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5 <title>LLVM Assembly Language Reference Manual</title>
6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
12
13<body>
14
15<div class="doc_title"> LLVM Language Reference Manual </div>
16<ol>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
23 <li><a href="#linkage">Linkage Types</a></li>
24 <li><a href="#callingconv">Calling Conventions</a></li>
25 <li><a href="#globalvars">Global Variables</a></li>
26 <li><a href="#functionstructure">Functions</a></li>
27 <li><a href="#aliasstructure">Aliases</a>
28 <li><a href="#paramattrs">Parameter Attributes</a></li>
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame^]29 <li><a href="#gc">Garbage Collector Names</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]30 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
31 <li><a href="#datalayout">Data Layout</a></li>
32 </ol>
33 </li>
34 <li><a href="#typesystem">Type System</a>
35 <ol>
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
671<p>LLVM allows an explicit section to be specified for globals. If the target
672supports it, it will emit globals to the section specified.</p>
673
674<p>An explicit alignment may be specified for a global. If not present, or if
675the alignment is set to zero, the alignment of the global is set by the target
676to whatever it feels convenient. If an explicit alignment is specified, the
677global is forced to have at least that much alignment. All alignments must be
678a power of 2.</p>
679
680<p>For example, the following defines a global with an initializer, section,
681 and alignment:</p>
682
683<div class="doc_code">
684<pre>
685@G = constant float 1.0, section "foo", align 4
686</pre>
687</div>
688
689</div>
690
691
692<!-- ======================================================================= -->
693<div class="doc_subsection">
694 <a name="functionstructure">Functions</a>
695</div>
696
697<div class="doc_text">
698
699<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
700an optional <a href="#linkage">linkage type</a>, an optional
701<a href="#visibility">visibility style</a>, an optional
702<a href="#callingconv">calling convention</a>, a return type, an optional
703<a href="#paramattrs">parameter attribute</a> for the return type, a function
704name, a (possibly empty) argument list (each with optional
705<a href="#paramattrs">parameter attributes</a>), an optional section, an
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame^]706optional alignment, an optional <a href="gc">garbage collector name</a>, an
707opening curly brace, a list of basic blocks, and a closing curly brace.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]708
709LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
710optional <a href="#linkage">linkage type</a>, an optional
711<a href="#visibility">visibility style</a>, an optional
712<a href="#callingconv">calling convention</a>, a return type, an optional
713<a href="#paramattrs">parameter attribute</a> for the return type, a function
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame^]714name, a possibly empty list of arguments, an optional alignment, and an optional
715<a href="gc">garbage collector name</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]716
717<p>A function definition contains a list of basic blocks, forming the CFG for
718the function. Each basic block may optionally start with a label (giving the
719basic block a symbol table entry), contains a list of instructions, and ends
720with a <a href="#terminators">terminator</a> instruction (such as a branch or
721function return).</p>
722
723<p>The first basic block in a function is special in two ways: it is immediately
724executed on entrance to the function, and it is not allowed to have predecessor
725basic blocks (i.e. there can not be any branches to the entry block of a
726function). Because the block can have no predecessors, it also cannot have any
727<a href="#i_phi">PHI nodes</a>.</p>
728
729<p>LLVM allows an explicit section to be specified for functions. If the target
730supports it, it will emit functions to the section specified.</p>
731
732<p>An explicit alignment may be specified for a function. If not present, or if
733the alignment is set to zero, the alignment of the function is set by the target
734to whatever it feels convenient. If an explicit alignment is specified, the
735function is forced to have at least that much alignment. All alignments must be
736a power of 2.</p>
737
738</div>
739
740
741<!-- ======================================================================= -->
742<div class="doc_subsection">
743 <a name="aliasstructure">Aliases</a>
744</div>
745<div class="doc_text">
746 <p>Aliases act as "second name" for the aliasee value (which can be either
747 function or global variable or bitcast of global value). Aliases may have an
748 optional <a href="#linkage">linkage type</a>, and an
749 optional <a href="#visibility">visibility style</a>.</p>
750
751 <h5>Syntax:</h5>
752
753<div class="doc_code">
754<pre>
755@&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
756</pre>
757</div>
758
759</div>
760
761
762
763<!-- ======================================================================= -->
764<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
765<div class="doc_text">
766 <p>The return type and each parameter of a function type may have a set of
767 <i>parameter attributes</i> associated with them. Parameter attributes are
768 used to communicate additional information about the result or parameters of
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]769 a function. Parameter attributes are considered to be part of the function,
770 not of the function type, so functions with different parameter attributes
771 can have the same function type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]772
773 <p>Parameter attributes are simple keywords that follow the type specified. If
774 multiple parameter attributes are needed, they are space separated. For
775 example:</p>
776
777<div class="doc_code">
778<pre>
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]779declare i32 @printf(i8* noalias , ...) nounwind
780declare i32 @atoi(i8*) nounwind readonly
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]781</pre>
782</div>
783
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]784 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
785 <tt>readonly</tt>) come immediately after the argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]786
787 <p>Currently, only the following parameter attributes are defined:</p>
788 <dl>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]789 <dt><tt>zeroext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]790 <dd>This indicates that the parameter should be zero extended just before
791 a call to this function.</dd>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]792 <dt><tt>signext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]793 <dd>This indicates that the parameter should be sign extended just before
794 a call to this function.</dd>
795 <dt><tt>inreg</tt></dt>
796 <dd>This indicates that the parameter should be placed in register (if
797 possible) during assembling function call. Support for this attribute is
798 target-specific</dd>
799 <dt><tt>sret</tt></dt>
800 <dd>This indicates that the parameter specifies the address of a structure
801 that is the return value of the function in the source program.</dd>
802 <dt><tt>noalias</tt></dt>
803 <dd>This indicates that the parameter not alias any other object or any
804 other "noalias" objects during the function call.
805 <dt><tt>noreturn</tt></dt>
806 <dd>This function attribute indicates that the function never returns. This
807 indicates to LLVM that every call to this function should be treated as if
808 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
809 <dt><tt>nounwind</tt></dt>
810 <dd>This function attribute indicates that the function type does not use
811 the unwind instruction and does not allow stack unwinding to propagate
812 through it.</dd>
Duncan Sands4ee46812007-07-27 19:57:41 +0000[diff] [blame]813 <dt><tt>nest</tt></dt>
814 <dd>This indicates that the parameter can be excised using the
815 <a href="#int_trampoline">trampoline intrinsics</a>.</dd>
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]816 <dt><tt>readonly</tt></dt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]817 <dd>This function attribute indicates that the function has no side-effects
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]818 except for producing a return value or throwing an exception. The value
819 returned must only depend on the function arguments and/or global variables.
820 It may use values obtained by dereferencing pointers.</dd>
821 <dt><tt>readnone</tt></dt>
822 <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]823 function, but in addition it is not allowed to dereference any pointer arguments
824 or global variables.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]825 </dl>
826
827</div>
828
829<!-- ======================================================================= -->
830<div class="doc_subsection">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame^]831 <a name="gc">Garbage Collector Names</a>
832</div>
833
834<div class="doc_text">
835<p>Each function may specify a garbage collector name, which is simply a
836string.</p>
837
838<div class="doc_code"><pre
839>define void @f() gc "name" { ...</pre></div>
840
841<p>The compiler declares the supported values of <i>name</i>. Specifying a
842collector which will cause the compiler to alter its output in order to support
843the named garbage collection algorithm.</p>
844</div>
845
846<!-- ======================================================================= -->
847<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]848 <a name="moduleasm">Module-Level Inline Assembly</a>
849</div>
850
851<div class="doc_text">
852<p>
853Modules may contain "module-level inline asm" blocks, which corresponds to the
854GCC "file scope inline asm" blocks. These blocks are internally concatenated by
855LLVM and treated as a single unit, but may be separated in the .ll file if
856desired. The syntax is very simple:
857</p>
858
859<div class="doc_code">
860<pre>
861module asm "inline asm code goes here"
862module asm "more can go here"
863</pre>
864</div>
865
866<p>The strings can contain any character by escaping non-printable characters.
867 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
868 for the number.
869</p>
870
871<p>
872 The inline asm code is simply printed to the machine code .s file when
873 assembly code is generated.
874</p>
875</div>
876
877<!-- ======================================================================= -->
878<div class="doc_subsection">
879 <a name="datalayout">Data Layout</a>
880</div>
881
882<div class="doc_text">
883<p>A module may specify a target specific data layout string that specifies how
884data is to be laid out in memory. The syntax for the data layout is simply:</p>
885<pre> target datalayout = "<i>layout specification</i>"</pre>
886<p>The <i>layout specification</i> consists of a list of specifications
887separated by the minus sign character ('-'). Each specification starts with a
888letter and may include other information after the letter to define some
889aspect of the data layout. The specifications accepted are as follows: </p>
890<dl>
891 <dt><tt>E</tt></dt>
892 <dd>Specifies that the target lays out data in big-endian form. That is, the
893 bits with the most significance have the lowest address location.</dd>
894 <dt><tt>e</tt></dt>
895 <dd>Specifies that hte target lays out data in little-endian form. That is,
896 the bits with the least significance have the lowest address location.</dd>
897 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
898 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
899 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
900 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
901 too.</dd>
902 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
903 <dd>This specifies the alignment for an integer type of a given bit
904 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
905 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
906 <dd>This specifies the alignment for a vector type of a given bit
907 <i>size</i>.</dd>
908 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
909 <dd>This specifies the alignment for a floating point type of a given bit
910 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
911 (double).</dd>
912 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
913 <dd>This specifies the alignment for an aggregate type of a given bit
914 <i>size</i>.</dd>
915</dl>
916<p>When constructing the data layout for a given target, LLVM starts with a
917default set of specifications which are then (possibly) overriden by the
918specifications in the <tt>datalayout</tt> keyword. The default specifications
919are given in this list:</p>
920<ul>
921 <li><tt>E</tt> - big endian</li>
922 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
923 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
924 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
925 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
926 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
927 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
928 alignment of 64-bits</li>
929 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
930 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
931 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
932 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
933 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
934</ul>
935<p>When llvm is determining the alignment for a given type, it uses the
936following rules:
937<ol>
938 <li>If the type sought is an exact match for one of the specifications, that
939 specification is used.</li>
940 <li>If no match is found, and the type sought is an integer type, then the
941 smallest integer type that is larger than the bitwidth of the sought type is
942 used. If none of the specifications are larger than the bitwidth then the the
943 largest integer type is used. For example, given the default specifications
944 above, the i7 type will use the alignment of i8 (next largest) while both
945 i65 and i256 will use the alignment of i64 (largest specified).</li>
946 <li>If no match is found, and the type sought is a vector type, then the
947 largest vector type that is smaller than the sought vector type will be used
948 as a fall back. This happens because <128 x double> can be implemented in
949 terms of 64 <2 x double>, for example.</li>
950</ol>
951</div>
952
953<!-- *********************************************************************** -->
954<div class="doc_section"> <a name="typesystem">Type System</a> </div>
955<!-- *********************************************************************** -->
956
957<div class="doc_text">
958
959<p>The LLVM type system is one of the most important features of the
960intermediate representation. Being typed enables a number of
961optimizations to be performed on the IR directly, without having to do
962extra analyses on the side before the transformation. A strong type
963system makes it easier to read the generated code and enables novel
964analyses and transformations that are not feasible to perform on normal
965three address code representations.</p>
966
967</div>
968
969<!-- ======================================================================= -->
970<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
971<div class="doc_text">
972<p>The primitive types are the fundamental building blocks of the LLVM
973system. The current set of primitive types is as follows:</p>
974
975<table class="layout">
976 <tr class="layout">
977 <td class="left">
978 <table>
979 <tbody>
980 <tr><th>Type</th><th>Description</th></tr>
981 <tr><td><tt><a name="t_void">void</a></tt></td><td>No value</td></tr>
982 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
983 </tbody>
984 </table>
985 </td>
986 <td class="right">
987 <table>
988 <tbody>
989 <tr><th>Type</th><th>Description</th></tr>
990 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
991 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
992 </tbody>
993 </table>
994 </td>
995 </tr>
996</table>
997</div>
998
999<!-- _______________________________________________________________________ -->
1000<div class="doc_subsubsection"> <a name="t_classifications">Type
1001Classifications</a> </div>
1002<div class="doc_text">
1003<p>These different primitive types fall into a few useful
1004classifications:</p>
1005
1006<table border="1" cellspacing="0" cellpadding="4">
1007 <tbody>
1008 <tr><th>Classification</th><th>Types</th></tr>
1009 <tr>
1010 <td><a name="t_integer">integer</a></td>
1011 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1012 </tr>
1013 <tr>
1014 <td><a name="t_floating">floating point</a></td>
1015 <td><tt>float, double</tt></td>
1016 </tr>
1017 <tr>
1018 <td><a name="t_firstclass">first class</a></td>
1019 <td><tt>i1, ..., float, double, <br/>
1020 <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
1021 </td>
1022 </tr>
1023 </tbody>
1024</table>
1025
1026<p>The <a href="#t_firstclass">first class</a> types are perhaps the
1027most important. Values of these types are the only ones which can be
1028produced by instructions, passed as arguments, or used as operands to
1029instructions. This means that all structures and arrays must be
1030manipulated either by pointer or by component.</p>
1031</div>
1032
1033<!-- ======================================================================= -->
1034<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1035
1036<div class="doc_text">
1037
1038<p>The real power in LLVM comes from the derived types in the system.
1039This is what allows a programmer to represent arrays, functions,
1040pointers, and other useful types. Note that these derived types may be
1041recursive: For example, it is possible to have a two dimensional array.</p>
1042
1043</div>
1044
1045<!-- _______________________________________________________________________ -->
1046<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1047
1048<div class="doc_text">
1049
1050<h5>Overview:</h5>
1051<p>The integer type is a very simple derived type that simply specifies an
1052arbitrary bit width for the integer type desired. Any bit width from 1 bit to
10532^23-1 (about 8 million) can be specified.</p>
1054
1055<h5>Syntax:</h5>
1056
1057<pre>
1058 iN
1059</pre>
1060
1061<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1062value.</p>
1063
1064<h5>Examples:</h5>
1065<table class="layout">
1066 <tr class="layout">
1067 <td class="left">
1068 <tt>i1</tt><br/>
1069 <tt>i4</tt><br/>
1070 <tt>i8</tt><br/>
1071 <tt>i16</tt><br/>
1072 <tt>i32</tt><br/>
1073 <tt>i42</tt><br/>
1074 <tt>i64</tt><br/>
1075 <tt>i1942652</tt><br/>
1076 </td>
1077 <td class="left">
1078 A boolean integer of 1 bit<br/>
1079 A nibble sized integer of 4 bits.<br/>
1080 A byte sized integer of 8 bits.<br/>
1081 A half word sized integer of 16 bits.<br/>
1082 A word sized integer of 32 bits.<br/>
1083 An integer whose bit width is the answer. <br/>
1084 A double word sized integer of 64 bits.<br/>
1085 A really big integer of over 1 million bits.<br/>
1086 </td>
1087 </tr>
1088</table>
1089</div>
1090
1091<!-- _______________________________________________________________________ -->
1092<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1093
1094<div class="doc_text">
1095
1096<h5>Overview:</h5>
1097
1098<p>The array type is a very simple derived type that arranges elements
1099sequentially in memory. The array type requires a size (number of
1100elements) and an underlying data type.</p>
1101
1102<h5>Syntax:</h5>
1103
1104<pre>
1105 [&lt;# elements&gt; x &lt;elementtype&gt;]
1106</pre>
1107
1108<p>The number of elements is a constant integer value; elementtype may
1109be any type with a size.</p>
1110
1111<h5>Examples:</h5>
1112<table class="layout">
1113 <tr class="layout">
1114 <td class="left">
1115 <tt>[40 x i32 ]</tt><br/>
1116 <tt>[41 x i32 ]</tt><br/>
1117 <tt>[40 x i8]</tt><br/>
1118 </td>
1119 <td class="left">
1120 Array of 40 32-bit integer values.<br/>
1121 Array of 41 32-bit integer values.<br/>
1122 Array of 40 8-bit integer values.<br/>
1123 </td>
1124 </tr>
1125</table>
1126<p>Here are some examples of multidimensional arrays:</p>
1127<table class="layout">
1128 <tr class="layout">
1129 <td class="left">
1130 <tt>[3 x [4 x i32]]</tt><br/>
1131 <tt>[12 x [10 x float]]</tt><br/>
1132 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
1133 </td>
1134 <td class="left">
1135 3x4 array of 32-bit integer values.<br/>
1136 12x10 array of single precision floating point values.<br/>
1137 2x3x4 array of 16-bit integer values.<br/>
1138 </td>
1139 </tr>
1140</table>
1141
1142<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1143length array. Normally, accesses past the end of an array are undefined in
1144LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1145As a special case, however, zero length arrays are recognized to be variable
1146length. This allows implementation of 'pascal style arrays' with the LLVM
1147type "{ i32, [0 x float]}", for example.</p>
1148
1149</div>
1150
1151<!-- _______________________________________________________________________ -->
1152<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1153<div class="doc_text">
1154<h5>Overview:</h5>
1155<p>The function type can be thought of as a function signature. It
1156consists of a return type and a list of formal parameter types.
