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5 <title>LLVM Assembly Language Reference Manual</title>
6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
12
13<body>
14
15<div class="doc_title"> LLVM Language Reference Manual </div>
16<ol>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
23 <li><a href="#linkage">Linkage Types</a></li>
24 <li><a href="#callingconv">Calling Conventions</a></li>
25 <li><a href="#globalvars">Global Variables</a></li>
26 <li><a href="#functionstructure">Functions</a></li>
27 <li><a href="#aliasstructure">Aliases</a>
28 <li><a href="#paramattrs">Parameter Attributes</a></li>
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]29 <li><a href="#gc">Garbage Collector Names</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]30 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
31 <li><a href="#datalayout">Data Layout</a></li>
32 </ol>
33 </li>
34 <li><a href="#typesystem">Type System</a>
35 <ol>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]36 <li><a href="#t_classifications">Type Classifications</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]37 <li><a href="#t_primitive">Primitive Types</a>
38 <ol>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]39 <li><a href="#t_floating">Floating Point Types</a></li>
40 <li><a href="#t_void">Void Type</a></li>
41 <li><a href="#t_label">Label Type</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]42 </ol>
43 </li>
44 <li><a href="#t_derived">Derived Types</a>
45 <ol>
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]46 <li><a href="#t_integer">Integer Type</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]47 <li><a href="#t_array">Array Type</a></li>
48 <li><a href="#t_function">Function Type</a></li>
49 <li><a href="#t_pointer">Pointer Type</a></li>
50 <li><a href="#t_struct">Structure Type</a></li>
51 <li><a href="#t_pstruct">Packed Structure Type</a></li>
52 <li><a href="#t_vector">Vector Type</a></li>
53 <li><a href="#t_opaque">Opaque Type</a></li>
54 </ol>
55 </li>
56 </ol>
57 </li>
58 <li><a href="#constants">Constants</a>
59 <ol>
60 <li><a href="#simpleconstants">Simple Constants</a>
61 <li><a href="#aggregateconstants">Aggregate Constants</a>
62 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
63 <li><a href="#undefvalues">Undefined Values</a>
64 <li><a href="#constantexprs">Constant Expressions</a>
65 </ol>
66 </li>
67 <li><a href="#othervalues">Other Values</a>
68 <ol>
69 <li><a href="#inlineasm">Inline Assembler Expressions</a>
70 </ol>
71 </li>
72 <li><a href="#instref">Instruction Reference</a>
73 <ol>
74 <li><a href="#terminators">Terminator Instructions</a>
75 <ol>
76 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
77 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
78 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
79 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
80 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
81 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
82 </ol>
83 </li>
84 <li><a href="#binaryops">Binary Operations</a>
85 <ol>
86 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
87 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
88 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
89 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
90 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
91 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
92 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
93 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
94 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
95 </ol>
96 </li>
97 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
98 <ol>
99 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
100 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
101 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
102 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
103 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
104 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
105 </ol>
106 </li>
107 <li><a href="#vectorops">Vector Operations</a>
108 <ol>
109 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
110 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
111 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
112 </ol>
113 </li>
114 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
115 <ol>
116 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
117 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
118 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
119 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
120 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
121 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
122 </ol>
123 </li>
124 <li><a href="#convertops">Conversion Operations</a>
125 <ol>
126 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
127 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
128 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
129 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
130 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
131 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
132 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
133 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
134 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
135 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
136 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
137 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
138 </ol>
139 <li><a href="#otherops">Other Operations</a>
140 <ol>
141 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
142 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
143 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
144 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
145 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
146 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]147 <li><a href="#i_getresult">'<tt>getresult</tt>' Instruction</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]148 </ol>
149 </li>
150 </ol>
151 </li>
152 <li><a href="#intrinsics">Intrinsic Functions</a>
153 <ol>
154 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
155 <ol>
156 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
157 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
158 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
159 </ol>
160 </li>
161 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
162 <ol>
163 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
164 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
165 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
166 </ol>
167 </li>
168 <li><a href="#int_codegen">Code Generator Intrinsics</a>
169 <ol>
170 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
171 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
172 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
173 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
174 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
175 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
176 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
177 </ol>
178 </li>
179 <li><a href="#int_libc">Standard C Library Intrinsics</a>
180 <ol>
181 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
182 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
183 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
184 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
185 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]186 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
187 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
188 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]189 </ol>
190 </li>
191 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
192 <ol>
193 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
194 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
195 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
196 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
197 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
198 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
199 </ol>
200 </li>
201 <li><a href="#int_debugger">Debugger intrinsics</a></li>
202 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]203 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]204 <ol>
205 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]206 </ol>
207 </li>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]208 <li><a href="#int_atomics">Atomic intrinsics</a>
209 <ol>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]210 <li><a href="#int_memory_barrier"><tt>llvm.memory_barrier</tt></a></li>
211 <li><a href="#int_atomic_lcs"><tt>llvm.atomic.lcs</tt></a></li>
212 <li><a href="#int_atomic_las"><tt>llvm.atomic.las</tt></a></li>
213 <li><a href="#int_atomic_swap"><tt>llvm.atomic.swap</tt></a></li>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]214 </ol>
215 </li>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]216 <li><a href="#int_general">General intrinsics</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]217 <ol>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]218 <li><a href="#int_var_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]219 <tt>llvm.var.annotation</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]220 <li><a href="#int_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]221 <tt>llvm.annotation.*</tt>' Intrinsic</a></li>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]222 <li><a href="#int_trap">
223 <tt>llvm.trap</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]224 </ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]225 </li>
226 </ol>
227 </li>
228</ol>
229
230<div class="doc_author">
231 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
232 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
233</div>
234
235<!-- *********************************************************************** -->
236<div class="doc_section"> <a name="abstract">Abstract </a></div>
237<!-- *********************************************************************** -->
238
239<div class="doc_text">
240<p>This document is a reference manual for the LLVM assembly language.
241LLVM is an SSA based representation that provides type safety,
242low-level operations, flexibility, and the capability of representing
243'all' high-level languages cleanly. It is the common code
244representation used throughout all phases of the LLVM compilation
245strategy.</p>
246</div>
247
248<!-- *********************************************************************** -->
249<div class="doc_section"> <a name="introduction">Introduction</a> </div>
250<!-- *********************************************************************** -->
251
252<div class="doc_text">
253
254<p>The LLVM code representation is designed to be used in three
255different forms: as an in-memory compiler IR, as an on-disk bitcode
256representation (suitable for fast loading by a Just-In-Time compiler),
257and as a human readable assembly language representation. This allows
258LLVM to provide a powerful intermediate representation for efficient
259compiler transformations and analysis, while providing a natural means
260to debug and visualize the transformations. The three different forms
261of LLVM are all equivalent. This document describes the human readable
262representation and notation.</p>
263
264<p>The LLVM representation aims to be light-weight and low-level
265while being expressive, typed, and extensible at the same time. It
266aims to be a "universal IR" of sorts, by being at a low enough level
267that high-level ideas may be cleanly mapped to it (similar to how
268microprocessors are "universal IR's", allowing many source languages to
269be mapped to them). By providing type information, LLVM can be used as
270the target of optimizations: for example, through pointer analysis, it
271can be proven that a C automatic variable is never accessed outside of
272the current function... allowing it to be promoted to a simple SSA
273value instead of a memory location.</p>
274
275</div>
276
277<!-- _______________________________________________________________________ -->
278<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
279
280<div class="doc_text">
281
282<p>It is important to note that this document describes 'well formed'
283LLVM assembly language. There is a difference between what the parser
284accepts and what is considered 'well formed'. For example, the
285following instruction is syntactically okay, but not well formed:</p>
286
287<div class="doc_code">
288<pre>
289%x = <a href="#i_add">add</a> i32 1, %x
290</pre>
291</div>
292
293<p>...because the definition of <tt>%x</tt> does not dominate all of
294its uses. The LLVM infrastructure provides a verification pass that may
295be used to verify that an LLVM module is well formed. This pass is
296automatically run by the parser after parsing input assembly and by
297the optimizer before it outputs bitcode. The violations pointed out
298by the verifier pass indicate bugs in transformation passes or input to
299the parser.</p>
300</div>
301
Chris Lattnera83fdc02007-10-03 17:34:29 +0000[diff] [blame]302<!-- Describe the typesetting conventions here. -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]303
304<!-- *********************************************************************** -->
305<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
306<!-- *********************************************************************** -->
307
308<div class="doc_text">
309
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]310 <p>LLVM identifiers come in two basic types: global and local. Global
311 identifiers (functions, global variables) begin with the @ character. Local
312 identifiers (register names, types) begin with the % character. Additionally,
313 there are three different formats for identifiers, for different purposes:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]314
315<ol>
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]316 <li>Named values are represented as a string of characters with their prefix.
317 For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
318 regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]319 Identifiers which require other characters in their names can be surrounded
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]320 with quotes. In this way, anything except a <tt>&quot;</tt> character can
321 be used in a named value.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]322
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]323 <li>Unnamed values are represented as an unsigned numeric value with their
324 prefix. For example, %12, @2, %44.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]325
326 <li>Constants, which are described in a <a href="#constants">section about
327 constants</a>, below.</li>
328</ol>
329
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]330<p>LLVM requires that values start with a prefix for two reasons: Compilers
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]331don't need to worry about name clashes with reserved words, and the set of
332reserved words may be expanded in the future without penalty. Additionally,
333unnamed identifiers allow a compiler to quickly come up with a temporary
334variable without having to avoid symbol table conflicts.</p>
335
336<p>Reserved words in LLVM are very similar to reserved words in other
337languages. There are keywords for different opcodes
338('<tt><a href="#i_add">add</a></tt>',
339 '<tt><a href="#i_bitcast">bitcast</a></tt>',
340 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
341href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
342and others. These reserved words cannot conflict with variable names, because
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]343none of them start with a prefix character ('%' or '@').</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]344
345<p>Here is an example of LLVM code to multiply the integer variable
346'<tt>%X</tt>' by 8:</p>
347
348<p>The easy way:</p>
349
350<div class="doc_code">
351<pre>
352%result = <a href="#i_mul">mul</a> i32 %X, 8
353</pre>
354</div>
355
356<p>After strength reduction:</p>
357
358<div class="doc_code">
359<pre>
360%result = <a href="#i_shl">shl</a> i32 %X, i8 3
361</pre>
362</div>
363
364<p>And the hard way:</p>
365
366<div class="doc_code">
367<pre>
368<a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
369<a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
370%result = <a href="#i_add">add</a> i32 %1, %1
371</pre>
372</div>
373
374<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
375important lexical features of LLVM:</p>
376
377<ol>
378
379 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
380 line.</li>
381
382 <li>Unnamed temporaries are created when the result of a computation is not
383 assigned to a named value.</li>
384
385 <li>Unnamed temporaries are numbered sequentially</li>
386
387</ol>
388
389<p>...and it also shows a convention that we follow in this document. When
390demonstrating instructions, we will follow an instruction with a comment that
391defines the type and name of value produced. Comments are shown in italic
392text.</p>
393
394</div>
395
396<!-- *********************************************************************** -->
397<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
398<!-- *********************************************************************** -->
399
400<!-- ======================================================================= -->
401<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
402</div>
403
404<div class="doc_text">
405
406<p>LLVM programs are composed of "Module"s, each of which is a
407translation unit of the input programs. Each module consists of
408functions, global variables, and symbol table entries. Modules may be
409combined together with the LLVM linker, which merges function (and
410global variable) definitions, resolves forward declarations, and merges
411symbol table entries. Here is an example of the "hello world" module:</p>
412
413<div class="doc_code">
414<pre><i>; Declare the string constant as a global constant...</i>
415<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
416 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
417
418<i>; External declaration of the puts function</i>
419<a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
420
421<i>; Definition of main function</i>
422define i32 @main() { <i>; i32()* </i>
423 <i>; Convert [13x i8 ]* to i8 *...</i>
424 %cast210 = <a
425 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
426
427 <i>; Call puts function to write out the string to stdout...</i>
428 <a
429 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
430 <a
431 href="#i_ret">ret</a> i32 0<br>}<br>
432</pre>
433</div>
434
435<p>This example is made up of a <a href="#globalvars">global variable</a>
436named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
437function, and a <a href="#functionstructure">function definition</a>
438for "<tt>main</tt>".</p>
439
440<p>In general, a module is made up of a list of global values,
441where both functions and global variables are global values. Global values are
442represented by a pointer to a memory location (in this case, a pointer to an
443array of char, and a pointer to a function), and have one of the following <a
444href="#linkage">linkage types</a>.</p>
445
446</div>
447
448<!-- ======================================================================= -->
449<div class="doc_subsection">
450 <a name="linkage">Linkage Types</a>
451</div>
452
453<div class="doc_text">
454
455<p>
456All Global Variables and Functions have one of the following types of linkage:
457</p>
458
459<dl>
460
461 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
462
463 <dd>Global values with internal linkage are only directly accessible by
464 objects in the current module. In particular, linking code into a module with
465 an internal global value may cause the internal to be renamed as necessary to
466 avoid collisions. Because the symbol is internal to the module, all
467 references can be updated. This corresponds to the notion of the
468 '<tt>static</tt>' keyword in C.
469 </dd>
470
471 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
472
473 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
474 the same name when linkage occurs. This is typically used to implement
475 inline functions, templates, or other code which must be generated in each
476 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
477 allowed to be discarded.
478 </dd>
479
480 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
481
482 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
483 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
484 used for globals that may be emitted in multiple translation units, but that
485 are not guaranteed to be emitted into every translation unit that uses them.
486 One example of this are common globals in C, such as "<tt>int X;</tt>" at
487 global scope.
488 </dd>
489
490 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
491
492 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
493 pointer to array type. When two global variables with appending linkage are
494 linked together, the two global arrays are appended together. This is the
495 LLVM, typesafe, equivalent of having the system linker append together
496 "sections" with identical names when .o files are linked.
497 </dd>
498
499 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
500 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
501 until linked, if not linked, the symbol becomes null instead of being an
502 undefined reference.
503 </dd>
504
505 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
506
507 <dd>If none of the above identifiers are used, the global is externally
508 visible, meaning that it participates in linkage and can be used to resolve
509 external symbol references.
510 </dd>
511</dl>
512
513 <p>
514 The next two types of linkage are targeted for Microsoft Windows platform
515 only. They are designed to support importing (exporting) symbols from (to)
516 DLLs.
517 </p>
518
519 <dl>
520 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
521
522 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
523 or variable via a global pointer to a pointer that is set up by the DLL
524 exporting the symbol. On Microsoft Windows targets, the pointer name is
525 formed by combining <code>_imp__</code> and the function or variable name.
526 </dd>
527
528 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
529
530 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
531 pointer to a pointer in a DLL, so that it can be referenced with the
532 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
533 name is formed by combining <code>_imp__</code> and the function or variable
534 name.
535 </dd>
536
537</dl>
538
539<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
540variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
541variable and was linked with this one, one of the two would be renamed,
542preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
543external (i.e., lacking any linkage declarations), they are accessible
544outside of the current module.</p>
545<p>It is illegal for a function <i>declaration</i>
546to have any linkage type other than "externally visible", <tt>dllimport</tt>,
547or <tt>extern_weak</tt>.</p>
548<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
549linkages.
550</div>
551
552<!-- ======================================================================= -->
553<div class="doc_subsection">
554 <a name="callingconv">Calling Conventions</a>
555</div>
556
557<div class="doc_text">
558
559<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
560and <a href="#i_invoke">invokes</a> can all have an optional calling convention
561specified for the call. The calling convention of any pair of dynamic
562caller/callee must match, or the behavior of the program is undefined. The
563following calling conventions are supported by LLVM, and more may be added in
564the future:</p>
565
566<dl>
567 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
568
569 <dd>This calling convention (the default if no other calling convention is
570 specified) matches the target C calling conventions. This calling convention
571 supports varargs function calls and tolerates some mismatch in the declared
572 prototype and implemented declaration of the function (as does normal C).
573 </dd>
574
575 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
576
577 <dd>This calling convention attempts to make calls as fast as possible
578 (e.g. by passing things in registers). This calling convention allows the
579 target to use whatever tricks it wants to produce fast code for the target,
580 without having to conform to an externally specified ABI. Implementations of
581 this convention should allow arbitrary tail call optimization to be supported.
582 This calling convention does not support varargs and requires the prototype of
583 all callees to exactly match the prototype of the function definition.
584 </dd>
585
586 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
587
588 <dd>This calling convention attempts to make code in the caller as efficient
589 as possible under the assumption that the call is not commonly executed. As
590 such, these calls often preserve all registers so that the call does not break
591 any live ranges in the caller side. This calling convention does not support
592 varargs and requires the prototype of all callees to exactly match the
593 prototype of the function definition.
594 </dd>
595
596 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
597
598 <dd>Any calling convention may be specified by number, allowing
599 target-specific calling conventions to be used. Target specific calling
600 conventions start at 64.
601 </dd>
602</dl>
603
604<p>More calling conventions can be added/defined on an as-needed basis, to
605support pascal conventions or any other well-known target-independent
606convention.</p>
607
608</div>
609
610<!-- ======================================================================= -->
611<div class="doc_subsection">
612 <a name="visibility">Visibility Styles</a>
613</div>
614
615<div class="doc_text">
616
617<p>
618All Global Variables and Functions have one of the following visibility styles:
619</p>
620
621<dl>
622 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
623
624 <dd>On ELF, default visibility means that the declaration is visible to other
625 modules and, in shared libraries, means that the declared entity may be
626 overridden. On Darwin, default visibility means that the declaration is
627 visible to other modules. Default visibility corresponds to "external
628 linkage" in the language.
629 </dd>
630
631 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
632
633 <dd>Two declarations of an object with hidden visibility refer to the same
634 object if they are in the same shared object. Usually, hidden visibility
635 indicates that the symbol will not be placed into the dynamic symbol table,
636 so no other module (executable or shared library) can reference it
637 directly.
638 </dd>
639
640 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
641
642 <dd>On ELF, protected visibility indicates that the symbol will be placed in
643 the dynamic symbol table, but that references within the defining module will
644 bind to the local symbol. That is, the symbol cannot be overridden by another
645 module.
646 </dd>
647</dl>
648
649</div>
650
651<!-- ======================================================================= -->
652<div class="doc_subsection">
653 <a name="globalvars">Global Variables</a>
654</div>
655
656<div class="doc_text">
657
658<p>Global variables define regions of memory allocated at compilation time
659instead of run-time. Global variables may optionally be initialized, may have
660an explicit section to be placed in, and may have an optional explicit alignment
661specified. A variable may be defined as "thread_local", which means that it
662will not be shared by threads (each thread will have a separated copy of the
663variable). A variable may be defined as a global "constant," which indicates
664that the contents of the variable will <b>never</b> be modified (enabling better
665optimization, allowing the global data to be placed in the read-only section of
666an executable, etc). Note that variables that need runtime initialization
667cannot be marked "constant" as there is a store to the variable.</p>
668
669<p>
670LLVM explicitly allows <em>declarations</em> of global variables to be marked
671constant, even if the final definition of the global is not. This capability
672can be used to enable slightly better optimization of the program, but requires
673the language definition to guarantee that optimizations based on the
674'constantness' are valid for the translation units that do not include the
675definition.
