Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / dd0049d223f3964a691143538e7717860189afa4 / . / docs / LangRef.html
blob: fd40c92f9aab93c4f05032f4e2db8968ebc189ff [file] [log] [blame]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
10 <link rel="stylesheet" href="llvm.css" type="text/css">
11</head>
12
13<body>
14
15<div class="doc_title"> LLVM Language Reference Manual </div>
16<ol>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
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>
36 <li><a href="#t_primitive">Primitive Types</a>
37 <ol>
38 <li><a href="#t_classifications">Type Classifications</a></li>
39 </ol>
40 </li>
41 <li><a href="#t_derived">Derived Types</a>
42 <ol>
43 <li><a href="#t_array">Array Type</a></li>
44 <li><a href="#t_function">Function Type</a></li>
45 <li><a href="#t_pointer">Pointer Type</a></li>
46 <li><a href="#t_struct">Structure Type</a></li>
47 <li><a href="#t_pstruct">Packed Structure Type</a></li>
48 <li><a href="#t_vector">Vector Type</a></li>
49 <li><a href="#t_opaque">Opaque Type</a></li>
50 </ol>
51 </li>
52 </ol>
53 </li>
54 <li><a href="#constants">Constants</a>
55 <ol>
56 <li><a href="#simpleconstants">Simple Constants</a>
57 <li><a href="#aggregateconstants">Aggregate Constants</a>
58 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
59 <li><a href="#undefvalues">Undefined Values</a>
60 <li><a href="#constantexprs">Constant Expressions</a>
61 </ol>
62 </li>
63 <li><a href="#othervalues">Other Values</a>
64 <ol>
65 <li><a href="#inlineasm">Inline Assembler Expressions</a>
66 </ol>
67 </li>
68 <li><a href="#instref">Instruction Reference</a>
69 <ol>
70 <li><a href="#terminators">Terminator Instructions</a>
71 <ol>
72 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
73 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
74 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
75 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
76 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
77 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
78 </ol>
79 </li>
80 <li><a href="#binaryops">Binary Operations</a>
81 <ol>
82 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
83 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
84 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
85 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
86 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
87 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
88 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
89 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
90 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
91 </ol>
92 </li>
93 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
94 <ol>
95 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
96 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
97 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
98 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
99 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
100 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
101 </ol>
102 </li>
103 <li><a href="#vectorops">Vector Operations</a>
104 <ol>
105 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
106 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
107 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
108 </ol>
109 </li>
110 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
111 <ol>
112 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
113 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
114 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
115 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
116 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
117 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
118 </ol>
119 </li>
120 <li><a href="#convertops">Conversion Operations</a>
121 <ol>
122 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
123 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
124 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
125 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
126 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
127 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
128 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
129 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
130 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
131 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
132 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
133 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
134 </ol>
135 <li><a href="#otherops">Other Operations</a>
136 <ol>
137 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
138 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
139 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
140 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
141 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
142 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
143 </ol>
144 </li>
145 </ol>
146 </li>
147 <li><a href="#intrinsics">Intrinsic Functions</a>
148 <ol>
149 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
150 <ol>
151 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
152 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
153 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
154 </ol>
155 </li>
156 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
157 <ol>
158 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
159 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
160 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
161 </ol>
162 </li>
163 <li><a href="#int_codegen">Code Generator Intrinsics</a>
164 <ol>
165 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
166 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
167 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
168 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
169 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
170 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
171 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
172 </ol>
173 </li>
174 <li><a href="#int_libc">Standard C Library Intrinsics</a>
175 <ol>
176 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
177 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
178 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
179 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
180 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]181 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
182 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
183 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]184 </ol>
185 </li>
186 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
187 <ol>
188 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
189 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
190 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
191 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
192 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
193 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
194 </ol>
195 </li>
196 <li><a href="#int_debugger">Debugger intrinsics</a></li>
197 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]198 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]199 <ol>
200 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]201 </ol>
202 </li>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]203 <li><a href="#int_general">General intrinsics</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]204 <ol>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]205 <li><a href="#int_var_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]206 <tt>llvm.var.annotation</tt>' Intrinsic</a></li>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]207 </ol>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]208 <ol>
209 <li><a href="#int_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]210 <tt>llvm.annotation.*</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]211 </ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]212 </li>
213 </ol>
214 </li>
215</ol>
216
217<div class="doc_author">
218 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
219 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
220</div>
221
222<!-- *********************************************************************** -->
223<div class="doc_section"> <a name="abstract">Abstract </a></div>
224<!-- *********************************************************************** -->
225
226<div class="doc_text">
227<p>This document is a reference manual for the LLVM assembly language.
228LLVM is an SSA based representation that provides type safety,
229low-level operations, flexibility, and the capability of representing
230'all' high-level languages cleanly. It is the common code
231representation used throughout all phases of the LLVM compilation
232strategy.</p>
233</div>
234
235<!-- *********************************************************************** -->
236<div class="doc_section"> <a name="introduction">Introduction</a> </div>
237<!-- *********************************************************************** -->
238
239<div class="doc_text">
240
241<p>The LLVM code representation is designed to be used in three
242different forms: as an in-memory compiler IR, as an on-disk bitcode
243representation (suitable for fast loading by a Just-In-Time compiler),
244and as a human readable assembly language representation. This allows
245LLVM to provide a powerful intermediate representation for efficient
246compiler transformations and analysis, while providing a natural means
247to debug and visualize the transformations. The three different forms
248of LLVM are all equivalent. This document describes the human readable
249representation and notation.</p>
250
251<p>The LLVM representation aims to be light-weight and low-level
252while being expressive, typed, and extensible at the same time. It
253aims to be a "universal IR" of sorts, by being at a low enough level
254that high-level ideas may be cleanly mapped to it (similar to how
255microprocessors are "universal IR's", allowing many source languages to
256be mapped to them). By providing type information, LLVM can be used as
257the target of optimizations: for example, through pointer analysis, it
258can be proven that a C automatic variable is never accessed outside of
259the current function... allowing it to be promoted to a simple SSA
260value instead of a memory location.</p>
261
262</div>
263
264<!-- _______________________________________________________________________ -->
265<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
266
267<div class="doc_text">
268
269<p>It is important to note that this document describes 'well formed'
270LLVM assembly language. There is a difference between what the parser
271accepts and what is considered 'well formed'. For example, the
272following instruction is syntactically okay, but not well formed:</p>
273
274<div class="doc_code">
275<pre>
276%x = <a href="#i_add">add</a> i32 1, %x
277</pre>
278</div>
279
280<p>...because the definition of <tt>%x</tt> does not dominate all of
281its uses. The LLVM infrastructure provides a verification pass that may
282be used to verify that an LLVM module is well formed. This pass is
283automatically run by the parser after parsing input assembly and by
284the optimizer before it outputs bitcode. The violations pointed out
285by the verifier pass indicate bugs in transformation passes or input to
286the parser.</p>
287</div>
288
Chris Lattnera83fdc02007-10-03 17:34:29 +0000[diff] [blame]289<!-- Describe the typesetting conventions here. -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]290
291<!-- *********************************************************************** -->
292<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
293<!-- *********************************************************************** -->
294
295<div class="doc_text">
296
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]297 <p>LLVM identifiers come in two basic types: global and local. Global
298 identifiers (functions, global variables) begin with the @ character. Local
299 identifiers (register names, types) begin with the % character. Additionally,
300 there are three different formats for identifiers, for different purposes:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]301
302<ol>
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]303 <li>Named values are represented as a string of characters with their prefix.
304 For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
305 regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]306 Identifiers which require other characters in their names can be surrounded
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]307 with quotes. In this way, anything except a <tt>&quot;</tt> character can
308 be used in a named value.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]309
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]310 <li>Unnamed values are represented as an unsigned numeric value with their
311 prefix. For example, %12, @2, %44.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]312
313 <li>Constants, which are described in a <a href="#constants">section about
314 constants</a>, below.</li>
315</ol>
316
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]317<p>LLVM requires that values start with a prefix for two reasons: Compilers
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]318don't need to worry about name clashes with reserved words, and the set of
319reserved words may be expanded in the future without penalty. Additionally,
320unnamed identifiers allow a compiler to quickly come up with a temporary
321variable without having to avoid symbol table conflicts.</p>
322
323<p>Reserved words in LLVM are very similar to reserved words in other
324languages. There are keywords for different opcodes
325('<tt><a href="#i_add">add</a></tt>',
326 '<tt><a href="#i_bitcast">bitcast</a></tt>',
327 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
328href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
329and others. These reserved words cannot conflict with variable names, because
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]330none of them start with a prefix character ('%' or '@').</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]331
332<p>Here is an example of LLVM code to multiply the integer variable
333'<tt>%X</tt>' by 8:</p>
334
335<p>The easy way:</p>
336
337<div class="doc_code">
338<pre>
339%result = <a href="#i_mul">mul</a> i32 %X, 8
340</pre>
341</div>
342
343<p>After strength reduction:</p>
344
345<div class="doc_code">
346<pre>
347%result = <a href="#i_shl">shl</a> i32 %X, i8 3
348</pre>
349</div>
350
351<p>And the hard way:</p>
352
353<div class="doc_code">
354<pre>
355<a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
356<a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
357%result = <a href="#i_add">add</a> i32 %1, %1
358</pre>
359</div>
360
361<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
362important lexical features of LLVM:</p>
363
364<ol>
365
366 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
367 line.</li>
368
369 <li>Unnamed temporaries are created when the result of a computation is not
370 assigned to a named value.</li>
371
372 <li>Unnamed temporaries are numbered sequentially</li>
373
374</ol>
375
376<p>...and it also shows a convention that we follow in this document. When
377demonstrating instructions, we will follow an instruction with a comment that
378defines the type and name of value produced. Comments are shown in italic
379text.</p>
380
381</div>
382
383<!-- *********************************************************************** -->
384<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
385<!-- *********************************************************************** -->
386
387<!-- ======================================================================= -->
388<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
389</div>
390
391<div class="doc_text">
392
393<p>LLVM programs are composed of "Module"s, each of which is a
394translation unit of the input programs. Each module consists of
395functions, global variables, and symbol table entries. Modules may be
396combined together with the LLVM linker, which merges function (and
397global variable) definitions, resolves forward declarations, and merges
398symbol table entries. Here is an example of the "hello world" module:</p>
399
400<div class="doc_code">
401<pre><i>; Declare the string constant as a global constant...</i>
402<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
403 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
404
405<i>; External declaration of the puts function</i>
406<a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
407
408<i>; Definition of main function</i>
409define i32 @main() { <i>; i32()* </i>
410 <i>; Convert [13x i8 ]* to i8 *...</i>
411 %cast210 = <a
412 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
413
414 <i>; Call puts function to write out the string to stdout...</i>
415 <a
416 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
417 <a
418 href="#i_ret">ret</a> i32 0<br>}<br>
419</pre>
420</div>
421
422<p>This example is made up of a <a href="#globalvars">global variable</a>
423named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
424function, and a <a href="#functionstructure">function definition</a>
425for "<tt>main</tt>".</p>
426
427<p>In general, a module is made up of a list of global values,
428where both functions and global variables are global values. Global values are
429represented by a pointer to a memory location (in this case, a pointer to an
430array of char, and a pointer to a function), and have one of the following <a
431href="#linkage">linkage types</a>.</p>
432
433</div>
434
435<!-- ======================================================================= -->
436<div class="doc_subsection">
437 <a name="linkage">Linkage Types</a>
438</div>
439
440<div class="doc_text">
441
442<p>
443All Global Variables and Functions have one of the following types of linkage:
444</p>
445
446<dl>
447
448 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
449
450 <dd>Global values with internal linkage are only directly accessible by
451 objects in the current module. In particular, linking code into a module with
452 an internal global value may cause the internal to be renamed as necessary to
453 avoid collisions. Because the symbol is internal to the module, all
454 references can be updated. This corresponds to the notion of the
455 '<tt>static</tt>' keyword in C.
456 </dd>
457
458 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
459
460 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
461 the same name when linkage occurs. This is typically used to implement
462 inline functions, templates, or other code which must be generated in each
463 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
464 allowed to be discarded.
465 </dd>
466
467 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
468
469 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
470 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
471 used for globals that may be emitted in multiple translation units, but that
472 are not guaranteed to be emitted into every translation unit that uses them.
473 One example of this are common globals in C, such as "<tt>int X;</tt>" at
474 global scope.
475 </dd>
476
477 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
478
479 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
480 pointer to array type. When two global variables with appending linkage are
481 linked together, the two global arrays are appended together. This is the
482 LLVM, typesafe, equivalent of having the system linker append together
483 "sections" with identical names when .o files are linked.
484 </dd>
485
486 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
487 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
488 until linked, if not linked, the symbol becomes null instead of being an
489 undefined reference.
490 </dd>
491
492 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
493
494 <dd>If none of the above identifiers are used, the global is externally
495 visible, meaning that it participates in linkage and can be used to resolve
496 external symbol references.
497 </dd>
498</dl>
499
500 <p>
501 The next two types of linkage are targeted for Microsoft Windows platform
502 only. They are designed to support importing (exporting) symbols from (to)
503 DLLs.
504 </p>
505
506 <dl>
507 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
508
509 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
510 or variable via a global pointer to a pointer that is set up by the DLL
511 exporting the symbol. On Microsoft Windows targets, the pointer name is
512 formed by combining <code>_imp__</code> and the function or variable name.
513 </dd>
514
515 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
516
517 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
518 pointer to a pointer in a DLL, so that it can be referenced with the
519 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
520 name is formed by combining <code>_imp__</code> and the function or variable
521 name.
522 </dd>
523
524</dl>
525
526<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
527variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
528variable and was linked with this one, one of the two would be renamed,
529preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
530external (i.e., lacking any linkage declarations), they are accessible
531outside of the current module.</p>
532<p>It is illegal for a function <i>declaration</i>
533to have any linkage type other than "externally visible", <tt>dllimport</tt>,
534or <tt>extern_weak</tt>.</p>
535<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
536linkages.
537</div>
538
539<!-- ======================================================================= -->
540<div class="doc_subsection">
541 <a name="callingconv">Calling Conventions</a>
542</div>
543
544<div class="doc_text">
545
546<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
547and <a href="#i_invoke">invokes</a> can all have an optional calling convention
548specified for the call. The calling convention of any pair of dynamic
549caller/callee must match, or the behavior of the program is undefined. The
550following calling conventions are supported by LLVM, and more may be added in
551the future:</p>
552
553<dl>
554 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
555
556 <dd>This calling convention (the default if no other calling convention is
557 specified) matches the target C calling conventions. This calling convention
558 supports varargs function calls and tolerates some mismatch in the declared
559 prototype and implemented declaration of the function (as does normal C).
560 </dd>
561
562 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
563
564 <dd>This calling convention attempts to make calls as fast as possible
565 (e.g. by passing things in registers). This calling convention allows the
566 target to use whatever tricks it wants to produce fast code for the target,
567 without having to conform to an externally specified ABI. Implementations of
568 this convention should allow arbitrary tail call optimization to be supported.
569 This calling convention does not support varargs and requires the prototype of
570 all callees to exactly match the prototype of the function definition.
571 </dd>
572
573 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
574
575 <dd>This calling convention attempts to make code in the caller as efficient
576 as possible under the assumption that the call is not commonly executed. As
577 such, these calls often preserve all registers so that the call does not break
578 any live ranges in the caller side. This calling convention does not support
579 varargs and requires the prototype of all callees to exactly match the
580 prototype of the function definition.
581 </dd>
582
583 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
584
585 <dd>Any calling convention may be specified by number, allowing
586 target-specific calling conventions to be used. Target specific calling
587 conventions start at 64.
588 </dd>
589</dl>
590
591<p>More calling conventions can be added/defined on an as-needed basis, to
592support pascal conventions or any other well-known target-independent
593convention.</p>
594
595</div>
596
597<!-- ======================================================================= -->
598<div class="doc_subsection">
599 <a name="visibility">Visibility Styles</a>
600</div>
601
602<div class="doc_text">
603
604<p>
605All Global Variables and Functions have one of the following visibility styles:
606</p>
607
608<dl>
609 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
610
611 <dd>On ELF, default visibility means that the declaration is visible to other
612 modules and, in shared libraries, means that the declared entity may be
613 overridden. On Darwin, default visibility means that the declaration is
614 visible to other modules. Default visibility corresponds to "external
615 linkage" in the language.
616 </dd>
617
618 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
619
620 <dd>Two declarations of an object with hidden visibility refer to the same
621 object if they are in the same shared object. Usually, hidden visibility
622 indicates that the symbol will not be placed into the dynamic symbol table,
623 so no other module (executable or shared library) can reference it
624 directly.
625 </dd>
626
627 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
628
629 <dd>On ELF, protected visibility indicates that the symbol will be placed in
630 the dynamic symbol table, but that references within the defining module will
631 bind to the local symbol. That is, the symbol cannot be overridden by another
632 module.
633 </dd>
634</dl>
635
636</div>
637
638<!-- ======================================================================= -->
639<div class="doc_subsection">
640 <a name="globalvars">Global Variables</a>
641</div>
642
643<div class="doc_text">
644
645<p>Global variables define regions of memory allocated at compilation time
646instead of run-time. Global variables may optionally be initialized, may have
647an explicit section to be placed in, and may have an optional explicit alignment
648specified. A variable may be defined as "thread_local", which means that it
649will not be shared by threads (each thread will have a separated copy of the
650variable). A variable may be defined as a global "constant," which indicates
651that the contents of the variable will <b>never</b> be modified (enabling better
652optimization, allowing the global data to be placed in the read-only section of
653an executable, etc). Note that variables that need runtime initialization
654cannot be marked "constant" as there is a store to the variable.</p>
655
656<p>
657LLVM explicitly allows <em>declarations</em> of global variables to be marked
658constant, even if the final definition of the global is not. This capability
659can be used to enable slightly better optimization of the program, but requires
660the language definition to guarantee that optimizations based on the
661'constantness' are valid for the translation units that do not include the
662definition.
