2559that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2560instruction.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2561
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2562<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2563
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2564<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2565after this instruction executes.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2566
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2567<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2568
2569<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2570 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2571 free [4 x i8]* %array
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2572</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2573</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2574
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2575<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2576<div class="doc_subsubsection">
2577 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2578</div>
2579
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2580<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2581
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2582<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2583
2584<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2585 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2586</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2587
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2588<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2589
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2590<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
2591currently executing function, to be automatically released when this function
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2592returns to its caller.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2593
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2594<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2595
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2596<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2597bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2598appropriate type to the program. If "NumElements" is specified, it is the
2599number of elements allocated. If an alignment is specified, the value result
2600of the allocation is guaranteed to be aligned to at least that boundary. If
2601not specified, or if zero, the target can choose to align the allocation on any
2602convenient boundary.</p>
2603
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2604<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2605
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2606<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2607
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2608<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2609memory is automatically released when the function returns. The '<tt>alloca</tt>'
2610instruction is commonly used to represent automatic variables that must
2611have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]2612 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2613instructions), the memory is reclaimed.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2614
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2615<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2616
2617<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2618 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2619 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2620 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2621 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2622</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2623</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2624
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2625<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2626<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2627Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2628<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2629<h5>Syntax:</h5>
Christopher Lambbff50202007-04-21 08:16:25 +0000[diff] [blame]2630<pre> &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]<br> &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]<br></pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2631<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2632<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2633<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2634<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2635address from which to load. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2636 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2637marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2638the number or order of execution of this <tt>load</tt> with other
2639volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2640instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2641<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2642<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2643<h5>Examples:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2644<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2645 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2646 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2647 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2648</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2649</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2650<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2651<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2652Instruction</a> </div>
Reid Spencera89fb182006-11-09 21:18:01 +0000[diff] [blame]2653<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2654<h5>Syntax:</h5>
Christopher Lambbff50202007-04-21 08:16:25 +0000[diff] [blame]2655<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2656 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2657</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2658<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2659<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2660<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2661<p>There are two arguments to the '<tt>store</tt>' instruction: a value
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2662to store and an address at which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2663operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2664operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2665optimizer is not allowed to modify the number or order of execution of
2666this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2667 href="#i_store">store</a></tt> instructions.</p>
2668<h5>Semantics:</h5>
2669<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2670at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2671<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2672<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2673 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2674 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2675 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2676</pre>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2677</div>
2678
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2679<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2680<div class="doc_subsubsection">
2681 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2682</div>
2683
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2684<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2685<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2686<pre>
2687 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2688</pre>
2689
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2690<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2691
2692<p>
2693The '<tt>getelementptr</tt>' instruction is used to get the address of a
2694subelement of an aggregate data structure.</p>
2695
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2696<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2697
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2698<p>This instruction takes a list of integer operands that indicate what
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2699elements of the aggregate object to index to. The actual types of the arguments
2700provided depend on the type of the first pointer argument. The
2701'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2702levels of a structure or to a specific index in an array. When indexing into a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2703structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2704into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2705be sign extended to 64-bit values.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2706
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2707<p>For example, let's consider a C code fragment and how it gets
2708compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2709
2710<pre>
2711 struct RT {
2712 char A;
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2713 i32 B[10][20];
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2714 char C;
2715 };
2716 struct ST {
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2717 i32 X;
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2718 double Y;
2719 struct RT Z;
2720 };
2721
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2722 define i32 *foo(struct ST *s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2723 return &amp;s[1].Z.B[5][13];
2724 }
2725</pre>
2726
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2727<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2728
2729<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2730 %RT = type { i8 , [10 x [20 x i32]], i8 }
2731 %ST = type { i32, double, %RT }
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2732
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2733 define i32* %foo(%ST* %s) {
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2734 entry:
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2735 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2736 ret i32* %reg
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2737 }
2738</pre>
2739
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2740<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2741
2742<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2743on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2744and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
Reid Spencerc0312692006-12-03 16:53:48 +0000[diff] [blame]2745<a href="#t_integer">integer</a> type but the value will always be sign extended
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2746to 64-bits. <a href="#t_struct">Structure</a> types require <tt>i32</tt>
Reid Spencerc0312692006-12-03 16:53:48 +0000[diff] [blame]2747<b>constants</b>.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2748
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2749<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2750type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2751}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2752the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2753i8 }</tt>' type, another structure. The third index indexes into the second
2754element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2755array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2756'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2757to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2758
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2759<p>Note that it is perfectly legal to index partially through a
2760structure, returning a pointer to an inner element. Because of this,
2761the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2762
2763<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2764 define i32* %foo(%ST* %s) {
2765 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
Jeff Cohen5819f182007-04-22 01:17:39 +0000[diff] [blame]2766 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2767 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2768 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2769 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2770 ret i32* %t5
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2771 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2772</pre>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2773
2774<p>Note that it is undefined to access an array out of bounds: array and
2775pointer indexes must always be within the defined bounds of the array type.
