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5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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13<body>
14
15<div class="doc_title"> LLVM Language Reference Manual </div>
16<ol>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
23 <li><a href="#linkage">Linkage Types</a></li>
24 <li><a href="#callingconv">Calling Conventions</a></li>
25 <li><a href="#globalvars">Global Variables</a></li>
26 <li><a href="#functionstructure">Functions</a></li>
27 <li><a href="#aliasstructure">Aliases</a>
28 <li><a href="#paramattrs">Parameter Attributes</a></li>
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]29 <li><a href="#gc">Garbage Collector Names</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]30 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
31 <li><a href="#datalayout">Data Layout</a></li>
32 </ol>
33 </li>
34 <li><a href="#typesystem">Type System</a>
35 <ol>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]36 <li><a href="#t_classifications">Type Classifications</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]37 <li><a href="#t_primitive">Primitive Types</a>
38 <ol>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]39 <li><a href="#t_floating">Floating Point Types</a></li>
40 <li><a href="#t_void">Void Type</a></li>
41 <li><a href="#t_label">Label Type</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]42 </ol>
43 </li>
44 <li><a href="#t_derived">Derived Types</a>
45 <ol>
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]46 <li><a href="#t_integer">Integer Type</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]47 <li><a href="#t_array">Array Type</a></li>
48 <li><a href="#t_function">Function Type</a></li>
49 <li><a href="#t_pointer">Pointer Type</a></li>
50 <li><a href="#t_struct">Structure Type</a></li>
51 <li><a href="#t_pstruct">Packed Structure Type</a></li>
52 <li><a href="#t_vector">Vector Type</a></li>
53 <li><a href="#t_opaque">Opaque Type</a></li>
54 </ol>
55 </li>
56 </ol>
57 </li>
58 <li><a href="#constants">Constants</a>
59 <ol>
60 <li><a href="#simpleconstants">Simple Constants</a>
61 <li><a href="#aggregateconstants">Aggregate Constants</a>
62 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
63 <li><a href="#undefvalues">Undefined Values</a>
64 <li><a href="#constantexprs">Constant Expressions</a>
65 </ol>
66 </li>
67 <li><a href="#othervalues">Other Values</a>
68 <ol>
69 <li><a href="#inlineasm">Inline Assembler Expressions</a>
70 </ol>
71 </li>
72 <li><a href="#instref">Instruction Reference</a>
73 <ol>
74 <li><a href="#terminators">Terminator Instructions</a>
75 <ol>
76 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
77 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
78 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
79 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
80 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
81 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
82 </ol>
83 </li>
84 <li><a href="#binaryops">Binary Operations</a>
85 <ol>
86 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
87 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
88 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
89 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
90 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
91 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
92 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
93 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
94 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
95 </ol>
96 </li>
97 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
98 <ol>
99 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
100 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
101 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
102 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
103 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
104 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
105 </ol>
106 </li>
107 <li><a href="#vectorops">Vector Operations</a>
108 <ol>
109 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
110 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
111 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
112 </ol>
113 </li>
114 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
115 <ol>
116 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
117 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
118 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
119 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
120 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
121 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
122 </ol>
123 </li>
124 <li><a href="#convertops">Conversion Operations</a>
125 <ol>
126 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
127 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
128 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
129 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
130 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
131 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
132 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
133 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
134 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
135 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
136 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
137 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
138 </ol>
139 <li><a href="#otherops">Other Operations</a>
140 <ol>
141 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
142 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
143 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
144 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
145 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
146 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
147 </ol>
148 </li>
149 </ol>
150 </li>
151 <li><a href="#intrinsics">Intrinsic Functions</a>
152 <ol>
153 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
154 <ol>
155 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
156 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
157 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
158 </ol>
159 </li>
160 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
161 <ol>
162 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
163 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
164 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
165 </ol>
166 </li>
167 <li><a href="#int_codegen">Code Generator Intrinsics</a>
168 <ol>
169 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
170 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
171 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
172 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
173 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
174 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
175 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
176 </ol>
177 </li>
178 <li><a href="#int_libc">Standard C Library Intrinsics</a>
179 <ol>
180 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
181 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
182 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
183 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
184 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]185 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
186 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
187 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]188 </ol>
189 </li>
190 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
191 <ol>
192 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
193 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
194 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
195 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
196 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
197 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
198 </ol>
199 </li>
200 <li><a href="#int_debugger">Debugger intrinsics</a></li>
201 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]202 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]203 <ol>
204 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]205 </ol>
206 </li>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]207 <li><a href="#int_general">General intrinsics</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]208 <ol>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]209 <li><a href="#int_var_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]210 <tt>llvm.var.annotation</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]211 <li><a href="#int_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]212 <tt>llvm.annotation.*</tt>' Intrinsic</a></li>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame^]213 <li><a href="#int_trap">
214 <tt>llvm.trap</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]215 </ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]216 </li>
217 </ol>
218 </li>
219</ol>
220
221<div class="doc_author">
222 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
223 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
224</div>
225
226<!-- *********************************************************************** -->
227<div class="doc_section"> <a name="abstract">Abstract </a></div>
228<!-- *********************************************************************** -->
229
230<div class="doc_text">
231<p>This document is a reference manual for the LLVM assembly language.
232LLVM is an SSA based representation that provides type safety,
233low-level operations, flexibility, and the capability of representing
234'all' high-level languages cleanly. It is the common code
235representation used throughout all phases of the LLVM compilation
236strategy.</p>
237</div>
238
239<!-- *********************************************************************** -->
240<div class="doc_section"> <a name="introduction">Introduction</a> </div>
241<!-- *********************************************************************** -->
242
243<div class="doc_text">
244
245<p>The LLVM code representation is designed to be used in three
246different forms: as an in-memory compiler IR, as an on-disk bitcode
247representation (suitable for fast loading by a Just-In-Time compiler),
248and as a human readable assembly language representation. This allows
249LLVM to provide a powerful intermediate representation for efficient
250compiler transformations and analysis, while providing a natural means
251to debug and visualize the transformations. The three different forms
252of LLVM are all equivalent. This document describes the human readable
253representation and notation.</p>
254
255<p>The LLVM representation aims to be light-weight and low-level
256while being expressive, typed, and extensible at the same time. It
257aims to be a "universal IR" of sorts, by being at a low enough level
258that high-level ideas may be cleanly mapped to it (similar to how
259microprocessors are "universal IR's", allowing many source languages to
260be mapped to them). By providing type information, LLVM can be used as
261the target of optimizations: for example, through pointer analysis, it
262can be proven that a C automatic variable is never accessed outside of
263the current function... allowing it to be promoted to a simple SSA
264value instead of a memory location.</p>
265
266</div>
267
268<!-- _______________________________________________________________________ -->
269<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
270
271<div class="doc_text">
272
273<p>It is important to note that this document describes 'well formed'
274LLVM assembly language. There is a difference between what the parser
275accepts and what is considered 'well formed'. For example, the
276following instruction is syntactically okay, but not well formed:</p>
277
278<div class="doc_code">
279<pre>
280%x = <a href="#i_add">add</a> i32 1, %x
281</pre>
282</div>
283
284<p>...because the definition of <tt>%x</tt> does not dominate all of
285its uses. The LLVM infrastructure provides a verification pass that may
286be used to verify that an LLVM module is well formed. This pass is
287automatically run by the parser after parsing input assembly and by
288the optimizer before it outputs bitcode. The violations pointed out
289by the verifier pass indicate bugs in transformation passes or input to
290the parser.</p>
291</div>
292
Chris Lattnera83fdc02007-10-03 17:34:29 +0000[diff] [blame]293<!-- Describe the typesetting conventions here. -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]294
295<!-- *********************************************************************** -->
296<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
297<!-- *********************************************************************** -->
298
299<div class="doc_text">
300
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]301 <p>LLVM identifiers come in two basic types: global and local. Global
302 identifiers (functions, global variables) begin with the @ character. Local
303 identifiers (register names, types) begin with the % character. Additionally,
304 there are three different formats for identifiers, for different purposes:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]305
306<ol>
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]307 <li>Named values are represented as a string of characters with their prefix.
308 For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
309 regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]310 Identifiers which require other characters in their names can be surrounded
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]311 with quotes. In this way, anything except a <tt>&quot;</tt> character can
312 be used in a named value.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]313
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]314 <li>Unnamed values are represented as an unsigned numeric value with their
315 prefix. For example, %12, @2, %44.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]316
317 <li>Constants, which are described in a <a href="#constants">section about
318 constants</a>, below.</li>
319</ol>
320
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]321<p>LLVM requires that values start with a prefix for two reasons: Compilers
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]322don't need to worry about name clashes with reserved words, and the set of
323reserved words may be expanded in the future without penalty. Additionally,
324unnamed identifiers allow a compiler to quickly come up with a temporary
325variable without having to avoid symbol table conflicts.</p>
326
327<p>Reserved words in LLVM are very similar to reserved words in other
328languages. There are keywords for different opcodes
329('<tt><a href="#i_add">add</a></tt>',
330 '<tt><a href="#i_bitcast">bitcast</a></tt>',
331 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
332href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
333and others. These reserved words cannot conflict with variable names, because
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]334none of them start with a prefix character ('%' or '@').</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]335
336<p>Here is an example of LLVM code to multiply the integer variable
337'<tt>%X</tt>' by 8:</p>
338
339<p>The easy way:</p>
340
341<div class="doc_code">
342<pre>
343%result = <a href="#i_mul">mul</a> i32 %X, 8
344</pre>
345</div>
346
347<p>After strength reduction:</p>
348
349<div class="doc_code">
350<pre>
351%result = <a href="#i_shl">shl</a> i32 %X, i8 3
352</pre>
353</div>
354
355<p>And the hard way:</p>
356
357<div class="doc_code">
358<pre>
359<a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
360<a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
361%result = <a href="#i_add">add</a> i32 %1, %1
362</pre>
363</div>
364
365<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
366important lexical features of LLVM:</p>
367
368<ol>
369
370 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
371 line.</li>
372
373 <li>Unnamed temporaries are created when the result of a computation is not
374 assigned to a named value.</li>
375
376 <li>Unnamed temporaries are numbered sequentially</li>
377
378</ol>
379
380<p>...and it also shows a convention that we follow in this document. When
381demonstrating instructions, we will follow an instruction with a comment that
382defines the type and name of value produced. Comments are shown in italic
383text.</p>
384
385</div>
386
387<!-- *********************************************************************** -->
388<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
389<!-- *********************************************************************** -->
390
391<!-- ======================================================================= -->
392<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
393</div>
394
395<div class="doc_text">
396
397<p>LLVM programs are composed of "Module"s, each of which is a
398translation unit of the input programs. Each module consists of
399functions, global variables, and symbol table entries. Modules may be
400combined together with the LLVM linker, which merges function (and
401global variable) definitions, resolves forward declarations, and merges
402symbol table entries. Here is an example of the "hello world" module:</p>
403
404<div class="doc_code">
405<pre><i>; Declare the string constant as a global constant...</i>
406<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
407 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
408
409<i>; External declaration of the puts function</i>
410<a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
411
412<i>; Definition of main function</i>
413define i32 @main() { <i>; i32()* </i>
414 <i>; Convert [13x i8 ]* to i8 *...</i>
415 %cast210 = <a
416 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
417
418 <i>; Call puts function to write out the string to stdout...</i>
419 <a
420 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
421 <a
422 href="#i_ret">ret</a> i32 0<br>}<br>
423</pre>
424</div>
425
426<p>This example is made up of a <a href="#globalvars">global variable</a>
427named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
428function, and a <a href="#functionstructure">function definition</a>
429for "<tt>main</tt>".</p>
430
431<p>In general, a module is made up of a list of global values,
432where both functions and global variables are global values. Global values are
433represented by a pointer to a memory location (in this case, a pointer to an
434array of char, and a pointer to a function), and have one of the following <a
435href="#linkage">linkage types</a>.</p>
436
437</div>
438
439<!-- ======================================================================= -->
440<div class="doc_subsection">
441 <a name="linkage">Linkage Types</a>
442</div>
443
444<div class="doc_text">
445
446<p>
447All Global Variables and Functions have one of the following types of linkage:
448</p>
449
450<dl>
451
452 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
453
454 <dd>Global values with internal linkage are only directly accessible by
455 objects in the current module. In particular, linking code into a module with
456 an internal global value may cause the internal to be renamed as necessary to
457 avoid collisions. Because the symbol is internal to the module, all
458 references can be updated. This corresponds to the notion of the
459 '<tt>static</tt>' keyword in C.
460 </dd>
461
462 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
463
464 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
465 the same name when linkage occurs. This is typically used to implement
466 inline functions, templates, or other code which must be generated in each
467 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
468 allowed to be discarded.
469 </dd>
470
471 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
472
473 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
474 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
475 used for globals that may be emitted in multiple translation units, but that
476 are not guaranteed to be emitted into every translation unit that uses them.
477 One example of this are common globals in C, such as "<tt>int X;</tt>" at
478 global scope.
479 </dd>
480
481 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
482
483 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
484 pointer to array type. When two global variables with appending linkage are
485 linked together, the two global arrays are appended together. This is the
486 LLVM, typesafe, equivalent of having the system linker append together
487 "sections" with identical names when .o files are linked.
488 </dd>
489
490 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
491 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
492 until linked, if not linked, the symbol becomes null instead of being an
493 undefined reference.
494 </dd>
495
496 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
497
498 <dd>If none of the above identifiers are used, the global is externally
499 visible, meaning that it participates in linkage and can be used to resolve
500 external symbol references.
501 </dd>
502</dl>
503
504 <p>
505 The next two types of linkage are targeted for Microsoft Windows platform
506 only. They are designed to support importing (exporting) symbols from (to)
507 DLLs.
508 </p>
509
510 <dl>
511 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
512
513 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
514 or variable via a global pointer to a pointer that is set up by the DLL
515 exporting the symbol. On Microsoft Windows targets, the pointer name is
516 formed by combining <code>_imp__</code> and the function or variable name.
517 </dd>
518
519 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
520
521 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
522 pointer to a pointer in a DLL, so that it can be referenced with the
523 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
524 name is formed by combining <code>_imp__</code> and the function or variable
525 name.
526 </dd>
527
528</dl>
529
530<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
531variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
532variable and was linked with this one, one of the two would be renamed,
533preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
534external (i.e., lacking any linkage declarations), they are accessible
535outside of the current module.</p>
536<p>It is illegal for a function <i>declaration</i>
537to have any linkage type other than "externally visible", <tt>dllimport</tt>,
538or <tt>extern_weak</tt>.</p>
539<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
540linkages.
541</div>
542
543<!-- ======================================================================= -->
544<div class="doc_subsection">
545 <a name="callingconv">Calling Conventions</a>
546</div>
547
548<div class="doc_text">
549
550<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
551and <a href="#i_invoke">invokes</a> can all have an optional calling convention
552specified for the call. The calling convention of any pair of dynamic
553caller/callee must match, or the behavior of the program is undefined. The
554following calling conventions are supported by LLVM, and more may be added in
555the future:</p>
556
557<dl>
558 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
559
560 <dd>This calling convention (the default if no other calling convention is
561 specified) matches the target C calling conventions. This calling convention
562 supports varargs function calls and tolerates some mismatch in the declared
563 prototype and implemented declaration of the function (as does normal C).
564 </dd>
565
566 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
567
568 <dd>This calling convention attempts to make calls as fast as possible
569 (e.g. by passing things in registers). This calling convention allows the
570 target to use whatever tricks it wants to produce fast code for the target,
571 without having to conform to an externally specified ABI. Implementations of
572 this convention should allow arbitrary tail call optimization to be supported.
573 This calling convention does not support varargs and requires the prototype of
574 all callees to exactly match the prototype of the function definition.
575 </dd>
576
577 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
578
579 <dd>This calling convention attempts to make code in the caller as efficient
580 as possible under the assumption that the call is not commonly executed. As
581 such, these calls often preserve all registers so that the call does not break
582 any live ranges in the caller side. This calling convention does not support
583 varargs and requires the prototype of all callees to exactly match the
584 prototype of the function definition.
585 </dd>
586
587 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
588
589 <dd>Any calling convention may be specified by number, allowing
590 target-specific calling conventions to be used. Target specific calling
591 conventions start at 64.
592 </dd>
593</dl>
594
595<p>More calling conventions can be added/defined on an as-needed basis, to
596support pascal conventions or any other well-known target-independent
597convention.</p>
598
599</div>
600
601<!-- ======================================================================= -->
602<div class="doc_subsection">
603 <a name="visibility">Visibility Styles</a>
604</div>
605
606<div class="doc_text">
607
608<p>
609All Global Variables and Functions have one of the following visibility styles:
610</p>
611
612<dl>
613 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
614
615 <dd>On ELF, default visibility means that the declaration is visible to other
616 modules and, in shared libraries, means that the declared entity may be
617 overridden. On Darwin, default visibility means that the declaration is
618 visible to other modules. Default visibility corresponds to "external
619 linkage" in the language.
620 </dd>
621
622 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
623
624 <dd>Two declarations of an object with hidden visibility refer to the same
625 object if they are in the same shared object. Usually, hidden visibility
626 indicates that the symbol will not be placed into the dynamic symbol table,
627 so no other module (executable or shared library) can reference it
628 directly.
629 </dd>
630
631 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
632
633 <dd>On ELF, protected visibility indicates that the symbol will be placed in
634 the dynamic symbol table, but that references within the defining module will
635 bind to the local symbol. That is, the symbol cannot be overridden by another
636 module.
637 </dd>
638</dl>
639
640</div>
641
642<!-- ======================================================================= -->
643<div class="doc_subsection">
644 <a name="globalvars">Global Variables</a>
645</div>
646
647<div class="doc_text">
648
649<p>Global variables define regions of memory allocated at compilation time
650instead of run-time. Global variables may optionally be initialized, may have
651an explicit section to be placed in, and may have an optional explicit alignment
652specified. A variable may be defined as "thread_local", which means that it
653will not be shared by threads (each thread will have a separated copy of the
654variable). A variable may be defined as a global "constant," which indicates
655that the contents of the variable will <b>never</b> be modified (enabling better
656optimization, allowing the global data to be placed in the read-only section of
657an executable, etc). Note that variables that need runtime initialization
658cannot be marked "constant" as there is a store to the variable.</p>
659
660<p>
661LLVM explicitly allows <em>declarations</em> of global variables to be marked
662constant, even if the final definition of the global is not. This capability
663can be used to enable slightly better optimization of the program, but requires
664the language definition to guarantee that optimizations based on the
665'constantness' are valid for the translation units that do not include the
666definition.