663</p>
664
665<p>As SSA values, global variables define pointer values that are in
666scope (i.e. they dominate) all basic blocks in the program. Global
667variables always define a pointer to their "content" type because they
668describe a region of memory, and all memory objects in LLVM are
669accessed through pointers.</p>
670
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame^]671<p>A global variable may be declared to reside in a target-specifc numbered
672address space. For targets that support them, address spaces may affect how
673optimizations are performed and/or what target instructions are used to access
674the variable. The default address space is zero.</p>
675
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]676<p>LLVM allows an explicit section to be specified for globals. If the target
677supports it, it will emit globals to the section specified.</p>
678
679<p>An explicit alignment may be specified for a global. If not present, or if
680the alignment is set to zero, the alignment of the global is set by the target
681to whatever it feels convenient. If an explicit alignment is specified, the
682global is forced to have at least that much alignment. All alignments must be
683a power of 2.</p>
684
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame^]685<p>For example, the following defines a global in a numbered address space with
686an initializer, section, and alignment:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]687
688<div class="doc_code">
689<pre>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame^]690@G = constant float 1.0 addrspace(5), section "foo", align 4
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]691</pre>
692</div>
693
694</div>
695
696
697<!-- ======================================================================= -->
698<div class="doc_subsection">
699 <a name="functionstructure">Functions</a>
700</div>
701
702<div class="doc_text">
703
704<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
705an optional <a href="#linkage">linkage type</a>, an optional
706<a href="#visibility">visibility style</a>, an optional
707<a href="#callingconv">calling convention</a>, a return type, an optional
708<a href="#paramattrs">parameter attribute</a> for the return type, a function
709name, a (possibly empty) argument list (each with optional
710<a href="#paramattrs">parameter attributes</a>), an optional section, an
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]711optional alignment, an optional <a href="#gc">garbage collector name</a>, an
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]712opening curly brace, a list of basic blocks, and a closing curly brace.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]713
714LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
715optional <a href="#linkage">linkage type</a>, an optional
716<a href="#visibility">visibility style</a>, an optional
717<a href="#callingconv">calling convention</a>, a return type, an optional
718<a href="#paramattrs">parameter attribute</a> for the return type, a function
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]719name, a possibly empty list of arguments, an optional alignment, and an optional
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]720<a href="#gc">garbage collector name</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]721
722<p>A function definition contains a list of basic blocks, forming the CFG for
723the function. Each basic block may optionally start with a label (giving the
724basic block a symbol table entry), contains a list of instructions, and ends
725with a <a href="#terminators">terminator</a> instruction (such as a branch or
726function return).</p>
727
728<p>The first basic block in a function is special in two ways: it is immediately
729executed on entrance to the function, and it is not allowed to have predecessor
730basic blocks (i.e. there can not be any branches to the entry block of a
731function). Because the block can have no predecessors, it also cannot have any
732<a href="#i_phi">PHI nodes</a>.</p>
733
734<p>LLVM allows an explicit section to be specified for functions. If the target
735supports it, it will emit functions to the section specified.</p>
736
737<p>An explicit alignment may be specified for a function. If not present, or if
738the alignment is set to zero, the alignment of the function is set by the target
739to whatever it feels convenient. If an explicit alignment is specified, the
740function is forced to have at least that much alignment. All alignments must be
741a power of 2.</p>
742
743</div>
744
745
746<!-- ======================================================================= -->
747<div class="doc_subsection">
748 <a name="aliasstructure">Aliases</a>
749</div>
750<div class="doc_text">
751 <p>Aliases act as "second name" for the aliasee value (which can be either
752 function or global variable or bitcast of global value). Aliases may have an
753 optional <a href="#linkage">linkage type</a>, and an
754 optional <a href="#visibility">visibility style</a>.</p>
755
756 <h5>Syntax:</h5>
757
758<div class="doc_code">
759<pre>
760@&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
761</pre>
762</div>
763
764</div>
765
766
767
768<!-- ======================================================================= -->
769<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
770<div class="doc_text">
771 <p>The return type and each parameter of a function type may have a set of
772 <i>parameter attributes</i> associated with them. Parameter attributes are
773 used to communicate additional information about the result or parameters of
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]774 a function. Parameter attributes are considered to be part of the function,
775 not of the function type, so functions with different parameter attributes
776 can have the same function type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]777
778 <p>Parameter attributes are simple keywords that follow the type specified. If
779 multiple parameter attributes are needed, they are space separated. For
780 example:</p>
781
782<div class="doc_code">
783<pre>
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]784declare i32 @printf(i8* noalias , ...) nounwind
785declare i32 @atoi(i8*) nounwind readonly
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]786</pre>
787</div>
788
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]789 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
790 <tt>readonly</tt>) come immediately after the argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]791
792 <p>Currently, only the following parameter attributes are defined:</p>
793 <dl>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]794 <dt><tt>zeroext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]795 <dd>This indicates that the parameter should be zero extended just before
796 a call to this function.</dd>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]797 <dt><tt>signext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]798 <dd>This indicates that the parameter should be sign extended just before
799 a call to this function.</dd>
800 <dt><tt>inreg</tt></dt>
801 <dd>This indicates that the parameter should be placed in register (if
802 possible) during assembling function call. Support for this attribute is
803 target-specific</dd>
804 <dt><tt>sret</tt></dt>
805 <dd>This indicates that the parameter specifies the address of a structure
806 that is the return value of the function in the source program.</dd>
807 <dt><tt>noalias</tt></dt>
808 <dd>This indicates that the parameter not alias any other object or any
809 other "noalias" objects during the function call.
810 <dt><tt>noreturn</tt></dt>
811 <dd>This function attribute indicates that the function never returns. This
812 indicates to LLVM that every call to this function should be treated as if
813 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
814 <dt><tt>nounwind</tt></dt>
815 <dd>This function attribute indicates that the function type does not use
816 the unwind instruction and does not allow stack unwinding to propagate
817 through it.</dd>
Duncan Sands4ee46812007-07-27 19:57:41 +0000[diff] [blame]818 <dt><tt>nest</tt></dt>
819 <dd>This indicates that the parameter can be excised using the
820 <a href="#int_trampoline">trampoline intrinsics</a>.</dd>
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]821 <dt><tt>readonly</tt></dt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]822 <dd>This function attribute indicates that the function has no side-effects
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]823 except for producing a return value or throwing an exception. The value
824 returned must only depend on the function arguments and/or global variables.
825 It may use values obtained by dereferencing pointers.</dd>
826 <dt><tt>readnone</tt></dt>
827 <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]828 function, but in addition it is not allowed to dereference any pointer arguments
829 or global variables.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]830 </dl>
831
832</div>
833
834<!-- ======================================================================= -->
835<div class="doc_subsection">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]836 <a name="gc">Garbage Collector Names</a>
837</div>
838
839<div class="doc_text">
840<p>Each function may specify a garbage collector name, which is simply a
841string.</p>
842
843<div class="doc_code"><pre
844>define void @f() gc "name" { ...</pre></div>
845
846<p>The compiler declares the supported values of <i>name</i>. Specifying a
847collector which will cause the compiler to alter its output in order to support
848the named garbage collection algorithm.</p>
849</div>
850
851<!-- ======================================================================= -->
852<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]853 <a name="moduleasm">Module-Level Inline Assembly</a>
854</div>
855
856<div class="doc_text">
857<p>
858Modules may contain "module-level inline asm" blocks, which corresponds to the
859GCC "file scope inline asm" blocks. These blocks are internally concatenated by
860LLVM and treated as a single unit, but may be separated in the .ll file if
861desired. The syntax is very simple:
862</p>
863
864<div class="doc_code">
865<pre>
866module asm "inline asm code goes here"
867module asm "more can go here"
868</pre>
869</div>
870
871<p>The strings can contain any character by escaping non-printable characters.
872 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
873 for the number.
874</p>
875
876<p>
877 The inline asm code is simply printed to the machine code .s file when
878 assembly code is generated.
879</p>
880</div>
881
882<!-- ======================================================================= -->
883<div class="doc_subsection">
884 <a name="datalayout">Data Layout</a>
885</div>
886
887<div class="doc_text">
888<p>A module may specify a target specific data layout string that specifies how
889data is to be laid out in memory. The syntax for the data layout is simply:</p>
890<pre> target datalayout = "<i>layout specification</i>"</pre>
891<p>The <i>layout specification</i> consists of a list of specifications
892separated by the minus sign character ('-'). Each specification starts with a
893letter and may include other information after the letter to define some
894aspect of the data layout. The specifications accepted are as follows: </p>
895<dl>
896 <dt><tt>E</tt></dt>
897 <dd>Specifies that the target lays out data in big-endian form. That is, the
898 bits with the most significance have the lowest address location.</dd>
899 <dt><tt>e</tt></dt>
900 <dd>Specifies that hte target lays out data in little-endian form. That is,
901 the bits with the least significance have the lowest address location.</dd>
902 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
903 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
904 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
905 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
906 too.</dd>
907 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
908 <dd>This specifies the alignment for an integer type of a given bit
909 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
910 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
911 <dd>This specifies the alignment for a vector type of a given bit
912 <i>size</i>.</dd>
913 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
914 <dd>This specifies the alignment for a floating point type of a given bit
915 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
916 (double).</dd>
917 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
918 <dd>This specifies the alignment for an aggregate type of a given bit
919 <i>size</i>.</dd>
920</dl>
921<p>When constructing the data layout for a given target, LLVM starts with a
922default set of specifications which are then (possibly) overriden by the
923specifications in the <tt>datalayout</tt> keyword. The default specifications
924are given in this list:</p>
925<ul>
926 <li><tt>E</tt> - big endian</li>
927 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
928 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
929 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
930 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
931 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
932 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
933 alignment of 64-bits</li>
934 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
935 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
936 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
937 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
938 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
939</ul>
940<p>When llvm is determining the alignment for a given type, it uses the
941following rules:
942<ol>
943 <li>If the type sought is an exact match for one of the specifications, that
944 specification is used.</li>
945 <li>If no match is found, and the type sought is an integer type, then the
946 smallest integer type that is larger than the bitwidth of the sought type is
947 used. If none of the specifications are larger than the bitwidth then the the
948 largest integer type is used. For example, given the default specifications
949 above, the i7 type will use the alignment of i8 (next largest) while both
950 i65 and i256 will use the alignment of i64 (largest specified).</li>
951 <li>If no match is found, and the type sought is a vector type, then the
952 largest vector type that is smaller than the sought vector type will be used
953 as a fall back. This happens because <128 x double> can be implemented in
954 terms of 64 <2 x double>, for example.</li>
955</ol>
956</div>
957
958<!-- *********************************************************************** -->
959<div class="doc_section"> <a name="typesystem">Type System</a> </div>
960<!-- *********************************************************************** -->
961
962<div class="doc_text">
963
964<p>The LLVM type system is one of the most important features of the
965intermediate representation. Being typed enables a number of
966optimizations to be performed on the IR directly, without having to do
967extra analyses on the side before the transformation. A strong type
968system makes it easier to read the generated code and enables novel
969analyses and transformations that are not feasible to perform on normal
970three address code representations.</p>
971
972</div>
973
974<!-- ======================================================================= -->
975<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
976<div class="doc_text">
977<p>The primitive types are the fundamental building blocks of the LLVM
978system. The current set of primitive types is as follows:</p>
979
980<table class="layout">
981 <tr class="layout">
982 <td class="left">
983 <table>
984 <tbody>
985 <tr><th>Type</th><th>Description</th></tr>
986 <tr><td><tt><a name="t_void">void</a></tt></td><td>No value</td></tr>
987 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
988 </tbody>
989 </table>
990 </td>
991 <td class="right">
992 <table>
993 <tbody>
994 <tr><th>Type</th><th>Description</th></tr>
995 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
996 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
997 </tbody>
998 </table>
999 </td>
1000 </tr>
1001</table>
1002</div>
1003
1004<!-- _______________________________________________________________________ -->
1005<div class="doc_subsubsection"> <a name="t_classifications">Type
1006Classifications</a> </div>
1007<div class="doc_text">
1008<p>These different primitive types fall into a few useful
1009classifications:</p>
1010
1011<table border="1" cellspacing="0" cellpadding="4">
1012 <tbody>
1013 <tr><th>Classification</th><th>Types</th></tr>
1014 <tr>
1015 <td><a name="t_integer">integer</a></td>
1016 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1017 </tr>
1018 <tr>
1019 <td><a name="t_floating">floating point</a></td>
1020 <td><tt>float, double</tt></td>
1021 </tr>
1022 <tr>
1023 <td><a name="t_firstclass">first class</a></td>
1024 <td><tt>i1, ..., float, double, <br/>
1025 <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
1026 </td>
1027 </tr>
1028 </tbody>
1029</table>
1030
1031<p>The <a href="#t_firstclass">first class</a> types are perhaps the
1032most important. Values of these types are the only ones which can be
1033produced by instructions, passed as arguments, or used as operands to
1034instructions. This means that all structures and arrays must be
1035manipulated either by pointer or by component.</p>
1036</div>
1037
1038<!-- ======================================================================= -->
1039<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1040
1041<div class="doc_text">
1042
1043<p>The real power in LLVM comes from the derived types in the system.
1044This is what allows a programmer to represent arrays, functions,
1045pointers, and other useful types. Note that these derived types may be
1046recursive: For example, it is possible to have a two dimensional array.</p>
1047
1048</div>
1049
1050<!-- _______________________________________________________________________ -->
1051<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1052
1053<div class="doc_text">
1054
1055<h5>Overview:</h5>
1056<p>The integer type is a very simple derived type that simply specifies an
1057arbitrary bit width for the integer type desired. Any bit width from 1 bit to
10582^23-1 (about 8 million) can be specified.</p>
1059
1060<h5>Syntax:</h5>
1061
1062<pre>
1063 iN
1064</pre>
1065
1066<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1067value.</p>
1068
1069<h5>Examples:</h5>
1070<table class="layout">
1071 <tr class="layout">
1072 <td class="left">
1073 <tt>i1</tt><br/>
1074 <tt>i4</tt><br/>
1075 <tt>i8</tt><br/>
1076 <tt>i16</tt><br/>
1077 <tt>i32</tt><br/>
1078 <tt>i42</tt><br/>
1079 <tt>i64</tt><br/>
1080 <tt>i1942652</tt><br/>
1081 </td>
1082 <td class="left">
1083 A boolean integer of 1 bit<br/>
1084 A nibble sized integer of 4 bits.<br/>
1085 A byte sized integer of 8 bits.<br/>
1086 A half word sized integer of 16 bits.<br/>
1087 A word sized integer of 32 bits.<br/>
1088 An integer whose bit width is the answer. <br/>
1089 A double word sized integer of 64 bits.<br/>
1090 A really big integer of over 1 million bits.<br/>
1091 </td>
1092 </tr>
1093</table>
1094</div>
1095
1096<!-- _______________________________________________________________________ -->
1097<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1098
1099<div class="doc_text">
1100
1101<h5>Overview:</h5>
1102
1103<p>The array type is a very simple derived type that arranges elements
1104sequentially in memory. The array type requires a size (number of
1105elements) and an underlying data type.</p>
1106
1107<h5>Syntax:</h5>
1108
1109<pre>
1110 [&lt;# elements&gt; x &lt;elementtype&gt;]
1111</pre>
1112
1113<p>The number of elements is a constant integer value; elementtype may
1114be any type with a size.</p>
1115
1116<h5>Examples:</h5>
1117<table class="layout">
1118 <tr class="layout">
1119 <td class="left">
1120 <tt>[40 x i32 ]</tt><br/>
1121 <tt>[41 x i32 ]</tt><br/>
1122 <tt>[40 x i8]</tt><br/>
1123 </td>
1124 <td class="left">
1125 Array of 40 32-bit integer values.<br/>
1126 Array of 41 32-bit integer values.<br/>
1127 Array of 40 8-bit integer values.<br/>
1128 </td>
1129 </tr>
1130</table>
1131<p>Here are some examples of multidimensional arrays:</p>
1132<table class="layout">
1133 <tr class="layout">
1134 <td class="left">
1135 <tt>[3 x [4 x i32]]</tt><br/>
1136 <tt>[12 x [10 x float]]</tt><br/>
1137 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
1138 </td>
1139 <td class="left">
1140 3x4 array of 32-bit integer values.<br/>
1141 12x10 array of single precision floating point values.<br/>
1142 2x3x4 array of 16-bit integer values.<br/>
1143 </td>
1144 </tr>
1145</table>
1146
1147<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1148length array. Normally, accesses past the end of an array are undefined in
1149LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1150As a special case, however, zero length arrays are recognized to be variable
1151length. This allows implementation of 'pascal style arrays' with the LLVM
1152type "{ i32, [0 x float]}", for example.</p>
1153
1154</div>
1155
1156<!-- _______________________________________________________________________ -->
1157<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1158<div class="doc_text">
1159<h5>Overview:</h5>
1160<p>The function type can be thought of as a function signature. It
1161consists of a return type and a list of formal parameter types.
1162Function types are usually used to build virtual function tables
1163(which are structures of pointers to functions), for indirect function
1164calls, and when defining a function.</p>
1165<p>
1166The return type of a function type cannot be an aggregate type.
1167</p>
1168<h5>Syntax:</h5>
1169<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
1170<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
1171specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1172which indicates that the function takes a variable number of arguments.
1173Variable argument functions can access their arguments with the <a
1174 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
1175<h5>Examples:</h5>
1176<table class="layout">
1177 <tr class="layout">
1178 <td class="left"><tt>i32 (i32)</tt></td>
1179 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1180 </td>
1181 </tr><tr class="layout">
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]1182 <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1183 </tt></td>
1184 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1185 an <tt>i16</tt> that should be sign extended and a
1186 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1187 <tt>float</tt>.