2776The one exception for this rules is zero length arrays. These arrays are
2777defined to be accessible as variable length arrays, which requires access
2778beyond the zero'th element.</p>
2779
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2780<p>The getelementptr instruction is often confusing. For some more insight
2781into how it works, see <a href="GetElementPtr.html">the getelementptr
2782FAQ</a>.</p>
2783
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2784<h5>Example:</h5>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2785
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2786<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2787 <i>; yields [12 x i8]*:aptr</i>
2788 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2789</pre>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2790</div>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2791
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2792<!-- ======================================================================= -->
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2793<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2794</div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2795<div class="doc_text">
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2796<p>The instructions in this category are the conversion instructions (casting)
2797which all take a single operand and a type. They perform various bit conversions
2798on the operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2799</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2800
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2801<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2802<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2803 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2804</div>
2805<div class="doc_text">
2806
2807<h5>Syntax:</h5>
2808<pre>
2809 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2810</pre>
2811
2812<h5>Overview:</h5>
2813<p>
2814The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2815</p>
2816
2817<h5>Arguments:</h5>
2818<p>
2819The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2820be an <a href="#t_integer">integer</a> type, and a type that specifies the size
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2821and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2822type. The bit size of <tt>value</tt> must be larger than the bit size of
2823<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2824
2825<h5>Semantics:</h5>
2826<p>
2827The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2828and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2829larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2830It will always truncate bits.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2831
2832<h5>Example:</h5>
2833<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2834 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2835 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2836 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2837</pre>
2838</div>
2839
2840<!-- _______________________________________________________________________ -->
2841<div class="doc_subsubsection">
2842 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2843</div>
2844<div class="doc_text">
2845
2846<h5>Syntax:</h5>
2847<pre>
2848 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2849</pre>
2850
2851<h5>Overview:</h5>
2852<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2853<tt>ty2</tt>.</p>
2854
2855
2856<h5>Arguments:</h5>
2857<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2858<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2859also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2860<tt>value</tt> must be smaller than the bit size of the destination type,
2861<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2862
2863<h5>Semantics:</h5>
2864<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2865bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2866the operand and the type are the same size, no bit filling is done and the
2867cast is considered a <i>no-op cast</i> because no bits change (only the type
2868changes).</p>
2869
Reid Spencer07c9c682007-01-12 15:46:11 +0000[diff] [blame]2870<p>When zero extending from i1, the result will always be either 0 or 1.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2871
2872<h5>Example:</h5>
2873<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2874 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2875 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2876</pre>
2877</div>
2878
2879<!-- _______________________________________________________________________ -->
2880<div class="doc_subsubsection">
2881 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2882</div>
2883<div class="doc_text">
2884
2885<h5>Syntax:</h5>
2886<pre>
2887 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2888</pre>
2889
2890<h5>Overview:</h5>
2891<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2892
2893<h5>Arguments:</h5>
2894<p>
2895The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2896<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2897also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2898<tt>value</tt> must be smaller than the bit size of the destination type,
2899<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2900
2901<h5>Semantics:</h5>
2902<p>
2903The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2904bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2905the type <tt>ty2</tt>. When the the operand and the type are the same size,
2906no bit filling is done and the cast is considered a <i>no-op cast</i> because
2907no bits change (only the type changes).</p>
2908
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2909<p>When sign extending from i1, the extension always results in -1 or 0.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2910
2911<h5>Example:</h5>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2912<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2913 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2914 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2915</pre>
2916</div>
2917
2918<!-- _______________________________________________________________________ -->
2919<div class="doc_subsubsection">
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2920 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2921</div>
2922
2923<div class="doc_text">
2924
2925<h5>Syntax:</h5>
2926
2927<pre>
2928 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2929</pre>
2930
2931<h5>Overview:</h5>
2932<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2933<tt>ty2</tt>.</p>
2934
2935
2936<h5>Arguments:</h5>
2937<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2938 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2939cast it to. The size of <tt>value</tt> must be larger than the size of
2940<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2941<i>no-op cast</i>.</p>
2942
2943<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2944<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2945<a href="#t_floating">floating point</a> type to a smaller
2946<a href="#t_floating">floating point</a> type. If the value cannot fit within
2947the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2948
2949<h5>Example:</h5>
2950<pre>
2951 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2952 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2953</pre>
2954</div>
2955
2956<!-- _______________________________________________________________________ -->
2957<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2958 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2959</div>
2960<div class="doc_text">
2961
2962<h5>Syntax:</h5>
2963<pre>
2964 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2965</pre>
2966
2967<h5>Overview:</h5>
2968<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2969floating point value.</p>
2970
2971<h5>Arguments:</h5>
2972<p>The '<tt>fpext</tt>' instruction takes a
2973<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2974and a <a href="#t_floating">floating point</a> type to cast it to. The source
2975type must be smaller than the destination type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2976
2977<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2978<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]2979<a href="#t_floating">floating point</a> type to a larger
2980<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2981used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]2982<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2983
2984<h5>Example:</h5>
2985<pre>
2986 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2987 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2988</pre>
2989</div>
2990
2991<!-- _______________________________________________________________________ -->
2992<div class="doc_subsubsection">
Reid Spencer2eadb532007-01-21 00:29:26 +0000[diff] [blame]2993 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2994</div>
2995<div class="doc_text">
2996
2997<h5>Syntax:</h5>
2998<pre>
2999 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3000</pre>
3001
3002<h5>Overview:</h5>
3003<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
3004unsigned integer equivalent of type <tt>ty2</tt>.
3005</p>
3006
3007<h5>Arguments:</h5>
3008<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
3009<a href="#t_floating">floating point</a> value, and a type to cast it to, which
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3010must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3011
3012<h5>Semantics:</h5>
3013<p> The '<tt>fp2uint</tt>' instruction converts its
3014<a href="#t_floating">floating point</a> operand into the nearest (rounding
3015towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3016the results are undefined.</p>
3017
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3018<p>When converting to i1, the conversion is done as a comparison against
3019zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3020If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3021
3022<h5>Example:</h5>
3023<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3024 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
3025 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3026 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3027</pre>
3028</div>
3029
3030<!-- _______________________________________________________________________ -->
3031<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3032 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3033</div>
3034<div class="doc_text">
3035
3036<h5>Syntax:</h5>
3037<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3038 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3039</pre>
3040
3041<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3042<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3043<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3044</p>
3045
3046
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3047<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3048<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3049<a href="#t_floating">floating point</a> value, and a type to cast it to, which
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3050must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3051
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3052<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3053<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3054<a href="#t_floating">floating point</a> operand into the nearest (rounding
3055towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3056the results are undefined.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3057
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3058<p>When converting to i1, the conversion is done as a comparison against
3059zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3060If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3061
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3062<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3063<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3064 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
3065 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3066 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3067</pre>
3068</div>
3069
3070<!-- _______________________________________________________________________ -->
3071<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3072 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3073</div>
3074<div class="doc_text">
3075
3076<h5>Syntax:</h5>
3077<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3078 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3079</pre>
3080
3081<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3082<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3083integer and converts that value to the <tt>ty2</tt> type.</p>
3084
3085
3086<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3087<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be an
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3088<a href="#t_integer">integer</a> value, and a type to cast it to, which must
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3089be a <a href="#t_floating">floating point</a> type.</p>
3090
3091<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3092<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3093integer quantity and converts it to the corresponding floating point value. If
Jeff Cohenbeccb742007-04-22 14:56:37 +0000[diff] [blame]3094the value cannot fit in the floating point value, the results are undefined.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3095
3096
3097<h5>Example:</h5>
3098<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3099 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3100 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3101</pre>
3102</div>
3103
3104<!-- _______________________________________________________________________ -->
3105<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3106 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3107</div>
3108<div class="doc_text">
3109
3110<h5>Syntax:</h5>
3111<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3112 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3113</pre>
3114
3115<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3116<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3117integer and converts that value to the <tt>ty2</tt> type.</p>
3118
3119<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3120<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be an
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3121<a href="#t_integer">integer</a> value, and a type to cast it to, which must be
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3122a <a href="#t_floating">floating point</a> type.</p>
3123
3124<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3125<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3126integer quantity and converts it to the corresponding floating point value. If
Jeff Cohenbeccb742007-04-22 14:56:37 +0000[diff] [blame]3127the value cannot fit in the floating point value, the results are undefined.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3128
3129<h5>Example:</h5>
3130<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3131 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3132 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3133</pre>
3134</div>
3135
3136<!-- _______________________________________________________________________ -->
3137<div class="doc_subsubsection">
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3138 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3139</div>
3140<div class="doc_text">
3141
3142<h5>Syntax:</h5>
3143<pre>
3144 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3145</pre>
3146
3147<h5>Overview:</h5>
3148<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3149the integer type <tt>ty2</tt>.</p>
3150
3151<h5>Arguments:</h5>
3152<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3153must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3154<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3155
3156<h5>Semantics:</h5>
3157<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3158<tt>ty2</tt> by interpreting the pointer value as an integer and either
3159truncating or zero extending that value to the size of the integer type. If
3160<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3161<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3162are the same size, then nothing is done (<i>no-op cast</i>).</p>
3163
3164<h5>Example:</h5>
3165<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3166 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3167 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3168</pre>
3169</div>
3170
3171<!-- _______________________________________________________________________ -->
3172<div class="doc_subsubsection">
3173 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3174</div>
3175<div class="doc_text">
3176
3177<h5>Syntax:</h5>
3178<pre>
3179 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3180</pre>
3181
3182<h5>Overview:</h5>
3183<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3184a pointer type, <tt>ty2</tt>.</p>
3185
3186<h5>Arguments:</h5>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3187<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3188value to cast, and a type to cast it to, which must be a
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]3189<a href="#t_pointer">pointer</a> type.