1157Function types are usually used to build virtual function tables
1158(which are structures of pointers to functions), for indirect function
1159calls, and when defining a function.</p>
1160<p>
1161The return type of a function type cannot be an aggregate type.
1162</p>
1163<h5>Syntax:</h5>
1164<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
1165<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
1166specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1167which indicates that the function takes a variable number of arguments.
1168Variable argument functions can access their arguments with the <a
1169 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
1170<h5>Examples:</h5>
1171<table class="layout">
1172 <tr class="layout">
1173 <td class="left"><tt>i32 (i32)</tt></td>
1174 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1175 </td>
1176 </tr><tr class="layout">
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]1177 <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1178 </tt></td>
1179 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1180 an <tt>i16</tt> that should be sign extended and a
1181 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1182 <tt>float</tt>.
1183 </td>
1184 </tr><tr class="layout">
1185 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1186 <td class="left">A vararg function that takes at least one
1187 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1188 which returns an integer. This is the signature for <tt>printf</tt> in
1189 LLVM.
1190 </td>
1191 </tr>
1192</table>
1193
1194</div>
1195<!-- _______________________________________________________________________ -->
1196<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1197<div class="doc_text">
1198<h5>Overview:</h5>
1199<p>The structure type is used to represent a collection of data members
1200together in memory. The packing of the field types is defined to match
1201the ABI of the underlying processor. The elements of a structure may
1202be any type that has a size.</p>
1203<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1204and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1205field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1206instruction.</p>
1207<h5>Syntax:</h5>
1208<pre> { &lt;type list&gt; }<br></pre>
1209<h5>Examples:</h5>
1210<table class="layout">
1211 <tr class="layout">
1212 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1213 <td class="left">A triple of three <tt>i32</tt> values</td>
1214 </tr><tr class="layout">
1215 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1216 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1217 second element is a <a href="#t_pointer">pointer</a> to a
1218 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1219 an <tt>i32</tt>.</td>
1220 </tr>
1221</table>
1222</div>
1223
1224<!-- _______________________________________________________________________ -->
1225<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1226</div>
1227<div class="doc_text">
1228<h5>Overview:</h5>
1229<p>The packed structure type is used to represent a collection of data members
1230together in memory. There is no padding between fields. Further, the alignment
1231of a packed structure is 1 byte. The elements of a packed structure may
1232be any type that has a size.</p>
1233<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1234and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1235field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1236instruction.</p>
1237<h5>Syntax:</h5>
1238<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1239<h5>Examples:</h5>
1240<table class="layout">
1241 <tr class="layout">
1242 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1243 <td class="left">A triple of three <tt>i32</tt> values</td>
1244 </tr><tr class="layout">
1245 <td class="left"><tt>&lt;&nbsp;{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}&nbsp;&gt;</tt></td>
1246 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1247 second element is a <a href="#t_pointer">pointer</a> to a
1248 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1249 an <tt>i32</tt>.</td>
1250 </tr>
1251</table>
1252</div>
1253
1254<!-- _______________________________________________________________________ -->
1255<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1256<div class="doc_text">
1257<h5>Overview:</h5>
1258<p>As in many languages, the pointer type represents a pointer or
1259reference to another object, which must live in memory.</p>
1260<h5>Syntax:</h5>
1261<pre> &lt;type&gt; *<br></pre>
1262<h5>Examples:</h5>
1263<table class="layout">
1264 <tr class="layout">
1265 <td class="left">
1266 <tt>[4x i32]*</tt><br/>
1267 <tt>i32 (i32 *) *</tt><br/>
1268 </td>
1269 <td class="left">
1270 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
1271 four <tt>i32</tt> values<br/>
1272 A <a href="#t_pointer">pointer</a> to a <a
1273 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1274 <tt>i32</tt>.<br/>
1275 </td>
1276 </tr>
1277</table>
1278</div>
1279
1280<!-- _______________________________________________________________________ -->
1281<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1282<div class="doc_text">
1283
1284<h5>Overview:</h5>
1285
1286<p>A vector type is a simple derived type that represents a vector
1287of elements. Vector types are used when multiple primitive data
1288are operated in parallel using a single instruction (SIMD).
1289A vector type requires a size (number of
1290elements) and an underlying primitive data type. Vectors must have a power
1291of two length (1, 2, 4, 8, 16 ...). Vector types are
1292considered <a href="#t_firstclass">first class</a>.</p>
1293
1294<h5>Syntax:</h5>
1295
1296<pre>
1297 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1298</pre>
1299
1300<p>The number of elements is a constant integer value; elementtype may
1301be any integer or floating point type.</p>
1302
1303<h5>Examples:</h5>
1304
1305<table class="layout">
1306 <tr class="layout">
1307 <td class="left">
1308 <tt>&lt;4 x i32&gt;</tt><br/>
1309 <tt>&lt;8 x float&gt;</tt><br/>
1310 <tt>&lt;2 x i64&gt;</tt><br/>
1311 </td>
1312 <td class="left">
1313 Vector of 4 32-bit integer values.<br/>
1314 Vector of 8 floating-point values.<br/>
1315 Vector of 2 64-bit integer values.<br/>
1316 </td>
1317 </tr>
1318</table>
1319</div>
1320
1321<!-- _______________________________________________________________________ -->
1322<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1323<div class="doc_text">
1324
1325<h5>Overview:</h5>
1326
1327<p>Opaque types are used to represent unknown types in the system. This
Gordon Henriksenda0706e2007-10-14 00:34:53 +0000[diff] [blame]1328corresponds (for example) to the C notion of a forward declared structure type.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1329In LLVM, opaque types can eventually be resolved to any type (not just a
1330structure type).</p>
1331
1332<h5>Syntax:</h5>
1333
1334<pre>
1335 opaque
1336</pre>
1337
1338<h5>Examples:</h5>
1339
1340<table class="layout">
1341 <tr class="layout">
1342 <td class="left">
1343 <tt>opaque</tt>
1344 </td>
1345 <td class="left">
1346 An opaque type.<br/>
1347 </td>
1348 </tr>
1349</table>
1350</div>
1351
1352
1353<!-- *********************************************************************** -->
1354<div class="doc_section"> <a name="constants">Constants</a> </div>
1355<!-- *********************************************************************** -->
1356
1357<div class="doc_text">
1358
1359<p>LLVM has several different basic types of constants. This section describes
1360them all and their syntax.</p>
1361
1362</div>
1363
1364<!-- ======================================================================= -->
1365<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1366
1367<div class="doc_text">
1368
1369<dl>
1370 <dt><b>Boolean constants</b></dt>
1371
1372 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1373 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1374 </dd>
1375
1376 <dt><b>Integer constants</b></dt>
1377
1378 <dd>Standard integers (such as '4') are constants of the <a
1379 href="#t_integer">integer</a> type. Negative numbers may be used with
1380 integer types.
1381 </dd>
1382
1383 <dt><b>Floating point constants</b></dt>
1384
1385 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1386 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
1387 notation (see below). Floating point constants must have a <a
1388 href="#t_floating">floating point</a> type. </dd>
1389
1390 <dt><b>Null pointer constants</b></dt>
1391
1392 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1393 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1394
1395</dl>
1396
1397<p>The one non-intuitive notation for constants is the optional hexadecimal form
1398of floating point constants. For example, the form '<tt>double
13990x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
14004.5e+15</tt>'. The only time hexadecimal floating point constants are required
1401(and the only time that they are generated by the disassembler) is when a
1402floating point constant must be emitted but it cannot be represented as a
1403decimal floating point number. For example, NaN's, infinities, and other
1404special values are represented in their IEEE hexadecimal format so that
1405assembly and disassembly do not cause any bits to change in the constants.</p>
1406
1407</div>
1408
1409<!-- ======================================================================= -->
1410<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1411</div>
1412
1413<div class="doc_text">
1414<p>Aggregate constants arise from aggregation of simple constants
1415and smaller aggregate constants.</p>
1416
1417<dl>
1418 <dt><b>Structure constants</b></dt>
1419
1420 <dd>Structure constants are represented with notation similar to structure
1421 type definitions (a comma separated list of elements, surrounded by braces
1422 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1423 where "<tt>%G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
1424 must have <a href="#t_struct">structure type</a>, and the number and
1425 types of elements must match those specified by the type.
1426 </dd>
1427
1428 <dt><b>Array constants</b></dt>
1429
1430 <dd>Array constants are represented with notation similar to array type
1431 definitions (a comma separated list of elements, surrounded by square brackets
1432 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1433 constants must have <a href="#t_array">array type</a>, and the number and
1434 types of elements must match those specified by the type.
1435 </dd>
1436
1437 <dt><b>Vector constants</b></dt>
1438
1439 <dd>Vector constants are represented with notation similar to vector type
1440 definitions (a comma separated list of elements, surrounded by
1441 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1442 i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must have <a
1443 href="#t_vector">vector type</a>, and the number and types of elements must
1444 match those specified by the type.
1445 </dd>
1446
1447 <dt><b>Zero initialization</b></dt>
1448
1449 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1450 value to zero of <em>any</em> type, including scalar and aggregate types.
1451 This is often used to avoid having to print large zero initializers (e.g. for
1452 large arrays) and is always exactly equivalent to using explicit zero
1453 initializers.
1454 </dd>
1455</dl>
1456
1457</div>
1458
1459<!-- ======================================================================= -->
1460<div class="doc_subsection">
1461 <a name="globalconstants">Global Variable and Function Addresses</a>
1462</div>
1463
1464<div class="doc_text">
1465
1466<p>The addresses of <a href="#globalvars">global variables</a> and <a
1467href="#functionstructure">functions</a> are always implicitly valid (link-time)
1468constants. These constants are explicitly referenced when the <a
1469href="#identifiers">identifier for the global</a> is used and always have <a
1470href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1471file:</p>
1472
1473<div class="doc_code">
1474<pre>
1475@X = global i32 17
1476@Y = global i32 42
1477@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1478</pre>
1479</div>
1480
1481</div>
1482
1483<!-- ======================================================================= -->
1484<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1485<div class="doc_text">
1486 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1487 no specific value. Undefined values may be of any type and be used anywhere
1488 a constant is permitted.</p>
1489
1490 <p>Undefined values indicate to the compiler that the program is well defined
1491 no matter what value is used, giving the compiler more freedom to optimize.
1492 </p>
1493</div>
1494
1495<!-- ======================================================================= -->
1496<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1497</div>
1498
1499<div class="doc_text">
1500
1501<p>Constant expressions are used to allow expressions involving other constants
1502to be used as constants. Constant expressions may be of any <a
1503href="#t_firstclass">first class</a> type and may involve any LLVM operation
1504that does not have side effects (e.g. load and call are not supported). The
1505following is the syntax for constant expressions:</p>
1506
1507<dl>
1508 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1509 <dd>Truncate a constant to another type. The bit size of CST must be larger
1510 than the bit size of TYPE. Both types must be integers.</dd>
1511
1512 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1513 <dd>Zero extend a constant to another type. The bit size of CST must be
1514 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1515
1516 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1517 <dd>Sign extend a constant to another type. The bit size of CST must be
1518 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1519
1520 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1521 <dd>Truncate a floating point constant to another floating point type. The
1522 size of CST must be larger than the size of TYPE. Both types must be
1523 floating point.</dd>
1524
1525 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1526 <dd>Floating point extend a constant to another type. The size of CST must be
1527 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1528
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]1529 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1530 <dd>Convert a floating point constant to the corresponding unsigned integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1531 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1532 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1533 of the same number of elements. If the value won't fit in the integer type,
1534 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1535
1536 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1537 <dd>Convert a floating point constant to the corresponding signed integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1538 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1539 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1540 of the same number of elements. If the value won't fit in the integer type,
1541 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1542
1543 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1544 <dd>Convert an unsigned integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1545 constant. TYPE must be a scalar or vector floating point type. CST must be of
1546 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1547 of the same number of elements. If the value won't fit in the floating point
1548 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1549
1550 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
1551 <dd>Convert a signed integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1552 constant. TYPE must be a scalar or vector floating point type. CST must be of
1553 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1554 of the same number of elements. If the value won't fit in the floating point
1555 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1556
1557 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1558 <dd>Convert a pointer typed constant to the corresponding integer constant
1559 TYPE must be an integer type. CST must be of pointer type. The CST value is
1560 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1561
1562 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1563 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1564 pointer type. CST must be of integer type. The CST value is zero extended,
1565 truncated, or unchanged to make it fit in a pointer size. This one is
1566 <i>really</i> dangerous!</dd>
1567
1568 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
1569 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1570 identical (same number of bits). The conversion is done as if the CST value
1571 was stored to memory and read back as TYPE. In other words, no bits change
1572 with this operator, just the type. This can be used for conversion of
1573 vector types to any other type, as long as they have the same bit width. For
1574 pointers it is only valid to cast to another pointer type.
1575 </dd>
1576
1577 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1578
1579 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1580 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1581 instruction, the index list may have zero or more indexes, which are required
1582 to make sense for the type of "CSTPTR".</dd>
1583
1584 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1585
1586 <dd>Perform the <a href="#i_select">select operation</a> on
1587 constants.</dd>
1588
1589 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1590 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1591
1592 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1593 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
1594
1595 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1596
1597 <dd>Perform the <a href="#i_extractelement">extractelement
1598 operation</a> on constants.
1599
1600 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1601
1602 <dd>Perform the <a href="#i_insertelement">insertelement
1603 operation</a> on constants.</dd>
1604
1605
1606 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1607
1608 <dd>Perform the <a href="#i_shufflevector">shufflevector
1609 operation</a> on constants.</dd>
1610
1611 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1612
1613 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1614 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
1615 binary</a> operations. The constraints on operands are the same as those for
1616 the corresponding instruction (e.g. no bitwise operations on floating point
1617 values are allowed).</dd>
1618</dl>
1619</div>
1620
1621<!-- *********************************************************************** -->
1622<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1623<!-- *********************************************************************** -->
1624
1625<!-- ======================================================================= -->
1626<div class="doc_subsection">
1627<a name="inlineasm">Inline Assembler Expressions</a>
1628</div>
1629
1630<div class="doc_text">
1631
1632<p>
1633LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1634Module-Level Inline Assembly</a>) through the use of a special value. This
1635value represents the inline assembler as a string (containing the instructions
1636to emit), a list of operand constraints (stored as a string), and a flag that
1637indicates whether or not the inline asm expression has side effects. An example
1638inline assembler expression is:
1639</p>
1640
1641<div class="doc_code">
1642<pre>
1643i32 (i32) asm "bswap $0", "=r,r"
1644</pre>
1645</div>
1646
1647<p>
1648Inline assembler expressions may <b>only</b> be used as the callee operand of
1649a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1650</p>
1651
1652<div class="doc_code">
1653<pre>
1654%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
1655</pre>
1656</div>
1657
1658<p>
1659Inline asms with side effects not visible in the constraint list must be marked
1660as having side effects. This is done through the use of the
1661'<tt>sideeffect</tt>' keyword, like so:
1662</p>
1663
1664<div class="doc_code">
1665<pre>
1666call void asm sideeffect "eieio", ""()
1667</pre>
1668</div>
1669
1670<p>TODO: The format of the asm and constraints string still need to be
1671documented here. Constraints on what can be done (e.g. duplication, moving, etc
1672need to be documented).