1188 </td>
1189 </tr><tr class="layout">
1190 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1191 <td class="left">A vararg function that takes at least one
1192 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1193 which returns an integer. This is the signature for <tt>printf</tt> in
1194 LLVM.
1195 </td>
1196 </tr>
1197</table>
1198
1199</div>
1200<!-- _______________________________________________________________________ -->
1201<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1202<div class="doc_text">
1203<h5>Overview:</h5>
1204<p>The structure type is used to represent a collection of data members
1205together in memory. The packing of the field types is defined to match
1206the ABI of the underlying processor. The elements of a structure may
1207be any type that has a size.</p>
1208<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1209and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1210field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1211instruction.</p>
1212<h5>Syntax:</h5>
1213<pre> { &lt;type list&gt; }<br></pre>
1214<h5>Examples:</h5>
1215<table class="layout">
1216 <tr class="layout">
1217 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1218 <td class="left">A triple of three <tt>i32</tt> values</td>
1219 </tr><tr class="layout">
1220 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1221 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1222 second element is a <a href="#t_pointer">pointer</a> to a
1223 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1224 an <tt>i32</tt>.</td>
1225 </tr>
1226</table>
1227</div>
1228
1229<!-- _______________________________________________________________________ -->
1230<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1231</div>
1232<div class="doc_text">
1233<h5>Overview:</h5>
1234<p>The packed structure type is used to represent a collection of data members
1235together in memory. There is no padding between fields. Further, the alignment
1236of a packed structure is 1 byte. The elements of a packed structure may
1237be any type that has a size.</p>
1238<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1239and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1240field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1241instruction.</p>
1242<h5>Syntax:</h5>
1243<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1244<h5>Examples:</h5>
1245<table class="layout">
1246 <tr class="layout">
1247 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1248 <td class="left">A triple of three <tt>i32</tt> values</td>
1249 </tr><tr class="layout">
1250 <td class="left"><tt>&lt;&nbsp;{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}&nbsp;&gt;</tt></td>
1251 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1252 second element is a <a href="#t_pointer">pointer</a> to a
1253 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1254 an <tt>i32</tt>.</td>
1255 </tr>
1256</table>
1257</div>
1258
1259<!-- _______________________________________________________________________ -->
1260<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1261<div class="doc_text">
1262<h5>Overview:</h5>
1263<p>As in many languages, the pointer type represents a pointer or
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame^]1264reference to another object, which must live in memory. Pointer types may have
1265an optional address space attribute defining the target-specific numbered
1266address space where the pointed-to object resides. The default address space is
1267zero.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1268<h5>Syntax:</h5>
1269<pre> &lt;type&gt; *<br></pre>
1270<h5>Examples:</h5>
1271<table class="layout">
1272 <tr class="layout">
1273 <td class="left">
1274 <tt>[4x i32]*</tt><br/>
1275 <tt>i32 (i32 *) *</tt><br/>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame^]1276 <tt>i32 addrspace(5)*</tt><br/>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1277 </td>
1278 <td class="left">
1279 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
1280 four <tt>i32</tt> values<br/>
1281 A <a href="#t_pointer">pointer</a> to a <a
1282 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1283 <tt>i32</tt>.<br/>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame^]1284 A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value that resides
1285 in address space 5.<br/>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1286 </td>
1287 </tr>
1288</table>
1289</div>
1290
1291<!-- _______________________________________________________________________ -->
1292<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1293<div class="doc_text">
1294
1295<h5>Overview:</h5>
1296
1297<p>A vector type is a simple derived type that represents a vector
1298of elements. Vector types are used when multiple primitive data
1299are operated in parallel using a single instruction (SIMD).
1300A vector type requires a size (number of
1301elements) and an underlying primitive data type. Vectors must have a power
1302of two length (1, 2, 4, 8, 16 ...). Vector types are
1303considered <a href="#t_firstclass">first class</a>.</p>
1304
1305<h5>Syntax:</h5>
1306
1307<pre>
1308 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1309</pre>
1310
1311<p>The number of elements is a constant integer value; elementtype may
1312be any integer or floating point type.</p>
1313
1314<h5>Examples:</h5>
1315
1316<table class="layout">
1317 <tr class="layout">
1318 <td class="left">
1319 <tt>&lt;4 x i32&gt;</tt><br/>
1320 <tt>&lt;8 x float&gt;</tt><br/>
1321 <tt>&lt;2 x i64&gt;</tt><br/>
1322 </td>
1323 <td class="left">
1324 Vector of 4 32-bit integer values.<br/>
1325 Vector of 8 floating-point values.<br/>
1326 Vector of 2 64-bit integer values.<br/>
1327 </td>
1328 </tr>
1329</table>
1330</div>
1331
1332<!-- _______________________________________________________________________ -->
1333<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1334<div class="doc_text">
1335
1336<h5>Overview:</h5>
1337
1338<p>Opaque types are used to represent unknown types in the system. This
Gordon Henriksenda0706e2007-10-14 00:34:53 +0000[diff] [blame]1339corresponds (for example) to the C notion of a forward declared structure type.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1340In LLVM, opaque types can eventually be resolved to any type (not just a
1341structure type).</p>
1342
1343<h5>Syntax:</h5>
1344
1345<pre>
1346 opaque
1347</pre>
1348
1349<h5>Examples:</h5>
1350
1351<table class="layout">
1352 <tr class="layout">
1353 <td class="left">
1354 <tt>opaque</tt>
1355 </td>
1356 <td class="left">
1357 An opaque type.<br/>
1358 </td>
1359 </tr>
1360</table>
1361</div>
1362
1363
1364<!-- *********************************************************************** -->
1365<div class="doc_section"> <a name="constants">Constants</a> </div>
1366<!-- *********************************************************************** -->
1367
1368<div class="doc_text">
1369
1370<p>LLVM has several different basic types of constants. This section describes
1371them all and their syntax.</p>
1372
1373</div>
1374
1375<!-- ======================================================================= -->
1376<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1377
1378<div class="doc_text">
1379
1380<dl>
1381 <dt><b>Boolean constants</b></dt>
1382
1383 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1384 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1385 </dd>
1386
1387 <dt><b>Integer constants</b></dt>
1388
1389 <dd>Standard integers (such as '4') are constants of the <a
1390 href="#t_integer">integer</a> type. Negative numbers may be used with
1391 integer types.
1392 </dd>
1393
1394 <dt><b>Floating point constants</b></dt>
1395
1396 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1397 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
1398 notation (see below). Floating point constants must have a <a
1399 href="#t_floating">floating point</a> type. </dd>
1400
1401 <dt><b>Null pointer constants</b></dt>
1402
1403 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1404 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1405
1406</dl>
1407
1408<p>The one non-intuitive notation for constants is the optional hexadecimal form
1409of floating point constants. For example, the form '<tt>double
14100x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
14114.5e+15</tt>'. The only time hexadecimal floating point constants are required
1412(and the only time that they are generated by the disassembler) is when a
1413floating point constant must be emitted but it cannot be represented as a
1414decimal floating point number. For example, NaN's, infinities, and other
1415special values are represented in their IEEE hexadecimal format so that
1416assembly and disassembly do not cause any bits to change in the constants.</p>
1417
1418</div>
1419
1420<!-- ======================================================================= -->
1421<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1422</div>
1423
1424<div class="doc_text">
1425<p>Aggregate constants arise from aggregation of simple constants
1426and smaller aggregate constants.</p>
1427
1428<dl>
1429 <dt><b>Structure constants</b></dt>
1430
1431 <dd>Structure constants are represented with notation similar to structure
1432 type definitions (a comma separated list of elements, surrounded by braces
1433 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1434 where "<tt>%G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
1435 must have <a href="#t_struct">structure type</a>, and the number and
1436 types of elements must match those specified by the type.
1437 </dd>
1438
1439 <dt><b>Array constants</b></dt>
1440
1441 <dd>Array constants are represented with notation similar to array type
1442 definitions (a comma separated list of elements, surrounded by square brackets
1443 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1444 constants must have <a href="#t_array">array type</a>, and the number and
1445 types of elements must match those specified by the type.
1446 </dd>
1447
1448 <dt><b>Vector constants</b></dt>
1449
1450 <dd>Vector constants are represented with notation similar to vector type
1451 definitions (a comma separated list of elements, surrounded by
1452 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1453 i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must have <a
1454 href="#t_vector">vector type</a>, and the number and types of elements must
1455 match those specified by the type.
1456 </dd>
1457
1458 <dt><b>Zero initialization</b></dt>
1459
1460 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1461 value to zero of <em>any</em> type, including scalar and aggregate types.
1462 This is often used to avoid having to print large zero initializers (e.g. for
1463 large arrays) and is always exactly equivalent to using explicit zero
1464 initializers.
1465 </dd>
1466</dl>
1467
1468</div>
1469
1470<!-- ======================================================================= -->
1471<div class="doc_subsection">
1472 <a name="globalconstants">Global Variable and Function Addresses</a>
1473</div>
1474
1475<div class="doc_text">
1476
1477<p>The addresses of <a href="#globalvars">global variables</a> and <a
1478href="#functionstructure">functions</a> are always implicitly valid (link-time)
1479constants. These constants are explicitly referenced when the <a
1480href="#identifiers">identifier for the global</a> is used and always have <a
1481href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1482file:</p>
1483
1484<div class="doc_code">
1485<pre>
1486@X = global i32 17
1487@Y = global i32 42
1488@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1489</pre>
1490</div>
1491
1492</div>
1493
1494<!-- ======================================================================= -->
1495<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1496<div class="doc_text">
1497 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1498 no specific value. Undefined values may be of any type and be used anywhere
1499 a constant is permitted.</p>
1500
1501 <p>Undefined values indicate to the compiler that the program is well defined
1502 no matter what value is used, giving the compiler more freedom to optimize.
1503 </p>
1504</div>
1505
1506<!-- ======================================================================= -->
1507<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1508</div>
1509
1510<div class="doc_text">
1511
1512<p>Constant expressions are used to allow expressions involving other constants
1513to be used as constants. Constant expressions may be of any <a
1514href="#t_firstclass">first class</a> type and may involve any LLVM operation
1515that does not have side effects (e.g. load and call are not supported). The
1516following is the syntax for constant expressions:</p>
1517
1518<dl>
1519 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1520 <dd>Truncate a constant to another type. The bit size of CST must be larger
1521 than the bit size of TYPE. Both types must be integers.</dd>
1522
1523 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1524 <dd>Zero extend a constant to another type. The bit size of CST must be
1525 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1526
1527 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1528 <dd>Sign extend a constant to another type. The bit size of CST must be
1529 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1530
1531 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1532 <dd>Truncate a floating point constant to another floating point type. The
1533 size of CST must be larger than the size of TYPE. Both types must be
1534 floating point.</dd>
1535
1536 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1537 <dd>Floating point extend a constant to another type. The size of CST must be
1538 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1539
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]1540 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1541 <dd>Convert a floating point constant to the corresponding unsigned integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1542 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1543 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1544 of the same number of elements. If the value won't fit in the integer type,
1545 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1546
1547 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1548 <dd>Convert a floating point constant to the corresponding signed integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1549 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1550 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1551 of the same number of elements. If the value won't fit in the integer type,
1552 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1553
1554 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1555 <dd>Convert an unsigned integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1556 constant. TYPE must be a scalar or vector floating point type. CST must be of
1557 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1558 of the same number of elements. If the value won't fit in the floating point
1559 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1560
1561 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
1562 <dd>Convert a signed integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1563 constant. TYPE must be a scalar or vector floating point type. CST must be of
1564 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1565 of the same number of elements. If the value won't fit in the floating point
1566 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1567
1568 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1569 <dd>Convert a pointer typed constant to the corresponding integer constant
1570 TYPE must be an integer type. CST must be of pointer type. The CST value is
1571 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1572
1573 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1574 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1575 pointer type. CST must be of integer type. The CST value is zero extended,
1576 truncated, or unchanged to make it fit in a pointer size. This one is
1577 <i>really</i> dangerous!</dd>
1578
1579 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
1580 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1581 identical (same number of bits). The conversion is done as if the CST value
1582 was stored to memory and read back as TYPE. In other words, no bits change
1583 with this operator, just the type. This can be used for conversion of
1584 vector types to any other type, as long as they have the same bit width. For
1585 pointers it is only valid to cast to another pointer type.
1586 </dd>
1587
1588 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1589
1590 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1591 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1592 instruction, the index list may have zero or more indexes, which are required
1593 to make sense for the type of "CSTPTR".</dd>
1594
1595 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1596
1597 <dd>Perform the <a href="#i_select">select operation</a> on
1598 constants.</dd>
1599
1600 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1601 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1602
1603 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1604 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
1605
1606 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1607
1608 <dd>Perform the <a href="#i_extractelement">extractelement
1609 operation</a> on constants.
1610
1611 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1612
1613 <dd>Perform the <a href="#i_insertelement">insertelement
1614 operation</a> on constants.</dd>
1615
1616
1617 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1618
1619 <dd>Perform the <a href="#i_shufflevector">shufflevector
1620 operation</a> on constants.</dd>
1621
1622 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1623
1624 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1625 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
1626 binary</a> operations. The constraints on operands are the same as those for
1627 the corresponding instruction (e.g. no bitwise operations on floating point
1628 values are allowed).</dd>
1629</dl>
1630</div>
1631
1632<!-- *********************************************************************** -->
1633<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1634<!-- *********************************************************************** -->
1635
1636<!-- ======================================================================= -->
1637<div class="doc_subsection">
1638<a name="inlineasm">Inline Assembler Expressions</a>
1639</div>
1640
1641<div class="doc_text">
1642
1643<p>
1644LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1645Module-Level Inline Assembly</a>) through the use of a special value. This
1646value represents the inline assembler as a string (containing the instructions
1647to emit), a list of operand constraints (stored as a string), and a flag that
1648indicates whether or not the inline asm expression has side effects. An example
1649inline assembler expression is:
1650</p>
1651
1652<div class="doc_code">
1653<pre>
1654i32 (i32) asm "bswap $0", "=r,r"
1655</pre>
1656</div>
1657
1658<p>
1659Inline assembler expressions may <b>only</b> be used as the callee operand of
1660a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1661</p>
1662
1663<div class="doc_code">
1664<pre>
1665%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
1666</pre>
1667</div>
1668
1669<p>
1670Inline asms with side effects not visible in the constraint list must be marked
1671as having side effects. This is done through the use of the
1672'<tt>sideeffect</tt>' keyword, like so:
1673</p>
1674
1675<div class="doc_code">
1676<pre>
1677call void asm sideeffect "eieio", ""()
1678</pre>
1679</div>
1680
1681<p>TODO: The format of the asm and constraints string still need to be
1682documented here. Constraints on what can be done (e.g. duplication, moving, etc
1683need to be documented).
1684</p>
1685
1686</div>
1687
1688<!-- *********************************************************************** -->
1689<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1690<!-- *********************************************************************** -->
1691
1692<div class="doc_text">
1693
1694<p>The LLVM instruction set consists of several different
1695classifications of instructions: <a href="#terminators">terminator
1696instructions</a>, <a href="#binaryops">binary instructions</a>,
1697<a href="#bitwiseops">bitwise binary instructions</a>, <a
1698 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1699instructions</a>.</p>
1700
1701</div>
1702
1703<!-- ======================================================================= -->
1704<div class="doc_subsection"> <a name="terminators">Terminator
1705Instructions</a> </div>
1706
1707<div class="doc_text">
1708
1709<p>As mentioned <a href="#functionstructure">previously</a>, every
1710basic block in a program ends with a "Terminator" instruction, which
1711indicates which block should be executed after the current block is
1712finished. These terminator instructions typically yield a '<tt>void</tt>'
1713value: they produce control flow, not values (the one exception being
1714the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
1715<p>There are six different terminator instructions: the '<a
1716 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1717instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
1718the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1719 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1720 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
1721
1722</div>
1723
1724<!-- _______________________________________________________________________ -->
1725<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1726Instruction</a> </div>
1727<div class="doc_text">
1728<h5>Syntax:</h5>
1729<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
1730 ret void <i>; Return from void function</i>
1731</pre>
1732<h5>Overview:</h5>
1733<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1734value) from a function back to the caller.</p>
1735<p>There are two forms of the '<tt>ret</tt>' instruction: one that
1736returns a value and then causes control flow, and one that just causes
1737control flow to occur.</p>
1738<h5>Arguments:</h5>
1739<p>The '<tt>ret</tt>' instruction may return any '<a
1740 href="#t_firstclass">first class</a>' type. Notice that a function is
1741not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1742instruction inside of the function that returns a value that does not
1743match the return type of the function.</p>
1744<h5>Semantics:</h5>
1745<p>When the '<tt>ret</tt>' instruction is executed, control flow
1746returns back to the calling function's context. If the caller is a "<a
1747 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
1748the instruction after the call. If the caller was an "<a
1749 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1750at the beginning of the "normal" destination block. If the instruction
1751returns a value, that value shall set the call or invoke instruction's
1752return value.</p>
1753<h5>Example:</h5>
1754<pre> ret i32 5 <i>; Return an integer value of 5</i>
1755 ret void <i>; Return from a void function</i>
1756</pre>
1757</div>
1758<!-- _______________________________________________________________________ -->
1759<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
1760<div class="doc_text">
1761<h5>Syntax:</h5>
1762<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
1763</pre>
1764<h5>Overview:</h5>
1765<p>The '<tt>br</tt>' instruction is used to cause control flow to
1766transfer to a different basic block in the current function. There are
1767two forms of this instruction, corresponding to a conditional branch
1768and an unconditional branch.</p>
1769<h5>Arguments:</h5>
1770<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1771single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
1772unconditional form of the '<tt>br</tt>' instruction takes a single
1773'<tt>label</tt>' value as a target.</p>
1774<h5>Semantics:</h5>
1775<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
1776argument is evaluated. If the value is <tt>true</tt>, control flows
1777to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1778control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
1779<h5>Example:</h5>
1780<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
1781 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
1782</div>
1783<!-- _______________________________________________________________________ -->
1784<div class="doc_subsubsection">
1785 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1786</div>
1787
1788<div class="doc_text">
1789<h5>Syntax:</h5>
1790
1791<pre>
1792 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1793</pre>
1794
1795<h5>Overview:</h5>
1796
1797<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1798several different places. It is a generalization of the '<tt>br</tt>'
1799instruction, allowing a branch to occur to one of many possible
1800destinations.</p>
1801
1802
1803<h5>Arguments:</h5>
1804
1805<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1806comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1807an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1808table is not allowed to contain duplicate constant entries.</p>
1809
1810<h5>Semantics:</h5>
1811
1812<p>The <tt>switch</tt> instruction specifies a table of values and
1813destinations. When the '<tt>switch</tt>' instruction is executed, this
1814table is searched for the given value. If the value is found, control flow is
1815transfered to the corresponding destination; otherwise, control flow is
1816transfered to the default destination.</p>
1817
1818<h5>Implementation:</h5>
1819
1820<p>Depending on properties of the target machine and the particular
1821<tt>switch</tt> instruction, this instruction may be code generated in different
1822ways. For example, it could be generated as a series of chained conditional
1823branches or with a lookup table.</p>
1824
1825<h5>Example:</h5>
1826
1827<pre>
1828 <i>; Emulate a conditional br instruction</i>
1829 %Val = <a href="#i_zext">zext</a> i1 %value to i32
1830 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
1831
1832 <i>; Emulate an unconditional br instruction</i>
1833 switch i32 0, label %dest [ ]
1834
1835 <i>; Implement a jump table:</i>
1836 switch i32 %val, label %otherwise [ i32 0, label %onzero
1837 i32 1, label %onone
1838 i32 2, label %ontwo ]
1839</pre>
1840</div>
1841
1842<!-- _______________________________________________________________________ -->
1843<div class="doc_subsubsection">
1844 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1845</div>
1846
1847<div class="doc_text">
1848
1849<h5>Syntax:</h5>
1850
1851<pre>
1852 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1853 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
1854</pre>
1855
1856<h5>Overview:</h5>
1857
1858<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1859function, with the possibility of control flow transfer to either the
1860'<tt>normal</tt>' label or the
1861'<tt>exception</tt>' label. If the callee function returns with the
1862"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1863"normal" label. If the callee (or any indirect callees) returns with the "<a
1864href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1865continued at the dynamically nearest "exception" label.</p>
1866
1867<h5>Arguments:</h5>
1868
1869<p>This instruction requires several arguments:</p>
1870
1871<ol>
1872 <li>
1873 The optional "cconv" marker indicates which <a href="#callingconv">calling
1874 convention</a> the call should use. If none is specified, the call defaults
1875 to using C calling conventions.