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3190
3191<h5>Semantics:</h5>
3192<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3193<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3194the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3195size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3196the size of a pointer then a zero extension is done. If they are the same size,
3197nothing is done (<i>no-op cast</i>).</p>
3198
3199<h5>Example:</h5>
3200<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3201 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3202 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3203 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3204</pre>
3205</div>
3206
3207<!-- _______________________________________________________________________ -->
3208<div class="doc_subsubsection">
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3209 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3210</div>
3211<div class="doc_text">
3212
3213<h5>Syntax:</h5>
3214<pre>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3215 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3216</pre>
3217
3218<h5>Overview:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3219<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3220<tt>ty2</tt> without changing any bits.</p>
3221
3222<h5>Arguments:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3223<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3224a first class value, and a type to cast it to, which must also be a <a
3225 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencere3db84c2007-01-09 20:08:58 +0000[diff] [blame]3226and the destination type, <tt>ty2</tt>, must be identical. If the source
3227type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3228
3229<h5>Semantics:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3230<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3231<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3232this conversion. The conversion is done as if the <tt>value</tt> had been
3233stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3234converted to other pointer types with this instruction. To convert pointers to
3235other types, use the <a href="#i_inttoptr">inttoptr</a> or
3236<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3237
3238<h5>Example:</h5>
3239<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3240 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3241 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3242 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3243</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3244</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3245
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3246<!-- ======================================================================= -->
3247<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3248<div class="doc_text">
3249<p>The instructions in this category are the "miscellaneous"
3250instructions, which defy better classification.</p>
3251</div>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3252
3253<!-- _______________________________________________________________________ -->
3254<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3255</div>
3256<div class="doc_text">
3257<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3258<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3259<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3260</pre>
3261<h5>Overview:</h5>
3262<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3263of its two integer operands.</p>
3264<h5>Arguments:</h5>
3265<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3266the condition code which indicates the kind of comparison to perform. It is not
3267a value, just a keyword. The possibilities for the condition code are:
3268<ol>
3269 <li><tt>eq</tt>: equal</li>
3270 <li><tt>ne</tt>: not equal </li>
3271 <li><tt>ugt</tt>: unsigned greater than</li>
3272 <li><tt>uge</tt>: unsigned greater or equal</li>
3273 <li><tt>ult</tt>: unsigned less than</li>
3274 <li><tt>ule</tt>: unsigned less or equal</li>
3275 <li><tt>sgt</tt>: signed greater than</li>
3276 <li><tt>sge</tt>: signed greater or equal</li>
3277 <li><tt>slt</tt>: signed less than</li>
3278 <li><tt>sle</tt>: signed less or equal</li>
3279</ol>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3280<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3281<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3282<h5>Semantics:</h5>
3283<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3284the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3285yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3286<ol>
3287 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3288 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3289 </li>
3290 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3291 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3292 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3293 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3294 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3295 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3296 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3297 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3298 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3299 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3300 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3301 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3302 <li><tt>sge</tt>: interprets the operands as signed values and yields
3303 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3304 <li><tt>slt</tt>: interprets the operands as signed values and yields
3305 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3306 <li><tt>sle</tt>: interprets the operands as signed values and yields
3307 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3308</ol>
3309<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3310values are treated as integers and then compared.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3311
3312<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3313<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3314 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3315 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3316 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3317 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3318 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3319</pre>
3320</div>
3321
3322<!-- _______________________________________________________________________ -->
3323<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3324</div>
3325<div class="doc_text">
3326<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3327<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3328<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3329</pre>
3330<h5>Overview:</h5>
3331<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3332of its floating point operands.</p>
3333<h5>Arguments:</h5>
3334<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3335the condition code which indicates the kind of comparison to perform. It is not
3336a value, just a keyword. The possibilities for the condition code are:
3337<ol>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3338 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3339 <li><tt>oeq</tt>: ordered and equal</li>
3340 <li><tt>ogt</tt>: ordered and greater than </li>
3341 <li><tt>oge</tt>: ordered and greater than or equal</li>
3342 <li><tt>olt</tt>: ordered and less than </li>
3343 <li><tt>ole</tt>: ordered and less than or equal</li>
3344 <li><tt>one</tt>: ordered and not equal</li>
3345 <li><tt>ord</tt>: ordered (no nans)</li>
3346 <li><tt>ueq</tt>: unordered or equal</li>
3347 <li><tt>ugt</tt>: unordered or greater than </li>
3348 <li><tt>uge</tt>: unordered or greater than or equal</li>
3349 <li><tt>ult</tt>: unordered or less than </li>
3350 <li><tt>ule</tt>: unordered or less than or equal</li>
3351 <li><tt>une</tt>: unordered or not equal</li>
3352 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3353 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3354</ol>
Reid Spencer02e0d1d2006-12-06 07:08:07 +0000[diff] [blame]3355<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3356<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3357<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3358<a href="#t_floating">floating point</a> typed. They must have identical
3359types.</p>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3360<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3361<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3362<h5>Semantics:</h5>
3363<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3364the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3365yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3366<ol>
3367 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3368 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3369 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3370 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3371 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3372 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3373 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3374 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3375 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3376 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3377 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3378 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3379 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3380 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3381 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3382 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3383 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3384 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3385 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3386 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3387 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3388 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3389 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3390 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3391 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3392 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3393 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3394 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3395</ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3396
3397<h5>Example:</h5>
3398<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3399 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3400 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3401 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3402</pre>
3403</div>
3404
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3405<!-- _______________________________________________________________________ -->
3406<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3407Instruction</a> </div>
3408<div class="doc_text">
3409<h5>Syntax:</h5>
3410<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3411<h5>Overview:</h5>
3412<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3413the SSA graph representing the function.</p>
3414<h5>Arguments:</h5>
3415<p>The type of the incoming values are specified with the first type
3416field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3417as arguments, with one pair for each predecessor basic block of the
3418current block. Only values of <a href="#t_firstclass">first class</a>
3419type may be used as the value arguments to the PHI node. Only labels
3420may be used as the label arguments.</p>
3421<p>There must be no non-phi instructions between the start of a basic
3422block and the PHI instructions: i.e. PHI instructions must be first in
3423a basic block.</p>
3424<h5>Semantics:</h5>
3425<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3426value specified by the parameter, depending on which basic block we
3427came from in the last <a href="#terminators">terminator</a> instruction.</p>
3428<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3429<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add i32 %indvar, 1<br> br label %Loop<br></pre>
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3430</div>
3431
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3432<!-- _______________________________________________________________________ -->
3433<div class="doc_subsubsection">
3434 <a name="i_select">'<tt>select</tt>' Instruction</a>
3435</div>
3436
3437<div class="doc_text">
3438
3439<h5>Syntax:</h5>
3440
3441<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3442 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3443</pre>
3444
3445<h5>Overview:</h5>
3446
3447<p>
3448The '<tt>select</tt>' instruction is used to choose one value based on a
3449condition, without branching.