1673</p>
1674
1675</div>
1676
1677<!-- *********************************************************************** -->
1678<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1679<!-- *********************************************************************** -->
1680
1681<div class="doc_text">
1682
1683<p>The LLVM instruction set consists of several different
1684classifications of instructions: <a href="#terminators">terminator
1685instructions</a>, <a href="#binaryops">binary instructions</a>,
1686<a href="#bitwiseops">bitwise binary instructions</a>, <a
1687 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1688instructions</a>.</p>
1689
1690</div>
1691
1692<!-- ======================================================================= -->
1693<div class="doc_subsection"> <a name="terminators">Terminator
1694Instructions</a> </div>
1695
1696<div class="doc_text">
1697
1698<p>As mentioned <a href="#functionstructure">previously</a>, every
1699basic block in a program ends with a "Terminator" instruction, which
1700indicates which block should be executed after the current block is
1701finished. These terminator instructions typically yield a '<tt>void</tt>'
1702value: they produce control flow, not values (the one exception being
1703the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
1704<p>There are six different terminator instructions: the '<a
1705 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1706instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
1707the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1708 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1709 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
1710
1711</div>
1712
1713<!-- _______________________________________________________________________ -->
1714<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1715Instruction</a> </div>
1716<div class="doc_text">
1717<h5>Syntax:</h5>
1718<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
1719 ret void <i>; Return from void function</i>
1720</pre>
1721<h5>Overview:</h5>
1722<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1723value) from a function back to the caller.</p>
1724<p>There are two forms of the '<tt>ret</tt>' instruction: one that
1725returns a value and then causes control flow, and one that just causes
1726control flow to occur.</p>
1727<h5>Arguments:</h5>
1728<p>The '<tt>ret</tt>' instruction may return any '<a
1729 href="#t_firstclass">first class</a>' type. Notice that a function is
1730not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1731instruction inside of the function that returns a value that does not
1732match the return type of the function.</p>
1733<h5>Semantics:</h5>
1734<p>When the '<tt>ret</tt>' instruction is executed, control flow
1735returns back to the calling function's context. If the caller is a "<a
1736 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
1737the instruction after the call. If the caller was an "<a
1738 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1739at the beginning of the "normal" destination block. If the instruction
1740returns a value, that value shall set the call or invoke instruction's
1741return value.</p>
1742<h5>Example:</h5>
1743<pre> ret i32 5 <i>; Return an integer value of 5</i>
1744 ret void <i>; Return from a void function</i>
1745</pre>
1746</div>
1747<!-- _______________________________________________________________________ -->
1748<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
1749<div class="doc_text">
1750<h5>Syntax:</h5>
1751<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
1752</pre>
1753<h5>Overview:</h5>
1754<p>The '<tt>br</tt>' instruction is used to cause control flow to
1755transfer to a different basic block in the current function. There are
1756two forms of this instruction, corresponding to a conditional branch
1757and an unconditional branch.</p>
1758<h5>Arguments:</h5>
1759<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1760single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
1761unconditional form of the '<tt>br</tt>' instruction takes a single
1762'<tt>label</tt>' value as a target.</p>
1763<h5>Semantics:</h5>
1764<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
1765argument is evaluated. If the value is <tt>true</tt>, control flows
1766to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1767control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
1768<h5>Example:</h5>
1769<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
1770 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
1771</div>
1772<!-- _______________________________________________________________________ -->
1773<div class="doc_subsubsection">
1774 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1775</div>
1776
1777<div class="doc_text">
1778<h5>Syntax:</h5>
1779
1780<pre>
1781 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1782</pre>
1783
1784<h5>Overview:</h5>
1785
1786<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1787several different places. It is a generalization of the '<tt>br</tt>'
1788instruction, allowing a branch to occur to one of many possible
1789destinations.</p>
1790
1791
1792<h5>Arguments:</h5>
1793
1794<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1795comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1796an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1797table is not allowed to contain duplicate constant entries.</p>
1798
1799<h5>Semantics:</h5>
1800
1801<p>The <tt>switch</tt> instruction specifies a table of values and
1802destinations. When the '<tt>switch</tt>' instruction is executed, this
1803table is searched for the given value. If the value is found, control flow is
1804transfered to the corresponding destination; otherwise, control flow is
1805transfered to the default destination.</p>
1806
1807<h5>Implementation:</h5>
1808
1809<p>Depending on properties of the target machine and the particular
1810<tt>switch</tt> instruction, this instruction may be code generated in different
1811ways. For example, it could be generated as a series of chained conditional
1812branches or with a lookup table.</p>
1813
1814<h5>Example:</h5>
1815
1816<pre>
1817 <i>; Emulate a conditional br instruction</i>
1818 %Val = <a href="#i_zext">zext</a> i1 %value to i32
1819 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
1820
1821 <i>; Emulate an unconditional br instruction</i>
1822 switch i32 0, label %dest [ ]
1823
1824 <i>; Implement a jump table:</i>
1825 switch i32 %val, label %otherwise [ i32 0, label %onzero
1826 i32 1, label %onone
1827 i32 2, label %ontwo ]
1828</pre>
1829</div>
1830
1831<!-- _______________________________________________________________________ -->
1832<div class="doc_subsubsection">
1833 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1834</div>
1835
1836<div class="doc_text">
1837
1838<h5>Syntax:</h5>
1839
1840<pre>
1841 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1842 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
1843</pre>
1844
1845<h5>Overview:</h5>
1846
1847<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1848function, with the possibility of control flow transfer to either the
1849'<tt>normal</tt>' label or the
1850'<tt>exception</tt>' label. If the callee function returns with the
1851"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1852"normal" label. If the callee (or any indirect callees) returns with the "<a
1853href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1854continued at the dynamically nearest "exception" label.</p>
1855
1856<h5>Arguments:</h5>
1857
1858<p>This instruction requires several arguments:</p>
1859
1860<ol>
1861 <li>
1862 The optional "cconv" marker indicates which <a href="#callingconv">calling
1863 convention</a> the call should use. If none is specified, the call defaults
1864 to using C calling conventions.
1865 </li>
1866 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1867 function value being invoked. In most cases, this is a direct function
1868 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1869 an arbitrary pointer to function value.
1870 </li>
1871
1872 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1873 function to be invoked. </li>
1874
1875 <li>'<tt>function args</tt>': argument list whose types match the function
1876 signature argument types. If the function signature indicates the function
1877 accepts a variable number of arguments, the extra arguments can be
1878 specified. </li>
1879
1880 <li>'<tt>normal label</tt>': the label reached when the called function
1881 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1882
1883 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1884 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1885
1886</ol>
1887
1888<h5>Semantics:</h5>
1889
1890<p>This instruction is designed to operate as a standard '<tt><a
1891href="#i_call">call</a></tt>' instruction in most regards. The primary
1892difference is that it establishes an association with a label, which is used by
1893the runtime library to unwind the stack.</p>
1894
1895<p>This instruction is used in languages with destructors to ensure that proper
1896cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1897exception. Additionally, this is important for implementation of
1898'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1899
1900<h5>Example:</h5>
1901<pre>
1902 %retval = invoke i32 %Test(i32 15) to label %Continue
1903 unwind label %TestCleanup <i>; {i32}:retval set</i>
1904 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1905 unwind label %TestCleanup <i>; {i32}:retval set</i>
1906</pre>
1907</div>
1908
1909
1910<!-- _______________________________________________________________________ -->
1911
1912<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1913Instruction</a> </div>
1914
1915<div class="doc_text">
1916
1917<h5>Syntax:</h5>
1918<pre>
1919 unwind
1920</pre>
1921
1922<h5>Overview:</h5>
1923
1924<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1925at the first callee in the dynamic call stack which used an <a
1926href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1927primarily used to implement exception handling.</p>
1928
1929<h5>Semantics:</h5>
1930
1931<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1932immediately halt. The dynamic call stack is then searched for the first <a
1933href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1934execution continues at the "exceptional" destination block specified by the
1935<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1936dynamic call chain, undefined behavior results.</p>
1937</div>
1938
1939<!-- _______________________________________________________________________ -->
1940
1941<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1942Instruction</a> </div>
1943
1944<div class="doc_text">
1945
1946<h5>Syntax:</h5>
1947<pre>
1948 unreachable
1949</pre>
1950
1951<h5>Overview:</h5>
1952
1953<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1954instruction is used to inform the optimizer that a particular portion of the
1955code is not reachable. This can be used to indicate that the code after a
1956no-return function cannot be reached, and other facts.</p>
1957
1958<h5>Semantics:</h5>
1959
1960<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1961</div>
1962
1963
1964
1965<!-- ======================================================================= -->
1966<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
1967<div class="doc_text">
1968<p>Binary operators are used to do most of the computation in a
1969program. They require two operands, execute an operation on them, and
1970produce a single value. The operands might represent
1971multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
1972The result value of a binary operator is not
1973necessarily the same type as its operands.</p>
1974<p>There are several different binary operators:</p>
1975</div>
1976<!-- _______________________________________________________________________ -->
1977<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1978Instruction</a> </div>
1979<div class="doc_text">
1980<h5>Syntax:</h5>
1981<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1982</pre>
1983<h5>Overview:</h5>
1984<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
1985<h5>Arguments:</h5>
1986<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
1987 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1988 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
1989Both arguments must have identical types.</p>
1990<h5>Semantics:</h5>
1991<p>The value produced is the integer or floating point sum of the two
1992operands.</p>
1993<h5>Example:</h5>
1994<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
1995</pre>
1996</div>
1997<!-- _______________________________________________________________________ -->
1998<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1999Instruction</a> </div>
2000<div class="doc_text">
2001<h5>Syntax:</h5>
2002<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2003</pre>
2004<h5>Overview:</h5>
2005<p>The '<tt>sub</tt>' instruction returns the difference of its two
2006operands.</p>
2007<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
2008instruction present in most other intermediate representations.</p>
2009<h5>Arguments:</h5>
2010<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
2011 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2012values.
2013This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2014Both arguments must have identical types.</p>
2015<h5>Semantics:</h5>
2016<p>The value produced is the integer or floating point difference of
2017the two operands.</p>
2018<h5>Example:</h5>
2019<pre>
2020 &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2021 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2022</pre>
2023</div>
2024<!-- _______________________________________________________________________ -->
2025<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
2026Instruction</a> </div>
2027<div class="doc_text">
2028<h5>Syntax:</h5>
2029<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2030</pre>
2031<h5>Overview:</h5>
2032<p>The '<tt>mul</tt>' instruction returns the product of its two
2033operands.</p>
2034<h5>Arguments:</h5>
2035<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
2036 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2037values.
2038This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2039Both arguments must have identical types.</p>
2040<h5>Semantics:</h5>
2041<p>The value produced is the integer or floating point product of the
2042two operands.</p>
2043<p>Because the operands are the same width, the result of an integer
2044multiplication is the same whether the operands should be deemed unsigned or
2045signed.</p>
2046<h5>Example:</h5>
2047<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2048</pre>
2049</div>
2050<!-- _______________________________________________________________________ -->
2051<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2052</a></div>
2053<div class="doc_text">
2054<h5>Syntax:</h5>
2055<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2056</pre>
2057<h5>Overview:</h5>
2058<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2059operands.</p>
2060<h5>Arguments:</h5>
2061<p>The two arguments to the '<tt>udiv</tt>' instruction must be
2062<a href="#t_integer">integer</a> values. Both arguments must have identical
2063types. This instruction can also take <a href="#t_vector">vector</a> versions
2064of the values in which case the elements must be integers.</p>
2065<h5>Semantics:</h5>
2066<p>The value produced is the unsigned integer quotient of the two operands. This
2067instruction always performs an unsigned division operation, regardless of
2068whether the arguments are unsigned or not.</p>
2069<h5>Example:</h5>
2070<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2071</pre>
2072</div>
2073<!-- _______________________________________________________________________ -->
2074<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2075</a> </div>
2076<div class="doc_text">
2077<h5>Syntax:</h5>
2078<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2079</pre>
2080<h5>Overview:</h5>
2081<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2082operands.</p>
2083<h5>Arguments:</h5>
2084<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2085<a href="#t_integer">integer</a> values. Both arguments must have identical
2086types. This instruction can also take <a href="#t_vector">vector</a> versions
2087of the values in which case the elements must be integers.</p>
2088<h5>Semantics:</h5>
2089<p>The value produced is the signed integer quotient of the two operands. This
2090instruction always performs a signed division operation, regardless of whether
2091the arguments are signed or not.</p>
2092<h5>Example:</h5>
2093<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2094</pre>
2095</div>
2096<!-- _______________________________________________________________________ -->
2097<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2098Instruction</a> </div>
2099<div class="doc_text">
2100<h5>Syntax:</h5>
2101<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2102</pre>
2103<h5>Overview:</h5>
2104<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2105operands.</p>
2106<h5>Arguments:</h5>
2107<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2108<a href="#t_floating">floating point</a> values. Both arguments must have
2109identical types. This instruction can also take <a href="#t_vector">vector</a>
2110versions of floating point values.</p>
2111<h5>Semantics:</h5>
2112<p>The value produced is the floating point quotient of the two operands.</p>
2113<h5>Example:</h5>
2114<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2115</pre>
2116</div>
2117<!-- _______________________________________________________________________ -->
2118<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2119</div>
2120<div class="doc_text">
2121<h5>Syntax:</h5>
2122<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2123</pre>
2124<h5>Overview:</h5>
2125<p>The '<tt>urem</tt>' instruction returns the remainder from the
2126unsigned division of its two arguments.</p>
2127<h5>Arguments:</h5>
2128<p>The two arguments to the '<tt>urem</tt>' instruction must be
2129<a href="#t_integer">integer</a> values. Both arguments must have identical
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2130types. This instruction can also take <a href="#t_vector">vector</a> versions
2131of the values in which case the elements must be integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2132<h5>Semantics:</h5>
2133<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
2134This instruction always performs an unsigned division to get the remainder,
2135regardless of whether the arguments are unsigned or not.</p>
2136<h5>Example:</h5>
2137<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2138</pre>
2139
2140</div>
2141<!-- _______________________________________________________________________ -->
2142<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
2143Instruction</a> </div>
2144<div class="doc_text">
2145<h5>Syntax:</h5>
2146<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2147</pre>
2148<h5>Overview:</h5>
2149<p>The '<tt>srem</tt>' instruction returns the remainder from the
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2150signed division of its two operands. This instruction can also take
2151<a href="#t_vector">vector</a> versions of the values in which case
2152the elements must be integers.</p>
2153</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2154<h5>Arguments:</h5>
2155<p>The two arguments to the '<tt>srem</tt>' instruction must be
2156<a href="#t_integer">integer</a> values. Both arguments must have identical
2157types.</p>
2158<h5>Semantics:</h5>
2159<p>This instruction returns the <i>remainder</i> of a division (where the result
2160has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2161operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2162a value. For more information about the difference, see <a
2163 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2164Math Forum</a>. For a table of how this is implemented in various languages,
2165please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2166Wikipedia: modulo operation</a>.</p>
2167<h5>Example:</h5>
2168<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2169</pre>
2170
2171</div>
2172<!-- _______________________________________________________________________ -->
2173<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2174Instruction</a> </div>
2175<div class="doc_text">
2176<h5>Syntax:</h5>
2177<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2178</pre>
2179<h5>Overview:</h5>
2180<p>The '<tt>frem</tt>' instruction returns the remainder from the
2181division of its two operands.</p>
2182<h5>Arguments:</h5>
2183<p>The two arguments to the '<tt>frem</tt>' instruction must be
2184<a href="#t_floating">floating point</a> values. Both arguments must have
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2185identical types. This instruction can also take <a href="#t_vector">vector</a>
2186versions of floating point values.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2187<h5>Semantics:</h5>
2188<p>This instruction returns the <i>remainder</i> of a division.</p>
2189<h5>Example:</h5>
2190<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2191</pre>
2192</div>
2193
2194<!-- ======================================================================= -->
2195<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2196Operations</a> </div>
2197<div class="doc_text">
2198<p>Bitwise binary operators are used to do various forms of
2199bit-twiddling in a program. They are generally very efficient
2200instructions and can commonly be strength reduced from other
2201instructions. They require two operands, execute an operation on them,
2202and produce a single value. The resulting value of the bitwise binary
2203operators is always the same type as its first operand.</p>
2204</div>
2205
2206<!-- _______________________________________________________________________ -->
2207<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2208Instruction</a> </div>
2209<div class="doc_text">
2210<h5>Syntax:</h5>
2211<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2212</pre>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2213
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2214<h5>Overview:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2215
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2216<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2217the left a specified number of bits.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2218
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2219<h5>Arguments:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2220
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2221<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2222 href="#t_integer">integer</a> type.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2223
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2224<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2225
2226<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>. If
2227<tt>var2</tt> is (statically or dynamically) equal to or larger than the number
2228of bits in <tt>var1</tt>, the result is undefined.</p>
2229
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2230<h5>Example:</h5><pre>
2231 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2232 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2233 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2234 &lt;result&gt; = shl i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2235</pre>
2236</div>
2237<!-- _______________________________________________________________________ -->
2238<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2239Instruction</a> </div>
2240<div class="doc_text">
2241<h5>Syntax:</h5>
2242<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2243</pre>
2244
2245<h5>Overview:</h5>
2246<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2247operand shifted to the right a specified number of bits with zero fill.</p>
2248
2249<h5>Arguments:</h5>
2250<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2251<a href="#t_integer">integer</a> type.</p>
2252
2253<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2254
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2255<p>This instruction always performs a logical shift right operation. The most
2256significant bits of the result will be filled with zero bits after the
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2257shift. If <tt>var2</tt> is (statically or dynamically) equal to or larger than
2258the number of bits in <tt>var1</tt>, the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2259
2260<h5>Example:</h5>
2261<pre>
2262 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2263 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2264 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2265 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2266 &lt;result&gt; = lshr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2267</pre>
2268</div>
2269
2270<!-- _______________________________________________________________________ -->
2271<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2272Instruction</a> </div>
2273<div class="doc_text">
2274
2275<h5>Syntax:</h5>
2276<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2277</pre>
2278
2279<h5>Overview:</h5>
2280<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2281operand shifted to the right a specified number of bits with sign extension.</p>
2282
2283<h5>Arguments:</h5>
2284<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2285<a href="#t_integer">integer</a> type.</p>
2286
2287<h5>Semantics:</h5>
2288<p>This instruction always performs an arithmetic shift right operation,
2289The most significant bits of the result will be filled with the sign bit
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2290of <tt>var1</tt>. If <tt>var2</tt> is (statically or dynamically) equal to or
2291larger than the number of bits in <tt>var1</tt>, the result is undefined.