1876 </li>
1877 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1878 function value being invoked. In most cases, this is a direct function
1879 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1880 an arbitrary pointer to function value.
1881 </li>
1882
1883 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1884 function to be invoked. </li>
1885
1886 <li>'<tt>function args</tt>': argument list whose types match the function
1887 signature argument types. If the function signature indicates the function
1888 accepts a variable number of arguments, the extra arguments can be
1889 specified. </li>
1890
1891 <li>'<tt>normal label</tt>': the label reached when the called function
1892 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1893
1894 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1895 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1896
1897</ol>
1898
1899<h5>Semantics:</h5>
1900
1901<p>This instruction is designed to operate as a standard '<tt><a
1902href="#i_call">call</a></tt>' instruction in most regards. The primary
1903difference is that it establishes an association with a label, which is used by
1904the runtime library to unwind the stack.</p>
1905
1906<p>This instruction is used in languages with destructors to ensure that proper
1907cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1908exception. Additionally, this is important for implementation of
1909'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1910
1911<h5>Example:</h5>
1912<pre>
1913 %retval = invoke i32 %Test(i32 15) to label %Continue
1914 unwind label %TestCleanup <i>; {i32}:retval set</i>
1915 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1916 unwind label %TestCleanup <i>; {i32}:retval set</i>
1917</pre>
1918</div>
1919
1920
1921<!-- _______________________________________________________________________ -->
1922
1923<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1924Instruction</a> </div>
1925
1926<div class="doc_text">
1927
1928<h5>Syntax:</h5>
1929<pre>
1930 unwind
1931</pre>
1932
1933<h5>Overview:</h5>
1934
1935<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1936at the first callee in the dynamic call stack which used an <a
1937href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1938primarily used to implement exception handling.</p>
1939
1940<h5>Semantics:</h5>
1941
1942<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1943immediately halt. The dynamic call stack is then searched for the first <a
1944href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1945execution continues at the "exceptional" destination block specified by the
1946<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1947dynamic call chain, undefined behavior results.</p>
1948</div>
1949
1950<!-- _______________________________________________________________________ -->
1951
1952<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1953Instruction</a> </div>
1954
1955<div class="doc_text">
1956
1957<h5>Syntax:</h5>
1958<pre>
1959 unreachable
1960</pre>
1961
1962<h5>Overview:</h5>
1963
1964<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1965instruction is used to inform the optimizer that a particular portion of the
1966code is not reachable. This can be used to indicate that the code after a
1967no-return function cannot be reached, and other facts.</p>
1968
1969<h5>Semantics:</h5>
1970
1971<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1972</div>
1973
1974
1975
1976<!-- ======================================================================= -->
1977<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
1978<div class="doc_text">
1979<p>Binary operators are used to do most of the computation in a
1980program. They require two operands, execute an operation on them, and
1981produce a single value. The operands might represent
1982multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
1983The result value of a binary operator is not
1984necessarily the same type as its operands.</p>
1985<p>There are several different binary operators:</p>
1986</div>
1987<!-- _______________________________________________________________________ -->
1988<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1989Instruction</a> </div>
1990<div class="doc_text">
1991<h5>Syntax:</h5>
1992<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1993</pre>
1994<h5>Overview:</h5>
1995<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
1996<h5>Arguments:</h5>
1997<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
1998 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1999 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2000Both arguments must have identical types.</p>
2001<h5>Semantics:</h5>
2002<p>The value produced is the integer or floating point sum of the two
2003operands.</p>
2004<h5>Example:</h5>
2005<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
2006</pre>
2007</div>
2008<!-- _______________________________________________________________________ -->
2009<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
2010Instruction</a> </div>
2011<div class="doc_text">
2012<h5>Syntax:</h5>
2013<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2014</pre>
2015<h5>Overview:</h5>
2016<p>The '<tt>sub</tt>' instruction returns the difference of its two
2017operands.</p>
2018<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
2019instruction present in most other intermediate representations.</p>
2020<h5>Arguments:</h5>
2021<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
2022 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2023values.
2024This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2025Both arguments must have identical types.</p>
2026<h5>Semantics:</h5>
2027<p>The value produced is the integer or floating point difference of
2028the two operands.</p>
2029<h5>Example:</h5>
2030<pre>
2031 &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2032 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2033</pre>
2034</div>
2035<!-- _______________________________________________________________________ -->
2036<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
2037Instruction</a> </div>
2038<div class="doc_text">
2039<h5>Syntax:</h5>
2040<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2041</pre>
2042<h5>Overview:</h5>
2043<p>The '<tt>mul</tt>' instruction returns the product of its two
2044operands.</p>
2045<h5>Arguments:</h5>
2046<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
2047 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2048values.
2049This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2050Both arguments must have identical types.</p>
2051<h5>Semantics:</h5>
2052<p>The value produced is the integer or floating point product of the
2053two operands.</p>
2054<p>Because the operands are the same width, the result of an integer
2055multiplication is the same whether the operands should be deemed unsigned or
2056signed.</p>
2057<h5>Example:</h5>
2058<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2059</pre>
2060</div>
2061<!-- _______________________________________________________________________ -->
2062<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2063</a></div>
2064<div class="doc_text">
2065<h5>Syntax:</h5>
2066<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2067</pre>
2068<h5>Overview:</h5>
2069<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2070operands.</p>
2071<h5>Arguments:</h5>
2072<p>The two arguments to the '<tt>udiv</tt>' instruction must be
2073<a href="#t_integer">integer</a> values. Both arguments must have identical
2074types. This instruction can also take <a href="#t_vector">vector</a> versions
2075of the values in which case the elements must be integers.</p>
2076<h5>Semantics:</h5>
2077<p>The value produced is the unsigned integer quotient of the two operands. This
2078instruction always performs an unsigned division operation, regardless of
2079whether the arguments are unsigned or not.</p>
2080<h5>Example:</h5>
2081<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2082</pre>
2083</div>
2084<!-- _______________________________________________________________________ -->
2085<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2086</a> </div>
2087<div class="doc_text">
2088<h5>Syntax:</h5>
2089<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2090</pre>
2091<h5>Overview:</h5>
2092<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2093operands.</p>
2094<h5>Arguments:</h5>
2095<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2096<a href="#t_integer">integer</a> values. Both arguments must have identical
2097types. This instruction can also take <a href="#t_vector">vector</a> versions
2098of the values in which case the elements must be integers.</p>
2099<h5>Semantics:</h5>
2100<p>The value produced is the signed integer quotient of the two operands. This
2101instruction always performs a signed division operation, regardless of whether
2102the arguments are signed or not.</p>
2103<h5>Example:</h5>
2104<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2105</pre>
2106</div>
2107<!-- _______________________________________________________________________ -->
2108<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2109Instruction</a> </div>
2110<div class="doc_text">
2111<h5>Syntax:</h5>
2112<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2113</pre>
2114<h5>Overview:</h5>
2115<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2116operands.</p>
2117<h5>Arguments:</h5>
2118<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2119<a href="#t_floating">floating point</a> values. Both arguments must have
2120identical types. This instruction can also take <a href="#t_vector">vector</a>
2121versions of floating point values.</p>
2122<h5>Semantics:</h5>
2123<p>The value produced is the floating point quotient of the two operands.</p>
2124<h5>Example:</h5>
2125<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2126</pre>
2127</div>
2128<!-- _______________________________________________________________________ -->
2129<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2130</div>
2131<div class="doc_text">
2132<h5>Syntax:</h5>
2133<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2134</pre>
2135<h5>Overview:</h5>
2136<p>The '<tt>urem</tt>' instruction returns the remainder from the
2137unsigned division of its two arguments.</p>
2138<h5>Arguments:</h5>
2139<p>The two arguments to the '<tt>urem</tt>' instruction must be
2140<a href="#t_integer">integer</a> values. Both arguments must have identical
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2141types. This instruction can also take <a href="#t_vector">vector</a> versions
2142of the values in which case the elements must be integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2143<h5>Semantics:</h5>
2144<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
2145This instruction always performs an unsigned division to get the remainder,
2146regardless of whether the arguments are unsigned or not.</p>
2147<h5>Example:</h5>
2148<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2149</pre>
2150
2151</div>
2152<!-- _______________________________________________________________________ -->
2153<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
2154Instruction</a> </div>
2155<div class="doc_text">
2156<h5>Syntax:</h5>
2157<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2158</pre>
2159<h5>Overview:</h5>
2160<p>The '<tt>srem</tt>' instruction returns the remainder from the
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2161signed division of its two operands. This instruction can also take
2162<a href="#t_vector">vector</a> versions of the values in which case
2163the elements must be integers.</p>
2164</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2165<h5>Arguments:</h5>
2166<p>The two arguments to the '<tt>srem</tt>' instruction must be
2167<a href="#t_integer">integer</a> values. Both arguments must have identical
2168types.</p>
2169<h5>Semantics:</h5>
2170<p>This instruction returns the <i>remainder</i> of a division (where the result
2171has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2172operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2173a value. For more information about the difference, see <a
2174 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2175Math Forum</a>. For a table of how this is implemented in various languages,
2176please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2177Wikipedia: modulo operation</a>.</p>
2178<h5>Example:</h5>
2179<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2180</pre>
2181
2182</div>
2183<!-- _______________________________________________________________________ -->
2184<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2185Instruction</a> </div>
2186<div class="doc_text">
2187<h5>Syntax:</h5>
2188<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2189</pre>
2190<h5>Overview:</h5>
2191<p>The '<tt>frem</tt>' instruction returns the remainder from the
2192division of its two operands.</p>
2193<h5>Arguments:</h5>
2194<p>The two arguments to the '<tt>frem</tt>' instruction must be
2195<a href="#t_floating">floating point</a> values. Both arguments must have
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2196identical types. This instruction can also take <a href="#t_vector">vector</a>
2197versions of floating point values.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2198<h5>Semantics:</h5>
2199<p>This instruction returns the <i>remainder</i> of a division.</p>
2200<h5>Example:</h5>
2201<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2202</pre>
2203</div>
2204
2205<!-- ======================================================================= -->
2206<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2207Operations</a> </div>
2208<div class="doc_text">
2209<p>Bitwise binary operators are used to do various forms of
2210bit-twiddling in a program. They are generally very efficient
2211instructions and can commonly be strength reduced from other
2212instructions. They require two operands, execute an operation on them,
2213and produce a single value. The resulting value of the bitwise binary
2214operators is always the same type as its first operand.</p>
2215</div>
2216
2217<!-- _______________________________________________________________________ -->
2218<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2219Instruction</a> </div>
2220<div class="doc_text">
2221<h5>Syntax:</h5>
2222<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2223</pre>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2224
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2225<h5>Overview:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2226
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2227<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2228the left a specified number of bits.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2229
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2230<h5>Arguments:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2231
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2232<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2233 href="#t_integer">integer</a> type.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2234
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2235<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2236
2237<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>. If
2238<tt>var2</tt> is (statically or dynamically) equal to or larger than the number
2239of bits in <tt>var1</tt>, the result is undefined.</p>
2240
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2241<h5>Example:</h5><pre>
2242 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2243 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2244 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2245 &lt;result&gt; = shl i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2246</pre>
2247</div>
2248<!-- _______________________________________________________________________ -->
2249<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2250Instruction</a> </div>
2251<div class="doc_text">
2252<h5>Syntax:</h5>
2253<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2254</pre>
2255
2256<h5>Overview:</h5>
2257<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2258operand shifted to the right a specified number of bits with zero fill.</p>
2259
2260<h5>Arguments:</h5>
2261<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2262<a href="#t_integer">integer</a> type.</p>
2263
2264<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2265
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2266<p>This instruction always performs a logical shift right operation. The most
2267significant bits of the result will be filled with zero bits after the
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2268shift. If <tt>var2</tt> is (statically or dynamically) equal to or larger than
2269the number of bits in <tt>var1</tt>, the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2270
2271<h5>Example:</h5>
2272<pre>
2273 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2274 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2275 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2276 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2277 &lt;result&gt; = lshr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2278</pre>
2279</div>
2280
2281<!-- _______________________________________________________________________ -->
2282<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2283Instruction</a> </div>
2284<div class="doc_text">
2285
2286<h5>Syntax:</h5>
2287<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2288</pre>
2289
2290<h5>Overview:</h5>
2291<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2292operand shifted to the right a specified number of bits with sign extension.</p>
2293
2294<h5>Arguments:</h5>
2295<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2296<a href="#t_integer">integer</a> type.</p>
2297
2298<h5>Semantics:</h5>
2299<p>This instruction always performs an arithmetic shift right operation,
2300The most significant bits of the result will be filled with the sign bit
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2301of <tt>var1</tt>. If <tt>var2</tt> is (statically or dynamically) equal to or
2302larger than the number of bits in <tt>var1</tt>, the result is undefined.
2303</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2304
2305<h5>Example:</h5>
2306<pre>
2307 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2308 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2309 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2310 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2311 &lt;result&gt; = ashr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2312</pre>
2313</div>
2314
2315<!-- _______________________________________________________________________ -->
2316<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2317Instruction</a> </div>
2318<div class="doc_text">
2319<h5>Syntax:</h5>
2320<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2321</pre>
2322<h5>Overview:</h5>
2323<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2324its two operands.</p>
2325<h5>Arguments:</h5>
2326<p>The two arguments to the '<tt>and</tt>' instruction must be <a
2327 href="#t_integer">integer</a> values. Both arguments must have
2328identical types.</p>
2329<h5>Semantics:</h5>
2330<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
2331<p> </p>
2332<div style="align: center">
2333<table border="1" cellspacing="0" cellpadding="4">
2334 <tbody>
2335 <tr>
2336 <td>In0</td>
2337 <td>In1</td>
2338 <td>Out</td>
2339 </tr>
2340 <tr>
2341 <td>0</td>
2342 <td>0</td>
2343 <td>0</td>
2344 </tr>
2345 <tr>
2346 <td>0</td>
2347 <td>1</td>
2348 <td>0</td>
2349 </tr>
2350 <tr>
2351 <td>1</td>
2352 <td>0</td>
2353 <td>0</td>
2354 </tr>
2355 <tr>
2356 <td>1</td>
2357 <td>1</td>
2358 <td>1</td>
2359 </tr>
2360 </tbody>
2361</table>
2362</div>
2363<h5>Example:</h5>
2364<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2365 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2366 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
2367</pre>
2368</div>
2369<!-- _______________________________________________________________________ -->
2370<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
2371<div class="doc_text">
2372<h5>Syntax:</h5>
2373<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2374</pre>
2375<h5>Overview:</h5>
2376<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2377or of its two operands.</p>
2378<h5>Arguments:</h5>
2379<p>The two arguments to the '<tt>or</tt>' instruction must be <a
2380 href="#t_integer">integer</a> values. Both arguments must have
2381identical types.</p>
2382<h5>Semantics:</h5>
2383<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
2384<p> </p>
2385<div style="align: center">
2386<table border="1" cellspacing="0" cellpadding="4">
2387 <tbody>
2388 <tr>
2389 <td>In0</td>
2390 <td>In1</td>
2391 <td>Out</td>
2392 </tr>
2393 <tr>
2394 <td>0</td>
2395 <td>0</td>
2396 <td>0</td>
2397 </tr>
2398 <tr>
2399 <td>0</td>
2400 <td>1</td>
2401 <td>1</td>
2402 </tr>
2403 <tr>
2404 <td>1</td>
2405 <td>0</td>
2406 <td>1</td>
2407 </tr>
2408 <tr>
2409 <td>1</td>
2410 <td>1</td>
2411 <td>1</td>
2412 </tr>
2413 </tbody>
2414</table>
2415</div>
2416<h5>Example:</h5>
2417<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2418 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2419 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
2420</pre>
2421</div>
2422<!-- _______________________________________________________________________ -->
2423<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2424Instruction</a> </div>
2425<div class="doc_text">
2426<h5>Syntax:</h5>
2427<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2428</pre>
2429<h5>Overview:</h5>
2430<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2431or of its two operands. The <tt>xor</tt> is used to implement the
2432"one's complement" operation, which is the "~" operator in C.</p>
2433<h5>Arguments:</h5>
2434<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
2435 href="#t_integer">integer</a> values. Both arguments must have
2436identical types.</p>
2437<h5>Semantics:</h5>
2438<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
2439<p> </p>
2440<div style="align: center">
2441<table border="1" cellspacing="0" cellpadding="4">
2442 <tbody>
2443 <tr>
2444 <td>In0</td>
2445 <td>In1</td>
2446 <td>Out</td>
2447 </tr>
2448 <tr>
2449 <td>0</td>
2450 <td>0</td>
2451 <td>0</td>
2452 </tr>
2453 <tr>
2454 <td>0</td>
2455 <td>1</td>
2456 <td>1</td>
2457 </tr>
2458 <tr>
2459 <td>1</td>
2460 <td>0</td>
2461 <td>1</td>
2462 </tr>
2463 <tr>
2464 <td>1</td>
2465 <td>1</td>
2466 <td>0</td>
2467 </tr>
2468 </tbody>
2469</table>
2470</div>
2471<p> </p>
2472<h5>Example:</h5>
2473<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2474 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2475 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2476 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
2477</pre>
2478</div>
2479
2480<!-- ======================================================================= -->
2481<div class="doc_subsection">
2482 <a name="vectorops">Vector Operations</a>
2483</div>
2484
2485<div class="doc_text">
2486
2487<p>LLVM supports several instructions to represent vector operations in a
2488target-independent manner. These instructions cover the element-access and
2489vector-specific operations needed to process vectors effectively. While LLVM
2490does directly support these vector operations, many sophisticated algorithms
2491will want to use target-specific intrinsics to take full advantage of a specific
2492target.</p>
2493
2494</div>
2495
2496<!-- _______________________________________________________________________ -->
2497<div class="doc_subsubsection">
2498 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2499</div>
2500
2501<div class="doc_text">
2502
2503<h5>Syntax:</h5>
2504
2505<pre>
2506 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2507</pre>
2508
2509<h5>Overview:</h5>
2510
2511<p>
2512The '<tt>extractelement</tt>' instruction extracts a single scalar
2513element from a vector at a specified index.