667</p>
668
669<p>As SSA values, global variables define pointer values that are in
670scope (i.e. they dominate) all basic blocks in the program. Global
671variables always define a pointer to their "content" type because they
672describe a region of memory, and all memory objects in LLVM are
673accessed through pointers.</p>
674
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]675<p>A global variable may be declared to reside in a target-specifc numbered
676address space. For targets that support them, address spaces may affect how
677optimizations are performed and/or what target instructions are used to access
Christopher Lamb20a39e92007-12-12 08:44:39 +0000[diff] [blame]678the variable. The default address space is zero. The address space qualifier
679must precede any other attributes.</p>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]680
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]681<p>LLVM allows an explicit section to be specified for globals. If the target
682supports it, it will emit globals to the section specified.</p>
683
684<p>An explicit alignment may be specified for a global. If not present, or if
685the alignment is set to zero, the alignment of the global is set by the target
686to whatever it feels convenient. If an explicit alignment is specified, the
687global is forced to have at least that much alignment. All alignments must be
688a power of 2.</p>
689
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]690<p>For example, the following defines a global in a numbered address space with
691an initializer, section, and alignment:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]692
693<div class="doc_code">
694<pre>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]695@G = constant float 1.0 addrspace(5), section "foo", align 4
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]696</pre>
697</div>
698
699</div>
700
701
702<!-- ======================================================================= -->
703<div class="doc_subsection">
704 <a name="functionstructure">Functions</a>
705</div>
706
707<div class="doc_text">
708
709<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
710an optional <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
714name, a (possibly empty) argument list (each with optional
715<a href="#paramattrs">parameter attributes</a>), an optional section, an
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]716optional alignment, an optional <a href="#gc">garbage collector name</a>, an
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]717opening curly brace, a list of basic blocks, and a closing curly brace.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]718
719LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
720optional <a href="#linkage">linkage type</a>, an optional
721<a href="#visibility">visibility style</a>, an optional
722<a href="#callingconv">calling convention</a>, a return type, an optional
723<a href="#paramattrs">parameter attribute</a> for the return type, a function
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]724name, a possibly empty list of arguments, an optional alignment, and an optional
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]725<a href="#gc">garbage collector name</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]726
727<p>A function definition contains a list of basic blocks, forming the CFG for
728the function. Each basic block may optionally start with a label (giving the
729basic block a symbol table entry), contains a list of instructions, and ends
730with a <a href="#terminators">terminator</a> instruction (such as a branch or
731function return).</p>
732
733<p>The first basic block in a function is special in two ways: it is immediately
734executed on entrance to the function, and it is not allowed to have predecessor
735basic blocks (i.e. there can not be any branches to the entry block of a
736function). Because the block can have no predecessors, it also cannot have any
737<a href="#i_phi">PHI nodes</a>.</p>
738
739<p>LLVM allows an explicit section to be specified for functions. If the target
740supports it, it will emit functions to the section specified.</p>
741
742<p>An explicit alignment may be specified for a function. If not present, or if
743the alignment is set to zero, the alignment of the function is set by the target
744to whatever it feels convenient. If an explicit alignment is specified, the
745function is forced to have at least that much alignment. All alignments must be
746a power of 2.</p>
747
748</div>
749
750
751<!-- ======================================================================= -->
752<div class="doc_subsection">
753 <a name="aliasstructure">Aliases</a>
754</div>
755<div class="doc_text">
756 <p>Aliases act as "second name" for the aliasee value (which can be either
757 function or global variable or bitcast of global value). Aliases may have an
758 optional <a href="#linkage">linkage type</a>, and an
759 optional <a href="#visibility">visibility style</a>.</p>
760
761 <h5>Syntax:</h5>
762
763<div class="doc_code">
764<pre>
765@&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
766</pre>
767</div>
768
769</div>
770
771
772
773<!-- ======================================================================= -->
774<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
775<div class="doc_text">
776 <p>The return type and each parameter of a function type may have a set of
777 <i>parameter attributes</i> associated with them. Parameter attributes are
778 used to communicate additional information about the result or parameters of
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]779 a function. Parameter attributes are considered to be part of the function,
780 not of the function type, so functions with different parameter attributes
781 can have the same function type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]782
783 <p>Parameter attributes are simple keywords that follow the type specified. If
784 multiple parameter attributes are needed, they are space separated. For
785 example:</p>
786
787<div class="doc_code">
788<pre>
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]789declare i32 @printf(i8* noalias , ...) nounwind
790declare i32 @atoi(i8*) nounwind readonly
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]791</pre>
792</div>
793
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]794 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
795 <tt>readonly</tt>) come immediately after the argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]796
797 <p>Currently, only the following parameter attributes are defined:</p>
798 <dl>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]799 <dt><tt>zeroext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]800 <dd>This indicates that the parameter should be zero extended just before
801 a call to this function.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]802
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]803 <dt><tt>signext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]804 <dd>This indicates that the parameter should be sign extended just before
805 a call to this function.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]806
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]807 <dt><tt>inreg</tt></dt>
808 <dd>This indicates that the parameter should be placed in register (if
809 possible) during assembling function call. Support for this attribute is
810 target-specific</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]811
812 <dt><tt>byval</tt></dt>
Chris Lattner04c86182008-01-15 04:34:22 +0000[diff] [blame]813 <dd>This indicates that the pointer parameter should really be passed by
814 value to the function. The attribute implies that a hidden copy of the
815 pointee is made between the caller and the callee, so the callee is unable
816 to modify the value in the callee. This attribute is only valid on llvm
817 pointer arguments. It is generally used to pass structs and arrays by
818 value, but is also valid on scalars (even though this is silly).</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]819
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]820 <dt><tt>sret</tt></dt>
821 <dd>This indicates that the parameter specifies the address of a structure
822 that is the return value of the function in the source program.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]823
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]824 <dt><tt>noalias</tt></dt>
825 <dd>This indicates that the parameter not alias any other object or any
826 other "noalias" objects during the function call.
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]827
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]828 <dt><tt>noreturn</tt></dt>
829 <dd>This function attribute indicates that the function never returns. This
830 indicates to LLVM that every call to this function should be treated as if
831 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]832
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]833 <dt><tt>nounwind</tt></dt>
834 <dd>This function attribute indicates that the function type does not use
835 the unwind instruction and does not allow stack unwinding to propagate
836 through it.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]837
Duncan Sands4ee46812007-07-27 19:57:41 +0000[diff] [blame]838 <dt><tt>nest</tt></dt>
839 <dd>This indicates that the parameter can be excised using the
840 <a href="#int_trampoline">trampoline intrinsics</a>.</dd>
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]841 <dt><tt>readonly</tt></dt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]842 <dd>This function attribute indicates that the function has no side-effects
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]843 except for producing a return value or throwing an exception. The value
844 returned must only depend on the function arguments and/or global variables.
845 It may use values obtained by dereferencing pointers.</dd>
846 <dt><tt>readnone</tt></dt>
847 <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]848 function, but in addition it is not allowed to dereference any pointer arguments
849 or global variables.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]850 </dl>
851
852</div>
853
854<!-- ======================================================================= -->
855<div class="doc_subsection">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]856 <a name="gc">Garbage Collector Names</a>
857</div>
858
859<div class="doc_text">
860<p>Each function may specify a garbage collector name, which is simply a
861string.</p>
862
863<div class="doc_code"><pre
864>define void @f() gc "name" { ...</pre></div>
865
866<p>The compiler declares the supported values of <i>name</i>. Specifying a
867collector which will cause the compiler to alter its output in order to support
868the named garbage collection algorithm.</p>
869</div>
870
871<!-- ======================================================================= -->
872<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]873 <a name="moduleasm">Module-Level Inline Assembly</a>
874</div>
875
876<div class="doc_text">
877<p>
878Modules may contain "module-level inline asm" blocks, which corresponds to the
879GCC "file scope inline asm" blocks. These blocks are internally concatenated by
880LLVM and treated as a single unit, but may be separated in the .ll file if
881desired. The syntax is very simple:
882</p>
883
884<div class="doc_code">
885<pre>
886module asm "inline asm code goes here"
887module asm "more can go here"
888</pre>
889</div>
890
891<p>The strings can contain any character by escaping non-printable characters.
892 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
893 for the number.
894</p>
895
896<p>
897 The inline asm code is simply printed to the machine code .s file when
898 assembly code is generated.
899</p>
900</div>
901
902<!-- ======================================================================= -->
903<div class="doc_subsection">
904 <a name="datalayout">Data Layout</a>
905</div>
906
907<div class="doc_text">
908<p>A module may specify a target specific data layout string that specifies how
909data is to be laid out in memory. The syntax for the data layout is simply:</p>
910<pre> target datalayout = "<i>layout specification</i>"</pre>
911<p>The <i>layout specification</i> consists of a list of specifications
912separated by the minus sign character ('-'). Each specification starts with a
913letter and may include other information after the letter to define some
914aspect of the data layout. The specifications accepted are as follows: </p>
915<dl>
916 <dt><tt>E</tt></dt>
917 <dd>Specifies that the target lays out data in big-endian form. That is, the
918 bits with the most significance have the lowest address location.</dd>
919 <dt><tt>e</tt></dt>
920 <dd>Specifies that hte target lays out data in little-endian form. That is,
921 the bits with the least significance have the lowest address location.</dd>
922 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
923 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
924 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
925 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
926 too.</dd>
927 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
928 <dd>This specifies the alignment for an integer type of a given bit
929 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
930 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
931 <dd>This specifies the alignment for a vector type of a given bit
932 <i>size</i>.</dd>
933 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
934 <dd>This specifies the alignment for a floating point type of a given bit
935 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
936 (double).</dd>
937 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
938 <dd>This specifies the alignment for an aggregate type of a given bit
939 <i>size</i>.</dd>
940</dl>
941<p>When constructing the data layout for a given target, LLVM starts with a
942default set of specifications which are then (possibly) overriden by the
943specifications in the <tt>datalayout</tt> keyword. The default specifications
944are given in this list:</p>
945<ul>
946 <li><tt>E</tt> - big endian</li>
947 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
948 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
949 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
950 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
951 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
952 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
953 alignment of 64-bits</li>
954 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
955 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
956 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
957 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
958 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
959</ul>
960<p>When llvm is determining the alignment for a given type, it uses the
961following rules:
962<ol>
963 <li>If the type sought is an exact match for one of the specifications, that
964 specification is used.</li>
965 <li>If no match is found, and the type sought is an integer type, then the
966 smallest integer type that is larger than the bitwidth of the sought type is
967 used. If none of the specifications are larger than the bitwidth then the the
968 largest integer type is used. For example, given the default specifications
969 above, the i7 type will use the alignment of i8 (next largest) while both
970 i65 and i256 will use the alignment of i64 (largest specified).</li>
971 <li>If no match is found, and the type sought is a vector type, then the
972 largest vector type that is smaller than the sought vector type will be used
973 as a fall back. This happens because <128 x double> can be implemented in
974 terms of 64 <2 x double>, for example.</li>
975</ol>
976</div>
977
978<!-- *********************************************************************** -->
979<div class="doc_section"> <a name="typesystem">Type System</a> </div>
980<!-- *********************************************************************** -->
981
982<div class="doc_text">
983
984<p>The LLVM type system is one of the most important features of the
985intermediate representation. Being typed enables a number of
986optimizations to be performed on the IR directly, without having to do
987extra analyses on the side before the transformation. A strong type
988system makes it easier to read the generated code and enables novel
989analyses and transformations that are not feasible to perform on normal
990three address code representations.</p>
991
992</div>
993
994<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]995<div class="doc_subsection"> <a name="t_classifications">Type
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]996Classifications</a> </div>
997<div class="doc_text">
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]998<p>The types fall into a few useful
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]999classifications:</p>
1000
1001<table border="1" cellspacing="0" cellpadding="4">
1002 <tbody>
1003 <tr><th>Classification</th><th>Types</th></tr>
1004 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1005 <td><a href="#t_integer">integer</a></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1006 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1007 </tr>
1008 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1009 <td><a href="#t_floating">floating point</a></td>
1010 <td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1011 </tr>
1012 <tr>
1013 <td><a name="t_firstclass">first class</a></td>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1014 <td><a href="#t_integer">integer</a>,
1015 <a href="#t_floating">floating point</a>,
1016 <a href="#t_pointer">pointer</a>,
1017 <a href="#t_vector">vector</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1018 </td>
1019 </tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1020 <tr>
1021 <td><a href="#t_primitive">primitive</a></td>
1022 <td><a href="#t_label">label</a>,
1023 <a href="#t_void">void</a>,
1024 <a href="#t_integer">integer</a>,
1025 <a href="#t_floating">floating point</a>.</td>
1026 </tr>
1027 <tr>
1028 <td><a href="#t_derived">derived</a></td>
1029 <td><a href="#t_integer">integer</a>,
1030 <a href="#t_array">array</a>,
1031 <a href="#t_function">function</a>,
1032 <a href="#t_pointer">pointer</a>,
1033 <a href="#t_struct">structure</a>,
1034 <a href="#t_pstruct">packed structure</a>,
1035 <a href="#t_vector">vector</a>,
1036 <a href="#t_opaque">opaque</a>.
1037 </tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1038 </tbody>
1039</table>
1040
1041<p>The <a href="#t_firstclass">first class</a> types are perhaps the
1042most important. Values of these types are the only ones which can be
1043produced by instructions, passed as arguments, or used as operands to
1044instructions. This means that all structures and arrays must be
1045manipulated either by pointer or by component.</p>
1046</div>
1047
1048<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1049<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1050
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1051<div class="doc_text">
1052<p>The primitive types are the fundamental building blocks of the LLVM
1053system.</p>
1054
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1055</div>
1056
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1057<!-- _______________________________________________________________________ -->
1058<div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
1059
1060<div class="doc_text">
1061 <table>
1062 <tbody>
1063 <tr><th>Type</th><th>Description</th></tr>
1064 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
1065 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
1066 <tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
1067 <tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
1068 <tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
1069 </tbody>
1070 </table>
1071</div>
1072
1073<!-- _______________________________________________________________________ -->
1074<div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
1075
1076<div class="doc_text">
1077<h5>Overview:</h5>
1078<p>The void type does not represent any value and has no size.</p>
1079
1080<h5>Syntax:</h5>
1081
1082<pre>
1083 void
1084</pre>
1085</div>
1086
1087<!-- _______________________________________________________________________ -->
1088<div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
1089
1090<div class="doc_text">
1091<h5>Overview:</h5>
1092<p>The label type represents code labels.</p>
1093
1094<h5>Syntax:</h5>
1095
1096<pre>
1097 label
1098</pre>
1099</div>
1100
1101
1102<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1103<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1104
1105<div class="doc_text">
1106
1107<p>The real power in LLVM comes from the derived types in the system.
1108This is what allows a programmer to represent arrays, functions,
1109pointers, and other useful types. Note that these derived types may be
1110recursive: For example, it is possible to have a two dimensional array.</p>
1111
1112</div>
1113
1114<!-- _______________________________________________________________________ -->
1115<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1116
1117<div class="doc_text">
1118
1119<h5>Overview:</h5>
1120<p>The integer type is a very simple derived type that simply specifies an
1121arbitrary bit width for the integer type desired. Any bit width from 1 bit to
11222^23-1 (about 8 million) can be specified.</p>
1123
1124<h5>Syntax:</h5>
1125
1126<pre>
1127 iN
1128</pre>
1129
1130<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1131value.</p>
1132
1133<h5>Examples:</h5>
1134<table class="layout">
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]1135 <tbody>
1136 <tr>
1137 <td><tt>i1</tt></td>
1138 <td>a single-bit integer.</td>
1139 </tr><tr>
1140 <td><tt>i32</tt></td>
1141 <td>a 32-bit integer.</td>
1142 </tr><tr>
1143 <td><tt>i1942652</tt></td>
1144 <td>a really big integer of over 1 million bits.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1145 </tr>
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]1146 </tbody>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1147</table>
1148</div>
1149
1150<!-- _______________________________________________________________________ -->
1151<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1152
1153<div class="doc_text">
1154
1155<h5>Overview:</h5>
1156
1157<p>The array type is a very simple derived type that arranges elements
1158sequentially in memory. The array type requires a size (number of
1159elements) and an underlying data type.</p>
1160
1161<h5>Syntax:</h5>
1162
1163<pre>
1164 [&lt;# elements&gt; x &lt;elementtype&gt;]
1165</pre>
1166
1167<p>The number of elements is a constant integer value; elementtype may
1168be any type with a size.</p>
1169
1170<h5>Examples:</h5>
1171<table class="layout">
1172 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1173 <td class="left"><tt>[40 x i32]</tt></td>
1174 <td class="left">Array of 40 32-bit integer values.</td>
1175 </tr>
1176 <tr class="layout">
1177 <td class="left"><tt>[41 x i32]</tt></td>
1178 <td class="left">Array of 41 32-bit integer values.</td>
1179 </tr>
1180 <tr class="layout">
1181 <td class="left"><tt>[4 x i8]</tt></td>
1182 <td class="left">Array of 4 8-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1183 </tr>
1184</table>
1185<p>Here are some examples of multidimensional arrays:</p>
1186<table class="layout">
1187 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1188 <td class="left"><tt>[3 x [4 x i32]]</tt></td>
1189 <td class="left">3x4 array of 32-bit integer values.</td>
1190 </tr>
1191 <tr class="layout">
1192 <td class="left"><tt>[12 x [10 x float]]</tt></td>
1193 <td class="left">12x10 array of single precision floating point values.</td>
1194 </tr>
1195 <tr class="layout">
1196 <td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
1197 <td class="left">2x3x4 array of 16-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1198 </tr>
1199</table>
1200
1201<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1202length array. Normally, accesses past the end of an array are undefined in
1203LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1204As a special case, however, zero length arrays are recognized to be variable
1205length. This allows implementation of 'pascal style arrays' with the LLVM
1206type "{ i32, [0 x float]}", for example.</p>
1207
1208</div>
1209
1210<!-- _______________________________________________________________________ -->
1211<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1212<div class="doc_text">
1213<h5>Overview:</h5>
1214<p>The function type can be thought of as a function signature. It
1215consists of a return type and a list of formal parameter types.
1216Function types are usually used to build virtual function tables
1217(which are structures of pointers to functions), for indirect function
1218calls, and when defining a function.</p>
1219<p>
1220The return type of a function type cannot be an aggregate type.
1221</p>
1222<h5>Syntax:</h5>
1223<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
1224<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
1225specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1226which indicates that the function takes a variable number of arguments.
1227Variable argument functions can access their arguments with the <a
1228 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
1229<h5>Examples:</h5>
1230<table class="layout">
1231 <tr class="layout">
1232 <td class="left"><tt>i32 (i32)</tt></td>
1233 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1234 </td>
1235 </tr><tr class="layout">
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]1236 <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1237 </tt></td>
1238 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1239 an <tt>i16</tt> that should be sign extended and a
1240 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1241 <tt>float</tt>.
