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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>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]147 <li><a href="#i_getresult">'<tt>getresult</tt>' Instruction</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]148 </ol>
149 </li>
150 </ol>
151 </li>
152 <li><a href="#intrinsics">Intrinsic Functions</a>
153 <ol>
154 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
155 <ol>
156 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
157 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
158 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
159 </ol>
160 </li>
161 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
162 <ol>
163 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
164 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
165 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
166 </ol>
167 </li>
168 <li><a href="#int_codegen">Code Generator Intrinsics</a>
169 <ol>
170 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
171 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
172 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
173 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
174 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
175 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
176 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
177 </ol>
178 </li>
179 <li><a href="#int_libc">Standard C Library Intrinsics</a>
180 <ol>
181 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
182 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
183 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
184 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
185 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]186 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
187 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
188 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]189 </ol>
190 </li>
191 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
192 <ol>
193 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
194 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
195 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
196 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
197 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
198 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
199 </ol>
200 </li>
201 <li><a href="#int_debugger">Debugger intrinsics</a></li>
202 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]203 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]204 <ol>
205 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]206 </ol>
207 </li>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]208 <li><a href="#int_atomics">Atomic intrinsics</a>
209 <ol>
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]210 <li><a href="#int_memory_barrier"><tt>llvm.memory_barrier</tt></a></li>
211 <li><a href="#int_atomic_lcs"><tt>llvm.atomic.lcs</tt></a></li>
212 <li><a href="#int_atomic_las"><tt>llvm.atomic.las</tt></a></li>
213 <li><a href="#int_atomic_swap"><tt>llvm.atomic.swap</tt></a></li>
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]214 </ol>
215 </li>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]216 <li><a href="#int_general">General intrinsics</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]217 <ol>
Reid Spencerb043f672007-07-20 19:59:11 +0000[diff] [blame]218 <li><a href="#int_var_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]219 <tt>llvm.var.annotation</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]220 <li><a href="#int_annotation">
Tanya Lattner51369f32007-09-22 00:01:26 +0000[diff] [blame]221 <tt>llvm.annotation.*</tt>' Intrinsic</a></li>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]222 <li><a href="#int_trap">
223 <tt>llvm.trap</tt>' Intrinsic</a></li>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]224 </ol>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]225 </li>
226 </ol>
227 </li>
228</ol>
229
230<div class="doc_author">
231 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
232 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
233</div>
234
235<!-- *********************************************************************** -->
236<div class="doc_section"> <a name="abstract">Abstract </a></div>
237<!-- *********************************************************************** -->
238
239<div class="doc_text">
240<p>This document is a reference manual for the LLVM assembly language.
241LLVM is an SSA based representation that provides type safety,
242low-level operations, flexibility, and the capability of representing
243'all' high-level languages cleanly. It is the common code
244representation used throughout all phases of the LLVM compilation
245strategy.</p>
246</div>
247
248<!-- *********************************************************************** -->
249<div class="doc_section"> <a name="introduction">Introduction</a> </div>
250<!-- *********************************************************************** -->
251
252<div class="doc_text">
253
254<p>The LLVM code representation is designed to be used in three
255different forms: as an in-memory compiler IR, as an on-disk bitcode
256representation (suitable for fast loading by a Just-In-Time compiler),
257and as a human readable assembly language representation. This allows
258LLVM to provide a powerful intermediate representation for efficient
259compiler transformations and analysis, while providing a natural means
260to debug and visualize the transformations. The three different forms
261of LLVM are all equivalent. This document describes the human readable
262representation and notation.</p>
263
264<p>The LLVM representation aims to be light-weight and low-level
265while being expressive, typed, and extensible at the same time. It
266aims to be a "universal IR" of sorts, by being at a low enough level
267that high-level ideas may be cleanly mapped to it (similar to how
268microprocessors are "universal IR's", allowing many source languages to
269be mapped to them). By providing type information, LLVM can be used as
270the target of optimizations: for example, through pointer analysis, it
271can be proven that a C automatic variable is never accessed outside of
272the current function... allowing it to be promoted to a simple SSA
273value instead of a memory location.</p>
274
275</div>
276
277<!-- _______________________________________________________________________ -->
278<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
279
280<div class="doc_text">
281
282<p>It is important to note that this document describes 'well formed'
283LLVM assembly language. There is a difference between what the parser
284accepts and what is considered 'well formed'. For example, the
285following instruction is syntactically okay, but not well formed:</p>
286
287<div class="doc_code">
288<pre>
289%x = <a href="#i_add">add</a> i32 1, %x
290</pre>
291</div>
292
293<p>...because the definition of <tt>%x</tt> does not dominate all of
294its uses. The LLVM infrastructure provides a verification pass that may
295be used to verify that an LLVM module is well formed. This pass is
296automatically run by the parser after parsing input assembly and by
297the optimizer before it outputs bitcode. The violations pointed out
298by the verifier pass indicate bugs in transformation passes or input to
299the parser.</p>
300</div>
301
Chris Lattnera83fdc02007-10-03 17:34:29 +0000[diff] [blame]302<!-- Describe the typesetting conventions here. -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]303
304<!-- *********************************************************************** -->
305<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
306<!-- *********************************************************************** -->
307
308<div class="doc_text">
309
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]310 <p>LLVM identifiers come in two basic types: global and local. Global
311 identifiers (functions, global variables) begin with the @ character. Local
312 identifiers (register names, types) begin with the % character. Additionally,
313 there are three different formats for identifiers, for different purposes:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]314
315<ol>
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]316 <li>Named values are represented as a string of characters with their prefix.
317 For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
318 regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]319 Identifiers which require other characters in their names can be surrounded
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]320 with quotes. In this way, anything except a <tt>&quot;</tt> character can
321 be used in a named value.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]322
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]323 <li>Unnamed values are represented as an unsigned numeric value with their
324 prefix. For example, %12, @2, %44.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]325
326 <li>Constants, which are described in a <a href="#constants">section about
327 constants</a>, below.</li>
328</ol>
329
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]330<p>LLVM requires that values start with a prefix for two reasons: Compilers
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]331don't need to worry about name clashes with reserved words, and the set of
332reserved words may be expanded in the future without penalty. Additionally,
333unnamed identifiers allow a compiler to quickly come up with a temporary
334variable without having to avoid symbol table conflicts.</p>
335
336<p>Reserved words in LLVM are very similar to reserved words in other
337languages. There are keywords for different opcodes
338('<tt><a href="#i_add">add</a></tt>',
339 '<tt><a href="#i_bitcast">bitcast</a></tt>',
340 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
341href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
342and others. These reserved words cannot conflict with variable names, because
Reid Spencerc8245b02007-08-07 14:34:28 +0000[diff] [blame]343none of them start with a prefix character ('%' or '@').</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]344
345<p>Here is an example of LLVM code to multiply the integer variable
346'<tt>%X</tt>' by 8:</p>
347
348<p>The easy way:</p>
349
350<div class="doc_code">
351<pre>
352%result = <a href="#i_mul">mul</a> i32 %X, 8
353</pre>
354</div>
355
356<p>After strength reduction:</p>
357
358<div class="doc_code">
359<pre>
360%result = <a href="#i_shl">shl</a> i32 %X, i8 3
361</pre>
362</div>
363
364<p>And the hard way:</p>
365
366<div class="doc_code">
367<pre>
368<a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
369<a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
370%result = <a href="#i_add">add</a> i32 %1, %1
371</pre>
372</div>
373
374<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
375important lexical features of LLVM:</p>
376
377<ol>
378
379 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
380 line.</li>
381
382 <li>Unnamed temporaries are created when the result of a computation is not
383 assigned to a named value.</li>
384
385 <li>Unnamed temporaries are numbered sequentially</li>
386
387</ol>
388
389<p>...and it also shows a convention that we follow in this document. When
390demonstrating instructions, we will follow an instruction with a comment that
391defines the type and name of value produced. Comments are shown in italic
392text.</p>
393
394</div>
395
396<!-- *********************************************************************** -->
397<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
398<!-- *********************************************************************** -->
399
400<!-- ======================================================================= -->
401<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
402</div>
403
404<div class="doc_text">
405
406<p>LLVM programs are composed of "Module"s, each of which is a
407translation unit of the input programs. Each module consists of
408functions, global variables, and symbol table entries. Modules may be
409combined together with the LLVM linker, which merges function (and
410global variable) definitions, resolves forward declarations, and merges
411symbol table entries. Here is an example of the "hello world" module:</p>
412
413<div class="doc_code">
414<pre><i>; Declare the string constant as a global constant...</i>
415<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
416 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
417
418<i>; External declaration of the puts function</i>
419<a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
420
421<i>; Definition of main function</i>
422define i32 @main() { <i>; i32()* </i>
423 <i>; Convert [13x i8 ]* to i8 *...</i>
424 %cast210 = <a
425 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
426
427 <i>; Call puts function to write out the string to stdout...</i>
428 <a
429 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
430 <a
431 href="#i_ret">ret</a> i32 0<br>}<br>
432</pre>
433</div>
434
435<p>This example is made up of a <a href="#globalvars">global variable</a>
436named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
437function, and a <a href="#functionstructure">function definition</a>
438for "<tt>main</tt>".</p>
439
440<p>In general, a module is made up of a list of global values,
441where both functions and global variables are global values. Global values are
442represented by a pointer to a memory location (in this case, a pointer to an
443array of char, and a pointer to a function), and have one of the following <a
444href="#linkage">linkage types</a>.</p>
445
446</div>
447
448<!-- ======================================================================= -->
449<div class="doc_subsection">
450 <a name="linkage">Linkage Types</a>
451</div>
452
453<div class="doc_text">
454
455<p>
456All Global Variables and Functions have one of the following types of linkage:
457</p>
458
459<dl>
460
461 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
462
463 <dd>Global values with internal linkage are only directly accessible by
464 objects in the current module. In particular, linking code into a module with
465 an internal global value may cause the internal to be renamed as necessary to
466 avoid collisions. Because the symbol is internal to the module, all
467 references can be updated. This corresponds to the notion of the
468 '<tt>static</tt>' keyword in C.
469 </dd>
470
471 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
472
473 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
474 the same name when linkage occurs. This is typically used to implement
475 inline functions, templates, or other code which must be generated in each
476 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
477 allowed to be discarded.
478 </dd>
479
480 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
481
482 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
483 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
484 used for globals that may be emitted in multiple translation units, but that
485 are not guaranteed to be emitted into every translation unit that uses them.
486 One example of this are common globals in C, such as "<tt>int X;</tt>" at
487 global scope.
488 </dd>
489
490 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
491
492 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
493 pointer to array type. When two global variables with appending linkage are
494 linked together, the two global arrays are appended together. This is the
495 LLVM, typesafe, equivalent of having the system linker append together
496 "sections" with identical names when .o files are linked.
497 </dd>
498
499 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
500 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
501 until linked, if not linked, the symbol becomes null instead of being an
502 undefined reference.
503 </dd>
504
505 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
506
507 <dd>If none of the above identifiers are used, the global is externally
508 visible, meaning that it participates in linkage and can be used to resolve
509 external symbol references.
510 </dd>
511</dl>
512
513 <p>
514 The next two types of linkage are targeted for Microsoft Windows platform
515 only. They are designed to support importing (exporting) symbols from (to)
516 DLLs.
517 </p>
518
519 <dl>
520 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
521
522 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
523 or variable via a global pointer to a pointer that is set up by the DLL
524 exporting the symbol. On Microsoft Windows targets, the pointer name is
525 formed by combining <code>_imp__</code> and the function or variable name.
526 </dd>
527
528 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
529
530 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
531 pointer to a pointer in a DLL, so that it can be referenced with the
532 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
533 name is formed by combining <code>_imp__</code> and the function or variable
534 name.
535 </dd>
536
537</dl>
538
539<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
540variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
541variable and was linked with this one, one of the two would be renamed,
542preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
543external (i.e., lacking any linkage declarations), they are accessible
544outside of the current module.</p>
545<p>It is illegal for a function <i>declaration</i>
546to have any linkage type other than "externally visible", <tt>dllimport</tt>,
547or <tt>extern_weak</tt>.</p>
548<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
549linkages.
550</div>
551
552<!-- ======================================================================= -->
553<div class="doc_subsection">
554 <a name="callingconv">Calling Conventions</a>
555</div>
556
557<div class="doc_text">
558
559<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
560and <a href="#i_invoke">invokes</a> can all have an optional calling convention
561specified for the call. The calling convention of any pair of dynamic
562caller/callee must match, or the behavior of the program is undefined. The
563following calling conventions are supported by LLVM, and more may be added in
564the future:</p>
565
566<dl>
567 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
568
569 <dd>This calling convention (the default if no other calling convention is
570 specified) matches the target C calling conventions. This calling convention
571 supports varargs function calls and tolerates some mismatch in the declared
572 prototype and implemented declaration of the function (as does normal C).
573 </dd>
574
575 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
576
577 <dd>This calling convention attempts to make calls as fast as possible
578 (e.g. by passing things in registers). This calling convention allows the
579 target to use whatever tricks it wants to produce fast code for the target,
580 without having to conform to an externally specified ABI. Implementations of
581 this convention should allow arbitrary tail call optimization to be supported.
582 This calling convention does not support varargs and requires the prototype of
583 all callees to exactly match the prototype of the function definition.
584 </dd>
585
586 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
587
588 <dd>This calling convention attempts to make code in the caller as efficient
589 as possible under the assumption that the call is not commonly executed. As
590 such, these calls often preserve all registers so that the call does not break
591 any live ranges in the caller side. This calling convention does not support
592 varargs and requires the prototype of all callees to exactly match the
593 prototype of the function definition.
594 </dd>
595
596 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
597
598 <dd>Any calling convention may be specified by number, allowing
599 target-specific calling conventions to be used. Target specific calling
600 conventions start at 64.
601 </dd>
602</dl>
603
604<p>More calling conventions can be added/defined on an as-needed basis, to
605support pascal conventions or any other well-known target-independent
606convention.</p>
607
608</div>
609
610<!-- ======================================================================= -->
611<div class="doc_subsection">
612 <a name="visibility">Visibility Styles</a>
613</div>
614
615<div class="doc_text">
616
617<p>
618All Global Variables and Functions have one of the following visibility styles:
619</p>
620
621<dl>
622 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
623
624 <dd>On ELF, default visibility means that the declaration is visible to other
625 modules and, in shared libraries, means that the declared entity may be
626 overridden. On Darwin, default visibility means that the declaration is
627 visible to other modules. Default visibility corresponds to "external
628 linkage" in the language.
629 </dd>
630
631 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
632
633 <dd>Two declarations of an object with hidden visibility refer to the same
634 object if they are in the same shared object. Usually, hidden visibility
635 indicates that the symbol will not be placed into the dynamic symbol table,
636 so no other module (executable or shared library) can reference it
637 directly.
638 </dd>
639
640 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
641
642 <dd>On ELF, protected visibility indicates that the symbol will be placed in
643 the dynamic symbol table, but that references within the defining module will
644 bind to the local symbol. That is, the symbol cannot be overridden by another
645 module.
646 </dd>
647</dl>
648
649</div>
650
651<!-- ======================================================================= -->
652<div class="doc_subsection">
653 <a name="globalvars">Global Variables</a>
654</div>
655
656<div class="doc_text">
657
658<p>Global variables define regions of memory allocated at compilation time
659instead of run-time. Global variables may optionally be initialized, may have
660an explicit section to be placed in, and may have an optional explicit alignment
661specified. A variable may be defined as "thread_local", which means that it
662will not be shared by threads (each thread will have a separated copy of the
663variable). A variable may be defined as a global "constant," which indicates
664that the contents of the variable will <b>never</b> be modified (enabling better
665optimization, allowing the global data to be placed in the read-only section of
666an executable, etc). Note that variables that need runtime initialization
667cannot be marked "constant" as there is a store to the variable.</p>
668
669<p>
670LLVM explicitly allows <em>declarations</em> of global variables to be marked
671constant, even if the final definition of the global is not. This capability
672can be used to enable slightly better optimization of the program, but requires
673the language definition to guarantee that optimizations based on the
674'constantness' are valid for the translation units that do not include the
675definition.
676</p>
677
678<p>As SSA values, global variables define pointer values that are in
679scope (i.e. they dominate) all basic blocks in the program. Global
680variables always define a pointer to their "content" type because they
681describe a region of memory, and all memory objects in LLVM are
682accessed through pointers.</p>
683
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]684<p>A global variable may be declared to reside in a target-specifc numbered
685address space. For targets that support them, address spaces may affect how
686optimizations are performed and/or what target instructions are used to access
Christopher Lamb20a39e92007-12-12 08:44:39 +0000[diff] [blame]687the variable. The default address space is zero. The address space qualifier
688must precede any other attributes.</p>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]689
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]690<p>LLVM allows an explicit section to be specified for globals. If the target
691supports it, it will emit globals to the section specified.</p>
692
693<p>An explicit alignment may be specified for a global. If not present, or if
694the alignment is set to zero, the alignment of the global is set by the target
695to whatever it feels convenient. If an explicit alignment is specified, the
696global is forced to have at least that much alignment. All alignments must be
697a power of 2.</p>
698
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]699<p>For example, the following defines a global in a numbered address space with
700an initializer, section, and alignment:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]701
702<div class="doc_code">
703<pre>
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]704@G = constant float 1.0 addrspace(5), section "foo", align 4
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]705</pre>
706</div>
707
708</div>
709
710
711<!-- ======================================================================= -->
712<div class="doc_subsection">
713 <a name="functionstructure">Functions</a>
714</div>
715
716<div class="doc_text">
717
718<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
719an optional <a href="#linkage">linkage type</a>, an optional
720<a href="#visibility">visibility style</a>, an optional
721<a href="#callingconv">calling convention</a>, a return type, an optional
722<a href="#paramattrs">parameter attribute</a> for the return type, a function
723name, a (possibly empty) argument list (each with optional
724<a href="#paramattrs">parameter attributes</a>), an optional section, an
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]725optional alignment, an optional <a href="#gc">garbage collector name</a>, an
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]726opening curly brace, a list of basic blocks, and a closing curly brace.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]727
728LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
729optional <a href="#linkage">linkage type</a>, an optional
730<a href="#visibility">visibility style</a>, an optional
731<a href="#callingconv">calling convention</a>, a return type, an optional
732<a href="#paramattrs">parameter attribute</a> for the return type, a function
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]733name, a possibly empty list of arguments, an optional alignment, and an optional
Gordon Henriksend606f5b2007-12-10 03:30:21 +0000[diff] [blame]734<a href="#gc">garbage collector name</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]735
736<p>A function definition contains a list of basic blocks, forming the CFG for
737the function. Each basic block may optionally start with a label (giving the
738basic block a symbol table entry), contains a list of instructions, and ends
739with a <a href="#terminators">terminator</a> instruction (such as a branch or
740function return).</p>
741
742<p>The first basic block in a function is special in two ways: it is immediately
743executed on entrance to the function, and it is not allowed to have predecessor
744basic blocks (i.e. there can not be any branches to the entry block of a
745function). Because the block can have no predecessors, it also cannot have any
746<a href="#i_phi">PHI nodes</a>.</p>
747
748<p>LLVM allows an explicit section to be specified for functions. If the target
749supports it, it will emit functions to the section specified.</p>
750
751<p>An explicit alignment may be specified for a function. If not present, or if
752the alignment is set to zero, the alignment of the function is set by the target
753to whatever it feels convenient. If an explicit alignment is specified, the
754function is forced to have at least that much alignment. All alignments must be
755a power of 2.</p>
756
757</div>
758
759
760<!-- ======================================================================= -->
761<div class="doc_subsection">
762 <a name="aliasstructure">Aliases</a>
763</div>
764<div class="doc_text">
765 <p>Aliases act as "second name" for the aliasee value (which can be either
Anton Korobeynikov96822812008-03-22 08:36:14 +0000[diff] [blame]766 function, global variable, another alias or bitcast of global value). Aliases
767 may have an optional <a href="#linkage">linkage type</a>, and an
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]768 optional <a href="#visibility">visibility style</a>.</p>
769
770 <h5>Syntax:</h5>
771
772<div class="doc_code">
773<pre>
774@&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
775</pre>
776</div>
777
778</div>
779
780
781
782<!-- ======================================================================= -->
783<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
784<div class="doc_text">
785 <p>The return type and each parameter of a function type may have a set of
786 <i>parameter attributes</i> associated with them. Parameter attributes are
787 used to communicate additional information about the result or parameters of
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]788 a function. Parameter attributes are considered to be part of the function,
789 not of the function type, so functions with different parameter attributes
790 can have the same function type.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]791
792 <p>Parameter attributes are simple keywords that follow the type specified. If
793 multiple parameter attributes are needed, they are space separated. For
794 example:</p>
795
796<div class="doc_code">
797<pre>
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]798declare i32 @printf(i8* noalias , ...) nounwind
799declare i32 @atoi(i8*) nounwind readonly
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]800</pre>
801</div>
802
Duncan Sandsf5588dc2007-11-27 13:23:08 +0000[diff] [blame]803 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
804 <tt>readonly</tt>) come immediately after the argument list.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]805
806 <p>Currently, only the following parameter attributes are defined:</p>
807 <dl>
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]808 <dt><tt>zeroext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]809 <dd>This indicates that the parameter should be zero extended just before
810 a call to this function.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]811
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]812 <dt><tt>signext</tt></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]813 <dd>This indicates that the parameter should be sign extended just before
814 a call to this function.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]815
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]816 <dt><tt>inreg</tt></dt>
817 <dd>This indicates that the parameter should be placed in register (if
818 possible) during assembling function call. Support for this attribute is
819 target-specific</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]820
821 <dt><tt>byval</tt></dt>
Chris Lattner04c86182008-01-15 04:34:22 +0000[diff] [blame]822 <dd>This indicates that the pointer parameter should really be passed by
823 value to the function. The attribute implies that a hidden copy of the
824 pointee is made between the caller and the callee, so the callee is unable
825 to modify the value in the callee. This attribute is only valid on llvm
826 pointer arguments. It is generally used to pass structs and arrays by
827 value, but is also valid on scalars (even though this is silly).</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]828
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]829 <dt><tt>sret</tt></dt>
Duncan Sands616cc032008-02-18 04:19:38 +0000[diff] [blame]830 <dd>This indicates that the pointer parameter specifies the address of a
831 structure that is the return value of the function in the source program.