3450</p>
3451
3452
3453<h5>Arguments:</h5>
3454
3455<p>
3456The '<tt>select</tt>' instruction requires a boolean value indicating the condition, and two values of the same <a href="#t_firstclass">first class</a> type.
3457</p>
3458
3459<h5>Semantics:</h5>
3460
3461<p>
3462If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3463value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3464</p>
3465
3466<h5>Example:</h5>
3467
3468<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3469 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3470</pre>
3471</div>
3472
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]3473
3474<!-- _______________________________________________________________________ -->
3475<div class="doc_subsubsection">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3476 <a name="i_call">'<tt>call</tt>' Instruction</a>
3477</div>
3478
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3479<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3480
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3481<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3482<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3483 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3484</pre>
3485
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3486<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3487
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3488<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3489
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3490<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3491
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3492<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3493
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3494<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3495 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3496 <p>The optional "tail" marker indicates whether the callee function accesses
3497 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3498 function call is eligible for tail call optimization. Note that calls may
3499 be marked "tail" even if they do not occur before a <a
3500 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3501 </li>
3502 <li>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3503 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3504 convention</a> the call should use. If none is specified, the call defaults
3505 to using C calling conventions.
3506 </li>
3507 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3508 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3509 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3510 signature. This type can be omitted if the function is not varargs and
3511 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3512 </li>
3513 <li>
3514 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3515 be invoked. In most cases, this is a direct function invocation, but
3516 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3517 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3518 </li>
3519 <li>
3520 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]3521 function signature argument types. All arguments must be of
3522 <a href="#t_firstclass">first class</a> type. If the function signature
3523 indicates the function accepts a variable number of arguments, the extra
3524 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3525 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3526</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3527
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3528<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3529
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3530<p>The '<tt>call</tt>' instruction is used to cause control flow to
3531transfer to a specified function, with its incoming arguments bound to
3532the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3533instruction in the called function, control flow continues with the
3534instruction after the function call, and the return value of the
3535function is bound to the result argument. This is a simpler case of
3536the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3537
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3538<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3539
3540<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3541 %retval = call i32 %test(i32 %argc)
3542 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3543 %X = tail call i32 %foo()
3544 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3545</pre>
3546
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3547</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3548
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3549<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3550<div class="doc_subsubsection">
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3551 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3552</div>
3553
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3554<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3555
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3556<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3557
3558<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3559 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3560</pre>
3561
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3562<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3563
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3564<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3565the "variable argument" area of a function call. It is used to implement the
3566<tt>va_arg</tt> macro in C.</p>
3567
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3568<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3569
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3570<p>This instruction takes a <tt>va_list*</tt> value and the type of
3571the argument. It returns a value of the specified argument type and
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]3572increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3573actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3574
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3575<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3576
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3577<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3578type from the specified <tt>va_list</tt> and causes the
3579<tt>va_list</tt> to point to the next argument. For more information,
3580see the variable argument handling <a href="#int_varargs">Intrinsic
3581Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3582
3583<p>It is legal for this instruction to be called in a function which does not
3584take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3585function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3586
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3587<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3588href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3589argument.</p>
3590
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3591<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3592
3593<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3594
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3595</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3596
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3597<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3598<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3599<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3600
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3601<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3602
3603<p>LLVM supports the notion of an "intrinsic function". These functions have
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3604well known names and semantics and are required to follow certain restrictions.
3605Overall, these intrinsics represent an extension mechanism for the LLVM
3606language that does not require changing all of the transformations in LLVM to
3607add to the language (or the bytecode reader/writer, the parser,
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3608etc...).</p>
3609
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3610<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3611prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3612this. Intrinsic functions must always be external functions: you cannot define
3613the body of intrinsic functions. Intrinsic functions may only be used in call
3614or invoke instructions: it is illegal to take the address of an intrinsic
3615function. Additionally, because intrinsic functions are part of the LLVM
3616language, it is required that they all be documented here if any are added.</p>
3617
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3618<p>Some intrinsic functions can be overloaded. That is, the intrinsic represents
3619a family of functions that perform the same operation but on different data
3620types. This is most frequent with the integer types. Since LLVM can represent
3621over 8 million different integer types, there is a way to declare an intrinsic
3622that can be overloaded based on its arguments. Such intrinsics will have the
3623names of the arbitrary types encoded into the intrinsic function name, each
3624preceded by a period. For example, the <tt>llvm.ctpop</tt> function can take an
3625integer of any width. This leads to a family of functions such as
3626<tt>i32 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i32 @llvm.ctpop.i29(i29 %val)</tt>.
3627</p>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3628
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3629
3630<p>To learn how to add an intrinsic function, please see the
3631<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3632</p>
3633
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3634</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3635
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3636<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3637<div class="doc_subsection">
3638 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3639</div>
3640
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3641<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3642
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3643<p>Variable argument support is defined in LLVM with the <a
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3644 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3645intrinsic functions. These functions are related to the similarly
3646named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3647
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3648<p>All of these functions operate on arguments that use a
3649target-specific value type "<tt>va_list</tt>". The LLVM assembly
3650language reference manual does not define what this type is, so all
3651transformations should be prepared to handle intrinsics with any type
3652used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3653
Chris Lattner30b868d2006-05-15 17:26:46 +0000[diff] [blame]3654<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3655instruction and the variable argument handling intrinsic functions are
3656used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3657
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3658<pre>
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3659define i32 @test(i32 %X, ...) {
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3660 ; Initialize variable argument processing
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3661 %ap = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3662 %ap2 = bitcast i8** %ap to i8*
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3663 call void @llvm.va_start(i8* %ap2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3664
3665 ; Read a single integer argument
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3666 %tmp = va_arg i8 ** %ap, i32
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3667
3668 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3669 %aq = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3670 %aq2 = bitcast i8** %aq to i8*
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3671 call void @llvm.va_copy(i8 *%aq2, i8* %ap2)
3672 call void @llvm.va_end(i8* %aq2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3673
3674 ; Stop processing of arguments.