2292</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2293
2294<h5>Example:</h5>
2295<pre>
2296 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2297 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2298 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2299 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2300 &lt;result&gt; = ashr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2301</pre>
2302</div>
2303
2304<!-- _______________________________________________________________________ -->
2305<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2306Instruction</a> </div>
2307<div class="doc_text">
2308<h5>Syntax:</h5>
2309<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2310</pre>
2311<h5>Overview:</h5>
2312<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2313its two operands.</p>
2314<h5>Arguments:</h5>
2315<p>The two arguments to the '<tt>and</tt>' instruction must be <a
2316 href="#t_integer">integer</a> values. Both arguments must have
2317identical types.</p>
2318<h5>Semantics:</h5>
2319<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
2320<p> </p>
2321<div style="align: center">
2322<table border="1" cellspacing="0" cellpadding="4">
2323 <tbody>
2324 <tr>
2325 <td>In0</td>
2326 <td>In1</td>
2327 <td>Out</td>
2328 </tr>
2329 <tr>
2330 <td>0</td>
2331 <td>0</td>
2332 <td>0</td>
2333 </tr>
2334 <tr>
2335 <td>0</td>
2336 <td>1</td>
2337 <td>0</td>
2338 </tr>
2339 <tr>
2340 <td>1</td>
2341 <td>0</td>
2342 <td>0</td>
2343 </tr>
2344 <tr>
2345 <td>1</td>
2346 <td>1</td>
2347 <td>1</td>
2348 </tr>
2349 </tbody>
2350</table>
2351</div>
2352<h5>Example:</h5>
2353<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2354 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2355 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
2356</pre>
2357</div>
2358<!-- _______________________________________________________________________ -->
2359<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
2360<div class="doc_text">
2361<h5>Syntax:</h5>
2362<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2363</pre>
2364<h5>Overview:</h5>
2365<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2366or of its two operands.</p>
2367<h5>Arguments:</h5>
2368<p>The two arguments to the '<tt>or</tt>' instruction must be <a
2369 href="#t_integer">integer</a> values. Both arguments must have
2370identical types.</p>
2371<h5>Semantics:</h5>
2372<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
2373<p> </p>
2374<div style="align: center">
2375<table border="1" cellspacing="0" cellpadding="4">
2376 <tbody>
2377 <tr>
2378 <td>In0</td>
2379 <td>In1</td>
2380 <td>Out</td>
2381 </tr>
2382 <tr>
2383 <td>0</td>
2384 <td>0</td>
2385 <td>0</td>
2386 </tr>
2387 <tr>
2388 <td>0</td>
2389 <td>1</td>
2390 <td>1</td>
2391 </tr>
2392 <tr>
2393 <td>1</td>
2394 <td>0</td>
2395 <td>1</td>
2396 </tr>
2397 <tr>
2398 <td>1</td>
2399 <td>1</td>
2400 <td>1</td>
2401 </tr>
2402 </tbody>
2403</table>
2404</div>
2405<h5>Example:</h5>
2406<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2407 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2408 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
2409</pre>
2410</div>
2411<!-- _______________________________________________________________________ -->
2412<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2413Instruction</a> </div>
2414<div class="doc_text">
2415<h5>Syntax:</h5>
2416<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2417</pre>
2418<h5>Overview:</h5>
2419<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2420or of its two operands. The <tt>xor</tt> is used to implement the
2421"one's complement" operation, which is the "~" operator in C.</p>
2422<h5>Arguments:</h5>
2423<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
2424 href="#t_integer">integer</a> values. Both arguments must have
2425identical types.</p>
2426<h5>Semantics:</h5>
2427<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
2428<p> </p>
2429<div style="align: center">
2430<table border="1" cellspacing="0" cellpadding="4">
2431 <tbody>
2432 <tr>
2433 <td>In0</td>
2434 <td>In1</td>
2435 <td>Out</td>
2436 </tr>
2437 <tr>
2438 <td>0</td>
2439 <td>0</td>
2440 <td>0</td>
2441 </tr>
2442 <tr>
2443 <td>0</td>
2444 <td>1</td>
2445 <td>1</td>
2446 </tr>
2447 <tr>
2448 <td>1</td>
2449 <td>0</td>
2450 <td>1</td>
2451 </tr>
2452 <tr>
2453 <td>1</td>
2454 <td>1</td>
2455 <td>0</td>
2456 </tr>
2457 </tbody>
2458</table>
2459</div>
2460<p> </p>
2461<h5>Example:</h5>
2462<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2463 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2464 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2465 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
2466</pre>
2467</div>
2468
2469<!-- ======================================================================= -->
2470<div class="doc_subsection">
2471 <a name="vectorops">Vector Operations</a>
2472</div>
2473
2474<div class="doc_text">
2475
2476<p>LLVM supports several instructions to represent vector operations in a
2477target-independent manner. These instructions cover the element-access and
2478vector-specific operations needed to process vectors effectively. While LLVM
2479does directly support these vector operations, many sophisticated algorithms
2480will want to use target-specific intrinsics to take full advantage of a specific
2481target.</p>
2482
2483</div>
2484
2485<!-- _______________________________________________________________________ -->
2486<div class="doc_subsubsection">
2487 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2488</div>
2489
2490<div class="doc_text">
2491
2492<h5>Syntax:</h5>
2493
2494<pre>
2495 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2496</pre>
2497
2498<h5>Overview:</h5>
2499
2500<p>
2501The '<tt>extractelement</tt>' instruction extracts a single scalar
2502element from a vector at a specified index.
2503</p>
2504
2505
2506<h5>Arguments:</h5>
2507
2508<p>
2509The first operand of an '<tt>extractelement</tt>' instruction is a
2510value of <a href="#t_vector">vector</a> type. The second operand is
2511an index indicating the position from which to extract the element.
2512The index may be a variable.</p>
2513
2514<h5>Semantics:</h5>
2515
2516<p>
2517The result is a scalar of the same type as the element type of
2518<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2519<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2520results are undefined.
2521</p>
2522
2523<h5>Example:</h5>
2524
2525<pre>
2526 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
2527</pre>
2528</div>
2529
2530
2531<!-- _______________________________________________________________________ -->
2532<div class="doc_subsubsection">
2533 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2534</div>
2535
2536<div class="doc_text">
2537
2538<h5>Syntax:</h5>
2539
2540<pre>
2541 &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>
2542</pre>
2543
2544<h5>Overview:</h5>
2545
2546<p>
2547The '<tt>insertelement</tt>' instruction inserts a scalar
2548element into a vector at a specified index.
2549</p>
2550
2551
2552<h5>Arguments:</h5>
2553
2554<p>
2555The first operand of an '<tt>insertelement</tt>' instruction is a
2556value of <a href="#t_vector">vector</a> type. The second operand is a
2557scalar value whose type must equal the element type of the first
2558operand. The third operand is an index indicating the position at
2559which to insert the value. The index may be a variable.</p>
2560
2561<h5>Semantics:</h5>
2562
2563<p>
2564The result is a vector of the same type as <tt>val</tt>. Its
2565element values are those of <tt>val</tt> except at position
2566<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2567exceeds the length of <tt>val</tt>, the results are undefined.
2568</p>
2569
2570<h5>Example:</h5>
2571
2572<pre>
2573 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
2574</pre>
2575</div>
2576
2577<!-- _______________________________________________________________________ -->
2578<div class="doc_subsubsection">
2579 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2580</div>
2581
2582<div class="doc_text">
2583
2584<h5>Syntax:</h5>
2585
2586<pre>
2587 &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>
2588</pre>
2589
2590<h5>Overview:</h5>
2591
2592<p>
2593The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2594from two input vectors, returning a vector of the same type.
2595</p>
2596
2597<h5>Arguments:</h5>
2598
2599<p>
2600The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2601with types that match each other and types that match the result of the
2602instruction. The third argument is a shuffle mask, which has the same number
2603of elements as the other vector type, but whose element type is always 'i32'.
2604</p>
2605
2606<p>
2607The shuffle mask operand is required to be a constant vector with either
2608constant integer or undef values.
2609</p>
2610
2611<h5>Semantics:</h5>
2612
2613<p>
2614The elements of the two input vectors are numbered from left to right across
2615both of the vectors. The shuffle mask operand specifies, for each element of
2616the result vector, which element of the two input registers the result element
2617gets. The element selector may be undef (meaning "don't care") and the second
2618operand may be undef if performing a shuffle from only one vector.
2619</p>
2620
2621<h5>Example:</h5>
2622
2623<pre>
2624 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2625 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2626 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2627 &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.
2628</pre>
2629</div>
2630
2631
2632<!-- ======================================================================= -->
2633<div class="doc_subsection">
2634 <a name="memoryops">Memory Access and Addressing Operations</a>
2635</div>
2636
2637<div class="doc_text">
2638
2639<p>A key design point of an SSA-based representation is how it
2640represents memory. In LLVM, no memory locations are in SSA form, which
2641makes things very simple. This section describes how to read, write,
2642allocate, and free memory in LLVM.</p>
2643
2644</div>
2645
2646<!-- _______________________________________________________________________ -->
2647<div class="doc_subsubsection">
2648 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2649</div>
2650
2651<div class="doc_text">
2652
2653<h5>Syntax:</h5>
2654
2655<pre>
2656 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2657</pre>
2658
2659<h5>Overview:</h5>
2660
2661<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2662heap and returns a pointer to it.</p>
2663
2664<h5>Arguments:</h5>
2665
2666<p>The '<tt>malloc</tt>' instruction allocates
2667<tt>sizeof(&lt;type&gt;)*NumElements</tt>
2668bytes of memory from the operating system and returns a pointer of the
2669appropriate type to the program. If "NumElements" is specified, it is the
2670number of elements allocated. If an alignment is specified, the value result
2671of the allocation is guaranteed to be aligned to at least that boundary. If
2672not specified, or if zero, the target can choose to align the allocation on any
2673convenient boundary.</p>
2674
2675<p>'<tt>type</tt>' must be a sized type.</p>
2676
2677<h5>Semantics:</h5>
2678
2679<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2680a pointer is returned.</p>
2681
2682<h5>Example:</h5>
2683
2684<pre>
2685 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
2686
2687 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2688 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2689 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2690 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2691 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
2692</pre>
2693</div>
2694
2695<!-- _______________________________________________________________________ -->
2696<div class="doc_subsubsection">
2697 <a name="i_free">'<tt>free</tt>' Instruction</a>
2698</div>
2699
2700<div class="doc_text">
2701
2702<h5>Syntax:</h5>
2703
2704<pre>
2705 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
2706</pre>
2707
2708<h5>Overview:</h5>
2709
2710<p>The '<tt>free</tt>' instruction returns memory back to the unused
2711memory heap to be reallocated in the future.</p>
2712
2713<h5>Arguments:</h5>
2714
2715<p>'<tt>value</tt>' shall be a pointer value that points to a value
2716that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2717instruction.</p>
2718
2719<h5>Semantics:</h5>
2720
2721<p>Access to the memory pointed to by the pointer is no longer defined
2722after this instruction executes.</p>
2723
2724<h5>Example:</h5>
2725
2726<pre>
2727 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2728 free [4 x i8]* %array
2729</pre>
2730</div>
2731
2732<!-- _______________________________________________________________________ -->
2733<div class="doc_subsubsection">
2734 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2735</div>
2736
2737<div class="doc_text">
2738
2739<h5>Syntax:</h5>
2740
2741<pre>
2742 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2743</pre>
2744
2745<h5>Overview:</h5>
2746
2747<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
2748currently executing function, to be automatically released when this function
2749returns to its caller.</p>
2750
2751<h5>Arguments:</h5>
2752
2753<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
2754bytes of memory on the runtime stack, returning a pointer of the
2755appropriate type to the program. If "NumElements" is specified, it is the
2756number of elements allocated. If an alignment is specified, the value result
2757of the allocation is guaranteed to be aligned to at least that boundary. If
2758not specified, or if zero, the target can choose to align the allocation on any
2759convenient boundary.</p>
2760
2761<p>'<tt>type</tt>' may be any sized type.</p>
2762
2763<h5>Semantics:</h5>
2764
2765<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
2766memory is automatically released when the function returns. The '<tt>alloca</tt>'
2767instruction is commonly used to represent automatic variables that must
2768have an address available. When the function returns (either with the <tt><a
2769 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
2770instructions), the memory is reclaimed.</p>
2771
2772<h5>Example:</h5>
2773
2774<pre>
2775 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2776 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2777 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2778 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
2779</pre>
2780</div>
2781
2782<!-- _______________________________________________________________________ -->
2783<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2784Instruction</a> </div>
2785<div class="doc_text">
2786<h5>Syntax:</h5>
2787<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>
2788<h5>Overview:</h5>
2789<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
2790<h5>Arguments:</h5>
2791<p>The argument to the '<tt>load</tt>' instruction specifies the memory
2792address from which to load. The pointer must point to a <a
2793 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
2794marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
2795the number or order of execution of this <tt>load</tt> with other
2796volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2797instructions. </p>
2798<h5>Semantics:</h5>
2799<p>The location of memory pointed to is loaded.</p>
2800<h5>Examples:</h5>
2801<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
2802 <a
2803 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2804 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
2805</pre>
2806</div>
2807<!-- _______________________________________________________________________ -->
2808<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2809Instruction</a> </div>
2810<div class="doc_text">
2811<h5>Syntax:</h5>
2812<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2813 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2814</pre>
2815<h5>Overview:</h5>
2816<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
2817<h5>Arguments:</h5>
2818<p>There are two arguments to the '<tt>store</tt>' instruction: a value
2819to store and an address at which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
2820operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
2821operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
2822optimizer is not allowed to modify the number or order of execution of
2823this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2824 href="#i_store">store</a></tt> instructions.</p>
2825<h5>Semantics:</h5>
2826<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2827at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
2828<h5>Example:</h5>
2829<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Bill Wendling63ffa142007-10-22 05:10:05 +0000[diff] [blame]2830 store i32 3, i32* %ptr <i>; yields {void}</i>
2831 %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]2832</pre>
2833</div>
2834
2835<!-- _______________________________________________________________________ -->
2836<div class="doc_subsubsection">
2837 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2838</div>
2839
2840<div class="doc_text">
2841<h5>Syntax:</h5>
2842<pre>
2843 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2844</pre>
2845
2846<h5>Overview:</h5>
2847
2848<p>
2849The '<tt>getelementptr</tt>' instruction is used to get the address of a
2850subelement of an aggregate data structure.</p>
2851
2852<h5>Arguments:</h5>
2853
2854<p>This instruction takes a list of integer operands that indicate what
2855elements of the aggregate object to index to. The actual types of the arguments
2856provided depend on the type of the first pointer argument. The
2857'<tt>getelementptr</tt>' instruction is used to index down through the type
2858levels of a structure or to a specific index in an array. When indexing into a
2859structure, only <tt>i32</tt> integer constants are allowed. When indexing
2860into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2861be sign extended to 64-bit values.</p>
2862
2863<p>For example, let's consider a C code fragment and how it gets
2864compiled to LLVM:</p>
2865
2866<div class="doc_code">
2867<pre>
2868struct RT {
2869 char A;
2870 int B[10][20];
2871 char C;
2872};
2873struct ST {
2874 int X;
2875 double Y;
2876 struct RT Z;
2877};
2878
2879int *foo(struct ST *s) {
2880 return &amp;s[1].Z.B[5][13];
2881}
2882</pre>
2883</div>
2884
2885<p>The LLVM code generated by the GCC frontend is:</p>
2886
2887<div class="doc_code">
2888<pre>
2889%RT = type { i8 , [10 x [20 x i32]], i8 }
2890%ST = type { i32, double, %RT }
2891
2892define i32* %foo(%ST* %s) {
2893entry:
2894 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2895 ret i32* %reg
2896}
2897</pre>
2898</div>
2899
2900<h5>Semantics:</h5>
2901
2902<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
2903on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
2904and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
2905<a href="#t_integer">integer</a> type but the value will always be sign extended
2906to 64-bits. <a href="#t_struct">Structure</a> types require <tt>i32</tt>
2907<b>constants</b>.</p>
2908
2909<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
2910type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
2911}</tt>' type, a structure. The second index indexes into the third element of
2912the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2913i8 }</tt>' type, another structure. The third index indexes into the second
2914element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
2915array. The two dimensions of the array are subscripted into, yielding an
2916'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2917to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
2918
2919<p>Note that it is perfectly legal to index partially through a
2920structure, returning a pointer to an inner element. Because of this,
2921the LLVM code for the given testcase is equivalent to:</p>
2922
2923<pre>
2924 define i32* %foo(%ST* %s) {
2925 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2926 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2927 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2928 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2929 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2930 ret i32* %t5
2931 }
2932</pre>
2933
2934<p>Note that it is undefined to access an array out of bounds: array and
2935pointer indexes must always be within the defined bounds of the array type.