676</p>
677
678<p>As SSA values, global variables define pointer values that are in
679scope (i.e. they dominate) all basic blocks in the program. Global
680variables always define a pointer to their "content" type because they
681describe a region of memory, and all memory objects in LLVM are
682accessed through pointers.</p>
683
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]684<p>A global variable may be declared to reside in a target-specifc numbered
685address space. For targets that support them, address spaces may affect how
686optimizations are performed and/or what target instructions are used to access
Christopher Lamb20a39e92007-12-12 08:44:39 +0000[diff] [blame]687the variable. The default address space is zero. The address space qualifier
688must precede any other attributes.</p>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]689
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]690<p>LLVM allows an explicit section to be specified for globals. If the target
691supports it, it will emit globals to the section specified.</p>
692
693<p>An explicit alignment may be specified for a global. If not present, or if
694the alignment is set to zero, the alignment of the global is set by the target
695to whatever it feels convenient. If an explicit alignment is specified, the
696global is forced to have at least that much alignment. All alignments must be
697a power of 2.</p>
698
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]699<p>For example, the following defines a global in a numbered address space with
700an initializer, section, and alignment:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]701
702<div class="doc_code">
703<pre>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]704@G = constant float 1.0 addrspace(5), section "foo", align 4
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]705</pre>
706</div>
707
708</div>
709
710
711<!-- ======================================================================= -->
712<div class="doc_subsection">
713 <a name="functionstructure">Functions</a>
714</div>
715
716<div class="doc_text">
717
718<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
719an optional <a href="#linkage">linkage type</a>, an optional
720<a href="#visibility">visibility style</a>, an optional
721<a href="#callingconv">calling convention</a>, a return type, an optional
722<a href="#paramattrs">parameter attribute</a> for the return type, a function
723name, a (possibly empty) argument list (each with optional
724<a href="#paramattrs">parameter attributes</a>), an optional section, an
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]725optional alignment, an optional <a href="#gc">garbage collector name</a>, an
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]726opening curly brace, a list of basic blocks, and a closing curly brace.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]727
728LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
729optional <a href="#linkage">linkage type</a>, an optional
730<a href="#visibility">visibility style</a>, an optional
731<a href="#callingconv">calling convention</a>, a return type, an optional
732<a href="#paramattrs">parameter attribute</a> for the return type, a function
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]733name, a possibly empty list of arguments, an optional alignment, and an optional
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]734<a href="#gc">garbage collector name</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]735
736<p>A function definition contains a list of basic blocks, forming the CFG for
737the function. Each basic block may optionally start with a label (giving the
738basic block a symbol table entry), contains a list of instructions, and ends
739with a <a href="#terminators">terminator</a> instruction (such as a branch or
740function return).</p>
741
742<p>The first basic block in a function is special in two ways: it is immediately
743executed on entrance to the function, and it is not allowed to have predecessor
744basic blocks (i.e. there can not be any branches to the entry block of a
745function). Because the block can have no predecessors, it also cannot have any
746<a href="#i_phi">PHI nodes</a>.</p>
747
748<p>LLVM allows an explicit section to be specified for functions. If the target
749supports it, it will emit functions to the section specified.</p>
750
751<p>An explicit alignment may be specified for a function. If not present, or if
752the alignment is set to zero, the alignment of the function is set by the target
753to whatever it feels convenient. If an explicit alignment is specified, the
754function is forced to have at least that much alignment. All alignments must be
755a power of 2.</p>
756
757</div>
758
759
760<!-- ======================================================================= -->
761<div class="doc_subsection">
762 <a name="aliasstructure">Aliases</a>
763</div>
764<div class="doc_text">
765 <p>Aliases act as "second name" for the aliasee value (which can be either
Anton Korobeynikov96822812008-03-22 08:36:14 +0000[diff] [blame]766 function, global variable, another alias or bitcast of global value). Aliases
767 may have an optional <a href="#linkage">linkage type</a>, and an
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]768 optional <a href="#visibility">visibility style</a>.</p>
769
770 <h5>Syntax:</h5>
771
772<div class="doc_code">
773<pre>
774@&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
775</pre>
776</div>
777
778</div>
779
780
781
782<!-- ======================================================================= -->
783<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
784<div class="doc_text">
785 <p>The return type and each parameter of a function type may have a set of
786 <i>parameter attributes</i> associated with them. Parameter attributes are
787 used to communicate additional information about the result or parameters of
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]788 a function. Parameter attributes are considered to be part of the function,
789 not of the function type, so functions with different parameter attributes
790 can have the same function type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]791
792 <p>Parameter attributes are simple keywords that follow the type specified. If
793 multiple parameter attributes are needed, they are space separated. For
794 example:</p>
795
796<div class="doc_code">
797<pre>
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]798declare i32 @printf(i8* noalias , ...) nounwind
799declare i32 @atoi(i8*) nounwind readonly
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]800</pre>
801</div>
802
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]803 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
804 <tt>readonly</tt>) come immediately after the argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]805
806 <p>Currently, only the following parameter attributes are defined:</p>
807 <dl>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]808 <dt><tt>zeroext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]809 <dd>This indicates that the parameter should be zero extended just before
810 a call to this function.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]811
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]812 <dt><tt>signext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]813 <dd>This indicates that the parameter should be sign extended just before
814 a call to this function.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]815
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]816 <dt><tt>inreg</tt></dt>
817 <dd>This indicates that the parameter should be placed in register (if
818 possible) during assembling function call. Support for this attribute is
819 target-specific</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]820
821 <dt><tt>byval</tt></dt>
Chris Lattner04c86182008-01-15 04:34:22 +0000[diff] [blame]822 <dd>This indicates that the pointer parameter should really be passed by
823 value to the function. The attribute implies that a hidden copy of the
824 pointee is made between the caller and the callee, so the callee is unable
825 to modify the value in the callee. This attribute is only valid on llvm
826 pointer arguments. It is generally used to pass structs and arrays by
827 value, but is also valid on scalars (even though this is silly).</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]828
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]829 <dt><tt>sret</tt></dt>
Duncan Sands616cc032008-02-18 04:19:38 +0000[diff] [blame]830 <dd>This indicates that the pointer parameter specifies the address of a
831 structure that is the return value of the function in the source program.
Duncan Sandsef0e9e42008-03-17 12:17:41 +0000[diff] [blame]832 Loads and stores to the structure are assumed not to trap.
Duncan Sands616cc032008-02-18 04:19:38 +0000[diff] [blame]833 May only be applied to the first parameter.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]834
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]835 <dt><tt>noalias</tt></dt>
Owen Andersonc4fc4cd2008-02-18 04:09:01 +0000[diff] [blame]836 <dd>This indicates that the parameter does not alias any global or any other
837 parameter. The caller is responsible for ensuring that this is the case,
838 usually by placing the value in a stack allocation.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]839
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]840 <dt><tt>noreturn</tt></dt>
841 <dd>This function attribute indicates that the function never returns. This
842 indicates to LLVM that every call to this function should be treated as if
843 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]844
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]845 <dt><tt>nounwind</tt></dt>
Duncan Sandsef0e9e42008-03-17 12:17:41 +0000[diff] [blame]846 <dd>This function attribute indicates that no exceptions unwind out of the
847 function. Usually this is because the function makes no use of exceptions,
848 but it may also be that the function catches any exceptions thrown when
849 executing it.</dd>
850
Duncan Sands4ee46812007-07-27 19:57:41 +0000[diff] [blame]851 <dt><tt>nest</tt></dt>
852 <dd>This indicates that the parameter can be excised using the
853 <a href="#int_trampoline">trampoline intrinsics</a>.</dd>
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]854 <dt><tt>readonly</tt></dt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]855 <dd>This function attribute indicates that the function has no side-effects
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]856 except for producing a return value or throwing an exception. The value
857 returned must only depend on the function arguments and/or global variables.
858 It may use values obtained by dereferencing pointers.</dd>
859 <dt><tt>readnone</tt></dt>
860 <dd>A <tt>readnone</tt> function has the same restrictions as a <tt>readonly</tt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]861 function, but in addition it is not allowed to dereference any pointer arguments
862 or global variables.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]863 </dl>
864
865</div>
866
867<!-- ======================================================================= -->
868<div class="doc_subsection">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]869 <a name="gc">Garbage Collector Names</a>
870</div>
871
872<div class="doc_text">
873<p>Each function may specify a garbage collector name, which is simply a
874string.</p>
875
876<div class="doc_code"><pre
877>define void @f() gc "name" { ...</pre></div>
878
879<p>The compiler declares the supported values of <i>name</i>. Specifying a
880collector which will cause the compiler to alter its output in order to support
881the named garbage collection algorithm.</p>
882</div>
883
884<!-- ======================================================================= -->
885<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]886 <a name="moduleasm">Module-Level Inline Assembly</a>
887</div>
888
889<div class="doc_text">
890<p>
891Modules may contain "module-level inline asm" blocks, which corresponds to the
892GCC "file scope inline asm" blocks. These blocks are internally concatenated by
893LLVM and treated as a single unit, but may be separated in the .ll file if
894desired. The syntax is very simple:
895</p>
896
897<div class="doc_code">
898<pre>
899module asm "inline asm code goes here"
900module asm "more can go here"
901</pre>
902</div>
903
904<p>The strings can contain any character by escaping non-printable characters.
905 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
906 for the number.
907</p>
908
909<p>
910 The inline asm code is simply printed to the machine code .s file when
911 assembly code is generated.
912</p>
913</div>
914
915<!-- ======================================================================= -->
916<div class="doc_subsection">
917 <a name="datalayout">Data Layout</a>
918</div>
919
920<div class="doc_text">
921<p>A module may specify a target specific data layout string that specifies how
922data is to be laid out in memory. The syntax for the data layout is simply:</p>
923<pre> target datalayout = "<i>layout specification</i>"</pre>
924<p>The <i>layout specification</i> consists of a list of specifications
925separated by the minus sign character ('-'). Each specification starts with a
926letter and may include other information after the letter to define some
927aspect of the data layout. The specifications accepted are as follows: </p>
928<dl>
929 <dt><tt>E</tt></dt>
930 <dd>Specifies that the target lays out data in big-endian form. That is, the
931 bits with the most significance have the lowest address location.</dd>
932 <dt><tt>e</tt></dt>
933 <dd>Specifies that hte target lays out data in little-endian form. That is,
934 the bits with the least significance have the lowest address location.</dd>
935 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
936 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
937 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
938 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
939 too.</dd>
940 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
941 <dd>This specifies the alignment for an integer type of a given bit
942 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
943 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
944 <dd>This specifies the alignment for a vector type of a given bit
945 <i>size</i>.</dd>
946 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
947 <dd>This specifies the alignment for a floating point type of a given bit
948 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
949 (double).</dd>
950 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
951 <dd>This specifies the alignment for an aggregate type of a given bit
952 <i>size</i>.</dd>
953</dl>
954<p>When constructing the data layout for a given target, LLVM starts with a
955default set of specifications which are then (possibly) overriden by the
956specifications in the <tt>datalayout</tt> keyword. The default specifications
957are given in this list:</p>
958<ul>
959 <li><tt>E</tt> - big endian</li>
960 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
961 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
962 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
963 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
964 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
965 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
966 alignment of 64-bits</li>
967 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
968 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
969 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
970 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
971 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
972</ul>
973<p>When llvm is determining the alignment for a given type, it uses the
974following rules:
975<ol>
976 <li>If the type sought is an exact match for one of the specifications, that
977 specification is used.</li>
978 <li>If no match is found, and the type sought is an integer type, then the
979 smallest integer type that is larger than the bitwidth of the sought type is
980 used. If none of the specifications are larger than the bitwidth then the the
981 largest integer type is used. For example, given the default specifications
982 above, the i7 type will use the alignment of i8 (next largest) while both
983 i65 and i256 will use the alignment of i64 (largest specified).</li>
984 <li>If no match is found, and the type sought is a vector type, then the
985 largest vector type that is smaller than the sought vector type will be used
986 as a fall back. This happens because <128 x double> can be implemented in
987 terms of 64 <2 x double>, for example.</li>
988</ol>
989</div>
990
991<!-- *********************************************************************** -->
992<div class="doc_section"> <a name="typesystem">Type System</a> </div>
993<!-- *********************************************************************** -->
994
995<div class="doc_text">
996
997<p>The LLVM type system is one of the most important features of the
998intermediate representation. Being typed enables a number of
999optimizations to be performed on the IR directly, without having to do
1000extra analyses on the side before the transformation. A strong type
1001system makes it easier to read the generated code and enables novel
1002analyses and transformations that are not feasible to perform on normal
1003three address code representations.</p>
1004
1005</div>
1006
1007<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1008<div class="doc_subsection"> <a name="t_classifications">Type
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1009Classifications</a> </div>
1010<div class="doc_text">
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1011<p>The types fall into a few useful
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1012classifications:</p>
1013
1014<table border="1" cellspacing="0" cellpadding="4">
1015 <tbody>
1016 <tr><th>Classification</th><th>Types</th></tr>
1017 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1018 <td><a href="#t_integer">integer</a></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1019 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1020 </tr>
1021 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1022 <td><a href="#t_floating">floating point</a></td>
1023 <td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1024 </tr>
1025 <tr>
1026 <td><a name="t_firstclass">first class</a></td>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1027 <td><a href="#t_integer">integer</a>,
1028 <a href="#t_floating">floating point</a>,
1029 <a href="#t_pointer">pointer</a>,
1030 <a href="#t_vector">vector</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1031 </td>
1032 </tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1033 <tr>
1034 <td><a href="#t_primitive">primitive</a></td>
1035 <td><a href="#t_label">label</a>,
1036 <a href="#t_void">void</a>,
1037 <a href="#t_integer">integer</a>,
1038 <a href="#t_floating">floating point</a>.</td>
1039 </tr>
1040 <tr>
1041 <td><a href="#t_derived">derived</a></td>
1042 <td><a href="#t_integer">integer</a>,
1043 <a href="#t_array">array</a>,
1044 <a href="#t_function">function</a>,
1045 <a href="#t_pointer">pointer</a>,
1046 <a href="#t_struct">structure</a>,
1047 <a href="#t_pstruct">packed structure</a>,
1048 <a href="#t_vector">vector</a>,
1049 <a href="#t_opaque">opaque</a>.
1050 </tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1051 </tbody>
1052</table>
1053
1054<p>The <a href="#t_firstclass">first class</a> types are perhaps the
1055most important. Values of these types are the only ones which can be
1056produced by instructions, passed as arguments, or used as operands to
1057instructions. This means that all structures and arrays must be
1058manipulated either by pointer or by component.</p>
1059</div>
1060
1061<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1062<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1063
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1064<div class="doc_text">
1065<p>The primitive types are the fundamental building blocks of the LLVM
1066system.</p>
1067
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1068</div>
1069
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1070<!-- _______________________________________________________________________ -->
1071<div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
1072
1073<div class="doc_text">
1074 <table>
1075 <tbody>
1076 <tr><th>Type</th><th>Description</th></tr>
1077 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
1078 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
1079 <tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
1080 <tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
1081 <tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
1082 </tbody>
1083 </table>
1084</div>
1085
1086<!-- _______________________________________________________________________ -->
1087<div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
1088
1089<div class="doc_text">
1090<h5>Overview:</h5>
1091<p>The void type does not represent any value and has no size.</p>
1092
1093<h5>Syntax:</h5>
1094
1095<pre>
1096 void
1097</pre>
1098</div>
1099
1100<!-- _______________________________________________________________________ -->
1101<div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
1102
1103<div class="doc_text">
1104<h5>Overview:</h5>
1105<p>The label type represents code labels.</p>
1106
1107<h5>Syntax:</h5>
1108
1109<pre>
1110 label
1111</pre>
1112</div>
1113
1114
1115<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1116<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1117
1118<div class="doc_text">
1119
1120<p>The real power in LLVM comes from the derived types in the system.
1121This is what allows a programmer to represent arrays, functions,
1122pointers, and other useful types. Note that these derived types may be
1123recursive: For example, it is possible to have a two dimensional array.</p>
1124
1125</div>
1126
1127<!-- _______________________________________________________________________ -->
1128<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1129
1130<div class="doc_text">
1131
1132<h5>Overview:</h5>
1133<p>The integer type is a very simple derived type that simply specifies an
1134arbitrary bit width for the integer type desired. Any bit width from 1 bit to
11352^23-1 (about 8 million) can be specified.</p>
1136
1137<h5>Syntax:</h5>
1138
1139<pre>
1140 iN
1141</pre>
1142
1143<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1144value.</p>
1145
1146<h5>Examples:</h5>
1147<table class="layout">
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]1148 <tbody>
1149 <tr>
1150 <td><tt>i1</tt></td>
1151 <td>a single-bit integer.</td>
1152 </tr><tr>
1153 <td><tt>i32</tt></td>
1154 <td>a 32-bit integer.</td>
1155 </tr><tr>
1156 <td><tt>i1942652</tt></td>
1157 <td>a really big integer of over 1 million bits.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1158 </tr>
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]1159 </tbody>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1160</table>
1161</div>
1162
1163<!-- _______________________________________________________________________ -->
1164<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1165
1166<div class="doc_text">
1167
1168<h5>Overview:</h5>
1169
1170<p>The array type is a very simple derived type that arranges elements
1171sequentially in memory. The array type requires a size (number of
1172elements) and an underlying data type.</p>
1173
1174<h5>Syntax:</h5>
1175
1176<pre>
1177 [&lt;# elements&gt; x &lt;elementtype&gt;]
1178</pre>
1179
1180<p>The number of elements is a constant integer value; elementtype may
1181be any type with a size.</p>
1182
1183<h5>Examples:</h5>
1184<table class="layout">
1185 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1186 <td class="left"><tt>[40 x i32]</tt></td>
1187 <td class="left">Array of 40 32-bit integer values.</td>
1188 </tr>
1189 <tr class="layout">
1190 <td class="left"><tt>[41 x i32]</tt></td>
1191 <td class="left">Array of 41 32-bit integer values.</td>
1192 </tr>
1193 <tr class="layout">
1194 <td class="left"><tt>[4 x i8]</tt></td>
1195 <td class="left">Array of 4 8-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1196 </tr>
1197</table>
1198<p>Here are some examples of multidimensional arrays:</p>
1199<table class="layout">
1200 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1201 <td class="left"><tt>[3 x [4 x i32]]</tt></td>
1202 <td class="left">3x4 array of 32-bit integer values.</td>
1203 </tr>
1204 <tr class="layout">
1205 <td class="left"><tt>[12 x [10 x float]]</tt></td>
1206 <td class="left">12x10 array of single precision floating point values.</td>
1207 </tr>
1208 <tr class="layout">
1209 <td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
1210 <td class="left">2x3x4 array of 16-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1211 </tr>
1212</table>
1213
1214<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1215length array. Normally, accesses past the end of an array are undefined in
1216LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1217As a special case, however, zero length arrays are recognized to be variable
1218length. This allows implementation of 'pascal style arrays' with the LLVM
1219type "{ i32, [0 x float]}", for example.</p>
1220
1221</div>
1222
1223<!-- _______________________________________________________________________ -->
1224<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1225<div class="doc_text">
1226<h5>Overview:</h5>
1227<p>The function type can be thought of as a function signature. It
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1228consists of a return type and a list of formal parameter types. The
Devang Pateld5404c02008-03-24 20:52:42 +0000[diff] [blame]1229return type of a function type is a scalar type or a void type or a struct type.
1230If the return type is a struct type then all struct elements must be of first
Devang Patel6dddba22008-03-24 18:10:52 +0000[diff] [blame]1231class types. Function types are usually used to build virtual function tables
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1232(which are structures of pointers to functions), for indirect function
1233calls, and when defining a function.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1234
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1235<h5>Syntax:</h5>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1236<pre> &lt;returntype list&gt; (&lt;parameter list&gt;)<br></pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1237<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
1238specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1239which indicates that the function takes a variable number of arguments.
1240Variable argument functions can access their arguments with the <a
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1241 href="#int_varargs">variable argument handling intrinsic</a> functions.
1242'<tt>&lt;returntype list&gt;</tt>' is a comma-separated list of
1243<a href="#t_firstclass">first class</a> type specifiers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1244<h5>Examples:</h5>
1245<table class="layout">
1246 <tr class="layout">
1247 <td class="left"><tt>i32 (i32)</tt></td>
1248 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1249 </td>
1250 </tr><tr class="layout">
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]1251 <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1252 </tt></td>
1253 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1254 an <tt>i16</tt> that should be sign extended and a
1255 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1256 <tt>float</tt>.
1257 </td>
1258 </tr><tr class="layout">
1259 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1260 <td class="left">A vararg function that takes at least one
1261 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1262 which returns an integer. This is the signature for <tt>printf</tt> in
1263 LLVM.
1264 </td>
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1265 </tr><tr class="layout">
1266 <td class="left"><tt>{i32, i32} (i32)</tt></td>
Devang Patel6dddba22008-03-24 18:10:52 +0000[diff] [blame]1267 <td class="left">A function taking an <tt>i32></tt>, returning two
1268 <tt> i32 </tt> values as an aggregate of type <tt>{ i32, i32 }</tt>
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1269 </td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1270 </tr>
1271</table>
1272
1273</div>
1274<!-- _______________________________________________________________________ -->
1275<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1276<div class="doc_text">
1277<h5>Overview:</h5>
1278<p>The structure type is used to represent a collection of data members
1279together in memory. The packing of the field types is defined to match
1280the ABI of the underlying processor. The elements of a structure may
1281be any type that has a size.</p>
1282<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1283and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1284field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1285instruction.</p>
1286<h5>Syntax:</h5>
1287<pre> { &lt;type list&gt; }<br></pre>
1288<h5>Examples:</h5>
1289<table class="layout">
1290 <tr class="layout">
1291 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1292 <td class="left">A triple of three <tt>i32</tt> values</td>
1293 </tr><tr class="layout">
1294 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1295 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1296 second element is a <a href="#t_pointer">pointer</a> to a
1297 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1298 an <tt>i32</tt>.</td>
1299 </tr>
1300</table>
1301</div>
1302
1303<!-- _______________________________________________________________________ -->
1304<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1305</div>
1306<div class="doc_text">
1307<h5>Overview:</h5>
1308<p>The packed structure type is used to represent a collection of data members
1309together in memory. There is no padding between fields. Further, the alignment
1310of a packed structure is 1 byte. The elements of a packed structure may
1311be any type that has a size.</p>
1312<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1313and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1314field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1315instruction.</p>
1316<h5>Syntax:</h5>
1317<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1318<h5>Examples:</h5>
1319<table class="layout">
1320 <tr class="layout">
1321 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1322 <td class="left">A triple of three <tt>i32</tt> values</td>
1323 </tr><tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1324 <td class="left"><tt>&lt; { float, i32 (i32)* } &gt;</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1325 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1326 second element is a <a href="#t_pointer">pointer</a> to a
1327 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1328 an <tt>i32</tt>.</td>
1329 </tr>
1330</table>
1331</div>
1332
1333<!-- _______________________________________________________________________ -->
1334<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1335<div class="doc_text">
1336<h5>Overview:</h5>
1337<p>As in many languages, the pointer type represents a pointer or
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]1338reference to another object, which must live in memory. Pointer types may have
1339an optional address space attribute defining the target-specific numbered
1340address space where the pointed-to object resides. The default address space is
1341zero.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1342<h5>Syntax:</h5>
1343<pre> &lt;type&gt; *<br></pre>
1344<h5>Examples:</h5>
1345<table class="layout">
1346 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1347 <td class="left"><tt>[4x i32]*</tt></td>
1348 <td class="left">A <a href="#t_pointer">pointer</a> to <a
1349 href="#t_array">array</a> of four <tt>i32</tt> values.</td>
1350 </tr>
1351 <tr class="layout">
1352 <td class="left"><tt>i32 (i32 *) *</tt></td>
1353 <td class="left"> A <a href="#t_pointer">pointer</a> to a <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1354 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1355 <tt>i32</tt>.</td>
1356 </tr>
1357 <tr class="layout">
1358 <td class="left"><tt>i32 addrspace(5)*</tt></td>
1359 <td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
1360 that resides in address space #5.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1361 </tr>
1362</table>
1363</div>
1364
1365<!-- _______________________________________________________________________ -->
1366<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1367<div class="doc_text">
1368
1369<h5>Overview:</h5>
1370
1371<p>A vector type is a simple derived type that represents a vector
1372of elements. Vector types are used when multiple primitive data
1373are operated in parallel using a single instruction (SIMD).