Duncan Sandsef0e9e42008-03-17 12:17:41 +0000[diff] [blame]832 Loads and stores to the structure are assumed not to trap.
Duncan Sands616cc032008-02-18 04:19:38 +0000[diff] [blame]833 May only be applied to the first parameter.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]834
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]835 <dt><tt>noalias</tt></dt>
Owen Andersonc4fc4cd2008-02-18 04:09:01 +0000[diff] [blame]836 <dd>This indicates that the parameter does not alias any global or any other
837 parameter. The caller is responsible for ensuring that this is the case,
838 usually by placing the value in a stack allocation.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]839
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]840 <dt><tt>noreturn</tt></dt>
841 <dd>This function attribute indicates that the function never returns. This
842 indicates to LLVM that every call to this function should be treated as if
843 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Chris Lattner275e6be2008-01-11 06:20:47 +0000[diff] [blame]844
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]845 <dt><tt>nounwind</tt></dt>
Duncan Sandsef0e9e42008-03-17 12:17:41 +0000[diff] [blame]846 <dd>This function attribute indicates that no exceptions unwind out of the
847 function. Usually this is because the function makes no use of exceptions,
848 but it may also be that the function catches any exceptions thrown when
849 executing it.</dd>
850
Duncan Sands4ee46812007-07-27 19:57:41 +0000[diff] [blame]851 <dt><tt>nest</tt></dt>
852 <dd>This indicates that the parameter can be excised using the
853 <a href="#int_trampoline">trampoline intrinsics</a>.</dd>
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]854 <dt><tt>readonly</tt></dt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]855 <dd>This function attribute indicates that the function has no side-effects
Duncan Sands13e13f82007-11-22 20:23:04 +0000[diff] [blame]856 except for producing a return value or throwing an exception. The value
857 returned must only depend on the function arguments and/or global variables.
858 It may use values obtained by dereferencing pointers.</dd>
859 <dt><tt>readnone</tt></dt>
860 <dd>A <tt>readnone</tt> function has the same restrictions as a <tt>readonly</tt>
Duncan Sandsd69c0e62007-11-14 21:14:02 +0000[diff] [blame]861 function, but in addition it is not allowed to dereference any pointer arguments
862 or global variables.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]863 </dl>
864
865</div>
866
867<!-- ======================================================================= -->
868<div class="doc_subsection">
Gordon Henriksen13fe5e32007-12-10 03:18:06 +0000[diff] [blame]869 <a name="gc">Garbage Collector Names</a>
870</div>
871
872<div class="doc_text">
873<p>Each function may specify a garbage collector name, which is simply a
874string.</p>
875
876<div class="doc_code"><pre
877>define void @f() gc "name" { ...</pre></div>
878
879<p>The compiler declares the supported values of <i>name</i>. Specifying a
880collector which will cause the compiler to alter its output in order to support
881the named garbage collection algorithm.</p>
882</div>
883
884<!-- ======================================================================= -->
885<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]886 <a name="moduleasm">Module-Level Inline Assembly</a>
887</div>
888
889<div class="doc_text">
890<p>
891Modules may contain "module-level inline asm" blocks, which corresponds to the
892GCC "file scope inline asm" blocks. These blocks are internally concatenated by
893LLVM and treated as a single unit, but may be separated in the .ll file if
894desired. The syntax is very simple:
895</p>
896
897<div class="doc_code">
898<pre>
899module asm "inline asm code goes here"
900module asm "more can go here"
901</pre>
902</div>
903
904<p>The strings can contain any character by escaping non-printable characters.
905 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
906 for the number.
907</p>
908
909<p>
910 The inline asm code is simply printed to the machine code .s file when
911 assembly code is generated.
912</p>
913</div>
914
915<!-- ======================================================================= -->
916<div class="doc_subsection">
917 <a name="datalayout">Data Layout</a>
918</div>
919
920<div class="doc_text">
921<p>A module may specify a target specific data layout string that specifies how
922data is to be laid out in memory. The syntax for the data layout is simply:</p>
923<pre> target datalayout = "<i>layout specification</i>"</pre>
924<p>The <i>layout specification</i> consists of a list of specifications
925separated by the minus sign character ('-'). Each specification starts with a
926letter and may include other information after the letter to define some
927aspect of the data layout. The specifications accepted are as follows: </p>
928<dl>
929 <dt><tt>E</tt></dt>
930 <dd>Specifies that the target lays out data in big-endian form. That is, the
931 bits with the most significance have the lowest address location.</dd>
932 <dt><tt>e</tt></dt>
933 <dd>Specifies that hte target lays out data in little-endian form. That is,
934 the bits with the least significance have the lowest address location.</dd>
935 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
936 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
937 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
938 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
939 too.</dd>
940 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
941 <dd>This specifies the alignment for an integer type of a given bit
942 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
943 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
944 <dd>This specifies the alignment for a vector type of a given bit
945 <i>size</i>.</dd>
946 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
947 <dd>This specifies the alignment for a floating point type of a given bit
948 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
949 (double).</dd>
950 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
951 <dd>This specifies the alignment for an aggregate type of a given bit
952 <i>size</i>.</dd>
953</dl>
954<p>When constructing the data layout for a given target, LLVM starts with a
955default set of specifications which are then (possibly) overriden by the
956specifications in the <tt>datalayout</tt> keyword. The default specifications
957are given in this list:</p>
958<ul>
959 <li><tt>E</tt> - big endian</li>
960 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
961 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
962 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
963 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
964 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
965 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
966 alignment of 64-bits</li>
967 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
968 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
969 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
970 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
971 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
972</ul>
973<p>When llvm is determining the alignment for a given type, it uses the
974following rules:
975<ol>
976 <li>If the type sought is an exact match for one of the specifications, that
977 specification is used.</li>
978 <li>If no match is found, and the type sought is an integer type, then the
979 smallest integer type that is larger than the bitwidth of the sought type is
980 used. If none of the specifications are larger than the bitwidth then the the
981 largest integer type is used. For example, given the default specifications
982 above, the i7 type will use the alignment of i8 (next largest) while both
983 i65 and i256 will use the alignment of i64 (largest specified).</li>
984 <li>If no match is found, and the type sought is a vector type, then the
985 largest vector type that is smaller than the sought vector type will be used
986 as a fall back. This happens because <128 x double> can be implemented in
987 terms of 64 <2 x double>, for example.</li>
988</ol>
989</div>
990
991<!-- *********************************************************************** -->
992<div class="doc_section"> <a name="typesystem">Type System</a> </div>
993<!-- *********************************************************************** -->
994
995<div class="doc_text">
996
997<p>The LLVM type system is one of the most important features of the
998intermediate representation. Being typed enables a number of
999optimizations to be performed on the IR directly, without having to do
1000extra analyses on the side before the transformation. A strong type
1001system makes it easier to read the generated code and enables novel
1002analyses and transformations that are not feasible to perform on normal
1003three address code representations.</p>
1004
1005</div>
1006
1007<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1008<div class="doc_subsection"> <a name="t_classifications">Type
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1009Classifications</a> </div>
1010<div class="doc_text">
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1011<p>The types fall into a few useful
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1012classifications:</p>
1013
1014<table border="1" cellspacing="0" cellpadding="4">
1015 <tbody>
1016 <tr><th>Classification</th><th>Types</th></tr>
1017 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1018 <td><a href="#t_integer">integer</a></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1019 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1020 </tr>
1021 <tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1022 <td><a href="#t_floating">floating point</a></td>
1023 <td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1024 </tr>
1025 <tr>
1026 <td><a name="t_firstclass">first class</a></td>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1027 <td><a href="#t_integer">integer</a>,
1028 <a href="#t_floating">floating point</a>,
1029 <a href="#t_pointer">pointer</a>,
1030 <a href="#t_vector">vector</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1031 </td>
1032 </tr>
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1033 <tr>
1034 <td><a href="#t_primitive">primitive</a></td>
1035 <td><a href="#t_label">label</a>,
1036 <a href="#t_void">void</a>,
1037 <a href="#t_integer">integer</a>,
1038 <a href="#t_floating">floating point</a>.</td>
1039 </tr>
1040 <tr>
1041 <td><a href="#t_derived">derived</a></td>
1042 <td><a href="#t_integer">integer</a>,
1043 <a href="#t_array">array</a>,
1044 <a href="#t_function">function</a>,
1045 <a href="#t_pointer">pointer</a>,
1046 <a href="#t_struct">structure</a>,
1047 <a href="#t_pstruct">packed structure</a>,
1048 <a href="#t_vector">vector</a>,
1049 <a href="#t_opaque">opaque</a>.
1050 </tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1051 </tbody>
1052</table>
1053
1054<p>The <a href="#t_firstclass">first class</a> types are perhaps the
1055most important. Values of these types are the only ones which can be
1056produced by instructions, passed as arguments, or used as operands to
1057instructions. This means that all structures and arrays must be
1058manipulated either by pointer or by component.</p>
1059</div>
1060
1061<!-- ======================================================================= -->
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1062<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1063
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1064<div class="doc_text">
1065<p>The primitive types are the fundamental building blocks of the LLVM
1066system.</p>
1067
Chris Lattner86437612008-01-04 04:34:14 +0000[diff] [blame]1068</div>
1069
Chris Lattner488772f2008-01-04 04:32:38 +0000[diff] [blame]1070<!-- _______________________________________________________________________ -->
1071<div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
1072
1073<div class="doc_text">
1074 <table>
1075 <tbody>
1076 <tr><th>Type</th><th>Description</th></tr>
1077 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
1078 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
1079 <tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
1080 <tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
1081 <tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
1082 </tbody>
1083 </table>
1084</div>
1085
1086<!-- _______________________________________________________________________ -->
1087<div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
1088
1089<div class="doc_text">
1090<h5>Overview:</h5>
1091<p>The void type does not represent any value and has no size.</p>
1092
1093<h5>Syntax:</h5>
1094
1095<pre>
1096 void
1097</pre>
1098</div>
1099
1100<!-- _______________________________________________________________________ -->
1101<div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
1102
1103<div class="doc_text">
1104<h5>Overview:</h5>
1105<p>The label type represents code labels.</p>
1106
1107<h5>Syntax:</h5>
1108
1109<pre>
1110 label
1111</pre>
1112</div>
1113
1114
1115<!-- ======================================================================= -->
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1116<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1117
1118<div class="doc_text">
1119
1120<p>The real power in LLVM comes from the derived types in the system.
1121This is what allows a programmer to represent arrays, functions,
1122pointers, and other useful types. Note that these derived types may be
1123recursive: For example, it is possible to have a two dimensional array.</p>
1124
1125</div>
1126
1127<!-- _______________________________________________________________________ -->
1128<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1129
1130<div class="doc_text">
1131
1132<h5>Overview:</h5>
1133<p>The integer type is a very simple derived type that simply specifies an
1134arbitrary bit width for the integer type desired. Any bit width from 1 bit to
11352^23-1 (about 8 million) can be specified.</p>
1136
1137<h5>Syntax:</h5>
1138
1139<pre>
1140 iN
1141</pre>
1142
1143<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1144value.</p>
1145
1146<h5>Examples:</h5>
1147<table class="layout">
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]1148 <tbody>
1149 <tr>
1150 <td><tt>i1</tt></td>
1151 <td>a single-bit integer.</td>
1152 </tr><tr>
1153 <td><tt>i32</tt></td>
1154 <td>a 32-bit integer.</td>
1155 </tr><tr>
1156 <td><tt>i1942652</tt></td>
1157 <td>a really big integer of over 1 million bits.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1158 </tr>
Chris Lattner251ab812007-12-18 06:18:21 +0000[diff] [blame]1159 </tbody>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1160</table>
1161</div>
1162
1163<!-- _______________________________________________________________________ -->
1164<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1165
1166<div class="doc_text">
1167
1168<h5>Overview:</h5>
1169
1170<p>The array type is a very simple derived type that arranges elements
1171sequentially in memory. The array type requires a size (number of
1172elements) and an underlying data type.</p>
1173
1174<h5>Syntax:</h5>
1175
1176<pre>
1177 [&lt;# elements&gt; x &lt;elementtype&gt;]
1178</pre>
1179
1180<p>The number of elements is a constant integer value; elementtype may
1181be any type with a size.</p>
1182
1183<h5>Examples:</h5>
1184<table class="layout">
1185 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1186 <td class="left"><tt>[40 x i32]</tt></td>
1187 <td class="left">Array of 40 32-bit integer values.</td>
1188 </tr>
1189 <tr class="layout">
1190 <td class="left"><tt>[41 x i32]</tt></td>
1191 <td class="left">Array of 41 32-bit integer values.</td>
1192 </tr>
1193 <tr class="layout">
1194 <td class="left"><tt>[4 x i8]</tt></td>
1195 <td class="left">Array of 4 8-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1196 </tr>
1197</table>
1198<p>Here are some examples of multidimensional arrays:</p>
1199<table class="layout">
1200 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1201 <td class="left"><tt>[3 x [4 x i32]]</tt></td>
1202 <td class="left">3x4 array of 32-bit integer values.</td>
1203 </tr>
1204 <tr class="layout">
1205 <td class="left"><tt>[12 x [10 x float]]</tt></td>
1206 <td class="left">12x10 array of single precision floating point values.</td>
1207 </tr>
1208 <tr class="layout">
1209 <td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
1210 <td class="left">2x3x4 array of 16-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1211 </tr>
1212</table>
1213
1214<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1215length array. Normally, accesses past the end of an array are undefined in
1216LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1217As a special case, however, zero length arrays are recognized to be variable
1218length. This allows implementation of 'pascal style arrays' with the LLVM
1219type "{ i32, [0 x float]}", for example.</p>
1220
1221</div>
1222
1223<!-- _______________________________________________________________________ -->
1224<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1225<div class="doc_text">
1226<h5>Overview:</h5>
1227<p>The function type can be thought of as a function signature. It
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1228consists of a return type and a list of formal parameter types. The
Devang Pateld5404c02008-03-24 20:52:42 +0000[diff] [blame]1229return type of a function type is a scalar type or a void type or a struct type.
1230If the return type is a struct type then all struct elements must be of first
Devang Patel6dddba22008-03-24 18:10:52 +0000[diff] [blame]1231class types. Function types are usually used to build virtual function tables
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1232(which are structures of pointers to functions), for indirect function
1233calls, and when defining a function.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1234
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1235<h5>Syntax:</h5>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1236<pre> &lt;returntype list&gt; (&lt;parameter list&gt;)<br></pre>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1237<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
1238specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1239which indicates that the function takes a variable number of arguments.
1240Variable argument functions can access their arguments with the <a
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1241 href="#int_varargs">variable argument handling intrinsic</a> functions.
1242'<tt>&lt;returntype list&gt;</tt>' is a comma-separated list of
1243<a href="#t_firstclass">first class</a> type specifiers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1244<h5>Examples:</h5>
1245<table class="layout">
1246 <tr class="layout">
1247 <td class="left"><tt>i32 (i32)</tt></td>
1248 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1249 </td>
1250 </tr><tr class="layout">
Reid Spencerf234bed2007-07-19 23:13:04 +0000[diff] [blame]1251 <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1252 </tt></td>
1253 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1254 an <tt>i16</tt> that should be sign extended and a
1255 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1256 <tt>float</tt>.
1257 </td>
1258 </tr><tr class="layout">
1259 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1260 <td class="left">A vararg function that takes at least one
1261 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1262 which returns an integer. This is the signature for <tt>printf</tt> in
1263 LLVM.
1264 </td>
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1265 </tr><tr class="layout">
1266 <td class="left"><tt>{i32, i32} (i32)</tt></td>
Devang Patel6dddba22008-03-24 18:10:52 +0000[diff] [blame]1267 <td class="left">A function taking an <tt>i32></tt>, returning two
1268 <tt> i32 </tt> values as an aggregate of type <tt>{ i32, i32 }</tt>
Devang Pateld4ba41d2008-03-24 05:35:41 +0000[diff] [blame]1269 </td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1270 </tr>
1271</table>
1272
1273</div>
1274<!-- _______________________________________________________________________ -->
1275<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1276<div class="doc_text">
1277<h5>Overview:</h5>
1278<p>The structure type is used to represent a collection of data members
1279together in memory. The packing of the field types is defined to match
1280the ABI of the underlying processor. The elements of a structure may
1281be any type that has a size.</p>
1282<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1283and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1284field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1285instruction.</p>
1286<h5>Syntax:</h5>
1287<pre> { &lt;type list&gt; }<br></pre>
1288<h5>Examples:</h5>
1289<table class="layout">
1290 <tr class="layout">
1291 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1292 <td class="left">A triple of three <tt>i32</tt> values</td>
1293 </tr><tr class="layout">
1294 <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
1295 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1296 second element is a <a href="#t_pointer">pointer</a> to a
1297 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1298 an <tt>i32</tt>.</td>
1299 </tr>
1300</table>
1301</div>
1302
1303<!-- _______________________________________________________________________ -->
1304<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1305</div>
1306<div class="doc_text">
1307<h5>Overview:</h5>
1308<p>The packed structure type is used to represent a collection of data members
1309together in memory. There is no padding between fields. Further, the alignment
1310of a packed structure is 1 byte. The elements of a packed structure may
1311be any type that has a size.</p>
1312<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1313and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1314field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1315instruction.</p>
1316<h5>Syntax:</h5>
1317<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1318<h5>Examples:</h5>
1319<table class="layout">
1320 <tr class="layout">
1321 <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
1322 <td class="left">A triple of three <tt>i32</tt> values</td>
1323 </tr><tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1324 <td class="left"><tt>&lt; { float, i32 (i32)* } &gt;</tt></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1325 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1326 second element is a <a href="#t_pointer">pointer</a> to a
1327 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1328 an <tt>i32</tt>.</td>
1329 </tr>
1330</table>
1331</div>
1332
1333<!-- _______________________________________________________________________ -->
1334<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1335<div class="doc_text">
1336<h5>Overview:</h5>
1337<p>As in many languages, the pointer type represents a pointer or
Christopher Lambdd0049d2007-12-11 09:31:00 +0000[diff] [blame]1338reference to another object, which must live in memory. Pointer types may have
1339an optional address space attribute defining the target-specific numbered
1340address space where the pointed-to object resides. The default address space is
1341zero.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1342<h5>Syntax:</h5>
1343<pre> &lt;type&gt; *<br></pre>
1344<h5>Examples:</h5>
1345<table class="layout">
1346 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1347 <td class="left"><tt>[4x i32]*</tt></td>
1348 <td class="left">A <a href="#t_pointer">pointer</a> to <a
1349 href="#t_array">array</a> of four <tt>i32</tt> values.</td>
1350 </tr>
1351 <tr class="layout">
1352 <td class="left"><tt>i32 (i32 *) *</tt></td>
1353 <td class="left"> A <a href="#t_pointer">pointer</a> to a <a
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1354 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1355 <tt>i32</tt>.</td>
1356 </tr>
1357 <tr class="layout">
1358 <td class="left"><tt>i32 addrspace(5)*</tt></td>
1359 <td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
1360 that resides in address space #5.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1361 </tr>
1362</table>
1363</div>
1364
1365<!-- _______________________________________________________________________ -->
1366<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1367<div class="doc_text">
1368
1369<h5>Overview:</h5>
1370
1371<p>A vector type is a simple derived type that represents a vector
1372of elements. Vector types are used when multiple primitive data
1373are operated in parallel using a single instruction (SIMD).