2936The one exception for this rules is zero length arrays. These arrays are
2937defined to be accessible as variable length arrays, which requires access
2938beyond the zero'th element.</p>
2939
2940<p>The getelementptr instruction is often confusing. For some more insight
2941into how it works, see <a href="GetElementPtr.html">the getelementptr
2942FAQ</a>.</p>
2943
2944<h5>Example:</h5>
2945
2946<pre>
2947 <i>; yields [12 x i8]*:aptr</i>
2948 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
2949</pre>
2950</div>
2951
2952<!-- ======================================================================= -->
2953<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
2954</div>
2955<div class="doc_text">
2956<p>The instructions in this category are the conversion instructions (casting)
2957which all take a single operand and a type. They perform various bit conversions
2958on the operand.</p>
2959</div>
2960
2961<!-- _______________________________________________________________________ -->
2962<div class="doc_subsubsection">
2963 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2964</div>
2965<div class="doc_text">
2966
2967<h5>Syntax:</h5>
2968<pre>
2969 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2970</pre>
2971
2972<h5>Overview:</h5>
2973<p>
2974The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2975</p>
2976
2977<h5>Arguments:</h5>
2978<p>
2979The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2980be an <a href="#t_integer">integer</a> type, and a type that specifies the size
2981and type of the result, which must be an <a href="#t_integer">integer</a>
2982type. The bit size of <tt>value</tt> must be larger than the bit size of
2983<tt>ty2</tt>. Equal sized types are not allowed.</p>
2984
2985<h5>Semantics:</h5>
2986<p>
2987The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
2988and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2989larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2990It will always truncate bits.</p>
2991
2992<h5>Example:</h5>
2993<pre>
2994 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
2995 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2996 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
2997</pre>
2998</div>
2999
3000<!-- _______________________________________________________________________ -->
3001<div class="doc_subsubsection">
3002 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3003</div>
3004<div class="doc_text">
3005
3006<h5>Syntax:</h5>
3007<pre>
3008 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3009</pre>
3010
3011<h5>Overview:</h5>
3012<p>The '<tt>zext</tt>' instruction zero extends its operand to type
3013<tt>ty2</tt>.</p>
3014
3015
3016<h5>Arguments:</h5>
3017<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3018<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3019also be of <a href="#t_integer">integer</a> type. The bit size of the
3020<tt>value</tt> must be smaller than the bit size of the destination type,
3021<tt>ty2</tt>.</p>
3022
3023<h5>Semantics:</h5>
3024<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3025bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3026
3027<p>When zero extending from i1, the result will always be either 0 or 1.</p>
3028
3029<h5>Example:</h5>
3030<pre>
3031 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3032 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3033</pre>
3034</div>
3035
3036<!-- _______________________________________________________________________ -->
3037<div class="doc_subsubsection">
3038 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3039</div>
3040<div class="doc_text">
3041
3042<h5>Syntax:</h5>
3043<pre>
3044 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3045</pre>
3046
3047<h5>Overview:</h5>
3048<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3049
3050<h5>Arguments:</h5>
3051<p>
3052The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3053<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3054also be of <a href="#t_integer">integer</a> type. The bit size of the
3055<tt>value</tt> must be smaller than the bit size of the destination type,
3056<tt>ty2</tt>.</p>
3057
3058<h5>Semantics:</h5>
3059<p>
3060The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3061bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3062the type <tt>ty2</tt>.</p>
3063
3064<p>When sign extending from i1, the extension always results in -1 or 0.</p>
3065
3066<h5>Example:</h5>
3067<pre>
3068 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3069 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3070</pre>
3071</div>
3072
3073<!-- _______________________________________________________________________ -->
3074<div class="doc_subsubsection">
3075 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3076</div>
3077
3078<div class="doc_text">
3079
3080<h5>Syntax:</h5>
3081
3082<pre>
3083 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3084</pre>
3085
3086<h5>Overview:</h5>
3087<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
3088<tt>ty2</tt>.</p>
3089
3090
3091<h5>Arguments:</h5>
3092<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
3093 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
3094cast it to. The size of <tt>value</tt> must be larger than the size of
3095<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
3096<i>no-op cast</i>.</p>
3097
3098<h5>Semantics:</h5>
3099<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
3100<a href="#t_floating">floating point</a> type to a smaller
3101<a href="#t_floating">floating point</a> type. If the value cannot fit within
3102the destination type, <tt>ty2</tt>, then the results are undefined.</p>
3103
3104<h5>Example:</h5>
3105<pre>
3106 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
3107 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
3108</pre>
3109</div>
3110
3111<!-- _______________________________________________________________________ -->
3112<div class="doc_subsubsection">
3113 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
3114</div>
3115<div class="doc_text">
3116
3117<h5>Syntax:</h5>
3118<pre>
3119 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3120</pre>
3121
3122<h5>Overview:</h5>
3123<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
3124floating point value.</p>
3125
3126<h5>Arguments:</h5>
3127<p>The '<tt>fpext</tt>' instruction takes a
3128<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
3129and a <a href="#t_floating">floating point</a> type to cast it to. The source
3130type must be smaller than the destination type.</p>
3131
3132<h5>Semantics:</h5>
3133<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
3134<a href="#t_floating">floating point</a> type to a larger
3135<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
3136used to make a <i>no-op cast</i> because it always changes bits. Use
3137<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
3138
3139<h5>Example:</h5>
3140<pre>
3141 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
3142 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
3143</pre>
3144</div>
3145
3146<!-- _______________________________________________________________________ -->
3147<div class="doc_subsubsection">
3148 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
3149</div>
3150<div class="doc_text">
3151
3152<h5>Syntax:</h5>
3153<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3154 &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]3155</pre>
3156
3157<h5>Overview:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3158<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3159unsigned integer equivalent of type <tt>ty2</tt>.
3160</p>
3161
3162<h5>Arguments:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3163<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]3164scalar or vector <a href="#t_floating">floating point</a> value, and a type
3165to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3166type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3167vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3168
3169<h5>Semantics:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3170<p> The '<tt>fptoui</tt>' instruction converts its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3171<a href="#t_floating">floating point</a> operand into the nearest (rounding
3172towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3173the results are undefined.</p>
3174
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3175<h5>Example:</h5>
3176<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3177 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3178 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3179 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3180</pre>
3181</div>
3182
3183<!-- _______________________________________________________________________ -->
3184<div class="doc_subsubsection">
3185 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
3186</div>
3187<div class="doc_text">
3188
3189<h5>Syntax:</h5>
3190<pre>
3191 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3192</pre>
3193
3194<h5>Overview:</h5>
3195<p>The '<tt>fptosi</tt>' instruction converts
3196<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
3197</p>
3198
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3199<h5>Arguments:</h5>
3200<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]3201scalar or vector <a href="#t_floating">floating point</a> value, and a type
3202to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3203type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3204vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3205
3206<h5>Semantics:</h5>
3207<p>The '<tt>fptosi</tt>' instruction converts its
3208<a href="#t_floating">floating point</a> operand into the nearest (rounding
3209towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3210the results are undefined.</p>
3211
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3212<h5>Example:</h5>
3213<pre>
3214 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3215 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3216 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
3217</pre>
3218</div>
3219
3220<!-- _______________________________________________________________________ -->
3221<div class="doc_subsubsection">
3222 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
3223</div>
3224<div class="doc_text">
3225
3226<h5>Syntax:</h5>
3227<pre>
3228 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3229</pre>
3230
3231<h5>Overview:</h5>
3232<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
3233integer and converts that value to the <tt>ty2</tt> type.</p>
3234
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3235<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3236<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
3237scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3238to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3239type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3240floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3241
3242<h5>Semantics:</h5>
3243<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
3244integer quantity and converts it to the corresponding floating point value. If
3245the value cannot fit in the floating point value, the results are undefined.</p>
3246
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3247<h5>Example:</h5>
3248<pre>
3249 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3250 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
3251</pre>
3252</div>
3253
3254<!-- _______________________________________________________________________ -->
3255<div class="doc_subsubsection">
3256 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
3257</div>
3258<div class="doc_text">
3259
3260<h5>Syntax:</h5>
3261<pre>
3262 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3263</pre>
3264
3265<h5>Overview:</h5>
3266<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
3267integer and converts that value to the <tt>ty2</tt> type.</p>
3268
3269<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3270<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
3271scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3272to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3273type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3274floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3275
3276<h5>Semantics:</h5>
3277<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
3278integer quantity and converts it to the corresponding floating point value. If
3279the value cannot fit in the floating point value, the results are undefined.</p>
3280
3281<h5>Example:</h5>
3282<pre>
3283 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3284 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
3285</pre>
3286</div>
3287
3288<!-- _______________________________________________________________________ -->
3289<div class="doc_subsubsection">
3290 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3291</div>
3292<div class="doc_text">
3293
3294<h5>Syntax:</h5>
3295<pre>
3296 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3297</pre>
3298
3299<h5>Overview:</h5>
3300<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3301the integer type <tt>ty2</tt>.</p>
3302
3303<h5>Arguments:</h5>
3304<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3305must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
3306<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3307
3308<h5>Semantics:</h5>
3309<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3310<tt>ty2</tt> by interpreting the pointer value as an integer and either
3311truncating or zero extending that value to the size of the integer type. If
3312<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3313<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3314are the same size, then nothing is done (<i>no-op cast</i>) other than a type
3315change.</p>
3316
3317<h5>Example:</h5>
3318<pre>
3319 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
3320 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
3321</pre>
3322</div>
3323
3324<!-- _______________________________________________________________________ -->
3325<div class="doc_subsubsection">
3326 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3327</div>
3328<div class="doc_text">
3329
3330<h5>Syntax:</h5>
3331<pre>
3332 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3333</pre>
3334
3335<h5>Overview:</h5>
3336<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3337a pointer type, <tt>ty2</tt>.</p>
3338
3339<h5>Arguments:</h5>
3340<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
3341value to cast, and a type to cast it to, which must be a
3342<a href="#t_pointer">pointer</a> type.