1374A vector type requires a size (number of
1375elements) and an underlying primitive data type. Vectors must have a power
1376of two length (1, 2, 4, 8, 16 ...). Vector types are
1377considered <a href="#t_firstclass">first class</a>.</p>
1378
1379<h5>Syntax:</h5>
1380
1381<pre>
1382 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1383</pre>
1384
1385<p>The number of elements is a constant integer value; elementtype may
1386be any integer or floating point type.</p>
1387
1388<h5>Examples:</h5>
1389
1390<table class="layout">
1391 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1392 <td class="left"><tt>&lt;4 x i32&gt;</tt></td>
1393 <td class="left">Vector of 4 32-bit integer values.</td>
1394 </tr>
1395 <tr class="layout">
1396 <td class="left"><tt>&lt;8 x float&gt;</tt></td>
1397 <td class="left">Vector of 8 32-bit floating-point values.</td>
1398 </tr>
1399 <tr class="layout">
1400 <td class="left"><tt>&lt;2 x i64&gt;</tt></td>
1401 <td class="left">Vector of 2 64-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1402 </tr>
1403</table>
1404</div>
1405
1406<!-- _______________________________________________________________________ -->
1407<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1408<div class="doc_text">
1409
1410<h5>Overview:</h5>
1411
1412<p>Opaque types are used to represent unknown types in the system. This
Gordon Henriksenda0706e2007-10-14 00:34:53 +0000[diff] [blame]1413corresponds (for example) to the C notion of a forward declared structure type.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1414In LLVM, opaque types can eventually be resolved to any type (not just a
1415structure type).</p>
1416
1417<h5>Syntax:</h5>
1418
1419<pre>
1420 opaque
1421</pre>
1422
1423<h5>Examples:</h5>
1424
1425<table class="layout">
1426 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1427 <td class="left"><tt>opaque</tt></td>
1428 <td class="left">An opaque type.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1429 </tr>
1430</table>
1431</div>
1432
1433
1434<!-- *********************************************************************** -->
1435<div class="doc_section"> <a name="constants">Constants</a> </div>
1436<!-- *********************************************************************** -->
1437
1438<div class="doc_text">
1439
1440<p>LLVM has several different basic types of constants. This section describes
1441them all and their syntax.</p>
1442
1443</div>
1444
1445<!-- ======================================================================= -->
1446<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1447
1448<div class="doc_text">
1449
1450<dl>
1451 <dt><b>Boolean constants</b></dt>
1452
1453 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1454 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1455 </dd>
1456
1457 <dt><b>Integer constants</b></dt>
1458
1459 <dd>Standard integers (such as '4') are constants of the <a
1460 href="#t_integer">integer</a> type. Negative numbers may be used with
1461 integer types.
1462 </dd>
1463
1464 <dt><b>Floating point constants</b></dt>
1465
1466 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1467 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame]1468 notation (see below). The assembler requires the exact decimal value of
1469 a floating-point constant. For example, the assembler accepts 1.25 but
1470 rejects 1.3 because 1.3 is a repeating decimal in binary. Floating point
1471 constants must have a <a href="#t_floating">floating point</a> type. </dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1472
1473 <dt><b>Null pointer constants</b></dt>
1474
1475 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1476 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1477
1478</dl>
1479
1480<p>The one non-intuitive notation for constants is the optional hexadecimal form
1481of floating point constants. For example, the form '<tt>double
14820x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
14834.5e+15</tt>'. The only time hexadecimal floating point constants are required
1484(and the only time that they are generated by the disassembler) is when a
1485floating point constant must be emitted but it cannot be represented as a
1486decimal floating point number. For example, NaN's, infinities, and other
1487special values are represented in their IEEE hexadecimal format so that
1488assembly and disassembly do not cause any bits to change in the constants.</p>
1489
1490</div>
1491
1492<!-- ======================================================================= -->
1493<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1494</div>
1495
1496<div class="doc_text">
1497<p>Aggregate constants arise from aggregation of simple constants
1498and smaller aggregate constants.</p>
1499
1500<dl>
1501 <dt><b>Structure constants</b></dt>
1502
1503 <dd>Structure constants are represented with notation similar to structure
1504 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner6c8de962007-12-25 20:34:52 +0000[diff] [blame]1505 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
1506 where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1507 must have <a href="#t_struct">structure type</a>, and the number and
1508 types of elements must match those specified by the type.
1509 </dd>
1510
1511 <dt><b>Array constants</b></dt>
1512
1513 <dd>Array constants are represented with notation similar to array type
1514 definitions (a comma separated list of elements, surrounded by square brackets
1515 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1516 constants must have <a href="#t_array">array type</a>, and the number and
1517 types of elements must match those specified by the type.
1518 </dd>
1519
1520 <dt><b>Vector constants</b></dt>
1521
1522 <dd>Vector constants are represented with notation similar to vector type
1523 definitions (a comma separated list of elements, surrounded by
1524 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1525 i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must have <a
1526 href="#t_vector">vector type</a>, and the number and types of elements must
1527 match those specified by the type.
1528 </dd>
1529
1530 <dt><b>Zero initialization</b></dt>
1531
1532 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1533 value to zero of <em>any</em> type, including scalar and aggregate types.
1534 This is often used to avoid having to print large zero initializers (e.g. for
1535 large arrays) and is always exactly equivalent to using explicit zero
1536 initializers.
1537 </dd>
1538</dl>
1539
1540</div>
1541
1542<!-- ======================================================================= -->
1543<div class="doc_subsection">
1544 <a name="globalconstants">Global Variable and Function Addresses</a>
1545</div>
1546
1547<div class="doc_text">
1548
1549<p>The addresses of <a href="#globalvars">global variables</a> and <a
1550href="#functionstructure">functions</a> are always implicitly valid (link-time)
1551constants. These constants are explicitly referenced when the <a
1552href="#identifiers">identifier for the global</a> is used and always have <a
1553href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1554file:</p>
1555
1556<div class="doc_code">
1557<pre>
1558@X = global i32 17
1559@Y = global i32 42
1560@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1561</pre>
1562</div>
1563
1564</div>
1565
1566<!-- ======================================================================= -->
1567<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1568<div class="doc_text">
1569 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1570 no specific value. Undefined values may be of any type and be used anywhere
1571 a constant is permitted.</p>
1572
1573 <p>Undefined values indicate to the compiler that the program is well defined
1574 no matter what value is used, giving the compiler more freedom to optimize.
1575 </p>
1576</div>
1577
1578<!-- ======================================================================= -->
1579<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1580</div>
1581
1582<div class="doc_text">
1583
1584<p>Constant expressions are used to allow expressions involving other constants
1585to be used as constants. Constant expressions may be of any <a
1586href="#t_firstclass">first class</a> type and may involve any LLVM operation
1587that does not have side effects (e.g. load and call are not supported). The
1588following is the syntax for constant expressions:</p>
1589
1590<dl>
1591 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1592 <dd>Truncate a constant to another type. The bit size of CST must be larger
1593 than the bit size of TYPE. Both types must be integers.</dd>
1594
1595 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1596 <dd>Zero extend a constant to another type. The bit size of CST must be
1597 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1598
1599 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1600 <dd>Sign extend a constant to another type. The bit size of CST must be
1601 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1602
1603 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1604 <dd>Truncate a floating point constant to another floating point type. The
1605 size of CST must be larger than the size of TYPE. Both types must be
1606 floating point.</dd>
1607
1608 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1609 <dd>Floating point extend a constant to another type. The size of CST must be
1610 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1611
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]1612 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1613 <dd>Convert a floating point constant to the corresponding unsigned integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1614 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1615 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1616 of the same number of elements. If the value won't fit in the integer type,
1617 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1618
1619 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1620 <dd>Convert a floating point constant to the corresponding signed integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1621 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1622 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1623 of the same number of elements. If the value won't fit in the integer type,
1624 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1625
1626 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1627 <dd>Convert an unsigned integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1628 constant. TYPE must be a scalar or vector floating point type. CST must be of
1629 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1630 of the same number of elements. If the value won't fit in the floating point
1631 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1632
1633 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
1634 <dd>Convert a signed integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1635 constant. TYPE must be a scalar or vector floating point type. CST must be of
1636 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1637 of the same number of elements. If the value won't fit in the floating point
1638 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1639
1640 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1641 <dd>Convert a pointer typed constant to the corresponding integer constant
1642 TYPE must be an integer type. CST must be of pointer type. The CST value is
1643 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1644
1645 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1646 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1647 pointer type. CST must be of integer type. The CST value is zero extended,
1648 truncated, or unchanged to make it fit in a pointer size. This one is
1649 <i>really</i> dangerous!</dd>
1650
1651 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
1652 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1653 identical (same number of bits). The conversion is done as if the CST value
1654 was stored to memory and read back as TYPE. In other words, no bits change
1655 with this operator, just the type. This can be used for conversion of
1656 vector types to any other type, as long as they have the same bit width. For
1657 pointers it is only valid to cast to another pointer type.
1658 </dd>
1659
1660 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1661
1662 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1663 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1664 instruction, the index list may have zero or more indexes, which are required
1665 to make sense for the type of "CSTPTR".</dd>
1666
1667 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1668
1669 <dd>Perform the <a href="#i_select">select operation</a> on
1670 constants.</dd>
1671
1672 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1673 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1674
1675 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1676 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
1677
1678 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1679
1680 <dd>Perform the <a href="#i_extractelement">extractelement
1681 operation</a> on constants.
1682
1683 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1684
1685 <dd>Perform the <a href="#i_insertelement">insertelement
1686 operation</a> on constants.</dd>
1687
1688
1689 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1690
1691 <dd>Perform the <a href="#i_shufflevector">shufflevector
1692 operation</a> on constants.</dd>
1693
1694 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1695
1696 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1697 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
1698 binary</a> operations. The constraints on operands are the same as those for
1699 the corresponding instruction (e.g. no bitwise operations on floating point
1700 values are allowed).</dd>
1701</dl>
1702</div>
1703
1704<!-- *********************************************************************** -->
1705<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1706<!-- *********************************************************************** -->
1707
1708<!-- ======================================================================= -->
1709<div class="doc_subsection">
1710<a name="inlineasm">Inline Assembler Expressions</a>
1711</div>
1712
1713<div class="doc_text">
1714
1715<p>
1716LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1717Module-Level Inline Assembly</a>) through the use of a special value. This
1718value represents the inline assembler as a string (containing the instructions
1719to emit), a list of operand constraints (stored as a string), and a flag that
1720indicates whether or not the inline asm expression has side effects. An example
1721inline assembler expression is:
1722</p>
1723
1724<div class="doc_code">
1725<pre>
1726i32 (i32) asm "bswap $0", "=r,r"
1727</pre>
1728</div>
1729
1730<p>
1731Inline assembler expressions may <b>only</b> be used as the callee operand of
1732a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1733</p>
1734
1735<div class="doc_code">
1736<pre>
1737%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
1738</pre>
1739</div>
1740
1741<p>
1742Inline asms with side effects not visible in the constraint list must be marked
1743as having side effects. This is done through the use of the
1744'<tt>sideeffect</tt>' keyword, like so:
1745</p>
1746
1747<div class="doc_code">
1748<pre>
1749call void asm sideeffect "eieio", ""()
1750</pre>
1751</div>
1752
1753<p>TODO: The format of the asm and constraints string still need to be
1754documented here. Constraints on what can be done (e.g. duplication, moving, etc
1755need to be documented).
1756</p>
1757
1758</div>
1759
1760<!-- *********************************************************************** -->
1761<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1762<!-- *********************************************************************** -->
1763
1764<div class="doc_text">
1765
1766<p>The LLVM instruction set consists of several different
1767classifications of instructions: <a href="#terminators">terminator
1768instructions</a>, <a href="#binaryops">binary instructions</a>,
1769<a href="#bitwiseops">bitwise binary instructions</a>, <a
1770 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1771instructions</a>.</p>
1772
1773</div>
1774
1775<!-- ======================================================================= -->
1776<div class="doc_subsection"> <a name="terminators">Terminator
1777Instructions</a> </div>
1778
1779<div class="doc_text">
1780
1781<p>As mentioned <a href="#functionstructure">previously</a>, every
1782basic block in a program ends with a "Terminator" instruction, which
1783indicates which block should be executed after the current block is
1784finished. These terminator instructions typically yield a '<tt>void</tt>'
1785value: they produce control flow, not values (the one exception being
1786the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
1787<p>There are six different terminator instructions: the '<a
1788 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1789instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
1790the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1791 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1792 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
1793
1794</div>
1795
1796<!-- _______________________________________________________________________ -->
1797<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1798Instruction</a> </div>
1799<div class="doc_text">
1800<h5>Syntax:</h5>
1801<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
1802 ret void <i>; Return from void function</i>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1803 ret &lt;type&gt; &lt;value&gt;, &lt;type&gt; &lt;value&gt; <i>; Return two values from a non-void function </i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1804</pre>
1805<h5>Overview:</h5>
1806<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1807value) from a function back to the caller.</p>
1808<p>There are two forms of the '<tt>ret</tt>' instruction: one that
1809returns a value and then causes control flow, and one that just causes
1810control flow to occur.</p>
1811<h5>Arguments:</h5>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1812<p>The '<tt>ret</tt>' instruction may return one or multiple values. The
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1813type of each return value must be a '<a href="#t_firstclass">first class</a>'
1814 type. Note that a function is not <a href="#wellformed">well formed</a>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1815if there exists a '<tt>ret</tt>' instruction inside of the function that
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1816returns values that do not match the return type of the function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1817<h5>Semantics:</h5>
1818<p>When the '<tt>ret</tt>' instruction is executed, control flow
1819returns back to the calling function's context. If the caller is a "<a
1820 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
1821the instruction after the call. If the caller was an "<a
1822 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1823at the beginning of the "normal" destination block. If the instruction
1824returns a value, that value shall set the call or invoke instruction's
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1825return value. If the instruction returns multiple values then these
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1826values can only be accessed through a '<a href="#i_getresult"><tt>getresult</tt>
1827</a>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1828<h5>Example:</h5>
1829<pre> ret i32 5 <i>; Return an integer value of 5</i>
1830 ret void <i>; Return from a void function</i>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1831 ret i32 4, i8 2 <i>; Return two values 4 and 2 </i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1832</pre>
1833</div>
1834<!-- _______________________________________________________________________ -->
1835<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
1836<div class="doc_text">
1837<h5>Syntax:</h5>
1838<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
1839</pre>
1840<h5>Overview:</h5>
1841<p>The '<tt>br</tt>' instruction is used to cause control flow to
1842transfer to a different basic block in the current function. There are
1843two forms of this instruction, corresponding to a conditional branch
1844and an unconditional branch.</p>
1845<h5>Arguments:</h5>
1846<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1847single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
1848unconditional form of the '<tt>br</tt>' instruction takes a single
1849'<tt>label</tt>' value as a target.</p>
1850<h5>Semantics:</h5>
1851<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
1852argument is evaluated. If the value is <tt>true</tt>, control flows
1853to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1854control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
1855<h5>Example:</h5>
1856<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
1857 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
1858</div>
1859<!-- _______________________________________________________________________ -->
1860<div class="doc_subsubsection">
1861 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1862</div>
1863
1864<div class="doc_text">
1865<h5>Syntax:</h5>
1866
1867<pre>
1868 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1869</pre>
1870
1871<h5>Overview:</h5>
1872
1873<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1874several different places. It is a generalization of the '<tt>br</tt>'
1875instruction, allowing a branch to occur to one of many possible
1876destinations.</p>
1877
1878
1879<h5>Arguments:</h5>
1880
1881<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1882comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1883an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1884table is not allowed to contain duplicate constant entries.</p>
1885
1886<h5>Semantics:</h5>
1887
1888<p>The <tt>switch</tt> instruction specifies a table of values and
1889destinations. When the '<tt>switch</tt>' instruction is executed, this
1890table is searched for the given value. If the value is found, control flow is
1891transfered to the corresponding destination; otherwise, control flow is
1892transfered to the default destination.</p>
1893
1894<h5>Implementation:</h5>
1895
1896<p>Depending on properties of the target machine and the particular
1897<tt>switch</tt> instruction, this instruction may be code generated in different
1898ways. For example, it could be generated as a series of chained conditional
1899branches or with a lookup table.</p>
1900
1901<h5>Example:</h5>
1902
1903<pre>
1904 <i>; Emulate a conditional br instruction</i>
1905 %Val = <a href="#i_zext">zext</a> i1 %value to i32
1906 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
1907
1908 <i>; Emulate an unconditional br instruction</i>
1909 switch i32 0, label %dest [ ]
1910
1911 <i>; Implement a jump table:</i>
1912 switch i32 %val, label %otherwise [ i32 0, label %onzero
1913 i32 1, label %onone
1914 i32 2, label %ontwo ]
1915</pre>
1916</div>
1917
1918<!-- _______________________________________________________________________ -->
1919<div class="doc_subsubsection">
1920 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1921</div>
1922
1923<div class="doc_text">
1924
1925<h5>Syntax:</h5>
1926
1927<pre>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]1928 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; &lt;function ptr val&gt;(&lt;function args&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1929 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
1930</pre>
1931
1932<h5>Overview:</h5>
1933
1934<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1935function, with the possibility of control flow transfer to either the
1936'<tt>normal</tt>' label or the
1937'<tt>exception</tt>' label. If the callee function returns with the
1938"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1939"normal" label. If the callee (or any indirect callees) returns with the "<a
1940href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1941continued at the dynamically nearest "exception" label. If the callee function
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1942returns multiple values then individual return values are only accessible through
1943a '<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1944
1945<h5>Arguments:</h5>
1946
1947<p>This instruction requires several arguments:</p>
1948
1949<ol>
1950 <li>
1951 The optional "cconv" marker indicates which <a href="#callingconv">calling
1952 convention</a> the call should use. If none is specified, the call defaults
1953 to using C calling conventions.
1954 </li>
1955 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1956 function value being invoked. In most cases, this is a direct function
1957 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1958 an arbitrary pointer to function value.
1959 </li>
1960
1961 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1962 function to be invoked. </li>
1963
1964 <li>'<tt>function args</tt>': argument list whose types match the function
1965 signature argument types. If the function signature indicates the function
1966 accepts a variable number of arguments, the extra arguments can be
1967 specified. </li>
1968
1969 <li>'<tt>normal label</tt>': the label reached when the called function
1970 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1971
1972 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1973 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1974
1975</ol>
1976
1977<h5>Semantics:</h5>
1978
1979<p>This instruction is designed to operate as a standard '<tt><a
1980href="#i_call">call</a></tt>' instruction in most regards. The primary
1981difference is that it establishes an association with a label, which is used by
1982the runtime library to unwind the stack.</p>
1983
1984<p>This instruction is used in languages with destructors to ensure that proper
1985cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1986exception. Additionally, this is important for implementation of
1987'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1988
1989<h5>Example:</h5>
1990<pre>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]1991 %retval = invoke i32 @Test(i32 15) to label %Continue
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1992 unwind label %TestCleanup <i>; {i32}:retval set</i>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]1993 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Testfnptr(i32 15) to label %Continue
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1994 unwind label %TestCleanup <i>; {i32}:retval set</i>
1995</pre>
1996</div>
1997
1998
1999<!-- _______________________________________________________________________ -->
2000
2001<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
2002Instruction</a> </div>
2003
2004<div class="doc_text">
2005
2006<h5>Syntax:</h5>
2007<pre>
2008 unwind
2009</pre>
2010
2011<h5>Overview:</h5>
2012
2013<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
2014at the first callee in the dynamic call stack which used an <a
2015href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
2016primarily used to implement exception handling.</p>
2017
2018<h5>Semantics:</h5>
2019
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2020<p>The '<tt>unwind</tt>' instruction causes execution of the current function to
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2021immediately halt. The dynamic call stack is then searched for the first <a
2022href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
2023execution continues at the "exceptional" destination block specified by the
2024<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
2025dynamic call chain, undefined behavior results.</p>
2026</div>
2027
2028<!-- _______________________________________________________________________ -->
2029
2030<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
2031Instruction</a> </div>
2032
2033<div class="doc_text">
2034
2035<h5>Syntax:</h5>
2036<pre>
2037 unreachable
2038</pre>
2039
2040<h5>Overview:</h5>
2041
2042<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
2043instruction is used to inform the optimizer that a particular portion of the
2044code is not reachable. This can be used to indicate that the code after a
2045no-return function cannot be reached, and other facts.</p>
2046
2047<h5>Semantics:</h5>
2048
2049<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
2050</div>
2051
2052
2053
2054<!-- ======================================================================= -->
2055<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
2056<div class="doc_text">
2057<p>Binary operators are used to do most of the computation in a
Chris Lattnerab596d92008-04-01 18:47:32 +0000[diff] [blame]2058program. They require two operands of the same type, execute an operation on them, and
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2059produce a single value. The operands might represent
2060multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
Chris Lattnerab596d92008-04-01 18:47:32 +0000[diff] [blame]2061The result value has the same type as its operands.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2062<p>There are several different binary operators:</p>
2063</div>
2064<!-- _______________________________________________________________________ -->
2065<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
2066Instruction</a> </div>
2067<div class="doc_text">
2068<h5>Syntax:</h5>
2069<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2070</pre>
2071<h5>Overview:</h5>
2072<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
2073<h5>Arguments:</h5>
2074<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
2075 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
2076 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2077Both arguments must have identical types.</p>
2078<h5>Semantics:</h5>
2079<p>The value produced is the integer or floating point sum of the two
2080operands.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2081<p>If an integer sum has unsigned overflow, the result returned is the
2082mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2083the result.</p>
2084<p>Because LLVM integers use a two's complement representation, this
2085instruction is appropriate for both signed and unsigned integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2086<h5>Example:</h5>
2087<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
2088</pre>
2089</div>
2090<!-- _______________________________________________________________________ -->
2091<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
2092Instruction</a> </div>
2093<div class="doc_text">
2094<h5>Syntax:</h5>
2095<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2096</pre>
2097<h5>Overview:</h5>
2098<p>The '<tt>sub</tt>' instruction returns the difference of its two
2099operands.</p>
2100<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
2101instruction present in most other intermediate representations.</p>
2102<h5>Arguments:</h5>
2103<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
2104 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2105values.