1242 </td>
1243 </tr><tr class="layout">
1244 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1245 <td class="left">A vararg function that takes at least one
1246 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1247 which returns an integer. This is the signature for <tt>printf</tt> in
1248 LLVM.
1249 </td>
1250 </tr>
1251</table>
1252
1253</div>
1254<!-- _______________________________________________________________________ -->
1255<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1256<div class="doc_text">
1257<h5>Overview:</h5>
1258<p>The structure type is used to represent a collection of data members
1259together in memory. The packing of the field types is defined to match
1260the ABI of the underlying processor. The elements of a structure may
1261be any type that has a size.</p>
1262<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1263and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1264field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1265instruction.</p>
1266<h5>Syntax:</h5>
1267<pre> { &lt;type list&gt; }<br></pre>
1268<h5>Examples:</h5>
1269<table class="layout">
1270 <tr class="layout">
1271 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1272 <td class="left">A triple of three <tt>i32</tt> values</td>
1273 </tr><tr class="layout">
1274 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1275 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1276 second element is a <a href="#t_pointer">pointer</a> to a
1277 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1278 an <tt>i32</tt>.</td>
1279 </tr>
1280</table>
1281</div>
1282
1283<!-- _______________________________________________________________________ -->
1284<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1285</div>
1286<div class="doc_text">
1287<h5>Overview:</h5>
1288<p>The packed structure type is used to represent a collection of data members
1289together in memory. There is no padding between fields. Further, the alignment
1290of a packed structure is 1 byte. The elements of a packed structure may
1291be any type that has a size.</p>
1292<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1293and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1294field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1295instruction.</p>
1296<h5>Syntax:</h5>
1297<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1298<h5>Examples:</h5>
1299<table class="layout">
1300 <tr class="layout">
1301 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1302 <td class="left">A triple of three <tt>i32</tt> values</td>
1303 </tr><tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1304 <td class="left"><tt>&lt; { float, i32 (i32)* } &gt;</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1305 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1306 second element is a <a href="#t_pointer">pointer</a> to a
1307 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1308 an <tt>i32</tt>.</td>
1309 </tr>
1310</table>
1311</div>
1312
1313<!-- _______________________________________________________________________ -->
1314<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1315<div class="doc_text">
1316<h5>Overview:</h5>
1317<p>As in many languages, the pointer type represents a pointer or
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]1318reference to another object, which must live in memory. Pointer types may have
1319an optional address space attribute defining the target-specific numbered
1320address space where the pointed-to object resides. The default address space is
1321zero.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1322<h5>Syntax:</h5>
1323<pre> &lt;type&gt; *<br></pre>
1324<h5>Examples:</h5>
1325<table class="layout">
1326 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1327 <td class="left"><tt>[4x i32]*</tt></td>
1328 <td class="left">A <a href="#t_pointer">pointer</a> to <a
1329 href="#t_array">array</a> of four <tt>i32</tt> values.</td>
1330 </tr>
1331 <tr class="layout">
1332 <td class="left"><tt>i32 (i32 *) *</tt></td>
1333 <td class="left"> A <a href="#t_pointer">pointer</a> to a <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1334 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1335 <tt>i32</tt>.</td>
1336 </tr>
1337 <tr class="layout">
1338 <td class="left"><tt>i32 addrspace(5)*</tt></td>
1339 <td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
1340 that resides in address space #5.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1341 </tr>
1342</table>
1343</div>
1344
1345<!-- _______________________________________________________________________ -->
1346<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1347<div class="doc_text">
1348
1349<h5>Overview:</h5>
1350
1351<p>A vector type is a simple derived type that represents a vector
1352of elements. Vector types are used when multiple primitive data
1353are operated in parallel using a single instruction (SIMD).
1354A vector type requires a size (number of
1355elements) and an underlying primitive data type. Vectors must have a power
1356of two length (1, 2, 4, 8, 16 ...). Vector types are
1357considered <a href="#t_firstclass">first class</a>.</p>
1358
1359<h5>Syntax:</h5>
1360
1361<pre>
1362 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1363</pre>
1364
1365<p>The number of elements is a constant integer value; elementtype may
1366be any integer or floating point type.</p>
1367
1368<h5>Examples:</h5>
1369
1370<table class="layout">
1371 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1372 <td class="left"><tt>&lt;4 x i32&gt;</tt></td>
1373 <td class="left">Vector of 4 32-bit integer values.</td>
1374 </tr>
1375 <tr class="layout">
1376 <td class="left"><tt>&lt;8 x float&gt;</tt></td>
1377 <td class="left">Vector of 8 32-bit floating-point values.</td>
1378 </tr>
1379 <tr class="layout">
1380 <td class="left"><tt>&lt;2 x i64&gt;</tt></td>
1381 <td class="left">Vector of 2 64-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1382 </tr>
1383</table>
1384</div>
1385
1386<!-- _______________________________________________________________________ -->
1387<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1388<div class="doc_text">
1389
1390<h5>Overview:</h5>
1391
1392<p>Opaque types are used to represent unknown types in the system. This
Gordon Henriksenda0706e2007-10-14 00:34:53 +0000[diff] [blame]1393corresponds (for example) to the C notion of a forward declared structure type.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1394In LLVM, opaque types can eventually be resolved to any type (not just a
1395structure type).</p>
1396
1397<h5>Syntax:</h5>
1398
1399<pre>
1400 opaque
1401</pre>
1402
1403<h5>Examples:</h5>
1404
1405<table class="layout">
1406 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1407 <td class="left"><tt>opaque</tt></td>
1408 <td class="left">An opaque type.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1409 </tr>
1410</table>
1411</div>
1412
1413
1414<!-- *********************************************************************** -->
1415<div class="doc_section"> <a name="constants">Constants</a> </div>
1416<!-- *********************************************************************** -->
1417
1418<div class="doc_text">
1419
1420<p>LLVM has several different basic types of constants. This section describes
1421them all and their syntax.</p>
1422
1423</div>
1424
1425<!-- ======================================================================= -->
1426<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1427
1428<div class="doc_text">
1429
1430<dl>
1431 <dt><b>Boolean constants</b></dt>
1432
1433 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1434 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1435 </dd>
1436
1437 <dt><b>Integer constants</b></dt>
1438
1439 <dd>Standard integers (such as '4') are constants of the <a
1440 href="#t_integer">integer</a> type. Negative numbers may be used with
1441 integer types.
1442 </dd>
1443
1444 <dt><b>Floating point constants</b></dt>
1445
1446 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1447 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
1448 notation (see below). Floating point constants must have a <a
1449 href="#t_floating">floating point</a> type. </dd>
1450
1451 <dt><b>Null pointer constants</b></dt>
1452
1453 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1454 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1455
1456</dl>
1457
1458<p>The one non-intuitive notation for constants is the optional hexadecimal form
1459of floating point constants. For example, the form '<tt>double
14600x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
14614.5e+15</tt>'. The only time hexadecimal floating point constants are required
1462(and the only time that they are generated by the disassembler) is when a
1463floating point constant must be emitted but it cannot be represented as a
1464decimal floating point number. For example, NaN's, infinities, and other
1465special values are represented in their IEEE hexadecimal format so that
1466assembly and disassembly do not cause any bits to change in the constants.</p>
1467
1468</div>
1469
1470<!-- ======================================================================= -->
1471<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1472</div>
1473
1474<div class="doc_text">
1475<p>Aggregate constants arise from aggregation of simple constants
1476and smaller aggregate constants.</p>
1477
1478<dl>
1479 <dt><b>Structure constants</b></dt>
1480
1481 <dd>Structure constants are represented with notation similar to structure
1482 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner6c8de962007-12-25 20:34:52 +0000[diff] [blame]1483 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
1484 where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1485 must have <a href="#t_struct">structure type</a>, and the number and
1486 types of elements must match those specified by the type.
1487 </dd>
1488
1489 <dt><b>Array constants</b></dt>
1490
1491 <dd>Array constants are represented with notation similar to array type
1492 definitions (a comma separated list of elements, surrounded by square brackets
1493 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1494 constants must have <a href="#t_array">array type</a>, and the number and
1495 types of elements must match those specified by the type.
1496 </dd>
1497
1498 <dt><b>Vector constants</b></dt>
1499
1500 <dd>Vector constants are represented with notation similar to vector type
1501 definitions (a comma separated list of elements, surrounded by
1502 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1503 i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must have <a
1504 href="#t_vector">vector type</a>, and the number and types of elements must
1505 match those specified by the type.
1506 </dd>
1507
1508 <dt><b>Zero initialization</b></dt>
1509
1510 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1511 value to zero of <em>any</em> type, including scalar and aggregate types.
1512 This is often used to avoid having to print large zero initializers (e.g. for
1513 large arrays) and is always exactly equivalent to using explicit zero
1514 initializers.
1515 </dd>
1516</dl>
1517
1518</div>
1519
1520<!-- ======================================================================= -->
1521<div class="doc_subsection">
1522 <a name="globalconstants">Global Variable and Function Addresses</a>
1523</div>
1524
1525<div class="doc_text">
1526
1527<p>The addresses of <a href="#globalvars">global variables</a> and <a
1528href="#functionstructure">functions</a> are always implicitly valid (link-time)
1529constants. These constants are explicitly referenced when the <a
1530href="#identifiers">identifier for the global</a> is used and always have <a
1531href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1532file:</p>
1533
1534<div class="doc_code">
1535<pre>
1536@X = global i32 17
1537@Y = global i32 42
1538@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1539</pre>
1540</div>
1541
1542</div>
1543
1544<!-- ======================================================================= -->
1545<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1546<div class="doc_text">
1547 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1548 no specific value. Undefined values may be of any type and be used anywhere
1549 a constant is permitted.</p>
1550
1551 <p>Undefined values indicate to the compiler that the program is well defined
1552 no matter what value is used, giving the compiler more freedom to optimize.
1553 </p>
1554</div>
1555
1556<!-- ======================================================================= -->
1557<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1558</div>
1559
1560<div class="doc_text">
1561
1562<p>Constant expressions are used to allow expressions involving other constants
1563to be used as constants. Constant expressions may be of any <a
1564href="#t_firstclass">first class</a> type and may involve any LLVM operation
1565that does not have side effects (e.g. load and call are not supported). The
1566following is the syntax for constant expressions:</p>
1567
1568<dl>
1569 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1570 <dd>Truncate a constant to another type. The bit size of CST must be larger
1571 than the bit size of TYPE. Both types must be integers.</dd>
1572
1573 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1574 <dd>Zero extend a constant to another type. The bit size of CST must be
1575 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1576
1577 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1578 <dd>Sign extend a constant to another type. The bit size of CST must be
1579 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1580
1581 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1582 <dd>Truncate a floating point constant to another floating point type. The
1583 size of CST must be larger than the size of TYPE. Both types must be
1584 floating point.</dd>
1585
1586 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1587 <dd>Floating point extend a constant to another type. The size of CST must be
1588 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1589
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]1590 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1591 <dd>Convert a floating point constant to the corresponding unsigned integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1592 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1593 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1594 of the same number of elements. If the value won't fit in the integer type,
1595 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1596
1597 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1598 <dd>Convert a floating point constant to the corresponding signed integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1599 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1600 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1601 of the same number of elements. If the value won't fit in the integer type,
1602 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1603
1604 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1605 <dd>Convert an unsigned integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1606 constant. TYPE must be a scalar or vector floating point type. CST must be of
1607 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1608 of the same number of elements. If the value won't fit in the floating point
1609 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1610
1611 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
1612 <dd>Convert a signed integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1613 constant. TYPE must be a scalar or vector floating point type. CST must be of
1614 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1615 of the same number of elements. If the value won't fit in the floating point
1616 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1617
1618 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1619 <dd>Convert a pointer typed constant to the corresponding integer constant
1620 TYPE must be an integer type. CST must be of pointer type. The CST value is
1621 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1622
1623 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1624 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1625 pointer type. CST must be of integer type. The CST value is zero extended,
1626 truncated, or unchanged to make it fit in a pointer size. This one is
1627 <i>really</i> dangerous!</dd>
1628
1629 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
1630 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1631 identical (same number of bits). The conversion is done as if the CST value
1632 was stored to memory and read back as TYPE. In other words, no bits change
1633 with this operator, just the type. This can be used for conversion of
1634 vector types to any other type, as long as they have the same bit width. For
1635 pointers it is only valid to cast to another pointer type.
1636 </dd>
1637
1638 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1639
1640 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1641 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1642 instruction, the index list may have zero or more indexes, which are required
1643 to make sense for the type of "CSTPTR".</dd>
1644
1645 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1646
1647 <dd>Perform the <a href="#i_select">select operation</a> on
1648 constants.</dd>
1649
1650 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1651 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1652
1653 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1654 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
1655
1656 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1657
1658 <dd>Perform the <a href="#i_extractelement">extractelement
1659 operation</a> on constants.
1660
1661 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1662
1663 <dd>Perform the <a href="#i_insertelement">insertelement
1664 operation</a> on constants.</dd>
1665
1666
1667 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1668
1669 <dd>Perform the <a href="#i_shufflevector">shufflevector
1670 operation</a> on constants.</dd>
1671
1672 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1673
1674 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1675 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
1676 binary</a> operations. The constraints on operands are the same as those for
1677 the corresponding instruction (e.g. no bitwise operations on floating point
1678 values are allowed).</dd>
1679</dl>
1680</div>
1681
1682<!-- *********************************************************************** -->
1683<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1684<!-- *********************************************************************** -->
1685
1686<!-- ======================================================================= -->
1687<div class="doc_subsection">
1688<a name="inlineasm">Inline Assembler Expressions</a>
1689</div>
1690
1691<div class="doc_text">
1692
1693<p>
1694LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1695Module-Level Inline Assembly</a>) through the use of a special value. This
1696value represents the inline assembler as a string (containing the instructions
1697to emit), a list of operand constraints (stored as a string), and a flag that
1698indicates whether or not the inline asm expression has side effects. An example
1699inline assembler expression is:
1700</p>
1701
1702<div class="doc_code">
1703<pre>
1704i32 (i32) asm "bswap $0", "=r,r"
1705</pre>
1706</div>
1707
1708<p>
1709Inline assembler expressions may <b>only</b> be used as the callee operand of
1710a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1711</p>
1712
1713<div class="doc_code">
1714<pre>
1715%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
1716</pre>
1717</div>
1718
1719<p>
1720Inline asms with side effects not visible in the constraint list must be marked
1721as having side effects. This is done through the use of the
1722'<tt>sideeffect</tt>' keyword, like so:
1723</p>
1724
1725<div class="doc_code">
1726<pre>
1727call void asm sideeffect "eieio", ""()
1728</pre>
1729</div>
1730
1731<p>TODO: The format of the asm and constraints string still need to be
1732documented here. Constraints on what can be done (e.g. duplication, moving, etc
1733need to be documented).
1734</p>
1735
1736</div>
1737
1738<!-- *********************************************************************** -->
1739<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1740<!-- *********************************************************************** -->
1741
1742<div class="doc_text">
1743
1744<p>The LLVM instruction set consists of several different
1745classifications of instructions: <a href="#terminators">terminator
1746instructions</a>, <a href="#binaryops">binary instructions</a>,
1747<a href="#bitwiseops">bitwise binary instructions</a>, <a
1748 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1749instructions</a>.</p>
1750
1751</div>
1752
1753<!-- ======================================================================= -->
1754<div class="doc_subsection"> <a name="terminators">Terminator
1755Instructions</a> </div>
1756
1757<div class="doc_text">
1758
1759<p>As mentioned <a href="#functionstructure">previously</a>, every
1760basic block in a program ends with a "Terminator" instruction, which
1761indicates which block should be executed after the current block is
1762finished. These terminator instructions typically yield a '<tt>void</tt>'
1763value: they produce control flow, not values (the one exception being
1764the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
1765<p>There are six different terminator instructions: the '<a
1766 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1767instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
1768the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1769 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1770 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
1771
1772</div>
1773
1774<!-- _______________________________________________________________________ -->
1775<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1776Instruction</a> </div>
1777<div class="doc_text">
1778<h5>Syntax:</h5>
1779<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
1780 ret void <i>; Return from void function</i>
1781</pre>
1782<h5>Overview:</h5>
1783<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1784value) from a function back to the caller.</p>
1785<p>There are two forms of the '<tt>ret</tt>' instruction: one that
1786returns a value and then causes control flow, and one that just causes
1787control flow to occur.</p>
1788<h5>Arguments:</h5>
1789<p>The '<tt>ret</tt>' instruction may return any '<a
1790 href="#t_firstclass">first class</a>' type. Notice that a function is
1791not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1792instruction inside of the function that returns a value that does not
1793match the return type of the function.</p>
1794<h5>Semantics:</h5>
1795<p>When the '<tt>ret</tt>' instruction is executed, control flow
1796returns back to the calling function's context. If the caller is a "<a
1797 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
1798the instruction after the call. If the caller was an "<a
1799 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1800at the beginning of the "normal" destination block. If the instruction
1801returns a value, that value shall set the call or invoke instruction's
1802return value.</p>
1803<h5>Example:</h5>
1804<pre> ret i32 5 <i>; Return an integer value of 5</i>
1805 ret void <i>; Return from a void function</i>
1806</pre>
1807</div>
1808<!-- _______________________________________________________________________ -->
1809<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
1810<div class="doc_text">
1811<h5>Syntax:</h5>
1812<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
1813</pre>
1814<h5>Overview:</h5>
1815<p>The '<tt>br</tt>' instruction is used to cause control flow to
1816transfer to a different basic block in the current function. There are
1817two forms of this instruction, corresponding to a conditional branch
1818and an unconditional branch.</p>
1819<h5>Arguments:</h5>
1820<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1821single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
1822unconditional form of the '<tt>br</tt>' instruction takes a single
1823'<tt>label</tt>' value as a target.</p>
1824<h5>Semantics:</h5>
1825<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
1826argument is evaluated. If the value is <tt>true</tt>, control flows
1827to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1828control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
1829<h5>Example:</h5>
1830<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
1831 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
1832</div>
1833<!-- _______________________________________________________________________ -->
1834<div class="doc_subsubsection">
1835 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1836</div>
1837
1838<div class="doc_text">
1839<h5>Syntax:</h5>
1840
1841<pre>
1842 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1843</pre>
1844
1845<h5>Overview:</h5>
1846
1847<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1848several different places. It is a generalization of the '<tt>br</tt>'
1849instruction, allowing a branch to occur to one of many possible
1850destinations.</p>
1851
1852
1853<h5>Arguments:</h5>
1854
1855<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1856comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1857an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1858table is not allowed to contain duplicate constant entries.</p>
1859
1860<h5>Semantics:</h5>
1861
1862<p>The <tt>switch</tt> instruction specifies a table of values and
1863destinations. When the '<tt>switch</tt>' instruction is executed, this
1864table is searched for the given value. If the value is found, control flow is
1865transfered to the corresponding destination; otherwise, control flow is
1866transfered to the default destination.</p>
1867
1868<h5>Implementation:</h5>
1869
1870<p>Depending on properties of the target machine and the particular
1871<tt>switch</tt> instruction, this instruction may be code generated in different
1872ways. For example, it could be generated as a series of chained conditional
1873branches or with a lookup table.</p>
1874
1875<h5>Example:</h5>
1876
1877<pre>
1878 <i>; Emulate a conditional br instruction</i>
1879 %Val = <a href="#i_zext">zext</a> i1 %value to i32
1880 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
1881
1882 <i>; Emulate an unconditional br instruction</i>
1883 switch i32 0, label %dest [ ]
1884
1885 <i>; Implement a jump table:</i>
1886 switch i32 %val, label %otherwise [ i32 0, label %onzero
1887 i32 1, label %onone
1888 i32 2, label %ontwo ]
1889</pre>
1890</div>
1891
1892<!-- _______________________________________________________________________ -->
1893<div class="doc_subsubsection">
1894 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1895</div>
1896
1897<div class="doc_text">
1898
1899<h5>Syntax:</h5>
1900
1901<pre>
1902 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1903 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
1904</pre>
1905
1906<h5>Overview:</h5>
1907
1908<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1909function, with the possibility of control flow transfer to either the
1910'<tt>normal</tt>' label or the
1911'<tt>exception</tt>' label. If the callee function returns with the
1912"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1913"normal" label. If the callee (or any indirect callees) returns with the "<a
1914href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1915continued at the dynamically nearest "exception" label.</p>
1916
1917<h5>Arguments:</h5>
1918
1919<p>This instruction requires several arguments:</p>
1920
1921<ol>
1922 <li>
1923 The optional "cconv" marker indicates which <a href="#callingconv">calling
1924 convention</a> the call should use. If none is specified, the call defaults
1925 to using C calling conventions.