1374A vector type requires a size (number of
1375elements) and an underlying primitive data type. Vectors must have a power
1376of two length (1, 2, 4, 8, 16 ...). Vector types are
1377considered <a href="#t_firstclass">first class</a>.</p>
1378
1379<h5>Syntax:</h5>
1380
1381<pre>
1382 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1383</pre>
1384
1385<p>The number of elements is a constant integer value; elementtype may
1386be any integer or floating point type.</p>
1387
1388<h5>Examples:</h5>
1389
1390<table class="layout">
1391 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1392 <td class="left"><tt>&lt;4 x i32&gt;</tt></td>
1393 <td class="left">Vector of 4 32-bit integer values.</td>
1394 </tr>
1395 <tr class="layout">
1396 <td class="left"><tt>&lt;8 x float&gt;</tt></td>
1397 <td class="left">Vector of 8 32-bit floating-point values.</td>
1398 </tr>
1399 <tr class="layout">
1400 <td class="left"><tt>&lt;2 x i64&gt;</tt></td>
1401 <td class="left">Vector of 2 64-bit integer values.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1402 </tr>
1403</table>
1404</div>
1405
1406<!-- _______________________________________________________________________ -->
1407<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1408<div class="doc_text">
1409
1410<h5>Overview:</h5>
1411
1412<p>Opaque types are used to represent unknown types in the system. This
Gordon Henriksenda0706e2007-10-14 00:34:53 +0000[diff] [blame]1413corresponds (for example) to the C notion of a forward declared structure type.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1414In LLVM, opaque types can eventually be resolved to any type (not just a
1415structure type).</p>
1416
1417<h5>Syntax:</h5>
1418
1419<pre>
1420 opaque
1421</pre>
1422
1423<h5>Examples:</h5>
1424
1425<table class="layout">
1426 <tr class="layout">
Chris Lattner7311d222007-12-19 05:04:11 +0000[diff] [blame]1427 <td class="left"><tt>opaque</tt></td>
1428 <td class="left">An opaque type.</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1429 </tr>
1430</table>
1431</div>
1432
1433
1434<!-- *********************************************************************** -->
1435<div class="doc_section"> <a name="constants">Constants</a> </div>
1436<!-- *********************************************************************** -->
1437
1438<div class="doc_text">
1439
1440<p>LLVM has several different basic types of constants. This section describes
1441them all and their syntax.</p>
1442
1443</div>
1444
1445<!-- ======================================================================= -->
1446<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1447
1448<div class="doc_text">
1449
1450<dl>
1451 <dt><b>Boolean constants</b></dt>
1452
1453 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1454 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1455 </dd>
1456
1457 <dt><b>Integer constants</b></dt>
1458
1459 <dd>Standard integers (such as '4') are constants of the <a
1460 href="#t_integer">integer</a> type. Negative numbers may be used with
1461 integer types.
1462 </dd>
1463
1464 <dt><b>Floating point constants</b></dt>
1465
1466 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1467 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame^]1468 notation (see below). The assembler requires the exact decimal value of
1469 a floating-point constant. For example, the assembler accepts 1.25 but
1470 rejects 1.3 because 1.3 is a repeating decimal in binary. Floating point
1471 constants must have a <a href="#t_floating">floating point</a> type. </dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1472
1473 <dt><b>Null pointer constants</b></dt>
1474
1475 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1476 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1477
1478</dl>
1479
1480<p>The one non-intuitive notation for constants is the optional hexadecimal form
1481of floating point constants. For example, the form '<tt>double
14820x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
14834.5e+15</tt>'. The only time hexadecimal floating point constants are required
1484(and the only time that they are generated by the disassembler) is when a
1485floating point constant must be emitted but it cannot be represented as a
1486decimal floating point number. For example, NaN's, infinities, and other
1487special values are represented in their IEEE hexadecimal format so that
1488assembly and disassembly do not cause any bits to change in the constants.</p>
1489
1490</div>
1491
1492<!-- ======================================================================= -->
1493<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1494</div>
1495
1496<div class="doc_text">
1497<p>Aggregate constants arise from aggregation of simple constants
1498and smaller aggregate constants.</p>
1499
1500<dl>
1501 <dt><b>Structure constants</b></dt>
1502
1503 <dd>Structure constants are represented with notation similar to structure
1504 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner6c8de962007-12-25 20:34:52 +0000[diff] [blame]1505 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
1506 where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1507 must have <a href="#t_struct">structure type</a>, and the number and
1508 types of elements must match those specified by the type.
1509 </dd>
1510
1511 <dt><b>Array constants</b></dt>
1512
1513 <dd>Array constants are represented with notation similar to array type
1514 definitions (a comma separated list of elements, surrounded by square brackets
1515 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1516 constants must have <a href="#t_array">array type</a>, and the number and
1517 types of elements must match those specified by the type.
1518 </dd>
1519
1520 <dt><b>Vector constants</b></dt>
1521
1522 <dd>Vector constants are represented with notation similar to vector type
1523 definitions (a comma separated list of elements, surrounded by
1524 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1525 i32 11, i32 74, i32 100 &gt;</tt>". Vector constants must have <a
1526 href="#t_vector">vector type</a>, and the number and types of elements must
1527 match those specified by the type.
1528 </dd>
1529
1530 <dt><b>Zero initialization</b></dt>
1531
1532 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1533 value to zero of <em>any</em> type, including scalar and aggregate types.
1534 This is often used to avoid having to print large zero initializers (e.g. for
1535 large arrays) and is always exactly equivalent to using explicit zero
1536 initializers.
1537 </dd>
1538</dl>
1539
1540</div>
1541
1542<!-- ======================================================================= -->
1543<div class="doc_subsection">
1544 <a name="globalconstants">Global Variable and Function Addresses</a>
1545</div>
1546
1547<div class="doc_text">
1548
1549<p>The addresses of <a href="#globalvars">global variables</a> and <a
1550href="#functionstructure">functions</a> are always implicitly valid (link-time)
1551constants. These constants are explicitly referenced when the <a
1552href="#identifiers">identifier for the global</a> is used and always have <a
1553href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1554file:</p>
1555
1556<div class="doc_code">
1557<pre>
1558@X = global i32 17
1559@Y = global i32 42
1560@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1561</pre>
1562</div>
1563
1564</div>
1565
1566<!-- ======================================================================= -->
1567<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1568<div class="doc_text">
1569 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1570 no specific value. Undefined values may be of any type and be used anywhere
1571 a constant is permitted.</p>
1572
1573 <p>Undefined values indicate to the compiler that the program is well defined
1574 no matter what value is used, giving the compiler more freedom to optimize.
1575 </p>
1576</div>
1577
1578<!-- ======================================================================= -->
1579<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1580</div>
1581
1582<div class="doc_text">
1583
1584<p>Constant expressions are used to allow expressions involving other constants
1585to be used as constants. Constant expressions may be of any <a
1586href="#t_firstclass">first class</a> type and may involve any LLVM operation
1587that does not have side effects (e.g. load and call are not supported). The
1588following is the syntax for constant expressions:</p>
1589
1590<dl>
1591 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1592 <dd>Truncate a constant to another type. The bit size of CST must be larger
1593 than the bit size of TYPE. Both types must be integers.</dd>
1594
1595 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1596 <dd>Zero extend a constant to another type. The bit size of CST must be
1597 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1598
1599 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1600 <dd>Sign extend a constant to another type. The bit size of CST must be
1601 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1602
1603 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1604 <dd>Truncate a floating point constant to another floating point type. The
1605 size of CST must be larger than the size of TYPE. Both types must be
1606 floating point.</dd>
1607
1608 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1609 <dd>Floating point extend a constant to another type. The size of CST must be
1610 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1611
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]1612 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1613 <dd>Convert a floating point constant to the corresponding unsigned integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1614 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1615 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1616 of the same number of elements. If the value won't fit in the integer type,
1617 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1618
1619 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1620 <dd>Convert a floating point constant to the corresponding signed integer
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1621 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1622 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1623 of the same number of elements. If the value won't fit in the integer type,
1624 the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1625
1626 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1627 <dd>Convert an unsigned integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1628 constant. TYPE must be a scalar or vector floating point type. CST must be of
1629 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1630 of the same number of elements. If the value won't fit in the floating point
1631 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1632
1633 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
1634 <dd>Convert a signed integer constant to the corresponding floating point
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]1635 constant. TYPE must be a scalar or vector floating point type. CST must be of
1636 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1637 of the same number of elements. If the value won't fit in the floating point
1638 type, the results are undefined.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1639
1640 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1641 <dd>Convert a pointer typed constant to the corresponding integer constant
1642 TYPE must be an integer type. CST must be of pointer type. The CST value is
1643 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1644
1645 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1646 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1647 pointer type. CST must be of integer type. The CST value is zero extended,
1648 truncated, or unchanged to make it fit in a pointer size. This one is
1649 <i>really</i> dangerous!</dd>
1650
1651 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
1652 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1653 identical (same number of bits). The conversion is done as if the CST value
1654 was stored to memory and read back as TYPE. In other words, no bits change
1655 with this operator, just the type. This can be used for conversion of
1656 vector types to any other type, as long as they have the same bit width. For
1657 pointers it is only valid to cast to another pointer type.
1658 </dd>
1659
1660 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1661
1662 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1663 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1664 instruction, the index list may have zero or more indexes, which are required
1665 to make sense for the type of "CSTPTR".</dd>
1666
1667 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1668
1669 <dd>Perform the <a href="#i_select">select operation</a> on
1670 constants.</dd>
1671
1672 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1673 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1674
1675 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1676 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
1677
1678 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1679
1680 <dd>Perform the <a href="#i_extractelement">extractelement
1681 operation</a> on constants.
1682
1683 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1684
1685 <dd>Perform the <a href="#i_insertelement">insertelement
1686 operation</a> on constants.</dd>
1687
1688
1689 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1690
1691 <dd>Perform the <a href="#i_shufflevector">shufflevector
1692 operation</a> on constants.</dd>
1693
1694 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1695
1696 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1697 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
1698 binary</a> operations. The constraints on operands are the same as those for
1699 the corresponding instruction (e.g. no bitwise operations on floating point
1700 values are allowed).</dd>
1701</dl>
1702</div>
1703
1704<!-- *********************************************************************** -->
1705<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1706<!-- *********************************************************************** -->
1707
1708<!-- ======================================================================= -->
1709<div class="doc_subsection">
1710<a name="inlineasm">Inline Assembler Expressions</a>
1711</div>
1712
1713<div class="doc_text">
1714
1715<p>
1716LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1717Module-Level Inline Assembly</a>) through the use of a special value. This
1718value represents the inline assembler as a string (containing the instructions
1719to emit), a list of operand constraints (stored as a string), and a flag that
1720indicates whether or not the inline asm expression has side effects. An example
1721inline assembler expression is:
1722</p>
1723
1724<div class="doc_code">
1725<pre>
1726i32 (i32) asm "bswap $0", "=r,r"
1727</pre>
1728</div>
1729
1730<p>
1731Inline assembler expressions may <b>only</b> be used as the callee operand of
1732a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1733</p>
1734
1735<div class="doc_code">
1736<pre>
1737%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
1738</pre>
1739</div>
1740
1741<p>
1742Inline asms with side effects not visible in the constraint list must be marked
1743as having side effects. This is done through the use of the
1744'<tt>sideeffect</tt>' keyword, like so:
1745</p>
1746
1747<div class="doc_code">
1748<pre>
1749call void asm sideeffect "eieio", ""()
1750</pre>
1751</div>
1752
1753<p>TODO: The format of the asm and constraints string still need to be
1754documented here. Constraints on what can be done (e.g. duplication, moving, etc
1755need to be documented).
1756</p>
1757
1758</div>
1759
1760<!-- *********************************************************************** -->
1761<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1762<!-- *********************************************************************** -->
1763
1764<div class="doc_text">
1765
1766<p>The LLVM instruction set consists of several different
1767classifications of instructions: <a href="#terminators">terminator
1768instructions</a>, <a href="#binaryops">binary instructions</a>,
1769<a href="#bitwiseops">bitwise binary instructions</a>, <a
1770 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1771instructions</a>.</p>
1772
1773</div>
1774
1775<!-- ======================================================================= -->
1776<div class="doc_subsection"> <a name="terminators">Terminator
1777Instructions</a> </div>
1778
1779<div class="doc_text">
1780
1781<p>As mentioned <a href="#functionstructure">previously</a>, every
1782basic block in a program ends with a "Terminator" instruction, which
1783indicates which block should be executed after the current block is
1784finished. These terminator instructions typically yield a '<tt>void</tt>'
1785value: they produce control flow, not values (the one exception being
1786the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
1787<p>There are six different terminator instructions: the '<a
1788 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1789instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
1790the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1791 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1792 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
1793
1794</div>
1795
1796<!-- _______________________________________________________________________ -->
1797<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1798Instruction</a> </div>
1799<div class="doc_text">
1800<h5>Syntax:</h5>
1801<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
1802 ret void <i>; Return from void function</i>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1803 ret &lt;type&gt; &lt;value&gt;, &lt;type&gt; &lt;value&gt; <i>; Return two values from a non-void function </i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1804</pre>
1805<h5>Overview:</h5>
1806<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1807value) from a function back to the caller.</p>
1808<p>There are two forms of the '<tt>ret</tt>' instruction: one that
1809returns a value and then causes control flow, and one that just causes
1810control flow to occur.</p>
1811<h5>Arguments:</h5>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1812<p>The '<tt>ret</tt>' instruction may return one or multiple values. The
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1813type of each return value must be a '<a href="#t_firstclass">first class</a>'
1814 type. Note that a function is not <a href="#wellformed">well formed</a>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1815if there exists a '<tt>ret</tt>' instruction inside of the function that
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1816returns values that do not match the return type of the function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1817<h5>Semantics:</h5>
1818<p>When the '<tt>ret</tt>' instruction is executed, control flow
1819returns back to the calling function's context. If the caller is a "<a
1820 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
1821the instruction after the call. If the caller was an "<a
1822 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1823at the beginning of the "normal" destination block. If the instruction
1824returns a value, that value shall set the call or invoke instruction's
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1825return value. If the instruction returns multiple values then these
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1826values can only be accessed through a '<a href="#i_getresult"><tt>getresult</tt>
1827</a>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1828<h5>Example:</h5>
1829<pre> ret i32 5 <i>; Return an integer value of 5</i>
1830 ret void <i>; Return from a void function</i>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1831 ret i32 4, i8 2 <i>; Return two values 4 and 2 </i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1832</pre>
1833</div>
1834<!-- _______________________________________________________________________ -->
1835<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
1836<div class="doc_text">
1837<h5>Syntax:</h5>
1838<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
1839</pre>
1840<h5>Overview:</h5>
1841<p>The '<tt>br</tt>' instruction is used to cause control flow to
1842transfer to a different basic block in the current function. There are
1843two forms of this instruction, corresponding to a conditional branch
1844and an unconditional branch.</p>
1845<h5>Arguments:</h5>
1846<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1847single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
1848unconditional form of the '<tt>br</tt>' instruction takes a single
1849'<tt>label</tt>' value as a target.</p>
1850<h5>Semantics:</h5>
1851<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
1852argument is evaluated. If the value is <tt>true</tt>, control flows
1853to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1854control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
1855<h5>Example:</h5>
1856<pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq, i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
1857 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
1858</div>
1859<!-- _______________________________________________________________________ -->
1860<div class="doc_subsubsection">
1861 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1862</div>
1863
1864<div class="doc_text">
1865<h5>Syntax:</h5>
1866
1867<pre>
1868 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1869</pre>
1870
1871<h5>Overview:</h5>
1872
1873<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1874several different places. It is a generalization of the '<tt>br</tt>'
1875instruction, allowing a branch to occur to one of many possible
1876destinations.</p>
1877
1878
1879<h5>Arguments:</h5>
1880
1881<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1882comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1883an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1884table is not allowed to contain duplicate constant entries.</p>
1885
1886<h5>Semantics:</h5>
1887
1888<p>The <tt>switch</tt> instruction specifies a table of values and
1889destinations. When the '<tt>switch</tt>' instruction is executed, this
1890table is searched for the given value. If the value is found, control flow is
1891transfered to the corresponding destination; otherwise, control flow is
1892transfered to the default destination.</p>
1893
1894<h5>Implementation:</h5>
1895
1896<p>Depending on properties of the target machine and the particular
1897<tt>switch</tt> instruction, this instruction may be code generated in different
1898ways. For example, it could be generated as a series of chained conditional
1899branches or with a lookup table.</p>
1900
1901<h5>Example:</h5>
1902
1903<pre>
1904 <i>; Emulate a conditional br instruction</i>
1905 %Val = <a href="#i_zext">zext</a> i1 %value to i32
1906 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
1907
1908 <i>; Emulate an unconditional br instruction</i>
1909 switch i32 0, label %dest [ ]
1910
1911 <i>; Implement a jump table:</i>
1912 switch i32 %val, label %otherwise [ i32 0, label %onzero
1913 i32 1, label %onone
1914 i32 2, label %ontwo ]
1915</pre>
1916</div>
1917
1918<!-- _______________________________________________________________________ -->
1919<div class="doc_subsubsection">
1920 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1921</div>
1922
1923<div class="doc_text">
1924
1925<h5>Syntax:</h5>
1926
1927<pre>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]1928 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; &lt;function ptr val&gt;(&lt;function args&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1929 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
1930</pre>
1931
1932<h5>Overview:</h5>
1933
1934<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1935function, with the possibility of control flow transfer to either the
1936'<tt>normal</tt>' label or the
1937'<tt>exception</tt>' label. If the callee function returns with the
1938"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1939"normal" label. If the callee (or any indirect callees) returns with the "<a
1940href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]1941continued at the dynamically nearest "exception" label. If the callee function
Devang Patelec8a5b02008-03-11 05:51:59 +0000[diff] [blame]1942returns multiple values then individual return values are only accessible through
1943a '<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1944
1945<h5>Arguments:</h5>
1946
1947<p>This instruction requires several arguments:</p>
1948
1949<ol>
1950 <li>
1951 The optional "cconv" marker indicates which <a href="#callingconv">calling
1952 convention</a> the call should use. If none is specified, the call defaults
1953 to using C calling conventions.
1954 </li>
1955 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1956 function value being invoked. In most cases, this is a direct function
1957 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1958 an arbitrary pointer to function value.
1959 </li>
1960
1961 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1962 function to be invoked. </li>
1963
1964 <li>'<tt>function args</tt>': argument list whose types match the function
1965 signature argument types. If the function signature indicates the function
1966 accepts a variable number of arguments, the extra arguments can be
1967 specified. </li>
1968
1969 <li>'<tt>normal label</tt>': the label reached when the called function
1970 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1971
1972 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1973 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1974
1975</ol>
1976
1977<h5>Semantics:</h5>
1978
1979<p>This instruction is designed to operate as a standard '<tt><a
1980href="#i_call">call</a></tt>' instruction in most regards. The primary
1981difference is that it establishes an association with a label, which is used by
1982the runtime library to unwind the stack.</p>
1983
1984<p>This instruction is used in languages with destructors to ensure that proper
1985cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1986exception. Additionally, this is important for implementation of
1987'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1988
1989<h5>Example:</h5>
1990<pre>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]1991 %retval = invoke i32 @Test(i32 15) to label %Continue
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1992 unwind label %TestCleanup <i>; {i32}:retval set</i>
Nick Lewyckya1c11a12008-03-16 07:18:12 +0000[diff] [blame]1993 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Testfnptr(i32 15) to label %Continue
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1994 unwind label %TestCleanup <i>; {i32}:retval set</i>
1995</pre>
1996</div>
1997
1998
1999<!-- _______________________________________________________________________ -->
2000
2001<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
2002Instruction</a> </div>
2003
2004<div class="doc_text">
2005
2006<h5>Syntax:</h5>
2007<pre>
2008 unwind
2009</pre>
2010
2011<h5>Overview:</h5>
2012
2013<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
2014at the first callee in the dynamic call stack which used an <a
2015href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
2016primarily used to implement exception handling.</p>
2017
2018<h5>Semantics:</h5>
2019
2020<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
2021immediately halt. The dynamic call stack is then searched for the first <a
2022href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
2023execution continues at the "exceptional" destination block specified by the
2024<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
2025dynamic call chain, undefined behavior results.</p>
2026</div>
2027
2028<!-- _______________________________________________________________________ -->
2029
2030<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
2031Instruction</a> </div>
2032
2033<div class="doc_text">
2034
2035<h5>Syntax:</h5>
2036<pre>
2037 unreachable
2038</pre>
2039
2040<h5>Overview:</h5>
2041
2042<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
2043instruction is used to inform the optimizer that a particular portion of the
2044code is not reachable. This can be used to indicate that the code after a
2045no-return function cannot be reached, and other facts.</p>
2046
2047<h5>Semantics:</h5>
2048
2049<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
2050</div>
2051
2052
2053
2054<!-- ======================================================================= -->
2055<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
2056<div class="doc_text">
2057<p>Binary operators are used to do most of the computation in a
2058program. They require two operands, execute an operation on them, and
2059produce a single value. The operands might represent
2060multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
2061The result value of a binary operator is not
2062necessarily the same type as its operands.</p>
2063<p>There are several different binary operators:</p>
2064</div>
2065<!-- _______________________________________________________________________ -->
2066<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
2067Instruction</a> </div>
2068<div class="doc_text">
2069<h5>Syntax:</h5>
2070<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2071</pre>
2072<h5>Overview:</h5>
2073<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
2074<h5>Arguments:</h5>
2075<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
2076 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
2077 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2078Both arguments must have identical types.</p>
2079<h5>Semantics:</h5>
2080<p>The value produced is the integer or floating point sum of the two
2081operands.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2082<p>If an integer sum has unsigned overflow, the result returned is the
2083mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2084the result.</p>
2085<p>Because LLVM integers use a two's complement representation, this
2086instruction is appropriate for both signed and unsigned integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2087<h5>Example:</h5>
2088<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
2089</pre>
2090</div>
2091<!-- _______________________________________________________________________ -->
2092<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
2093Instruction</a> </div>
2094<div class="doc_text">
2095<h5>Syntax:</h5>
2096<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2097</pre>
2098<h5>Overview:</h5>
2099<p>The '<tt>sub</tt>' instruction returns the difference of its two
2100operands.</p>
2101<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
2102instruction present in most other intermediate representations.</p>
2103<h5>Arguments:</h5>
2104<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
2105 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2106values.