2514</p>
2515
2516
2517<h5>Arguments:</h5>
2518
2519<p>
2520The first operand of an '<tt>extractelement</tt>' instruction is a
2521value of <a href="#t_vector">vector</a> type. The second operand is
2522an index indicating the position from which to extract the element.
2523The index may be a variable.</p>
2524
2525<h5>Semantics:</h5>
2526
2527<p>
2528The result is a scalar of the same type as the element type of
2529<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2530<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2531results are undefined.
2532</p>
2533
2534<h5>Example:</h5>
2535
2536<pre>
2537 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
2538</pre>
2539</div>
2540
2541
2542<!-- _______________________________________________________________________ -->
2543<div class="doc_subsubsection">
2544 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2545</div>
2546
2547<div class="doc_text">
2548
2549<h5>Syntax:</h5>
2550
2551<pre>
2552 &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>
2553</pre>
2554
2555<h5>Overview:</h5>
2556
2557<p>
2558The '<tt>insertelement</tt>' instruction inserts a scalar
2559element into a vector at a specified index.
2560</p>
2561
2562
2563<h5>Arguments:</h5>
2564
2565<p>
2566The first operand of an '<tt>insertelement</tt>' instruction is a
2567value of <a href="#t_vector">vector</a> type. The second operand is a
2568scalar value whose type must equal the element type of the first
2569operand. The third operand is an index indicating the position at
2570which to insert the value. The index may be a variable.</p>
2571
2572<h5>Semantics:</h5>
2573
2574<p>
2575The result is a vector of the same type as <tt>val</tt>. Its
2576element values are those of <tt>val</tt> except at position
2577<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2578exceeds the length of <tt>val</tt>, the results are undefined.
2579</p>
2580
2581<h5>Example:</h5>
2582
2583<pre>
2584 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
2585</pre>
2586</div>
2587
2588<!-- _______________________________________________________________________ -->
2589<div class="doc_subsubsection">
2590 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2591</div>
2592
2593<div class="doc_text">
2594
2595<h5>Syntax:</h5>
2596
2597<pre>
2598 &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>
2599</pre>
2600
2601<h5>Overview:</h5>
2602
2603<p>
2604The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2605from two input vectors, returning a vector of the same type.
2606</p>
2607
2608<h5>Arguments:</h5>
2609
2610<p>
2611The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2612with types that match each other and types that match the result of the
2613instruction. The third argument is a shuffle mask, which has the same number
2614of elements as the other vector type, but whose element type is always 'i32'.
2615</p>
2616
2617<p>
2618The shuffle mask operand is required to be a constant vector with either
2619constant integer or undef values.
2620</p>
2621
2622<h5>Semantics:</h5>
2623
2624<p>
2625The elements of the two input vectors are numbered from left to right across
2626both of the vectors. The shuffle mask operand specifies, for each element of
2627the result vector, which element of the two input registers the result element
2628gets. The element selector may be undef (meaning "don't care") and the second
2629operand may be undef if performing a shuffle from only one vector.
2630</p>
2631
2632<h5>Example:</h5>
2633
2634<pre>
2635 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2636 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2637 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2638 &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.
2639</pre>
2640</div>
2641
2642
2643<!-- ======================================================================= -->
2644<div class="doc_subsection">
2645 <a name="memoryops">Memory Access and Addressing Operations</a>
2646</div>
2647
2648<div class="doc_text">
2649
2650<p>A key design point of an SSA-based representation is how it
2651represents memory. In LLVM, no memory locations are in SSA form, which
2652makes things very simple. This section describes how to read, write,
2653allocate, and free memory in LLVM.</p>
2654
2655</div>
2656
2657<!-- _______________________________________________________________________ -->
2658<div class="doc_subsubsection">
2659 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2660</div>
2661
2662<div class="doc_text">
2663
2664<h5>Syntax:</h5>
2665
2666<pre>
2667 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2668</pre>
2669
2670<h5>Overview:</h5>
2671
2672<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2673heap and returns a pointer to it.</p>
2674
2675<h5>Arguments:</h5>
2676
2677<p>The '<tt>malloc</tt>' instruction allocates
2678<tt>sizeof(&lt;type&gt;)*NumElements</tt>
2679bytes of memory from the operating system and returns a pointer of the
2680appropriate type to the program. If "NumElements" is specified, it is the
2681number of elements allocated. If an alignment is specified, the value result
2682of the allocation is guaranteed to be aligned to at least that boundary. If
2683not specified, or if zero, the target can choose to align the allocation on any
2684convenient boundary.</p>
2685
2686<p>'<tt>type</tt>' must be a sized type.</p>
2687
2688<h5>Semantics:</h5>
2689
2690<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2691a pointer is returned.</p>
2692
2693<h5>Example:</h5>
2694
2695<pre>
2696 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
2697
2698 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2699 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2700 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2701 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2702 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
2703</pre>
2704</div>
2705
2706<!-- _______________________________________________________________________ -->
2707<div class="doc_subsubsection">
2708 <a name="i_free">'<tt>free</tt>' Instruction</a>
2709</div>
2710
2711<div class="doc_text">
2712
2713<h5>Syntax:</h5>
2714
2715<pre>
2716 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
2717</pre>
2718
2719<h5>Overview:</h5>
2720
2721<p>The '<tt>free</tt>' instruction returns memory back to the unused
2722memory heap to be reallocated in the future.</p>
2723
2724<h5>Arguments:</h5>
2725
2726<p>'<tt>value</tt>' shall be a pointer value that points to a value
2727that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2728instruction.</p>
2729
2730<h5>Semantics:</h5>
2731
2732<p>Access to the memory pointed to by the pointer is no longer defined
2733after this instruction executes.</p>
2734
2735<h5>Example:</h5>
2736
2737<pre>
2738 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2739 free [4 x i8]* %array
2740</pre>
2741</div>
2742
2743<!-- _______________________________________________________________________ -->
2744<div class="doc_subsubsection">
2745 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2746</div>
2747
2748<div class="doc_text">
2749
2750<h5>Syntax:</h5>
2751
2752<pre>
2753 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2754</pre>
2755
2756<h5>Overview:</h5>
2757
2758<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
2759currently executing function, to be automatically released when this function
2760returns to its caller.</p>
2761
2762<h5>Arguments:</h5>
2763
2764<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
2765bytes of memory on the runtime stack, returning a pointer of the
2766appropriate type to the program. If "NumElements" is specified, it is the
2767number of elements allocated. If an alignment is specified, the value result
2768of the allocation is guaranteed to be aligned to at least that boundary. If
2769not specified, or if zero, the target can choose to align the allocation on any
2770convenient boundary.</p>
2771
2772<p>'<tt>type</tt>' may be any sized type.</p>
2773
2774<h5>Semantics:</h5>
2775
2776<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
2777memory is automatically released when the function returns. The '<tt>alloca</tt>'
2778instruction is commonly used to represent automatic variables that must
2779have an address available. When the function returns (either with the <tt><a
2780 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
2781instructions), the memory is reclaimed.</p>
2782
2783<h5>Example:</h5>
2784
2785<pre>
2786 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2787 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2788 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2789 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
2790</pre>
2791</div>
2792
2793<!-- _______________________________________________________________________ -->
2794<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2795Instruction</a> </div>
2796<div class="doc_text">
2797<h5>Syntax:</h5>
2798<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>
2799<h5>Overview:</h5>
2800<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
2801<h5>Arguments:</h5>
2802<p>The argument to the '<tt>load</tt>' instruction specifies the memory
2803address from which to load. The pointer must point to a <a
2804 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
2805marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
2806the number or order of execution of this <tt>load</tt> with other
2807volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2808instructions. </p>
2809<h5>Semantics:</h5>
2810<p>The location of memory pointed to is loaded.</p>
2811<h5>Examples:</h5>
2812<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
2813 <a
2814 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2815 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
2816</pre>
2817</div>
2818<!-- _______________________________________________________________________ -->
2819<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2820Instruction</a> </div>
2821<div class="doc_text">
2822<h5>Syntax:</h5>
2823<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2824 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2825</pre>
2826<h5>Overview:</h5>
2827<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
2828<h5>Arguments:</h5>
2829<p>There are two arguments to the '<tt>store</tt>' instruction: a value
2830to store and an address at which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
2831operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
2832operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
2833optimizer is not allowed to modify the number or order of execution of
2834this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2835 href="#i_store">store</a></tt> instructions.</p>
2836<h5>Semantics:</h5>
2837<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2838at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
2839<h5>Example:</h5>
2840<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Bill Wendling63ffa142007-10-22 05:10:05 +0000[diff] [blame]2841 store i32 3, i32* %ptr <i>; yields {void}</i>
2842 %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]2843</pre>
2844</div>
2845
2846<!-- _______________________________________________________________________ -->
2847<div class="doc_subsubsection">
2848 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2849</div>
2850
2851<div class="doc_text">
2852<h5>Syntax:</h5>
2853<pre>
2854 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2855</pre>
2856
2857<h5>Overview:</h5>
2858
2859<p>
2860The '<tt>getelementptr</tt>' instruction is used to get the address of a
2861subelement of an aggregate data structure.</p>
2862
2863<h5>Arguments:</h5>
2864
2865<p>This instruction takes a list of integer operands that indicate what
2866elements of the aggregate object to index to. The actual types of the arguments
2867provided depend on the type of the first pointer argument. The
2868'<tt>getelementptr</tt>' instruction is used to index down through the type
2869levels of a structure or to a specific index in an array. When indexing into a
2870structure, only <tt>i32</tt> integer constants are allowed. When indexing
2871into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2872be sign extended to 64-bit values.</p>
2873
2874<p>For example, let's consider a C code fragment and how it gets
2875compiled to LLVM:</p>
2876
2877<div class="doc_code">
2878<pre>
2879struct RT {
2880 char A;
2881 int B[10][20];
2882 char C;
2883};
2884struct ST {
2885 int X;
2886 double Y;
2887 struct RT Z;
2888};
2889
2890int *foo(struct ST *s) {
2891 return &amp;s[1].Z.B[5][13];
2892}
2893</pre>
2894</div>
2895
2896<p>The LLVM code generated by the GCC frontend is:</p>
2897
2898<div class="doc_code">
2899<pre>
2900%RT = type { i8 , [10 x [20 x i32]], i8 }
2901%ST = type { i32, double, %RT }
2902
2903define i32* %foo(%ST* %s) {
2904entry:
2905 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2906 ret i32* %reg
2907}
2908</pre>
2909</div>
2910
2911<h5>Semantics:</h5>
2912
2913<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
2914on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
2915and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
2916<a href="#t_integer">integer</a> type but the value will always be sign extended
2917to 64-bits. <a href="#t_struct">Structure</a> types require <tt>i32</tt>
2918<b>constants</b>.</p>
2919
2920<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
2921type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
2922}</tt>' type, a structure. The second index indexes into the third element of
2923the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2924i8 }</tt>' type, another structure. The third index indexes into the second
2925element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
2926array. The two dimensions of the array are subscripted into, yielding an
2927'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2928to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
2929
2930<p>Note that it is perfectly legal to index partially through a
2931structure, returning a pointer to an inner element. Because of this,
2932the LLVM code for the given testcase is equivalent to:</p>
2933
2934<pre>
2935 define i32* %foo(%ST* %s) {
2936 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2937 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2938 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2939 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2940 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2941 ret i32* %t5
2942 }
2943</pre>
2944
2945<p>Note that it is undefined to access an array out of bounds: array and
2946pointer indexes must always be within the defined bounds of the array type.
2947The one exception for this rules is zero length arrays. These arrays are
2948defined to be accessible as variable length arrays, which requires access
2949beyond the zero'th element.</p>
2950
2951<p>The getelementptr instruction is often confusing. For some more insight
2952into how it works, see <a href="GetElementPtr.html">the getelementptr
2953FAQ</a>.</p>
2954
2955<h5>Example:</h5>
2956
2957<pre>
2958 <i>; yields [12 x i8]*:aptr</i>
2959 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
2960</pre>
2961</div>
2962
2963<!-- ======================================================================= -->
2964<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
2965</div>
2966<div class="doc_text">
2967<p>The instructions in this category are the conversion instructions (casting)
2968which all take a single operand and a type. They perform various bit conversions
2969on the operand.</p>
2970</div>
2971
2972<!-- _______________________________________________________________________ -->
2973<div class="doc_subsubsection">
2974 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2975</div>
2976<div class="doc_text">
2977
2978<h5>Syntax:</h5>
2979<pre>
2980 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2981</pre>
2982
2983<h5>Overview:</h5>
2984<p>
2985The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2986</p>
2987
2988<h5>Arguments:</h5>
2989<p>
2990The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2991be an <a href="#t_integer">integer</a> type, and a type that specifies the size
2992and type of the result, which must be an <a href="#t_integer">integer</a>
2993type. The bit size of <tt>value</tt> must be larger than the bit size of
2994<tt>ty2</tt>. Equal sized types are not allowed.</p>
2995
2996<h5>Semantics:</h5>
2997<p>
2998The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
2999and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
3000larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
3001It will always truncate bits.</p>
3002
3003<h5>Example:</h5>
3004<pre>
3005 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
3006 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
3007 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
3008</pre>
3009</div>
3010
3011<!-- _______________________________________________________________________ -->
3012<div class="doc_subsubsection">
3013 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3014</div>
3015<div class="doc_text">
3016
3017<h5>Syntax:</h5>
3018<pre>
3019 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3020</pre>
3021
3022<h5>Overview:</h5>
3023<p>The '<tt>zext</tt>' instruction zero extends its operand to type
3024<tt>ty2</tt>.</p>
3025
3026
3027<h5>Arguments:</h5>
3028<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3029<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3030also be of <a href="#t_integer">integer</a> type. The bit size of the
3031<tt>value</tt> must be smaller than the bit size of the destination type,
3032<tt>ty2</tt>.</p>
3033
3034<h5>Semantics:</h5>
3035<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3036bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3037
3038<p>When zero extending from i1, the result will always be either 0 or 1.</p>
3039
3040<h5>Example:</h5>
3041<pre>
3042 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3043 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3044</pre>
3045</div>
3046
3047<!-- _______________________________________________________________________ -->
3048<div class="doc_subsubsection">
3049 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3050</div>
3051<div class="doc_text">
3052
3053<h5>Syntax:</h5>
3054<pre>
3055 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3056</pre>
3057
3058<h5>Overview:</h5>
3059<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3060
3061<h5>Arguments:</h5>
3062<p>
3063The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3064<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3065also be of <a href="#t_integer">integer</a> type. The bit size of the
3066<tt>value</tt> must be smaller than the bit size of the destination type,
3067<tt>ty2</tt>.</p>
3068
3069<h5>Semantics:</h5>
3070<p>
3071The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3072bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3073the type <tt>ty2</tt>.</p>
3074
3075<p>When sign extending from i1, the extension always results in -1 or 0.</p>
3076
3077<h5>Example:</h5>
3078<pre>
3079 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3080 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3081</pre>
3082</div>
3083
3084<!-- _______________________________________________________________________ -->
3085<div class="doc_subsubsection">
3086 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3087</div>
3088
3089<div class="doc_text">
3090
3091<h5>Syntax:</h5>
3092
3093<pre>
3094 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3095</pre>
3096
3097<h5>Overview:</h5>
3098<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
3099<tt>ty2</tt>.</p>
3100
3101
3102<h5>Arguments:</h5>
3103<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
3104 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
3105cast it to. The size of <tt>value</tt> must be larger than the size of
3106<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
3107<i>no-op cast</i>.</p>
3108
3109<h5>Semantics:</h5>
3110<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
3111<a href="#t_floating">floating point</a> type to a smaller
3112<a href="#t_floating">floating point</a> type. If the value cannot fit within
3113the destination type, <tt>ty2</tt>, then the results are undefined.</p>
3114
3115<h5>Example:</h5>
3116<pre>
3117 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
3118 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
3119</pre>
3120</div>
3121
3122<!-- _______________________________________________________________________ -->
3123<div class="doc_subsubsection">
3124 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
3125</div>
3126<div class="doc_text">
3127
3128<h5>Syntax:</h5>
3129<pre>
3130 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3131</pre>
3132
3133<h5>Overview:</h5>
3134<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
3135floating point value.</p>
3136
3137<h5>Arguments:</h5>
3138<p>The '<tt>fpext</tt>' instruction takes a
3139<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
3140and a <a href="#t_floating">floating point</a> type to cast it to. The source
3141type must be smaller than the destination type.</p>
3142
3143<h5>Semantics:</h5>
3144<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
3145<a href="#t_floating">floating point</a> type to a larger
3146<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
3147used to make a <i>no-op cast</i> because it always changes bits. Use
3148<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
3149
3150<h5>Example:</h5>
3151<pre>
3152 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
3153 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
3154</pre>
3155</div>
3156
3157<!-- _______________________________________________________________________ -->
3158<div class="doc_subsubsection">
3159 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
3160</div>
3161<div class="doc_text">
3162
3163<h5>Syntax:</h5>
3164<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3165 &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]3166</pre>
3167
3168<h5>Overview:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3169<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3170unsigned integer equivalent of type <tt>ty2</tt>.