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3675 call void @llvm.va_end(i8* %ap2)
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3676 ret i32 %tmp
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3677}
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3678
3679declare void @llvm.va_start(i8*)
3680declare void @llvm.va_copy(i8*, i8*)
3681declare void @llvm.va_end(i8*)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3682</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3683</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3684
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3685<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3686<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3687 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3688</div>
3689
3690
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3691<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3692<h5>Syntax:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3693<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3694<h5>Overview:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3695<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3696<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3697href="#i_va_arg">va_arg</a></tt>.</p>
3698
3699<h5>Arguments:</h5>
3700
3701<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3702
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3703<h5>Semantics:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3704
3705<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3706macro available in C. In a target-dependent way, it initializes the
3707<tt>va_list</tt> element the argument points to, so that the next call to
3708<tt>va_arg</tt> will produce the first variable argument passed to the function.
3709Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3710last argument of the function, the compiler can figure that out.</p>
3711
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3712</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3713
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3714<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3715<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3716 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3717</div>
3718
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3719<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3720<h5>Syntax:</h5>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3721<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3722<h5>Overview:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3723
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3724<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3725which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3726or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3727
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3728<h5>Arguments:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3729
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3730<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3731
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3732<h5>Semantics:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3733
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3734<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3735macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3736Calls to <a href="#int_va_start"><tt>llvm.va_start</tt></a> and <a
3737 href="#int_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3738with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3739
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3740</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3741
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3742<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3743<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3744 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3745</div>
3746
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3747<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3748
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3749<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3750
3751<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3752 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3753</pre>
3754
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3755<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3756
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3757<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3758the source argument list to the destination argument list.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3759
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3760<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3761
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3762<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]3763The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3764
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3765
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3766<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3767
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3768<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3769available in C. In a target-dependent way, it copies the source
3770<tt>va_list</tt> element into the destination list. This intrinsic is necessary
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3771because the <tt><a href="#int_va_start">llvm.va_start</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3772arbitrarily complex and require memory allocation, for example.</p>
3773
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3774</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3775
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3776<!-- ======================================================================= -->
3777<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3778 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3779</div>
3780
3781<div class="doc_text">
3782
3783<p>
3784LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3785Collection</a> requires the implementation and generation of these intrinsics.
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3786These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3787stack</a>, as well as garbage collector implementations that require <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3788href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3789Front-ends for type-safe garbage collected languages should generate these
3790intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3791href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3792</p>
3793</div>
3794
3795<!-- _______________________________________________________________________ -->
3796<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3797 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3798</div>
3799
3800<div class="doc_text">
3801
3802<h5>Syntax:</h5>
3803
3804<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3805 declare void @llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3806</pre>
3807
3808<h5>Overview:</h5>
3809
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]3810<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3811the code generator, and allows some metadata to be associated with it.</p>
3812
3813<h5>Arguments:</h5>
3814
3815<p>The first argument specifies the address of a stack object that contains the
3816root pointer. The second pointer (which must be either a constant or a global
3817value address) contains the meta-data to be associated with the root.</p>
3818
3819<h5>Semantics:</h5>
3820
3821<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3822location. At compile-time, the code generator generates information to allow
3823the runtime to find the pointer at GC safe points.
3824</p>
3825
3826</div>
3827
3828
3829<!-- _______________________________________________________________________ -->
3830<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3831 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3832</div>
3833
3834<div class="doc_text">
3835
3836<h5>Syntax:</h5>
3837
3838<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3839 declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3840</pre>
3841
3842<h5>Overview:</h5>
3843
3844<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3845locations, allowing garbage collector implementations that require read
3846barriers.</p>
3847
3848<h5>Arguments:</h5>
3849
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3850<p>The second argument is the address to read from, which should be an address
3851allocated from the garbage collector. The first object is a pointer to the
3852start of the referenced object, if needed by the language runtime (otherwise
3853null).</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3854
3855<h5>Semantics:</h5>
3856
3857<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3858instruction, but may be replaced with substantially more complex code by the
3859garbage collector runtime, as needed.</p>
3860
3861</div>
3862
3863
3864<!-- _______________________________________________________________________ -->
3865<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3866 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3867</div>
3868
3869<div class="doc_text">
3870
3871<h5>Syntax:</h5>
3872
3873<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3874 declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3875</pre>
3876
3877<h5>Overview:</h5>
3878
3879<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3880locations, allowing garbage collector implementations that require write
3881barriers (such as generational or reference counting collectors).</p>
3882
3883<h5>Arguments:</h5>
3884
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3885<p>The first argument is the reference to store, the second is the start of the
3886object to store it to, and the third is the address of the field of Obj to
3887store to. If the runtime does not require a pointer to the object, Obj may be
3888null.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3889
3890<h5>Semantics:</h5>
3891
3892<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3893instruction, but may be replaced with substantially more complex code by the
3894garbage collector runtime, as needed.</p>
3895
3896</div>
3897
3898
3899
3900<!-- ======================================================================= -->
3901<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3902 <a name="int_codegen">Code Generator Intrinsics</a>
3903</div>
3904
3905<div class="doc_text">
3906<p>
3907These intrinsics are provided by LLVM to expose special features that may only
3908be implemented with code generator support.
3909</p>
3910
3911</div>
3912
3913<!-- _______________________________________________________________________ -->
3914<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3915 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3916</div>
3917
3918<div class="doc_text">
3919
3920<h5>Syntax:</h5>
3921<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3922 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3923</pre>
3924
3925<h5>Overview:</h5>
3926
3927<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3928The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3929target-specific value indicating the return address of the current function
3930or one of its callers.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3931</p>
3932
3933<h5>Arguments:</h5>
3934
3935<p>
3936The argument to this intrinsic indicates which function to return the address
3937for. Zero indicates the calling function, one indicates its caller, etc. The
3938argument is <b>required</b> to be a constant integer value.
3939</p>
3940
3941<h5>Semantics:</h5>
3942
3943<p>
3944The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3945the return address of the specified call frame, or zero if it cannot be
3946identified. The value returned by this intrinsic is likely to be incorrect or 0
3947for arguments other than zero, so it should only be used for debugging purposes.
3948</p>
3949
3950<p>
3951Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3952aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3953source-language caller.