2107This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2108Both arguments must have identical types.</p>
2109<h5>Semantics:</h5>
2110<p>The value produced is the integer or floating point difference of
2111the two operands.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2112<p>If an integer difference has unsigned overflow, the result returned is the
2113mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2114the result.</p>
2115<p>Because LLVM integers use a two's complement representation, this
2116instruction is appropriate for both signed and unsigned integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2117<h5>Example:</h5>
2118<pre>
2119 &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2120 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2121</pre>
2122</div>
2123<!-- _______________________________________________________________________ -->
2124<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
2125Instruction</a> </div>
2126<div class="doc_text">
2127<h5>Syntax:</h5>
2128<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2129</pre>
2130<h5>Overview:</h5>
2131<p>The '<tt>mul</tt>' instruction returns the product of its two
2132operands.</p>
2133<h5>Arguments:</h5>
2134<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
2135 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
2136values.
2137This instruction can also take <a href="#t_vector">vector</a> versions of the values.
2138Both arguments must have identical types.</p>
2139<h5>Semantics:</h5>
2140<p>The value produced is the integer or floating point product of the
2141two operands.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2142<p>If the result of an integer multiplication has unsigned overflow,
2143the result returned is the mathematical result modulo
21442<sup>n</sup>, where n is the bit width of the result.</p>
2145<p>Because LLVM integers use a two's complement representation, and the
2146result is the same width as the operands, this instruction returns the
2147correct result for both signed and unsigned integers. If a full product
2148(e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands
2149should be sign-extended or zero-extended as appropriate to the
2150width of the full product.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2151<h5>Example:</h5>
2152<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2153</pre>
2154</div>
2155<!-- _______________________________________________________________________ -->
2156<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2157</a></div>
2158<div class="doc_text">
2159<h5>Syntax:</h5>
2160<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2161</pre>
2162<h5>Overview:</h5>
2163<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2164operands.</p>
2165<h5>Arguments:</h5>
2166<p>The two arguments to the '<tt>udiv</tt>' instruction must be
2167<a href="#t_integer">integer</a> values. Both arguments must have identical
2168types. This instruction can also take <a href="#t_vector">vector</a> versions
2169of the values in which case the elements must be integers.</p>
2170<h5>Semantics:</h5>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2171<p>The value produced is the unsigned integer quotient of the two operands.</p>
2172<p>Note that unsigned integer division and signed integer division are distinct
2173operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
2174<p>Division by zero leads to undefined behavior.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2175<h5>Example:</h5>
2176<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2177</pre>
2178</div>
2179<!-- _______________________________________________________________________ -->
2180<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2181</a> </div>
2182<div class="doc_text">
2183<h5>Syntax:</h5>
2184<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2185</pre>
2186<h5>Overview:</h5>
2187<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2188operands.</p>
2189<h5>Arguments:</h5>
2190<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2191<a href="#t_integer">integer</a> values. Both arguments must have identical
2192types. This instruction can also take <a href="#t_vector">vector</a> versions
2193of the values in which case the elements must be integers.</p>
2194<h5>Semantics:</h5>
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame^]2195<p>The value produced is the signed integer quotient of the two operands rounded towards zero.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2196<p>Note that signed integer division and unsigned integer division are distinct
2197operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
2198<p>Division by zero leads to undefined behavior. Overflow also leads to
2199undefined behavior; this is a rare case, but can occur, for example,
2200by doing a 32-bit division of -2147483648 by -1.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2201<h5>Example:</h5>
2202<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2203</pre>
2204</div>
2205<!-- _______________________________________________________________________ -->
2206<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2207Instruction</a> </div>
2208<div class="doc_text">
2209<h5>Syntax:</h5>
2210<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2211</pre>
2212<h5>Overview:</h5>
2213<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2214operands.</p>
2215<h5>Arguments:</h5>
2216<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2217<a href="#t_floating">floating point</a> values. Both arguments must have
2218identical types. This instruction can also take <a href="#t_vector">vector</a>
2219versions of floating point values.</p>
2220<h5>Semantics:</h5>
2221<p>The value produced is the floating point quotient of the two operands.</p>
2222<h5>Example:</h5>
2223<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2224</pre>
2225</div>
2226<!-- _______________________________________________________________________ -->
2227<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2228</div>
2229<div class="doc_text">
2230<h5>Syntax:</h5>
2231<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2232</pre>
2233<h5>Overview:</h5>
2234<p>The '<tt>urem</tt>' instruction returns the remainder from the
2235unsigned division of its two arguments.</p>
2236<h5>Arguments:</h5>
2237<p>The two arguments to the '<tt>urem</tt>' instruction must be
2238<a href="#t_integer">integer</a> values. Both arguments must have identical
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2239types. This instruction can also take <a href="#t_vector">vector</a> versions
2240of the values in which case the elements must be integers.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2241<h5>Semantics:</h5>
2242<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame^]2243This instruction always performs an unsigned division to get the remainder.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2244<p>Note that unsigned integer remainder and signed integer remainder are
2245distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
2246<p>Taking the remainder of a division by zero leads to undefined behavior.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2247<h5>Example:</h5>
2248<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2249</pre>
2250
2251</div>
2252<!-- _______________________________________________________________________ -->
2253<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
2254Instruction</a> </div>
2255<div class="doc_text">
2256<h5>Syntax:</h5>
2257<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2258</pre>
2259<h5>Overview:</h5>
2260<p>The '<tt>srem</tt>' instruction returns the remainder from the
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2261signed division of its two operands. This instruction can also take
2262<a href="#t_vector">vector</a> versions of the values in which case
2263the elements must be integers.</p>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]2264
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2265<h5>Arguments:</h5>
2266<p>The two arguments to the '<tt>srem</tt>' instruction must be
2267<a href="#t_integer">integer</a> values. Both arguments must have identical
2268types.</p>
2269<h5>Semantics:</h5>
2270<p>This instruction returns the <i>remainder</i> of a division (where the result
2271has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2272operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2273a value. For more information about the difference, see <a
2274 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2275Math Forum</a>. For a table of how this is implemented in various languages,
2276please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2277Wikipedia: modulo operation</a>.</p>
Chris Lattner9aba1e22008-01-28 00:36:27 +0000[diff] [blame]2278<p>Note that signed integer remainder and unsigned integer remainder are
2279distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
2280<p>Taking the remainder of a division by zero leads to undefined behavior.
2281Overflow also leads to undefined behavior; this is a rare case, but can occur,
2282for example, by taking the remainder of a 32-bit division of -2147483648 by -1.
2283(The remainder doesn't actually overflow, but this rule lets srem be
2284implemented using instructions that return both the result of the division
2285and the remainder.)</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2286<h5>Example:</h5>
2287<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2288</pre>
2289
2290</div>
2291<!-- _______________________________________________________________________ -->
2292<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2293Instruction</a> </div>
2294<div class="doc_text">
2295<h5>Syntax:</h5>
2296<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2297</pre>
2298<h5>Overview:</h5>
2299<p>The '<tt>frem</tt>' instruction returns the remainder from the
2300division of its two operands.</p>
2301<h5>Arguments:</h5>
2302<p>The two arguments to the '<tt>frem</tt>' instruction must be
2303<a href="#t_floating">floating point</a> values. Both arguments must have
Dan Gohman3e3fd8c2007-11-05 23:35:22 +0000[diff] [blame]2304identical types. This instruction can also take <a href="#t_vector">vector</a>
2305versions of floating point values.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2306<h5>Semantics:</h5>
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame^]2307<p>This instruction returns the <i>remainder</i> of a division.
2308The remainder has the same sign as the dividend.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2309<h5>Example:</h5>
2310<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2311</pre>
2312</div>
2313
2314<!-- ======================================================================= -->
2315<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2316Operations</a> </div>
2317<div class="doc_text">
2318<p>Bitwise binary operators are used to do various forms of
2319bit-twiddling in a program. They are generally very efficient
2320instructions and can commonly be strength reduced from other
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame^]2321instructions. They require two operands of the same type, execute an operation on them,
2322and produce a single value. The resulting value is the same type as its operands.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2323</div>
2324
2325<!-- _______________________________________________________________________ -->
2326<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2327Instruction</a> </div>
2328<div class="doc_text">
2329<h5>Syntax:</h5>
2330<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2331</pre>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2332
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2333<h5>Overview:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2334
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2335<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2336the left a specified number of bits.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2337
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2338<h5>Arguments:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2339
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2340<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2341 href="#t_integer">integer</a> type.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2342
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2343<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2344
Chris Lattnerdc15b1d2008-04-01 18:45:27 +0000[diff] [blame^]2345<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup> mod 2<sup>n</sup>,
2346where n is the width of the result. If <tt>var2</tt> is (statically or dynamically) negative or
2347equal to or larger than the number of bits in <tt>var1</tt>, the result is undefined.</p>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2348
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2349<h5>Example:</h5><pre>
2350 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2351 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2352 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2353 &lt;result&gt; = shl i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2354</pre>
2355</div>
2356<!-- _______________________________________________________________________ -->
2357<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2358Instruction</a> </div>
2359<div class="doc_text">
2360<h5>Syntax:</h5>
2361<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2362</pre>
2363
2364<h5>Overview:</h5>
2365<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2366operand shifted to the right a specified number of bits with zero fill.</p>
2367
2368<h5>Arguments:</h5>
2369<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2370<a href="#t_integer">integer</a> type.</p>
2371
2372<h5>Semantics:</h5>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2373
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2374<p>This instruction always performs a logical shift right operation. The most
2375significant bits of the result will be filled with zero bits after the
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2376shift. If <tt>var2</tt> is (statically or dynamically) equal to or larger than
2377the number of bits in <tt>var1</tt>, the result is undefined.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2378
2379<h5>Example:</h5>
2380<pre>
2381 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2382 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2383 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2384 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2385 &lt;result&gt; = lshr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2386</pre>
2387</div>
2388
2389<!-- _______________________________________________________________________ -->
2390<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2391Instruction</a> </div>
2392<div class="doc_text">
2393
2394<h5>Syntax:</h5>
2395<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2396</pre>
2397
2398<h5>Overview:</h5>
2399<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2400operand shifted to the right a specified number of bits with sign extension.</p>
2401
2402<h5>Arguments:</h5>
2403<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2404<a href="#t_integer">integer</a> type.</p>
2405
2406<h5>Semantics:</h5>
2407<p>This instruction always performs an arithmetic shift right operation,
2408The most significant bits of the result will be filled with the sign bit
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2409of <tt>var1</tt>. If <tt>var2</tt> is (statically or dynamically) equal to or
2410larger than the number of bits in <tt>var1</tt>, the result is undefined.
2411</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2412
2413<h5>Example:</h5>
2414<pre>
2415 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2416 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2417 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2418 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
Chris Lattnerd939d9f2007-10-03 21:01:14 +0000[diff] [blame]2419 &lt;result&gt; = ashr i32 1, 32 <i>; undefined</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2420</pre>
2421</div>
2422
2423<!-- _______________________________________________________________________ -->
2424<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2425Instruction</a> </div>
2426<div class="doc_text">
2427<h5>Syntax:</h5>
2428<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2429</pre>
2430<h5>Overview:</h5>
2431<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2432its two operands.</p>
2433<h5>Arguments:</h5>
2434<p>The two arguments to the '<tt>and</tt>' instruction must be <a
2435 href="#t_integer">integer</a> values. Both arguments must have
2436identical types.</p>
2437<h5>Semantics:</h5>
2438<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
2439<p> </p>
2440<div style="align: center">
2441<table border="1" cellspacing="0" cellpadding="4">
2442 <tbody>
2443 <tr>
2444 <td>In0</td>
2445 <td>In1</td>
2446 <td>Out</td>
2447 </tr>
2448 <tr>
2449 <td>0</td>
2450 <td>0</td>
2451 <td>0</td>
2452 </tr>
2453 <tr>
2454 <td>0</td>
2455 <td>1</td>
2456 <td>0</td>
2457 </tr>
2458 <tr>
2459 <td>1</td>
2460 <td>0</td>
2461 <td>0</td>
2462 </tr>
2463 <tr>
2464 <td>1</td>
2465 <td>1</td>
2466 <td>1</td>
2467 </tr>
2468 </tbody>
2469</table>
2470</div>
2471<h5>Example:</h5>
2472<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2473 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2474 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
2475</pre>
2476</div>
2477<!-- _______________________________________________________________________ -->
2478<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
2479<div class="doc_text">
2480<h5>Syntax:</h5>
2481<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2482</pre>
2483<h5>Overview:</h5>
2484<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2485or of its two operands.</p>
2486<h5>Arguments:</h5>
2487<p>The two arguments to the '<tt>or</tt>' instruction must be <a
2488 href="#t_integer">integer</a> values. Both arguments must have
2489identical types.</p>
2490<h5>Semantics:</h5>
2491<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
2492<p> </p>
2493<div style="align: center">
2494<table border="1" cellspacing="0" cellpadding="4">
2495 <tbody>
2496 <tr>
2497 <td>In0</td>
2498 <td>In1</td>
2499 <td>Out</td>
2500 </tr>
2501 <tr>
2502 <td>0</td>
2503 <td>0</td>
2504 <td>0</td>
2505 </tr>
2506 <tr>
2507 <td>0</td>
2508 <td>1</td>
2509 <td>1</td>
2510 </tr>
2511 <tr>
2512 <td>1</td>
2513 <td>0</td>
2514 <td>1</td>
2515 </tr>
2516 <tr>
2517 <td>1</td>
2518 <td>1</td>
2519 <td>1</td>
2520 </tr>
2521 </tbody>
2522</table>
2523</div>
2524<h5>Example:</h5>
2525<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2526 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2527 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
2528</pre>
2529</div>
2530<!-- _______________________________________________________________________ -->
2531<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2532Instruction</a> </div>
2533<div class="doc_text">
2534<h5>Syntax:</h5>
2535<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2536</pre>
2537<h5>Overview:</h5>
2538<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2539or of its two operands. The <tt>xor</tt> is used to implement the
2540"one's complement" operation, which is the "~" operator in C.</p>
2541<h5>Arguments:</h5>
2542<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
2543 href="#t_integer">integer</a> values. Both arguments must have
2544identical types.</p>
2545<h5>Semantics:</h5>
2546<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
2547<p> </p>
2548<div style="align: center">
2549<table border="1" cellspacing="0" cellpadding="4">
2550 <tbody>
2551 <tr>
2552 <td>In0</td>
2553 <td>In1</td>
2554 <td>Out</td>
2555 </tr>
2556 <tr>
2557 <td>0</td>
2558 <td>0</td>
2559 <td>0</td>
2560 </tr>
2561 <tr>
2562 <td>0</td>
2563 <td>1</td>
2564 <td>1</td>
2565 </tr>
2566 <tr>
2567 <td>1</td>
2568 <td>0</td>
2569 <td>1</td>
2570 </tr>
2571 <tr>
2572 <td>1</td>
2573 <td>1</td>
2574 <td>0</td>
2575 </tr>
2576 </tbody>
2577</table>
2578</div>
2579<p> </p>
2580<h5>Example:</h5>
2581<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2582 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2583 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2584 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
2585</pre>
2586</div>
2587
2588<!-- ======================================================================= -->
2589<div class="doc_subsection">
2590 <a name="vectorops">Vector Operations</a>
2591</div>
2592
2593<div class="doc_text">
2594
2595<p>LLVM supports several instructions to represent vector operations in a
2596target-independent manner. These instructions cover the element-access and
2597vector-specific operations needed to process vectors effectively. While LLVM
2598does directly support these vector operations, many sophisticated algorithms
2599will want to use target-specific intrinsics to take full advantage of a specific
2600target.</p>
2601
2602</div>
2603
2604<!-- _______________________________________________________________________ -->
2605<div class="doc_subsubsection">
2606 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2607</div>
2608
2609<div class="doc_text">
2610
2611<h5>Syntax:</h5>
2612
2613<pre>
2614 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2615</pre>
2616
2617<h5>Overview:</h5>
2618
2619<p>
2620The '<tt>extractelement</tt>' instruction extracts a single scalar
2621element from a vector at a specified index.
2622</p>
2623
2624
2625<h5>Arguments:</h5>
2626
2627<p>
2628The first operand of an '<tt>extractelement</tt>' instruction is a
2629value of <a href="#t_vector">vector</a> type. The second operand is
2630an index indicating the position from which to extract the element.
2631The index may be a variable.</p>
2632
2633<h5>Semantics:</h5>
2634
2635<p>
2636The result is a scalar of the same type as the element type of
2637<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2638<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2639results are undefined.
2640</p>
2641
2642<h5>Example:</h5>
2643
2644<pre>
2645 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
2646</pre>
2647</div>
2648
2649
2650<!-- _______________________________________________________________________ -->
2651<div class="doc_subsubsection">
2652 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2653</div>
2654
2655<div class="doc_text">
2656
2657<h5>Syntax:</h5>
2658
2659<pre>
2660 &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>
2661</pre>
2662
2663<h5>Overview:</h5>
2664
2665<p>
2666The '<tt>insertelement</tt>' instruction inserts a scalar
2667element into a vector at a specified index.
2668</p>
2669
2670
2671<h5>Arguments:</h5>
2672
2673<p>
2674The first operand of an '<tt>insertelement</tt>' instruction is a
2675value of <a href="#t_vector">vector</a> type. The second operand is a
2676scalar value whose type must equal the element type of the first
2677operand. The third operand is an index indicating the position at
2678which to insert the value. The index may be a variable.</p>
2679
2680<h5>Semantics:</h5>
2681
2682<p>
2683The result is a vector of the same type as <tt>val</tt>. Its
2684element values are those of <tt>val</tt> except at position
2685<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2686exceeds the length of <tt>val</tt>, the results are undefined.
2687</p>
2688
2689<h5>Example:</h5>
2690
2691<pre>
2692 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
2693</pre>
2694</div>
2695
2696<!-- _______________________________________________________________________ -->
2697<div class="doc_subsubsection">
2698 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2699</div>
2700
2701<div class="doc_text">
2702
2703<h5>Syntax:</h5>
2704
2705<pre>
2706 &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>
2707</pre>
2708
2709<h5>Overview:</h5>
2710
2711<p>
2712The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2713from two input vectors, returning a vector of the same type.
2714</p>
2715
2716<h5>Arguments:</h5>
2717
2718<p>
2719The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2720with types that match each other and types that match the result of the
2721instruction. The third argument is a shuffle mask, which has the same number
2722of elements as the other vector type, but whose element type is always 'i32'.
2723</p>
2724
2725<p>
2726The shuffle mask operand is required to be a constant vector with either
2727constant integer or undef values.
2728</p>
2729
2730<h5>Semantics:</h5>
2731
2732<p>
2733The elements of the two input vectors are numbered from left to right across
2734both of the vectors. The shuffle mask operand specifies, for each element of
2735the result vector, which element of the two input registers the result element
2736gets. The element selector may be undef (meaning "don't care") and the second
2737operand may be undef if performing a shuffle from only one vector.
2738</p>
2739
2740<h5>Example:</h5>
2741
2742<pre>
2743 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2744 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2745 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2746 &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.
2747</pre>
2748</div>
2749
2750
2751<!-- ======================================================================= -->
2752<div class="doc_subsection">
2753 <a name="memoryops">Memory Access and Addressing Operations</a>
2754</div>
2755
2756<div class="doc_text">
2757
2758<p>A key design point of an SSA-based representation is how it
2759represents memory. In LLVM, no memory locations are in SSA form, which
2760makes things very simple. This section describes how to read, write,
2761allocate, and free memory in LLVM.</p>
2762
2763</div>
2764
2765<!-- _______________________________________________________________________ -->
2766<div class="doc_subsubsection">
2767 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2768</div>
2769
2770<div class="doc_text">
2771
2772<h5>Syntax:</h5>
2773
2774<pre>
2775 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2776</pre>
2777
2778<h5>Overview:</h5>
2779
2780<p>The '<tt>malloc</tt>' instruction allocates memory from the system
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]2781heap and returns a pointer to it. The object is always allocated in the generic
2782address space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2783
2784<h5>Arguments:</h5>
2785
2786<p>The '<tt>malloc</tt>' instruction allocates
2787<tt>sizeof(&lt;type&gt;)*NumElements</tt>
2788bytes of memory from the operating system and returns a pointer of the
2789appropriate type to the program. If "NumElements" is specified, it is the
Gabor Greif5082cf42008-02-09 22:24:34 +0000[diff] [blame]2790number of elements allocated, otherwise "NumElements" is defaulted to be one.