2106This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2107Both arguments must have identical types.</p>
2108<h5>Semantics:</h5>
2109<p>The value produced is the integer or floating point difference of
2110the two operands.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2111<p>If an integer difference has unsigned overflow, the result returned is the
2112mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2113the result.</p>
2114<p>Because LLVM integers use a two's complement representation, this
2115instruction is appropriate for both signed and unsigned integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2116<h5>Example:</h5>
2117<pre>
2118 &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2119 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2120</pre>
2121</div>
2122<!-- _______________________________________________________________________ -->
2123<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
2124Instruction</a> </div>
2125<div class="doc_text">
2126<h5>Syntax:</h5>
2127<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2128</pre>
2129<h5>Overview:</h5>
2130<p>The '<tt>mul</tt>' instruction returns the product of its two
2131operands.</p>
2132<h5>Arguments:</h5>
2133<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
2134 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2135values.
2136This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2137Both arguments must have identical types.</p>
2138<h5>Semantics:</h5>
2139<p>The value produced is the integer or floating point product of the
2140two operands.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2141<p>If the result of an integer multiplication has unsigned overflow,
2142the result returned is the mathematical result modulo
21432<sup>n</sup>, where n is the bit width of the result.</p>
2144<p>Because LLVM integers use a two's complement representation, and the
2145result is the same width as the operands, this instruction returns the
2146correct result for both signed and unsigned integers. If a full product
2147(e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands
2148should be sign-extended or zero-extended as appropriate to the
2149width of the full product.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2150<h5>Example:</h5>
2151<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2152</pre>
2153</div>
2154<!-- _______________________________________________________________________ -->
2155<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2156</a></div>
2157<div class="doc_text">
2158<h5>Syntax:</h5>
2159<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2160</pre>
2161<h5>Overview:</h5>
2162<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2163operands.</p>
2164<h5>Arguments:</h5>
2165<p>The two arguments to the '<tt>udiv</tt>' instruction must be
2166<a href="#t_integer">integer</a> values. Both arguments must have identical
2167types. This instruction can also take <a href="#t_vector">vector</a> versions
2168of the values in which case the elements must be integers.</p>
2169<h5>Semantics:</h5>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2170<p>The value produced is the unsigned integer quotient of the two operands.</p>
2171<p>Note that unsigned integer division and signed integer division are distinct
2172operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
2173<p>Division by zero leads to undefined behavior.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2174<h5>Example:</h5>
2175<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2176</pre>
2177</div>
2178<!-- _______________________________________________________________________ -->
2179<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2180</a> </div>
2181<div class="doc_text">
2182<h5>Syntax:</h5>
2183<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2184</pre>
2185<h5>Overview:</h5>
2186<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2187operands.</p>
2188<h5>Arguments:</h5>
2189<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2190<a href="#t_integer">integer</a> values. Both arguments must have identical
2191types. This instruction can also take <a href="#t_vector">vector</a> versions
2192of the values in which case the elements must be integers.</p>
2193<h5>Semantics:</h5>
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame]2194<p>The value produced is the signed integer quotient of the two operands rounded towards zero.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2195<p>Note that signed integer division and unsigned integer division are distinct
2196operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
2197<p>Division by zero leads to undefined behavior. Overflow also leads to
2198undefined behavior; this is a rare case, but can occur, for example,
2199by doing a 32-bit division of -2147483648 by -1.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2200<h5>Example:</h5>
2201<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2202</pre>
2203</div>
2204<!-- _______________________________________________________________________ -->
2205<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2206Instruction</a> </div>
2207<div class="doc_text">
2208<h5>Syntax:</h5>
2209<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2210</pre>
2211<h5>Overview:</h5>
2212<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2213operands.</p>
2214<h5>Arguments:</h5>
2215<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2216<a href="#t_floating">floating point</a> values. Both arguments must have
2217identical types. This instruction can also take <a href="#t_vector">vector</a>
2218versions of floating point values.</p>
2219<h5>Semantics:</h5>
2220<p>The value produced is the floating point quotient of the two operands.</p>
2221<h5>Example:</h5>
2222<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2223</pre>
2224</div>
2225<!-- _______________________________________________________________________ -->
2226<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2227</div>
2228<div class="doc_text">
2229<h5>Syntax:</h5>
2230<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2231</pre>
2232<h5>Overview:</h5>
2233<p>The '<tt>urem</tt>' instruction returns the remainder from the
2234unsigned division of its two arguments.</p>
2235<h5>Arguments:</h5>
2236<p>The two arguments to the '<tt>urem</tt>' instruction must be
2237<a href="#t_integer">integer</a> values. Both arguments must have identical
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2238types. This instruction can also take <a href="#t_vector">vector</a> versions
2239of the values in which case the elements must be integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2240<h5>Semantics:</h5>
2241<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame]2242This instruction always performs an unsigned division to get the remainder.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2243<p>Note that unsigned integer remainder and signed integer remainder are
2244distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
2245<p>Taking the remainder of a division by zero leads to undefined behavior.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2246<h5>Example:</h5>
2247<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2248</pre>
2249
2250</div>
2251<!-- _______________________________________________________________________ -->
2252<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
2253Instruction</a> </div>
2254<div class="doc_text">
2255<h5>Syntax:</h5>
2256<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2257</pre>
2258<h5>Overview:</h5>
2259<p>The '<tt>srem</tt>' instruction returns the remainder from the
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2260signed division of its two operands. This instruction can also take
2261<a href="#t_vector">vector</a> versions of the values in which case
2262the elements must be integers.</p>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]2263
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2264<h5>Arguments:</h5>
2265<p>The two arguments to the '<tt>srem</tt>' instruction must be
2266<a href="#t_integer">integer</a> values. Both arguments must have identical
2267types.</p>
2268<h5>Semantics:</h5>
2269<p>This instruction returns the <i>remainder</i> of a division (where the result
2270has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2271operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2272a value. For more information about the difference, see <a
2273 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2274Math Forum</a>. For a table of how this is implemented in various languages,
2275please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2276Wikipedia: modulo operation</a>.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2277<p>Note that signed integer remainder and unsigned integer remainder are
2278distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
2279<p>Taking the remainder of a division by zero leads to undefined behavior.
2280Overflow also leads to undefined behavior; this is a rare case, but can occur,
2281for example, by taking the remainder of a 32-bit division of -2147483648 by -1.
2282(The remainder doesn't actually overflow, but this rule lets srem be
2283implemented using instructions that return both the result of the division
2284and the remainder.)</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2285<h5>Example:</h5>
2286<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2287</pre>
2288
2289</div>
2290<!-- _______________________________________________________________________ -->
2291<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2292Instruction</a> </div>
2293<div class="doc_text">
2294<h5>Syntax:</h5>
2295<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2296</pre>
2297<h5>Overview:</h5>
2298<p>The '<tt>frem</tt>' instruction returns the remainder from the
2299division of its two operands.</p>
2300<h5>Arguments:</h5>
2301<p>The two arguments to the '<tt>frem</tt>' instruction must be
2302<a href="#t_floating">floating point</a> values. Both arguments must have
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2303identical types. This instruction can also take <a href="#t_vector">vector</a>
2304versions of floating point values.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2305<h5>Semantics:</h5>
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame]2306<p>This instruction returns the <i>remainder</i> of a division.
2307The remainder has the same sign as the dividend.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2308<h5>Example:</h5>
2309<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2310</pre>
2311</div>
2312
2313<!-- ======================================================================= -->
2314<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2315Operations</a> </div>
2316<div class="doc_text">
2317<p>Bitwise binary operators are used to do various forms of
2318bit-twiddling in a program. They are generally very efficient
2319instructions and can commonly be strength reduced from other
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame]2320instructions. They require two operands of the same type, execute an operation on them,
2321and produce a single value. The resulting value is the same type as its operands.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2322</div>
2323
2324<!-- _______________________________________________________________________ -->
2325<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2326Instruction</a> </div>
2327<div class="doc_text">
2328<h5>Syntax:</h5>
2329<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2330</pre>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2331
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2332<h5>Overview:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2333
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2334<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2335the left a specified number of bits.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2336
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2337<h5>Arguments:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2338
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2339<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2340 href="#t_integer">integer</a> type. '<tt>var2</tt>' is treated as an
2341unsigned value.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2342
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2343<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2344
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame]2345<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup> mod 2<sup>n</sup>,
2346where n is the width of the result. If <tt>var2</tt> is (statically or dynamically) negative or
2347equal to or larger than the number of bits in <tt>var1</tt>, the result is undefined.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2348
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2349<h5>Example:</h5><pre>
2350 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2351 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2352 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2353 &lt;result&gt; = shl i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2354</pre>
2355</div>
2356<!-- _______________________________________________________________________ -->
2357<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2358Instruction</a> </div>
2359<div class="doc_text">
2360<h5>Syntax:</h5>
2361<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2362</pre>
2363
2364<h5>Overview:</h5>
2365<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2366operand shifted to the right a specified number of bits with zero fill.</p>
2367
2368<h5>Arguments:</h5>
2369<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2370<a href="#t_integer">integer</a> type. '<tt>var2</tt>' is treated as an
2371unsigned value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2372
2373<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2374
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2375<p>This instruction always performs a logical shift right operation. The most
2376significant bits of the result will be filled with zero bits after the
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2377shift. If <tt>var2</tt> is (statically or dynamically) equal to or larger than
2378the number of bits in <tt>var1</tt>, the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2379
2380<h5>Example:</h5>
2381<pre>
2382 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2383 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2384 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2385 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2386 &lt;result&gt; = lshr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2387</pre>
2388</div>
2389
2390<!-- _______________________________________________________________________ -->
2391<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2392Instruction</a> </div>
2393<div class="doc_text">
2394
2395<h5>Syntax:</h5>
2396<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2397</pre>
2398
2399<h5>Overview:</h5>
2400<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2401operand shifted to the right a specified number of bits with sign extension.</p>
2402
2403<h5>Arguments:</h5>
2404<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2405<a href="#t_integer">integer</a> type. '<tt>var2</tt>' is treated as an
2406unsigned value.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2407
2408<h5>Semantics:</h5>
2409<p>This instruction always performs an arithmetic shift right operation,
2410The most significant bits of the result will be filled with the sign bit
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2411of <tt>var1</tt>. If <tt>var2</tt> is (statically or dynamically) equal to or
2412larger than the number of bits in <tt>var1</tt>, the result is undefined.
2413</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2414
2415<h5>Example:</h5>
2416<pre>
2417 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2418 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2419 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2420 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2421 &lt;result&gt; = ashr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2422</pre>
2423</div>
2424
2425<!-- _______________________________________________________________________ -->
2426<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2427Instruction</a> </div>
2428<div class="doc_text">
2429<h5>Syntax:</h5>
2430<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2431</pre>
2432<h5>Overview:</h5>
2433<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2434its two operands.</p>
2435<h5>Arguments:</h5>
2436<p>The two arguments to the '<tt>and</tt>' instruction must be <a
2437 href="#t_integer">integer</a> values. Both arguments must have
2438identical types.</p>
2439<h5>Semantics:</h5>
2440<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
2441<p> </p>
2442<div style="align: center">
2443<table border="1" cellspacing="0" cellpadding="4">
2444 <tbody>
2445 <tr>
2446 <td>In0</td>
2447 <td>In1</td>
2448 <td>Out</td>
2449 </tr>
2450 <tr>
2451 <td>0</td>
2452 <td>0</td>
2453 <td>0</td>
2454 </tr>
2455 <tr>
2456 <td>0</td>
2457 <td>1</td>
2458 <td>0</td>
2459 </tr>
2460 <tr>
2461 <td>1</td>
2462 <td>0</td>
2463 <td>0</td>
2464 </tr>
2465 <tr>
2466 <td>1</td>
2467 <td>1</td>
2468 <td>1</td>
2469 </tr>
2470 </tbody>
2471</table>
2472</div>
2473<h5>Example:</h5>
2474<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2475 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2476 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
2477</pre>
2478</div>
2479<!-- _______________________________________________________________________ -->
2480<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
2481<div class="doc_text">
2482<h5>Syntax:</h5>
2483<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2484</pre>
2485<h5>Overview:</h5>
2486<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2487or of its two operands.</p>
2488<h5>Arguments:</h5>
2489<p>The two arguments to the '<tt>or</tt>' instruction must be <a
2490 href="#t_integer">integer</a> values. Both arguments must have
2491identical types.</p>
2492<h5>Semantics:</h5>
2493<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
2494<p> </p>
2495<div style="align: center">
2496<table border="1" cellspacing="0" cellpadding="4">
2497 <tbody>
2498 <tr>
2499 <td>In0</td>
2500 <td>In1</td>
2501 <td>Out</td>
2502 </tr>
2503 <tr>
2504 <td>0</td>
2505 <td>0</td>
2506 <td>0</td>
2507 </tr>
2508 <tr>
2509 <td>0</td>
2510 <td>1</td>
2511 <td>1</td>
2512 </tr>
2513 <tr>
2514 <td>1</td>
2515 <td>0</td>
2516 <td>1</td>
2517 </tr>
2518 <tr>
2519 <td>1</td>
2520 <td>1</td>
2521 <td>1</td>
2522 </tr>
2523 </tbody>
2524</table>
2525</div>
2526<h5>Example:</h5>
2527<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2528 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2529 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
2530</pre>
2531</div>
2532<!-- _______________________________________________________________________ -->
2533<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2534Instruction</a> </div>
2535<div class="doc_text">
2536<h5>Syntax:</h5>
2537<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2538</pre>
2539<h5>Overview:</h5>
2540<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2541or of its two operands. The <tt>xor</tt> is used to implement the
2542"one's complement" operation, which is the "~" operator in C.</p>
2543<h5>Arguments:</h5>
2544<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
2545 href="#t_integer">integer</a> values. Both arguments must have
2546identical types.</p>
2547<h5>Semantics:</h5>
2548<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
2549<p> </p>
2550<div style="align: center">
2551<table border="1" cellspacing="0" cellpadding="4">
2552 <tbody>
2553 <tr>
2554 <td>In0</td>
2555 <td>In1</td>
2556 <td>Out</td>
2557 </tr>
2558 <tr>
2559 <td>0</td>
2560 <td>0</td>
2561 <td>0</td>
2562 </tr>
2563 <tr>
2564 <td>0</td>
2565 <td>1</td>
2566 <td>1</td>
2567 </tr>
2568 <tr>
2569 <td>1</td>
2570 <td>0</td>
2571 <td>1</td>
2572 </tr>
2573 <tr>
2574 <td>1</td>
2575 <td>1</td>
2576 <td>0</td>
2577 </tr>
2578 </tbody>
2579</table>
2580</div>
2581<p> </p>
2582<h5>Example:</h5>
2583<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2584 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2585 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2586 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
2587</pre>
2588</div>
2589
2590<!-- ======================================================================= -->
2591<div class="doc_subsection">
2592 <a name="vectorops">Vector Operations</a>
2593</div>
2594
2595<div class="doc_text">
2596
2597<p>LLVM supports several instructions to represent vector operations in a
2598target-independent manner. These instructions cover the element-access and
2599vector-specific operations needed to process vectors effectively. While LLVM
2600does directly support these vector operations, many sophisticated algorithms
2601will want to use target-specific intrinsics to take full advantage of a specific
2602target.</p>
2603
2604</div>
2605
2606<!-- _______________________________________________________________________ -->
2607<div class="doc_subsubsection">
2608 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2609</div>
2610
2611<div class="doc_text">
2612
2613<h5>Syntax:</h5>
2614
2615<pre>
2616 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2617</pre>
2618
2619<h5>Overview:</h5>
2620
2621<p>
2622The '<tt>extractelement</tt>' instruction extracts a single scalar
2623element from a vector at a specified index.
2624</p>
2625
2626
2627<h5>Arguments:</h5>
2628
2629<p>
2630The first operand of an '<tt>extractelement</tt>' instruction is a
2631value of <a href="#t_vector">vector</a> type. The second operand is
2632an index indicating the position from which to extract the element.
2633The index may be a variable.</p>
2634
2635<h5>Semantics:</h5>
2636
2637<p>
2638The result is a scalar of the same type as the element type of
2639<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2640<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2641results are undefined.
2642</p>
2643
2644<h5>Example:</h5>
2645
2646<pre>
2647 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
2648</pre>
2649</div>
2650
2651
2652<!-- _______________________________________________________________________ -->
2653<div class="doc_subsubsection">
2654 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2655</div>
2656
2657<div class="doc_text">
2658
2659<h5>Syntax:</h5>
2660
2661<pre>
2662 &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>
2663</pre>
2664
2665<h5>Overview:</h5>
2666
2667<p>
2668The '<tt>insertelement</tt>' instruction inserts a scalar
2669element into a vector at a specified index.
2670</p>
2671
2672
2673<h5>Arguments:</h5>
2674
2675<p>
2676The first operand of an '<tt>insertelement</tt>' instruction is a
2677value of <a href="#t_vector">vector</a> type. The second operand is a
2678scalar value whose type must equal the element type of the first
2679operand. The third operand is an index indicating the position at
2680which to insert the value. The index may be a variable.</p>
2681
2682<h5>Semantics:</h5>
2683
2684<p>
2685The result is a vector of the same type as <tt>val</tt>. Its
2686element values are those of <tt>val</tt> except at position
2687<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2688exceeds the length of <tt>val</tt>, the results are undefined.
2689</p>
2690
2691<h5>Example:</h5>
2692
2693<pre>
2694 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
2695</pre>
2696</div>
2697
2698<!-- _______________________________________________________________________ -->
2699<div class="doc_subsubsection">
2700 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2701</div>
2702
2703<div class="doc_text">
2704
2705<h5>Syntax:</h5>
2706
2707<pre>
2708 &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>
2709</pre>
2710
2711<h5>Overview:</h5>
2712
2713<p>
2714The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2715from two input vectors, returning a vector of the same type.
2716</p>
2717
2718<h5>Arguments:</h5>
2719
2720<p>
2721The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2722with types that match each other and types that match the result of the
2723instruction. The third argument is a shuffle mask, which has the same number
2724of elements as the other vector type, but whose element type is always 'i32'.
2725</p>
2726
2727<p>
2728The shuffle mask operand is required to be a constant vector with either
2729constant integer or undef values.
2730</p>
2731
2732<h5>Semantics:</h5>
2733
2734<p>
2735The elements of the two input vectors are numbered from left to right across
2736both of the vectors. The shuffle mask operand specifies, for each element of
2737the result vector, which element of the two input registers the result element
2738gets. The element selector may be undef (meaning "don't care") and the second
2739operand may be undef if performing a shuffle from only one vector.
2740</p>
2741
2742<h5>Example:</h5>
2743
2744<pre>
2745 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2746 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2747 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2748 &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.
2749</pre>
2750</div>
2751
2752
2753<!-- ======================================================================= -->
2754<div class="doc_subsection">
2755 <a name="memoryops">Memory Access and Addressing Operations</a>
2756</div>
2757
2758<div class="doc_text">
2759
2760<p>A key design point of an SSA-based representation is how it
2761represents memory. In LLVM, no memory locations are in SSA form, which
2762makes things very simple. This section describes how to read, write,
2763allocate, and free memory in LLVM.</p>
2764
2765</div>
2766
2767<!-- _______________________________________________________________________ -->
2768<div class="doc_subsubsection">
2769 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2770</div>
2771
2772<div class="doc_text">
2773
2774<h5>Syntax:</h5>
2775
2776<pre>
2777 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2778</pre>
2779
2780<h5>Overview:</h5>
2781
2782<p>The '<tt>malloc</tt>' instruction allocates memory from the system
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]2783heap and returns a pointer to it. The object is always allocated in the generic
2784address space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2785
2786<h5>Arguments:</h5>
2787
2788<p>The '<tt>malloc</tt>' instruction allocates
2789<tt>sizeof(&lt;type&gt;)*NumElements</tt>
2790bytes of memory from the operating system and returns a pointer of the
2791appropriate type to the program. If "NumElements" is specified, it is the
Gabor Greif5082cf42008-02-09 22:24:34 +0000[diff] [blame]2792number of elements allocated, otherwise "NumElements" is defaulted to be one.