3954</p>
3955</div>
3956
3957
3958<!-- _______________________________________________________________________ -->
3959<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3960 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3961</div>
3962
3963<div class="doc_text">
3964
3965<h5>Syntax:</h5>
3966<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3967 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3968</pre>
3969
3970<h5>Overview:</h5>
3971
3972<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3973The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3974target-specific frame pointer value for the specified stack frame.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3975</p>
3976
3977<h5>Arguments:</h5>
3978
3979<p>
3980The argument to this intrinsic indicates which function to return the frame
3981pointer for. Zero indicates the calling function, one indicates its caller,
3982etc. The argument is <b>required</b> to be a constant integer value.
3983</p>
3984
3985<h5>Semantics:</h5>
3986
3987<p>
3988The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3989the frame address of the specified call frame, or zero if it cannot be
3990identified. The value returned by this intrinsic is likely to be incorrect or 0
3991for arguments other than zero, so it should only be used for debugging purposes.
3992</p>
3993
3994<p>
3995Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3996aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3997source-language caller.
3998</p>
3999</div>
4000
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4001<!-- _______________________________________________________________________ -->
4002<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4003 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4004</div>
4005
4006<div class="doc_text">
4007
4008<h5>Syntax:</h5>
4009<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4010 declare i8 *@llvm.stacksave()
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4011</pre>
4012
4013<h5>Overview:</h5>
4014
4015<p>
4016The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4017the function stack, for use with <a href="#int_stackrestore">
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4018<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4019features like scoped automatic variable sized arrays in C99.
4020</p>
4021
4022<h5>Semantics:</h5>
4023
4024<p>
4025This intrinsic returns a opaque pointer value that can be passed to <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4026href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4027<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4028<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4029state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4030practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4031that were allocated after the <tt>llvm.stacksave</tt> was executed.
4032</p>
4033
4034</div>
4035
4036<!-- _______________________________________________________________________ -->
4037<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4038 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4039</div>
4040
4041<div class="doc_text">
4042
4043<h5>Syntax:</h5>
4044<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4045 declare void @llvm.stackrestore(i8 * %ptr)
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4046</pre>
4047
4048<h5>Overview:</h5>
4049
4050<p>
4051The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4052the function stack to the state it was in when the corresponding <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4053href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4054useful for implementing language features like scoped automatic variable sized
4055arrays in C99.
4056</p>
4057
4058<h5>Semantics:</h5>
4059
4060<p>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4061See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4062</p>
4063
4064</div>
4065
4066
4067<!-- _______________________________________________________________________ -->
4068<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4069 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4070</div>
4071
4072<div class="doc_text">
4073
4074<h5>Syntax:</h5>
4075<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4076 declare void @llvm.prefetch(i8 * &lt;address&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4077 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4078</pre>
4079
4080<h5>Overview:</h5>
4081
4082
4083<p>
4084The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4085a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4086no
4087effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]4088characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4089</p>
4090
4091<h5>Arguments:</h5>
4092
4093<p>
4094<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4095determining if the fetch should be for a read (0) or write (1), and
4096<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]4097locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4098<tt>locality</tt> arguments must be constant integers.
4099</p>
4100
4101<h5>Semantics:</h5>
4102
4103<p>
4104This intrinsic does not modify the behavior of the program. In particular,
4105prefetches cannot trap and do not produce a value. On targets that support this
4106intrinsic, the prefetch can provide hints to the processor cache for better
4107performance.
4108</p>
4109
4110</div>
4111
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4112<!-- _______________________________________________________________________ -->
4113<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4114 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4115</div>
4116
4117<div class="doc_text">
4118
4119<h5>Syntax:</h5>
4120<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4121 declare void @llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4122</pre>
4123
4124<h5>Overview:</h5>
4125
4126
4127<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4128The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4129(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4130code to simulators and other tools. The method is target specific, but it is
4131expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]4132The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnere64d41d2005-11-15 06:07:55 +0000[diff] [blame]4133after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb40261e2006-03-24 07:16:10 +0000[diff] [blame]4134optimizations. The intended use is to be inserted after optimizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4135correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4136</p>
4137
4138<h5>Arguments:</h5>
4139
4140<p>
4141<tt>id</tt> is a numerical id identifying the marker.
4142</p>
4143
4144<h5>Semantics:</h5>
4145
4146<p>
4147This intrinsic does not modify the behavior of the program. Backends that do not
4148support this intrinisic may ignore it.
4149</p>
4150
4151</div>
4152
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4153<!-- _______________________________________________________________________ -->
4154<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4155 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4156</div>
4157
4158<div class="doc_text">
4159
4160<h5>Syntax:</h5>
4161<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4162 declare i64 @llvm.readcyclecounter( )
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4163</pre>
4164
4165<h5>Overview:</h5>
4166
4167
4168<p>
4169The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4170counter register (or similar low latency, high accuracy clocks) on those targets
4171that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4172As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4173should only be used for small timings.
4174</p>
4175
4176<h5>Semantics:</h5>
4177
4178<p>
4179When directly supported, reading the cycle counter should not modify any memory.
4180Implementations are allowed to either return a application specific value or a
4181system wide value. On backends without support, this is lowered to a constant 0.
4182</p>
4183
4184</div>
4185
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4186<!-- ======================================================================= -->
4187<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4188 <a name="int_libc">Standard C Library Intrinsics</a>
4189</div>
4190
4191<div class="doc_text">
4192<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4193LLVM provides intrinsics for a few important standard C library functions.
4194These intrinsics allow source-language front-ends to pass information about the
4195alignment of the pointer arguments to the code generator, providing opportunity
4196for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4197</p>
4198
4199</div>
4200
4201<!-- _______________________________________________________________________ -->
4202<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4203 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4204</div>
4205
4206<div class="doc_text">
4207
4208<h5>Syntax:</h5>
4209<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4210 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4211 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4212 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4213 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4214</pre>
4215
4216<h5>Overview:</h5>
4217
4218<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4219The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4220location to the destination location.
4221</p>
4222
4223<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4224Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4225intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4226</p>
4227
4228<h5>Arguments:</h5>
4229
4230<p>
4231The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4232the source. The third argument is an integer argument
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4233specifying the number of bytes to copy, and the fourth argument is the alignment
4234of the source and destination locations.
4235</p>
4236
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4237<p>
4238If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattner5316e5d2006-03-04 00:02:10 +0000[diff] [blame]4239the caller guarantees that both the source and destination pointers are aligned
4240to that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4241</p>
4242
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4243<h5>Semantics:</h5>
4244
4245<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4246The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4247location to the destination location, which are not allowed to overlap. It
4248copies "len" bytes of memory over. If the argument is known to be aligned to
4249some boundary, this can be specified as the fourth argument, otherwise it should
4250be set to 0 or 1.