3171</p>
3172
3173<h5>Arguments:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3174<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]3175scalar or vector <a href="#t_floating">floating point</a> value, and a type
3176to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3177type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3178vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3179
3180<h5>Semantics:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3181<p> The '<tt>fptoui</tt>' instruction converts its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3182<a href="#t_floating">floating point</a> operand into the nearest (rounding
3183towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3184the results are undefined.</p>
3185
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3186<h5>Example:</h5>
3187<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3188 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3189 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3190 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3191</pre>
3192</div>
3193
3194<!-- _______________________________________________________________________ -->
3195<div class="doc_subsubsection">
3196 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
3197</div>
3198<div class="doc_text">
3199
3200<h5>Syntax:</h5>
3201<pre>
3202 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3203</pre>
3204
3205<h5>Overview:</h5>
3206<p>The '<tt>fptosi</tt>' instruction converts
3207<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
3208</p>
3209
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3210<h5>Arguments:</h5>
3211<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]3212scalar or vector <a href="#t_floating">floating point</a> value, and a type
3213to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3214type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3215vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3216
3217<h5>Semantics:</h5>
3218<p>The '<tt>fptosi</tt>' instruction converts its
3219<a href="#t_floating">floating point</a> operand into the nearest (rounding
3220towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3221the results are undefined.</p>
3222
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3223<h5>Example:</h5>
3224<pre>
3225 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3226 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3227 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
3228</pre>
3229</div>
3230
3231<!-- _______________________________________________________________________ -->
3232<div class="doc_subsubsection">
3233 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
3234</div>
3235<div class="doc_text">
3236
3237<h5>Syntax:</h5>
3238<pre>
3239 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3240</pre>
3241
3242<h5>Overview:</h5>
3243<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
3244integer and converts that value to the <tt>ty2</tt> type.</p>
3245
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3246<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3247<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
3248scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3249to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3250type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3251floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3252
3253<h5>Semantics:</h5>
3254<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
3255integer quantity and converts it to the corresponding floating point value. If
3256the value cannot fit in the floating point value, the results are undefined.</p>
3257
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3258<h5>Example:</h5>
3259<pre>
3260 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3261 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
3262</pre>
3263</div>
3264
3265<!-- _______________________________________________________________________ -->
3266<div class="doc_subsubsection">
3267 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
3268</div>
3269<div class="doc_text">
3270
3271<h5>Syntax:</h5>
3272<pre>
3273 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3274</pre>
3275
3276<h5>Overview:</h5>
3277<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
3278integer and converts that value to the <tt>ty2</tt> type.</p>
3279
3280<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3281<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
3282scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3283to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3284type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3285floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3286
3287<h5>Semantics:</h5>
3288<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
3289integer quantity and converts it to the corresponding floating point value. If
3290the value cannot fit in the floating point value, the results are undefined.</p>
3291
3292<h5>Example:</h5>
3293<pre>
3294 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3295 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
3296</pre>
3297</div>
3298
3299<!-- _______________________________________________________________________ -->
3300<div class="doc_subsubsection">
3301 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3302</div>
3303<div class="doc_text">
3304
3305<h5>Syntax:</h5>
3306<pre>
3307 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3308</pre>
3309
3310<h5>Overview:</h5>
3311<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3312the integer type <tt>ty2</tt>.</p>
3313
3314<h5>Arguments:</h5>
3315<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3316must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
3317<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3318
3319<h5>Semantics:</h5>
3320<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3321<tt>ty2</tt> by interpreting the pointer value as an integer and either
3322truncating or zero extending that value to the size of the integer type. If
3323<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3324<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3325are the same size, then nothing is done (<i>no-op cast</i>) other than a type
3326change.</p>
3327
3328<h5>Example:</h5>
3329<pre>
3330 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
3331 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
3332</pre>
3333</div>
3334
3335<!-- _______________________________________________________________________ -->
3336<div class="doc_subsubsection">
3337 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3338</div>
3339<div class="doc_text">
3340
3341<h5>Syntax:</h5>
3342<pre>
3343 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3344</pre>
3345
3346<h5>Overview:</h5>
3347<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3348a pointer type, <tt>ty2</tt>.</p>
3349
3350<h5>Arguments:</h5>
3351<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
3352value to cast, and a type to cast it to, which must be a
3353<a href="#t_pointer">pointer</a> type.
3354
3355<h5>Semantics:</h5>
3356<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3357<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3358the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3359size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3360the size of a pointer then a zero extension is done. If they are the same size,
3361nothing is done (<i>no-op cast</i>).</p>
3362
3363<h5>Example:</h5>
3364<pre>
3365 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
3366 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
3367 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
3368</pre>
3369</div>
3370
3371<!-- _______________________________________________________________________ -->
3372<div class="doc_subsubsection">
3373 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
3374</div>
3375<div class="doc_text">
3376
3377<h5>Syntax:</h5>
3378<pre>
3379 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3380</pre>
3381
3382<h5>Overview:</h5>
3383<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3384<tt>ty2</tt> without changing any bits.</p>
3385
3386<h5>Arguments:</h5>
3387<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
3388a first class value, and a type to cast it to, which must also be a <a
3389 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
3390and the destination type, <tt>ty2</tt>, must be identical. If the source
3391type is a pointer, the destination type must also be a pointer.</p>
3392
3393<h5>Semantics:</h5>
3394<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3395<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3396this conversion. The conversion is done as if the <tt>value</tt> had been
3397stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3398converted to other pointer types with this instruction. To convert pointers to
3399other types, use the <a href="#i_inttoptr">inttoptr</a> or
3400<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
3401
3402<h5>Example:</h5>
3403<pre>
3404 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3405 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3406 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
3407</pre>
3408</div>
3409
3410<!-- ======================================================================= -->
3411<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3412<div class="doc_text">
3413<p>The instructions in this category are the "miscellaneous"
3414instructions, which defy better classification.</p>
3415</div>
3416
3417<!-- _______________________________________________________________________ -->
3418<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3419</div>
3420<div class="doc_text">
3421<h5>Syntax:</h5>
3422<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3423</pre>
3424<h5>Overview:</h5>
3425<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3426of its two integer operands.</p>
3427<h5>Arguments:</h5>
3428<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3429the condition code indicating the kind of comparison to perform. It is not
3430a value, just a keyword. The possible condition code are:
3431<ol>
3432 <li><tt>eq</tt>: equal</li>
3433 <li><tt>ne</tt>: not equal </li>
3434 <li><tt>ugt</tt>: unsigned greater than</li>
3435 <li><tt>uge</tt>: unsigned greater or equal</li>
3436 <li><tt>ult</tt>: unsigned less than</li>
3437 <li><tt>ule</tt>: unsigned less or equal</li>
3438 <li><tt>sgt</tt>: signed greater than</li>
3439 <li><tt>sge</tt>: signed greater or equal</li>
3440 <li><tt>slt</tt>: signed less than</li>
3441 <li><tt>sle</tt>: signed less or equal</li>
3442</ol>
3443<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
3444<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
3445<h5>Semantics:</h5>
3446<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3447the condition code given as <tt>cond</tt>. The comparison performed always
3448yields a <a href="#t_primitive">i1</a> result, as follows:
3449<ol>
3450 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3451 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3452 </li>
3453 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3454 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3455 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3456 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3457 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3458 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3459 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3460 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3461 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3462 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3463 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3464 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3465 <li><tt>sge</tt>: interprets the operands as signed values and yields
3466 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3467 <li><tt>slt</tt>: interprets the operands as signed values and yields
3468 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3469 <li><tt>sle</tt>: interprets the operands as signed values and yields
3470 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3471</ol>
3472<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3473values are compared as if they were integers.</p>
3474
3475<h5>Example:</h5>
3476<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3477 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3478 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3479 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3480 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3481 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
3482</pre>
3483</div>
3484
3485<!-- _______________________________________________________________________ -->
3486<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3487</div>
3488<div class="doc_text">
3489<h5>Syntax:</h5>
3490<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3491</pre>
3492<h5>Overview:</h5>
3493<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3494of its floating point operands.</p>
3495<h5>Arguments:</h5>
3496<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3497the condition code indicating the kind of comparison to perform. It is not
3498a value, just a keyword. The possible condition code are:
3499<ol>
3500 <li><tt>false</tt>: no comparison, always returns false</li>
3501 <li><tt>oeq</tt>: ordered and equal</li>
3502 <li><tt>ogt</tt>: ordered and greater than </li>
3503 <li><tt>oge</tt>: ordered and greater than or equal</li>
3504 <li><tt>olt</tt>: ordered and less than </li>
3505 <li><tt>ole</tt>: ordered and less than or equal</li>
3506 <li><tt>one</tt>: ordered and not equal</li>
3507 <li><tt>ord</tt>: ordered (no nans)</li>
3508 <li><tt>ueq</tt>: unordered or equal</li>
3509 <li><tt>ugt</tt>: unordered or greater than </li>
3510 <li><tt>uge</tt>: unordered or greater than or equal</li>
3511 <li><tt>ult</tt>: unordered or less than </li>
3512 <li><tt>ule</tt>: unordered or less than or equal</li>
3513 <li><tt>une</tt>: unordered or not equal</li>
3514 <li><tt>uno</tt>: unordered (either nans)</li>
3515 <li><tt>true</tt>: no comparison, always returns true</li>
3516</ol>
3517<p><i>Ordered</i> means that neither operand is a QNAN while
3518<i>unordered</i> means that either operand may be a QNAN.</p>
3519<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3520<a href="#t_floating">floating point</a> typed. They must have identical
3521types.</p>
3522<h5>Semantics:</h5>
3523<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3524the condition code given as <tt>cond</tt>. The comparison performed always
3525yields a <a href="#t_primitive">i1</a> result, as follows:
3526<ol>
3527 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
3528 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3529 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3530 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3531 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
3532 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3533 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3534 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3535 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3536 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3537 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3538 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3539 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3540 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3541 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
3542 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3543 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
3544 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3545 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
3546 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3547 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
3548 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3549 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
3550 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3551 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
3552 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3553 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
3554 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3555</ol>
3556
3557<h5>Example:</h5>
3558<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3559 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3560 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3561 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3562</pre>
3563</div>
3564
3565<!-- _______________________________________________________________________ -->
3566<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3567Instruction</a> </div>
3568<div class="doc_text">
3569<h5>Syntax:</h5>
3570<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3571<h5>Overview:</h5>
3572<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3573the SSA graph representing the function.</p>
3574<h5>Arguments:</h5>
3575<p>The type of the incoming values is specified with the first type
3576field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3577as arguments, with one pair for each predecessor basic block of the
3578current block. Only values of <a href="#t_firstclass">first class</a>
3579type may be used as the value arguments to the PHI node. Only labels
3580may be used as the label arguments.</p>
3581<p>There must be no non-phi instructions between the start of a basic
3582block and the PHI instructions: i.e. PHI instructions must be first in
3583a basic block.</p>
3584<h5>Semantics:</h5>
3585<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
3586specified by the pair corresponding to the predecessor basic block that executed
3587just prior to the current block.</p>
3588<h5>Example:</h5>
3589<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>
3590</div>
3591
3592<!-- _______________________________________________________________________ -->
3593<div class="doc_subsubsection">
3594 <a name="i_select">'<tt>select</tt>' Instruction</a>
3595</div>
3596
3597<div class="doc_text">
3598
3599<h5>Syntax:</h5>
3600
3601<pre>
3602 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
3603</pre>
3604
3605<h5>Overview:</h5>
3606
3607<p>
3608The '<tt>select</tt>' instruction is used to choose one value based on a
3609condition, without branching.
3610</p>
3611
3612
3613<h5>Arguments:</h5>
3614
3615<p>
3616The '<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.
3617</p>
3618
3619<h5>Semantics:</h5>
3620
3621<p>
3622If the boolean condition evaluates to true, the instruction returns the first
3623value argument; otherwise, it returns the second value argument.
3624</p>
3625
3626<h5>Example:</h5>
3627
3628<pre>
3629 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
3630</pre>
3631</div>
3632
3633
3634<!-- _______________________________________________________________________ -->
3635<div class="doc_subsubsection">
3636 <a name="i_call">'<tt>call</tt>' Instruction</a>
3637</div>
3638
3639<div class="doc_text">
3640
3641<h5>Syntax:</h5>
3642<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3643 &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]3644</pre>
3645
3646<h5>Overview:</h5>
3647
3648<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
3649
3650<h5>Arguments:</h5>
3651
3652<p>This instruction requires several arguments:</p>
3653
3654<ol>
3655 <li>
3656 <p>The optional "tail" marker indicates whether the callee function accesses
3657 any allocas or varargs in the caller. If the "tail" marker is present, the
3658 function call is eligible for tail call optimization. Note that calls may
3659 be marked "tail" even if they do not occur before a <a
3660 href="#i_ret"><tt>ret</tt></a> instruction.
3661 </li>
3662 <li>
3663 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
3664 convention</a> the call should use. If none is specified, the call defaults
3665 to using C calling conventions.
3666 </li>
3667 <li>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3668 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
3669 the type of the return value. Functions that return no value are marked
3670 <tt><a href="#t_void">void</a></tt>.</p>
3671 </li>
3672 <li>
3673 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
3674 value being invoked. The argument types must match the types implied by
3675 this signature. This type can be omitted if the function is not varargs
3676 and if the function type does not return a pointer to a function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3677 </li>
3678 <li>
3679 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3680 be invoked. In most cases, this is a direct function invocation, but
3681 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
3682 to function value.</p>
3683 </li>
3684 <li>
3685 <p>'<tt>function args</tt>': argument list whose types match the
3686 function signature argument types. All arguments must be of
3687 <a href="#t_firstclass">first class</a> type. If the function signature
3688 indicates the function accepts a variable number of arguments, the extra
3689 arguments can be specified.</p>
3690 </li>
3691</ol>
3692
3693<h5>Semantics:</h5>
3694
3695<p>The '<tt>call</tt>' instruction is used to cause control flow to
3696transfer to a specified function, with its incoming arguments bound to
3697the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3698instruction in the called function, control flow continues with the
3699instruction after the function call, and the return value of the
3700function is bound to the result argument. This is a simpler case of
3701the <a href="#i_invoke">invoke</a> instruction.</p>
3702
3703<h5>Example:</h5>
3704
3705<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3706 %retval = call i32 @test(i32 %argc)
3707 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42);
3708 %X = tail call i32 @foo()
3709 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo()
3710 %Z = call void %foo(i8 97 signext)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3711</pre>
3712
3713</div>
3714
3715<!-- _______________________________________________________________________ -->
3716<div class="doc_subsubsection">
3717 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
3718</div>
3719
3720<div class="doc_text">
3721
3722<h5>Syntax:</h5>
3723
3724<pre>
3725 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
3726</pre>
3727
3728<h5>Overview:</h5>
3729
3730<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
3731the "variable argument" area of a function call. It is used to implement the
3732<tt>va_arg</tt> macro in C.</p>
3733
3734<h5>Arguments:</h5>
3735
3736<p>This instruction takes a <tt>va_list*</tt> value and the type of
3737the argument. It returns a value of the specified argument type and
3738increments the <tt>va_list</tt> to point to the next argument. The
3739actual type of <tt>va_list</tt> is target specific.</p>
3740
3741<h5>Semantics:</h5>
3742
3743<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3744type from the specified <tt>va_list</tt> and causes the
3745<tt>va_list</tt> to point to the next argument. For more information,
3746see the variable argument handling <a href="#int_varargs">Intrinsic
3747Functions</a>.</p>
3748
3749<p>It is legal for this instruction to be called in a function which does not
3750take a variable number of arguments, for example, the <tt>vfprintf</tt>
3751function.</p>
3752
3753<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
3754href="#intrinsics">intrinsic function</a> because it takes a type as an
3755argument.</p>
3756
3757<h5>Example:</h5>
3758
3759<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3760
3761</div>
3762
3763<!-- *********************************************************************** -->
3764<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3765<!-- *********************************************************************** -->
3766
3767<div class="doc_text">
3768
3769<p>LLVM supports the notion of an "intrinsic function". These functions have
3770well known names and semantics and are required to follow certain restrictions.
3771Overall, these intrinsics represent an extension mechanism for the LLVM
3772language that does not require changing all of the transformations in LLVM when
3773adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
3774
3775<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3776prefix is reserved in LLVM for intrinsic names; thus, function names may not
3777begin with this prefix. Intrinsic functions must always be external functions:
3778you cannot define the body of intrinsic functions. Intrinsic functions may
3779only be used in call or invoke instructions: it is illegal to take the address
3780of an intrinsic function. Additionally, because intrinsic functions are part
3781of the LLVM language, it is required if any are added that they be documented
3782here.</p>
3783
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3784<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
3785a family of functions that perform the same operation but on different data
3786types. Because LLVM can represent over 8 million different integer types,
3787overloading is used commonly to allow an intrinsic function to operate on any
3788integer type. One or more of the argument types or the result type can be
3789overloaded to accept any integer type. Argument types may also be defined as
3790exactly matching a previous argument's type or the result type. This allows an
3791intrinsic function which accepts multiple arguments, but needs all of them to
3792be of the same type, to only be overloaded with respect to a single argument or
3793the result.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3794
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3795<p>Overloaded intrinsics will have the names of its overloaded argument types
3796encoded into its function name, each preceded by a period. Only those types
3797which are overloaded result in a name suffix. Arguments whose type is matched
3798against another type do not. For example, the <tt>llvm.ctpop</tt> function can
3799take an integer of any width and returns an integer of exactly the same integer
3800width. This leads to a family of functions such as
3801<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
3802Only one type, the return type, is overloaded, and only one type suffix is
3803required. Because the argument's type is matched against the return type, it
3804does not require its own name suffix.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3805
3806<p>To learn how to add an intrinsic function, please see the
3807<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
3808</p>
3809
3810</div>
3811
3812<!-- ======================================================================= -->
3813<div class="doc_subsection">
3814 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3815</div>
3816
3817<div class="doc_text">
3818
3819<p>Variable argument support is defined in LLVM with the <a
3820 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
3821intrinsic functions. These functions are related to the similarly
3822named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
3823
3824<p>All of these functions operate on arguments that use a
3825target-specific value type "<tt>va_list</tt>". The LLVM assembly
3826language reference manual does not define what this type is, so all
3827transformations should be prepared to handle these functions regardless of
3828the type used.</p>
3829
3830<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
3831instruction and the variable argument handling intrinsic functions are
3832used.</p>
3833
3834<div class="doc_code">
3835<pre>
3836define i32 @test(i32 %X, ...) {
3837 ; Initialize variable argument processing
3838 %ap = alloca i8*
3839 %ap2 = bitcast i8** %ap to i8*
3840 call void @llvm.va_start(i8* %ap2)
3841
3842 ; Read a single integer argument
3843 %tmp = va_arg i8** %ap, i32
3844
3845 ; Demonstrate usage of llvm.va_copy and llvm.va_end
3846 %aq = alloca i8*
3847 %aq2 = bitcast i8** %aq to i8*
3848 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
3849 call void @llvm.va_end(i8* %aq2)
3850
3851 ; Stop processing of arguments.