3343
3344<h5>Semantics:</h5>
3345<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3346<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3347the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3348size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3349the size of a pointer then a zero extension is done. If they are the same size,
3350nothing is done (<i>no-op cast</i>).</p>
3351
3352<h5>Example:</h5>
3353<pre>
3354 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
3355 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
3356 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
3357</pre>
3358</div>
3359
3360<!-- _______________________________________________________________________ -->
3361<div class="doc_subsubsection">
3362 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
3363</div>
3364<div class="doc_text">
3365
3366<h5>Syntax:</h5>
3367<pre>
3368 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3369</pre>
3370
3371<h5>Overview:</h5>
3372<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3373<tt>ty2</tt> without changing any bits.</p>
3374
3375<h5>Arguments:</h5>
3376<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
3377a first class value, and a type to cast it to, which must also be a <a
3378 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
3379and the destination type, <tt>ty2</tt>, must be identical. If the source
3380type is a pointer, the destination type must also be a pointer.</p>
3381
3382<h5>Semantics:</h5>
3383<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3384<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3385this conversion. The conversion is done as if the <tt>value</tt> had been
3386stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3387converted to other pointer types with this instruction. To convert pointers to
3388other types, use the <a href="#i_inttoptr">inttoptr</a> or
3389<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
3390
3391<h5>Example:</h5>
3392<pre>
3393 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3394 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3395 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
3396</pre>
3397</div>
3398
3399<!-- ======================================================================= -->
3400<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3401<div class="doc_text">
3402<p>The instructions in this category are the "miscellaneous"
3403instructions, which defy better classification.</p>
3404</div>
3405
3406<!-- _______________________________________________________________________ -->
3407<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3408</div>
3409<div class="doc_text">
3410<h5>Syntax:</h5>
3411<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3412</pre>
3413<h5>Overview:</h5>
3414<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3415of its two integer operands.</p>
3416<h5>Arguments:</h5>
3417<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3418the condition code indicating the kind of comparison to perform. It is not
3419a value, just a keyword. The possible condition code are:
3420<ol>
3421 <li><tt>eq</tt>: equal</li>
3422 <li><tt>ne</tt>: not equal </li>
3423 <li><tt>ugt</tt>: unsigned greater than</li>
3424 <li><tt>uge</tt>: unsigned greater or equal</li>
3425 <li><tt>ult</tt>: unsigned less than</li>
3426 <li><tt>ule</tt>: unsigned less or equal</li>
3427 <li><tt>sgt</tt>: signed greater than</li>
3428 <li><tt>sge</tt>: signed greater or equal</li>
3429 <li><tt>slt</tt>: signed less than</li>
3430 <li><tt>sle</tt>: signed less or equal</li>
3431</ol>
3432<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
3433<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
3434<h5>Semantics:</h5>
3435<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3436the condition code given as <tt>cond</tt>. The comparison performed always
3437yields a <a href="#t_primitive">i1</a> result, as follows:
3438<ol>
3439 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3440 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3441 </li>
3442 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3443 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3444 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3445 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3446 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3447 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3448 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3449 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3450 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3451 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3452 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3453 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3454 <li><tt>sge</tt>: interprets the operands as signed values and yields
3455 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3456 <li><tt>slt</tt>: interprets the operands as signed values and yields
3457 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3458 <li><tt>sle</tt>: interprets the operands as signed values and yields
3459 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3460</ol>
3461<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3462values are compared as if they were integers.</p>
3463
3464<h5>Example:</h5>
3465<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3466 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3467 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3468 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3469 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3470 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
3471</pre>
3472</div>
3473
3474<!-- _______________________________________________________________________ -->
3475<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3476</div>
3477<div class="doc_text">
3478<h5>Syntax:</h5>
3479<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3480</pre>
3481<h5>Overview:</h5>
3482<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3483of its floating point operands.</p>
3484<h5>Arguments:</h5>
3485<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3486the condition code indicating the kind of comparison to perform. It is not
3487a value, just a keyword. The possible condition code are:
3488<ol>
3489 <li><tt>false</tt>: no comparison, always returns false</li>
3490 <li><tt>oeq</tt>: ordered and equal</li>
3491 <li><tt>ogt</tt>: ordered and greater than </li>
3492 <li><tt>oge</tt>: ordered and greater than or equal</li>
3493 <li><tt>olt</tt>: ordered and less than </li>
3494 <li><tt>ole</tt>: ordered and less than or equal</li>
3495 <li><tt>one</tt>: ordered and not equal</li>
3496 <li><tt>ord</tt>: ordered (no nans)</li>
3497 <li><tt>ueq</tt>: unordered or equal</li>
3498 <li><tt>ugt</tt>: unordered or greater than </li>
3499 <li><tt>uge</tt>: unordered or greater than or equal</li>
3500 <li><tt>ult</tt>: unordered or less than </li>
3501 <li><tt>ule</tt>: unordered or less than or equal</li>
3502 <li><tt>une</tt>: unordered or not equal</li>
3503 <li><tt>uno</tt>: unordered (either nans)</li>
3504 <li><tt>true</tt>: no comparison, always returns true</li>
3505</ol>
3506<p><i>Ordered</i> means that neither operand is a QNAN while
3507<i>unordered</i> means that either operand may be a QNAN.</p>
3508<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3509<a href="#t_floating">floating point</a> typed. They must have identical
3510types.</p>
3511<h5>Semantics:</h5>
3512<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3513the condition code given as <tt>cond</tt>. The comparison performed always
3514yields a <a href="#t_primitive">i1</a> result, as follows:
3515<ol>
3516 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
3517 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3518 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3519 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3520 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
3521 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3522 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3523 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3524 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3525 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3526 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3527 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3528 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3529 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3530 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
3531 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3532 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
3533 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3534 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
3535 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3536 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
3537 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3538 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
3539 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3540 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
3541 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3542 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
3543 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3544</ol>
3545
3546<h5>Example:</h5>
3547<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3548 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3549 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3550 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3551</pre>
3552</div>
3553
3554<!-- _______________________________________________________________________ -->
3555<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3556Instruction</a> </div>
3557<div class="doc_text">
3558<h5>Syntax:</h5>
3559<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3560<h5>Overview:</h5>
3561<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3562the SSA graph representing the function.</p>
3563<h5>Arguments:</h5>
3564<p>The type of the incoming values is specified with the first type
3565field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3566as arguments, with one pair for each predecessor basic block of the
3567current block. Only values of <a href="#t_firstclass">first class</a>
3568type may be used as the value arguments to the PHI node. Only labels
3569may be used as the label arguments.</p>
3570<p>There must be no non-phi instructions between the start of a basic
3571block and the PHI instructions: i.e. PHI instructions must be first in
3572a basic block.</p>
3573<h5>Semantics:</h5>
3574<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
3575specified by the pair corresponding to the predecessor basic block that executed
3576just prior to the current block.</p>
3577<h5>Example:</h5>
3578<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>
3579</div>
3580
3581<!-- _______________________________________________________________________ -->
3582<div class="doc_subsubsection">
3583 <a name="i_select">'<tt>select</tt>' Instruction</a>
3584</div>
3585
3586<div class="doc_text">
3587
3588<h5>Syntax:</h5>
3589
3590<pre>
3591 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
3592</pre>
3593
3594<h5>Overview:</h5>
3595
3596<p>
3597The '<tt>select</tt>' instruction is used to choose one value based on a
3598condition, without branching.
3599</p>
3600
3601
3602<h5>Arguments:</h5>
3603
3604<p>
3605The '<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.
3606</p>
3607
3608<h5>Semantics:</h5>
3609
3610<p>
3611If the boolean condition evaluates to true, the instruction returns the first
3612value argument; otherwise, it returns the second value argument.
3613</p>
3614
3615<h5>Example:</h5>
3616
3617<pre>
3618 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
3619</pre>
3620</div>
3621
3622
3623<!-- _______________________________________________________________________ -->
3624<div class="doc_subsubsection">
3625 <a name="i_call">'<tt>call</tt>' Instruction</a>
3626</div>
3627
3628<div class="doc_text">
3629
3630<h5>Syntax:</h5>
3631<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3632 &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]3633</pre>
3634
3635<h5>Overview:</h5>
3636
3637<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
3638
3639<h5>Arguments:</h5>
3640
3641<p>This instruction requires several arguments:</p>
3642
3643<ol>
3644 <li>
3645 <p>The optional "tail" marker indicates whether the callee function accesses
3646 any allocas or varargs in the caller. If the "tail" marker is present, the
3647 function call is eligible for tail call optimization. Note that calls may
3648 be marked "tail" even if they do not occur before a <a
3649 href="#i_ret"><tt>ret</tt></a> instruction.
3650 </li>
3651 <li>
3652 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
3653 convention</a> the call should use. If none is specified, the call defaults
3654 to using C calling conventions.
3655 </li>
3656 <li>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3657 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
3658 the type of the return value. Functions that return no value are marked
3659 <tt><a href="#t_void">void</a></tt>.</p>
3660 </li>
3661 <li>
3662 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
3663 value being invoked. The argument types must match the types implied by
3664 this signature. This type can be omitted if the function is not varargs
3665 and if the function type does not return a pointer to a function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3666 </li>
3667 <li>
3668 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3669 be invoked. In most cases, this is a direct function invocation, but
3670 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
3671 to function value.</p>
3672 </li>
3673 <li>
3674 <p>'<tt>function args</tt>': argument list whose types match the
3675 function signature argument types. All arguments must be of
3676 <a href="#t_firstclass">first class</a> type. If the function signature
3677 indicates the function accepts a variable number of arguments, the extra
3678 arguments can be specified.</p>
3679 </li>
3680</ol>
3681
3682<h5>Semantics:</h5>
3683
3684<p>The '<tt>call</tt>' instruction is used to cause control flow to
3685transfer to a specified function, with its incoming arguments bound to
3686the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3687instruction in the called function, control flow continues with the
3688instruction after the function call, and the return value of the
3689function is bound to the result argument. This is a simpler case of
3690the <a href="#i_invoke">invoke</a> instruction.</p>
3691
3692<h5>Example:</h5>
3693
3694<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3695 %retval = call i32 @test(i32 %argc)
3696 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42);
3697 %X = tail call i32 @foo()
3698 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo()
3699 %Z = call void %foo(i8 97 signext)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3700</pre>
3701
3702</div>
3703
3704<!-- _______________________________________________________________________ -->
3705<div class="doc_subsubsection">
3706 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
3707</div>
3708
3709<div class="doc_text">
3710
3711<h5>Syntax:</h5>
3712
3713<pre>
3714 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
3715</pre>
3716
3717<h5>Overview:</h5>
3718
3719<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
3720the "variable argument" area of a function call. It is used to implement the
3721<tt>va_arg</tt> macro in C.</p>
3722
3723<h5>Arguments:</h5>
3724
3725<p>This instruction takes a <tt>va_list*</tt> value and the type of
3726the argument. It returns a value of the specified argument type and
3727increments the <tt>va_list</tt> to point to the next argument. The
3728actual type of <tt>va_list</tt> is target specific.</p>
3729
3730<h5>Semantics:</h5>
3731
3732<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3733type from the specified <tt>va_list</tt> and causes the
3734<tt>va_list</tt> to point to the next argument. For more information,
3735see the variable argument handling <a href="#int_varargs">Intrinsic
3736Functions</a>.</p>
3737
3738<p>It is legal for this instruction to be called in a function which does not
3739take a variable number of arguments, for example, the <tt>vfprintf</tt>
3740function.</p>
3741
3742<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
3743href="#intrinsics">intrinsic function</a> because it takes a type as an
3744argument.</p>
3745
3746<h5>Example:</h5>
3747
3748<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3749
3750</div>
3751
3752<!-- *********************************************************************** -->
3753<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3754<!-- *********************************************************************** -->
3755
3756<div class="doc_text">
3757
3758<p>LLVM supports the notion of an "intrinsic function". These functions have
3759well known names and semantics and are required to follow certain restrictions.
3760Overall, these intrinsics represent an extension mechanism for the LLVM
3761language that does not require changing all of the transformations in LLVM when
3762adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
3763
3764<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3765prefix is reserved in LLVM for intrinsic names; thus, function names may not
3766begin with this prefix. Intrinsic functions must always be external functions:
3767you cannot define the body of intrinsic functions. Intrinsic functions may
3768only be used in call or invoke instructions: it is illegal to take the address
3769of an intrinsic function. Additionally, because intrinsic functions are part
3770of the LLVM language, it is required if any are added that they be documented
3771here.</p>
3772
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3773<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
3774a family of functions that perform the same operation but on different data
3775types. Because LLVM can represent over 8 million different integer types,
3776overloading is used commonly to allow an intrinsic function to operate on any
3777integer type. One or more of the argument types or the result type can be
3778overloaded to accept any integer type. Argument types may also be defined as
3779exactly matching a previous argument's type or the result type. This allows an
3780intrinsic function which accepts multiple arguments, but needs all of them to
3781be of the same type, to only be overloaded with respect to a single argument or
3782the result.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3783
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3784<p>Overloaded intrinsics will have the names of its overloaded argument types
3785encoded into its function name, each preceded by a period. Only those types
3786which are overloaded result in a name suffix. Arguments whose type is matched
3787against another type do not. For example, the <tt>llvm.ctpop</tt> function can
3788take an integer of any width and returns an integer of exactly the same integer
3789width. This leads to a family of functions such as
3790<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
3791Only one type, the return type, is overloaded, and only one type suffix is
3792required. Because the argument's type is matched against the return type, it
3793does not require its own name suffix.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3794
3795<p>To learn how to add an intrinsic function, please see the
3796<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
3797</p>
3798
3799</div>
3800
3801<!-- ======================================================================= -->
3802<div class="doc_subsection">
3803 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3804</div>
3805
3806<div class="doc_text">
3807
3808<p>Variable argument support is defined in LLVM with the <a
3809 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
3810intrinsic functions. These functions are related to the similarly
3811named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
3812
3813<p>All of these functions operate on arguments that use a
3814target-specific value type "<tt>va_list</tt>". The LLVM assembly
3815language reference manual does not define what this type is, so all
3816transformations should be prepared to handle these functions regardless of
3817the type used.</p>
3818
3819<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
3820instruction and the variable argument handling intrinsic functions are
3821used.</p>
3822
3823<div class="doc_code">
3824<pre>
3825define i32 @test(i32 %X, ...) {
3826 ; Initialize variable argument processing
3827 %ap = alloca i8*
3828 %ap2 = bitcast i8** %ap to i8*
3829 call void @llvm.va_start(i8* %ap2)
3830
3831 ; Read a single integer argument
3832 %tmp = va_arg i8** %ap, i32
3833
3834 ; Demonstrate usage of llvm.va_copy and llvm.va_end
3835 %aq = alloca i8*
3836 %aq2 = bitcast i8** %aq to i8*
3837 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
3838 call void @llvm.va_end(i8* %aq2)
3839
3840 ; Stop processing of arguments.
3841 call void @llvm.va_end(i8* %ap2)
3842 ret i32 %tmp
3843}
3844
3845declare void @llvm.va_start(i8*)
3846declare void @llvm.va_copy(i8*, i8*)
3847declare void @llvm.va_end(i8*)
3848</pre>
3849</div>
3850
3851</div>
3852
3853<!-- _______________________________________________________________________ -->
3854<div class="doc_subsubsection">
3855 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3856</div>
3857
3858
3859<div class="doc_text">
3860<h5>Syntax:</h5>
3861<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
3862<h5>Overview:</h5>
3863<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3864<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3865href="#i_va_arg">va_arg</a></tt>.</p>
3866
3867<h5>Arguments:</h5>
3868
3869<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3870
3871<h5>Semantics:</h5>
3872
3873<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3874macro available in C. In a target-dependent way, it initializes the
3875<tt>va_list</tt> element to which the argument points, so that the next call to
3876<tt>va_arg</tt> will produce the first variable argument passed to the function.
3877Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3878last argument of the function as the compiler can figure that out.</p>
3879
3880</div>
3881
3882<!-- _______________________________________________________________________ -->
3883<div class="doc_subsubsection">
3884 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3885</div>
3886
3887<div class="doc_text">
3888<h5>Syntax:</h5>
3889<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
3890<h5>Overview:</h5>
3891
3892<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
3893which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
3894or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
3895
3896<h5>Arguments:</h5>
3897
3898<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
3899
3900<h5>Semantics:</h5>
3901
3902<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
3903macro available in C. In a target-dependent way, it destroys the
3904<tt>va_list</tt> element to which the argument points. Calls to <a
3905href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
3906<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
3907<tt>llvm.va_end</tt>.</p>
3908
3909</div>
3910
3911<!-- _______________________________________________________________________ -->
3912<div class="doc_subsubsection">
3913 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3914</div>
3915
3916<div class="doc_text">
3917
3918<h5>Syntax:</h5>
3919
3920<pre>
3921 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
3922</pre>
3923
3924<h5>Overview:</h5>
3925
3926<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
3927from the source argument list to the destination argument list.</p>
3928
3929<h5>Arguments:</h5>
3930
3931<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
3932The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
3933
3934
3935<h5>Semantics:</h5>
3936
3937<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
3938macro available in C. In a target-dependent way, it copies the source
3939<tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
3940intrinsic is necessary because the <tt><a href="#int_va_start">
3941llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
3942example, memory allocation.</p>
3943
3944</div>
3945
3946<!-- ======================================================================= -->
3947<div class="doc_subsection">
3948 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3949</div>
3950
3951<div class="doc_text">
3952
3953<p>
3954LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3955Collection</a> requires the implementation and generation of these intrinsics.