4251</p>
4252</div>
4253
4254
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4255<!-- _______________________________________________________________________ -->
4256<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4257 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4258</div>
4259
4260<div class="doc_text">
4261
4262<h5>Syntax:</h5>
4263<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4264 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4265 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4266 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4267 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4268</pre>
4269
4270<h5>Overview:</h5>
4271
4272<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4273The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4274location to the destination location. It is similar to the
4275'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4276</p>
4277
4278<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4279Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4280intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4281</p>
4282
4283<h5>Arguments:</h5>
4284
4285<p>
4286The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4287the source. The third argument is an integer argument
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4288specifying the number of bytes to copy, and the fourth argument is the alignment
4289of the source and destination locations.
4290</p>
4291
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4292<p>
4293If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattner5316e5d2006-03-04 00:02:10 +0000[diff] [blame]4294the caller guarantees that the source and destination pointers are aligned to
4295that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4296</p>
4297
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4298<h5>Semantics:</h5>
4299
4300<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4301The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4302location to the destination location, which may overlap. It
4303copies "len" bytes of memory over. If the argument is known to be aligned to
4304some boundary, this can be specified as the fourth argument, otherwise it should
4305be set to 0 or 1.
4306</p>
4307</div>
4308
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4309
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4310<!-- _______________________________________________________________________ -->
4311<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4312 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4313</div>
4314
4315<div class="doc_text">
4316
4317<h5>Syntax:</h5>
4318<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4319 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4320 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4321 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4322 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4323</pre>
4324
4325<h5>Overview:</h5>
4326
4327<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4328The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4329byte value.
4330</p>
4331
4332<p>
4333Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4334does not return a value, and takes an extra alignment argument.
4335</p>
4336
4337<h5>Arguments:</h5>
4338
4339<p>
4340The first argument is a pointer to the destination to fill, the second is the
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4341byte value to fill it with, the third argument is an integer
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4342argument specifying the number of bytes to fill, and the fourth argument is the
4343known alignment of destination location.
4344</p>
4345
4346<p>
4347If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattner5316e5d2006-03-04 00:02:10 +0000[diff] [blame]4348the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4349</p>
4350
4351<h5>Semantics:</h5>
4352
4353<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4354The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4355the
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4356destination location. If the argument is known to be aligned to some boundary,
4357this can be specified as the fourth argument, otherwise it should be set to 0 or
43581.
4359</p>
4360</div>
4361
4362
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4363<!-- _______________________________________________________________________ -->
4364<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4365 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4366</div>
4367
4368<div class="doc_text">
4369
4370<h5>Syntax:</h5>
4371<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4372 declare float @llvm.sqrt.f32(float %Val)
4373 declare double @llvm.sqrt.f64(double %Val)
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4374</pre>
4375
4376<h5>Overview:</h5>
4377
4378<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4379The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4380returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4381<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4382negative numbers (which allows for better optimization).
4383</p>
4384
4385<h5>Arguments:</h5>
4386
4387<p>
4388The argument and return value are floating point numbers of the same type.
4389</p>
4390
4391<h5>Semantics:</h5>
4392
4393<p>
4394This function returns the sqrt of the specified operand if it is a positive
4395floating point number.
4396</p>
4397</div>
4398
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4399<!-- _______________________________________________________________________ -->
4400<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4401 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4402</div>
4403
4404<div class="doc_text">
4405
4406<h5>Syntax:</h5>
4407<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4408 declare float @llvm.powi.f32(float %Val, i32 %power)
4409 declare double @llvm.powi.f64(double %Val, i32 %power)
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4410</pre>
4411
4412<h5>Overview:</h5>
4413
4414<p>
4415The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4416specified (positive or negative) power. The order of evaluation of
4417multiplications is not defined.
4418</p>
4419
4420<h5>Arguments:</h5>
4421
4422<p>
4423The second argument is an integer power, and the first is a value to raise to
4424that power.
4425</p>
4426
4427<h5>Semantics:</h5>
4428
4429<p>
4430This function returns the first value raised to the second power with an
4431unspecified sequence of rounding operations.</p>
4432</div>
4433
4434
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4435<!-- ======================================================================= -->
4436<div class="doc_subsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4437 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4438</div>
4439
4440<div class="doc_text">
4441<p>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4442LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4443These allow efficient code generation for some algorithms.
4444</p>
4445
4446</div>
4447
4448<!-- _______________________________________________________________________ -->
4449<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4450 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4451</div>
4452
4453<div class="doc_text">
4454
4455<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4456<p>This is an overloaded intrinsic function. You can use bswap on any integer
4457type that is an even number of bytes (i.e. BitWidth % 16 == 0). Note the suffix
4458that includes the type for the result and the operand.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4459<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4460 declare i16 @llvm.bswap.i16.i16(i16 &lt;id&gt;)
4461 declare i32 @llvm.bswap.i32.i32(i32 &lt;id&gt;)
Reid Spencer403a1c42007-04-02 00:19:52 +0000[diff] [blame]4462 declare i64 @llvm.bswap.i64.i64(i64 &lt;id&gt;)
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4463</pre>
4464
4465<h5>Overview:</h5>
4466
4467<p>
Reid Spencerf361c4f2007-04-02 02:25:19 +0000[diff] [blame]4468The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4469values with an even number of bytes (positive multiple of 16 bits). These are
4470useful for performing operations on data that is not in the target's native
4471byte order.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4472</p>
4473
4474<h5>Semantics:</h5>
4475
4476<p>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4477The <tt>llvm.bswap.16.i16</tt> intrinsic returns an i16 value that has the high
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4478and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4479intrinsic returns an i32 value that has the four bytes of the input i32
4480swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4481i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48.i48</tt>,
4482<tt>llvm.bswap.i64.i64</tt> and other intrinsics extend this concept to
4483additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4484</p>
4485
4486</div>
4487
4488<!-- _______________________________________________________________________ -->
4489<div class="doc_subsubsection">
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4490 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4491</div>
4492
4493<div class="doc_text">
4494
4495<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4496<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4497width. Not all targets support all bit widths however.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4498<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4499 declare i32 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4500 declare i32 @llvm.ctpop.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4501 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4502 declare i32 @llvm.ctpop.i64(i64 &lt;src&gt;)
4503 declare i32 @llvm.ctpop.i256(i256 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4504</pre>
4505
4506<h5>Overview:</h5>
4507
4508<p>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]4509The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4510value.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4511</p>
4512
4513<h5>Arguments:</h5>
4514
4515<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4516The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4517integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4518</p>
4519
4520<h5>Semantics:</h5>
4521
4522<p>
4523The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4524</p>
4525</div>
4526
4527<!-- _______________________________________________________________________ -->
4528<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4529 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4530</div>
4531
4532<div class="doc_text">
4533
4534<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4535<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4536integer bit width. Not all targets support all bit widths however.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4537<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4538 declare i32 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4539 declare i32 @llvm.ctlz.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4540 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4541 declare i32 @llvm.ctlz.i64(i64 &lt;src&gt;)
4542 declare i32 @llvm.ctlz.i256(i256 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4543</pre>
4544
4545<h5>Overview:</h5>
4546
4547<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4548The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4549leading zeros in a variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4550</p>
4551
4552<h5>Arguments:</h5>
4553
4554<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4555The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4556integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4557</p>
4558
4559<h5>Semantics:</h5>
4560
4561<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4562The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4563in a variable. If the src == 0 then the result is the size in bits of the type
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4564of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4565</p>
4566</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4567
4568
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4569
4570<!-- _______________________________________________________________________ -->
4571<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4572 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4573</div>
4574
4575<div class="doc_text">
4576
4577<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4578<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4579integer bit width. Not all targets support all bit widths however.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4580<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4581 declare i32 @llvm.cttz.i8 (i8 &lt;src&gt;)
4582 declare i32 @llvm.cttz.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4583 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4584 declare i32 @llvm.cttz.i64(i64 &lt;src&gt;)
4585 declare i32 @llvm.cttz.i256(i256 &lt;src&gt;)
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4586</pre>
4587
4588<h5>Overview:</h5>
4589
4590<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4591The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4592trailing zeros.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4593</p>
4594
4595<h5>Arguments:</h5>
4596
4597<p>
4598The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4599integer type. The return type must match the argument type.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4600</p>
4601
4602<h5>Semantics:</h5>
4603
4604<p>
4605The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4606in a variable. If the src == 0 then the result is the size in bits of the type
4607of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4608</p>
4609</div>
4610
Reid Spencer8a5799f2007-04-01 08:27:01 +0000[diff] [blame]4611<!-- _______________________________________________________________________ -->
4612<div class="doc_subsubsection">
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4613 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4614</div>
4615
4616<div class="doc_text">
4617
4618<h5>Syntax:</h5>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4619<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4620on any integer bit width.