2791If an alignment is specified, the value result of the allocation is guaranteed to
2792be aligned to at least that boundary. If not specified, or if zero, the target can
2793choose to align the allocation on any convenient boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2794
2795<p>'<tt>type</tt>' must be a sized type.</p>
2796
2797<h5>Semantics:</h5>
2798
2799<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2800a pointer is returned.</p>
2801
2802<h5>Example:</h5>
2803
2804<pre>
2805 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
2806
2807 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2808 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2809 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2810 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2811 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
2812</pre>
2813</div>
2814
2815<!-- _______________________________________________________________________ -->
2816<div class="doc_subsubsection">
2817 <a name="i_free">'<tt>free</tt>' Instruction</a>
2818</div>
2819
2820<div class="doc_text">
2821
2822<h5>Syntax:</h5>
2823
2824<pre>
2825 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
2826</pre>
2827
2828<h5>Overview:</h5>
2829
2830<p>The '<tt>free</tt>' instruction returns memory back to the unused
2831memory heap to be reallocated in the future.</p>
2832
2833<h5>Arguments:</h5>
2834
2835<p>'<tt>value</tt>' shall be a pointer value that points to a value
2836that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2837instruction.</p>
2838
2839<h5>Semantics:</h5>
2840
2841<p>Access to the memory pointed to by the pointer is no longer defined
2842after this instruction executes.</p>
2843
2844<h5>Example:</h5>
2845
2846<pre>
2847 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2848 free [4 x i8]* %array
2849</pre>
2850</div>
2851
2852<!-- _______________________________________________________________________ -->
2853<div class="doc_subsubsection">
2854 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2855</div>
2856
2857<div class="doc_text">
2858
2859<h5>Syntax:</h5>
2860
2861<pre>
2862 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
2863</pre>
2864
2865<h5>Overview:</h5>
2866
2867<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
2868currently executing function, to be automatically released when this function
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]2869returns to its caller. The object is always allocated in the generic address
2870space (address space zero).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2871
2872<h5>Arguments:</h5>
2873
2874<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
2875bytes of memory on the runtime stack, returning a pointer of the
Gabor Greif5082cf42008-02-09 22:24:34 +0000[diff] [blame]2876appropriate type to the program. If "NumElements" is specified, it is the
2877number of elements allocated, otherwise "NumElements" is defaulted to be one.
2878If an alignment is specified, the value result of the allocation is guaranteed
2879to be aligned to at least that boundary. If not specified, or if zero, the target
2880can choose to align the allocation on any convenient boundary.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2881
2882<p>'<tt>type</tt>' may be any sized type.</p>
2883
2884<h5>Semantics:</h5>
2885
2886<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
2887memory is automatically released when the function returns. The '<tt>alloca</tt>'
2888instruction is commonly used to represent automatic variables that must
2889have an address available. When the function returns (either with the <tt><a
2890 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
2891instructions), the memory is reclaimed.</p>
2892
2893<h5>Example:</h5>
2894
2895<pre>
2896 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2897 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2898 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2899 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
2900</pre>
2901</div>
2902
2903<!-- _______________________________________________________________________ -->
2904<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2905Instruction</a> </div>
2906<div class="doc_text">
2907<h5>Syntax:</h5>
2908<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>
2909<h5>Overview:</h5>
2910<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
2911<h5>Arguments:</h5>
2912<p>The argument to the '<tt>load</tt>' instruction specifies the memory
2913address from which to load. The pointer must point to a <a
2914 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
2915marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
2916the number or order of execution of this <tt>load</tt> with other
2917volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2918instructions. </p>
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2919<p>
2920The optional "align" argument specifies the alignment of the operation
2921(that is, the alignment of the memory address). A value of 0 or an
2922omitted "align" argument means that the operation has the preferential
2923alignment for the target. It is the responsibility of the code emitter
2924to ensure that the alignment information is correct. Overestimating
2925the alignment results in an undefined behavior. Underestimating the
2926alignment may produce less efficient code. An alignment of 1 is always
2927safe.
2928</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2929<h5>Semantics:</h5>
2930<p>The location of memory pointed to is loaded.</p>
2931<h5>Examples:</h5>
2932<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
2933 <a
2934 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2935 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
2936</pre>
2937</div>
2938<!-- _______________________________________________________________________ -->
2939<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2940Instruction</a> </div>
2941<div class="doc_text">
2942<h5>Syntax:</h5>
2943<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2944 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2945</pre>
2946<h5>Overview:</h5>
2947<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
2948<h5>Arguments:</h5>
2949<p>There are two arguments to the '<tt>store</tt>' instruction: a value
2950to store and an address at which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
2951operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
2952operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
2953optimizer is not allowed to modify the number or order of execution of
2954this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2955 href="#i_store">store</a></tt> instructions.</p>
Chris Lattner21003c82008-01-06 21:04:43 +0000[diff] [blame]2956<p>
2957The optional "align" argument specifies the alignment of the operation
2958(that is, the alignment of the memory address). A value of 0 or an
2959omitted "align" argument means that the operation has the preferential
2960alignment for the target. It is the responsibility of the code emitter
2961to ensure that the alignment information is correct. Overestimating
2962the alignment results in an undefined behavior. Underestimating the
2963alignment may produce less efficient code. An alignment of 1 is always
2964safe.
2965</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]2966<h5>Semantics:</h5>
2967<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2968at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
2969<h5>Example:</h5>
2970<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Bill Wendling63ffa142007-10-22 05:10:05 +0000[diff] [blame]2971 store i32 3, i32* %ptr <i>; yields {void}</i>
2972 %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]2973</pre>
2974</div>
2975
2976<!-- _______________________________________________________________________ -->
2977<div class="doc_subsubsection">
2978 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2979</div>
2980
2981<div class="doc_text">
2982<h5>Syntax:</h5>
2983<pre>
2984 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2985</pre>
2986
2987<h5>Overview:</h5>
2988
2989<p>
2990The '<tt>getelementptr</tt>' instruction is used to get the address of a
2991subelement of an aggregate data structure.</p>
2992
2993<h5>Arguments:</h5>
2994
2995<p>This instruction takes a list of integer operands that indicate what
2996elements of the aggregate object to index to. The actual types of the arguments
2997provided depend on the type of the first pointer argument. The
2998'<tt>getelementptr</tt>' instruction is used to index down through the type
2999levels of a structure or to a specific index in an array. When indexing into a
3000structure, only <tt>i32</tt> integer constants are allowed. When indexing
3001into an array or pointer, only integers of 32 or 64 bits are allowed, and will
3002be sign extended to 64-bit values.</p>
3003
3004<p>For example, let's consider a C code fragment and how it gets
3005compiled to LLVM:</p>
3006
3007<div class="doc_code">
3008<pre>
3009struct RT {
3010 char A;
3011 int B[10][20];
3012 char C;
3013};
3014struct ST {
3015 int X;
3016 double Y;
3017 struct RT Z;
3018};
3019
3020int *foo(struct ST *s) {
3021 return &amp;s[1].Z.B[5][13];
3022}
3023</pre>
3024</div>
3025
3026<p>The LLVM code generated by the GCC frontend is:</p>
3027
3028<div class="doc_code">
3029<pre>
3030%RT = type { i8 , [10 x [20 x i32]], i8 }
3031%ST = type { i32, double, %RT }
3032
3033define i32* %foo(%ST* %s) {
3034entry:
3035 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
3036 ret i32* %reg
3037}
3038</pre>
3039</div>
3040
3041<h5>Semantics:</h5>
3042
3043<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
3044on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
3045and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
3046<a href="#t_integer">integer</a> type but the value will always be sign extended
3047to 64-bits. <a href="#t_struct">Structure</a> types require <tt>i32</tt>
3048<b>constants</b>.</p>
3049
3050<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
3051type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
3052}</tt>' type, a structure. The second index indexes into the third element of
3053the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
3054i8 }</tt>' type, another structure. The third index indexes into the second
3055element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
3056array. The two dimensions of the array are subscripted into, yielding an
3057'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
3058to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
3059
3060<p>Note that it is perfectly legal to index partially through a
3061structure, returning a pointer to an inner element. Because of this,
3062the LLVM code for the given testcase is equivalent to:</p>
3063
3064<pre>
3065 define i32* %foo(%ST* %s) {
3066 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
3067 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
3068 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
3069 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
3070 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
3071 ret i32* %t5
3072 }
3073</pre>
3074
3075<p>Note that it is undefined to access an array out of bounds: array and
3076pointer indexes must always be within the defined bounds of the array type.
3077The one exception for this rules is zero length arrays. These arrays are
3078defined to be accessible as variable length arrays, which requires access
3079beyond the zero'th element.</p>
3080
3081<p>The getelementptr instruction is often confusing. For some more insight
3082into how it works, see <a href="GetElementPtr.html">the getelementptr
3083FAQ</a>.</p>
3084
3085<h5>Example:</h5>
3086
3087<pre>
3088 <i>; yields [12 x i8]*:aptr</i>
3089 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
3090</pre>
3091</div>
3092
3093<!-- ======================================================================= -->
3094<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
3095</div>
3096<div class="doc_text">
3097<p>The instructions in this category are the conversion instructions (casting)
3098which all take a single operand and a type. They perform various bit conversions
3099on the operand.</p>
3100</div>
3101
3102<!-- _______________________________________________________________________ -->
3103<div class="doc_subsubsection">
3104 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
3105</div>
3106<div class="doc_text">
3107
3108<h5>Syntax:</h5>
3109<pre>
3110 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3111</pre>
3112
3113<h5>Overview:</h5>
3114<p>
3115The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
3116</p>
3117
3118<h5>Arguments:</h5>
3119<p>
3120The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
3121be an <a href="#t_integer">integer</a> type, and a type that specifies the size
3122and type of the result, which must be an <a href="#t_integer">integer</a>
3123type. The bit size of <tt>value</tt> must be larger than the bit size of
3124<tt>ty2</tt>. Equal sized types are not allowed.</p>
3125
3126<h5>Semantics:</h5>
3127<p>
3128The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
3129and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
3130larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
3131It will always truncate bits.</p>
3132
3133<h5>Example:</h5>
3134<pre>
3135 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
3136 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
3137 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
3138</pre>
3139</div>
3140
3141<!-- _______________________________________________________________________ -->
3142<div class="doc_subsubsection">
3143 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3144</div>
3145<div class="doc_text">
3146
3147<h5>Syntax:</h5>
3148<pre>
3149 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3150</pre>
3151
3152<h5>Overview:</h5>
3153<p>The '<tt>zext</tt>' instruction zero extends its operand to type
3154<tt>ty2</tt>.</p>
3155
3156
3157<h5>Arguments:</h5>
3158<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3159<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3160also be of <a href="#t_integer">integer</a> type. The bit size of the
3161<tt>value</tt> must be smaller than the bit size of the destination type,
3162<tt>ty2</tt>.</p>
3163
3164<h5>Semantics:</h5>
3165<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3166bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3167
3168<p>When zero extending from i1, the result will always be either 0 or 1.</p>
3169
3170<h5>Example:</h5>
3171<pre>
3172 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3173 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3174</pre>
3175</div>
3176
3177<!-- _______________________________________________________________________ -->
3178<div class="doc_subsubsection">
3179 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3180</div>
3181<div class="doc_text">
3182
3183<h5>Syntax:</h5>
3184<pre>
3185 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3186</pre>
3187
3188<h5>Overview:</h5>
3189<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3190
3191<h5>Arguments:</h5>
3192<p>
3193The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3194<a href="#t_integer">integer</a> type, and a type to cast it to, which must
3195also be of <a href="#t_integer">integer</a> type. The bit size of the
3196<tt>value</tt> must be smaller than the bit size of the destination type,
3197<tt>ty2</tt>.</p>
3198
3199<h5>Semantics:</h5>
3200<p>
3201The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3202bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3203the type <tt>ty2</tt>.</p>
3204
3205<p>When sign extending from i1, the extension always results in -1 or 0.</p>
3206
3207<h5>Example:</h5>
3208<pre>
3209 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3210 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3211</pre>
3212</div>
3213
3214<!-- _______________________________________________________________________ -->
3215<div class="doc_subsubsection">
3216 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3217</div>
3218
3219<div class="doc_text">
3220
3221<h5>Syntax:</h5>
3222
3223<pre>
3224 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3225</pre>
3226
3227<h5>Overview:</h5>
3228<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
3229<tt>ty2</tt>.</p>
3230
3231
3232<h5>Arguments:</h5>
3233<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
3234 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
3235cast it to. The size of <tt>value</tt> must be larger than the size of
3236<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
3237<i>no-op cast</i>.</p>
3238
3239<h5>Semantics:</h5>
3240<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
3241<a href="#t_floating">floating point</a> type to a smaller
3242<a href="#t_floating">floating point</a> type. If the value cannot fit within
3243the destination type, <tt>ty2</tt>, then the results are undefined.</p>
3244
3245<h5>Example:</h5>
3246<pre>
3247 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
3248 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
3249</pre>
3250</div>
3251
3252<!-- _______________________________________________________________________ -->
3253<div class="doc_subsubsection">
3254 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
3255</div>
3256<div class="doc_text">
3257
3258<h5>Syntax:</h5>
3259<pre>
3260 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3261</pre>
3262
3263<h5>Overview:</h5>
3264<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
3265floating point value.</p>
3266
3267<h5>Arguments:</h5>
3268<p>The '<tt>fpext</tt>' instruction takes a
3269<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
3270and a <a href="#t_floating">floating point</a> type to cast it to. The source
3271type must be smaller than the destination type.</p>
3272
3273<h5>Semantics:</h5>
3274<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
3275<a href="#t_floating">floating point</a> type to a larger
3276<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
3277used to make a <i>no-op cast</i> because it always changes bits. Use
3278<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
3279
3280<h5>Example:</h5>
3281<pre>
3282 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
3283 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
3284</pre>
3285</div>
3286
3287<!-- _______________________________________________________________________ -->
3288<div class="doc_subsubsection">
3289 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
3290</div>
3291<div class="doc_text">
3292
3293<h5>Syntax:</h5>
3294<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3295 &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]3296</pre>
3297
3298<h5>Overview:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3299<p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3300unsigned integer equivalent of type <tt>ty2</tt>.
3301</p>
3302
3303<h5>Arguments:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3304<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]3305scalar or vector <a href="#t_floating">floating point</a> value, and a type
3306to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3307type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3308vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3309
3310<h5>Semantics:</h5>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3311<p> The '<tt>fptoui</tt>' instruction converts its
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3312<a href="#t_floating">floating point</a> operand into the nearest (rounding
3313towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3314the results are undefined.</p>
3315
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3316<h5>Example:</h5>
3317<pre>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3318 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3319 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
Reid Spencere6adee82007-07-31 14:40:14 +0000[diff] [blame]3320 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3321</pre>
3322</div>
3323
3324<!-- _______________________________________________________________________ -->
3325<div class="doc_subsubsection">
3326 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
3327</div>
3328<div class="doc_text">
3329
3330<h5>Syntax:</h5>
3331<pre>
3332 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3333</pre>
3334
3335<h5>Overview:</h5>
3336<p>The '<tt>fptosi</tt>' instruction converts
3337<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
3338</p>
3339
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3340<h5>Arguments:</h5>
3341<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]3342scalar or vector <a href="#t_floating">floating point</a> value, and a type
3343to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3344type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3345vector integer type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3346
3347<h5>Semantics:</h5>
3348<p>The '<tt>fptosi</tt>' instruction converts its
3349<a href="#t_floating">floating point</a> operand into the nearest (rounding
3350towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3351the results are undefined.</p>
3352
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3353<h5>Example:</h5>
3354<pre>
3355 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
Chris Lattner681f1e82007-09-22 03:17:52 +0000[diff] [blame]3356 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3357 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
3358</pre>
3359</div>
3360
3361<!-- _______________________________________________________________________ -->
3362<div class="doc_subsubsection">
3363 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
3364</div>
3365<div class="doc_text">
3366
3367<h5>Syntax:</h5>
3368<pre>
3369 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3370</pre>
3371
3372<h5>Overview:</h5>
3373<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
3374integer and converts that value to the <tt>ty2</tt> type.</p>
3375
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3376<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3377<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
3378scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3379to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3380type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3381floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3382
3383<h5>Semantics:</h5>
3384<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
3385integer quantity and converts it to the corresponding floating point value. If
3386the value cannot fit in the floating point value, the results are undefined.</p>
3387
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3388<h5>Example:</h5>
3389<pre>
3390 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3391 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
3392</pre>
3393</div>
3394
3395<!-- _______________________________________________________________________ -->
3396<div class="doc_subsubsection">
3397 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
3398</div>
3399<div class="doc_text">
3400
3401<h5>Syntax:</h5>
3402<pre>
3403 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3404</pre>
3405
3406<h5>Overview:</h5>
3407<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
3408integer and converts that value to the <tt>ty2</tt> type.</p>
3409
3410<h5>Arguments:</h5>
Nate Begeman78246ca2007-11-17 03:58:34 +0000[diff] [blame]3411<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
3412scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3413to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3414type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3415floating point type with the same number of elements as <tt>ty</tt></p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3416
3417<h5>Semantics:</h5>
3418<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
3419integer quantity and converts it to the corresponding floating point value. If
3420the value cannot fit in the floating point value, the results are undefined.</p>
3421
3422<h5>Example:</h5>
3423<pre>
3424 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3425 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
3426</pre>
3427</div>
3428
3429<!-- _______________________________________________________________________ -->
3430<div class="doc_subsubsection">
3431 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3432</div>
3433<div class="doc_text">
3434
3435<h5>Syntax:</h5>
3436<pre>
3437 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3438</pre>
3439
3440<h5>Overview:</h5>
3441<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3442the integer type <tt>ty2</tt>.</p>
3443
3444<h5>Arguments:</h5>
3445<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3446must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
3447<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3448
3449<h5>Semantics:</h5>
3450<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3451<tt>ty2</tt> by interpreting the pointer value as an integer and either
3452truncating or zero extending that value to the size of the integer type. If
3453<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3454<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3455are the same size, then nothing is done (<i>no-op cast</i>) other than a type
3456change.</p>
3457
3458<h5>Example:</h5>
3459<pre>
3460 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
3461 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
3462</pre>
3463</div>
3464
3465<!-- _______________________________________________________________________ -->
3466<div class="doc_subsubsection">
3467 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3468</div>
3469<div class="doc_text">
3470
3471<h5>Syntax:</h5>
3472<pre>
3473 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3474</pre>
3475
3476<h5>Overview:</h5>
3477<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3478a pointer type, <tt>ty2</tt>.</p>
3479
3480<h5>Arguments:</h5>
3481<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
3482value to cast, and a type to cast it to, which must be a
3483<a href="#t_pointer">pointer</a> type.