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2793If a constant alignment is specified, the value result of the allocation is guaranteed to
Gabor Greif5082cf42008-02-09 22:24:34 +0000[diff] [blame]2794be aligned to at least that boundary. If not specified, or if zero, the target can
2795choose to align the allocation on any convenient boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2796
2797<p>'<tt>type</tt>' must be a sized type.</p>
2798
2799<h5>Semantics:</h5>
2800
2801<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2802a pointer is returned. The result of a zero byte allocattion is undefined. The
2803result is null if there is insufficient memory available.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2804
2805<h5>Example:</h5>
2806
2807<pre>
2808 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
2809
2810 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2811 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2812 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2813 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2814 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
2815</pre>
2816</div>
2817
2818<!-- _______________________________________________________________________ -->
2819<div class="doc_subsubsection">
2820 <a name="i_free">'<tt>free</tt>' Instruction</a>
2821</div>
2822
2823<div class="doc_text">
2824
2825<h5>Syntax:</h5>
2826
2827<pre>
2828 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
2829</pre>
2830
2831<h5>Overview:</h5>
2832
2833<p>The '<tt>free</tt>' instruction returns memory back to the unused
2834memory heap to be reallocated in the future.</p>
2835
2836<h5>Arguments:</h5>
2837
2838<p>'<tt>value</tt>' shall be a pointer value that points to a value
2839that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2840instruction.</p>
2841
2842<h5>Semantics:</h5>
2843
2844<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2845after this instruction executes. If the pointer is null, the behavior is
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2846undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2847
2848<h5>Example:</h5>
2849
2850<pre>
2851 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2852 free [4 x i8]* %array
2853</pre>
2854</div>
2855
2856<!-- _______________________________________________________________________ -->
2857<div class="doc_subsubsection">
2858 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2859</div>
2860
2861<div class="doc_text">
2862
2863<h5>Syntax:</h5>
2864
2865<pre>
2866 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2867</pre>
2868
2869<h5>Overview:</h5>
2870
2871<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
2872currently executing function, to be automatically released when this function
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]2873returns to its caller. The object is always allocated in the generic address
2874space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2875
2876<h5>Arguments:</h5>
2877
2878<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
2879bytes of memory on the runtime stack, returning a pointer of the
Gabor Greif5082cf42008-02-09 22:24:34 +0000[diff] [blame]2880appropriate type to the program. If "NumElements" is specified, it is the
2881number of elements allocated, otherwise "NumElements" is defaulted to be one.
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2882If a constant alignment is specified, the value result of the allocation is guaranteed
Gabor Greif5082cf42008-02-09 22:24:34 +0000[diff] [blame]2883to be aligned to at least that boundary. If not specified, or if zero, the target
2884can choose to align the allocation on any convenient boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2885
2886<p>'<tt>type</tt>' may be any sized type.</p>
2887
2888<h5>Semantics:</h5>
2889
Chris Lattner8b094fc2008-04-19 21:01:16 +0000[diff] [blame^]2890<p>Memory is allocated; a pointer is returned. The operation is undefiend if
2891there is insufficient stack space for the allocation. '<tt>alloca</tt>'d
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2892memory is automatically released when the function returns. The '<tt>alloca</tt>'
2893instruction is commonly used to represent automatic variables that must
2894have an address available. When the function returns (either with the <tt><a
2895 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2896instructions), the memory is reclaimed. Allocating zero bytes
2897is legal, but the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2898
2899<h5>Example:</h5>
2900
2901<pre>
2902 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2903 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2904 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2905 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
2906</pre>
2907</div>
2908
2909<!-- _______________________________________________________________________ -->
2910<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2911Instruction</a> </div>
2912<div class="doc_text">
2913<h5>Syntax:</h5>
2914<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>
2915<h5>Overview:</h5>
2916<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
2917<h5>Arguments:</h5>
2918<p>The argument to the '<tt>load</tt>' instruction specifies the memory
2919address from which to load. The pointer must point to a <a
2920 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
2921marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
2922the number or order of execution of this <tt>load</tt> with other
2923volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2924instructions. </p>
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2925<p>
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2926The optional constant "align" argument specifies the alignment of the operation
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2927(that is, the alignment of the memory address). A value of 0 or an
2928omitted "align" argument means that the operation has the preferential
2929alignment for the target. It is the responsibility of the code emitter
2930to ensure that the alignment information is correct. Overestimating
2931the alignment results in an undefined behavior. Underestimating the
2932alignment may produce less efficient code. An alignment of 1 is always
2933safe.
2934</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2935<h5>Semantics:</h5>
2936<p>The location of memory pointed to is loaded.</p>
2937<h5>Examples:</h5>
2938<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
2939 <a
2940 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2941 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
2942</pre>
2943</div>
2944<!-- _______________________________________________________________________ -->
2945<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2946Instruction</a> </div>
2947<div class="doc_text">
2948<h5>Syntax:</h5>
2949<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2950 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2951</pre>
2952<h5>Overview:</h5>
2953<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
2954<h5>Arguments:</h5>
2955<p>There are two arguments to the '<tt>store</tt>' instruction: a value
2956to store and an address at which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2957operand must be a pointer to the <a href="#t_firstclass">first class</a> type
2958of the '<tt>&lt;value&gt;</tt>'
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2959operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
2960optimizer is not allowed to modify the number or order of execution of
2961this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2962 href="#i_store">store</a></tt> instructions.</p>
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2963<p>
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]2964The optional constant "align" argument specifies the alignment of the operation
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2965(that is, the alignment of the memory address). A value of 0 or an
2966omitted "align" argument means that the operation has the preferential
2967alignment for the target. It is the responsibility of the code emitter
2968to ensure that the alignment information is correct. Overestimating
2969the alignment results in an undefined behavior. Underestimating the
2970alignment may produce less efficient code. An alignment of 1 is always
2971safe.
2972</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2973<h5>Semantics:</h5>
2974<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2975at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
2976<h5>Example:</h5>
2977<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Bill Wendling63ffa142007-10-22 05:10:05 +0000[diff] [blame]2978 store i32 3, i32* %ptr <i>; yields {void}</i>
2979 %val = <a href="#i_load">load</a> i32* %ptr <i>; yields {i32}:val = i32 3</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2980</pre>
2981</div>
2982
2983<!-- _______________________________________________________________________ -->
2984<div class="doc_subsubsection">
2985 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2986</div>
2987
2988<div class="doc_text">
2989<h5>Syntax:</h5>
2990<pre>
2991 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2992</pre>
2993
2994<h5>Overview:</h5>
2995
2996<p>
2997The '<tt>getelementptr</tt>' instruction is used to get the address of a
2998subelement of an aggregate data structure.</p>
2999
3000<h5>Arguments:</h5>
3001
3002<p>This instruction takes a list of integer operands that indicate what
3003elements of the aggregate object to index to. The actual types of the arguments
3004provided depend on the type of the first pointer argument. The
3005'<tt>getelementptr</tt>' instruction is used to index down through the type
3006levels of a structure or to a specific index in an array. When indexing into a
3007structure, only <tt>i32</tt> integer constants are allowed. When indexing
3008into an array or pointer, only integers of 32 or 64 bits are allowed, and will
3009be sign extended to 64-bit values.</p>
3010
3011<p>For example, let's consider a C code fragment and how it gets
3012compiled to LLVM:</p>
3013
3014<div class="doc_code">
3015<pre>
3016struct RT {
3017 char A;
3018 int B[10][20];
3019 char C;
3020};
3021struct ST {
3022 int X;
3023 double Y;
3024 struct RT Z;
3025};
3026
3027int *foo(struct ST *s) {
3028 return &amp;s[1].Z.B[5][13];
3029}
3030</pre>
3031</div>
3032
3033<p>The LLVM code generated by the GCC frontend is:</p>
3034
3035<div class="doc_code">
3036<pre>
3037%RT = type { i8 , [10 x [20 x i32]], i8 }
3038%ST = type { i32, double, %RT }
3039
3040define i32* %foo(%ST* %s) {
3041entry:
3042 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
3043 ret i32* %reg
3044}
3045</pre>
3046</div>
3047
3048<h5>Semantics:</h5>
3049
3050<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
3051on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
3052and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
3053<a href="#t_integer">integer</a> type but the value will always be sign extended
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]3054to 64-bits. <a href="#t_struct">Structure</a> and <a href="#t_pstruct">packed
3055structure</a> types require <tt>i32</tt> <b>constants</b>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3056
3057<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
3058type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
3059}</tt>' type, a structure. The second index indexes into the third element of
3060the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
3061i8 }</tt>' type, another structure. The third index indexes into the second
3062element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
3063array. The two dimensions of the array are subscripted into, yielding an
3064'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
3065to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
3066
3067<p>Note that it is perfectly legal to index partially through a
3068structure, returning a pointer to an inner element. Because of this,
3069the LLVM code for the given testcase is equivalent to:</p>
3070
3071<pre>
3072 define i32* %foo(%ST* %s) {
3073 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
3074 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
3075 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
3076 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
3077 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
3078 ret i32* %t5
3079 }
3080</pre>
3081
3082<p>Note that it is undefined to access an array out of bounds: array and
3083pointer indexes must always be within the defined bounds of the array type.
3084The one exception for this rules is zero length arrays. These arrays are
3085defined to be accessible as variable length arrays, which requires access
3086beyond the zero'th element.</p>
3087
3088<p>The getelementptr instruction is often confusing. For some more insight
3089into how it works, see <a href="GetElementPtr.html">the getelementptr
3090FAQ</a>.</p>
3091
3092<h5>Example:</h5>
3093
3094<pre>
3095 <i>; yields [12 x i8]*:aptr</i>
3096 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
3097</pre>
3098</div>
3099
3100<!-- ======================================================================= -->
3101<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
3102</div>
3103<div class="doc_text">
3104<p>The instructions in this category are the conversion instructions (casting)
3105which all take a single operand and a type. They perform various bit conversions
3106on the operand.</p>
3107</div>
3108
3109<!-- _______________________________________________________________________ -->
3110<div class="doc_subsubsection">
3111 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
3112</div>
3113<div class="doc_text">
3114
3115<h5>Syntax:</h5>
3116<pre>
3117 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3118</pre>
3119
3120<h5>Overview:</h5>
3121<p>
3122The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
3123</p>
3124
3125<h5>Arguments:</h5>
3126<p>
3127The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
3128be an <a href="#t_integer">integer</a> type, and a type that specifies the size
3129and type of the result, which must be an <a href="#t_integer">integer</a>
3130type. The bit size of <tt>value</tt> must be larger than the bit size of
3131<tt>ty2</tt>. Equal sized types are not allowed.</p>
3132
3133<h5>Semantics:</h5>
3134<p>
3135The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
3136and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
3137larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
3138It will always truncate bits.</p>
3139
3140<h5>Example:</h5>
3141<pre>
3142 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
3143 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
3144 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
3145</pre>
3146</div>
3147
3148<!-- _______________________________________________________________________ -->
3149<div class="doc_subsubsection">
3150 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3151</div>
3152<div class="doc_text">
3153
3154<h5>Syntax:</h5>
3155<pre>
3156 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3157</pre>
3158
3159<h5>Overview:</h5>
3160<p>The '<tt>zext</tt>' instruction zero extends its operand to type
3161<tt>ty2</tt>.</p>
3162
3163
3164<h5>Arguments:</h5>
3165<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3166<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3167also be of <a href="#t_integer">integer</a> type. The bit size of the
3168<tt>value</tt> must be smaller than the bit size of the destination type,
3169<tt>ty2</tt>.</p>
3170
3171<h5>Semantics:</h5>
3172<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3173bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3174
3175<p>When zero extending from i1, the result will always be either 0 or 1.</p>
3176
3177<h5>Example:</h5>
3178<pre>
3179 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3180 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3181</pre>
3182</div>
3183
3184<!-- _______________________________________________________________________ -->
3185<div class="doc_subsubsection">
3186 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3187</div>
3188<div class="doc_text">
3189
3190<h5>Syntax:</h5>
3191<pre>
3192 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3193</pre>
3194
3195<h5>Overview:</h5>
3196<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3197
3198<h5>Arguments:</h5>
3199<p>
3200The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3201<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3202also be of <a href="#t_integer">integer</a> type. The bit size of the
3203<tt>value</tt> must be smaller than the bit size of the destination type,
3204<tt>ty2</tt>.</p>
3205
3206<h5>Semantics:</h5>
3207<p>
3208The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3209bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3210the type <tt>ty2</tt>.</p>
3211
3212<p>When sign extending from i1, the extension always results in -1 or 0.</p>
3213
3214<h5>Example:</h5>
3215<pre>
3216 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3217 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3218</pre>
3219</div>
3220
3221<!-- _______________________________________________________________________ -->
3222<div class="doc_subsubsection">
3223 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3224</div>
3225
3226<div class="doc_text">
3227
3228<h5>Syntax:</h5>
3229
3230<pre>
3231 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3232</pre>
3233
3234<h5>Overview:</h5>
3235<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
3236<tt>ty2</tt>.</p>
3237
3238
3239<h5>Arguments:</h5>
3240<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
3241 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
3242cast it to. The size of <tt>value</tt> must be larger than the size of
3243<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
3244<i>no-op cast</i>.</p>
3245
3246<h5>Semantics:</h5>
3247<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
3248<a href="#t_floating">floating point</a> type to a smaller
3249<a href="#t_floating">floating point</a> type. If the value cannot fit within
3250the destination type, <tt>ty2</tt>, then the results are undefined.</p>
3251
3252<h5>Example:</h5>
3253<pre>
3254 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
3255 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
3256</pre>
3257</div>
3258
3259<!-- _______________________________________________________________________ -->
3260<div class="doc_subsubsection">
3261 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
3262</div>
3263<div class="doc_text">
3264
3265<h5>Syntax:</h5>
3266<pre>
3267 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3268</pre>
3269
3270<h5>Overview:</h5>
3271<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
3272floating point value.</p>
3273
3274<h5>Arguments:</h5>
3275<p>The '<tt>fpext</tt>' instruction takes a
3276<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
3277and a <a href="#t_floating">floating point</a> type to cast it to. The source
3278type must be smaller than the destination type.</p>
3279
3280<h5>Semantics:</h5>
3281<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
3282<a href="#t_floating">floating point</a> type to a larger
3283<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
3284used to make a <i>no-op cast</i> because it always changes bits. Use
3285<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
3286
3287<h5>Example:</h5>
3288<pre>
3289 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
3290 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
3291</pre>
3292</div>
3293
3294<!-- _______________________________________________________________________ -->
3295<div class="doc_subsubsection">
3296 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
3297</div>
3298<div class="doc_text">
3299
3300<h5>Syntax:</h5>
3301<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3302 &lt;result&gt; = fptoui &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3303</pre>
3304
3305<h5>Overview:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3306<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3307unsigned integer equivalent of type <tt>ty2</tt>.
3308</p>
3309
3310<h5>Arguments:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3311<p>The '<tt>fptoui</tt>' instruction takes a value to cast, which must be a
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3312scalar or vector <a href="#t_floating">floating point</a> value, and a type
3313to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3314type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3315vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3316
3317<h5>Semantics:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3318<p> The '<tt>fptoui</tt>' instruction converts its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3319<a href="#t_floating">floating point</a> operand into the nearest (rounding
3320towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3321the results are undefined.</p>
3322
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3323<h5>Example:</h5>
3324<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3325 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3326 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3327 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3328</pre>
3329</div>
3330
3331<!-- _______________________________________________________________________ -->
3332<div class="doc_subsubsection">
3333 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
3334</div>
3335<div class="doc_text">
3336
3337<h5>Syntax:</h5>
3338<pre>
3339 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3340</pre>
3341
3342<h5>Overview:</h5>
3343<p>The '<tt>fptosi</tt>' instruction converts
3344<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
3345</p>
3346
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3347<h5>Arguments:</h5>
3348<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3349scalar or vector <a href="#t_floating">floating point</a> value, and a type
3350to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3351type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3352vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3353
3354<h5>Semantics:</h5>
3355<p>The '<tt>fptosi</tt>' instruction converts its
3356<a href="#t_floating">floating point</a> operand into the nearest (rounding
3357towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3358the results are undefined.</p>
3359
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3360<h5>Example:</h5>
3361<pre>
3362 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3363 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3364 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
3365</pre>
3366</div>
3367
3368<!-- _______________________________________________________________________ -->
3369<div class="doc_subsubsection">
3370 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
3371</div>
3372<div class="doc_text">
3373
3374<h5>Syntax:</h5>
3375<pre>
3376 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3377</pre>
3378
3379<h5>Overview:</h5>
3380<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
3381integer and converts that value to the <tt>ty2</tt> type.</p>
3382
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3383<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3384<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
3385scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3386to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3387type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3388floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3389
3390<h5>Semantics:</h5>
3391<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
3392integer quantity and converts it to the corresponding floating point value. If
3393the value cannot fit in the floating point value, the results are undefined.</p>
3394
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3395<h5>Example:</h5>
3396<pre>
3397 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3398 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
3399</pre>
3400</div>
3401
3402<!-- _______________________________________________________________________ -->
3403<div class="doc_subsubsection">
3404 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
3405</div>
3406<div class="doc_text">
3407
3408<h5>Syntax:</h5>
3409<pre>
3410 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3411</pre>
3412
3413<h5>Overview:</h5>
3414<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
3415integer and converts that value to the <tt>ty2</tt> type.</p>
3416
3417<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3418<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
3419scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3420to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3421type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3422floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3423
3424<h5>Semantics:</h5>
3425<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
3426integer quantity and converts it to the corresponding floating point value. If
3427the value cannot fit in the floating point value, the results are undefined.</p>
3428
3429<h5>Example:</h5>
3430<pre>
3431 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3432 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
3433</pre>
3434</div>
3435
3436<!-- _______________________________________________________________________ -->
3437<div class="doc_subsubsection">
3438 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3439</div>
3440<div class="doc_text">
3441
3442<h5>Syntax:</h5>
3443<pre>
3444 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3445</pre>
3446
3447<h5>Overview:</h5>
3448<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3449the integer type <tt>ty2</tt>.</p>
3450
3451<h5>Arguments:</h5>
3452<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3453must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
3454<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3455
3456<h5>Semantics:</h5>
3457<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3458<tt>ty2</tt> by interpreting the pointer value as an integer and either
3459truncating or zero extending that value to the size of the integer type. If
3460<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3461<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3462are the same size, then nothing is done (<i>no-op cast</i>) other than a type
3463change.</p>
3464
3465<h5>Example:</h5>
3466<pre>
3467 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
3468 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
3469</pre>
3470</div>
3471
3472<!-- _______________________________________________________________________ -->
3473<div class="doc_subsubsection">
3474 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3475</div>
3476<div class="doc_text">
3477
3478<h5>Syntax:</h5>
3479<pre>
3480 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3481</pre>
3482
3483<h5>Overview:</h5>
3484<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3485a pointer type, <tt>ty2</tt>.</p>
3486
3487<h5>Arguments:</h5>
3488<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
3489value to cast, and a type to cast it to, which must be a
3490<a href="#t_pointer">pointer</a> type.