1926 </li>
1927 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1928 function value being invoked. In most cases, this is a direct function
1929 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1930 an arbitrary pointer to function value.
1931 </li>
1932
1933 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1934 function to be invoked. </li>
1935
1936 <li>'<tt>function args</tt>': argument list whose types match the function
1937 signature argument types. If the function signature indicates the function
1938 accepts a variable number of arguments, the extra arguments can be
1939 specified. </li>
1940
1941 <li>'<tt>normal label</tt>': the label reached when the called function
1942 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1943
1944 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1945 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1946
1947</ol>
1948
1949<h5>Semantics:</h5>
1950
1951<p>This instruction is designed to operate as a standard '<tt><a
1952href="#i_call">call</a></tt>' instruction in most regards. The primary
1953difference is that it establishes an association with a label, which is used by
1954the runtime library to unwind the stack.</p>
1955
1956<p>This instruction is used in languages with destructors to ensure that proper
1957cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1958exception. Additionally, this is important for implementation of
1959'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1960
1961<h5>Example:</h5>
1962<pre>
1963 %retval = invoke i32 %Test(i32 15) to label %Continue
1964 unwind label %TestCleanup <i>; {i32}:retval set</i>
1965 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1966 unwind label %TestCleanup <i>; {i32}:retval set</i>
1967</pre>
1968</div>
1969
1970
1971<!-- _______________________________________________________________________ -->
1972
1973<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1974Instruction</a> </div>
1975
1976<div class="doc_text">
1977
1978<h5>Syntax:</h5>
1979<pre>
1980 unwind
1981</pre>
1982
1983<h5>Overview:</h5>
1984
1985<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1986at the first callee in the dynamic call stack which used an <a
1987href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1988primarily used to implement exception handling.</p>
1989
1990<h5>Semantics:</h5>
1991
1992<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1993immediately halt. The dynamic call stack is then searched for the first <a
1994href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1995execution continues at the "exceptional" destination block specified by the
1996<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1997dynamic call chain, undefined behavior results.</p>
1998</div>
1999
2000<!-- _______________________________________________________________________ -->
2001
2002<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
2003Instruction</a> </div>
2004
2005<div class="doc_text">
2006
2007<h5>Syntax:</h5>
2008<pre>
2009 unreachable
2010</pre>
2011
2012<h5>Overview:</h5>
2013
2014<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
2015instruction is used to inform the optimizer that a particular portion of the
2016code is not reachable. This can be used to indicate that the code after a
2017no-return function cannot be reached, and other facts.</p>
2018
2019<h5>Semantics:</h5>
2020
2021<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
2022</div>
2023
2024
2025
2026<!-- ======================================================================= -->
2027<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
2028<div class="doc_text">
2029<p>Binary operators are used to do most of the computation in a
2030program. They require two operands, execute an operation on them, and
2031produce a single value. The operands might represent
2032multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
2033The result value of a binary operator is not
2034necessarily the same type as its operands.</p>
2035<p>There are several different binary operators:</p>
2036</div>
2037<!-- _______________________________________________________________________ -->
2038<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
2039Instruction</a> </div>
2040<div class="doc_text">
2041<h5>Syntax:</h5>
2042<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2043</pre>
2044<h5>Overview:</h5>
2045<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
2046<h5>Arguments:</h5>
2047<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
2048 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
2049 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2050Both arguments must have identical types.</p>
2051<h5>Semantics:</h5>
2052<p>The value produced is the integer or floating point sum of the two
2053operands.</p>
2054<h5>Example:</h5>
2055<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
2056</pre>
2057</div>
2058<!-- _______________________________________________________________________ -->
2059<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
2060Instruction</a> </div>
2061<div class="doc_text">
2062<h5>Syntax:</h5>
2063<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2064</pre>
2065<h5>Overview:</h5>
2066<p>The '<tt>sub</tt>' instruction returns the difference of its two
2067operands.</p>
2068<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
2069instruction present in most other intermediate representations.</p>
2070<h5>Arguments:</h5>
2071<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
2072 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2073values.
2074This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2075Both arguments must have identical types.</p>
2076<h5>Semantics:</h5>
2077<p>The value produced is the integer or floating point difference of
2078the two operands.</p>
2079<h5>Example:</h5>
2080<pre>
2081 &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2082 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2083</pre>
2084</div>
2085<!-- _______________________________________________________________________ -->
2086<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
2087Instruction</a> </div>
2088<div class="doc_text">
2089<h5>Syntax:</h5>
2090<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2091</pre>
2092<h5>Overview:</h5>
2093<p>The '<tt>mul</tt>' instruction returns the product of its two
2094operands.</p>
2095<h5>Arguments:</h5>
2096<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
2097 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2098values.
2099This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2100Both arguments must have identical types.</p>
2101<h5>Semantics:</h5>
2102<p>The value produced is the integer or floating point product of the
2103two operands.</p>
2104<p>Because the operands are the same width, the result of an integer
2105multiplication is the same whether the operands should be deemed unsigned or
2106signed.</p>
2107<h5>Example:</h5>
2108<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2109</pre>
2110</div>
2111<!-- _______________________________________________________________________ -->
2112<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2113</a></div>
2114<div class="doc_text">
2115<h5>Syntax:</h5>
2116<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2117</pre>
2118<h5>Overview:</h5>
2119<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2120operands.</p>
2121<h5>Arguments:</h5>
2122<p>The two arguments to the '<tt>udiv</tt>' instruction must be
2123<a href="#t_integer">integer</a> values. Both arguments must have identical
2124types. This instruction can also take <a href="#t_vector">vector</a> versions
2125of the values in which case the elements must be integers.</p>
2126<h5>Semantics:</h5>
2127<p>The value produced is the unsigned integer quotient of the two operands. This
2128instruction always performs an unsigned division operation, regardless of
2129whether the arguments are unsigned or not.</p>
2130<h5>Example:</h5>
2131<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2132</pre>
2133</div>
2134<!-- _______________________________________________________________________ -->
2135<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2136</a> </div>
2137<div class="doc_text">
2138<h5>Syntax:</h5>
2139<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2140</pre>
2141<h5>Overview:</h5>
2142<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2143operands.</p>
2144<h5>Arguments:</h5>
2145<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2146<a href="#t_integer">integer</a> values. Both arguments must have identical
2147types. This instruction can also take <a href="#t_vector">vector</a> versions
2148of the values in which case the elements must be integers.</p>
2149<h5>Semantics:</h5>
2150<p>The value produced is the signed integer quotient of the two operands. This
2151instruction always performs a signed division operation, regardless of whether
2152the arguments are signed or not.</p>
2153<h5>Example:</h5>
2154<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2155</pre>
2156</div>
2157<!-- _______________________________________________________________________ -->
2158<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2159Instruction</a> </div>
2160<div class="doc_text">
2161<h5>Syntax:</h5>
2162<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2163</pre>
2164<h5>Overview:</h5>
2165<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2166operands.</p>
2167<h5>Arguments:</h5>
2168<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2169<a href="#t_floating">floating point</a> values. Both arguments must have
2170identical types. This instruction can also take <a href="#t_vector">vector</a>
2171versions of floating point values.</p>
2172<h5>Semantics:</h5>
2173<p>The value produced is the floating point quotient of the two operands.</p>
2174<h5>Example:</h5>
2175<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2176</pre>
2177</div>
2178<!-- _______________________________________________________________________ -->
2179<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2180</div>
2181<div class="doc_text">
2182<h5>Syntax:</h5>
2183<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2184</pre>
2185<h5>Overview:</h5>
2186<p>The '<tt>urem</tt>' instruction returns the remainder from the
2187unsigned division of its two arguments.</p>
2188<h5>Arguments:</h5>
2189<p>The two arguments to the '<tt>urem</tt>' instruction must be
2190<a href="#t_integer">integer</a> values. Both arguments must have identical
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2191types. This instruction can also take <a href="#t_vector">vector</a> versions
2192of the values in which case the elements must be integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2193<h5>Semantics:</h5>
2194<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
2195This instruction always performs an unsigned division to get the remainder,
2196regardless of whether the arguments are unsigned or not.</p>
2197<h5>Example:</h5>
2198<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2199</pre>
2200
2201</div>
2202<!-- _______________________________________________________________________ -->
2203<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
2204Instruction</a> </div>
2205<div class="doc_text">
2206<h5>Syntax:</h5>
2207<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2208</pre>
2209<h5>Overview:</h5>
2210<p>The '<tt>srem</tt>' instruction returns the remainder from the
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2211signed division of its two operands. This instruction can also take
2212<a href="#t_vector">vector</a> versions of the values in which case
2213the elements must be integers.</p>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]2214
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2215<h5>Arguments:</h5>
2216<p>The two arguments to the '<tt>srem</tt>' instruction must be
2217<a href="#t_integer">integer</a> values. Both arguments must have identical
2218types.</p>
2219<h5>Semantics:</h5>
2220<p>This instruction returns the <i>remainder</i> of a division (where the result
2221has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2222operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2223a value. For more information about the difference, see <a
2224 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2225Math Forum</a>. For a table of how this is implemented in various languages,
2226please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2227Wikipedia: modulo operation</a>.</p>
2228<h5>Example:</h5>
2229<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2230</pre>
2231
2232</div>
2233<!-- _______________________________________________________________________ -->
2234<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2235Instruction</a> </div>
2236<div class="doc_text">
2237<h5>Syntax:</h5>
2238<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2239</pre>
2240<h5>Overview:</h5>
2241<p>The '<tt>frem</tt>' instruction returns the remainder from the
2242division of its two operands.</p>
2243<h5>Arguments:</h5>
2244<p>The two arguments to the '<tt>frem</tt>' instruction must be
2245<a href="#t_floating">floating point</a> values. Both arguments must have
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2246identical types. This instruction can also take <a href="#t_vector">vector</a>
2247versions of floating point values.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2248<h5>Semantics:</h5>
2249<p>This instruction returns the <i>remainder</i> of a division.</p>
2250<h5>Example:</h5>
2251<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2252</pre>
2253</div>
2254
2255<!-- ======================================================================= -->
2256<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2257Operations</a> </div>
2258<div class="doc_text">
2259<p>Bitwise binary operators are used to do various forms of
2260bit-twiddling in a program. They are generally very efficient
2261instructions and can commonly be strength reduced from other
2262instructions. They require two operands, execute an operation on them,
2263and produce a single value. The resulting value of the bitwise binary
2264operators is always the same type as its first operand.</p>
2265</div>
2266
2267<!-- _______________________________________________________________________ -->
2268<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2269Instruction</a> </div>
2270<div class="doc_text">
2271<h5>Syntax:</h5>
2272<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2273</pre>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2274
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2275<h5>Overview:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2276
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2277<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2278the left a specified number of bits.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2279
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2280<h5>Arguments:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2281
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2282<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2283 href="#t_integer">integer</a> type.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2284
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2285<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2286
2287<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>. If
2288<tt>var2</tt> is (statically or dynamically) equal to or larger than the number
2289of bits in <tt>var1</tt>, the result is undefined.</p>
2290
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2291<h5>Example:</h5><pre>
2292 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2293 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2294 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2295 &lt;result&gt; = shl i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2296</pre>
2297</div>
2298<!-- _______________________________________________________________________ -->
2299<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2300Instruction</a> </div>
2301<div class="doc_text">
2302<h5>Syntax:</h5>
2303<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2304</pre>
2305
2306<h5>Overview:</h5>
2307<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2308operand shifted to the right a specified number of bits with zero fill.</p>
2309
2310<h5>Arguments:</h5>
2311<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2312<a href="#t_integer">integer</a> type.</p>
2313
2314<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2315
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2316<p>This instruction always performs a logical shift right operation. The most
2317significant bits of the result will be filled with zero bits after the
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2318shift. If <tt>var2</tt> is (statically or dynamically) equal to or larger than
2319the number of bits in <tt>var1</tt>, the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2320
2321<h5>Example:</h5>
2322<pre>
2323 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2324 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2325 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2326 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2327 &lt;result&gt; = lshr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2328</pre>
2329</div>
2330
2331<!-- _______________________________________________________________________ -->
2332<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2333Instruction</a> </div>
2334<div class="doc_text">
2335
2336<h5>Syntax:</h5>
2337<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2338</pre>
2339
2340<h5>Overview:</h5>
2341<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2342operand shifted to the right a specified number of bits with sign extension.</p>
2343
2344<h5>Arguments:</h5>
2345<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2346<a href="#t_integer">integer</a> type.</p>
2347
2348<h5>Semantics:</h5>
2349<p>This instruction always performs an arithmetic shift right operation,
2350The most significant bits of the result will be filled with the sign bit
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2351of <tt>var1</tt>. If <tt>var2</tt> is (statically or dynamically) equal to or
2352larger than the number of bits in <tt>var1</tt>, the result is undefined.
2353</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2354
2355<h5>Example:</h5>
2356<pre>
2357 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2358 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2359 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2360 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2361 &lt;result&gt; = ashr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2362</pre>
2363</div>
2364
2365<!-- _______________________________________________________________________ -->
2366<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2367Instruction</a> </div>
2368<div class="doc_text">
2369<h5>Syntax:</h5>
2370<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2371</pre>
2372<h5>Overview:</h5>
2373<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2374its two operands.</p>
2375<h5>Arguments:</h5>
2376<p>The two arguments to the '<tt>and</tt>' instruction must be <a
2377 href="#t_integer">integer</a> values. Both arguments must have
2378identical types.</p>
2379<h5>Semantics:</h5>
2380<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
2381<p> </p>
2382<div style="align: center">
2383<table border="1" cellspacing="0" cellpadding="4">
2384 <tbody>
2385 <tr>
2386 <td>In0</td>
2387 <td>In1</td>
2388 <td>Out</td>
2389 </tr>
2390 <tr>
2391 <td>0</td>
2392 <td>0</td>
2393 <td>0</td>
2394 </tr>
2395 <tr>
2396 <td>0</td>
2397 <td>1</td>
2398 <td>0</td>
2399 </tr>
2400 <tr>
2401 <td>1</td>
2402 <td>0</td>
2403 <td>0</td>
2404 </tr>
2405 <tr>
2406 <td>1</td>
2407 <td>1</td>
2408 <td>1</td>
2409 </tr>
2410 </tbody>
2411</table>
2412</div>
2413<h5>Example:</h5>
2414<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2415 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2416 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
2417</pre>
2418</div>
2419<!-- _______________________________________________________________________ -->
2420<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
2421<div class="doc_text">
2422<h5>Syntax:</h5>
2423<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2424</pre>
2425<h5>Overview:</h5>
2426<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2427or of its two operands.</p>
2428<h5>Arguments:</h5>
2429<p>The two arguments to the '<tt>or</tt>' instruction must be <a
2430 href="#t_integer">integer</a> values. Both arguments must have
2431identical types.</p>
2432<h5>Semantics:</h5>
2433<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
2434<p> </p>
2435<div style="align: center">
2436<table border="1" cellspacing="0" cellpadding="4">
2437 <tbody>
2438 <tr>
2439 <td>In0</td>
2440 <td>In1</td>
2441 <td>Out</td>
2442 </tr>
2443 <tr>
2444 <td>0</td>
2445 <td>0</td>
2446 <td>0</td>
2447 </tr>
2448 <tr>
2449 <td>0</td>
2450 <td>1</td>
2451 <td>1</td>
2452 </tr>
2453 <tr>
2454 <td>1</td>
2455 <td>0</td>
2456 <td>1</td>
2457 </tr>
2458 <tr>
2459 <td>1</td>
2460 <td>1</td>
2461 <td>1</td>
2462 </tr>
2463 </tbody>
2464</table>
2465</div>
2466<h5>Example:</h5>
2467<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2468 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2469 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
2470</pre>
2471</div>
2472<!-- _______________________________________________________________________ -->
2473<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2474Instruction</a> </div>
2475<div class="doc_text">
2476<h5>Syntax:</h5>
2477<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2478</pre>
2479<h5>Overview:</h5>
2480<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2481or of its two operands. The <tt>xor</tt> is used to implement the
2482"one's complement" operation, which is the "~" operator in C.</p>
2483<h5>Arguments:</h5>
2484<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
2485 href="#t_integer">integer</a> values. Both arguments must have
2486identical types.</p>
2487<h5>Semantics:</h5>
2488<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
2489<p> </p>
2490<div style="align: center">
2491<table border="1" cellspacing="0" cellpadding="4">
2492 <tbody>
2493 <tr>
2494 <td>In0</td>
2495 <td>In1</td>
2496 <td>Out</td>
2497 </tr>
2498 <tr>
2499 <td>0</td>
2500 <td>0</td>
2501 <td>0</td>
2502 </tr>
2503 <tr>
2504 <td>0</td>
2505 <td>1</td>
2506 <td>1</td>
2507 </tr>
2508 <tr>
2509 <td>1</td>
2510 <td>0</td>
2511 <td>1</td>
2512 </tr>
2513 <tr>
2514 <td>1</td>
2515 <td>1</td>
2516 <td>0</td>
2517 </tr>
2518 </tbody>
2519</table>
2520</div>
2521<p> </p>
2522<h5>Example:</h5>
2523<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2524 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2525 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2526 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
2527</pre>
2528</div>
2529
2530<!-- ======================================================================= -->
2531<div class="doc_subsection">
2532 <a name="vectorops">Vector Operations</a>
2533</div>
2534
2535<div class="doc_text">
2536
2537<p>LLVM supports several instructions to represent vector operations in a
2538target-independent manner. These instructions cover the element-access and
2539vector-specific operations needed to process vectors effectively. While LLVM
2540does directly support these vector operations, many sophisticated algorithms
2541will want to use target-specific intrinsics to take full advantage of a specific
2542target.</p>
2543
2544</div>
2545
2546<!-- _______________________________________________________________________ -->
2547<div class="doc_subsubsection">
2548 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2549</div>
2550
2551<div class="doc_text">
2552
2553<h5>Syntax:</h5>
2554
2555<pre>
2556 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2557</pre>
2558
2559<h5>Overview:</h5>
2560
2561<p>
2562The '<tt>extractelement</tt>' instruction extracts a single scalar
2563element from a vector at a specified index.