3852 call void @llvm.va_end(i8* %ap2)
3853 ret i32 %tmp
3854}
3855
3856declare void @llvm.va_start(i8*)
3857declare void @llvm.va_copy(i8*, i8*)
3858declare void @llvm.va_end(i8*)
3859</pre>
3860</div>
3861
3862</div>
3863
3864<!-- _______________________________________________________________________ -->
3865<div class="doc_subsubsection">
3866 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3867</div>
3868
3869
3870<div class="doc_text">
3871<h5>Syntax:</h5>
3872<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
3873<h5>Overview:</h5>
3874<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3875<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3876href="#i_va_arg">va_arg</a></tt>.</p>
3877
3878<h5>Arguments:</h5>
3879
3880<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3881
3882<h5>Semantics:</h5>
3883
3884<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3885macro available in C. In a target-dependent way, it initializes the
3886<tt>va_list</tt> element to which the argument points, so that the next call to
3887<tt>va_arg</tt> will produce the first variable argument passed to the function.
3888Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3889last argument of the function as the compiler can figure that out.</p>
3890
3891</div>
3892
3893<!-- _______________________________________________________________________ -->
3894<div class="doc_subsubsection">
3895 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3896</div>
3897
3898<div class="doc_text">
3899<h5>Syntax:</h5>
3900<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
3901<h5>Overview:</h5>
3902
3903<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
3904which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
3905or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
3906
3907<h5>Arguments:</h5>
3908
3909<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
3910
3911<h5>Semantics:</h5>
3912
3913<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
3914macro available in C. In a target-dependent way, it destroys the
3915<tt>va_list</tt> element to which the argument points. Calls to <a
3916href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
3917<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
3918<tt>llvm.va_end</tt>.</p>
3919
3920</div>
3921
3922<!-- _______________________________________________________________________ -->
3923<div class="doc_subsubsection">
3924 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3925</div>
3926
3927<div class="doc_text">
3928
3929<h5>Syntax:</h5>
3930
3931<pre>
3932 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
3933</pre>
3934
3935<h5>Overview:</h5>
3936
3937<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
3938from the source argument list to the destination argument list.</p>
3939
3940<h5>Arguments:</h5>
3941
3942<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
3943The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
3944
3945
3946<h5>Semantics:</h5>
3947
3948<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
3949macro available in C. In a target-dependent way, it copies the source
3950<tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
3951intrinsic is necessary because the <tt><a href="#int_va_start">
3952llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
3953example, memory allocation.</p>
3954
3955</div>
3956
3957<!-- ======================================================================= -->
3958<div class="doc_subsection">
3959 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3960</div>
3961
3962<div class="doc_text">
3963
3964<p>
3965LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3966Collection</a> requires the implementation and generation of these intrinsics.
3967These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
3968stack</a>, as well as garbage collector implementations that require <a
3969href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
3970Front-ends for type-safe garbage collected languages should generate these
3971intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3972href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3973</p>
3974</div>
3975
3976<!-- _______________________________________________________________________ -->
3977<div class="doc_subsubsection">
3978 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3979</div>
3980
3981<div class="doc_text">
3982
3983<h5>Syntax:</h5>
3984
3985<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]3986 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3987</pre>
3988
3989<h5>Overview:</h5>
3990
3991<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
3992the code generator, and allows some metadata to be associated with it.</p>
3993
3994<h5>Arguments:</h5>
3995
3996<p>The first argument specifies the address of a stack object that contains the
3997root pointer. The second pointer (which must be either a constant or a global
3998value address) contains the meta-data to be associated with the root.</p>
3999
4000<h5>Semantics:</h5>
4001
4002<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
4003location. At compile-time, the code generator generates information to allow
4004the runtime to find the pointer at GC safe points.
4005</p>
4006
4007</div>
4008
4009
4010<!-- _______________________________________________________________________ -->
4011<div class="doc_subsubsection">
4012 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
4013</div>
4014
4015<div class="doc_text">
4016
4017<h5>Syntax:</h5>
4018
4019<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4020 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4021</pre>
4022
4023<h5>Overview:</h5>
4024
4025<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
4026locations, allowing garbage collector implementations that require read
4027barriers.</p>
4028
4029<h5>Arguments:</h5>
4030
4031<p>The second argument is the address to read from, which should be an address
4032allocated from the garbage collector. The first object is a pointer to the
4033start of the referenced object, if needed by the language runtime (otherwise
4034null).</p>
4035
4036<h5>Semantics:</h5>
4037
4038<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
4039instruction, but may be replaced with substantially more complex code by the
4040garbage collector runtime, as needed.</p>
4041
4042</div>
4043
4044
4045<!-- _______________________________________________________________________ -->
4046<div class="doc_subsubsection">
4047 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
4048</div>
4049
4050<div class="doc_text">
4051
4052<h5>Syntax:</h5>
4053
4054<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4055 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4056</pre>
4057
4058<h5>Overview:</h5>
4059
4060<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
4061locations, allowing garbage collector implementations that require write
4062barriers (such as generational or reference counting collectors).</p>
4063
4064<h5>Arguments:</h5>
4065
4066<p>The first argument is the reference to store, the second is the start of the
4067object to store it to, and the third is the address of the field of Obj to
4068store to. If the runtime does not require a pointer to the object, Obj may be
4069null.</p>
4070
4071<h5>Semantics:</h5>
4072
4073<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
4074instruction, but may be replaced with substantially more complex code by the
4075garbage collector runtime, as needed.</p>
4076
4077</div>
4078
4079
4080
4081<!-- ======================================================================= -->
4082<div class="doc_subsection">
4083 <a name="int_codegen">Code Generator Intrinsics</a>
4084</div>
4085
4086<div class="doc_text">
4087<p>
4088These intrinsics are provided by LLVM to expose special features that may only
4089be implemented with code generator support.
4090</p>
4091
4092</div>
4093
4094<!-- _______________________________________________________________________ -->
4095<div class="doc_subsubsection">
4096 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
4097</div>
4098
4099<div class="doc_text">
4100
4101<h5>Syntax:</h5>
4102<pre>
4103 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
4104</pre>
4105
4106<h5>Overview:</h5>
4107
4108<p>
4109The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
4110target-specific value indicating the return address of the current function
4111or one of its callers.
4112</p>
4113
4114<h5>Arguments:</h5>
4115
4116<p>
4117The argument to this intrinsic indicates which function to return the address
4118for. Zero indicates the calling function, one indicates its caller, etc. The
4119argument is <b>required</b> to be a constant integer value.
4120</p>
4121
4122<h5>Semantics:</h5>
4123
4124<p>
4125The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
4126the return address of the specified call frame, or zero if it cannot be
4127identified. The value returned by this intrinsic is likely to be incorrect or 0
4128for arguments other than zero, so it should only be used for debugging purposes.
4129</p>
4130
4131<p>
4132Note that calling this intrinsic does not prevent function inlining or other
4133aggressive transformations, so the value returned may not be that of the obvious
4134source-language caller.
4135</p>
4136</div>
4137
4138
4139<!-- _______________________________________________________________________ -->
4140<div class="doc_subsubsection">
4141 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
4142</div>
4143
4144<div class="doc_text">
4145
4146<h5>Syntax:</h5>
4147<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4148 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4149</pre>
4150
4151<h5>Overview:</h5>
4152
4153<p>
4154The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
4155target-specific frame pointer value for the specified stack frame.
4156</p>
4157
4158<h5>Arguments:</h5>
4159
4160<p>
4161The argument to this intrinsic indicates which function to return the frame
4162pointer for. Zero indicates the calling function, one indicates its caller,
4163etc. The argument is <b>required</b> to be a constant integer value.
4164</p>
4165
4166<h5>Semantics:</h5>
4167
4168<p>
4169The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
4170the frame address of the specified call frame, or zero if it cannot be
4171identified. The value returned by this intrinsic is likely to be incorrect or 0
4172for arguments other than zero, so it should only be used for debugging purposes.
4173</p>
4174
4175<p>
4176Note that calling this intrinsic does not prevent function inlining or other
4177aggressive transformations, so the value returned may not be that of the obvious
4178source-language caller.
4179</p>
4180</div>
4181
4182<!-- _______________________________________________________________________ -->
4183<div class="doc_subsubsection">
4184 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
4185</div>
4186
4187<div class="doc_text">
4188
4189<h5>Syntax:</h5>
4190<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4191 declare i8 *@llvm.stacksave()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4192</pre>
4193
4194<h5>Overview:</h5>
4195
4196<p>
4197The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
4198the function stack, for use with <a href="#int_stackrestore">
4199<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4200features like scoped automatic variable sized arrays in C99.
4201</p>
4202
4203<h5>Semantics:</h5>
4204
4205<p>
4206This intrinsic returns a opaque pointer value that can be passed to <a
4207href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
4208<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4209<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4210state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4211practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4212that were allocated after the <tt>llvm.stacksave</tt> was executed.
4213</p>
4214
4215</div>
4216
4217<!-- _______________________________________________________________________ -->
4218<div class="doc_subsubsection">
4219 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
4220</div>
4221
4222<div class="doc_text">
4223
4224<h5>Syntax:</h5>
4225<pre>
4226 declare void @llvm.stackrestore(i8 * %ptr)
4227</pre>
4228
4229<h5>Overview:</h5>
4230
4231<p>
4232The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4233the function stack to the state it was in when the corresponding <a
4234href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
4235useful for implementing language features like scoped automatic variable sized
4236arrays in C99.
4237</p>
4238
4239<h5>Semantics:</h5>
4240
4241<p>
4242See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
4243</p>
4244
4245</div>
4246
4247
4248<!-- _______________________________________________________________________ -->
4249<div class="doc_subsubsection">
4250 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
4251</div>
4252
4253<div class="doc_text">
4254
4255<h5>Syntax:</h5>
4256<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4257 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]4258</pre>
4259
4260<h5>Overview:</h5>
4261
4262
4263<p>
4264The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
4265a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4266no
4267effect on the behavior of the program but can change its performance
4268characteristics.
4269</p>
4270
4271<h5>Arguments:</h5>
4272
4273<p>
4274<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4275determining if the fetch should be for a read (0) or write (1), and
4276<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
4277locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
4278<tt>locality</tt> arguments must be constant integers.
4279</p>
4280
4281<h5>Semantics:</h5>
4282
4283<p>
4284This intrinsic does not modify the behavior of the program. In particular,
4285prefetches cannot trap and do not produce a value. On targets that support this
4286intrinsic, the prefetch can provide hints to the processor cache for better
4287performance.
4288</p>
4289
4290</div>
4291
4292<!-- _______________________________________________________________________ -->
4293<div class="doc_subsubsection">
4294 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4295</div>
4296
4297<div class="doc_text">
4298
4299<h5>Syntax:</h5>
4300<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4301 declare void @llvm.pcmarker(i32 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4302</pre>
4303
4304<h5>Overview:</h5>
4305
4306
4307<p>
4308The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4309(PC) in a region of
4310code to simulators and other tools. The method is target specific, but it is
4311expected that the marker will use exported symbols to transmit the PC of the marker.
4312The marker makes no guarantees that it will remain with any specific instruction
4313after optimizations. It is possible that the presence of a marker will inhibit
4314optimizations. The intended use is to be inserted after optimizations to allow
4315correlations of simulation runs.
4316</p>
4317
4318<h5>Arguments:</h5>
4319
4320<p>
4321<tt>id</tt> is a numerical id identifying the marker.
4322</p>
4323
4324<h5>Semantics:</h5>
4325
4326<p>
4327This intrinsic does not modify the behavior of the program. Backends that do not
4328support this intrinisic may ignore it.
4329</p>
4330
4331</div>
4332
4333<!-- _______________________________________________________________________ -->
4334<div class="doc_subsubsection">
4335 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4336</div>
4337
4338<div class="doc_text">
4339
4340<h5>Syntax:</h5>
4341<pre>
4342 declare i64 @llvm.readcyclecounter( )
4343</pre>
4344
4345<h5>Overview:</h5>
4346
4347
4348<p>
4349The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4350counter register (or similar low latency, high accuracy clocks) on those targets
4351that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4352As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4353should only be used for small timings.
4354</p>
4355
4356<h5>Semantics:</h5>
4357
4358<p>
4359When directly supported, reading the cycle counter should not modify any memory.
4360Implementations are allowed to either return a application specific value or a
4361system wide value. On backends without support, this is lowered to a constant 0.
4362</p>
4363
4364</div>
4365
4366<!-- ======================================================================= -->
4367<div class="doc_subsection">
4368 <a name="int_libc">Standard C Library Intrinsics</a>
4369</div>
4370
4371<div class="doc_text">
4372<p>
4373LLVM provides intrinsics for a few important standard C library functions.
4374These intrinsics allow source-language front-ends to pass information about the
4375alignment of the pointer arguments to the code generator, providing opportunity
4376for more efficient code generation.
4377</p>
4378
4379</div>
4380
4381<!-- _______________________________________________________________________ -->
4382<div class="doc_subsubsection">
4383 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4384</div>
4385
4386<div class="doc_text">
4387
4388<h5>Syntax:</h5>
4389<pre>
4390 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4391 i32 &lt;len&gt;, i32 &lt;align&gt;)
4392 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4393 i64 &lt;len&gt;, i32 &lt;align&gt;)
4394</pre>
4395
4396<h5>Overview:</h5>
4397
4398<p>
4399The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4400location to the destination location.
4401</p>
4402
4403<p>
4404Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4405intrinsics do not return a value, and takes an extra alignment argument.
4406</p>
4407
4408<h5>Arguments:</h5>
4409
4410<p>
4411The first argument is a pointer to the destination, the second is a pointer to
4412the source. The third argument is an integer argument
4413specifying the number of bytes to copy, and the fourth argument is the alignment
4414of the source and destination locations.
4415</p>
4416
4417<p>
4418If the call to this intrinisic has an alignment value that is not 0 or 1, then
4419the caller guarantees that both the source and destination pointers are aligned
4420to that boundary.
4421</p>
4422
4423<h5>Semantics:</h5>
4424
4425<p>
4426The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4427location to the destination location, which are not allowed to overlap. It
4428copies "len" bytes of memory over. If the argument is known to be aligned to
4429some boundary, this can be specified as the fourth argument, otherwise it should
4430be set to 0 or 1.
4431</p>
4432</div>
4433
4434
4435<!-- _______________________________________________________________________ -->
4436<div class="doc_subsubsection">
4437 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4438</div>
4439
4440<div class="doc_text">
4441
4442<h5>Syntax:</h5>
4443<pre>
4444 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4445 i32 &lt;len&gt;, i32 &lt;align&gt;)
4446 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4447 i64 &lt;len&gt;, i32 &lt;align&gt;)
4448</pre>
4449
4450<h5>Overview:</h5>
4451
4452<p>
4453The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4454location to the destination location. It is similar to the
4455'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
4456</p>
4457
4458<p>
4459Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4460intrinsics do not return a value, and takes an extra alignment argument.
4461</p>
4462
4463<h5>Arguments:</h5>
4464
4465<p>
4466The first argument is a pointer to the destination, the second is a pointer to
4467the source. The third argument is an integer argument
4468specifying the number of bytes to copy, and the fourth argument is the alignment
4469of the source and destination locations.
4470</p>
4471
4472<p>
4473If the call to this intrinisic has an alignment value that is not 0 or 1, then
4474the caller guarantees that the source and destination pointers are aligned to
4475that boundary.
4476</p>
4477
4478<h5>Semantics:</h5>
4479
4480<p>
4481The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
4482location to the destination location, which may overlap. It
4483copies "len" bytes of memory over. If the argument is known to be aligned to
4484some boundary, this can be specified as the fourth argument, otherwise it should
4485be set to 0 or 1.
4486</p>
4487</div>
4488
4489
4490<!-- _______________________________________________________________________ -->
4491<div class="doc_subsubsection">
4492 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
4493</div>
4494
4495<div class="doc_text">
4496
4497<h5>Syntax:</h5>
4498<pre>
4499 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4500 i32 &lt;len&gt;, i32 &lt;align&gt;)
4501 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4502 i64 &lt;len&gt;, i32 &lt;align&gt;)
4503</pre>
4504
4505<h5>Overview:</h5>
4506
4507<p>
4508The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
4509byte value.
4510</p>
4511
4512<p>
4513Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4514does not return a value, and takes an extra alignment argument.
4515</p>
4516
4517<h5>Arguments:</h5>
4518
4519<p>
4520The first argument is a pointer to the destination to fill, the second is the
4521byte value to fill it with, the third argument is an integer
4522argument specifying the number of bytes to fill, and the fourth argument is the
4523known alignment of destination location.
4524</p>
4525
4526<p>
4527If the call to this intrinisic has an alignment value that is not 0 or 1, then
4528the caller guarantees that the destination pointer is aligned to that boundary.