3484
3485<h5>Semantics:</h5>
3486<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3487<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3488the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3489size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3490the size of a pointer then a zero extension is done. If they are the same size,
3491nothing is done (<i>no-op cast</i>).</p>
3492
3493<h5>Example:</h5>
3494<pre>
3495 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
3496 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
3497 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
3498</pre>
3499</div>
3500
3501<!-- _______________________________________________________________________ -->
3502<div class="doc_subsubsection">
3503 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
3504</div>
3505<div class="doc_text">
3506
3507<h5>Syntax:</h5>
3508<pre>
3509 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3510</pre>
3511
3512<h5>Overview:</h5>
3513<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3514<tt>ty2</tt> without changing any bits.</p>
3515
3516<h5>Arguments:</h5>
3517<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
3518a first class value, and a type to cast it to, which must also be a <a
3519 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
3520and the destination type, <tt>ty2</tt>, must be identical. If the source
3521type is a pointer, the destination type must also be a pointer.</p>
3522
3523<h5>Semantics:</h5>
3524<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3525<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3526this conversion. The conversion is done as if the <tt>value</tt> had been
3527stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3528converted to other pointer types with this instruction. To convert pointers to
3529other types, use the <a href="#i_inttoptr">inttoptr</a> or
3530<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
3531
3532<h5>Example:</h5>
3533<pre>
3534 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3535 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3536 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
3537</pre>
3538</div>
3539
3540<!-- ======================================================================= -->
3541<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3542<div class="doc_text">
3543<p>The instructions in this category are the "miscellaneous"
3544instructions, which defy better classification.</p>
3545</div>
3546
3547<!-- _______________________________________________________________________ -->
3548<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3549</div>
3550<div class="doc_text">
3551<h5>Syntax:</h5>
3552<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3553</pre>
3554<h5>Overview:</h5>
3555<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3556of its two integer operands.</p>
3557<h5>Arguments:</h5>
3558<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3559the condition code indicating the kind of comparison to perform. It is not
3560a value, just a keyword. The possible condition code are:
3561<ol>
3562 <li><tt>eq</tt>: equal</li>
3563 <li><tt>ne</tt>: not equal </li>
3564 <li><tt>ugt</tt>: unsigned greater than</li>
3565 <li><tt>uge</tt>: unsigned greater or equal</li>
3566 <li><tt>ult</tt>: unsigned less than</li>
3567 <li><tt>ule</tt>: unsigned less or equal</li>
3568 <li><tt>sgt</tt>: signed greater than</li>
3569 <li><tt>sge</tt>: signed greater or equal</li>
3570 <li><tt>slt</tt>: signed less than</li>
3571 <li><tt>sle</tt>: signed less or equal</li>
3572</ol>
3573<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
3574<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
3575<h5>Semantics:</h5>
3576<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3577the condition code given as <tt>cond</tt>. The comparison performed always
3578yields a <a href="#t_primitive">i1</a> result, as follows:
3579<ol>
3580 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3581 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3582 </li>
3583 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3584 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3585 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3586 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3587 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3588 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3589 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3590 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3591 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3592 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3593 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3594 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3595 <li><tt>sge</tt>: interprets the operands as signed values and yields
3596 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3597 <li><tt>slt</tt>: interprets the operands as signed values and yields
3598 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3599 <li><tt>sle</tt>: interprets the operands as signed values and yields
3600 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3601</ol>
3602<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3603values are compared as if they were integers.</p>
3604
3605<h5>Example:</h5>
3606<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3607 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3608 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3609 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3610 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3611 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
3612</pre>
3613</div>
3614
3615<!-- _______________________________________________________________________ -->
3616<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3617</div>
3618<div class="doc_text">
3619<h5>Syntax:</h5>
3620<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {i1}:result</i>
3621</pre>
3622<h5>Overview:</h5>
3623<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3624of its floating point operands.</p>
3625<h5>Arguments:</h5>
3626<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3627the condition code indicating the kind of comparison to perform. It is not
3628a value, just a keyword. The possible condition code are:
3629<ol>
3630 <li><tt>false</tt>: no comparison, always returns false</li>
3631 <li><tt>oeq</tt>: ordered and equal</li>
3632 <li><tt>ogt</tt>: ordered and greater than </li>
3633 <li><tt>oge</tt>: ordered and greater than or equal</li>
3634 <li><tt>olt</tt>: ordered and less than </li>
3635 <li><tt>ole</tt>: ordered and less than or equal</li>
3636 <li><tt>one</tt>: ordered and not equal</li>
3637 <li><tt>ord</tt>: ordered (no nans)</li>
3638 <li><tt>ueq</tt>: unordered or equal</li>
3639 <li><tt>ugt</tt>: unordered or greater than </li>
3640 <li><tt>uge</tt>: unordered or greater than or equal</li>
3641 <li><tt>ult</tt>: unordered or less than </li>
3642 <li><tt>ule</tt>: unordered or less than or equal</li>
3643 <li><tt>une</tt>: unordered or not equal</li>
3644 <li><tt>uno</tt>: unordered (either nans)</li>
3645 <li><tt>true</tt>: no comparison, always returns true</li>
3646</ol>
3647<p><i>Ordered</i> means that neither operand is a QNAN while
3648<i>unordered</i> means that either operand may be a QNAN.</p>
3649<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3650<a href="#t_floating">floating point</a> typed. They must have identical
3651types.</p>
3652<h5>Semantics:</h5>
3653<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3654the condition code given as <tt>cond</tt>. The comparison performed always
3655yields a <a href="#t_primitive">i1</a> result, as follows:
3656<ol>
3657 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
3658 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3659 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3660 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3661 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
3662 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3663 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3664 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3665 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3666 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3667 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3668 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3669 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3670 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3671 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
3672 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
3673 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
3674 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3675 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
3676 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3677 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
3678 <tt>var1</tt> is less than <tt>var2</tt>.</li>
3679 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
3680 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3681 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
3682 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
3683 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
3684 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3685</ol>
3686
3687<h5>Example:</h5>
3688<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3689 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3690 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3691 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3692</pre>
3693</div>
3694
3695<!-- _______________________________________________________________________ -->
3696<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3697Instruction</a> </div>
3698<div class="doc_text">
3699<h5>Syntax:</h5>
3700<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3701<h5>Overview:</h5>
3702<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3703the SSA graph representing the function.</p>
3704<h5>Arguments:</h5>
3705<p>The type of the incoming values is specified with the first type
3706field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3707as arguments, with one pair for each predecessor basic block of the
3708current block. Only values of <a href="#t_firstclass">first class</a>
3709type may be used as the value arguments to the PHI node. Only labels
3710may be used as the label arguments.</p>
3711<p>There must be no non-phi instructions between the start of a basic
3712block and the PHI instructions: i.e. PHI instructions must be first in
3713a basic block.</p>
3714<h5>Semantics:</h5>
3715<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
3716specified by the pair corresponding to the predecessor basic block that executed
3717just prior to the current block.</p>
3718<h5>Example:</h5>
3719<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>
3720</div>
3721
3722<!-- _______________________________________________________________________ -->
3723<div class="doc_subsubsection">
3724 <a name="i_select">'<tt>select</tt>' Instruction</a>
3725</div>
3726
3727<div class="doc_text">
3728
3729<h5>Syntax:</h5>
3730
3731<pre>
3732 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
3733</pre>
3734
3735<h5>Overview:</h5>
3736
3737<p>
3738The '<tt>select</tt>' instruction is used to choose one value based on a
3739condition, without branching.
3740</p>
3741
3742
3743<h5>Arguments:</h5>
3744
3745<p>
3746The '<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.
3747</p>
3748
3749<h5>Semantics:</h5>
3750
3751<p>
3752If the boolean condition evaluates to true, the instruction returns the first
3753value argument; otherwise, it returns the second value argument.
3754</p>
3755
3756<h5>Example:</h5>
3757
3758<pre>
3759 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
3760</pre>
3761</div>
3762
3763
3764<!-- _______________________________________________________________________ -->
3765<div class="doc_subsubsection">
3766 <a name="i_call">'<tt>call</tt>' Instruction</a>
3767</div>
3768
3769<div class="doc_text">
3770
3771<h5>Syntax:</h5>
3772<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3773 &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]3774</pre>
3775
3776<h5>Overview:</h5>
3777
3778<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
3779
3780<h5>Arguments:</h5>
3781
3782<p>This instruction requires several arguments:</p>
3783
3784<ol>
3785 <li>
3786 <p>The optional "tail" marker indicates whether the callee function accesses
3787 any allocas or varargs in the caller. If the "tail" marker is present, the
3788 function call is eligible for tail call optimization. Note that calls may
3789 be marked "tail" even if they do not occur before a <a
3790 href="#i_ret"><tt>ret</tt></a> instruction.
3791 </li>
3792 <li>
3793 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
3794 convention</a> the call should use. If none is specified, the call defaults
3795 to using C calling conventions.
3796 </li>
3797 <li>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3798 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
3799 the type of the return value. Functions that return no value are marked
3800 <tt><a href="#t_void">void</a></tt>.</p>
3801 </li>
3802 <li>
3803 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
3804 value being invoked. The argument types must match the types implied by
3805 this signature. This type can be omitted if the function is not varargs
3806 and if the function type does not return a pointer to a function.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3807 </li>
3808 <li>
3809 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3810 be invoked. In most cases, this is a direct function invocation, but
3811 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
3812 to function value.</p>
3813 </li>
3814 <li>
3815 <p>'<tt>function args</tt>': argument list whose types match the
3816 function signature argument types. All arguments must be of
3817 <a href="#t_firstclass">first class</a> type. If the function signature
3818 indicates the function accepts a variable number of arguments, the extra
3819 arguments can be specified.</p>
3820 </li>
3821</ol>
3822
3823<h5>Semantics:</h5>
3824
3825<p>The '<tt>call</tt>' instruction is used to cause control flow to
3826transfer to a specified function, with its incoming arguments bound to
3827the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3828instruction in the called function, control flow continues with the
3829instruction after the function call, and the return value of the
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]3830function is bound to the result argument. If the callee returns multiple
3831values then the return values of the function are only accessible through
3832the '<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3833
3834<h5>Example:</h5>
3835
3836<pre>
Nick Lewycky93082fc2007-09-08 13:57:50 +0000[diff] [blame]3837 %retval = call i32 @test(i32 %argc)
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]3838 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42) <i>; yields i32</i>
3839 %X = tail call i32 @foo() <i>; yields i32</i>
3840 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
3841 call void %foo(i8 97 signext)
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3842
3843 %struct.A = type { i32, i8 }
Chris Lattner5e893ef2008-03-21 17:24:17 +0000[diff] [blame]3844 %r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
3845 %gr = getresult %struct.A %r, 0 <i>; yields i32</i>
3846 %gr1 = getresult %struct.A %r, 1 <i>; yields i8</i>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3847</pre>
3848
3849</div>
3850
3851<!-- _______________________________________________________________________ -->
3852<div class="doc_subsubsection">
3853 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
3854</div>
3855
3856<div class="doc_text">
3857
3858<h5>Syntax:</h5>
3859
3860<pre>
3861 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
3862</pre>
3863
3864<h5>Overview:</h5>
3865
3866<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
3867the "variable argument" area of a function call. It is used to implement the
3868<tt>va_arg</tt> macro in C.</p>
3869
3870<h5>Arguments:</h5>
3871
3872<p>This instruction takes a <tt>va_list*</tt> value and the type of
3873the argument. It returns a value of the specified argument type and
3874increments the <tt>va_list</tt> to point to the next argument. The
3875actual type of <tt>va_list</tt> is target specific.</p>
3876
3877<h5>Semantics:</h5>
3878
3879<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3880type from the specified <tt>va_list</tt> and causes the
3881<tt>va_list</tt> to point to the next argument. For more information,
3882see the variable argument handling <a href="#int_varargs">Intrinsic
3883Functions</a>.</p>
3884
3885<p>It is legal for this instruction to be called in a function which does not
3886take a variable number of arguments, for example, the <tt>vfprintf</tt>
3887function.</p>
3888
3889<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
3890href="#intrinsics">intrinsic function</a> because it takes a type as an
3891argument.</p>
3892
3893<h5>Example:</h5>
3894
3895<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3896
3897</div>
3898
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3899<!-- _______________________________________________________________________ -->
3900<div class="doc_subsubsection">
3901 <a name="i_getresult">'<tt>getresult</tt>' Instruction</a>
3902</div>
3903
3904<div class="doc_text">
3905
3906<h5>Syntax:</h5>
3907<pre>
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3908 &lt;resultval&gt; = getresult &lt;type&gt; &lt;retval&gt;, &lt;index&gt;
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3909</pre>
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3910
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3911<h5>Overview:</h5>
3912
3913<p> The '<tt>getresult</tt>' instruction is used to extract individual values
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3914from a '<tt><a href="#i_call">call</a></tt>'
3915or '<tt><a href="#i_invoke">invoke</a></tt>' instruction that returns multiple
3916results.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3917
3918<h5>Arguments:</h5>
3919
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3920<p>The '<tt>getresult</tt>' instruction takes a call or invoke value as its
3921first argument. The value must have <a href="#t_struct">structure type</a>.
3922The second argument is an unsigned index value which must be in range for
3923the number of values returned by the call.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3924
3925<h5>Semantics:</h5>
3926
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3927<p>The '<tt>getresult</tt>' instruction extracts the element identified by
3928'<tt>index</tt>' from the aggregate value.</p>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3929
3930<h5>Example:</h5>
3931
3932<pre>
3933 %struct.A = type { i32, i8 }
3934
3935 %r = call %struct.A @foo()
Chris Lattneree9da3f2008-03-21 17:20:51 +0000[diff] [blame]3936 %gr = getresult %struct.A %r, 0 <i>; yields i32:%gr</i>
3937 %gr1 = getresult %struct.A %r, 1 <i>; yields i8:%gr1</i>
Devang Patela3cc5372008-03-10 20:49:15 +0000[diff] [blame]3938 add i32 %gr, 42
3939 add i8 %gr1, 41
3940</pre>
3941
3942</div>
3943
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3944<!-- *********************************************************************** -->
3945<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3946<!-- *********************************************************************** -->
3947
3948<div class="doc_text">
3949
3950<p>LLVM supports the notion of an "intrinsic function". These functions have
3951well known names and semantics and are required to follow certain restrictions.
3952Overall, these intrinsics represent an extension mechanism for the LLVM
3953language that does not require changing all of the transformations in LLVM when
3954adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
3955
3956<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3957prefix is reserved in LLVM for intrinsic names; thus, function names may not
3958begin with this prefix. Intrinsic functions must always be external functions:
3959you cannot define the body of intrinsic functions. Intrinsic functions may
3960only be used in call or invoke instructions: it is illegal to take the address
3961of an intrinsic function. Additionally, because intrinsic functions are part
3962of the LLVM language, it is required if any are added that they be documented
3963here.</p>
3964
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3965<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
3966a family of functions that perform the same operation but on different data
3967types. Because LLVM can represent over 8 million different integer types,
3968overloading is used commonly to allow an intrinsic function to operate on any
3969integer type. One or more of the argument types or the result type can be
3970overloaded to accept any integer type. Argument types may also be defined as
3971exactly matching a previous argument's type or the result type. This allows an
3972intrinsic function which accepts multiple arguments, but needs all of them to
3973be of the same type, to only be overloaded with respect to a single argument or
3974the result.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3975
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]3976<p>Overloaded intrinsics will have the names of its overloaded argument types
3977encoded into its function name, each preceded by a period. Only those types
3978which are overloaded result in a name suffix. Arguments whose type is matched
3979against another type do not. For example, the <tt>llvm.ctpop</tt> function can
3980take an integer of any width and returns an integer of exactly the same integer
3981width. This leads to a family of functions such as
3982<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
3983Only one type, the return type, is overloaded, and only one type suffix is
3984required. Because the argument's type is matched against the return type, it
3985does not require its own name suffix.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]3986
3987<p>To learn how to add an intrinsic function, please see the
3988<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
3989</p>
3990
3991</div>
3992
3993<!-- ======================================================================= -->
3994<div class="doc_subsection">
3995 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3996</div>
3997
3998<div class="doc_text">
3999
4000<p>Variable argument support is defined in LLVM with the <a
4001 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
4002intrinsic functions. These functions are related to the similarly
4003named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
4004
4005<p>All of these functions operate on arguments that use a
4006target-specific value type "<tt>va_list</tt>". The LLVM assembly
4007language reference manual does not define what this type is, so all
4008transformations should be prepared to handle these functions regardless of
4009the type used.</p>
4010
4011<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
4012instruction and the variable argument handling intrinsic functions are
4013used.</p>
4014
4015<div class="doc_code">
4016<pre>
4017define i32 @test(i32 %X, ...) {
4018 ; Initialize variable argument processing
4019 %ap = alloca i8*
4020 %ap2 = bitcast i8** %ap to i8*
4021 call void @llvm.va_start(i8* %ap2)
4022
4023 ; Read a single integer argument
4024 %tmp = va_arg i8** %ap, i32
4025
4026 ; Demonstrate usage of llvm.va_copy and llvm.va_end
4027 %aq = alloca i8*
4028 %aq2 = bitcast i8** %aq to i8*
4029 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
4030 call void @llvm.va_end(i8* %aq2)
4031
4032 ; Stop processing of arguments.
4033 call void @llvm.va_end(i8* %ap2)
4034 ret i32 %tmp
4035}
4036
4037declare void @llvm.va_start(i8*)
4038declare void @llvm.va_copy(i8*, i8*)
4039declare void @llvm.va_end(i8*)
4040</pre>
4041</div>
4042
4043</div>
4044
4045<!-- _______________________________________________________________________ -->
4046<div class="doc_subsubsection">
4047 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
4048</div>
4049
4050
4051<div class="doc_text">
4052<h5>Syntax:</h5>
4053<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
4054<h5>Overview:</h5>
4055<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
4056<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
4057href="#i_va_arg">va_arg</a></tt>.</p>
4058
4059<h5>Arguments:</h5>
4060
4061<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
4062
4063<h5>Semantics:</h5>
4064
4065<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
4066macro available in C. In a target-dependent way, it initializes the
4067<tt>va_list</tt> element to which the argument points, so that the next call to
4068<tt>va_arg</tt> will produce the first variable argument passed to the function.
4069Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
4070last argument of the function as the compiler can figure that out.</p>
4071
4072</div>
4073
4074<!-- _______________________________________________________________________ -->
4075<div class="doc_subsubsection">
4076 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
4077</div>
4078
4079<div class="doc_text">
4080<h5>Syntax:</h5>
4081<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
4082<h5>Overview:</h5>
4083
4084<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
4085which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
4086or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
4087
4088<h5>Arguments:</h5>
4089
4090<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
4091
4092<h5>Semantics:</h5>
4093
4094<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
4095macro available in C. In a target-dependent way, it destroys the
4096<tt>va_list</tt> element to which the argument points. Calls to <a
4097href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
4098<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
4099<tt>llvm.va_end</tt>.</p>
4100
4101</div>
4102
4103<!-- _______________________________________________________________________ -->
4104<div class="doc_subsubsection">
4105 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
4106</div>
4107
4108<div class="doc_text">
4109
4110<h5>Syntax:</h5>
4111
4112<pre>
4113 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
4114</pre>
4115
4116<h5>Overview:</h5>
4117
4118<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
4119from the source argument list to the destination argument list.</p>
4120
4121<h5>Arguments:</h5>
4122
4123<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
4124The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
4125
4126
4127<h5>Semantics:</h5>
4128
4129<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
4130macro available in C. In a target-dependent way, it copies the source
4131<tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
4132intrinsic is necessary because the <tt><a href="#int_va_start">
4133llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
4134example, memory allocation.</p>
4135
4136</div>
4137
4138<!-- ======================================================================= -->
4139<div class="doc_subsection">
4140 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
4141</div>
4142
4143<div class="doc_text">
4144
4145<p>
4146LLVM support for <a href="GarbageCollection.html">Accurate Garbage
4147Collection</a> requires the implementation and generation of these intrinsics.
4148These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
4149stack</a>, as well as garbage collector implementations that require <a
4150href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
4151Front-ends for type-safe garbage collected languages should generate these
4152intrinsics to make use of the LLVM garbage collectors. For more details, see <a
4153href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
4154</p>
Christopher Lambcfe00962007-12-17 01:00:21 +0000[diff] [blame]4155
4156<p>The garbage collection intrinsics only operate on objects in the generic
4157 address space (address space zero).</p>
4158
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4159</div>
4160
4161<!-- _______________________________________________________________________ -->
4162<div class="doc_subsubsection">
4163 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
4164</div>
4165
4166<div class="doc_text">
4167
4168<h5>Syntax:</h5>
4169
4170<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4171 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4172</pre>
4173
4174<h5>Overview:</h5>
4175
4176<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
4177the code generator, and allows some metadata to be associated with it.</p>
4178
4179<h5>Arguments:</h5>
4180
4181<p>The first argument specifies the address of a stack object that contains the
4182root pointer. The second pointer (which must be either a constant or a global
4183value address) contains the meta-data to be associated with the root.</p>
4184
4185<h5>Semantics:</h5>
4186
4187<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
4188location. At compile-time, the code generator generates information to allow
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4189the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
4190intrinsic may only be used in a function which <a href="#gc">specifies a GC
4191algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4192
4193</div>
4194
4195
4196<!-- _______________________________________________________________________ -->
4197<div class="doc_subsubsection">
4198 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
4199</div>
4200
4201<div class="doc_text">
4202
4203<h5>Syntax:</h5>
4204
4205<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4206 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4207</pre>
4208
4209<h5>Overview:</h5>
4210
4211<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
4212locations, allowing garbage collector implementations that require read
4213barriers.</p>
4214
4215<h5>Arguments:</h5>
4216
4217<p>The second argument is the address to read from, which should be an address
4218allocated from the garbage collector. The first object is a pointer to the
4219start of the referenced object, if needed by the language runtime (otherwise
4220null).</p>
4221
4222<h5>Semantics:</h5>
4223
4224<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
4225instruction, but may be replaced with substantially more complex code by the
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4226garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
4227may only be used in a function which <a href="#gc">specifies a GC
4228algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4229
4230</div>
4231
4232
4233<!-- _______________________________________________________________________ -->
4234<div class="doc_subsubsection">
4235 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
4236</div>
4237
4238<div class="doc_text">
4239
4240<h5>Syntax:</h5>
4241
4242<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4243 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4244</pre>
4245
4246<h5>Overview:</h5>
4247
4248<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
4249locations, allowing garbage collector implementations that require write
4250barriers (such as generational or reference counting collectors).</p>
4251
4252<h5>Arguments:</h5>
4253
4254<p>The first argument is the reference to store, the second is the start of the
4255object to store it to, and the third is the address of the field of Obj to
4256store to. If the runtime does not require a pointer to the object, Obj may be
4257null.</p>
4258
4259<h5>Semantics:</h5>
4260
4261<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
4262instruction, but may be replaced with substantially more complex code by the
Gordon Henriksen40393542007-12-25 02:31:26 +0000[diff] [blame]4263garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
4264may only be used in a function which <a href="#gc">specifies a GC
4265algorithm</a>.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4266
4267</div>
4268
4269
4270
4271<!-- ======================================================================= -->
4272<div class="doc_subsection">
4273 <a name="int_codegen">Code Generator Intrinsics</a>
4274</div>
4275
4276<div class="doc_text">
4277<p>
4278These intrinsics are provided by LLVM to expose special features that may only
4279be implemented with code generator support.
4280</p>
4281
4282</div>
4283
4284<!-- _______________________________________________________________________ -->
4285<div class="doc_subsubsection">
4286 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
4287</div>
4288
4289<div class="doc_text">
4290
4291<h5>Syntax:</h5>
4292<pre>
4293 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
4294</pre>
4295
4296<h5>Overview:</h5>
4297
4298<p>
4299The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
4300target-specific value indicating the return address of the current function
4301or one of its callers.
4302</p>
4303
4304<h5>Arguments:</h5>
4305
4306<p>
4307The argument to this intrinsic indicates which function to return the address
4308for. Zero indicates the calling function, one indicates its caller, etc. The
4309argument is <b>required</b> to be a constant integer value.
4310</p>
4311
4312<h5>Semantics:</h5>
4313
4314<p>
4315The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
4316the return address of the specified call frame, or zero if it cannot be
4317identified. The value returned by this intrinsic is likely to be incorrect or 0
4318for arguments other than zero, so it should only be used for debugging purposes.