2564</p>
2565
2566
2567<h5>Arguments:</h5>
2568
2569<p>
2570The first operand of an '<tt>extractelement</tt>' instruction is a
2571value of <a href="#t_vector">vector</a> type. The second operand is
2572an index indicating the position from which to extract the element.
2573The index may be a variable.</p>
2574
2575<h5>Semantics:</h5>
2576
2577<p>
2578The result is a scalar of the same type as the element type of
2579<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2580<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2581results are undefined.
2582</p>
2583
2584<h5>Example:</h5>
2585
2586<pre>
2587 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
2588</pre>
2589</div>
2590
2591
2592<!-- _______________________________________________________________________ -->
2593<div class="doc_subsubsection">
2594 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2595</div>
2596
2597<div class="doc_text">
2598
2599<h5>Syntax:</h5>
2600
2601<pre>
2602 &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>
2603</pre>
2604
2605<h5>Overview:</h5>
2606
2607<p>
2608The '<tt>insertelement</tt>' instruction inserts a scalar
2609element into a vector at a specified index.
2610</p>
2611
2612
2613<h5>Arguments:</h5>
2614
2615<p>
2616The first operand of an '<tt>insertelement</tt>' instruction is a
2617value of <a href="#t_vector">vector</a> type. The second operand is a
2618scalar value whose type must equal the element type of the first
2619operand. The third operand is an index indicating the position at
2620which to insert the value. The index may be a variable.</p>
2621
2622<h5>Semantics:</h5>
2623
2624<p>
2625The result is a vector of the same type as <tt>val</tt>. Its
2626element values are those of <tt>val</tt> except at position
2627<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2628exceeds the length of <tt>val</tt>, the results are undefined.
2629</p>
2630
2631<h5>Example:</h5>
2632
2633<pre>
2634 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
2635</pre>
2636</div>
2637
2638<!-- _______________________________________________________________________ -->
2639<div class="doc_subsubsection">
2640 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2641</div>
2642
2643<div class="doc_text">
2644
2645<h5>Syntax:</h5>
2646
2647<pre>
2648 &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>
2649</pre>
2650
2651<h5>Overview:</h5>
2652
2653<p>
2654The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2655from two input vectors, returning a vector of the same type.
2656</p>
2657
2658<h5>Arguments:</h5>
2659
2660<p>
2661The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2662with types that match each other and types that match the result of the
2663instruction. The third argument is a shuffle mask, which has the same number
2664of elements as the other vector type, but whose element type is always 'i32'.
2665</p>
2666
2667<p>
2668The shuffle mask operand is required to be a constant vector with either
2669constant integer or undef values.
2670</p>
2671
2672<h5>Semantics:</h5>
2673
2674<p>
2675The elements of the two input vectors are numbered from left to right across
2676both of the vectors. The shuffle mask operand specifies, for each element of
2677the result vector, which element of the two input registers the result element
2678gets. The element selector may be undef (meaning "don't care") and the second
2679operand may be undef if performing a shuffle from only one vector.
2680</p>
2681
2682<h5>Example:</h5>
2683
2684<pre>
2685 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2686 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2687 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2688 &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.
2689</pre>
2690</div>
2691
2692
2693<!-- ======================================================================= -->
2694<div class="doc_subsection">
2695 <a name="memoryops">Memory Access and Addressing Operations</a>
2696</div>
2697
2698<div class="doc_text">
2699
2700<p>A key design point of an SSA-based representation is how it
2701represents memory. In LLVM, no memory locations are in SSA form, which
2702makes things very simple. This section describes how to read, write,
2703allocate, and free memory in LLVM.</p>
2704
2705</div>
2706
2707<!-- _______________________________________________________________________ -->
2708<div class="doc_subsubsection">
2709 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2710</div>
2711
2712<div class="doc_text">
2713
2714<h5>Syntax:</h5>
2715
2716<pre>
2717 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2718</pre>
2719
2720<h5>Overview:</h5>
2721
2722<p>The '<tt>malloc</tt>' instruction allocates memory from the system
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]2723heap and returns a pointer to it. The object is always allocated in the generic
2724address space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2725
2726<h5>Arguments:</h5>
2727
2728<p>The '<tt>malloc</tt>' instruction allocates
2729<tt>sizeof(&lt;type&gt;)*NumElements</tt>
2730bytes of memory from the operating system and returns a pointer of the
2731appropriate type to the program. If "NumElements" is specified, it is the
2732number of elements allocated. If an alignment is specified, the value result
2733of the allocation is guaranteed to be aligned to at least that boundary. If
2734not specified, or if zero, the target can choose to align the allocation on any
2735convenient boundary.</p>
2736
2737<p>'<tt>type</tt>' must be a sized type.</p>
2738
2739<h5>Semantics:</h5>
2740
2741<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2742a pointer is returned.</p>
2743
2744<h5>Example:</h5>
2745
2746<pre>
2747 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
2748
2749 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2750 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2751 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2752 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2753 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
2754</pre>
2755</div>
2756
2757<!-- _______________________________________________________________________ -->
2758<div class="doc_subsubsection">
2759 <a name="i_free">'<tt>free</tt>' Instruction</a>
2760</div>
2761
2762<div class="doc_text">
2763
2764<h5>Syntax:</h5>
2765
2766<pre>
2767 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
2768</pre>
2769
2770<h5>Overview:</h5>
2771
2772<p>The '<tt>free</tt>' instruction returns memory back to the unused
2773memory heap to be reallocated in the future.</p>
2774
2775<h5>Arguments:</h5>
2776
2777<p>'<tt>value</tt>' shall be a pointer value that points to a value
2778that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2779instruction.</p>
2780
2781<h5>Semantics:</h5>
2782
2783<p>Access to the memory pointed to by the pointer is no longer defined
2784after this instruction executes.</p>
2785
2786<h5>Example:</h5>
2787
2788<pre>
2789 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2790 free [4 x i8]* %array
2791</pre>
2792</div>
2793
2794<!-- _______________________________________________________________________ -->
2795<div class="doc_subsubsection">
2796 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2797</div>
2798
2799<div class="doc_text">
2800
2801<h5>Syntax:</h5>
2802
2803<pre>
2804 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2805</pre>
2806
2807<h5>Overview:</h5>
2808
2809<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
2810currently executing function, to be automatically released when this function
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]2811returns to its caller. The object is always allocated in the generic address
2812space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2813
2814<h5>Arguments:</h5>
2815
2816<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
2817bytes of memory on the runtime stack, returning a pointer of the
2818appropriate type to the program. If "NumElements" is specified, it is the
2819number of elements allocated. If an alignment is specified, the value result
2820of the allocation is guaranteed to be aligned to at least that boundary. If
2821not specified, or if zero, the target can choose to align the allocation on any
2822convenient boundary.</p>
2823
2824<p>'<tt>type</tt>' may be any sized type.</p>
2825
2826<h5>Semantics:</h5>
2827
2828<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
2829memory is automatically released when the function returns. The '<tt>alloca</tt>'
2830instruction is commonly used to represent automatic variables that must
2831have an address available. When the function returns (either with the <tt><a
2832 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
2833instructions), the memory is reclaimed.</p>
2834
2835<h5>Example:</h5>
2836
2837<pre>
2838 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2839 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2840 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2841 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
2842</pre>
2843</div>
2844
2845<!-- _______________________________________________________________________ -->
2846<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2847Instruction</a> </div>
2848<div class="doc_text">
2849<h5>Syntax:</h5>
2850<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>
2851<h5>Overview:</h5>
2852<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
2853<h5>Arguments:</h5>
2854<p>The argument to the '<tt>load</tt>' instruction specifies the memory
2855address from which to load. The pointer must point to a <a
2856 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
2857marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
2858the number or order of execution of this <tt>load</tt> with other
2859volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2860instructions. </p>
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2861<p>
2862The optional "align" argument specifies the alignment of the operation
2863(that is, the alignment of the memory address). A value of 0 or an
2864omitted "align" argument means that the operation has the preferential
2865alignment for the target. It is the responsibility of the code emitter
2866to ensure that the alignment information is correct. Overestimating
2867the alignment results in an undefined behavior. Underestimating the
2868alignment may produce less efficient code. An alignment of 1 is always
2869safe.
2870</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2871<h5>Semantics:</h5>
2872<p>The location of memory pointed to is loaded.</p>
2873<h5>Examples:</h5>
2874<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
2875 <a
2876 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2877 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
2878</pre>
2879</div>
2880<!-- _______________________________________________________________________ -->
2881<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2882Instruction</a> </div>
2883<div class="doc_text">
2884<h5>Syntax:</h5>
2885<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2886 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2887</pre>
2888<h5>Overview:</h5>
2889<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
2890<h5>Arguments:</h5>
2891<p>There are two arguments to the '<tt>store</tt>' instruction: a value
2892to store and an address at which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
2893operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
2894operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
2895optimizer is not allowed to modify the number or order of execution of
2896this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2897 href="#i_store">store</a></tt> instructions.</p>
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2898<p>
2899The optional "align" argument specifies the alignment of the operation
2900(that is, the alignment of the memory address). A value of 0 or an
2901omitted "align" argument means that the operation has the preferential
2902alignment for the target. It is the responsibility of the code emitter
2903to ensure that the alignment information is correct. Overestimating
2904the alignment results in an undefined behavior. Underestimating the
2905alignment may produce less efficient code. An alignment of 1 is always
2906safe.
2907</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2908<h5>Semantics:</h5>
2909<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2910at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
2911<h5>Example:</h5>
2912<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Bill Wendling63ffa142007-10-22 05:10:05 +0000[diff] [blame]2913 store i32 3, i32* %ptr <i>; yields {void}</i>
2914 %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]2915</pre>
2916</div>
2917
2918<!-- _______________________________________________________________________ -->
2919<div class="doc_subsubsection">
2920 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2921</div>
2922
2923<div class="doc_text">
2924<h5>Syntax:</h5>
2925<pre>
2926 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2927</pre>
2928
2929<h5>Overview:</h5>
2930
2931<p>
2932The '<tt>getelementptr</tt>' instruction is used to get the address of a
2933subelement of an aggregate data structure.</p>
2934
2935<h5>Arguments:</h5>
2936
2937<p>This instruction takes a list of integer operands that indicate what
2938elements of the aggregate object to index to. The actual types of the arguments
2939provided depend on the type of the first pointer argument. The
2940'<tt>getelementptr</tt>' instruction is used to index down through the type
2941levels of a structure or to a specific index in an array. When indexing into a
2942structure, only <tt>i32</tt> integer constants are allowed. When indexing
2943into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2944be sign extended to 64-bit values.</p>
2945
2946<p>For example, let's consider a C code fragment and how it gets
2947compiled to LLVM:</p>
2948
2949<div class="doc_code">
2950<pre>
2951struct RT {
2952 char A;
2953 int B[10][20];
2954 char C;
2955};
2956struct ST {
2957 int X;
2958 double Y;
2959 struct RT Z;
2960};
2961
2962int *foo(struct ST *s) {
2963 return &amp;s[1].Z.B[5][13];
2964}
2965</pre>
2966</div>
2967
2968<p>The LLVM code generated by the GCC frontend is:</p>
2969
2970<div class="doc_code">
2971<pre>
2972%RT = type { i8 , [10 x [20 x i32]], i8 }
2973%ST = type { i32, double, %RT }
2974
2975define i32* %foo(%ST* %s) {
2976entry:
2977 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2978 ret i32* %reg
2979}
2980</pre>
2981</div>
2982
2983<h5>Semantics:</h5>
2984
2985<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
2986on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
2987and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
2988<a href="#t_integer">integer</a> type but the value will always be sign extended
2989to 64-bits. <a href="#t_struct">Structure</a> types require <tt>i32</tt>
2990<b>constants</b>.</p>
2991
2992<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
2993type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
2994}</tt>' type, a structure. The second index indexes into the third element of
2995the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2996i8 }</tt>' type, another structure. The third index indexes into the second
2997element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
2998array. The two dimensions of the array are subscripted into, yielding an
2999'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
3000to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
3001
3002<p>Note that it is perfectly legal to index partially through a
3003structure, returning a pointer to an inner element. Because of this,
3004the LLVM code for the given testcase is equivalent to:</p>
3005
3006<pre>
3007 define i32* %foo(%ST* %s) {
3008 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
3009 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
3010 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
3011 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
3012 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
3013 ret i32* %t5
3014 }
3015</pre>
3016
3017<p>Note that it is undefined to access an array out of bounds: array and
3018pointer indexes must always be within the defined bounds of the array type.
3019The one exception for this rules is zero length arrays. These arrays are
3020defined to be accessible as variable length arrays, which requires access
3021beyond the zero'th element.</p>
3022
3023<p>The getelementptr instruction is often confusing. For some more insight
3024into how it works, see <a href="GetElementPtr.html">the getelementptr
3025FAQ</a>.</p>
3026
3027<h5>Example:</h5>
3028
3029<pre>
3030 <i>; yields [12 x i8]*:aptr</i>
3031 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
3032</pre>
3033</div>
3034
3035<!-- ======================================================================= -->
3036<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
3037</div>
3038<div class="doc_text">
3039<p>The instructions in this category are the conversion instructions (casting)
3040which all take a single operand and a type. They perform various bit conversions
3041on the operand.</p>
3042</div>
3043
3044<!-- _______________________________________________________________________ -->
3045<div class="doc_subsubsection">
3046 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
3047</div>
3048<div class="doc_text">
3049
3050<h5>Syntax:</h5>
3051<pre>
3052 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3053</pre>
3054
3055<h5>Overview:</h5>
3056<p>
3057The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
3058</p>
3059
3060<h5>Arguments:</h5>
3061<p>
3062The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
3063be an <a href="#t_integer">integer</a> type, and a type that specifies the size
3064and type of the result, which must be an <a href="#t_integer">integer</a>
3065type. The bit size of <tt>value</tt> must be larger than the bit size of
3066<tt>ty2</tt>. Equal sized types are not allowed.</p>
3067
3068<h5>Semantics:</h5>
3069<p>
3070The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
3071and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
3072larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
3073It will always truncate bits.</p>
3074
3075<h5>Example:</h5>
3076<pre>
3077 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
3078 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
3079 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
3080</pre>
3081</div>
3082
3083<!-- _______________________________________________________________________ -->
3084<div class="doc_subsubsection">
3085 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3086</div>
3087<div class="doc_text">
3088
3089<h5>Syntax:</h5>
3090<pre>
3091 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3092</pre>
3093
3094<h5>Overview:</h5>
3095<p>The '<tt>zext</tt>' instruction zero extends its operand to type
3096<tt>ty2</tt>.</p>
3097
3098
3099<h5>Arguments:</h5>
3100<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3101<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3102also be of <a href="#t_integer">integer</a> type. The bit size of the
3103<tt>value</tt> must be smaller than the bit size of the destination type,
3104<tt>ty2</tt>.</p>
3105
3106<h5>Semantics:</h5>
3107<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3108bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3109
3110<p>When zero extending from i1, the result will always be either 0 or 1.</p>
3111
3112<h5>Example:</h5>
3113<pre>
3114 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3115 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3116</pre>
3117</div>
3118
3119<!-- _______________________________________________________________________ -->
3120<div class="doc_subsubsection">
3121 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3122</div>
3123<div class="doc_text">
3124
3125<h5>Syntax:</h5>
3126<pre>
3127 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3128</pre>
3129
3130<h5>Overview:</h5>
3131<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3132
3133<h5>Arguments:</h5>
3134<p>
3135The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3136<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3137also be of <a href="#t_integer">integer</a> type. The bit size of the
3138<tt>value</tt> must be smaller than the bit size of the destination type,
3139<tt>ty2</tt>.</p>
3140
3141<h5>Semantics:</h5>
3142<p>
3143The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3144bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3145the type <tt>ty2</tt>.</p>
3146
3147<p>When sign extending from i1, the extension always results in -1 or 0.</p>
3148
3149<h5>Example:</h5>
3150<pre>
3151 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3152 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3153</pre>
3154</div>
3155
3156<!-- _______________________________________________________________________ -->
3157<div class="doc_subsubsection">
3158 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3159</div>
3160
3161<div class="doc_text">
3162
3163<h5>Syntax:</h5>
3164
3165<pre>
3166 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3167</pre>
3168
3169<h5>Overview:</h5>
3170<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
3171<tt>ty2</tt>.</p>
3172
3173
3174<h5>Arguments:</h5>
3175<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
3176 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
3177cast it to. The size of <tt>value</tt> must be larger than the size of
3178<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
3179<i>no-op cast</i>.</p>
3180
3181<h5>Semantics:</h5>
3182<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
3183<a href="#t_floating">floating point</a> type to a smaller
3184<a href="#t_floating">floating point</a> type. If the value cannot fit within
3185the destination type, <tt>ty2</tt>, then the results are undefined.</p>
3186
3187<h5>Example:</h5>
3188<pre>
3189 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
3190 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
3191</pre>
3192</div>
3193
3194<!-- _______________________________________________________________________ -->
3195<div class="doc_subsubsection">
3196 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
3197</div>
3198<div class="doc_text">
3199
3200<h5>Syntax:</h5>
3201<pre>
3202 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3203</pre>
3204
3205<h5>Overview:</h5>
3206<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
3207floating point value.</p>
3208
3209<h5>Arguments:</h5>
3210<p>The '<tt>fpext</tt>' instruction takes a
3211<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
3212and a <a href="#t_floating">floating point</a> type to cast it to. The source
3213type must be smaller than the destination type.</p>
3214
3215<h5>Semantics:</h5>
3216<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
3217<a href="#t_floating">floating point</a> type to a larger
3218<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
3219used to make a <i>no-op cast</i> because it always changes bits. Use
3220<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
3221
3222<h5>Example:</h5>
3223<pre>
3224 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
3225 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
3226</pre>
3227</div>
3228
3229<!-- _______________________________________________________________________ -->
3230<div class="doc_subsubsection">
3231 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
3232</div>
3233<div class="doc_text">
3234
3235<h5>Syntax:</h5>
3236<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3237 &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]3238</pre>
3239
3240<h5>Overview:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3241<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3242unsigned integer equivalent of type <tt>ty2</tt>.