3491
3492<h5>Semantics:</h5>
3493<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3494<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3495the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3496size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3497the size of a pointer then a zero extension is done. If they are the same size,
3498nothing is done (<i>no-op cast</i>).</p>
3499
3500<h5>Example:</h5>
3501<pre>
3502 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
3503 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
3504 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
3505</pre>
3506</div>
3507
3508<!-- _______________________________________________________________________ -->
3509<div class="doc_subsubsection">
3510 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
3511</div>
3512<div class="doc_text">
3513
3514<h5>Syntax:</h5>
3515<pre>
3516 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3517</pre>
3518
3519<h5>Overview:</h5>
3520<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3521<tt>ty2</tt> without changing any bits.</p>
3522
3523<h5>Arguments:</h5>
3524<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
3525a first class value, and a type to cast it to, which must also be a <a
3526 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
3527and the destination type, <tt>ty2</tt>, must be identical. If the source
3528type is a pointer, the destination type must also be a pointer.</p>
3529
3530<h5>Semantics:</h5>
3531<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3532<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3533this conversion. The conversion is done as if the <tt>value</tt> had been
3534stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3535converted to other pointer types with this instruction. To convert pointers to
3536other types, use the <a href="#i_inttoptr">inttoptr</a> or
3537<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
3538
3539<h5>Example:</h5>
3540<pre>
3541 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3542 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3543 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
3544</pre>
3545</div>
3546
3547<!-- ======================================================================= -->
3548<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3549<div class="doc_text">
3550<p>The instructions in this category are the "miscellaneous"
3551instructions, which defy better classification.</p>
3552</div>
3553
3554<!-- _______________________________________________________________________ -->
3555<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3556</div>
3557<div class="doc_text">
3558<h5>Syntax:</h5>
3559<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3560</pre>
3561<h5>Overview:</h5>
3562<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]3563of its two integer or pointer operands.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3564<h5>Arguments:</h5>
3565<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3566the condition code indicating the kind of comparison to perform. It is not
3567a value, just a keyword. The possible condition code are:
3568<ol>
3569 <li><tt>eq</tt>: equal</li>
3570 <li><tt>ne</tt>: not equal </li>
3571 <li><tt>ugt</tt>: unsigned greater than</li>
3572 <li><tt>uge</tt>: unsigned greater or equal</li>
3573 <li><tt>ult</tt>: unsigned less than</li>
3574 <li><tt>ule</tt>: unsigned less or equal</li>
3575 <li><tt>sgt</tt>: signed greater than</li>
3576 <li><tt>sge</tt>: signed greater or equal</li>
3577 <li><tt>slt</tt>: signed less than</li>
3578 <li><tt>sle</tt>: signed less or equal</li>
3579</ol>
3580<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
3581<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
3582<h5>Semantics:</h5>
3583<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3584the condition code given as <tt>cond</tt>. The comparison performed always
3585yields a <a href="#t_primitive">i1</a> result, as follows:
3586<ol>
3587 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3588 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3589 </li>
3590 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3591 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3592 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3593 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3594 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3595 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3596 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3597 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3598 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3599 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3600 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3601 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3602 <li><tt>sge</tt>: interprets the operands as signed values and yields
3603 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3604 <li><tt>slt</tt>: interprets the operands as signed values and yields
3605 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3606 <li><tt>sle</tt>: interprets the operands as signed values and yields
3607 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3608</ol>
3609<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3610values are compared as if they were integers.</p>
3611
3612<h5>Example:</h5>
3613<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3614 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3615 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3616 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3617 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3618 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
3619</pre>
3620</div>
3621
3622<!-- _______________________________________________________________________ -->
3623<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3624</div>
3625<div class="doc_text">
3626<h5>Syntax:</h5>
3627<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3628</pre>
3629<h5>Overview:</h5>
3630<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3631of its floating point operands.</p>
3632<h5>Arguments:</h5>
3633<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3634the condition code indicating the kind of comparison to perform. It is not
3635a value, just a keyword. The possible condition code are:
3636<ol>
3637 <li><tt>false</tt>: no comparison, always returns false</li>
3638 <li><tt>oeq</tt>: ordered and equal</li>
3639 <li><tt>ogt</tt>: ordered and greater than </li>
3640 <li><tt>oge</tt>: ordered and greater than or equal</li>
3641 <li><tt>olt</tt>: ordered and less than </li>
3642 <li><tt>ole</tt>: ordered and less than or equal</li>
3643 <li><tt>one</tt>: ordered and not equal</li>
3644 <li><tt>ord</tt>: ordered (no nans)</li>
3645 <li><tt>ueq</tt>: unordered or equal</li>
3646 <li><tt>ugt</tt>: unordered or greater than </li>
3647 <li><tt>uge</tt>: unordered or greater than or equal</li>
3648 <li><tt>ult</tt>: unordered or less than </li>
3649 <li><tt>ule</tt>: unordered or less than or equal</li>
3650 <li><tt>une</tt>: unordered or not equal</li>
3651 <li><tt>uno</tt>: unordered (either nans)</li>
3652 <li><tt>true</tt>: no comparison, always returns true</li>
3653</ol>
3654<p><i>Ordered</i> means that neither operand is a QNAN while
3655<i>unordered</i> means that either operand may be a QNAN.</p>
3656<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3657<a href="#t_floating">floating point</a> typed. They must have identical
3658types.</p>
3659<h5>Semantics:</h5>
3660<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3661the condition code given as <tt>cond</tt>. The comparison performed always
3662yields a <a href="#t_primitive">i1</a> result, as follows:
3663<ol>
3664 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
3665 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3666 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3667 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3668 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
3669 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3670 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3671 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3672 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3673 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3674 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3675 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3676 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3677 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3678 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
3679 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3680 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
3681 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3682 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
3683 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3684 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
3685 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3686 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
3687 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3688 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
3689 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3690 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
3691 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3692</ol>
3693
3694<h5>Example:</h5>
3695<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3696 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3697 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3698 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3699</pre>
3700</div>
3701
3702<!-- _______________________________________________________________________ -->
3703<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3704Instruction</a> </div>
3705<div class="doc_text">
3706<h5>Syntax:</h5>
3707<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3708<h5>Overview:</h5>
3709<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3710the SSA graph representing the function.</p>
3711<h5>Arguments:</h5>
3712<p>The type of the incoming values is specified with the first type
3713field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3714as arguments, with one pair for each predecessor basic block of the
3715current block. Only values of <a href="#t_firstclass">first class</a>
3716type may be used as the value arguments to the PHI node. Only labels
3717may be used as the label arguments.</p>
3718<p>There must be no non-phi instructions between the start of a basic
3719block and the PHI instructions: i.e. PHI instructions must be first in
3720a basic block.</p>
3721<h5>Semantics:</h5>
3722<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
3723specified by the pair corresponding to the predecessor basic block that executed
3724just prior to the current block.</p>
3725<h5>Example:</h5>
3726<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>
3727</div>
3728
3729<!-- _______________________________________________________________________ -->
3730<div class="doc_subsubsection">
3731 <a name="i_select">'<tt>select</tt>' Instruction</a>
3732</div>
3733
3734<div class="doc_text">
3735
3736<h5>Syntax:</h5>
3737
3738<pre>
3739 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
3740</pre>
3741
3742<h5>Overview:</h5>
3743
3744<p>
3745The '<tt>select</tt>' instruction is used to choose one value based on a
3746condition, without branching.
3747</p>
3748
3749
3750<h5>Arguments:</h5>
3751
3752<p>
3753The '<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.
3754</p>
3755
3756<h5>Semantics:</h5>
3757
3758<p>
3759If the boolean condition evaluates to true, the instruction returns the first
3760value argument; otherwise, it returns the second value argument.
3761</p>
3762
3763<h5>Example:</h5>
3764
3765<pre>
3766 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
3767</pre>
3768</div>
3769
3770
3771<!-- _______________________________________________________________________ -->
3772<div class="doc_subsubsection">
3773 <a name="i_call">'<tt>call</tt>' Instruction</a>
3774</div>
3775
3776<div class="doc_text">
3777
3778<h5>Syntax:</h5>
3779<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3780 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt; [&lt;fnty&gt;*] &lt;fnptrval&gt;(&lt;param list&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3781</pre>
3782
3783<h5>Overview:</h5>
3784
3785<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
3786
3787<h5>Arguments:</h5>
3788
3789<p>This instruction requires several arguments:</p>
3790
3791<ol>
3792 <li>
3793 <p>The optional "tail" marker indicates whether the callee function accesses
3794 any allocas or varargs in the caller. If the "tail" marker is present, the
3795 function call is eligible for tail call optimization. Note that calls may
3796 be marked "tail" even if they do not occur before a <a
3797 href="#i_ret"><tt>ret</tt></a> instruction.
3798 </li>
3799 <li>
3800 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
3801 convention</a> the call should use. If none is specified, the call defaults
3802 to using C calling conventions.
3803 </li>
3804 <li>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3805 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
3806 the type of the return value. Functions that return no value are marked
3807 <tt><a href="#t_void">void</a></tt>.</p>
3808 </li>
3809 <li>
3810 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
3811 value being invoked. The argument types must match the types implied by
3812 this signature. This type can be omitted if the function is not varargs
3813 and if the function type does not return a pointer to a function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3814 </li>
3815 <li>
3816 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3817 be invoked. In most cases, this is a direct function invocation, but
3818 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
3819 to function value.</p>
3820 </li>
3821 <li>
3822 <p>'<tt>function args</tt>': argument list whose types match the
3823 function signature argument types. All arguments must be of
3824 <a href="#t_firstclass">first class</a> type. If the function signature
3825 indicates the function accepts a variable number of arguments, the extra
3826 arguments can be specified.</p>
3827 </li>
3828</ol>
3829
3830<h5>Semantics:</h5>
3831
3832<p>The '<tt>call</tt>' instruction is used to cause control flow to
3833transfer to a specified function, with its incoming arguments bound to
3834the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3835instruction in the called function, control flow continues with the
3836instruction after the function call, and the return value of the
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]3837function is bound to the result argument. If the callee returns multiple
3838values then the return values of the function are only accessible through
3839the '<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3840
3841<h5>Example:</h5>
3842
3843<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3844 %retval = call i32 @test(i32 %argc)
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]3845 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42) <i>; yields i32</i>
3846 %X = tail call i32 @foo() <i>; yields i32</i>
3847 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
3848 call void %foo(i8 97 signext)
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3849
3850 %struct.A = type { i32, i8 }
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]3851 %r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
3852 %gr = getresult %struct.A %r, 0 <i>; yields i32</i>
3853 %gr1 = getresult %struct.A %r, 1 <i>; yields i8</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3854</pre>
3855
3856</div>
3857
3858<!-- _______________________________________________________________________ -->
3859<div class="doc_subsubsection">
3860 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
3861</div>
3862
3863<div class="doc_text">
3864
3865<h5>Syntax:</h5>
3866
3867<pre>
3868 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
3869</pre>
3870
3871<h5>Overview:</h5>
3872
3873<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
3874the "variable argument" area of a function call. It is used to implement the
3875<tt>va_arg</tt> macro in C.</p>
3876
3877<h5>Arguments:</h5>
3878
3879<p>This instruction takes a <tt>va_list*</tt> value and the type of
3880the argument. It returns a value of the specified argument type and
3881increments the <tt>va_list</tt> to point to the next argument. The
3882actual type of <tt>va_list</tt> is target specific.</p>
3883
3884<h5>Semantics:</h5>
3885
3886<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3887type from the specified <tt>va_list</tt> and causes the
3888<tt>va_list</tt> to point to the next argument. For more information,
3889see the variable argument handling <a href="#int_varargs">Intrinsic
3890Functions</a>.</p>
3891
3892<p>It is legal for this instruction to be called in a function which does not
3893take a variable number of arguments, for example, the <tt>vfprintf</tt>
3894function.</p>
3895
3896<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
3897href="#intrinsics">intrinsic function</a> because it takes a type as an
3898argument.</p>
3899
3900<h5>Example:</h5>
3901
3902<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3903
3904</div>
3905
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3906<!-- _______________________________________________________________________ -->
3907<div class="doc_subsubsection">
3908 <a name="i_getresult">'<tt>getresult</tt>' Instruction</a>
3909</div>
3910
3911<div class="doc_text">
3912
3913<h5>Syntax:</h5>
3914<pre>
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3915 &lt;resultval&gt; = getresult &lt;type&gt; &lt;retval&gt;, &lt;index&gt;
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3916</pre>
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3917
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3918<h5>Overview:</h5>
3919
3920<p> The '<tt>getresult</tt>' instruction is used to extract individual values
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3921from a '<tt><a href="#i_call">call</a></tt>'
3922or '<tt><a href="#i_invoke">invoke</a></tt>' instruction that returns multiple
3923results.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3924
3925<h5>Arguments:</h5>
3926
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3927<p>The '<tt>getresult</tt>' instruction takes a call or invoke value as its
3928first argument. The value must have <a href="#t_struct">structure type</a>.
Chris Lattner10368b62008-04-02 00:38:26 +0000[diff] [blame]3929The second argument is a constant unsigned index value which must be in range for
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3930the number of values returned by the call.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3931
3932<h5>Semantics:</h5>
3933
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3934<p>The '<tt>getresult</tt>' instruction extracts the element identified by
3935'<tt>index</tt>' from the aggregate value.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3936
3937<h5>Example:</h5>
3938
3939<pre>
3940 %struct.A = type { i32, i8 }
3941
3942 %r = call %struct.A @foo()
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3943 %gr = getresult %struct.A %r, 0 <i>; yields i32:%gr</i>
3944 %gr1 = getresult %struct.A %r, 1 <i>; yields i8:%gr1</i>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3945 add i32 %gr, 42
3946 add i8 %gr1, 41
3947</pre>
3948
3949</div>
3950
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3951<!-- *********************************************************************** -->
3952<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3953<!-- *********************************************************************** -->
3954
3955<div class="doc_text">
3956
3957<p>LLVM supports the notion of an "intrinsic function". These functions have
3958well known names and semantics and are required to follow certain restrictions.
3959Overall, these intrinsics represent an extension mechanism for the LLVM
3960language that does not require changing all of the transformations in LLVM when
3961adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
3962
3963<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3964prefix is reserved in LLVM for intrinsic names; thus, function names may not
3965begin with this prefix. Intrinsic functions must always be external functions:
3966you cannot define the body of intrinsic functions. Intrinsic functions may
3967only be used in call or invoke instructions: it is illegal to take the address
3968of an intrinsic function. Additionally, because intrinsic functions are part
3969of the LLVM language, it is required if any are added that they be documented
3970here.</p>
3971
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3972<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
3973a family of functions that perform the same operation but on different data
3974types. Because LLVM can represent over 8 million different integer types,
3975overloading is used commonly to allow an intrinsic function to operate on any
3976integer type. One or more of the argument types or the result type can be
3977overloaded to accept any integer type. Argument types may also be defined as
3978exactly matching a previous argument's type or the result type. This allows an
3979intrinsic function which accepts multiple arguments, but needs all of them to
3980be of the same type, to only be overloaded with respect to a single argument or
3981the result.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3982
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3983<p>Overloaded intrinsics will have the names of its overloaded argument types
3984encoded into its function name, each preceded by a period. Only those types
3985which are overloaded result in a name suffix. Arguments whose type is matched
3986against another type do not. For example, the <tt>llvm.ctpop</tt> function can
3987take an integer of any width and returns an integer of exactly the same integer
3988width. This leads to a family of functions such as
3989<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
3990Only one type, the return type, is overloaded, and only one type suffix is
3991required. Because the argument's type is matched against the return type, it
3992does not require its own name suffix.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3993
3994<p>To learn how to add an intrinsic function, please see the
3995<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
3996</p>
3997
3998</div>
3999
4000<!-- ======================================================================= -->
4001<div class="doc_subsection">
4002 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
4003</div>
4004
4005<div class="doc_text">
4006
4007<p>Variable argument support is defined in LLVM with the <a
4008 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
4009intrinsic functions. These functions are related to the similarly
4010named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
4011
4012<p>All of these functions operate on arguments that use a
4013target-specific value type "<tt>va_list</tt>". The LLVM assembly
4014language reference manual does not define what this type is, so all
4015transformations should be prepared to handle these functions regardless of
4016the type used.</p>
4017
4018<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
4019instruction and the variable argument handling intrinsic functions are
4020used.</p>
4021
4022<div class="doc_code">
4023<pre>
4024define i32 @test(i32 %X, ...) {
4025 ; Initialize variable argument processing
4026 %ap = alloca i8*
4027 %ap2 = bitcast i8** %ap to i8*
4028 call void @llvm.va_start(i8* %ap2)
4029
4030 ; Read a single integer argument
4031 %tmp = va_arg i8** %ap, i32
4032
4033 ; Demonstrate usage of llvm.va_copy and llvm.va_end
4034 %aq = alloca i8*
4035 %aq2 = bitcast i8** %aq to i8*
4036 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
4037 call void @llvm.va_end(i8* %aq2)
4038
4039 ; Stop processing of arguments.
4040 call void @llvm.va_end(i8* %ap2)
4041 ret i32 %tmp
4042}
4043
4044declare void @llvm.va_start(i8*)
4045declare void @llvm.va_copy(i8*, i8*)
4046declare void @llvm.va_end(i8*)
4047</pre>
4048</div>
4049
4050</div>
4051
4052<!-- _______________________________________________________________________ -->
4053<div class="doc_subsubsection">
4054 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
4055</div>
4056
4057
4058<div class="doc_text">
4059<h5>Syntax:</h5>
4060<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
4061<h5>Overview:</h5>
4062<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
4063<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
4064href="#i_va_arg">va_arg</a></tt>.</p>
4065
4066<h5>Arguments:</h5>
4067
4068<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
4069
4070<h5>Semantics:</h5>
4071
4072<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
4073macro available in C. In a target-dependent way, it initializes the
4074<tt>va_list</tt> element to which the argument points, so that the next call to
4075<tt>va_arg</tt> will produce the first variable argument passed to the function.
4076Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
4077last argument of the function as the compiler can figure that out.</p>
4078
4079</div>
4080
4081<!-- _______________________________________________________________________ -->
4082<div class="doc_subsubsection">
4083 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
4084</div>
4085
4086<div class="doc_text">
4087<h5>Syntax:</h5>
4088<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
4089<h5>Overview:</h5>
4090
4091<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
4092which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
4093or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
4094
4095<h5>Arguments:</h5>
4096
4097<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
4098
4099<h5>Semantics:</h5>
4100
4101<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
4102macro available in C. In a target-dependent way, it destroys the
4103<tt>va_list</tt> element to which the argument points. Calls to <a
4104href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
4105<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
4106<tt>llvm.va_end</tt>.</p>
4107
4108</div>
4109
4110<!-- _______________________________________________________________________ -->
4111<div class="doc_subsubsection">
4112 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
4113</div>
4114
4115<div class="doc_text">
4116
4117<h5>Syntax:</h5>
4118
4119<pre>
4120 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
4121</pre>
4122
4123<h5>Overview:</h5>
4124
4125<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
4126from the source argument list to the destination argument list.</p>
4127
4128<h5>Arguments:</h5>
4129
4130<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
4131The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
4132
4133
4134<h5>Semantics:</h5>
4135
4136<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
4137macro available in C. In a target-dependent way, it copies the source
4138<tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
4139intrinsic is necessary because the <tt><a href="#int_va_start">
4140llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
4141example, memory allocation.</p>
4142
4143</div>
4144
4145<!-- ======================================================================= -->
4146<div class="doc_subsection">
4147 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
4148</div>
4149
4150<div class="doc_text">
4151
4152<p>
4153LLVM support for <a href="GarbageCollection.html">Accurate Garbage
4154Collection</a> requires the implementation and generation of these intrinsics.
4155These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
4156stack</a>, as well as garbage collector implementations that require <a
4157href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
4158Front-ends for type-safe garbage collected languages should generate these
4159intrinsics to make use of the LLVM garbage collectors. For more details, see <a
4160href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
4161</p>
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]4162
4163<p>The garbage collection intrinsics only operate on objects in the generic
4164 address space (address space zero).</p>
4165
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4166</div>
4167
4168<!-- _______________________________________________________________________ -->
4169<div class="doc_subsubsection">
4170 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
4171</div>
4172
4173<div class="doc_text">
4174
4175<h5>Syntax:</h5>
4176
4177<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4178 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4179</pre>
4180
4181<h5>Overview:</h5>
4182
4183<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
4184the code generator, and allows some metadata to be associated with it.</p>
4185
4186<h5>Arguments:</h5>
4187
4188<p>The first argument specifies the address of a stack object that contains the
4189root pointer. The second pointer (which must be either a constant or a global
4190value address) contains the meta-data to be associated with the root.</p>
4191
4192<h5>Semantics:</h5>
4193
4194<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
4195location. At compile-time, the code generator generates information to allow
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4196the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
4197intrinsic may only be used in a function which <a href="#gc">specifies a GC
4198algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4199
4200</div>
4201
4202
4203<!-- _______________________________________________________________________ -->
4204<div class="doc_subsubsection">
4205 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
4206</div>
4207
4208<div class="doc_text">
4209
4210<h5>Syntax:</h5>
4211
4212<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4213 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4214</pre>
4215
4216<h5>Overview:</h5>
4217
4218<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
4219locations, allowing garbage collector implementations that require read
4220barriers.</p>
4221
4222<h5>Arguments:</h5>
4223
4224<p>The second argument is the address to read from, which should be an address
4225allocated from the garbage collector. The first object is a pointer to the
4226start of the referenced object, if needed by the language runtime (otherwise
4227null).</p>
4228
4229<h5>Semantics:</h5>
4230
4231<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
4232instruction, but may be replaced with substantially more complex code by the
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4233garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
4234may only be used in a function which <a href="#gc">specifies a GC
4235algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4236
4237</div>
4238
4239
4240<!-- _______________________________________________________________________ -->
4241<div class="doc_subsubsection">
4242 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
4243</div>
4244
4245<div class="doc_text">
4246
4247<h5>Syntax:</h5>
4248
4249<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4250 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4251</pre>
4252
4253<h5>Overview:</h5>
4254
4255<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
4256locations, allowing garbage collector implementations that require write
4257barriers (such as generational or reference counting collectors).</p>
4258
4259<h5>Arguments:</h5>
4260
4261<p>The first argument is the reference to store, the second is the start of the
4262object to store it to, and the third is the address of the field of Obj to
4263store to. If the runtime does not require a pointer to the object, Obj may be
4264null.</p>
4265
4266<h5>Semantics:</h5>
4267
4268<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
4269instruction, but may be replaced with substantially more complex code by the
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4270garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
4271may only be used in a function which <a href="#gc">specifies a GC
4272algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4273
4274</div>
4275
4276
4277
4278<!-- ======================================================================= -->
4279<div class="doc_subsection">
4280 <a name="int_codegen">Code Generator Intrinsics</a>
4281</div>
4282
4283<div class="doc_text">
4284<p>
4285These intrinsics are provided by LLVM to expose special features that may only
4286be implemented with code generator support.