4319</p>
4320
4321<p>
4322Note that calling this intrinsic does not prevent function inlining or other
4323aggressive transformations, so the value returned may not be that of the obvious
4324source-language caller.
4325</p>
4326</div>
4327
4328
4329<!-- _______________________________________________________________________ -->
4330<div class="doc_subsubsection">
4331 <a name="int_frameaddress">'<tt>llvm.frameaddress</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 i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4339</pre>
4340
4341<h5>Overview:</h5>
4342
4343<p>
4344The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
4345target-specific frame pointer value for the specified stack frame.
4346</p>
4347
4348<h5>Arguments:</h5>
4349
4350<p>
4351The argument to this intrinsic indicates which function to return the frame
4352pointer for. Zero indicates the calling function, one indicates its caller,
4353etc. The argument is <b>required</b> to be a constant integer value.
4354</p>
4355
4356<h5>Semantics:</h5>
4357
4358<p>
4359The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
4360the frame address of the specified call frame, or zero if it cannot be
4361identified. The value returned by this intrinsic is likely to be incorrect or 0
4362for arguments other than zero, so it should only be used for debugging purposes.
4363</p>
4364
4365<p>
4366Note that calling this intrinsic does not prevent function inlining or other
4367aggressive transformations, so the value returned may not be that of the obvious
4368source-language caller.
4369</p>
4370</div>
4371
4372<!-- _______________________________________________________________________ -->
4373<div class="doc_subsubsection">
4374 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
4375</div>
4376
4377<div class="doc_text">
4378
4379<h5>Syntax:</h5>
4380<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4381 declare i8 *@llvm.stacksave()
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4382</pre>
4383
4384<h5>Overview:</h5>
4385
4386<p>
4387The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
4388the function stack, for use with <a href="#int_stackrestore">
4389<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4390features like scoped automatic variable sized arrays in C99.
4391</p>
4392
4393<h5>Semantics:</h5>
4394
4395<p>
4396This intrinsic returns a opaque pointer value that can be passed to <a
4397href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
4398<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4399<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4400state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4401practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4402that were allocated after the <tt>llvm.stacksave</tt> was executed.
4403</p>
4404
4405</div>
4406
4407<!-- _______________________________________________________________________ -->
4408<div class="doc_subsubsection">
4409 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
4410</div>
4411
4412<div class="doc_text">
4413
4414<h5>Syntax:</h5>
4415<pre>
4416 declare void @llvm.stackrestore(i8 * %ptr)
4417</pre>
4418
4419<h5>Overview:</h5>
4420
4421<p>
4422The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4423the function stack to the state it was in when the corresponding <a
4424href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
4425useful for implementing language features like scoped automatic variable sized
4426arrays in C99.
4427</p>
4428
4429<h5>Semantics:</h5>
4430
4431<p>
4432See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
4433</p>
4434
4435</div>
4436
4437
4438<!-- _______________________________________________________________________ -->
4439<div class="doc_subsubsection">
4440 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
4441</div>
4442
4443<div class="doc_text">
4444
4445<h5>Syntax:</h5>
4446<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4447 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]4448</pre>
4449
4450<h5>Overview:</h5>
4451
4452
4453<p>
4454The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
4455a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4456no
4457effect on the behavior of the program but can change its performance
4458characteristics.
4459</p>
4460
4461<h5>Arguments:</h5>
4462
4463<p>
4464<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4465determining if the fetch should be for a read (0) or write (1), and
4466<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
4467locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
4468<tt>locality</tt> arguments must be constant integers.
4469</p>
4470
4471<h5>Semantics:</h5>
4472
4473<p>
4474This intrinsic does not modify the behavior of the program. In particular,
4475prefetches cannot trap and do not produce a value. On targets that support this
4476intrinsic, the prefetch can provide hints to the processor cache for better
4477performance.
4478</p>
4479
4480</div>
4481
4482<!-- _______________________________________________________________________ -->
4483<div class="doc_subsubsection">
4484 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4485</div>
4486
4487<div class="doc_text">
4488
4489<h5>Syntax:</h5>
4490<pre>
Chris Lattner38bd5dd2007-09-21 17:30:40 +0000[diff] [blame]4491 declare void @llvm.pcmarker(i32 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4492</pre>
4493
4494<h5>Overview:</h5>
4495
4496
4497<p>
4498The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4499(PC) in a region of
4500code to simulators and other tools. The method is target specific, but it is
4501expected that the marker will use exported symbols to transmit the PC of the marker.
4502The marker makes no guarantees that it will remain with any specific instruction
4503after optimizations. It is possible that the presence of a marker will inhibit
4504optimizations. The intended use is to be inserted after optimizations to allow
4505correlations of simulation runs.
4506</p>
4507
4508<h5>Arguments:</h5>
4509
4510<p>
4511<tt>id</tt> is a numerical id identifying the marker.
4512</p>
4513
4514<h5>Semantics:</h5>
4515
4516<p>
4517This intrinsic does not modify the behavior of the program. Backends that do not
4518support this intrinisic may ignore it.
4519</p>
4520
4521</div>
4522
4523<!-- _______________________________________________________________________ -->
4524<div class="doc_subsubsection">
4525 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4526</div>
4527
4528<div class="doc_text">
4529
4530<h5>Syntax:</h5>
4531<pre>
4532 declare i64 @llvm.readcyclecounter( )
4533</pre>
4534
4535<h5>Overview:</h5>
4536
4537
4538<p>
4539The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4540counter register (or similar low latency, high accuracy clocks) on those targets
4541that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4542As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4543should only be used for small timings.
4544</p>
4545
4546<h5>Semantics:</h5>
4547
4548<p>
4549When directly supported, reading the cycle counter should not modify any memory.
4550Implementations are allowed to either return a application specific value or a
4551system wide value. On backends without support, this is lowered to a constant 0.
4552</p>
4553
4554</div>
4555
4556<!-- ======================================================================= -->
4557<div class="doc_subsection">
4558 <a name="int_libc">Standard C Library Intrinsics</a>
4559</div>
4560
4561<div class="doc_text">
4562<p>
4563LLVM provides intrinsics for a few important standard C library functions.
4564These intrinsics allow source-language front-ends to pass information about the
4565alignment of the pointer arguments to the code generator, providing opportunity
4566for more efficient code generation.
4567</p>
4568
4569</div>
4570
4571<!-- _______________________________________________________________________ -->
4572<div class="doc_subsubsection">
4573 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4574</div>
4575
4576<div class="doc_text">
4577
4578<h5>Syntax:</h5>
4579<pre>
4580 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4581 i32 &lt;len&gt;, i32 &lt;align&gt;)
4582 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4583 i64 &lt;len&gt;, i32 &lt;align&gt;)
4584</pre>
4585
4586<h5>Overview:</h5>
4587
4588<p>
4589The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4590location to the destination location.
4591</p>
4592
4593<p>
4594Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4595intrinsics do 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, the second is a pointer to
4602the source. The third argument is an integer argument
4603specifying the number of bytes to copy, and the fourth argument is the alignment
4604of the source and destination locations.
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 both the source and destination pointers are aligned
4610to that boundary.
4611</p>
4612
4613<h5>Semantics:</h5>
4614
4615<p>
4616The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
4617location to the destination location, which are not allowed to overlap. It
4618copies "len" bytes of memory over. If the argument is known to be aligned to
4619some boundary, this can be specified as the fourth argument, otherwise it should
4620be set to 0 or 1.
4621</p>
4622</div>
4623
4624
4625<!-- _______________________________________________________________________ -->
4626<div class="doc_subsubsection">
4627 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4628</div>
4629
4630<div class="doc_text">
4631
4632<h5>Syntax:</h5>
4633<pre>
4634 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4635 i32 &lt;len&gt;, i32 &lt;align&gt;)
4636 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4637 i64 &lt;len&gt;, i32 &lt;align&gt;)
4638</pre>
4639
4640<h5>Overview:</h5>
4641
4642<p>
4643The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4644location to the destination location. It is similar to the
Chris Lattnerdba16ea2008-01-06 19:51:52 +0000[diff] [blame]4645'<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to overlap.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4646</p>
4647
4648<p>
4649Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4650intrinsics do not return a value, and takes an extra alignment argument.
4651</p>
4652
4653<h5>Arguments:</h5>
4654
4655<p>
4656The first argument is a pointer to the destination, the second is a pointer to
4657the source. The third argument is an integer argument
4658specifying the number of bytes to copy, and the fourth argument is the alignment
4659of the source and destination locations.
4660</p>
4661
4662<p>
4663If the call to this intrinisic has an alignment value that is not 0 or 1, then
4664the caller guarantees that the source and destination pointers are aligned to
4665that boundary.
4666</p>
4667
4668<h5>Semantics:</h5>
4669
4670<p>
4671The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
4672location to the destination location, which may overlap. It
4673copies "len" bytes of memory over. If the argument is known to be aligned to
4674some boundary, this can be specified as the fourth argument, otherwise it should
4675be set to 0 or 1.
4676</p>
4677</div>
4678
4679
4680<!-- _______________________________________________________________________ -->
4681<div class="doc_subsubsection">
4682 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
4683</div>
4684
4685<div class="doc_text">
4686
4687<h5>Syntax:</h5>
4688<pre>
4689 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4690 i32 &lt;len&gt;, i32 &lt;align&gt;)
4691 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4692 i64 &lt;len&gt;, i32 &lt;align&gt;)
4693</pre>
4694
4695<h5>Overview:</h5>
4696
4697<p>
4698The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
4699byte value.
4700</p>
4701
4702<p>
4703Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4704does not return a value, and takes an extra alignment argument.
4705</p>
4706
4707<h5>Arguments:</h5>
4708
4709<p>
4710The first argument is a pointer to the destination to fill, the second is the
4711byte value to fill it with, the third argument is an integer
4712argument specifying the number of bytes to fill, and the fourth argument is the
4713known alignment of destination location.
4714</p>
4715
4716<p>
4717If the call to this intrinisic has an alignment value that is not 0 or 1, then
4718the caller guarantees that the destination pointer is aligned to that boundary.
4719</p>
4720
4721<h5>Semantics:</h5>
4722
4723<p>
4724The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4725the
4726destination location. If the argument is known to be aligned to some boundary,
4727this can be specified as the fourth argument, otherwise it should be set to 0 or
47281.
4729</p>
4730</div>
4731
4732
4733<!-- _______________________________________________________________________ -->
4734<div class="doc_subsubsection">
4735 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
4736</div>
4737
4738<div class="doc_text">
4739
4740<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4741<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]4742floating point or vector of floating point type. Not all targets support all
4743types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4744<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4745 declare float @llvm.sqrt.f32(float %Val)
4746 declare double @llvm.sqrt.f64(double %Val)
4747 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
4748 declare fp128 @llvm.sqrt.f128(fp128 %Val)
4749 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4750</pre>
4751
4752<h5>Overview:</h5>
4753
4754<p>
4755The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4756returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4757<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
Chris Lattnerf914a002008-01-29 07:00:44 +0000[diff] [blame]4758negative numbers other than -0.0 (which allows for better optimization, because
4759there is no need to worry about errno being set). <tt>llvm.sqrt(-0.0)</tt> is
4760defined to return -0.0 like IEEE sqrt.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4761</p>
4762
4763<h5>Arguments:</h5>
4764
4765<p>
4766The argument and return value are floating point numbers of the same type.
4767</p>
4768
4769<h5>Semantics:</h5>
4770
4771<p>
4772This function returns the sqrt of the specified operand if it is a nonnegative
4773floating point number.
4774</p>
4775</div>
4776
4777<!-- _______________________________________________________________________ -->
4778<div class="doc_subsubsection">
4779 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4780</div>
4781
4782<div class="doc_text">
4783
4784<h5>Syntax:</h5>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4785<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]4786floating point or vector of floating point type. Not all targets support all
4787types however.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4788<pre>
Dale Johannesenf9adbb62007-10-02 17:47:38 +0000[diff] [blame]4789 declare float @llvm.powi.f32(float %Val, i32 %power)
4790 declare double @llvm.powi.f64(double %Val, i32 %power)
4791 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
4792 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
4793 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4794</pre>
4795
4796<h5>Overview:</h5>
4797
4798<p>
4799The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4800specified (positive or negative) power. The order of evaluation of
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4801multiplications is not defined. When a vector of floating point type is
4802used, the second argument remains a scalar integer value.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4803</p>
4804
4805<h5>Arguments:</h5>
4806
4807<p>
4808The second argument is an integer power, and the first is a value to raise to
4809that power.
4810</p>
4811
4812<h5>Semantics:</h5>
4813
4814<p>
4815This function returns the first value raised to the second power with an
4816unspecified sequence of rounding operations.</p>
4817</div>
4818
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4819<!-- _______________________________________________________________________ -->
4820<div class="doc_subsubsection">
4821 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
4822</div>
4823
4824<div class="doc_text">
4825
4826<h5>Syntax:</h5>
4827<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
4828floating point or vector of floating point type. Not all targets support all
4829types however.
4830<pre>
4831 declare float @llvm.sin.f32(float %Val)
4832 declare double @llvm.sin.f64(double %Val)
4833 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
4834 declare fp128 @llvm.sin.f128(fp128 %Val)
4835 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
4836</pre>
4837
4838<h5>Overview:</h5>
4839
4840<p>
4841The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
4842</p>
4843
4844<h5>Arguments:</h5>
4845
4846<p>
4847The argument and return value are floating point numbers of the same type.
4848</p>
4849
4850<h5>Semantics:</h5>
4851
4852<p>
4853This function returns the sine of the specified operand, returning the
4854same values as the libm <tt>sin</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4855conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4856</div>
4857
4858<!-- _______________________________________________________________________ -->
4859<div class="doc_subsubsection">
4860 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
4861</div>
4862
4863<div class="doc_text">
4864
4865<h5>Syntax:</h5>
4866<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
4867floating point or vector of floating point type. Not all targets support all
4868types however.
4869<pre>
4870 declare float @llvm.cos.f32(float %Val)
4871 declare double @llvm.cos.f64(double %Val)
4872 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
4873 declare fp128 @llvm.cos.f128(fp128 %Val)
4874 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
4875</pre>
4876
4877<h5>Overview:</h5>
4878
4879<p>
4880The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
4881</p>
4882
4883<h5>Arguments:</h5>
4884
4885<p>
4886The argument and return value are floating point numbers of the same type.
4887</p>
4888
4889<h5>Semantics:</h5>
4890
4891<p>
4892This function returns the cosine of the specified operand, returning the
4893same values as the libm <tt>cos</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4894conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4895</div>
4896
4897<!-- _______________________________________________________________________ -->
4898<div class="doc_subsubsection">
4899 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
4900</div>
4901
4902<div class="doc_text">
4903
4904<h5>Syntax:</h5>
4905<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
4906floating point or vector of floating point type. Not all targets support all
4907types however.
4908<pre>
4909 declare float @llvm.pow.f32(float %Val, float %Power)
4910 declare double @llvm.pow.f64(double %Val, double %Power)
4911 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
4912 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
4913 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
4914</pre>
4915
4916<h5>Overview:</h5>
4917
4918<p>
4919The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
4920specified (positive or negative) power.
4921</p>
4922
4923<h5>Arguments:</h5>
4924
4925<p>
4926The second argument is a floating point power, and the first is a value to
4927raise to that power.
4928</p>
4929
4930<h5>Semantics:</h5>
4931
4932<p>
4933This function returns the first value raised to the second power,
4934returning the
4935same values as the libm <tt>pow</tt> functions would, and handles error
Dan Gohmaneaba92e2007-10-17 18:05:13 +0000[diff] [blame]4936conditions in the same way.</p>
Dan Gohman361079c2007-10-15 20:30:11 +0000[diff] [blame]4937</div>
4938
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4939
4940<!-- ======================================================================= -->
4941<div class="doc_subsection">
4942 <a name="int_manip">Bit Manipulation Intrinsics</a>
4943</div>
4944
4945<div class="doc_text">
4946<p>
4947LLVM provides intrinsics for a few important bit manipulation operations.
4948These allow efficient code generation for some algorithms.
4949</p>
4950
4951</div>
4952
4953<!-- _______________________________________________________________________ -->
4954<div class="doc_subsubsection">
4955 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4956</div>
4957
4958<div class="doc_text">
4959
4960<h5>Syntax:</h5>
4961<p>This is an overloaded intrinsic function. You can use bswap on any integer
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4962type that is an even number of bytes (i.e. BitWidth % 16 == 0).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4963<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4964 declare i16 @llvm.bswap.i16(i16 &lt;id&gt;)
4965 declare i32 @llvm.bswap.i32(i32 &lt;id&gt;)
4966 declare i64 @llvm.bswap.i64(i64 &lt;id&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4967</pre>
4968
4969<h5>Overview:</h5>
4970
4971<p>
4972The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
4973values with an even number of bytes (positive multiple of 16 bits). These are
4974useful for performing operations on data that is not in the target's native
4975byte order.
4976</p>
4977
4978<h5>Semantics:</h5>
4979
4980<p>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]4981The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4982and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4983intrinsic returns an i32 value that has the four bytes of the input i32
4984swapped, 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]4985i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
4986<tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]4987additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
4988</p>
4989
4990</div>
4991
4992<!-- _______________________________________________________________________ -->
4993<div class="doc_subsubsection">
4994 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
4995</div>
4996
4997<div class="doc_text">
4998
4999<h5>Syntax:</h5>
5000<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
5001width. Not all targets support all bit widths however.
5002<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5003 declare i8 @llvm.ctpop.i8 (i8 &lt;src&gt;)
5004 declare i16 @llvm.ctpop.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5005 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5006 declare i64 @llvm.ctpop.i64(i64 &lt;src&gt;)
5007 declare i256 @llvm.ctpop.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5008</pre>
5009
5010<h5>Overview:</h5>
5011
5012<p>
5013The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
5014value.
5015</p>
5016
5017<h5>Arguments:</h5>
5018
5019<p>
5020The only argument is the value to be counted. The argument may be of any
5021integer type. The return type must match the argument type.
5022</p>
5023
5024<h5>Semantics:</h5>
5025
5026<p>
5027The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
5028</p>
5029</div>
5030
5031<!-- _______________________________________________________________________ -->
5032<div class="doc_subsubsection">
5033 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
5034</div>
5035
5036<div class="doc_text">
5037
5038<h5>Syntax:</h5>
5039<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
5040integer bit width. Not all targets support all bit widths however.
5041<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5042 declare i8 @llvm.ctlz.i8 (i8 &lt;src&gt;)
5043 declare i16 @llvm.ctlz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5044 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5045 declare i64 @llvm.ctlz.i64(i64 &lt;src&gt;)
5046 declare i256 @llvm.ctlz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5047</pre>
5048
5049<h5>Overview:</h5>
5050
5051<p>
5052The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
5053leading zeros in a variable.
5054</p>
5055
5056<h5>Arguments:</h5>
5057
5058<p>
5059The only argument is the value to be counted. The argument may be of any
5060integer type. The return type must match the argument type.
5061</p>
5062
5063<h5>Semantics:</h5>
5064
5065<p>
5066The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
5067in a variable. If the src == 0 then the result is the size in bits of the type
5068of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
5069</p>
5070</div>
5071
5072
5073
5074<!-- _______________________________________________________________________ -->
5075<div class="doc_subsubsection">
5076 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
5077</div>
5078
5079<div class="doc_text">
5080
5081<h5>Syntax:</h5>
5082<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
5083integer bit width. Not all targets support all bit widths however.
5084<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5085 declare i8 @llvm.cttz.i8 (i8 &lt;src&gt;)
5086 declare i16 @llvm.cttz.i16(i16 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5087 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5088 declare i64 @llvm.cttz.i64(i64 &lt;src&gt;)
5089 declare i256 @llvm.cttz.i256(i256 &lt;src&gt;)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5090</pre>
5091
5092<h5>Overview:</h5>
5093
5094<p>
5095The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
5096trailing zeros.
5097</p>
5098
5099<h5>Arguments:</h5>
5100
5101<p>
5102The only argument is the value to be counted. The argument may be of any
5103integer type. The return type must match the argument type.
5104</p>
5105
5106<h5>Semantics:</h5>
5107
5108<p>
5109The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
5110in a variable. If the src == 0 then the result is the size in bits of the type
5111of src. For example, <tt>llvm.cttz(2) = 1</tt>.
5112</p>
5113</div>
5114
5115<!-- _______________________________________________________________________ -->
5116<div class="doc_subsubsection">
5117 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
5118</div>
5119
5120<div class="doc_text">
5121
5122<h5>Syntax:</h5>
5123<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
5124on any integer bit width.