3243</p>
3244
3245<h5>Arguments:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3246<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]3247scalar or vector <a href="#t_floating">floating point</a> value, and a type
3248to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3249type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3250vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3251
3252<h5>Semantics:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3253<p> The '<tt>fptoui</tt>' instruction converts its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3254<a href="#t_floating">floating point</a> operand into the nearest (rounding
3255towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3256the results are undefined.</p>
3257
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3258<h5>Example:</h5>
3259<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3260 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3261 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3262 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3263</pre>
3264</div>
3265
3266<!-- _______________________________________________________________________ -->
3267<div class="doc_subsubsection">
3268 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
3269</div>
3270<div class="doc_text">
3271
3272<h5>Syntax:</h5>
3273<pre>
3274 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3275</pre>
3276
3277<h5>Overview:</h5>
3278<p>The '<tt>fptosi</tt>' instruction converts
3279<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
3280</p>
3281
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3282<h5>Arguments:</h5>
3283<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]3284scalar or vector <a href="#t_floating">floating point</a> value, and a type
3285to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3286type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3287vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3288
3289<h5>Semantics:</h5>
3290<p>The '<tt>fptosi</tt>' instruction converts its
3291<a href="#t_floating">floating point</a> operand into the nearest (rounding
3292towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3293the results are undefined.</p>
3294
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3295<h5>Example:</h5>
3296<pre>
3297 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3298 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3299 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
3300</pre>
3301</div>
3302
3303<!-- _______________________________________________________________________ -->
3304<div class="doc_subsubsection">
3305 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
3306</div>
3307<div class="doc_text">
3308
3309<h5>Syntax:</h5>
3310<pre>
3311 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3312</pre>
3313
3314<h5>Overview:</h5>
3315<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
3316integer and converts that value to the <tt>ty2</tt> type.</p>
3317
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3318<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3319<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
3320scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3321to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3322type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3323floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3324
3325<h5>Semantics:</h5>
3326<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
3327integer quantity and converts it to the corresponding floating point value. If
3328the value cannot fit in the floating point value, the results are undefined.</p>
3329
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3330<h5>Example:</h5>
3331<pre>
3332 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3333 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
3334</pre>
3335</div>
3336
3337<!-- _______________________________________________________________________ -->
3338<div class="doc_subsubsection">
3339 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
3340</div>
3341<div class="doc_text">
3342
3343<h5>Syntax:</h5>
3344<pre>
3345 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3346</pre>
3347
3348<h5>Overview:</h5>
3349<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
3350integer and converts that value to the <tt>ty2</tt> type.</p>
3351
3352<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3353<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
3354scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3355to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3356type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3357floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3358
3359<h5>Semantics:</h5>
3360<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
3361integer quantity and converts it to the corresponding floating point value. If
3362the value cannot fit in the floating point value, the results are undefined.</p>
3363
3364<h5>Example:</h5>
3365<pre>
3366 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3367 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
3368</pre>
3369</div>
3370
3371<!-- _______________________________________________________________________ -->
3372<div class="doc_subsubsection">
3373 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3374</div>
3375<div class="doc_text">
3376
3377<h5>Syntax:</h5>
3378<pre>
3379 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3380</pre>
3381
3382<h5>Overview:</h5>
3383<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3384the integer type <tt>ty2</tt>.</p>
3385
3386<h5>Arguments:</h5>
3387<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3388must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
3389<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3390
3391<h5>Semantics:</h5>
3392<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3393<tt>ty2</tt> by interpreting the pointer value as an integer and either
3394truncating or zero extending that value to the size of the integer type. If
3395<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3396<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3397are the same size, then nothing is done (<i>no-op cast</i>) other than a type
3398change.</p>
3399
3400<h5>Example:</h5>
3401<pre>
3402 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
3403 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
3404</pre>
3405</div>
3406
3407<!-- _______________________________________________________________________ -->
3408<div class="doc_subsubsection">
3409 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3410</div>
3411<div class="doc_text">
3412
3413<h5>Syntax:</h5>
3414<pre>
3415 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3416</pre>
3417
3418<h5>Overview:</h5>
3419<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3420a pointer type, <tt>ty2</tt>.</p>
3421
3422<h5>Arguments:</h5>
3423<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
3424value to cast, and a type to cast it to, which must be a
3425<a href="#t_pointer">pointer</a> type.
3426
3427<h5>Semantics:</h5>
3428<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3429<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3430the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3431size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3432the size of a pointer then a zero extension is done. If they are the same size,
3433nothing is done (<i>no-op cast</i>).</p>
3434
3435<h5>Example:</h5>
3436<pre>
3437 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
3438 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
3439 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
3440</pre>
3441</div>
3442
3443<!-- _______________________________________________________________________ -->
3444<div class="doc_subsubsection">
3445 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
3446</div>
3447<div class="doc_text">
3448
3449<h5>Syntax:</h5>
3450<pre>
3451 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3452</pre>
3453
3454<h5>Overview:</h5>
3455<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3456<tt>ty2</tt> without changing any bits.</p>
3457
3458<h5>Arguments:</h5>
3459<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
3460a first class value, and a type to cast it to, which must also be a <a
3461 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
3462and the destination type, <tt>ty2</tt>, must be identical. If the source
3463type is a pointer, the destination type must also be a pointer.</p>
3464
3465<h5>Semantics:</h5>
3466<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3467<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3468this conversion. The conversion is done as if the <tt>value</tt> had been
3469stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3470converted to other pointer types with this instruction. To convert pointers to
3471other types, use the <a href="#i_inttoptr">inttoptr</a> or
3472<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
3473
3474<h5>Example:</h5>
3475<pre>
3476 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3477 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3478 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
3479</pre>
3480</div>
3481
3482<!-- ======================================================================= -->
3483<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3484<div class="doc_text">
3485<p>The instructions in this category are the "miscellaneous"
3486instructions, which defy better classification.</p>
3487</div>
3488
3489<!-- _______________________________________________________________________ -->
3490<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3491</div>
3492<div class="doc_text">
3493<h5>Syntax:</h5>
3494<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3495</pre>
3496<h5>Overview:</h5>
3497<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3498of its two integer operands.</p>
3499<h5>Arguments:</h5>
3500<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3501the condition code indicating the kind of comparison to perform. It is not
3502a value, just a keyword. The possible condition code are:
3503<ol>
3504 <li><tt>eq</tt>: equal</li>
3505 <li><tt>ne</tt>: not equal </li>
3506 <li><tt>ugt</tt>: unsigned greater than</li>
3507 <li><tt>uge</tt>: unsigned greater or equal</li>
3508 <li><tt>ult</tt>: unsigned less than</li>
3509 <li><tt>ule</tt>: unsigned less or equal</li>
3510 <li><tt>sgt</tt>: signed greater than</li>
3511 <li><tt>sge</tt>: signed greater or equal</li>
3512 <li><tt>slt</tt>: signed less than</li>
3513 <li><tt>sle</tt>: signed less or equal</li>
3514</ol>
3515<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
3516<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
3517<h5>Semantics:</h5>
3518<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3519the condition code given as <tt>cond</tt>. The comparison performed always
3520yields a <a href="#t_primitive">i1</a> result, as follows:
3521<ol>
3522 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3523 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3524 </li>
3525 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3526 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3527 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3528 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3529 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3530 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3531 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3532 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3533 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3534 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3535 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3536 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3537 <li><tt>sge</tt>: interprets the operands as signed values and yields
3538 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3539 <li><tt>slt</tt>: interprets the operands as signed values and yields
3540 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3541 <li><tt>sle</tt>: interprets the operands as signed values and yields
3542 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3543</ol>
3544<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3545values are compared as if they were integers.</p>
3546
3547<h5>Example:</h5>
3548<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3549 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3550 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3551 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3552 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3553 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
3554</pre>
3555</div>
3556
3557<!-- _______________________________________________________________________ -->
3558<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3559</div>
3560<div class="doc_text">
3561<h5>Syntax:</h5>
3562<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3563</pre>
3564<h5>Overview:</h5>
3565<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3566of its floating point operands.</p>
3567<h5>Arguments:</h5>
3568<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3569the condition code indicating the kind of comparison to perform. It is not
3570a value, just a keyword. The possible condition code are:
3571<ol>
3572 <li><tt>false</tt>: no comparison, always returns false</li>
3573 <li><tt>oeq</tt>: ordered and equal</li>
3574 <li><tt>ogt</tt>: ordered and greater than </li>
3575 <li><tt>oge</tt>: ordered and greater than or equal</li>
3576 <li><tt>olt</tt>: ordered and less than </li>
3577 <li><tt>ole</tt>: ordered and less than or equal</li>
3578 <li><tt>one</tt>: ordered and not equal</li>
3579 <li><tt>ord</tt>: ordered (no nans)</li>
3580 <li><tt>ueq</tt>: unordered or equal</li>
3581 <li><tt>ugt</tt>: unordered or greater than </li>
3582 <li><tt>uge</tt>: unordered or greater than or equal</li>
3583 <li><tt>ult</tt>: unordered or less than </li>
3584 <li><tt>ule</tt>: unordered or less than or equal</li>
3585 <li><tt>une</tt>: unordered or not equal</li>
3586 <li><tt>uno</tt>: unordered (either nans)</li>
3587 <li><tt>true</tt>: no comparison, always returns true</li>
3588</ol>
3589<p><i>Ordered</i> means that neither operand is a QNAN while
3590<i>unordered</i> means that either operand may be a QNAN.</p>
3591<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3592<a href="#t_floating">floating point</a> typed. They must have identical
3593types.</p>
3594<h5>Semantics:</h5>
3595<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3596the condition code given as <tt>cond</tt>. The comparison performed always
3597yields a <a href="#t_primitive">i1</a> result, as follows:
3598<ol>
3599 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
3600 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3601 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3602 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3603 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
3604 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3605 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3606 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3607 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3608 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3609 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3610 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3611 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3612 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3613 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
3614 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3615 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
3616 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3617 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
3618 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3619 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
3620 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3621 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
3622 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3623 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
3624 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3625 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
3626 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3627</ol>
3628
3629<h5>Example:</h5>
3630<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3631 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3632 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3633 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3634</pre>
3635</div>
3636
3637<!-- _______________________________________________________________________ -->
3638<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3639Instruction</a> </div>
3640<div class="doc_text">
3641<h5>Syntax:</h5>
3642<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3643<h5>Overview:</h5>
3644<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3645the SSA graph representing the function.</p>
3646<h5>Arguments:</h5>
3647<p>The type of the incoming values is specified with the first type
3648field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3649as arguments, with one pair for each predecessor basic block of the
3650current block. Only values of <a href="#t_firstclass">first class</a>
3651type may be used as the value arguments to the PHI node. Only labels
3652may be used as the label arguments.</p>
3653<p>There must be no non-phi instructions between the start of a basic
3654block and the PHI instructions: i.e. PHI instructions must be first in
3655a basic block.</p>
3656<h5>Semantics:</h5>
3657<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
3658specified by the pair corresponding to the predecessor basic block that executed
3659just prior to the current block.</p>
3660<h5>Example:</h5>
3661<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>
3662</div>
3663
3664<!-- _______________________________________________________________________ -->
3665<div class="doc_subsubsection">
3666 <a name="i_select">'<tt>select</tt>' Instruction</a>
3667</div>
3668
3669<div class="doc_text">
3670
3671<h5>Syntax:</h5>
3672
3673<pre>
3674 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
3675</pre>
3676
3677<h5>Overview:</h5>
3678
3679<p>
3680The '<tt>select</tt>' instruction is used to choose one value based on a
3681condition, without branching.
3682</p>
3683
3684
3685<h5>Arguments:</h5>
3686
3687<p>
3688The '<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.
3689</p>
3690
3691<h5>Semantics:</h5>
3692
3693<p>
3694If the boolean condition evaluates to true, the instruction returns the first
3695value argument; otherwise, it returns the second value argument.
3696</p>
3697
3698<h5>Example:</h5>
3699
3700<pre>
3701 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
3702</pre>
3703</div>
3704
3705
3706<!-- _______________________________________________________________________ -->
3707<div class="doc_subsubsection">
3708 <a name="i_call">'<tt>call</tt>' Instruction</a>
3709</div>
3710
3711<div class="doc_text">
3712
3713<h5>Syntax:</h5>
3714<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3715 &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]3716</pre>
3717
3718<h5>Overview:</h5>
3719
3720<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
3721
3722<h5>Arguments:</h5>
3723
3724<p>This instruction requires several arguments:</p>
3725
3726<ol>
3727 <li>
3728 <p>The optional "tail" marker indicates whether the callee function accesses
3729 any allocas or varargs in the caller. If the "tail" marker is present, the
3730 function call is eligible for tail call optimization. Note that calls may
3731 be marked "tail" even if they do not occur before a <a
3732 href="#i_ret"><tt>ret</tt></a> instruction.
3733 </li>
3734 <li>
3735 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
3736 convention</a> the call should use. If none is specified, the call defaults
3737 to using C calling conventions.
3738 </li>
3739 <li>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3740 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
3741 the type of the return value. Functions that return no value are marked
3742 <tt><a href="#t_void">void</a></tt>.</p>
3743 </li>
3744 <li>
3745 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
3746 value being invoked. The argument types must match the types implied by
3747 this signature. This type can be omitted if the function is not varargs
3748 and if the function type does not return a pointer to a function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3749 </li>
3750 <li>
3751 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3752 be invoked. In most cases, this is a direct function invocation, but
3753 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
3754 to function value.</p>
3755 </li>
3756 <li>
3757 <p>'<tt>function args</tt>': argument list whose types match the
3758 function signature argument types. All arguments must be of
3759 <a href="#t_firstclass">first class</a> type. If the function signature
3760 indicates the function accepts a variable number of arguments, the extra
3761 arguments can be specified.</p>
3762 </li>
3763</ol>
3764
3765<h5>Semantics:</h5>
3766
3767<p>The '<tt>call</tt>' instruction is used to cause control flow to
3768transfer to a specified function, with its incoming arguments bound to
3769the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3770instruction in the called function, control flow continues with the
3771instruction after the function call, and the return value of the
3772function is bound to the result argument. This is a simpler case of
3773the <a href="#i_invoke">invoke</a> instruction.</p>
3774
3775<h5>Example:</h5>
3776
3777<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3778 %retval = call i32 @test(i32 %argc)
3779 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42);
3780 %X = tail call i32 @foo()
3781 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo()
3782 %Z = call void %foo(i8 97 signext)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3783</pre>
3784
3785</div>
3786
3787<!-- _______________________________________________________________________ -->
3788<div class="doc_subsubsection">
3789 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
3790</div>
3791
3792<div class="doc_text">
3793
3794<h5>Syntax:</h5>
3795
3796<pre>
3797 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
3798</pre>
3799
3800<h5>Overview:</h5>
3801
3802<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
3803the "variable argument" area of a function call. It is used to implement the
3804<tt>va_arg</tt> macro in C.</p>
3805
3806<h5>Arguments:</h5>
3807
3808<p>This instruction takes a <tt>va_list*</tt> value and the type of
3809the argument. It returns a value of the specified argument type and
3810increments the <tt>va_list</tt> to point to the next argument. The
3811actual type of <tt>va_list</tt> is target specific.</p>
3812
3813<h5>Semantics:</h5>
3814
3815<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3816type from the specified <tt>va_list</tt> and causes the
3817<tt>va_list</tt> to point to the next argument. For more information,
3818see the variable argument handling <a href="#int_varargs">Intrinsic
3819Functions</a>.</p>
3820
3821<p>It is legal for this instruction to be called in a function which does not
3822take a variable number of arguments, for example, the <tt>vfprintf</tt>
3823function.</p>
3824
3825<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
3826href="#intrinsics">intrinsic function</a> because it takes a type as an
3827argument.</p>
3828
3829<h5>Example:</h5>
3830
3831<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3832
3833</div>
3834
3835<!-- *********************************************************************** -->
3836<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3837<!-- *********************************************************************** -->
3838
3839<div class="doc_text">
3840
3841<p>LLVM supports the notion of an "intrinsic function". These functions have
3842well known names and semantics and are required to follow certain restrictions.
3843Overall, these intrinsics represent an extension mechanism for the LLVM
3844language that does not require changing all of the transformations in LLVM when
3845adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
3846
3847<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3848prefix is reserved in LLVM for intrinsic names; thus, function names may not
3849begin with this prefix. Intrinsic functions must always be external functions:
3850you cannot define the body of intrinsic functions. Intrinsic functions may
3851only be used in call or invoke instructions: it is illegal to take the address
3852of an intrinsic function. Additionally, because intrinsic functions are part
3853of the LLVM language, it is required if any are added that they be documented
3854here.</p>
3855
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3856<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
3857a family of functions that perform the same operation but on different data
3858types. Because LLVM can represent over 8 million different integer types,
3859overloading is used commonly to allow an intrinsic function to operate on any
3860integer type. One or more of the argument types or the result type can be
3861overloaded to accept any integer type. Argument types may also be defined as
3862exactly matching a previous argument's type or the result type. This allows an
3863intrinsic function which accepts multiple arguments, but needs all of them to
3864be of the same type, to only be overloaded with respect to a single argument or
3865the result.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3866
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3867<p>Overloaded intrinsics will have the names of its overloaded argument types
3868encoded into its function name, each preceded by a period. Only those types
3869which are overloaded result in a name suffix. Arguments whose type is matched
3870against another type do not. For example, the <tt>llvm.ctpop</tt> function can
3871take an integer of any width and returns an integer of exactly the same integer
3872width. This leads to a family of functions such as
3873<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
3874Only one type, the return type, is overloaded, and only one type suffix is
3875required. Because the argument's type is matched against the return type, it
3876does not require its own name suffix.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3877
3878<p>To learn how to add an intrinsic function, please see the
3879<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
3880</p>
3881
3882</div>
3883
3884<!-- ======================================================================= -->
3885<div class="doc_subsection">
3886 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3887</div>
3888
3889<div class="doc_text">
3890
3891<p>Variable argument support is defined in LLVM with the <a
3892 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
3893intrinsic functions. These functions are related to the similarly
3894named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
3895
3896<p>All of these functions operate on arguments that use a
3897target-specific value type "<tt>va_list</tt>". The LLVM assembly
3898language reference manual does not define what this type is, so all
3899transformations should be prepared to handle these functions regardless of
3900the type used.</p>
3901
3902<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
3903instruction and the variable argument handling intrinsic functions are
3904used.</p>
3905
3906<div class="doc_code">
3907<pre>
3908define i32 @test(i32 %X, ...) {
3909 ; Initialize variable argument processing
3910 %ap = alloca i8*
3911 %ap2 = bitcast i8** %ap to i8*
3912 call void @llvm.va_start(i8* %ap2)
3913
3914 ; Read a single integer argument
3915 %tmp = va_arg i8** %ap, i32
3916
3917 ; Demonstrate usage of llvm.va_copy and llvm.va_end
3918 %aq = alloca i8*
3919 %aq2 = bitcast i8** %aq to i8*
3920 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
3921 call void @llvm.va_end(i8* %aq2)
3922
3923 ; Stop processing of arguments.