4621<pre>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4622 declare i17 @llvm.part.select.i17.i17 (i17 %val, i32 %loBit, i32 %hiBit)
4623 declare i29 @llvm.part.select.i29.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4624</pre>
4625
4626<h5>Overview:</h5>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4627<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4628range of bits from an integer value and returns them in the same bit width as
4629the original value.</p>
4630
4631<h5>Arguments:</h5>
4632<p>The first argument, <tt>%val</tt> and the result may be integer types of
4633any bit width but they must have the same bit width. The second and third
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4634arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4635
4636<h5>Semantics:</h5>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4637<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4638of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
4639<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
4640operates in forward mode.</p>
4641<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
4642right by <tt>%loBit</tt> bits and then ANDing it with a mask with
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4643only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
4644<ol>
4645 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
4646 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
4647 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
4648 to determine the number of bits to retain.</li>
4649 <li>A mask of the retained bits is created by shifting a -1 value.</li>
4650 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
4651</ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4652<p>In reverse mode, a similar computation is made except that:</p>
4653<ol>
4654 <li>The bits selected wrap around to include both the highest and lowest bits.
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4655 For example, part.select(i16 X, 4, 7) selects bits from X with a mask of
4656 0x00F0 (forwards case) while part.select(i16 X, 8, 3) selects bits from X
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4657 with a mask of 0xFF0F.</li>
4658 <li>The bits returned in the reverse case are reversed. So, if X has the value
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4659 0x6ACF and we apply part.select(i16 X, 8, 3) to it, we get back the value
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4660 0x0A6F.</li>
4661</ol>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4662</div>
4663
Reid Spencer5bf54c82007-04-11 23:23:49 +0000[diff] [blame]4664<div class="doc_subsubsection">
4665 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
4666</div>
4667
4668<div class="doc_text">
4669
4670<h5>Syntax:</h5>
4671<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
4672on any integer bit width.
4673<pre>
4674 declare i17 @llvm.part.set.i17.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
4675 declare i29 @llvm.part.set.i29.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
4676</pre>
4677
4678<h5>Overview:</h5>
4679<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
4680of bits in an integer value with another integer value. It returns the integer
4681with the replaced bits.</p>
4682
4683<h5>Arguments:</h5>
4684<p>The first argument, <tt>%val</tt> and the result may be integer types of
4685any bit width but they must have the same bit width. <tt>%val</tt> is the value
4686whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
4687integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
4688type since they specify only a bit index.</p>
4689
4690<h5>Semantics:</h5>
4691<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
4692of operation: forwards and reverse. If <tt>%lo</tt> is greater than
4693<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
4694operates in forward mode.</p>
4695<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
4696truncating it down to the size of the replacement area or zero extending it
4697up to that size.</p>
4698<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
4699are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
4700in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
4701to the <tt>%hi</tt>th bit.
4702<p>In reverse mode, a similar computation is made except that the bits replaced
4703wrap around to include both the highest and lowest bits. For example, if a
470416 bit value is being replaced then <tt>%lo=8</tt> and <tt>%hi=4</tt> would
Reid Spencer14194dc2007-04-11 23:46:06 +0000[diff] [blame]4705cause these bits to be set: <tt>0xFF1F</tt>.</p>
Reid Spencer5bf54c82007-04-11 23:23:49 +0000[diff] [blame]4706<h5>Examples:</h5>
4707<pre>
Reid Spencerc70afc32007-04-12 01:03:03 +0000[diff] [blame]4708 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
4709 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0x0060
4710 llvm.part.set(0xFFFF, 0, 8, 3) -&gt; 0x00F0
4711 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
Reid Spencer7972c472007-04-11 23:49:50 +0000[diff] [blame]4712</pre>
Reid Spencer5bf54c82007-04-11 23:23:49 +0000[diff] [blame]4713</div>
4714
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4715<!-- ======================================================================= -->
4716<div class="doc_subsection">
4717 <a name="int_debugger">Debugger Intrinsics</a>
4718</div>
4719
4720<div class="doc_text">
4721<p>
4722The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4723are described in the <a
4724href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4725Debugging</a> document.
4726</p>
4727</div>
4728
4729
Jim Laskey2211f492007-03-14 19:31:19 +0000[diff] [blame]4730<!-- ======================================================================= -->
4731<div class="doc_subsection">
4732 <a name="int_eh">Exception Handling Intrinsics</a>
4733</div>
4734
4735<div class="doc_text">
4736<p> The LLVM exception handling intrinsics (which all start with
4737<tt>llvm.eh.</tt> prefix), are described in the <a
4738href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
4739Handling</a> document. </p>
4740</div>
4741
4742
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4743<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4744<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4745<address>
4746 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4747 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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4749 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4750
4751 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +0000[diff] [blame]4752 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4753 Last modified: $Date$
4754</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]4755</body>
4756</html>