5125<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5126 declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
5127 declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5128</pre>
5129
5130<h5>Overview:</h5>
5131<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
5132range of bits from an integer value and returns them in the same bit width as
5133the original value.</p>
5134
5135<h5>Arguments:</h5>
5136<p>The first argument, <tt>%val</tt> and the result may be integer types of
5137any bit width but they must have the same bit width. The second and third
5138arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
5139
5140<h5>Semantics:</h5>
5141<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
5142of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
5143<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
5144operates in forward mode.</p>
5145<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
5146right by <tt>%loBit</tt> bits and then ANDing it with a mask with
5147only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
5148<ol>
5149 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
5150 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
5151 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
5152 to determine the number of bits to retain.</li>
5153 <li>A mask of the retained bits is created by shifting a -1 value.</li>
5154 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
5155</ol>
5156<p>In reverse mode, a similar computation is made except that the bits are
5157returned in the reverse order. So, for example, if <tt>X</tt> has the value
5158<tt>i16 0x0ACF (101011001111)</tt> and we apply
5159<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
5160<tt>i16 0x0026 (000000100110)</tt>.</p>
5161</div>
5162
5163<div class="doc_subsubsection">
5164 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
5165</div>
5166
5167<div class="doc_text">
5168
5169<h5>Syntax:</h5>
5170<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
5171on any integer bit width.
5172<pre>
Chandler Carrutha228e392007-08-04 01:51:18 +0000[diff] [blame]5173 declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
5174 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]5175</pre>
5176
5177<h5>Overview:</h5>
5178<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
5179of bits in an integer value with another integer value. It returns the integer
5180with the replaced bits.</p>
5181
5182<h5>Arguments:</h5>
5183<p>The first argument, <tt>%val</tt> and the result may be integer types of
5184any bit width but they must have the same bit width. <tt>%val</tt> is the value
5185whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
5186integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
5187type since they specify only a bit index.</p>
5188
5189<h5>Semantics:</h5>
5190<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
5191of operation: forwards and reverse. If <tt>%lo</tt> is greater than
5192<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
5193operates in forward mode.</p>
5194<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
5195truncating it down to the size of the replacement area or zero extending it
5196up to that size.</p>
5197<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
5198are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
5199in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
5200to the <tt>%hi</tt>th bit.
5201<p>In reverse mode, a similar computation is made except that the bits are
5202reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
5203<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
5204<h5>Examples:</h5>
5205<pre>
5206 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
5207 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0xFF0F
5208 llvm.part.set(0xFFFF, 1, 7, 4) -&gt; 0xFF8F
5209 llvm.part.set(0xFFFF, F, 8, 3) -&gt; 0xFFE7
5210 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
5211</pre>
5212</div>
5213
5214<!-- ======================================================================= -->
5215<div class="doc_subsection">
5216 <a name="int_debugger">Debugger Intrinsics</a>
5217</div>
5218
5219<div class="doc_text">
5220<p>
5221The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
5222are described in the <a
5223href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
5224Debugging</a> document.
5225</p>
5226</div>
5227
5228
5229<!-- ======================================================================= -->
5230<div class="doc_subsection">
5231 <a name="int_eh">Exception Handling Intrinsics</a>
5232</div>
5233
5234<div class="doc_text">
5235<p> The LLVM exception handling intrinsics (which all start with
5236<tt>llvm.eh.</tt> prefix), are described in the <a
5237href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
5238Handling</a> document. </p>
5239</div>
5240
5241<!-- ======================================================================= -->
5242<div class="doc_subsection">
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5243 <a name="int_trampoline">Trampoline Intrinsic</a>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5244</div>
5245
5246<div class="doc_text">
5247<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5248 This intrinsic makes it possible to excise one parameter, marked with
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5249 the <tt>nest</tt> attribute, from a function. The result is a callable
5250 function pointer lacking the nest parameter - the caller does not need
5251 to provide a value for it. Instead, the value to use is stored in
5252 advance in a "trampoline", a block of memory usually allocated
5253 on the stack, which also contains code to splice the nest value into the
5254 argument list. This is used to implement the GCC nested function address
5255 extension.
5256</p>
5257<p>
5258 For example, if the function is
5259 <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]5260 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]5261<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5262 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
5263 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
5264 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
5265 %fp = bitcast i8* %p to i32 (i32, i32)*
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5266</pre>
Bill Wendlinge262b4c2007-09-22 09:23:55 +0000[diff] [blame]5267 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
5268 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5269</div>
5270
5271<!-- _______________________________________________________________________ -->
5272<div class="doc_subsubsection">
5273 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
5274</div>
5275<div class="doc_text">
5276<h5>Syntax:</h5>
5277<pre>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5278declare 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]5279</pre>
5280<h5>Overview:</h5>
5281<p>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5282 This fills the memory pointed to by <tt>tramp</tt> with code
5283 and returns a function pointer suitable for executing it.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5284</p>
5285<h5>Arguments:</h5>
5286<p>
5287 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
5288 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
5289 and sufficiently aligned block of memory; this memory is written to by the
Duncan Sands35012212007-08-22 23:39:54 +0000[diff] [blame]5290 intrinsic. Note that the size and the alignment are target-specific - LLVM
5291 currently provides no portable way of determining them, so a front-end that
5292 generates this intrinsic needs to have some target-specific knowledge.
5293 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]5294</p>
5295<h5>Semantics:</h5>
5296<p>
5297 The block of memory pointed to by <tt>tramp</tt> is filled with target
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5298 dependent code, turning it into a function. A pointer to this function is
5299 returned, but needs to be bitcast to an
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5300 <a href="#int_trampoline">appropriate function pointer type</a>
Duncan Sands7407a9f2007-09-11 14:10:23 +0000[diff] [blame]5301 before being called. The new function's signature is the same as that of
5302 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
5303 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
5304 of pointer type. Calling the new function is equivalent to calling
5305 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
5306 missing <tt>nest</tt> argument. If, after calling
5307 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
5308 modified, then the effect of any later call to the returned function pointer is
5309 undefined.
Duncan Sands38947cd2007-07-27 12:58:54 +0000[diff] [blame]5310</p>
5311</div>
5312
5313<!-- ======================================================================= -->
5314<div class="doc_subsection">
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]5315 <a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
5316</div>
5317
5318<div class="doc_text">
5319<p>
5320 These intrinsic functions expand the "universal IR" of LLVM to represent
5321 hardware constructs for atomic operations and memory synchronization. This
5322 provides an interface to the hardware, not an interface to the programmer. It
5323 is aimed at a low enough level to allow any programming models or APIs which
5324 need atomic behaviors to map cleanly onto it. It is also modeled primarily on
5325 hardware behavior. Just as hardware provides a "universal IR" for source
5326 languages, it also provides a starting point for developing a "universal"
5327 atomic operation and synchronization IR.
5328</p>
5329<p>
5330 These do <em>not</em> form an API such as high-level threading libraries,
5331 software transaction memory systems, atomic primitives, and intrinsic
5332 functions as found in BSD, GNU libc, atomic_ops, APR, and other system and
5333 application libraries. The hardware interface provided by LLVM should allow
5334 a clean implementation of all of these APIs and parallel programming models.
5335 No one model or paradigm should be selected above others unless the hardware
5336 itself ubiquitously does so.
5337
5338</p>
5339</div>
5340
5341<!-- _______________________________________________________________________ -->
5342<div class="doc_subsubsection">
5343 <a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
5344</div>
5345<div class="doc_text">
5346<h5>Syntax:</h5>
5347<pre>
5348declare void @llvm.memory.barrier( i1 &lt;ll&gt;, i1 &lt;ls&gt;, i1 &lt;sl&gt;, i1 &lt;ss&gt;,
5349i1 &lt;device&gt; )
5350
5351</pre>
5352<h5>Overview:</h5>
5353<p>
5354 The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between
5355 specific pairs of memory access types.
5356</p>
5357<h5>Arguments:</h5>
5358<p>
5359 The <tt>llvm.memory.barrier</tt> intrinsic requires five boolean arguments.
5360 The first four arguments enables a specific barrier as listed below. The fith
5361 argument specifies that the barrier applies to io or device or uncached memory.
5362
5363</p>
5364 <ul>
5365 <li><tt>ll</tt>: load-load barrier</li>
5366 <li><tt>ls</tt>: load-store barrier</li>
5367 <li><tt>sl</tt>: store-load barrier</li>
5368 <li><tt>ss</tt>: store-store barrier</li>
5369 <li><tt>device</tt>: barrier applies to device and uncached memory also.
5370 </ul>
5371<h5>Semantics:</h5>
5372<p>
5373 This intrinsic causes the system to enforce some ordering constraints upon
5374 the loads and stores of the program. This barrier does not indicate
5375 <em>when</em> any events will occur, it only enforces an <em>order</em> in
5376 which they occur. For any of the specified pairs of load and store operations
5377 (f.ex. load-load, or store-load), all of the first operations preceding the
5378 barrier will complete before any of the second operations succeeding the
5379 barrier begin. Specifically the semantics for each pairing is as follows:
5380</p>
5381 <ul>
5382 <li><tt>ll</tt>: All loads before the barrier must complete before any load
5383 after the barrier begins.</li>
5384
5385 <li><tt>ls</tt>: All loads before the barrier must complete before any
5386 store after the barrier begins.</li>
5387 <li><tt>ss</tt>: All stores before the barrier must complete before any
5388 store after the barrier begins.</li>
5389 <li><tt>sl</tt>: All stores before the barrier must complete before any
5390 load after the barrier begins.</li>
5391 </ul>
5392<p>
5393 These semantics are applied with a logical "and" behavior when more than one
5394 is enabled in a single memory barrier intrinsic.
5395</p>
5396<p>
5397 Backends may implement stronger barriers than those requested when they do not
5398 support as fine grained a barrier as requested. Some architectures do not
5399 need all types of barriers and on such architectures, these become noops.
5400</p>
5401<h5>Example:</h5>
5402<pre>
5403%ptr = malloc i32
5404 store i32 4, %ptr
5405
5406%result1 = load i32* %ptr <i>; yields {i32}:result1 = 4</i>
5407 call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
5408 <i>; guarantee the above finishes</i>
5409 store i32 8, %ptr <i>; before this begins</i>
5410</pre>
5411</div>
5412
Andrew Lenharthe44f3902008-02-21 06:45:13 +0000[diff] [blame]5413<!-- _______________________________________________________________________ -->
5414<div class="doc_subsubsection">
5415 <a name="int_atomic_lcs">'<tt>llvm.atomic.lcs.*</tt>' Intrinsic</a>
5416</div>
5417<div class="doc_text">
5418<h5>Syntax:</h5>
5419<p>
5420 This is an overloaded intrinsic. You can use <tt>llvm.atomic.lcs</tt> on any
5421 integer bit width. Not all targets support all bit widths however.</p>
5422
5423<pre>
5424declare i8 @llvm.atomic.lcs.i8( i8* &lt;ptr&gt;, i8 &lt;cmp&gt;, i8 &lt;val&gt; )
5425declare i16 @llvm.atomic.lcs.i16( i16* &lt;ptr&gt;, i16 &lt;cmp&gt;, i16 &lt;val&gt; )
5426declare i32 @llvm.atomic.lcs.i32( i32* &lt;ptr&gt;, i32 &lt;cmp&gt;, i32 &lt;val&gt; )
5427declare i64 @llvm.atomic.lcs.i64( i64* &lt;ptr&gt;, i64 &lt;cmp&gt;, i64 &lt;val&gt; )
5428
5429</pre>
5430<h5>Overview:</h5>
5431<p>
5432 This loads a value in memory and compares it to a given value. If they are
5433 equal, it stores a new value into the memory.
5434</p>
5435<h5>Arguments:</h5>
5436<p>
5437 The <tt>llvm.atomic.lcs</tt> intrinsic takes three arguments. The result as
5438 well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the
5439 same bit width. The <tt>ptr</tt> argument must be a pointer to a value of
5440 this integer type. While any bit width integer may be used, targets may only
5441 lower representations they support in hardware.
5442
5443</p>
5444<h5>Semantics:</h5>
5445<p>
5446 This entire intrinsic must be executed atomically. It first loads the value
5447 in memory pointed to by <tt>ptr</tt> and compares it with the value
5448 <tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the memory. The
5449 loaded value is yielded in all cases. This provides the equivalent of an
5450 atomic compare-and-swap operation within the SSA framework.
5451</p>
5452<h5>Examples:</h5>
5453
5454<pre>
5455%ptr = malloc i32
5456 store i32 4, %ptr
5457
5458%val1 = add i32 4, 4
5459%result1 = call i32 @llvm.atomic.lcs.i32( i32* %ptr, i32 4, %val1 )
5460 <i>; yields {i32}:result1 = 4</i>
5461%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
5462%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
5463
5464%val2 = add i32 1, 1
5465%result2 = call i32 @llvm.atomic.lcs.i32( i32* %ptr, i32 5, %val2 )
5466 <i>; yields {i32}:result2 = 8</i>
5467%stored2 = icmp eq i32 %result2, 5 <i>; yields {i1}:stored2 = false</i>
5468
5469%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 8</i>
5470</pre>
5471</div>
5472
5473<!-- _______________________________________________________________________ -->
5474<div class="doc_subsubsection">
5475 <a name="int_atomic_swap">'<tt>llvm.atomic.swap.*</tt>' Intrinsic</a>
5476</div>
5477<div class="doc_text">
5478<h5>Syntax:</h5>
5479
5480<p>
5481 This is an overloaded intrinsic. You can use <tt>llvm.atomic.swap</tt> on any
5482 integer bit width. Not all targets support all bit widths however.</p>
5483<pre>
5484declare i8 @llvm.atomic.swap.i8( i8* &lt;ptr&gt;, i8 &lt;val&gt; )
5485declare i16 @llvm.atomic.swap.i16( i16* &lt;ptr&gt;, i16 &lt;val&gt; )
5486declare i32 @llvm.atomic.swap.i32( i32* &lt;ptr&gt;, i32 &lt;val&gt; )
5487declare i64 @llvm.atomic.swap.i64( i64* &lt;ptr&gt;, i64 &lt;val&gt; )
5488
5489</pre>
5490<h5>Overview:</h5>
5491<p>
5492 This intrinsic loads the value stored in memory at <tt>ptr</tt> and yields
5493 the value from memory. It then stores the value in <tt>val</tt> in the memory
5494 at <tt>ptr</tt>.
5495</p>
5496<h5>Arguments:</h5>
5497
5498<p>
5499 The <tt>llvm.atomic.ls</tt> intrinsic takes two arguments. Both the
5500 <tt>val</tt> argument and the result must be integers of the same bit width.
5501 The first argument, <tt>ptr</tt>, must be a pointer to a value of this
5502 integer type. The targets may only lower integer representations they
5503 support.
5504</p>
5505<h5>Semantics:</h5>
5506<p>
5507 This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and
5508 stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the
5509 equivalent of an atomic swap operation within the SSA framework.
5510
5511</p>
5512<h5>Examples:</h5>
5513<pre>
5514%ptr = malloc i32
5515 store i32 4, %ptr
5516
5517%val1 = add i32 4, 4
5518%result1 = call i32 @llvm.atomic.swap.i32( i32* %ptr, i32 %val1 )
5519 <i>; yields {i32}:result1 = 4</i>
5520%stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
5521%memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
5522
5523%val2 = add i32 1, 1
5524%result2 = call i32 @llvm.atomic.swap.i32( i32* %ptr, i32 %val2 )
5525 <i>; yields {i32}:result2 = 8</i>
5526
5527%stored2 = icmp eq i32 %result2, 8 <i>; yields {i1}:stored2 = true</i>
5528%memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 2</i>
5529</pre>
5530</div>
5531
5532<!-- _______________________________________________________________________ -->
5533<div class="doc_subsubsection">
5534 <a name="int_atomic_las">'<tt>llvm.atomic.las.*</tt>' Intrinsic</a>
5535
5536</div>
5537<div class="doc_text">
5538<h5>Syntax:</h5>
5539<p>
5540 This is an overloaded intrinsic. You can use <tt>llvm.atomic.las</tt> on any
5541 integer bit width. Not all targets support all bit widths however.</p>
5542<pre>
5543declare i8 @llvm.atomic.las.i8.( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
5544declare i16 @llvm.atomic.las.i16.( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
5545declare i32 @llvm.atomic.las.i32.( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
5546declare i64 @llvm.atomic.las.i64.( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
5547
5548</pre>
5549<h5>Overview:</h5>
5550<p>
5551 This intrinsic adds <tt>delta</tt> to the value stored in memory at
5552 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
5553</p>
5554<h5>Arguments:</h5>
5555<p>
5556
5557 The intrinsic takes two arguments, the first a pointer to an integer value
5558 and the second an integer value. The result is also an integer value. These
5559 integer types can have any bit width, but they must all have the same bit
5560 width. The targets may only lower integer representations they support.
5561</p>
5562<h5>Semantics:</h5>
5563<p>
5564 This intrinsic does a series of operations atomically. It first loads the
5565 value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result
5566 to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
5567</p>
5568
5569<h5>Examples:</h5>
5570<pre>
5571%ptr = malloc i32
5572 store i32 4, %ptr
5573%result1 = call i32 @llvm.atomic.las.i32( i32* %ptr, i32 4 )
5574 <i>; yields {i32}:result1 = 4</i>
5575%result2 = call i32 @llvm.atomic.las.i32( i32* %ptr, i32 2 )
5576 <i>; yields {i32}:result2 = 8</i>
5577%result3 = call i32 @llvm.atomic.las.i32( i32* %ptr, i32 5 )
5578 <i>; yields {i32}:result3 = 10</i>
5579%memval = load i32* %ptr <i>; yields {i32}:memval1 = 15</i>
5580</pre>
5581</div>
5582
Andrew Lenharth785610d2008-02-16 01:24:58 +0000[diff] [blame]5583
5584<!-- ======================================================================= -->
5585<div class="doc_subsection">
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5586 <a name="int_general">General Intrinsics</a>
5587</div>
5588
5589<div class="doc_text">
5590<p> This class of intrinsics is designed to be generic and has
5591no specific purpose. </p>
5592</div>
5593
5594<!-- _______________________________________________________________________ -->
5595<div class="doc_subsubsection">
5596 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
5597</div>
5598
5599<div class="doc_text">
5600
5601<h5>Syntax:</h5>
5602<pre>
5603 declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5604</pre>
5605
5606<h5>Overview:</h5>
5607
5608<p>
5609The '<tt>llvm.var.annotation</tt>' intrinsic
5610</p>
5611
5612<h5>Arguments:</h5>
5613
5614<p>
5615The first argument is a pointer to a value, the second is a pointer to a
5616global string, the third is a pointer to a global string which is the source
5617file name, and the last argument is the line number.
5618</p>
5619
5620<h5>Semantics:</h5>
5621
5622<p>
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]5623This intrinsic allows annotation of local variables with arbitrary strings.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5624This can be useful for special purpose optimizations that want to look for these
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]5625annotations. These have no other defined use, they are ignored by code
5626generation and optimization.
5627</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5628</div>
5629
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5630<!-- _______________________________________________________________________ -->
5631<div class="doc_subsubsection">
Tanya Lattnerc9869b12007-09-21 23:57:59 +0000[diff] [blame]5632 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5633</div>
5634
5635<div class="doc_text">
5636
5637<h5>Syntax:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5638<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
5639any integer bit width.
5640</p>
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5641<pre>
Tanya Lattner09161fe2007-09-22 00:03:01 +0000[diff] [blame]5642 declare i8 @llvm.annotation.i8(i8 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5643 declare i16 @llvm.annotation.i16(i16 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5644 declare i32 @llvm.annotation.i32(i32 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5645 declare i64 @llvm.annotation.i64(i64 &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32 &lt;int&gt; )
5646 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]5647</pre>
5648
5649<h5>Overview:</h5>
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5650
5651<p>
5652The '<tt>llvm.annotation</tt>' intrinsic.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5653</p>
5654
5655<h5>Arguments:</h5>
5656
5657<p>
5658The first argument is an integer value (result of some expression),
5659the second is a pointer to a global string, the third is a pointer to a global
5660string which is the source file name, and the last argument is the line number.
Tanya Lattnere545be72007-09-21 23:56:27 +0000[diff] [blame]5661It returns the value of the first argument.
Tanya Lattnerb306a9e2007-09-21 22:59:12 +0000[diff] [blame]5662</p>
5663
5664<h5>Semantics:</h5>
5665
5666<p>
5667This intrinsic allows annotations to be put on arbitrary expressions
5668with arbitrary strings. This can be useful for special purpose optimizations
5669that want to look for these annotations. These have no other defined use, they
5670are ignored by code generation and optimization.
5671</div>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5672
Anton Korobeynikove6e764f2008-01-15 22:31:34 +0000[diff] [blame]5673<!-- _______________________________________________________________________ -->
5674<div class="doc_subsubsection">
5675 <a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
5676</div>
5677
5678<div class="doc_text">
5679
5680<h5>Syntax:</h5>
5681<pre>
5682 declare void @llvm.trap()
5683</pre>
5684
5685<h5>Overview:</h5>
5686
5687<p>
5688The '<tt>llvm.trap</tt>' intrinsic
5689</p>
5690
5691<h5>Arguments:</h5>
5692
5693<p>
5694None
5695</p>
5696
5697<h5>Semantics:</h5>
5698
5699<p>
5700This intrinsics is lowered to the target dependent trap instruction. If the
5701target does not have a trap instruction, this intrinsic will be lowered to the
5702call of the abort() function.
5703</p>
5704</div>
5705
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5706<!-- *********************************************************************** -->
5707<hr>
5708<address>
5709 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
5710 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
5711 <a href="http://validator.w3.org/check/referer"><img
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]5712 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5713
5714 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
5715 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
5716 Last modified: $Date$
5717</address>
Chris Lattner08497ce2008-01-04 04:33:49 +0000[diff] [blame]5718
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]5719</body>
5720</html>