3924 call void @llvm.va_end(i8* %ap2)
3925 ret i32 %tmp
3926}
3927
3928declare void @llvm.va_start(i8*)
3929declare void @llvm.va_copy(i8*, i8*)
3930declare void @llvm.va_end(i8*)
3931</pre>
3932</div>
3933
3934</div>
3935
3936<!-- _______________________________________________________________________ -->
3937<div class="doc_subsubsection">
3938 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3939</div>
3940
3941
3942<div class="doc_text">
3943<h5>Syntax:</h5>
3944<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
3945<h5>Overview:</h5>
3946<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3947<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3948href="#i_va_arg">va_arg</a></tt>.</p>
3949
3950<h5>Arguments:</h5>
3951
3952<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3953
3954<h5>Semantics:</h5>
3955
3956<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3957macro available in C. In a target-dependent way, it initializes the
3958<tt>va_list</tt> element to which the argument points, so that the next call to
3959<tt>va_arg</tt> will produce the first variable argument passed to the function.
3960Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3961last argument of the function as the compiler can figure that out.</p>
3962
3963</div>
3964
3965<!-- _______________________________________________________________________ -->
3966<div class="doc_subsubsection">
3967 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3968</div>
3969
3970<div class="doc_text">
3971<h5>Syntax:</h5>
3972<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
3973<h5>Overview:</h5>
3974
3975<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
3976which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
3977or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
3978
3979<h5>Arguments:</h5>
3980
3981<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
3982
3983<h5>Semantics:</h5>
3984
3985<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
3986macro available in C. In a target-dependent way, it destroys the
3987<tt>va_list</tt> element to which the argument points. Calls to <a
3988href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
3989<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
3990<tt>llvm.va_end</tt>.</p>
3991
3992</div>
3993
3994<!-- _______________________________________________________________________ -->
3995<div class="doc_subsubsection">
3996 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3997</div>
3998
3999<div class="doc_text">
4000
4001<h5>Syntax:</h5>
4002
4003<pre>
4004 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
4005</pre>
4006
4007<h5>Overview:</h5>
4008
4009<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
4010from the source argument list to the destination argument list.</p>
4011
4012<h5>Arguments:</h5>
4013
4014<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
4015The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
4016
4017
4018<h5>Semantics:</h5>
4019
4020<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
4021macro available in C. In a target-dependent way, it copies the source
4022<tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
4023intrinsic is necessary because the <tt><a href="#int_va_start">
4024llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
4025example, memory allocation.</p>
4026
4027</div>
4028
4029<!-- ======================================================================= -->
4030<div class="doc_subsection">
4031 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
4032</div>
4033
4034<div class="doc_text">
4035
4036<p>
4037LLVM support for <a href="GarbageCollection.html">Accurate Garbage
4038Collection</a> requires the implementation and generation of these intrinsics.
4039These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
4040stack</a>, as well as garbage collector implementations that require <a
4041href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
4042Front-ends for type-safe garbage collected languages should generate these
4043intrinsics to make use of the LLVM garbage collectors. For more details, see <a
4044href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
4045</p>
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]4046
4047<p>The garbage collection intrinsics only operate on objects in the generic
4048 address space (address space zero).</p>
4049
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4050</div>
4051
4052<!-- _______________________________________________________________________ -->
4053<div class="doc_subsubsection">
4054 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
4055</div>
4056
4057<div class="doc_text">
4058
4059<h5>Syntax:</h5>
4060
4061<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4062 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4063</pre>
4064
4065<h5>Overview:</h5>
4066
4067<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
4068the code generator, and allows some metadata to be associated with it.</p>
4069
4070<h5>Arguments:</h5>
4071
4072<p>The first argument specifies the address of a stack object that contains the
4073root pointer. The second pointer (which must be either a constant or a global
4074value address) contains the meta-data to be associated with the root.</p>
4075
4076<h5>Semantics:</h5>
4077
4078<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
4079location. At compile-time, the code generator generates information to allow
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4080the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
4081intrinsic may only be used in a function which <a href="#gc">specifies a GC
4082algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4083
4084</div>
4085
4086
4087<!-- _______________________________________________________________________ -->
4088<div class="doc_subsubsection">
4089 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
4090</div>
4091
4092<div class="doc_text">
4093
4094<h5>Syntax:</h5>
4095
4096<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4097 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4098</pre>
4099
4100<h5>Overview:</h5>
4101
4102<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
4103locations, allowing garbage collector implementations that require read
4104barriers.</p>
4105
4106<h5>Arguments:</h5>
4107
4108<p>The second argument is the address to read from, which should be an address
4109allocated from the garbage collector. The first object is a pointer to the
4110start of the referenced object, if needed by the language runtime (otherwise
4111null).</p>
4112
4113<h5>Semantics:</h5>
4114
4115<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
4116instruction, but may be replaced with substantially more complex code by the
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4117garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
4118may only be used in a function which <a href="#gc">specifies a GC
4119algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4120
4121</div>
4122
4123
4124<!-- _______________________________________________________________________ -->
4125<div class="doc_subsubsection">
4126 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
4127</div>
4128
4129<div class="doc_text">
4130
4131<h5>Syntax:</h5>
4132
4133<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4134 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4135</pre>
4136
4137<h5>Overview:</h5>
4138
4139<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
4140locations, allowing garbage collector implementations that require write
4141barriers (such as generational or reference counting collectors).</p>
4142
4143<h5>Arguments:</h5>
4144
4145<p>The first argument is the reference to store, the second is the start of the
4146object to store it to, and the third is the address of the field of Obj to
4147store to. If the runtime does not require a pointer to the object, Obj may be
4148null.</p>
4149
4150<h5>Semantics:</h5>
4151
4152<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
4153instruction, but may be replaced with substantially more complex code by the
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4154garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
4155may only be used in a function which <a href="#gc">specifies a GC
4156algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4157
4158</div>
4159
4160
4161
4162<!-- ======================================================================= -->
4163<div class="doc_subsection">
4164 <a name="int_codegen">Code Generator Intrinsics</a>
4165</div>
4166
4167<div class="doc_text">
4168<p>
4169These intrinsics are provided by LLVM to expose special features that may only
4170be implemented with code generator support.
4171</p>
4172
4173</div>
4174
4175<!-- _______________________________________________________________________ -->
4176<div class="doc_subsubsection">
4177 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
4178</div>
4179
4180<div class="doc_text">
4181
4182<h5>Syntax:</h5>
4183<pre>
4184 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
4185</pre>
4186
4187<h5>Overview:</h5>
4188
4189<p>
4190The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
4191target-specific value indicating the return address of the current function
4192or one of its callers.
4193</p>
4194
4195<h5>Arguments:</h5>
4196
4197<p>
4198The argument to this intrinsic indicates which function to return the address
4199for. Zero indicates the calling function, one indicates its caller, etc. The
4200argument is <b>required</b> to be a constant integer value.
4201</p>
4202
4203<h5>Semantics:</h5>
4204
4205<p>
4206The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
4207the return address of the specified call frame, or zero if it cannot be
4208identified. The value returned by this intrinsic is likely to be incorrect or 0
4209for arguments other than zero, so it should only be used for debugging purposes.
4210</p>
4211
4212<p>
4213Note that calling this intrinsic does not prevent function inlining or other
4214aggressive transformations, so the value returned may not be that of the obvious
4215source-language caller.
4216</p>
4217</div>
4218
4219
4220<!-- _______________________________________________________________________ -->
4221<div class="doc_subsubsection">
4222 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
4223</div>
4224
4225<div class="doc_text">
4226
4227<h5>Syntax:</h5>
4228<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4229 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4230</pre>
4231
4232<h5>Overview:</h5>
4233
4234<p>
4235The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
4236target-specific frame pointer value for the specified stack frame.
4237</p>
4238
4239<h5>Arguments:</h5>
4240
4241<p>
4242The argument to this intrinsic indicates which function to return the frame
4243pointer for. Zero indicates the calling function, one indicates its caller,
4244etc. The argument is <b>required</b> to be a constant integer value.
4245</p>
4246
4247<h5>Semantics:</h5>
4248
4249<p>
4250The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
4251the frame address of the specified call frame, or zero if it cannot be
4252identified. The value returned by this intrinsic is likely to be incorrect or 0
4253for arguments other than zero, so it should only be used for debugging purposes.
4254</p>
4255
4256<p>
4257Note that calling this intrinsic does not prevent function inlining or other
4258aggressive transformations, so the value returned may not be that of the obvious
4259source-language caller.
4260</p>
4261</div>
4262
4263<!-- _______________________________________________________________________ -->
4264<div class="doc_subsubsection">
4265 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
4266</div>
4267
4268<div class="doc_text">
4269
4270<h5>Syntax:</h5>
4271<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4272 declare i8 *@llvm.stacksave()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4273</pre>
4274
4275<h5>Overview:</h5>
4276
4277<p>
4278The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
4279the function stack, for use with <a href="#int_stackrestore">
4280<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4281features like scoped automatic variable sized arrays in C99.
4282</p>
4283
4284<h5>Semantics:</h5>
4285
4286<p>
4287This intrinsic returns a opaque pointer value that can be passed to <a
4288href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
4289<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4290<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4291state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4292practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4293that were allocated after the <tt>llvm.stacksave</tt> was executed.
4294</p>
4295
4296</div>
4297
4298<!-- _______________________________________________________________________ -->
4299<div class="doc_subsubsection">
4300 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
4301</div>
4302
4303<div class="doc_text">
4304
4305<h5>Syntax:</h5>
4306<pre>
4307 declare void @llvm.stackrestore(i8 * %ptr)
4308</pre>
4309
4310<h5>Overview:</h5>
4311
4312<p>
4313The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4314the function stack to the state it was in when the corresponding <a
4315href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
4316useful for implementing language features like scoped automatic variable sized
4317arrays in C99.
4318</p>
4319
4320<h5>Semantics:</h5>
4321
4322<p>
4323See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
4324</p>
4325
4326</div>
4327
4328
4329<!-- _______________________________________________________________________ -->
4330<div class="doc_subsubsection">
4331 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
4332</div>
4333
4334<div class="doc_text">
4335
4336<h5>Syntax:</h5>
4337<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4338 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]4339</pre>
4340
4341<h5>Overview:</h5>
4342
4343
4344<p>
4345The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
4346a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4347no
4348effect on the behavior of the program but can change its performance
4349characteristics.
4350</p>
4351
4352<h5>Arguments:</h5>
4353
4354<p>
4355<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4356determining if the fetch should be for a read (0) or write (1), and
4357<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
4358locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
4359<tt>locality</tt> arguments must be constant integers.
4360</p>
4361
4362<h5>Semantics:</h5>
4363
4364<p>
4365This intrinsic does not modify the behavior of the program. In particular,
4366prefetches cannot trap and do not produce a value. On targets that support this
4367intrinsic, the prefetch can provide hints to the processor cache for better
4368performance.
4369</p>
4370
4371</div>
4372
4373<!-- _______________________________________________________________________ -->
4374<div class="doc_subsubsection">
4375 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4376</div>
4377
4378<div class="doc_text">
4379
4380<h5>Syntax:</h5>
4381<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4382 declare void @llvm.pcmarker(i32 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4383</pre>
4384
4385<h5>Overview:</h5>
4386
4387
4388<p>
4389The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4390(PC) in a region of
4391code to simulators and other tools. The method is target specific, but it is
4392expected that the marker will use exported symbols to transmit the PC of the marker.
4393The marker makes no guarantees that it will remain with any specific instruction
4394after optimizations. It is possible that the presence of a marker will inhibit
4395optimizations. The intended use is to be inserted after optimizations to allow
4396correlations of simulation runs.
4397</p>
4398
4399<h5>Arguments:</h5>
4400
4401<p>
4402<tt>id</tt> is a numerical id identifying the marker.
4403</p>
4404
4405<h5>Semantics:</h5>
4406
4407<p>
4408This intrinsic does not modify the behavior of the program. Backends that do not
4409support this intrinisic may ignore it.
4410</p>
4411
4412</div>
4413
4414<!-- _______________________________________________________________________ -->
4415<div class="doc_subsubsection">
4416 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4417</div>
4418
4419<div class="doc_text">
4420
4421<h5>Syntax:</h5>
4422<pre>
4423 declare i64 @llvm.readcyclecounter( )
4424</pre>
4425
4426<h5>Overview:</h5>
4427
4428
4429<p>
4430The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4431counter register (or similar low latency, high accuracy clocks) on those targets
4432that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4433As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4434should only be used for small timings.
4435</p>
4436
4437<h5>Semantics:</h5>
4438
4439<p>
4440When directly supported, reading the cycle counter should not modify any memory.
4441Implementations are allowed to either return a application specific value or a
4442system wide value. On backends without support, this is lowered to a constant 0.
4443</p>
4444
4445</div>
4446
4447<!-- ======================================================================= -->
4448<div class="doc_subsection">
4449 <a name="int_libc">Standard C Library Intrinsics</a>
4450</div>
4451
4452<div class="doc_text">
4453<p>
4454LLVM provides intrinsics for a few important standard C library functions.
4455These intrinsics allow source-language front-ends to pass information about the
4456alignment of the pointer arguments to the code generator, providing opportunity
4457for more efficient code generation.
4458</p>
4459
4460</div>
4461
4462<!-- _______________________________________________________________________ -->
4463<div class="doc_subsubsection">
4464 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4465</div>
4466
4467<div class="doc_text">
4468
4469<h5>Syntax:</h5>
4470<pre>
4471 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4472 i32 &lt;len&gt;, i32 &lt;align&gt;)
4473 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4474 i64 &lt;len&gt;, i32 &lt;align&gt;)
4475</pre>
4476
4477<h5>Overview:</h5>
4478
4479<p>
4480The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4481location to the destination location.
4482</p>
4483
4484<p>
4485Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4486intrinsics do not return a value, and takes an extra alignment argument.
4487</p>
4488
4489<h5>Arguments:</h5>
4490
4491<p>
4492The first argument is a pointer to the destination, the second is a pointer to
4493the source. The third argument is an integer argument
4494specifying the number of bytes to copy, and the fourth argument is the alignment
4495of the source and destination locations.
4496</p>
4497
4498<p>
4499If the call to this intrinisic has an alignment value that is not 0 or 1, then
4500the caller guarantees that both the source and destination pointers are aligned
4501to that boundary.
4502</p>
4503
4504<h5>Semantics:</h5>
4505
4506<p>
4507The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4508location to the destination location, which are not allowed to overlap. It
4509copies "len" bytes of memory over. If the argument is known to be aligned to
4510some boundary, this can be specified as the fourth argument, otherwise it should
4511be set to 0 or 1.
4512</p>
4513</div>
4514
4515
4516<!-- _______________________________________________________________________ -->
4517<div class="doc_subsubsection">
4518 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4519</div>
4520
4521<div class="doc_text">
4522
4523<h5>Syntax:</h5>
4524<pre>
4525 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4526 i32 &lt;len&gt;, i32 &lt;align&gt;)
4527 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4528 i64 &lt;len&gt;, i32 &lt;align&gt;)
4529</pre>
4530
4531<h5>Overview:</h5>
4532
4533<p>
4534The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4535location to the destination location. It is similar to the
Chris Lattnerdba16ea2008-01-06 19:51:52 +0000[diff] [blame]4536'<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to overlap.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4537</p>
4538
4539<p>
4540Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4541intrinsics do not return a value, and takes an extra alignment argument.
4542</p>
4543
4544<h5>Arguments:</h5>
4545
4546<p>
4547The first argument is a pointer to the destination, the second is a pointer to
4548the source. The third argument is an integer argument
4549specifying the number of bytes to copy, and the fourth argument is the alignment
4550of the source and destination locations.
4551</p>
4552
4553<p>
4554If the call to this intrinisic has an alignment value that is not 0 or 1, then
4555the caller guarantees that the source and destination pointers are aligned to
4556that boundary.
4557</p>
4558
4559<h5>Semantics:</h5>
4560
4561<p>
4562The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
4563location to the destination location, which may overlap. It
4564copies "len" bytes of memory over. If the argument is known to be aligned to
4565some boundary, this can be specified as the fourth argument, otherwise it should
4566be set to 0 or 1.
4567</p>
4568</div>
4569
4570
4571<!-- _______________________________________________________________________ -->
4572<div class="doc_subsubsection">
4573 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
4574</div>
4575
4576<div class="doc_text">
4577
4578<h5>Syntax:</h5>
4579<pre>
4580 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4581 i32 &lt;len&gt;, i32 &lt;align&gt;)
4582 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4583 i64 &lt;len&gt;, i32 &lt;align&gt;)
4584</pre>
4585
4586<h5>Overview:</h5>
4587
4588<p>
4589The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
4590byte value.
4591</p>
4592
4593<p>
4594Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4595does not return a value, and takes an extra alignment argument.
4596</p>
4597
4598<h5>Arguments:</h5>
4599
4600<p>
4601The first argument is a pointer to the destination to fill, the second is the
4602byte value to fill it with, the third argument is an integer
4603argument specifying the number of bytes to fill, and the fourth argument is the
4604known alignment of destination location.
4605</p>
4606
4607<p>
4608If the call to this intrinisic has an alignment value that is not 0 or 1, then
4609the caller guarantees that the destination pointer is aligned to that boundary.
4610</p>
4611
4612<h5>Semantics:</h5>
4613
4614<p>
4615The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4616the
4617destination location. If the argument is known to be aligned to some boundary,
4618this can be specified as the fourth argument, otherwise it should be set to 0 or
46191.