4287</p>
4288
4289</div>
4290
4291<!-- _______________________________________________________________________ -->
4292<div class="doc_subsubsection">
4293 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
4294</div>
4295
4296<div class="doc_text">
4297
4298<h5>Syntax:</h5>
4299<pre>
4300 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
4301</pre>
4302
4303<h5>Overview:</h5>
4304
4305<p>
4306The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
4307target-specific value indicating the return address of the current function
4308or one of its callers.
4309</p>
4310
4311<h5>Arguments:</h5>
4312
4313<p>
4314The argument to this intrinsic indicates which function to return the address
4315for. Zero indicates the calling function, one indicates its caller, etc. The
4316argument is <b>required</b> to be a constant integer value.
4317</p>
4318
4319<h5>Semantics:</h5>
4320
4321<p>
4322The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
4323the return address of the specified call frame, or zero if it cannot be
4324identified. The value returned by this intrinsic is likely to be incorrect or 0
4325for arguments other than zero, so it should only be used for debugging purposes.
4326</p>
4327
4328<p>
4329Note that calling this intrinsic does not prevent function inlining or other
4330aggressive transformations, so the value returned may not be that of the obvious
4331source-language caller.
4332</p>
4333</div>
4334
4335
4336<!-- _______________________________________________________________________ -->
4337<div class="doc_subsubsection">
4338 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
4339</div>
4340
4341<div class="doc_text">
4342
4343<h5>Syntax:</h5>
4344<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4345 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4346</pre>
4347
4348<h5>Overview:</h5>
4349
4350<p>
4351The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
4352target-specific frame pointer value for the specified stack frame.
4353</p>
4354
4355<h5>Arguments:</h5>
4356
4357<p>
4358The argument to this intrinsic indicates which function to return the frame
4359pointer for. Zero indicates the calling function, one indicates its caller,
4360etc. The argument is <b>required</b> to be a constant integer value.
4361</p>
4362
4363<h5>Semantics:</h5>
4364
4365<p>
4366The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
4367the frame address of the specified call frame, or zero if it cannot be
4368identified. The value returned by this intrinsic is likely to be incorrect or 0
4369for arguments other than zero, so it should only be used for debugging purposes.
4370</p>
4371
4372<p>
4373Note that calling this intrinsic does not prevent function inlining or other
4374aggressive transformations, so the value returned may not be that of the obvious
4375source-language caller.
4376</p>
4377</div>
4378
4379<!-- _______________________________________________________________________ -->
4380<div class="doc_subsubsection">
4381 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
4382</div>
4383
4384<div class="doc_text">
4385
4386<h5>Syntax:</h5>
4387<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4388 declare i8 *@llvm.stacksave()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4389</pre>
4390
4391<h5>Overview:</h5>
4392
4393<p>
4394The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
4395the function stack, for use with <a href="#int_stackrestore">
4396<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4397features like scoped automatic variable sized arrays in C99.
4398</p>
4399
4400<h5>Semantics:</h5>
4401
4402<p>
4403This intrinsic returns a opaque pointer value that can be passed to <a
4404href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
4405<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4406<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4407state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4408practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4409that were allocated after the <tt>llvm.stacksave</tt> was executed.
4410</p>
4411
4412</div>
4413
4414<!-- _______________________________________________________________________ -->
4415<div class="doc_subsubsection">
4416 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
4417</div>
4418
4419<div class="doc_text">
4420
4421<h5>Syntax:</h5>
4422<pre>
4423 declare void @llvm.stackrestore(i8 * %ptr)
4424</pre>
4425
4426<h5>Overview:</h5>
4427
4428<p>
4429The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4430the function stack to the state it was in when the corresponding <a
4431href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
4432useful for implementing language features like scoped automatic variable sized
4433arrays in C99.
4434</p>
4435
4436<h5>Semantics:</h5>
4437
4438<p>
4439See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
4440</p>
4441
4442</div>
4443
4444
4445<!-- _______________________________________________________________________ -->
4446<div class="doc_subsubsection">
4447 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
4448</div>
4449
4450<div class="doc_text">
4451
4452<h5>Syntax:</h5>
4453<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4454 declare void @llvm.prefetch(i8* &lt;address&gt;, i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4455</pre>
4456
4457<h5>Overview:</h5>
4458
4459
4460<p>
4461The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
4462a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4463no
4464effect on the behavior of the program but can change its performance
4465characteristics.
4466</p>
4467
4468<h5>Arguments:</h5>
4469
4470<p>
4471<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4472determining if the fetch should be for a read (0) or write (1), and
4473<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
4474locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
4475<tt>locality</tt> arguments must be constant integers.
4476</p>
4477
4478<h5>Semantics:</h5>
4479
4480<p>
4481This intrinsic does not modify the behavior of the program. In particular,
4482prefetches cannot trap and do not produce a value. On targets that support this
4483intrinsic, the prefetch can provide hints to the processor cache for better
4484performance.
4485</p>
4486
4487</div>
4488
4489<!-- _______________________________________________________________________ -->
4490<div class="doc_subsubsection">
4491 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4492</div>
4493
4494<div class="doc_text">
4495
4496<h5>Syntax:</h5>
4497<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4498 declare void @llvm.pcmarker(i32 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4499</pre>
4500
4501<h5>Overview:</h5>
4502
4503
4504<p>
4505The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4506(PC) in a region of
4507code to simulators and other tools. The method is target specific, but it is
4508expected that the marker will use exported symbols to transmit the PC of the marker.
4509The marker makes no guarantees that it will remain with any specific instruction
4510after optimizations. It is possible that the presence of a marker will inhibit
4511optimizations. The intended use is to be inserted after optimizations to allow
4512correlations of simulation runs.
4513</p>
4514
4515<h5>Arguments:</h5>
4516
4517<p>
4518<tt>id</tt> is a numerical id identifying the marker.
4519</p>
4520
4521<h5>Semantics:</h5>
4522
4523<p>
4524This intrinsic does not modify the behavior of the program. Backends that do not
4525support this intrinisic may ignore it.
4526</p>
4527
4528</div>
4529
4530<!-- _______________________________________________________________________ -->
4531<div class="doc_subsubsection">
4532 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4533</div>
4534
4535<div class="doc_text">
4536
4537<h5>Syntax:</h5>
4538<pre>
4539 declare i64 @llvm.readcyclecounter( )
4540</pre>
4541
4542<h5>Overview:</h5>
4543
4544
4545<p>
4546The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4547counter register (or similar low latency, high accuracy clocks) on those targets
4548that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4549As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4550should only be used for small timings.
4551</p>
4552
4553<h5>Semantics:</h5>
4554
4555<p>
4556When directly supported, reading the cycle counter should not modify any memory.
4557Implementations are allowed to either return a application specific value or a
4558system wide value. On backends without support, this is lowered to a constant 0.
4559</p>
4560
4561</div>
4562
4563<!-- ======================================================================= -->
4564<div class="doc_subsection">
4565 <a name="int_libc">Standard C Library Intrinsics</a>
4566</div>
4567
4568<div class="doc_text">
4569<p>
4570LLVM provides intrinsics for a few important standard C library functions.
4571These intrinsics allow source-language front-ends to pass information about the
4572alignment of the pointer arguments to the code generator, providing opportunity
4573for more efficient code generation.
4574</p>
4575
4576</div>
4577
4578<!-- _______________________________________________________________________ -->
4579<div class="doc_subsubsection">
4580 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4581</div>
4582
4583<div class="doc_text">
4584
4585<h5>Syntax:</h5>
4586<pre>
4587 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4588 i32 &lt;len&gt;, i32 &lt;align&gt;)
4589 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4590 i64 &lt;len&gt;, i32 &lt;align&gt;)
4591</pre>
4592
4593<h5>Overview:</h5>
4594
4595<p>
4596The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4597location to the destination location.
4598</p>
4599
4600<p>
4601Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4602intrinsics do not return a value, and takes an extra alignment argument.
4603</p>
4604
4605<h5>Arguments:</h5>
4606
4607<p>
4608The first argument is a pointer to the destination, the second is a pointer to
4609the source. The third argument is an integer argument
4610specifying the number of bytes to copy, and the fourth argument is the alignment
4611of the source and destination locations.
4612</p>
4613
4614<p>
4615If the call to this intrinisic has an alignment value that is not 0 or 1, then
4616the caller guarantees that both the source and destination pointers are aligned
4617to that boundary.
4618</p>
4619
4620<h5>Semantics:</h5>
4621
4622<p>
4623The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4624location to the destination location, which are not allowed to overlap. It
4625copies "len" bytes of memory over. If the argument is known to be aligned to
4626some boundary, this can be specified as the fourth argument, otherwise it should
4627be set to 0 or 1.
4628</p>
4629</div>
4630
4631
4632<!-- _______________________________________________________________________ -->
4633<div class="doc_subsubsection">
4634 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4635</div>
4636
4637<div class="doc_text">
4638
4639<h5>Syntax:</h5>
4640<pre>
4641 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4642 i32 &lt;len&gt;, i32 &lt;align&gt;)
4643 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4644 i64 &lt;len&gt;, i32 &lt;align&gt;)
4645</pre>
4646
4647<h5>Overview:</h5>
4648
4649<p>
4650The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4651location to the destination location. It is similar to the
Chris Lattnerdba16ea2008-01-06 19:51:52 +0000[diff] [blame]4652'<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to overlap.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4653</p>
4654
4655<p>
4656Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4657intrinsics do not return a value, and takes an extra alignment argument.
4658</p>
4659
4660<h5>Arguments:</h5>
4661
4662<p>
4663The first argument is a pointer to the destination, the second is a pointer to
4664the source. The third argument is an integer argument
4665specifying the number of bytes to copy, and the fourth argument is the alignment
4666of the source and destination locations.
4667</p>
4668
4669<p>
4670If the call to this intrinisic has an alignment value that is not 0 or 1, then
4671the caller guarantees that the source and destination pointers are aligned to
4672that boundary.
4673</p>
4674
4675<h5>Semantics:</h5>
4676
4677<p>
4678The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
4679location to the destination location, which may overlap. It
4680copies "len" bytes of memory over. If the argument is known to be aligned to
4681some boundary, this can be specified as the fourth argument, otherwise it should
4682be set to 0 or 1.
4683</p>
4684</div>
4685
4686
4687<!-- _______________________________________________________________________ -->
4688<div class="doc_subsubsection">
4689 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
4690</div>
4691
4692<div class="doc_text">
4693
4694<h5>Syntax:</h5>
4695<pre>
4696 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4697 i32 &lt;len&gt;, i32 &lt;align&gt;)
4698 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4699 i64 &lt;len&gt;, i32 &lt;align&gt;)
4700</pre>
4701
4702<h5>Overview:</h5>
4703
4704<p>
4705The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
4706byte value.
4707</p>
4708
4709<p>
4710Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4711does not return a value, and takes an extra alignment argument.
4712</p>
4713
4714<h5>Arguments:</h5>
4715
4716<p>
4717The first argument is a pointer to the destination to fill, the second is the
4718byte value to fill it with, the third argument is an integer
4719argument specifying the number of bytes to fill, and the fourth argument is the
4720known alignment of destination location.
4721</p>
4722
4723<p>
4724If the call to this intrinisic has an alignment value that is not 0 or 1, then
4725the caller guarantees that the destination pointer is aligned to that boundary.
4726</p>
4727
4728<h5>Semantics:</h5>
4729
4730<p>
4731The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4732the
4733destination location. If the argument is known to be aligned to some boundary,
4734this can be specified as the fourth argument, otherwise it should be set to 0 or
47351.
4736</p>
4737</div>
4738
4739
4740<!-- _______________________________________________________________________ -->
4741<div class="doc_subsubsection">
4742 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
4743</div>
4744
4745<div class="doc_text">
4746
4747<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4748<p>This is an overloaded intrinsic. You can use <tt>llvm.sqrt</tt> on any
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4749floating point or vector of floating point type. Not all targets support all
4750types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4751<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4752 declare float @llvm.sqrt.f32(float %Val)
4753 declare double @llvm.sqrt.f64(double %Val)
4754 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
4755 declare fp128 @llvm.sqrt.f128(fp128 %Val)
4756 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4757</pre>
4758
4759<h5>Overview:</h5>
4760
4761<p>
4762The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4763returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4764<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
Chris Lattnerf914a002008-01-29 07:00:44 +0000[diff] [blame]4765negative numbers other than -0.0 (which allows for better optimization, because
4766there is no need to worry about errno being set). <tt>llvm.sqrt(-0.0)</tt> is
4767defined to return -0.0 like IEEE sqrt.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4768</p>
4769
4770<h5>Arguments:</h5>
4771
4772<p>
4773The argument and return value are floating point numbers of the same type.
4774</p>
4775
4776<h5>Semantics:</h5>
4777
4778<p>
4779This function returns the sqrt of the specified operand if it is a nonnegative
4780floating point number.
4781</p>
4782</div>
4783
4784<!-- _______________________________________________________________________ -->
4785<div class="doc_subsubsection">
4786 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4787</div>
4788
4789<div class="doc_text">
4790
4791<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4792<p>This is an overloaded intrinsic. You can use <tt>llvm.powi</tt> on any
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4793floating point or vector of floating point type. Not all targets support all
4794types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4795<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4796 declare float @llvm.powi.f32(float %Val, i32 %power)
4797 declare double @llvm.powi.f64(double %Val, i32 %power)
4798 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
4799 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
4800 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4801</pre>
4802
4803<h5>Overview:</h5>
4804
4805<p>
4806The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4807specified (positive or negative) power. The order of evaluation of
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4808multiplications is not defined. When a vector of floating point type is
4809used, the second argument remains a scalar integer value.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4810</p>
4811
4812<h5>Arguments:</h5>
4813
4814<p>
4815The second argument is an integer power, and the first is a value to raise to
4816that power.
4817</p>
4818
4819<h5>Semantics:</h5>
4820
4821<p>
4822This function returns the first value raised to the second power with an
4823unspecified sequence of rounding operations.</p>
4824</div>
4825
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4826<!-- _______________________________________________________________________ -->
4827<div class="doc_subsubsection">
4828 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
4829</div>
4830
4831<div class="doc_text">
4832
4833<h5>Syntax:</h5>
4834<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
4835floating point or vector of floating point type. Not all targets support all
4836types however.
4837<pre>
4838 declare float @llvm.sin.f32(float %Val)
4839 declare double @llvm.sin.f64(double %Val)
4840 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
4841 declare fp128 @llvm.sin.f128(fp128 %Val)
4842 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
4843</pre>
4844
4845<h5>Overview:</h5>
4846
4847<p>
4848The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
4849</p>
4850
4851<h5>Arguments:</h5>
4852
4853<p>
4854The argument and return value are floating point numbers of the same type.
4855</p>
4856
4857<h5>Semantics:</h5>
4858
4859<p>
4860This function returns the sine of the specified operand, returning the
4861same values as the libm <tt>sin</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4862conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4863</div>
4864
4865<!-- _______________________________________________________________________ -->
4866<div class="doc_subsubsection">
4867 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
4868</div>
4869
4870<div class="doc_text">
4871
4872<h5>Syntax:</h5>
4873<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
4874floating point or vector of floating point type. Not all targets support all
4875types however.
4876<pre>
4877 declare float @llvm.cos.f32(float %Val)
4878 declare double @llvm.cos.f64(double %Val)
4879 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
4880 declare fp128 @llvm.cos.f128(fp128 %Val)
4881 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
4882</pre>
4883
4884<h5>Overview:</h5>
4885
4886<p>
4887The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
4888</p>
4889
4890<h5>Arguments:</h5>
4891
4892<p>
4893The argument and return value are floating point numbers of the same type.
4894</p>
4895
4896<h5>Semantics:</h5>
4897
4898<p>
4899This function returns the cosine of the specified operand, returning the
4900same values as the libm <tt>cos</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4901conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4902</div>
4903
4904<!-- _______________________________________________________________________ -->
4905<div class="doc_subsubsection">
4906 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
4907</div>
4908
4909<div class="doc_text">
4910
4911<h5>Syntax:</h5>
4912<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
4913floating point or vector of floating point type. Not all targets support all
4914types however.
4915<pre>
4916 declare float @llvm.pow.f32(float %Val, float %Power)
4917 declare double @llvm.pow.f64(double %Val, double %Power)
4918 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
4919 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
4920 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
4921</pre>
4922
4923<h5>Overview:</h5>
4924
4925<p>
4926The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
4927specified (positive or negative) power.
4928</p>
4929
4930<h5>Arguments:</h5>
4931
4932<p>
4933The second argument is a floating point power, and the first is a value to
4934raise to that power.
4935</p>
4936
4937<h5>Semantics:</h5>
4938
4939<p>
4940This function returns the first value raised to the second power,
4941returning the
4942same values as the libm <tt>pow</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4943conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4944</div>
4945
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4946
4947<!-- ======================================================================= -->
4948<div class="doc_subsection">
4949 <a name="int_manip">Bit Manipulation Intrinsics</a>
4950</div>
4951
4952<div class="doc_text">
4953<p>
4954LLVM provides intrinsics for a few important bit manipulation operations.
4955These allow efficient code generation for some algorithms.
4956</p>
4957
4958</div>
4959
4960<!-- _______________________________________________________________________ -->
4961<div class="doc_subsubsection">
4962 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4963</div>
4964
4965<div class="doc_text">
4966
4967<h5>Syntax:</h5>
4968<p>This is an overloaded intrinsic function. You can use bswap on any integer
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4969type that is an even number of bytes (i.e. BitWidth % 16 == 0).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4970<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4971 declare i16 @llvm.bswap.i16(i16 &lt;id&gt;)
4972 declare i32 @llvm.bswap.i32(i32 &lt;id&gt;)
4973 declare i64 @llvm.bswap.i64(i64 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4974</pre>
4975
4976<h5>Overview:</h5>
4977
4978<p>
4979The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
4980values with an even number of bytes (positive multiple of 16 bits). These are
4981useful for performing operations on data that is not in the target's native
4982byte order.
4983</p>
4984
4985<h5>Semantics:</h5>
4986
4987<p>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4988The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4989and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4990intrinsic returns an i32 value that has the four bytes of the input i32
4991swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4992i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
4993<tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4994additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
4995</p>
4996
4997</div>
4998
4999<!-- _______________________________________________________________________ -->
5000<div class="doc_subsubsection">
5001 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
5002</div>
5003
5004<div class="doc_text">
5005
5006<h5>Syntax:</h5>
5007<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
5008width. Not all targets support all bit widths however.
5009<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5010 declare i8 @llvm.ctpop.i8 (i8 &lt;src&gt;)
5011 declare i16 @llvm.ctpop.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5012 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5013 declare i64 @llvm.ctpop.i64(i64 &lt;src&gt;)
5014 declare i256 @llvm.ctpop.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5015</pre>
5016
5017<h5>Overview:</h5>
5018
5019<p>
5020The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
5021value.
5022</p>
5023
5024<h5>Arguments:</h5>
5025
5026<p>
5027The only argument is the value to be counted. The argument may be of any
5028integer type. The return type must match the argument type.
5029</p>
5030
5031<h5>Semantics:</h5>
5032
5033<p>
5034The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
5035</p>
5036</div>
5037
5038<!-- _______________________________________________________________________ -->
5039<div class="doc_subsubsection">
5040 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
5041</div>
5042
5043<div class="doc_text">
5044
5045<h5>Syntax:</h5>
5046<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
5047integer bit width. Not all targets support all bit widths however.
5048<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5049 declare i8 @llvm.ctlz.i8 (i8 &lt;src&gt;)
5050 declare i16 @llvm.ctlz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5051 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5052 declare i64 @llvm.ctlz.i64(i64 &lt;src&gt;)
5053 declare i256 @llvm.ctlz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5054</pre>
5055
5056<h5>Overview:</h5>
5057
5058<p>
5059The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
5060leading zeros in a variable.
5061</p>
5062
5063<h5>Arguments:</h5>
5064
5065<p>
5066The only argument is the value to be counted. The argument may be of any
5067integer type. The return type must match the argument type.
5068</p>
5069
5070<h5>Semantics:</h5>
5071
5072<p>
5073The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
5074in a variable. If the src == 0 then the result is the size in bits of the type
5075of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
5076</p>
5077</div>
5078
5079
5080
5081<!-- _______________________________________________________________________ -->
5082<div class="doc_subsubsection">
5083 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
5084</div>
5085
5086<div class="doc_text">
5087
5088<h5>Syntax:</h5>
5089<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
5090integer bit width. Not all targets support all bit widths however.
5091<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5092 declare i8 @llvm.cttz.i8 (i8 &lt;src&gt;)
5093 declare i16 @llvm.cttz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5094 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5095 declare i64 @llvm.cttz.i64(i64 &lt;src&gt;)
5096 declare i256 @llvm.cttz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5097</pre>
5098
5099<h5>Overview:</h5>
5100
5101<p>
5102The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
5103trailing zeros.
5104</p>
5105
5106<h5>Arguments:</h5>
5107
5108<p>
5109The only argument is the value to be counted. The argument may be of any
5110integer type. The return type must match the argument type.
5111</p>
5112
5113<h5>Semantics:</h5>
5114
5115<p>
5116The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
5117in a variable. If the src == 0 then the result is the size in bits of the type
5118of src. For example, <tt>llvm.cttz(2) = 1</tt>.