4529</p>
4530
4531<h5>Semantics:</h5>
4532
4533<p>
4534The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4535the
4536destination location. If the argument is known to be aligned to some boundary,
4537this can be specified as the fourth argument, otherwise it should be set to 0 or
45381.
4539</p>
4540</div>
4541
4542
4543<!-- _______________________________________________________________________ -->
4544<div class="doc_subsubsection">
4545 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
4546</div>
4547
4548<div class="doc_text">
4549
4550<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4551<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]4552floating point or vector of floating point type. Not all targets support all
4553types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4554<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4555 declare float @llvm.sqrt.f32(float %Val)
4556 declare double @llvm.sqrt.f64(double %Val)
4557 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
4558 declare fp128 @llvm.sqrt.f128(fp128 %Val)
4559 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4560</pre>
4561
4562<h5>Overview:</h5>
4563
4564<p>
4565The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4566returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4567<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4568negative numbers (which allows for better optimization).
4569</p>
4570
4571<h5>Arguments:</h5>
4572
4573<p>
4574The argument and return value are floating point numbers of the same type.
4575</p>
4576
4577<h5>Semantics:</h5>
4578
4579<p>
4580This function returns the sqrt of the specified operand if it is a nonnegative
4581floating point number.
4582</p>
4583</div>
4584
4585<!-- _______________________________________________________________________ -->
4586<div class="doc_subsubsection">
4587 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4588</div>
4589
4590<div class="doc_text">
4591
4592<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4593<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]4594floating point or vector of floating point type. Not all targets support all
4595types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4596<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4597 declare float @llvm.powi.f32(float %Val, i32 %power)
4598 declare double @llvm.powi.f64(double %Val, i32 %power)
4599 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
4600 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
4601 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4602</pre>
4603
4604<h5>Overview:</h5>
4605
4606<p>
4607The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4608specified (positive or negative) power. The order of evaluation of
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4609multiplications is not defined. When a vector of floating point type is
4610used, the second argument remains a scalar integer value.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4611</p>
4612
4613<h5>Arguments:</h5>
4614
4615<p>
4616The second argument is an integer power, and the first is a value to raise to
4617that power.
4618</p>
4619
4620<h5>Semantics:</h5>
4621
4622<p>
4623This function returns the first value raised to the second power with an
4624unspecified sequence of rounding operations.</p>
4625</div>
4626
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4627<!-- _______________________________________________________________________ -->
4628<div class="doc_subsubsection">
4629 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
4630</div>
4631
4632<div class="doc_text">
4633
4634<h5>Syntax:</h5>
4635<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
4636floating point or vector of floating point type. Not all targets support all
4637types however.
4638<pre>
4639 declare float @llvm.sin.f32(float %Val)
4640 declare double @llvm.sin.f64(double %Val)
4641 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
4642 declare fp128 @llvm.sin.f128(fp128 %Val)
4643 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
4644</pre>
4645
4646<h5>Overview:</h5>
4647
4648<p>
4649The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
4650</p>
4651
4652<h5>Arguments:</h5>
4653
4654<p>
4655The argument and return value are floating point numbers of the same type.
4656</p>
4657
4658<h5>Semantics:</h5>
4659
4660<p>
4661This function returns the sine of the specified operand, returning the
4662same values as the libm <tt>sin</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4663conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4664</div>
4665
4666<!-- _______________________________________________________________________ -->
4667<div class="doc_subsubsection">
4668 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
4669</div>
4670
4671<div class="doc_text">
4672
4673<h5>Syntax:</h5>
4674<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
4675floating point or vector of floating point type. Not all targets support all
4676types however.
4677<pre>
4678 declare float @llvm.cos.f32(float %Val)
4679 declare double @llvm.cos.f64(double %Val)
4680 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
4681 declare fp128 @llvm.cos.f128(fp128 %Val)
4682 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
4683</pre>
4684
4685<h5>Overview:</h5>
4686
4687<p>
4688The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
4689</p>
4690
4691<h5>Arguments:</h5>
4692
4693<p>
4694The argument and return value are floating point numbers of the same type.
4695</p>
4696
4697<h5>Semantics:</h5>
4698
4699<p>
4700This function returns the cosine of the specified operand, returning the
4701same values as the libm <tt>cos</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4702conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4703</div>
4704
4705<!-- _______________________________________________________________________ -->
4706<div class="doc_subsubsection">
4707 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
4708</div>
4709
4710<div class="doc_text">
4711
4712<h5>Syntax:</h5>
4713<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
4714floating point or vector of floating point type. Not all targets support all
4715types however.
4716<pre>
4717 declare float @llvm.pow.f32(float %Val, float %Power)
4718 declare double @llvm.pow.f64(double %Val, double %Power)
4719 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
4720 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
4721 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
4722</pre>
4723
4724<h5>Overview:</h5>
4725
4726<p>
4727The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
4728specified (positive or negative) power.
4729</p>
4730
4731<h5>Arguments:</h5>
4732
4733<p>
4734The second argument is a floating point power, and the first is a value to
4735raise to that power.
4736</p>
4737
4738<h5>Semantics:</h5>
4739
4740<p>
4741This function returns the first value raised to the second power,
4742returning the
4743same values as the libm <tt>pow</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4744conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4745</div>
4746
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4747
4748<!-- ======================================================================= -->
4749<div class="doc_subsection">
4750 <a name="int_manip">Bit Manipulation Intrinsics</a>
4751</div>
4752
4753<div class="doc_text">
4754<p>
4755LLVM provides intrinsics for a few important bit manipulation operations.
4756These allow efficient code generation for some algorithms.
4757</p>
4758
4759</div>
4760
4761<!-- _______________________________________________________________________ -->
4762<div class="doc_subsubsection">
4763 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4764</div>
4765
4766<div class="doc_text">
4767
4768<h5>Syntax:</h5>
4769<p>This is an overloaded intrinsic function. You can use bswap on any integer
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4770type that is an even number of bytes (i.e. BitWidth % 16 == 0).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4771<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4772 declare i16 @llvm.bswap.i16(i16 &lt;id&gt;)
4773 declare i32 @llvm.bswap.i32(i32 &lt;id&gt;)
4774 declare i64 @llvm.bswap.i64(i64 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4775</pre>
4776
4777<h5>Overview:</h5>
4778
4779<p>
4780The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
4781values with an even number of bytes (positive multiple of 16 bits). These are
4782useful for performing operations on data that is not in the target's native
4783byte order.
4784</p>
4785
4786<h5>Semantics:</h5>
4787
4788<p>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4789The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4790and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4791intrinsic returns an i32 value that has the four bytes of the input i32
4792swapped, 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]4793i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
4794<tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4795additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
4796</p>
4797
4798</div>
4799
4800<!-- _______________________________________________________________________ -->
4801<div class="doc_subsubsection">
4802 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
4803</div>
4804
4805<div class="doc_text">
4806
4807<h5>Syntax:</h5>
4808<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4809width. Not all targets support all bit widths however.
4810<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4811 declare i8 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4812 declare i16 @llvm.ctpop.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4813 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4814 declare i64 @llvm.ctpop.i64(i64 &lt;src&gt;)
4815 declare i256 @llvm.ctpop.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4816</pre>
4817
4818<h5>Overview:</h5>
4819
4820<p>
4821The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4822value.
4823</p>
4824
4825<h5>Arguments:</h5>
4826
4827<p>
4828The only argument is the value to be counted. The argument may be of any
4829integer type. The return type must match the argument type.
4830</p>
4831
4832<h5>Semantics:</h5>
4833
4834<p>
4835The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4836</p>
4837</div>
4838
4839<!-- _______________________________________________________________________ -->
4840<div class="doc_subsubsection">
4841 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
4842</div>
4843
4844<div class="doc_text">
4845
4846<h5>Syntax:</h5>
4847<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4848integer bit width. Not all targets support all bit widths however.
4849<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4850 declare i8 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4851 declare i16 @llvm.ctlz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4852 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4853 declare i64 @llvm.ctlz.i64(i64 &lt;src&gt;)
4854 declare i256 @llvm.ctlz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4855</pre>
4856
4857<h5>Overview:</h5>
4858
4859<p>
4860The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4861leading zeros in a variable.
4862</p>
4863
4864<h5>Arguments:</h5>
4865
4866<p>
4867The only argument is the value to be counted. The argument may be of any
4868integer type. The return type must match the argument type.
4869</p>
4870
4871<h5>Semantics:</h5>
4872
4873<p>
4874The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4875in a variable. If the src == 0 then the result is the size in bits of the type
4876of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
4877</p>
4878</div>
4879
4880
4881
4882<!-- _______________________________________________________________________ -->
4883<div class="doc_subsubsection">
4884 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
4885</div>
4886
4887<div class="doc_text">
4888
4889<h5>Syntax:</h5>
4890<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4891integer bit width. Not all targets support all bit widths however.
4892<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4893 declare i8 @llvm.cttz.i8 (i8 &lt;src&gt;)
4894 declare i16 @llvm.cttz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4895 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4896 declare i64 @llvm.cttz.i64(i64 &lt;src&gt;)
4897 declare i256 @llvm.cttz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4898</pre>
4899
4900<h5>Overview:</h5>
4901
4902<p>
4903The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4904trailing zeros.
4905</p>
4906
4907<h5>Arguments:</h5>
4908
4909<p>
4910The only argument is the value to be counted. The argument may be of any
4911integer type. The return type must match the argument type.
4912</p>
4913
4914<h5>Semantics:</h5>
4915
4916<p>
4917The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4918in a variable. If the src == 0 then the result is the size in bits of the type
4919of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4920</p>
4921</div>
4922
4923<!-- _______________________________________________________________________ -->
4924<div class="doc_subsubsection">
4925 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
4926</div>
4927
4928<div class="doc_text">
4929
4930<h5>Syntax:</h5>
4931<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
4932on any integer bit width.
4933<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4934 declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
4935 declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4936</pre>
4937
4938<h5>Overview:</h5>
4939<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
4940range of bits from an integer value and returns them in the same bit width as
4941the original value.</p>
4942
4943<h5>Arguments:</h5>
4944<p>The first argument, <tt>%val</tt> and the result may be integer types of
4945any bit width but they must have the same bit width. The second and third
4946arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
4947
4948<h5>Semantics:</h5>
4949<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
4950of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
4951<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
4952operates in forward mode.</p>
4953<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
4954right by <tt>%loBit</tt> bits and then ANDing it with a mask with
4955only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
4956<ol>
4957 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
4958 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
4959 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
4960 to determine the number of bits to retain.</li>
4961 <li>A mask of the retained bits is created by shifting a -1 value.</li>
4962 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
4963</ol>
4964<p>In reverse mode, a similar computation is made except that the bits are
4965returned in the reverse order. So, for example, if <tt>X</tt> has the value
4966<tt>i16 0x0ACF (101011001111)</tt> and we apply
4967<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
4968<tt>i16 0x0026 (000000100110)</tt>.</p>
4969</div>
4970
4971<div class="doc_subsubsection">
4972 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
4973</div>
4974
4975<div class="doc_text">
4976
4977<h5>Syntax:</h5>
4978<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
4979on any integer bit width.
4980<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4981 declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
4982 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]4983</pre>
4984
4985<h5>Overview:</h5>
4986<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
4987of bits in an integer value with another integer value. It returns the integer
4988with the replaced bits.</p>
4989
4990<h5>Arguments:</h5>
4991<p>The first argument, <tt>%val</tt> and the result may be integer types of
4992any bit width but they must have the same bit width. <tt>%val</tt> is the value
4993whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
4994integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
4995type since they specify only a bit index.</p>
4996
4997<h5>Semantics:</h5>
4998<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
4999of operation: forwards and reverse. If <tt>%lo</tt> is greater than
5000<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
5001operates in forward mode.</p>
5002<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
5003truncating it down to the size of the replacement area or zero extending it
5004up to that size.</p>
5005<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
5006are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
5007in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
5008to the <tt>%hi</tt>th bit.
5009<p>In reverse mode, a similar computation is made except that the bits are
5010reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
5011<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
5012<h5>Examples:</h5>
5013<pre>
5014 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
5015 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0xFF0F
5016 llvm.part.set(0xFFFF, 1, 7, 4) -&gt; 0xFF8F
5017 llvm.part.set(0xFFFF, F, 8, 3) -&gt; 0xFFE7
5018 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
5019</pre>
5020</div>
5021
5022<!-- ======================================================================= -->
5023<div class="doc_subsection">
5024 <a name="int_debugger">Debugger Intrinsics</a>
5025</div>
5026
5027<div class="doc_text">
5028<p>
5029The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
5030are described in the <a
5031href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
5032Debugging</a> document.
5033</p>
5034</div>
5035
5036
5037<!-- ======================================================================= -->
5038<div class="doc_subsection">
5039 <a name="int_eh">Exception Handling Intrinsics</a>
5040</div>
5041
5042<div class="doc_text">
5043<p> The LLVM exception handling intrinsics (which all start with
5044<tt>llvm.eh.</tt> prefix), are described in the <a
5045href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
5046Handling</a> document. </p>
5047</div>
5048
5049<!-- ======================================================================= -->
5050<div class="doc_subsection">
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5051 <a name="int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5052</div>
5053
5054<div class="doc_text">
5055<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5056 This intrinsic makes it possible to excise one parameter, marked with
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5057 the <tt>nest</tt> attribute, from a function. The result is a callable
5058 function pointer lacking the nest parameter - the caller does not need
5059 to provide a value for it. Instead, the value to use is stored in
5060 advance in a "trampoline", a block of memory usually allocated
5061 on the stack, which also contains code to splice the nest value into the
5062 argument list. This is used to implement the GCC nested function address
5063 extension.
5064</p>
5065<p>
5066 For example, if the function is
5067 <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]5068 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]5069<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5070 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
5071 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
5072 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
5073 %fp = bitcast i8* %p to i32 (i32, i32)*
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5074</pre>
Bill Wendlinge262b4c2007-09-22 09:23:55 +0000[diff] [blame]5075 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
5076 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5077</div>
5078
5079<!-- _______________________________________________________________________ -->
5080<div class="doc_subsubsection">
5081 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
5082</div>
5083<div class="doc_text">
5084<h5>Syntax:</h5>
5085<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5086declare 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]5087</pre>
5088<h5>Overview:</h5>
5089<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5090 This fills the memory pointed to by <tt>tramp</tt> with code
5091 and returns a function pointer suitable for executing it.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5092</p>
5093<h5>Arguments:</h5>
5094<p>
5095 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
5096 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
5097 and sufficiently aligned block of memory; this memory is written to by the
Duncan Sands35012212007-08-22 23:39:54 +0000[diff] [blame]5098 intrinsic. Note that the size and the alignment are target-specific - LLVM
5099 currently provides no portable way of determining them, so a front-end that
5100 generates this intrinsic needs to have some target-specific knowledge.
5101 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]5102</p>
5103<h5>Semantics:</h5>
5104<p>
5105 The block of memory pointed to by <tt>tramp</tt> is filled with target
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5106 dependent code, turning it into a function. A pointer to this function is
5107 returned, but needs to be bitcast to an
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5108 <a href="#int_trampoline">appropriate function pointer type</a>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5109 before being called. The new function's signature is the same as that of
5110 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
5111 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
5112 of pointer type. Calling the new function is equivalent to calling
5113 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
5114 missing <tt>nest</tt> argument. If, after calling
5115 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
5116 modified, then the effect of any later call to the returned function pointer is
5117 undefined.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5118</p>
5119</div>
5120
5121<!-- ======================================================================= -->
5122<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5123 <a name="int_general">General Intrinsics</a>
5124</div>
5125
5126<div class="doc_text">
5127<p> This class of intrinsics is designed to be generic and has
5128no specific purpose. </p>
5129</div>
5130
5131<!-- _______________________________________________________________________ -->
5132<div class="doc_subsubsection">
5133 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
5134</div>
5135
5136<div class="doc_text">
5137
5138<h5>Syntax:</h5>
5139<pre>
5140 declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5141</pre>
5142
5143<h5>Overview:</h5>
5144
5145<p>
5146The '<tt>llvm.var.annotation</tt>' intrinsic
5147</p>
5148
5149<h5>Arguments:</h5>
5150
5151<p>
5152The first argument is a pointer to a value, the second is a pointer to a
5153global string, the third is a pointer to a global string which is the source
5154file name, and the last argument is the line number.
5155</p>
5156
5157<h5>Semantics:</h5>
5158
5159<p>
5160This intrinsic allows annotation of local variables with arbitrary strings.
5161This can be useful for special purpose optimizations that want to look for these
5162 annotations. These have no other defined use, they are ignored by code
5163 generation and optimization.
5164</div>
5165
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5166<!-- _______________________________________________________________________ -->
5167<div class="doc_subsubsection">
Tanya Lattnerc9869b12007-09-21 23:57:59 +0000[diff] [blame]5168 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5169</div>
5170
5171<div class="doc_text">
5172
5173<h5>Syntax:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5174<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
5175any integer bit width.
5176</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5177<pre>
Tanya Lattner09161fe2007-09-22 00:03:01 +0000[diff] [blame]5178 declare i8 @llvm.annotation.i8(i8 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5179 declare i16 @llvm.annotation.i16(i16 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5180 declare i32 @llvm.annotation.i32(i32 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5181 declare i64 @llvm.annotation.i64(i64 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5182 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]5183</pre>
5184
5185<h5>Overview:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5186
5187<p>
5188The '<tt>llvm.annotation</tt>' intrinsic.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5189</p>
5190
5191<h5>Arguments:</h5>
5192
5193<p>
5194The first argument is an integer value (result of some expression),
5195the second is a pointer to a global string, the third is a pointer to a global
5196string which is the source file name, and the last argument is the line number.
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5197It returns the value of the first argument.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5198</p>
5199
5200<h5>Semantics:</h5>
5201
5202<p>
5203This intrinsic allows annotations to be put on arbitrary expressions
5204with arbitrary strings. This can be useful for special purpose optimizations
5205that want to look for these annotations. These have no other defined use, they
5206are ignored by code generation and optimization.
5207</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5208
5209<!-- *********************************************************************** -->
5210<hr>
5211<address>
5212 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
5213 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
5214 <a href="http://validator.w3.org/check/referer"><img
5215 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
5216
5217 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
5218 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
5219 Last modified: $Date$
5220</address>
5221</body>
5222</html>