3956These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
3957stack</a>, as well as garbage collector implementations that require <a
3958href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
3959Front-ends for type-safe garbage collected languages should generate these
3960intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3961href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3962</p>
3963</div>
3964
3965<!-- _______________________________________________________________________ -->
3966<div class="doc_subsubsection">
3967 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3968</div>
3969
3970<div class="doc_text">
3971
3972<h5>Syntax:</h5>
3973
3974<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]3975 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3976</pre>
3977
3978<h5>Overview:</h5>
3979
3980<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
3981the code generator, and allows some metadata to be associated with it.</p>
3982
3983<h5>Arguments:</h5>
3984
3985<p>The first argument specifies the address of a stack object that contains the
3986root pointer. The second pointer (which must be either a constant or a global
3987value address) contains the meta-data to be associated with the root.</p>
3988
3989<h5>Semantics:</h5>
3990
3991<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3992location. At compile-time, the code generator generates information to allow
3993the runtime to find the pointer at GC safe points.
3994</p>
3995
3996</div>
3997
3998
3999<!-- _______________________________________________________________________ -->
4000<div class="doc_subsubsection">
4001 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
4002</div>
4003
4004<div class="doc_text">
4005
4006<h5>Syntax:</h5>
4007
4008<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4009 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4010</pre>
4011
4012<h5>Overview:</h5>
4013
4014<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
4015locations, allowing garbage collector implementations that require read
4016barriers.</p>
4017
4018<h5>Arguments:</h5>
4019
4020<p>The second argument is the address to read from, which should be an address
4021allocated from the garbage collector. The first object is a pointer to the
4022start of the referenced object, if needed by the language runtime (otherwise
4023null).</p>
4024
4025<h5>Semantics:</h5>
4026
4027<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
4028instruction, but may be replaced with substantially more complex code by the
4029garbage collector runtime, as needed.</p>
4030
4031</div>
4032
4033
4034<!-- _______________________________________________________________________ -->
4035<div class="doc_subsubsection">
4036 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
4037</div>
4038
4039<div class="doc_text">
4040
4041<h5>Syntax:</h5>
4042
4043<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4044 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4045</pre>
4046
4047<h5>Overview:</h5>
4048
4049<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
4050locations, allowing garbage collector implementations that require write
4051barriers (such as generational or reference counting collectors).</p>
4052
4053<h5>Arguments:</h5>
4054
4055<p>The first argument is the reference to store, the second is the start of the
4056object to store it to, and the third is the address of the field of Obj to
4057store to. If the runtime does not require a pointer to the object, Obj may be
4058null.</p>
4059
4060<h5>Semantics:</h5>
4061
4062<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
4063instruction, but may be replaced with substantially more complex code by the
4064garbage collector runtime, as needed.</p>
4065
4066</div>
4067
4068
4069
4070<!-- ======================================================================= -->
4071<div class="doc_subsection">
4072 <a name="int_codegen">Code Generator Intrinsics</a>
4073</div>
4074
4075<div class="doc_text">
4076<p>
4077These intrinsics are provided by LLVM to expose special features that may only
4078be implemented with code generator support.
4079</p>
4080
4081</div>
4082
4083<!-- _______________________________________________________________________ -->
4084<div class="doc_subsubsection">
4085 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
4086</div>
4087
4088<div class="doc_text">
4089
4090<h5>Syntax:</h5>
4091<pre>
4092 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
4093</pre>
4094
4095<h5>Overview:</h5>
4096
4097<p>
4098The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
4099target-specific value indicating the return address of the current function
4100or one of its callers.
4101</p>
4102
4103<h5>Arguments:</h5>
4104
4105<p>
4106The argument to this intrinsic indicates which function to return the address
4107for. Zero indicates the calling function, one indicates its caller, etc. The
4108argument is <b>required</b> to be a constant integer value.
4109</p>
4110
4111<h5>Semantics:</h5>
4112
4113<p>
4114The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
4115the return address of the specified call frame, or zero if it cannot be
4116identified. The value returned by this intrinsic is likely to be incorrect or 0
4117for arguments other than zero, so it should only be used for debugging purposes.
4118</p>
4119
4120<p>
4121Note that calling this intrinsic does not prevent function inlining or other
4122aggressive transformations, so the value returned may not be that of the obvious
4123source-language caller.
4124</p>
4125</div>
4126
4127
4128<!-- _______________________________________________________________________ -->
4129<div class="doc_subsubsection">
4130 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
4131</div>
4132
4133<div class="doc_text">
4134
4135<h5>Syntax:</h5>
4136<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4137 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4138</pre>
4139
4140<h5>Overview:</h5>
4141
4142<p>
4143The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
4144target-specific frame pointer value for the specified stack frame.
4145</p>
4146
4147<h5>Arguments:</h5>
4148
4149<p>
4150The argument to this intrinsic indicates which function to return the frame
4151pointer for. Zero indicates the calling function, one indicates its caller,
4152etc. The argument is <b>required</b> to be a constant integer value.
4153</p>
4154
4155<h5>Semantics:</h5>
4156
4157<p>
4158The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
4159the frame address of the specified call frame, or zero if it cannot be
4160identified. The value returned by this intrinsic is likely to be incorrect or 0
4161for arguments other than zero, so it should only be used for debugging purposes.
4162</p>
4163
4164<p>
4165Note that calling this intrinsic does not prevent function inlining or other
4166aggressive transformations, so the value returned may not be that of the obvious
4167source-language caller.
4168</p>
4169</div>
4170
4171<!-- _______________________________________________________________________ -->
4172<div class="doc_subsubsection">
4173 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
4174</div>
4175
4176<div class="doc_text">
4177
4178<h5>Syntax:</h5>
4179<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4180 declare i8 *@llvm.stacksave()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4181</pre>
4182
4183<h5>Overview:</h5>
4184
4185<p>
4186The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
4187the function stack, for use with <a href="#int_stackrestore">
4188<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4189features like scoped automatic variable sized arrays in C99.
4190</p>
4191
4192<h5>Semantics:</h5>
4193
4194<p>
4195This intrinsic returns a opaque pointer value that can be passed to <a
4196href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
4197<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4198<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4199state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4200practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4201that were allocated after the <tt>llvm.stacksave</tt> was executed.
4202</p>
4203
4204</div>
4205
4206<!-- _______________________________________________________________________ -->
4207<div class="doc_subsubsection">
4208 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
4209</div>
4210
4211<div class="doc_text">
4212
4213<h5>Syntax:</h5>
4214<pre>
4215 declare void @llvm.stackrestore(i8 * %ptr)
4216</pre>
4217
4218<h5>Overview:</h5>
4219
4220<p>
4221The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4222the function stack to the state it was in when the corresponding <a
4223href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
4224useful for implementing language features like scoped automatic variable sized
4225arrays in C99.
4226</p>
4227
4228<h5>Semantics:</h5>
4229
4230<p>
4231See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
4232</p>
4233
4234</div>
4235
4236
4237<!-- _______________________________________________________________________ -->
4238<div class="doc_subsubsection">
4239 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
4240</div>
4241
4242<div class="doc_text">
4243
4244<h5>Syntax:</h5>
4245<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4246 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]4247</pre>
4248
4249<h5>Overview:</h5>
4250
4251
4252<p>
4253The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
4254a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4255no
4256effect on the behavior of the program but can change its performance
4257characteristics.
4258</p>
4259
4260<h5>Arguments:</h5>
4261
4262<p>
4263<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4264determining if the fetch should be for a read (0) or write (1), and
4265<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
4266locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
4267<tt>locality</tt> arguments must be constant integers.
4268</p>
4269
4270<h5>Semantics:</h5>
4271
4272<p>
4273This intrinsic does not modify the behavior of the program. In particular,
4274prefetches cannot trap and do not produce a value. On targets that support this
4275intrinsic, the prefetch can provide hints to the processor cache for better
4276performance.
4277</p>
4278
4279</div>
4280
4281<!-- _______________________________________________________________________ -->
4282<div class="doc_subsubsection">
4283 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4284</div>
4285
4286<div class="doc_text">
4287
4288<h5>Syntax:</h5>
4289<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4290 declare void @llvm.pcmarker(i32 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4291</pre>
4292
4293<h5>Overview:</h5>
4294
4295
4296<p>
4297The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4298(PC) in a region of
4299code to simulators and other tools. The method is target specific, but it is
4300expected that the marker will use exported symbols to transmit the PC of the marker.
4301The marker makes no guarantees that it will remain with any specific instruction
4302after optimizations. It is possible that the presence of a marker will inhibit
4303optimizations. The intended use is to be inserted after optimizations to allow
4304correlations of simulation runs.
4305</p>
4306
4307<h5>Arguments:</h5>
4308
4309<p>
4310<tt>id</tt> is a numerical id identifying the marker.
4311</p>
4312
4313<h5>Semantics:</h5>
4314
4315<p>
4316This intrinsic does not modify the behavior of the program. Backends that do not
4317support this intrinisic may ignore it.
4318</p>
4319
4320</div>
4321
4322<!-- _______________________________________________________________________ -->
4323<div class="doc_subsubsection">
4324 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4325</div>
4326
4327<div class="doc_text">
4328
4329<h5>Syntax:</h5>
4330<pre>
4331 declare i64 @llvm.readcyclecounter( )
4332</pre>
4333
4334<h5>Overview:</h5>
4335
4336
4337<p>
4338The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4339counter register (or similar low latency, high accuracy clocks) on those targets
4340that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4341As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4342should only be used for small timings.
4343</p>
4344
4345<h5>Semantics:</h5>
4346
4347<p>
4348When directly supported, reading the cycle counter should not modify any memory.
4349Implementations are allowed to either return a application specific value or a
4350system wide value. On backends without support, this is lowered to a constant 0.
4351</p>
4352
4353</div>
4354
4355<!-- ======================================================================= -->
4356<div class="doc_subsection">
4357 <a name="int_libc">Standard C Library Intrinsics</a>
4358</div>
4359
4360<div class="doc_text">
4361<p>
4362LLVM provides intrinsics for a few important standard C library functions.
4363These intrinsics allow source-language front-ends to pass information about the
4364alignment of the pointer arguments to the code generator, providing opportunity
4365for more efficient code generation.
4366</p>
4367
4368</div>
4369
4370<!-- _______________________________________________________________________ -->
4371<div class="doc_subsubsection">
4372 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4373</div>
4374
4375<div class="doc_text">
4376
4377<h5>Syntax:</h5>
4378<pre>
4379 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4380 i32 &lt;len&gt;, i32 &lt;align&gt;)
4381 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4382 i64 &lt;len&gt;, i32 &lt;align&gt;)
4383</pre>
4384
4385<h5>Overview:</h5>
4386
4387<p>
4388The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4389location to the destination location.
4390</p>
4391
4392<p>
4393Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4394intrinsics do not return a value, and takes an extra alignment argument.
4395</p>
4396
4397<h5>Arguments:</h5>
4398
4399<p>
4400The first argument is a pointer to the destination, the second is a pointer to
4401the source. The third argument is an integer argument
4402specifying the number of bytes to copy, and the fourth argument is the alignment
4403of the source and destination locations.
4404</p>
4405
4406<p>
4407If the call to this intrinisic has an alignment value that is not 0 or 1, then
4408the caller guarantees that both the source and destination pointers are aligned
4409to that boundary.
4410</p>
4411
4412<h5>Semantics:</h5>
4413
4414<p>
4415The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4416location to the destination location, which are not allowed to overlap. It
4417copies "len" bytes of memory over. If the argument is known to be aligned to
4418some boundary, this can be specified as the fourth argument, otherwise it should
4419be set to 0 or 1.
4420</p>
4421</div>
4422
4423
4424<!-- _______________________________________________________________________ -->
4425<div class="doc_subsubsection">
4426 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4427</div>
4428
4429<div class="doc_text">
4430
4431<h5>Syntax:</h5>
4432<pre>
4433 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4434 i32 &lt;len&gt;, i32 &lt;align&gt;)
4435 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4436 i64 &lt;len&gt;, i32 &lt;align&gt;)
4437</pre>
4438
4439<h5>Overview:</h5>
4440
4441<p>
4442The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4443location to the destination location. It is similar to the
4444'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
4445</p>
4446
4447<p>
4448Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4449intrinsics do not return a value, and takes an extra alignment argument.
4450</p>
4451
4452<h5>Arguments:</h5>
4453
4454<p>
4455The first argument is a pointer to the destination, the second is a pointer to
4456the source. The third argument is an integer argument
4457specifying the number of bytes to copy, and the fourth argument is the alignment
4458of the source and destination locations.
4459</p>
4460
4461<p>
4462If the call to this intrinisic has an alignment value that is not 0 or 1, then
4463the caller guarantees that the source and destination pointers are aligned to
4464that boundary.
4465</p>
4466
4467<h5>Semantics:</h5>
4468
4469<p>
4470The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
4471location to the destination location, which may overlap. It
4472copies "len" bytes of memory over. If the argument is known to be aligned to
4473some boundary, this can be specified as the fourth argument, otherwise it should
4474be set to 0 or 1.
4475</p>
4476</div>
4477
4478
4479<!-- _______________________________________________________________________ -->
4480<div class="doc_subsubsection">
4481 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
4482</div>
4483
4484<div class="doc_text">
4485
4486<h5>Syntax:</h5>
4487<pre>
4488 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4489 i32 &lt;len&gt;, i32 &lt;align&gt;)
4490 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4491 i64 &lt;len&gt;, i32 &lt;align&gt;)
4492</pre>
4493
4494<h5>Overview:</h5>
4495
4496<p>
4497The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
4498byte value.
4499</p>
4500
4501<p>
4502Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4503does not return a value, and takes an extra alignment argument.
4504</p>
4505
4506<h5>Arguments:</h5>
4507
4508<p>
4509The first argument is a pointer to the destination to fill, the second is the
4510byte value to fill it with, the third argument is an integer
4511argument specifying the number of bytes to fill, and the fourth argument is the
4512known alignment of destination location.
4513</p>
4514
4515<p>
4516If the call to this intrinisic has an alignment value that is not 0 or 1, then
4517the caller guarantees that the destination pointer is aligned to that boundary.
4518</p>
4519
4520<h5>Semantics:</h5>
4521
4522<p>
4523The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4524the
4525destination location. If the argument is known to be aligned to some boundary,
4526this can be specified as the fourth argument, otherwise it should be set to 0 or
45271.
4528</p>
4529</div>
4530
4531
4532<!-- _______________________________________________________________________ -->
4533<div class="doc_subsubsection">
4534 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
4535</div>
4536
4537<div class="doc_text">
4538
4539<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4540<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]4541floating point or vector of floating point type. Not all targets support all
4542types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4543<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4544 declare float @llvm.sqrt.f32(float %Val)
4545 declare double @llvm.sqrt.f64(double %Val)
4546 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
4547 declare fp128 @llvm.sqrt.f128(fp128 %Val)
4548 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4549</pre>
4550
4551<h5>Overview:</h5>
4552
4553<p>
4554The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4555returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4556<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4557negative numbers (which allows for better optimization).
4558</p>
4559
4560<h5>Arguments:</h5>
4561
4562<p>
4563The argument and return value are floating point numbers of the same type.
4564</p>
4565
4566<h5>Semantics:</h5>
4567
4568<p>
4569This function returns the sqrt of the specified operand if it is a nonnegative
4570floating point number.
4571</p>
4572</div>
4573
4574<!-- _______________________________________________________________________ -->
4575<div class="doc_subsubsection">
4576 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4577</div>
4578
4579<div class="doc_text">
4580
4581<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4582<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]4583floating point or vector of floating point type. Not all targets support all
4584types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4585<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4586 declare float @llvm.powi.f32(float %Val, i32 %power)
4587 declare double @llvm.powi.f64(double %Val, i32 %power)
4588 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
4589 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
4590 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4591</pre>
4592
4593<h5>Overview:</h5>
4594
4595<p>
4596The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4597specified (positive or negative) power. The order of evaluation of
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4598multiplications is not defined. When a vector of floating point type is
4599used, the second argument remains a scalar integer value.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4600</p>
4601
4602<h5>Arguments:</h5>
4603
4604<p>
4605The second argument is an integer power, and the first is a value to raise to
4606that power.