5119</p>
5120</div>
5121
5122<!-- _______________________________________________________________________ -->
5123<div class="doc_subsubsection">
5124 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
5125</div>
5126
5127<div class="doc_text">
5128
5129<h5>Syntax:</h5>
5130<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
5131on any integer bit width.
5132<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5133 declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
5134 declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5135</pre>
5136
5137<h5>Overview:</h5>
5138<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
5139range of bits from an integer value and returns them in the same bit width as
5140the original value.</p>
5141
5142<h5>Arguments:</h5>
5143<p>The first argument, <tt>%val</tt> and the result may be integer types of
5144any bit width but they must have the same bit width. The second and third
5145arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
5146
5147<h5>Semantics:</h5>
5148<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
5149of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
5150<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
5151operates in forward mode.</p>
5152<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
5153right by <tt>%loBit</tt> bits and then ANDing it with a mask with
5154only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
5155<ol>
5156 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
5157 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
5158 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
5159 to determine the number of bits to retain.</li>
5160 <li>A mask of the retained bits is created by shifting a -1 value.</li>
5161 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
5162</ol>
5163<p>In reverse mode, a similar computation is made except that the bits are
5164returned in the reverse order. So, for example, if <tt>X</tt> has the value
5165<tt>i16 0x0ACF (101011001111)</tt> and we apply
5166<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
5167<tt>i16 0x0026 (000000100110)</tt>.</p>
5168</div>
5169
5170<div class="doc_subsubsection">
5171 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
5172</div>
5173
5174<div class="doc_text">
5175
5176<h5>Syntax:</h5>
5177<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
5178on any integer bit width.
5179<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5180 declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
5181 declare i29 @llvm.part.set.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5182</pre>
5183
5184<h5>Overview:</h5>
5185<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
5186of bits in an integer value with another integer value. It returns the integer
5187with the replaced bits.</p>
5188
5189<h5>Arguments:</h5>
5190<p>The first argument, <tt>%val</tt> and the result may be integer types of
5191any bit width but they must have the same bit width. <tt>%val</tt> is the value
5192whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
5193integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
5194type since they specify only a bit index.</p>
5195
5196<h5>Semantics:</h5>
5197<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
5198of operation: forwards and reverse. If <tt>%lo</tt> is greater than
5199<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
5200operates in forward mode.</p>
5201<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
5202truncating it down to the size of the replacement area or zero extending it
5203up to that size.</p>
5204<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
5205are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
5206in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
5207to the <tt>%hi</tt>th bit.
5208<p>In reverse mode, a similar computation is made except that the bits are
5209reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
5210<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
5211<h5>Examples:</h5>
5212<pre>
5213 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
5214 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0xFF0F
5215 llvm.part.set(0xFFFF, 1, 7, 4) -&gt; 0xFF8F
5216 llvm.part.set(0xFFFF, F, 8, 3) -&gt; 0xFFE7
5217 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
5218</pre>
5219</div>
5220
5221<!-- ======================================================================= -->
5222<div class="doc_subsection">
5223 <a name="int_debugger">Debugger Intrinsics</a>
5224</div>
5225
5226<div class="doc_text">
5227<p>
5228The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
5229are described in the <a
5230href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
5231Debugging</a> document.
5232</p>
5233</div>
5234
5235
5236<!-- ======================================================================= -->
5237<div class="doc_subsection">
5238 <a name="int_eh">Exception Handling Intrinsics</a>
5239</div>
5240
5241<div class="doc_text">
5242<p> The LLVM exception handling intrinsics (which all start with
5243<tt>llvm.eh.</tt> prefix), are described in the <a
5244href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
5245Handling</a> document. </p>
5246</div>
5247
5248<!-- ======================================================================= -->
5249<div class="doc_subsection">
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5250 <a name="int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5251</div>
5252
5253<div class="doc_text">
5254<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5255 This intrinsic makes it possible to excise one parameter, marked with
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5256 the <tt>nest</tt> attribute, from a function. The result is a callable
5257 function pointer lacking the nest parameter - the caller does not need
5258 to provide a value for it. Instead, the value to use is stored in
5259 advance in a "trampoline", a block of memory usually allocated
5260 on the stack, which also contains code to splice the nest value into the
5261 argument list. This is used to implement the GCC nested function address
5262 extension.
5263</p>
5264<p>
5265 For example, if the function is
5266 <tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function
Bill Wendlinge262b4c2007-09-22 09:23:55 +0000[diff] [blame]5267 pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as follows:</p>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5268<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5269 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
5270 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
5271 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
5272 %fp = bitcast i8* %p to i32 (i32, i32)*
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5273</pre>
Bill Wendlinge262b4c2007-09-22 09:23:55 +0000[diff] [blame]5274 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
5275 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5276</div>
5277
5278<!-- _______________________________________________________________________ -->
5279<div class="doc_subsubsection">
5280 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
5281</div>
5282<div class="doc_text">
5283<h5>Syntax:</h5>
5284<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5285declare i8* @llvm.init.trampoline(i8* &lt;tramp&gt;, i8* &lt;func&gt;, i8* &lt;nval&gt;)
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5286</pre>
5287<h5>Overview:</h5>
5288<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5289 This fills the memory pointed to by <tt>tramp</tt> with code
5290 and returns a function pointer suitable for executing it.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5291</p>
5292<h5>Arguments:</h5>
5293<p>
5294 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
5295 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
5296 and sufficiently aligned block of memory; this memory is written to by the
Duncan Sands35012212007-08-22 23:39:54 +0000[diff] [blame]5297 intrinsic. Note that the size and the alignment are target-specific - LLVM
5298 currently provides no portable way of determining them, so a front-end that
5299 generates this intrinsic needs to have some target-specific knowledge.
5300 The <tt>func</tt> argument must hold a function bitcast to an <tt>i8*</tt>.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5301</p>
5302<h5>Semantics:</h5>
5303<p>
5304 The block of memory pointed to by <tt>tramp</tt> is filled with target
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5305 dependent code, turning it into a function. A pointer to this function is
5306 returned, but needs to be bitcast to an
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5307 <a href="#int_trampoline">appropriate function pointer type</a>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5308 before being called. The new function's signature is the same as that of
5309 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
5310 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
5311 of pointer type. Calling the new function is equivalent to calling
5312 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
5313 missing <tt>nest</tt> argument. If, after calling
5314 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
5315 modified, then the effect of any later call to the returned function pointer is
5316 undefined.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5317</p>
5318</div>
5319
5320<!-- ======================================================================= -->
5321<div class="doc_subsection">
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]5322 <a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
5323</div>
5324
5325<div class="doc_text">
5326<p>
5327 These intrinsic functions expand the "universal IR" of LLVM to represent
5328 hardware constructs for atomic operations and memory synchronization. This
5329 provides an interface to the hardware, not an interface to the programmer. It
5330 is aimed at a low enough level to allow any programming models or APIs which
5331 need atomic behaviors to map cleanly onto it. It is also modeled primarily on
5332 hardware behavior. Just as hardware provides a "universal IR" for source
5333 languages, it also provides a starting point for developing a "universal"
5334 atomic operation and synchronization IR.
5335</p>
5336<p>
5337 These do <em>not</em> form an API such as high-level threading libraries,
5338 software transaction memory systems, atomic primitives, and intrinsic
5339 functions as found in BSD, GNU libc, atomic_ops, APR, and other system and
5340 application libraries. The hardware interface provided by LLVM should allow
5341 a clean implementation of all of these APIs and parallel programming models.
5342 No one model or paradigm should be selected above others unless the hardware
5343 itself ubiquitously does so.
5344
5345</p>
5346</div>
5347
5348<!-- _______________________________________________________________________ -->
5349<div class="doc_subsubsection">
5350 <a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
5351</div>
5352<div class="doc_text">
5353<h5>Syntax:</h5>
5354<pre>
5355declare void @llvm.memory.barrier( i1 &lt;ll&gt;, i1 &lt;ls&gt;, i1 &lt;sl&gt;, i1 &lt;ss&gt;,
5356i1 &lt;device&gt; )
5357
5358</pre>
5359<h5>Overview:</h5>
5360<p>
5361 The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between
5362 specific pairs of memory access types.
5363</p>
5364<h5>Arguments:</h5>
5365<p>
5366 The <tt>llvm.memory.barrier</tt> intrinsic requires five boolean arguments.
5367 The first four arguments enables a specific barrier as listed below. The fith
5368 argument specifies that the barrier applies to io or device or uncached memory.
5369
5370</p>
5371 <ul>
5372 <li><tt>ll</tt>: load-load barrier</li>
5373 <li><tt>ls</tt>: load-store barrier</li>
5374 <li><tt>sl</tt>: store-load barrier</li>
5375 <li><tt>ss</tt>: store-store barrier</li>
5376 <li><tt>device</tt>: barrier applies to device and uncached memory also.
5377 </ul>
5378<h5>Semantics:</h5>
5379<p>
5380 This intrinsic causes the system to enforce some ordering constraints upon
5381 the loads and stores of the program. This barrier does not indicate
5382 <em>when</em> any events will occur, it only enforces an <em>order</em> in
5383 which they occur. For any of the specified pairs of load and store operations
5384 (f.ex. load-load, or store-load), all of the first operations preceding the
5385 barrier will complete before any of the second operations succeeding the
5386 barrier begin. Specifically the semantics for each pairing is as follows:
5387</p>
5388 <ul>
5389 <li><tt>ll</tt>: All loads before the barrier must complete before any load
5390 after the barrier begins.</li>
5391
5392 <li><tt>ls</tt>: All loads before the barrier must complete before any
5393 store after the barrier begins.</li>
5394 <li><tt>ss</tt>: All stores before the barrier must complete before any
5395 store after the barrier begins.</li>
5396 <li><tt>sl</tt>: All stores before the barrier must complete before any
5397 load after the barrier begins.</li>
5398 </ul>
5399<p>
5400 These semantics are applied with a logical "and" behavior when more than one
5401 is enabled in a single memory barrier intrinsic.
5402</p>
5403<p>
5404 Backends may implement stronger barriers than those requested when they do not
5405 support as fine grained a barrier as requested. Some architectures do not
5406 need all types of barriers and on such architectures, these become noops.
5407</p>
5408<h5>Example:</h5>
5409<pre>
5410%ptr = malloc i32
5411 store i32 4, %ptr
5412
5413%result1 = load i32* %ptr <i>; yields {i32}:result1 = 4</i>
5414 call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
5415 <i>; guarantee the above finishes</i>
5416 store i32 8, %ptr <i>; before this begins</i>
5417</pre>
5418</div>
5419
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]5420<!-- _______________________________________________________________________ -->
5421<div class="doc_subsubsection">
5422 <a name="int_atomic_lcs">'<tt>llvm.atomic.lcs.*</tt>' Intrinsic</a>
5423</div>
5424<div class="doc_text">
5425<h5>Syntax:</h5>
5426<p>
5427 This is an overloaded intrinsic. You can use <tt>llvm.atomic.lcs</tt> on any
5428 integer bit width. Not all targets support all bit widths however.</p>
5429
5430<pre>
5431declare i8 @llvm.atomic.lcs.i8( i8* &lt;ptr&gt;, i8 &lt;cmp&gt;, i8 &lt;val&gt; )
5432declare i16 @llvm.atomic.lcs.i16( i16* &lt;ptr&gt;, i16 &lt;cmp&gt;, i16 &lt;val&gt; )
5433declare i32 @llvm.atomic.lcs.i32( i32* &lt;ptr&gt;, i32 &lt;cmp&gt;, i32 &lt;val&gt; )
5434declare i64 @llvm.atomic.lcs.i64( i64* &lt;ptr&gt;, i64 &lt;cmp&gt;, i64 &lt;val&gt; )
5435
5436</pre>
5437<h5>Overview:</h5>
5438<p>
5439 This loads a value in memory and compares it to a given value. If they are
5440 equal, it stores a new value into the memory.
5441</p>
5442<h5>Arguments:</h5>
5443<p>
5444 The <tt>llvm.atomic.lcs</tt> intrinsic takes three arguments. The result as
5445 well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the
5446 same bit width. The <tt>ptr</tt> argument must be a pointer to a value of
5447 this integer type. While any bit width integer may be used, targets may only
5448 lower representations they support in hardware.
5449
5450</p>
5451<h5>Semantics:</h5>
5452<p>
5453 This entire intrinsic must be executed atomically. It first loads the value
5454 in memory pointed to by <tt>ptr</tt> and compares it with the value
5455 <tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the memory. The
5456 loaded value is yielded in all cases. This provides the equivalent of an
5457 atomic compare-and-swap operation within the SSA framework.
5458</p>
5459<h5>Examples:</h5>
5460
5461<pre>
5462%ptr = malloc i32
5463 store i32 4, %ptr
5464
5465%val1 = add i32 4, 4
5466%result1 = call i32 @llvm.atomic.lcs.i32( i32* %ptr, i32 4, %val1 )
5467 <i>; yields {i32}:result1 = 4</i>
5468%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
5469%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
5470
5471%val2 = add i32 1, 1
5472%result2 = call i32 @llvm.atomic.lcs.i32( i32* %ptr, i32 5, %val2 )
5473 <i>; yields {i32}:result2 = 8</i>
5474%stored2 = icmp eq i32 %result2, 5 <i>; yields {i1}:stored2 = false</i>
5475
5476%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 8</i>
5477</pre>
5478</div>
5479
5480<!-- _______________________________________________________________________ -->
5481<div class="doc_subsubsection">
5482 <a name="int_atomic_swap">'<tt>llvm.atomic.swap.*</tt>' Intrinsic</a>
5483</div>
5484<div class="doc_text">
5485<h5>Syntax:</h5>
5486
5487<p>
5488 This is an overloaded intrinsic. You can use <tt>llvm.atomic.swap</tt> on any
5489 integer bit width. Not all targets support all bit widths however.</p>
5490<pre>
5491declare i8 @llvm.atomic.swap.i8( i8* &lt;ptr&gt;, i8 &lt;val&gt; )
5492declare i16 @llvm.atomic.swap.i16( i16* &lt;ptr&gt;, i16 &lt;val&gt; )
5493declare i32 @llvm.atomic.swap.i32( i32* &lt;ptr&gt;, i32 &lt;val&gt; )
5494declare i64 @llvm.atomic.swap.i64( i64* &lt;ptr&gt;, i64 &lt;val&gt; )
5495
5496</pre>
5497<h5>Overview:</h5>
5498<p>
5499 This intrinsic loads the value stored in memory at <tt>ptr</tt> and yields
5500 the value from memory. It then stores the value in <tt>val</tt> in the memory
5501 at <tt>ptr</tt>.
5502</p>
5503<h5>Arguments:</h5>
5504
5505<p>
5506 The <tt>llvm.atomic.ls</tt> intrinsic takes two arguments. Both the
5507 <tt>val</tt> argument and the result must be integers of the same bit width.
5508 The first argument, <tt>ptr</tt>, must be a pointer to a value of this
5509 integer type. The targets may only lower integer representations they
5510 support.
5511</p>
5512<h5>Semantics:</h5>
5513<p>
5514 This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and
5515 stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the
5516 equivalent of an atomic swap operation within the SSA framework.
5517
5518</p>
5519<h5>Examples:</h5>
5520<pre>
5521%ptr = malloc i32
5522 store i32 4, %ptr
5523
5524%val1 = add i32 4, 4
5525%result1 = call i32 @llvm.atomic.swap.i32( i32* %ptr, i32 %val1 )
5526 <i>; yields {i32}:result1 = 4</i>
5527%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
5528%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
5529
5530%val2 = add i32 1, 1
5531%result2 = call i32 @llvm.atomic.swap.i32( i32* %ptr, i32 %val2 )
5532 <i>; yields {i32}:result2 = 8</i>
5533
5534%stored2 = icmp eq i32 %result2, 8 <i>; yields {i1}:stored2 = true</i>
5535%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 2</i>
5536</pre>
5537</div>
5538
5539<!-- _______________________________________________________________________ -->
5540<div class="doc_subsubsection">
5541 <a name="int_atomic_las">'<tt>llvm.atomic.las.*</tt>' Intrinsic</a>
5542
5543</div>
5544<div class="doc_text">
5545<h5>Syntax:</h5>
5546<p>
5547 This is an overloaded intrinsic. You can use <tt>llvm.atomic.las</tt> on any
5548 integer bit width. Not all targets support all bit widths however.</p>
5549<pre>
5550declare i8 @llvm.atomic.las.i8.( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
5551declare i16 @llvm.atomic.las.i16.( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
5552declare i32 @llvm.atomic.las.i32.( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
5553declare i64 @llvm.atomic.las.i64.( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
5554
5555</pre>
5556<h5>Overview:</h5>
5557<p>
5558 This intrinsic adds <tt>delta</tt> to the value stored in memory at
5559 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
5560</p>
5561<h5>Arguments:</h5>
5562<p>
5563
5564 The intrinsic takes two arguments, the first a pointer to an integer value
5565 and the second an integer value. The result is also an integer value. These
5566 integer types can have any bit width, but they must all have the same bit
5567 width. The targets may only lower integer representations they support.
5568</p>
5569<h5>Semantics:</h5>
5570<p>
5571 This intrinsic does a series of operations atomically. It first loads the
5572 value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result
5573 to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
5574</p>
5575
5576<h5>Examples:</h5>
5577<pre>
5578%ptr = malloc i32
5579 store i32 4, %ptr
5580%result1 = call i32 @llvm.atomic.las.i32( i32* %ptr, i32 4 )
5581 <i>; yields {i32}:result1 = 4</i>
5582%result2 = call i32 @llvm.atomic.las.i32( i32* %ptr, i32 2 )
5583 <i>; yields {i32}:result2 = 8</i>
5584%result3 = call i32 @llvm.atomic.las.i32( i32* %ptr, i32 5 )
5585 <i>; yields {i32}:result3 = 10</i>
5586%memval = load i32* %ptr <i>; yields {i32}:memval1 = 15</i>
5587</pre>
5588</div>
5589
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]5590
5591<!-- ======================================================================= -->
5592<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5593 <a name="int_general">General Intrinsics</a>
5594</div>
5595
5596<div class="doc_text">
5597<p> This class of intrinsics is designed to be generic and has
5598no specific purpose. </p>
5599</div>
5600
5601<!-- _______________________________________________________________________ -->
5602<div class="doc_subsubsection">
5603 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
5604</div>
5605
5606<div class="doc_text">
5607
5608<h5>Syntax:</h5>
5609<pre>
5610 declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5611</pre>
5612
5613<h5>Overview:</h5>
5614
5615<p>
5616The '<tt>llvm.var.annotation</tt>' intrinsic
5617</p>
5618
5619<h5>Arguments:</h5>
5620
5621<p>
5622The first argument is a pointer to a value, the second is a pointer to a
5623global string, the third is a pointer to a global string which is the source
5624file name, and the last argument is the line number.
5625</p>
5626
5627<h5>Semantics:</h5>
5628
5629<p>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]5630This intrinsic allows annotation of local variables with arbitrary strings.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5631This can be useful for special purpose optimizations that want to look for these
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]5632annotations. These have no other defined use, they are ignored by code
5633generation and optimization.
5634</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5635</div>
5636
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5637<!-- _______________________________________________________________________ -->
5638<div class="doc_subsubsection">
Tanya Lattnerc9869b12007-09-21 23:57:59 +0000[diff] [blame]5639 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5640</div>
5641
5642<div class="doc_text">
5643
5644<h5>Syntax:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5645<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
5646any integer bit width.
5647</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5648<pre>
Tanya Lattner09161fe2007-09-22 00:03:01 +0000[diff] [blame]5649 declare i8 @llvm.annotation.i8(i8 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5650 declare i16 @llvm.annotation.i16(i16 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5651 declare i32 @llvm.annotation.i32(i32 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5652 declare i64 @llvm.annotation.i64(i64 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5653 declare i256 @llvm.annotation.i256(i256 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5654</pre>
5655
5656<h5>Overview:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5657
5658<p>
5659The '<tt>llvm.annotation</tt>' intrinsic.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5660</p>
5661
5662<h5>Arguments:</h5>
5663
5664<p>
5665The first argument is an integer value (result of some expression),
5666the second is a pointer to a global string, the third is a pointer to a global
5667string which is the source file name, and the last argument is the line number.
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5668It returns the value of the first argument.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5669</p>
5670
5671<h5>Semantics:</h5>
5672
5673<p>
5674This intrinsic allows annotations to be put on arbitrary expressions
5675with arbitrary strings. This can be useful for special purpose optimizations
5676that want to look for these annotations. These have no other defined use, they
5677are ignored by code generation and optimization.
5678</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5679
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]5680<!-- _______________________________________________________________________ -->
5681<div class="doc_subsubsection">
5682 <a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
5683</div>
5684
5685<div class="doc_text">
5686
5687<h5>Syntax:</h5>
5688<pre>
5689 declare void @llvm.trap()
5690</pre>
5691
5692<h5>Overview:</h5>
5693
5694<p>
5695The '<tt>llvm.trap</tt>' intrinsic
5696</p>
5697
5698<h5>Arguments:</h5>
5699
5700<p>
5701None
5702</p>
5703
5704<h5>Semantics:</h5>
5705
5706<p>
5707This intrinsics is lowered to the target dependent trap instruction. If the
5708target does not have a trap instruction, this intrinsic will be lowered to the
5709call of the abort() function.
5710</p>
5711</div>
5712
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5713<!-- *********************************************************************** -->
5714<hr>
5715<address>
5716 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
5717 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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5721 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
5722 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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