4620</p>
4621</div>
4622
4623
4624<!-- _______________________________________________________________________ -->
4625<div class="doc_subsubsection">
4626 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
4627</div>
4628
4629<div class="doc_text">
4630
4631<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4632<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]4633floating point or vector of floating point type. Not all targets support all
4634types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4635<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4636 declare float @llvm.sqrt.f32(float %Val)
4637 declare double @llvm.sqrt.f64(double %Val)
4638 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
4639 declare fp128 @llvm.sqrt.f128(fp128 %Val)
4640 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4641</pre>
4642
4643<h5>Overview:</h5>
4644
4645<p>
4646The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4647returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4648<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4649negative numbers (which allows for better optimization).
4650</p>
4651
4652<h5>Arguments:</h5>
4653
4654<p>
4655The argument and return value are floating point numbers of the same type.
4656</p>
4657
4658<h5>Semantics:</h5>
4659
4660<p>
4661This function returns the sqrt of the specified operand if it is a nonnegative
4662floating point number.
4663</p>
4664</div>
4665
4666<!-- _______________________________________________________________________ -->
4667<div class="doc_subsubsection">
4668 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4669</div>
4670
4671<div class="doc_text">
4672
4673<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4674<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]4675floating point or vector of floating point type. Not all targets support all
4676types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4677<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4678 declare float @llvm.powi.f32(float %Val, i32 %power)
4679 declare double @llvm.powi.f64(double %Val, i32 %power)
4680 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
4681 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
4682 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4683</pre>
4684
4685<h5>Overview:</h5>
4686
4687<p>
4688The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4689specified (positive or negative) power. The order of evaluation of
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4690multiplications is not defined. When a vector of floating point type is
4691used, the second argument remains a scalar integer value.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4692</p>
4693
4694<h5>Arguments:</h5>
4695
4696<p>
4697The second argument is an integer power, and the first is a value to raise to
4698that power.
4699</p>
4700
4701<h5>Semantics:</h5>
4702
4703<p>
4704This function returns the first value raised to the second power with an
4705unspecified sequence of rounding operations.</p>
4706</div>
4707
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4708<!-- _______________________________________________________________________ -->
4709<div class="doc_subsubsection">
4710 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
4711</div>
4712
4713<div class="doc_text">
4714
4715<h5>Syntax:</h5>
4716<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
4717floating point or vector of floating point type. Not all targets support all
4718types however.
4719<pre>
4720 declare float @llvm.sin.f32(float %Val)
4721 declare double @llvm.sin.f64(double %Val)
4722 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
4723 declare fp128 @llvm.sin.f128(fp128 %Val)
4724 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
4725</pre>
4726
4727<h5>Overview:</h5>
4728
4729<p>
4730The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
4731</p>
4732
4733<h5>Arguments:</h5>
4734
4735<p>
4736The argument and return value are floating point numbers of the same type.
4737</p>
4738
4739<h5>Semantics:</h5>
4740
4741<p>
4742This function returns the sine of the specified operand, returning the
4743same values as the libm <tt>sin</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4744conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4745</div>
4746
4747<!-- _______________________________________________________________________ -->
4748<div class="doc_subsubsection">
4749 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
4750</div>
4751
4752<div class="doc_text">
4753
4754<h5>Syntax:</h5>
4755<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
4756floating point or vector of floating point type. Not all targets support all
4757types however.
4758<pre>
4759 declare float @llvm.cos.f32(float %Val)
4760 declare double @llvm.cos.f64(double %Val)
4761 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
4762 declare fp128 @llvm.cos.f128(fp128 %Val)
4763 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
4764</pre>
4765
4766<h5>Overview:</h5>
4767
4768<p>
4769The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
4770</p>
4771
4772<h5>Arguments:</h5>
4773
4774<p>
4775The argument and return value are floating point numbers of the same type.
4776</p>
4777
4778<h5>Semantics:</h5>
4779
4780<p>
4781This function returns the cosine of the specified operand, returning the
4782same values as the libm <tt>cos</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4783conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4784</div>
4785
4786<!-- _______________________________________________________________________ -->
4787<div class="doc_subsubsection">
4788 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
4789</div>
4790
4791<div class="doc_text">
4792
4793<h5>Syntax:</h5>
4794<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
4795floating point or vector of floating point type. Not all targets support all
4796types however.
4797<pre>
4798 declare float @llvm.pow.f32(float %Val, float %Power)
4799 declare double @llvm.pow.f64(double %Val, double %Power)
4800 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
4801 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
4802 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
4803</pre>
4804
4805<h5>Overview:</h5>
4806
4807<p>
4808The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
4809specified (positive or negative) power.
4810</p>
4811
4812<h5>Arguments:</h5>
4813
4814<p>
4815The second argument is a floating point power, and the first is a value to
4816raise to that power.
4817</p>
4818
4819<h5>Semantics:</h5>
4820
4821<p>
4822This function returns the first value raised to the second power,
4823returning the
4824same values as the libm <tt>pow</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4825conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4826</div>
4827
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4828
4829<!-- ======================================================================= -->
4830<div class="doc_subsection">
4831 <a name="int_manip">Bit Manipulation Intrinsics</a>
4832</div>
4833
4834<div class="doc_text">
4835<p>
4836LLVM provides intrinsics for a few important bit manipulation operations.
4837These allow efficient code generation for some algorithms.
4838</p>
4839
4840</div>
4841
4842<!-- _______________________________________________________________________ -->
4843<div class="doc_subsubsection">
4844 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4845</div>
4846
4847<div class="doc_text">
4848
4849<h5>Syntax:</h5>
4850<p>This is an overloaded intrinsic function. You can use bswap on any integer
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4851type that is an even number of bytes (i.e. BitWidth % 16 == 0).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4852<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4853 declare i16 @llvm.bswap.i16(i16 &lt;id&gt;)
4854 declare i32 @llvm.bswap.i32(i32 &lt;id&gt;)
4855 declare i64 @llvm.bswap.i64(i64 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4856</pre>
4857
4858<h5>Overview:</h5>
4859
4860<p>
4861The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
4862values with an even number of bytes (positive multiple of 16 bits). These are
4863useful for performing operations on data that is not in the target's native
4864byte order.
4865</p>
4866
4867<h5>Semantics:</h5>
4868
4869<p>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4870The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4871and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4872intrinsic returns an i32 value that has the four bytes of the input i32
4873swapped, 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]4874i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
4875<tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4876additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
4877</p>
4878
4879</div>
4880
4881<!-- _______________________________________________________________________ -->
4882<div class="doc_subsubsection">
4883 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
4884</div>
4885
4886<div class="doc_text">
4887
4888<h5>Syntax:</h5>
4889<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4890width. Not all targets support all bit widths however.
4891<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4892 declare i8 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4893 declare i16 @llvm.ctpop.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4894 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4895 declare i64 @llvm.ctpop.i64(i64 &lt;src&gt;)
4896 declare i256 @llvm.ctpop.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4897</pre>
4898
4899<h5>Overview:</h5>
4900
4901<p>
4902The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4903value.
4904</p>
4905
4906<h5>Arguments:</h5>
4907
4908<p>
4909The only argument is the value to be counted. The argument may be of any
4910integer type. The return type must match the argument type.
4911</p>
4912
4913<h5>Semantics:</h5>
4914
4915<p>
4916The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4917</p>
4918</div>
4919
4920<!-- _______________________________________________________________________ -->
4921<div class="doc_subsubsection">
4922 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
4923</div>
4924
4925<div class="doc_text">
4926
4927<h5>Syntax:</h5>
4928<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4929integer bit width. Not all targets support all bit widths however.
4930<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4931 declare i8 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4932 declare i16 @llvm.ctlz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4933 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4934 declare i64 @llvm.ctlz.i64(i64 &lt;src&gt;)
4935 declare i256 @llvm.ctlz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4936</pre>
4937
4938<h5>Overview:</h5>
4939
4940<p>
4941The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4942leading zeros in a variable.
4943</p>
4944
4945<h5>Arguments:</h5>
4946
4947<p>
4948The only argument is the value to be counted. The argument may be of any
4949integer type. The return type must match the argument type.
4950</p>
4951
4952<h5>Semantics:</h5>
4953
4954<p>
4955The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4956in a variable. If the src == 0 then the result is the size in bits of the type
4957of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
4958</p>
4959</div>
4960
4961
4962
4963<!-- _______________________________________________________________________ -->
4964<div class="doc_subsubsection">
4965 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
4966</div>
4967
4968<div class="doc_text">
4969
4970<h5>Syntax:</h5>
4971<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4972integer bit width. Not all targets support all bit widths however.
4973<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4974 declare i8 @llvm.cttz.i8 (i8 &lt;src&gt;)
4975 declare i16 @llvm.cttz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4976 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4977 declare i64 @llvm.cttz.i64(i64 &lt;src&gt;)
4978 declare i256 @llvm.cttz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4979</pre>
4980
4981<h5>Overview:</h5>
4982
4983<p>
4984The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4985trailing zeros.
4986</p>
4987
4988<h5>Arguments:</h5>
4989
4990<p>
4991The only argument is the value to be counted. The argument may be of any
4992integer type. The return type must match the argument type.
4993</p>
4994
4995<h5>Semantics:</h5>
4996
4997<p>
4998The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4999in a variable. If the src == 0 then the result is the size in bits of the type
5000of src. For example, <tt>llvm.cttz(2) = 1</tt>.
5001</p>
5002</div>
5003
5004<!-- _______________________________________________________________________ -->
5005<div class="doc_subsubsection">
5006 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
5007</div>
5008
5009<div class="doc_text">
5010
5011<h5>Syntax:</h5>
5012<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
5013on any integer bit width.
5014<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5015 declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
5016 declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5017</pre>
5018
5019<h5>Overview:</h5>
5020<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
5021range of bits from an integer value and returns them in the same bit width as
5022the original value.</p>
5023
5024<h5>Arguments:</h5>
5025<p>The first argument, <tt>%val</tt> and the result may be integer types of
5026any bit width but they must have the same bit width. The second and third
5027arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
5028
5029<h5>Semantics:</h5>
5030<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
5031of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
5032<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
5033operates in forward mode.</p>
5034<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
5035right by <tt>%loBit</tt> bits and then ANDing it with a mask with
5036only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
5037<ol>
5038 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
5039 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
5040 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
5041 to determine the number of bits to retain.</li>
5042 <li>A mask of the retained bits is created by shifting a -1 value.</li>
5043 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
5044</ol>
5045<p>In reverse mode, a similar computation is made except that the bits are
5046returned in the reverse order. So, for example, if <tt>X</tt> has the value
5047<tt>i16 0x0ACF (101011001111)</tt> and we apply
5048<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
5049<tt>i16 0x0026 (000000100110)</tt>.</p>
5050</div>
5051
5052<div class="doc_subsubsection">
5053 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
5054</div>
5055
5056<div class="doc_text">
5057
5058<h5>Syntax:</h5>
5059<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
5060on any integer bit width.
5061<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5062 declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
5063 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]5064</pre>
5065
5066<h5>Overview:</h5>
5067<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
5068of bits in an integer value with another integer value. It returns the integer
5069with the replaced bits.</p>
5070
5071<h5>Arguments:</h5>
5072<p>The first argument, <tt>%val</tt> and the result may be integer types of
5073any bit width but they must have the same bit width. <tt>%val</tt> is the value
5074whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
5075integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
5076type since they specify only a bit index.</p>
5077
5078<h5>Semantics:</h5>
5079<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
5080of operation: forwards and reverse. If <tt>%lo</tt> is greater than
5081<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
5082operates in forward mode.</p>
5083<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
5084truncating it down to the size of the replacement area or zero extending it
5085up to that size.</p>
5086<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
5087are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
5088in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
5089to the <tt>%hi</tt>th bit.
5090<p>In reverse mode, a similar computation is made except that the bits are
5091reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
5092<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
5093<h5>Examples:</h5>
5094<pre>
5095 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
5096 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0xFF0F
5097 llvm.part.set(0xFFFF, 1, 7, 4) -&gt; 0xFF8F
5098 llvm.part.set(0xFFFF, F, 8, 3) -&gt; 0xFFE7
5099 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
5100</pre>
5101</div>
5102
5103<!-- ======================================================================= -->
5104<div class="doc_subsection">
5105 <a name="int_debugger">Debugger Intrinsics</a>
5106</div>
5107
5108<div class="doc_text">
5109<p>
5110The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
5111are described in the <a
5112href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
5113Debugging</a> document.
5114</p>
5115</div>
5116
5117
5118<!-- ======================================================================= -->
5119<div class="doc_subsection">
5120 <a name="int_eh">Exception Handling Intrinsics</a>
5121</div>
5122
5123<div class="doc_text">
5124<p> The LLVM exception handling intrinsics (which all start with
5125<tt>llvm.eh.</tt> prefix), are described in the <a
5126href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
5127Handling</a> document. </p>
5128</div>
5129
5130<!-- ======================================================================= -->
5131<div class="doc_subsection">
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5132 <a name="int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5133</div>
5134
5135<div class="doc_text">
5136<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5137 This intrinsic makes it possible to excise one parameter, marked with
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5138 the <tt>nest</tt> attribute, from a function. The result is a callable
5139 function pointer lacking the nest parameter - the caller does not need
5140 to provide a value for it. Instead, the value to use is stored in
5141 advance in a "trampoline", a block of memory usually allocated
5142 on the stack, which also contains code to splice the nest value into the
5143 argument list. This is used to implement the GCC nested function address
5144 extension.
5145</p>
5146<p>
5147 For example, if the function is
5148 <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]5149 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]5150<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5151 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
5152 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
5153 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
5154 %fp = bitcast i8* %p to i32 (i32, i32)*
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5155</pre>
Bill Wendlinge262b4c2007-09-22 09:23:55 +0000[diff] [blame]5156 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
5157 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5158</div>
5159
5160<!-- _______________________________________________________________________ -->
5161<div class="doc_subsubsection">
5162 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
5163</div>
5164<div class="doc_text">
5165<h5>Syntax:</h5>
5166<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5167declare 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]5168</pre>
5169<h5>Overview:</h5>
5170<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5171 This fills the memory pointed to by <tt>tramp</tt> with code
5172 and returns a function pointer suitable for executing it.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5173</p>
5174<h5>Arguments:</h5>
5175<p>
5176 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
5177 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
5178 and sufficiently aligned block of memory; this memory is written to by the
Duncan Sands35012212007-08-22 23:39:54 +0000[diff] [blame]5179 intrinsic. Note that the size and the alignment are target-specific - LLVM
5180 currently provides no portable way of determining them, so a front-end that
5181 generates this intrinsic needs to have some target-specific knowledge.
5182 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]5183</p>
5184<h5>Semantics:</h5>
5185<p>
5186 The block of memory pointed to by <tt>tramp</tt> is filled with target
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5187 dependent code, turning it into a function. A pointer to this function is
5188 returned, but needs to be bitcast to an
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5189 <a href="#int_trampoline">appropriate function pointer type</a>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5190 before being called. The new function's signature is the same as that of
5191 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
5192 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
5193 of pointer type. Calling the new function is equivalent to calling
5194 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
5195 missing <tt>nest</tt> argument. If, after calling
5196 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
5197 modified, then the effect of any later call to the returned function pointer is
5198 undefined.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5199</p>
5200</div>
5201
5202<!-- ======================================================================= -->
5203<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5204 <a name="int_general">General Intrinsics</a>
5205</div>
5206
5207<div class="doc_text">
5208<p> This class of intrinsics is designed to be generic and has
5209no specific purpose. </p>
5210</div>
5211
5212<!-- _______________________________________________________________________ -->
5213<div class="doc_subsubsection">
5214 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
5215</div>
5216
5217<div class="doc_text">
5218
5219<h5>Syntax:</h5>
5220<pre>
5221 declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5222</pre>
5223
5224<h5>Overview:</h5>
5225
5226<p>
5227The '<tt>llvm.var.annotation</tt>' intrinsic
5228</p>
5229
5230<h5>Arguments:</h5>
5231
5232<p>
5233The first argument is a pointer to a value, the second is a pointer to a
5234global string, the third is a pointer to a global string which is the source
5235file name, and the last argument is the line number.
5236</p>
5237
5238<h5>Semantics:</h5>
5239
5240<p>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame^]5241This intrinsic allows annotation of local variables with arbitrary strings.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5242This can be useful for special purpose optimizations that want to look for these
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame^]5243annotations. These have no other defined use, they are ignored by code
5244generation and optimization.
5245</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5246</div>
5247
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5248<!-- _______________________________________________________________________ -->
5249<div class="doc_subsubsection">
Tanya Lattnerc9869b12007-09-21 23:57:59 +0000[diff] [blame]5250 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5251</div>
5252
5253<div class="doc_text">
5254
5255<h5>Syntax:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5256<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
5257any integer bit width.
5258</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5259<pre>
Tanya Lattner09161fe2007-09-22 00:03:01 +0000[diff] [blame]5260 declare i8 @llvm.annotation.i8(i8 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5261 declare i16 @llvm.annotation.i16(i16 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5262 declare i32 @llvm.annotation.i32(i32 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5263 declare i64 @llvm.annotation.i64(i64 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5264 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]5265</pre>
5266
5267<h5>Overview:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5268
5269<p>
5270The '<tt>llvm.annotation</tt>' intrinsic.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5271</p>
5272
5273<h5>Arguments:</h5>
5274
5275<p>
5276The first argument is an integer value (result of some expression),
5277the second is a pointer to a global string, the third is a pointer to a global
5278string which is the source file name, and the last argument is the line number.
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5279It returns the value of the first argument.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5280</p>
5281
5282<h5>Semantics:</h5>
5283
5284<p>
5285This intrinsic allows annotations to be put on arbitrary expressions
5286with arbitrary strings. This can be useful for special purpose optimizations
5287that want to look for these annotations. These have no other defined use, they
5288are ignored by code generation and optimization.
5289</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5290
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame^]5291<!-- _______________________________________________________________________ -->
5292<div class="doc_subsubsection">
5293 <a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
5294</div>
5295
5296<div class="doc_text">
5297
5298<h5>Syntax:</h5>
5299<pre>
5300 declare void @llvm.trap()
5301</pre>
5302
5303<h5>Overview:</h5>
5304
5305<p>
5306The '<tt>llvm.trap</tt>' intrinsic
5307</p>
5308
5309<h5>Arguments:</h5>
5310
5311<p>
5312None
5313</p>
5314
5315<h5>Semantics:</h5>
5316
5317<p>
5318This intrinsics is lowered to the target dependent trap instruction. If the
5319target does not have a trap instruction, this intrinsic will be lowered to the
5320call of the abort() function.
5321</p>
5322</div>
5323
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5324<!-- *********************************************************************** -->
5325<hr>
5326<address>
5327 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
5328 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]5330 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5331
5332 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
5333 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
5334 Last modified: $Date$
5335</address>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]5336
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5338</html>