4607</p>
4608
4609<h5>Semantics:</h5>
4610
4611<p>
4612This function returns the first value raised to the second power with an
4613unspecified sequence of rounding operations.</p>
4614</div>
4615
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4616<!-- _______________________________________________________________________ -->
4617<div class="doc_subsubsection">
4618 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
4619</div>
4620
4621<div class="doc_text">
4622
4623<h5>Syntax:</h5>
4624<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
4625floating point or vector of floating point type. Not all targets support all
4626types however.
4627<pre>
4628 declare float @llvm.sin.f32(float %Val)
4629 declare double @llvm.sin.f64(double %Val)
4630 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
4631 declare fp128 @llvm.sin.f128(fp128 %Val)
4632 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
4633</pre>
4634
4635<h5>Overview:</h5>
4636
4637<p>
4638The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
4639</p>
4640
4641<h5>Arguments:</h5>
4642
4643<p>
4644The argument and return value are floating point numbers of the same type.
4645</p>
4646
4647<h5>Semantics:</h5>
4648
4649<p>
4650This function returns the sine of the specified operand, returning the
4651same values as the libm <tt>sin</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4652conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4653</div>
4654
4655<!-- _______________________________________________________________________ -->
4656<div class="doc_subsubsection">
4657 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
4658</div>
4659
4660<div class="doc_text">
4661
4662<h5>Syntax:</h5>
4663<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
4664floating point or vector of floating point type. Not all targets support all
4665types however.
4666<pre>
4667 declare float @llvm.cos.f32(float %Val)
4668 declare double @llvm.cos.f64(double %Val)
4669 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
4670 declare fp128 @llvm.cos.f128(fp128 %Val)
4671 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
4672</pre>
4673
4674<h5>Overview:</h5>
4675
4676<p>
4677The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
4678</p>
4679
4680<h5>Arguments:</h5>
4681
4682<p>
4683The argument and return value are floating point numbers of the same type.
4684</p>
4685
4686<h5>Semantics:</h5>
4687
4688<p>
4689This function returns the cosine of the specified operand, returning the
4690same values as the libm <tt>cos</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4691conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4692</div>
4693
4694<!-- _______________________________________________________________________ -->
4695<div class="doc_subsubsection">
4696 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
4697</div>
4698
4699<div class="doc_text">
4700
4701<h5>Syntax:</h5>
4702<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
4703floating point or vector of floating point type. Not all targets support all
4704types however.
4705<pre>
4706 declare float @llvm.pow.f32(float %Val, float %Power)
4707 declare double @llvm.pow.f64(double %Val, double %Power)
4708 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
4709 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
4710 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
4711</pre>
4712
4713<h5>Overview:</h5>
4714
4715<p>
4716The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
4717specified (positive or negative) power.
4718</p>
4719
4720<h5>Arguments:</h5>
4721
4722<p>
4723The second argument is a floating point power, and the first is a value to
4724raise to that power.
4725</p>
4726
4727<h5>Semantics:</h5>
4728
4729<p>
4730This function returns the first value raised to the second power,
4731returning the
4732same values as the libm <tt>pow</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4733conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4734</div>
4735
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4736
4737<!-- ======================================================================= -->
4738<div class="doc_subsection">
4739 <a name="int_manip">Bit Manipulation Intrinsics</a>
4740</div>
4741
4742<div class="doc_text">
4743<p>
4744LLVM provides intrinsics for a few important bit manipulation operations.
4745These allow efficient code generation for some algorithms.
4746</p>
4747
4748</div>
4749
4750<!-- _______________________________________________________________________ -->
4751<div class="doc_subsubsection">
4752 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4753</div>
4754
4755<div class="doc_text">
4756
4757<h5>Syntax:</h5>
4758<p>This is an overloaded intrinsic function. You can use bswap on any integer
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4759type that is an even number of bytes (i.e. BitWidth % 16 == 0).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4760<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4761 declare i16 @llvm.bswap.i16(i16 &lt;id&gt;)
4762 declare i32 @llvm.bswap.i32(i32 &lt;id&gt;)
4763 declare i64 @llvm.bswap.i64(i64 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4764</pre>
4765
4766<h5>Overview:</h5>
4767
4768<p>
4769The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
4770values with an even number of bytes (positive multiple of 16 bits). These are
4771useful for performing operations on data that is not in the target's native
4772byte order.
4773</p>
4774
4775<h5>Semantics:</h5>
4776
4777<p>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4778The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4779and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4780intrinsic returns an i32 value that has the four bytes of the input i32
4781swapped, 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]4782i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
4783<tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4784additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
4785</p>
4786
4787</div>
4788
4789<!-- _______________________________________________________________________ -->
4790<div class="doc_subsubsection">
4791 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
4792</div>
4793
4794<div class="doc_text">
4795
4796<h5>Syntax:</h5>
4797<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4798width. Not all targets support all bit widths however.
4799<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4800 declare i8 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4801 declare i16 @llvm.ctpop.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4802 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4803 declare i64 @llvm.ctpop.i64(i64 &lt;src&gt;)
4804 declare i256 @llvm.ctpop.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4805</pre>
4806
4807<h5>Overview:</h5>
4808
4809<p>
4810The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4811value.
4812</p>
4813
4814<h5>Arguments:</h5>
4815
4816<p>
4817The only argument is the value to be counted. The argument may be of any
4818integer type. The return type must match the argument type.
4819</p>
4820
4821<h5>Semantics:</h5>
4822
4823<p>
4824The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4825</p>
4826</div>
4827
4828<!-- _______________________________________________________________________ -->
4829<div class="doc_subsubsection">
4830 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
4831</div>
4832
4833<div class="doc_text">
4834
4835<h5>Syntax:</h5>
4836<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4837integer bit width. Not all targets support all bit widths however.
4838<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4839 declare i8 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4840 declare i16 @llvm.ctlz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4841 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4842 declare i64 @llvm.ctlz.i64(i64 &lt;src&gt;)
4843 declare i256 @llvm.ctlz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4844</pre>
4845
4846<h5>Overview:</h5>
4847
4848<p>
4849The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4850leading zeros in a variable.
4851</p>
4852
4853<h5>Arguments:</h5>
4854
4855<p>
4856The only argument is the value to be counted. The argument may be of any
4857integer type. The return type must match the argument type.
4858</p>
4859
4860<h5>Semantics:</h5>
4861
4862<p>
4863The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4864in a variable. If the src == 0 then the result is the size in bits of the type
4865of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
4866</p>
4867</div>
4868
4869
4870
4871<!-- _______________________________________________________________________ -->
4872<div class="doc_subsubsection">
4873 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
4874</div>
4875
4876<div class="doc_text">
4877
4878<h5>Syntax:</h5>
4879<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4880integer bit width. Not all targets support all bit widths however.
4881<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4882 declare i8 @llvm.cttz.i8 (i8 &lt;src&gt;)
4883 declare i16 @llvm.cttz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4884 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4885 declare i64 @llvm.cttz.i64(i64 &lt;src&gt;)
4886 declare i256 @llvm.cttz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4887</pre>
4888
4889<h5>Overview:</h5>
4890
4891<p>
4892The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4893trailing zeros.
4894</p>
4895
4896<h5>Arguments:</h5>
4897
4898<p>
4899The only argument is the value to be counted. The argument may be of any
4900integer type. The return type must match the argument type.
4901</p>
4902
4903<h5>Semantics:</h5>
4904
4905<p>
4906The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4907in a variable. If the src == 0 then the result is the size in bits of the type
4908of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4909</p>
4910</div>
4911
4912<!-- _______________________________________________________________________ -->
4913<div class="doc_subsubsection">
4914 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
4915</div>
4916
4917<div class="doc_text">
4918
4919<h5>Syntax:</h5>
4920<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
4921on any integer bit width.
4922<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4923 declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
4924 declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4925</pre>
4926
4927<h5>Overview:</h5>
4928<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
4929range of bits from an integer value and returns them in the same bit width as
4930the original value.</p>
4931
4932<h5>Arguments:</h5>
4933<p>The first argument, <tt>%val</tt> and the result may be integer types of
4934any bit width but they must have the same bit width. The second and third
4935arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
4936
4937<h5>Semantics:</h5>
4938<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
4939of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
4940<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
4941operates in forward mode.</p>
4942<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
4943right by <tt>%loBit</tt> bits and then ANDing it with a mask with
4944only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
4945<ol>
4946 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
4947 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
4948 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
4949 to determine the number of bits to retain.</li>
4950 <li>A mask of the retained bits is created by shifting a -1 value.</li>
4951 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
4952</ol>
4953<p>In reverse mode, a similar computation is made except that the bits are
4954returned in the reverse order. So, for example, if <tt>X</tt> has the value
4955<tt>i16 0x0ACF (101011001111)</tt> and we apply
4956<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
4957<tt>i16 0x0026 (000000100110)</tt>.</p>
4958</div>
4959
4960<div class="doc_subsubsection">
4961 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
4962</div>
4963
4964<div class="doc_text">
4965
4966<h5>Syntax:</h5>
4967<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
4968on any integer bit width.
4969<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4970 declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
4971 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]4972</pre>
4973
4974<h5>Overview:</h5>
4975<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
4976of bits in an integer value with another integer value. It returns the integer
4977with the replaced bits.</p>
4978
4979<h5>Arguments:</h5>
4980<p>The first argument, <tt>%val</tt> and the result may be integer types of
4981any bit width but they must have the same bit width. <tt>%val</tt> is the value
4982whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
4983integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
4984type since they specify only a bit index.</p>
4985
4986<h5>Semantics:</h5>
4987<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
4988of operation: forwards and reverse. If <tt>%lo</tt> is greater than
4989<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
4990operates in forward mode.</p>
4991<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
4992truncating it down to the size of the replacement area or zero extending it
4993up to that size.</p>
4994<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
4995are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
4996in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
4997to the <tt>%hi</tt>th bit.
4998<p>In reverse mode, a similar computation is made except that the bits are
4999reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
5000<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
5001<h5>Examples:</h5>
5002<pre>
5003 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
5004 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0xFF0F
5005 llvm.part.set(0xFFFF, 1, 7, 4) -&gt; 0xFF8F
5006 llvm.part.set(0xFFFF, F, 8, 3) -&gt; 0xFFE7
5007 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
5008</pre>
5009</div>
5010
5011<!-- ======================================================================= -->
5012<div class="doc_subsection">
5013 <a name="int_debugger">Debugger Intrinsics</a>
5014</div>
5015
5016<div class="doc_text">
5017<p>
5018The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
5019are described in the <a
5020href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
5021Debugging</a> document.
5022</p>
5023</div>
5024
5025
5026<!-- ======================================================================= -->
5027<div class="doc_subsection">
5028 <a name="int_eh">Exception Handling Intrinsics</a>
5029</div>
5030
5031<div class="doc_text">
5032<p> The LLVM exception handling intrinsics (which all start with
5033<tt>llvm.eh.</tt> prefix), are described in the <a
5034href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
5035Handling</a> document. </p>
5036</div>
5037
5038<!-- ======================================================================= -->
5039<div class="doc_subsection">
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5040 <a name="int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5041</div>
5042
5043<div class="doc_text">
5044<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5045 This intrinsic makes it possible to excise one parameter, marked with
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5046 the <tt>nest</tt> attribute, from a function. The result is a callable
5047 function pointer lacking the nest parameter - the caller does not need
5048 to provide a value for it. Instead, the value to use is stored in
5049 advance in a "trampoline", a block of memory usually allocated
5050 on the stack, which also contains code to splice the nest value into the
5051 argument list. This is used to implement the GCC nested function address
5052 extension.
5053</p>
5054<p>
5055 For example, if the function is
5056 <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]5057 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]5058<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5059 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
5060 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
5061 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
5062 %fp = bitcast i8* %p to i32 (i32, i32)*
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5063</pre>
Bill Wendlinge262b4c2007-09-22 09:23:55 +0000[diff] [blame]5064 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
5065 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5066</div>
5067
5068<!-- _______________________________________________________________________ -->
5069<div class="doc_subsubsection">
5070 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
5071</div>
5072<div class="doc_text">
5073<h5>Syntax:</h5>
5074<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5075declare 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]5076</pre>
5077<h5>Overview:</h5>
5078<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5079 This fills the memory pointed to by <tt>tramp</tt> with code
5080 and returns a function pointer suitable for executing it.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5081</p>
5082<h5>Arguments:</h5>
5083<p>
5084 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
5085 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
5086 and sufficiently aligned block of memory; this memory is written to by the
Duncan Sands35012212007-08-22 23:39:54 +0000[diff] [blame]5087 intrinsic. Note that the size and the alignment are target-specific - LLVM
5088 currently provides no portable way of determining them, so a front-end that
5089 generates this intrinsic needs to have some target-specific knowledge.
5090 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]5091</p>
5092<h5>Semantics:</h5>
5093<p>
5094 The block of memory pointed to by <tt>tramp</tt> is filled with target
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5095 dependent code, turning it into a function. A pointer to this function is
5096 returned, but needs to be bitcast to an
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5097 <a href="#int_trampoline">appropriate function pointer type</a>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5098 before being called. The new function's signature is the same as that of
5099 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
5100 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
5101 of pointer type. Calling the new function is equivalent to calling
5102 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
5103 missing <tt>nest</tt> argument. If, after calling
5104 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
5105 modified, then the effect of any later call to the returned function pointer is
5106 undefined.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5107</p>
5108</div>
5109
5110<!-- ======================================================================= -->
5111<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5112 <a name="int_general">General Intrinsics</a>
5113</div>
5114
5115<div class="doc_text">
5116<p> This class of intrinsics is designed to be generic and has
5117no specific purpose. </p>
5118</div>
5119
5120<!-- _______________________________________________________________________ -->
5121<div class="doc_subsubsection">
5122 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
5123</div>
5124
5125<div class="doc_text">
5126
5127<h5>Syntax:</h5>
5128<pre>
5129 declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5130</pre>
5131
5132<h5>Overview:</h5>
5133
5134<p>
5135The '<tt>llvm.var.annotation</tt>' intrinsic
5136</p>
5137
5138<h5>Arguments:</h5>
5139
5140<p>
5141The first argument is a pointer to a value, the second is a pointer to a
5142global string, the third is a pointer to a global string which is the source
5143file name, and the last argument is the line number.
5144</p>
5145
5146<h5>Semantics:</h5>
5147
5148<p>
5149This intrinsic allows annotation of local variables with arbitrary strings.
5150This can be useful for special purpose optimizations that want to look for these
5151 annotations. These have no other defined use, they are ignored by code
5152 generation and optimization.
5153</div>
5154
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5155<!-- _______________________________________________________________________ -->
5156<div class="doc_subsubsection">
Tanya Lattnerc9869b12007-09-21 23:57:59 +0000[diff] [blame]5157 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5158</div>
5159
5160<div class="doc_text">
5161
5162<h5>Syntax:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5163<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
5164any integer bit width.
5165</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5166<pre>
Tanya Lattner09161fe2007-09-22 00:03:01 +0000[diff] [blame]5167 declare i8 @llvm.annotation.i8(i8 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5168 declare i16 @llvm.annotation.i16(i16 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5169 declare i32 @llvm.annotation.i32(i32 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5170 declare i64 @llvm.annotation.i64(i64 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5171 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]5172</pre>
5173
5174<h5>Overview:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5175
5176<p>
5177The '<tt>llvm.annotation</tt>' intrinsic.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5178</p>
5179
5180<h5>Arguments:</h5>
5181
5182<p>
5183The first argument is an integer value (result of some expression),
5184the second is a pointer to a global string, the third is a pointer to a global
5185string which is the source file name, and the last argument is the line number.
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5186It returns the value of the first argument.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5187</p>
5188
5189<h5>Semantics:</h5>
5190
5191<p>
5192This intrinsic allows annotations to be put on arbitrary expressions
5193with arbitrary strings. This can be useful for special purpose optimizations
5194that want to look for these annotations. These have no other defined use, they
5195are ignored by code generation and optimization.
5196</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5197
5198<!-- *********************************************************************** -->
5199<hr>
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5205
5206 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
5207 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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