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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 3689a34489224a71c6306f55ce0718014c3b01cf / . / docs / LangRef.html
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4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
Reid Spencer3921c742004-08-26 20:44:00 +0000[diff] [blame]6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]24 <li><a href="#globalvars">Global Variables</a></li>
25 <li><a href="#functionstructure">Function Structure</a></li>
26 </ol>
27 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]28 <li><a href="#typesystem">Type System</a>
29 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]30 <li><a href="#t_primitive">Primitive Types</a>
31 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]32 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]33 </ol>
34 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]35 <li><a href="#t_derived">Derived Types</a>
36 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]37 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]38 <li><a href="#t_function">Function Type</a></li>
39 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]40 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]41 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]42 </ol>
43 </li>
44 </ol>
45 </li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]46 <li><a href="#constants">Constants</a>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]47 <ol>
48 <li><a href="#simpleconstants">Simple Constants</a>
49 <li><a href="#aggregateconstants">Aggregate Constants</a>
50 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
51 <li><a href="#undefvalues">Undefined Values</a>
52 <li><a href="#constantexprs">Constant Expressions</a>
53 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]54 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]55 <li><a href="#instref">Instruction Reference</a>
56 <ol>
57 <li><a href="#terminators">Terminator Instructions</a>
58 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]59 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
60 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]61 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
62 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]63 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]64 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]65 </ol>
66 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]67 <li><a href="#binaryops">Binary Operations</a>
68 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]69 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
70 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
71 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
72 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
73 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]74 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]75 </ol>
76 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]77 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
78 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]79 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]80 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]81 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
82 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
83 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]84 </ol>
85 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]86 <li><a href="#memoryops">Memory Access Operations</a>
87 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]88 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
89 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
90 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
91 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
92 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
93 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
94 </ol>
95 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]96 <li><a href="#otherops">Other Operations</a>
97 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]98 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]99 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]100 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]101 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]102 <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]103 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]104 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]105 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]106 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]107 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]108 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]109 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]110 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
111 <ol>
112 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
113 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
114 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
115 </ol>
116 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]117 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
118 <ol>
119 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
120 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
121 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
122 </ol>
123 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]124 <li><a href="#int_codegen">Code Generator Intrinsics</a>
125 <ol>
126 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
127 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]128 </ol>
129 </li>
130 <li><a href="#int_os">Operating System Intrinsics</a>
131 <ol>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]132 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
133 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]134 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
135 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]136 </ol>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]137 <li><a href="#int_libc">Standard C Library Intrinsics</a>
138 <ol>
139 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]140 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]141 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos96853722004-06-12 19:19:14 +0000[diff] [blame]142 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]143 </ol>
144 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]145 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]146 </ol>
147 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]148</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]149
150<div class="doc_author">
151 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
152 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]153</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]154
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]155<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]156<div class="doc_section"> <a name="abstract">Abstract </a></div>
157<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]158
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]159<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]160<p>This document is a reference manual for the LLVM assembly language.
161LLVM is an SSA based representation that provides type safety,
162low-level operations, flexibility, and the capability of representing
163'all' high-level languages cleanly. It is the common code
164representation used throughout all phases of the LLVM compilation
165strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]166</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]167
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]168<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]169<div class="doc_section"> <a name="introduction">Introduction</a> </div>
170<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]171
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]172<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]173
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]174<p>The LLVM code representation is designed to be used in three
175different forms: as an in-memory compiler IR, as an on-disk bytecode
176representation (suitable for fast loading by a Just-In-Time compiler),
177and as a human readable assembly language representation. This allows
178LLVM to provide a powerful intermediate representation for efficient
179compiler transformations and analysis, while providing a natural means
180to debug and visualize the transformations. The three different forms
181of LLVM are all equivalent. This document describes the human readable
182representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]183
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]184<p>The LLVM representation aims to be a light-weight and low-level
185while being expressive, typed, and extensible at the same time. It
186aims to be a "universal IR" of sorts, by being at a low enough level
187that high-level ideas may be cleanly mapped to it (similar to how
188microprocessors are "universal IR's", allowing many source languages to
189be mapped to them). By providing type information, LLVM can be used as
190the target of optimizations: for example, through pointer analysis, it
191can be proven that a C automatic variable is never accessed outside of
192the current function... allowing it to be promoted to a simple SSA
193value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]194
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]195</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]196
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]197<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]198<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]199
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]200<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]201
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]202<p>It is important to note that this document describes 'well formed'
203LLVM assembly language. There is a difference between what the parser
204accepts and what is considered 'well formed'. For example, the
205following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]206
207<pre>
208 %x = <a href="#i_add">add</a> int 1, %x
209</pre>
210
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]211<p>...because the definition of <tt>%x</tt> does not dominate all of
212its uses. The LLVM infrastructure provides a verification pass that may
213be used to verify that an LLVM module is well formed. This pass is
214automatically run by the parser after parsing input assembly, and by
215the optimizer before it outputs bytecode. The violations pointed out
216by the verifier pass indicate bugs in transformation passes or input to
217the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]218
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]219<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]220
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]221<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]222<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]223<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]224
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]225<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]226
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]227<p>LLVM uses three different forms of identifiers, for different
228purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]229
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]230<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]231 <li>Named values are represented as a string of characters with a '%' prefix.
232 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
233 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
234 Identifiers which require other characters in their names can be surrounded
235 with quotes. In this way, anything except a <tt>"</tt> character can be used
236 in a name.</li>
237
238 <li>Unnamed values are represented as an unsigned numeric value with a '%'
239 prefix. For example, %12, %2, %44.</li>
240
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]241 <li>Constants, which are described in a <a href="#constants">section about
242 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]243</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]244
245<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
246don't need to worry about name clashes with reserved words, and the set of
247reserved words may be expanded in the future without penalty. Additionally,
248unnamed identifiers allow a compiler to quickly come up with a temporary
249variable without having to avoid symbol table conflicts.</p>
250
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]251<p>Reserved words in LLVM are very similar to reserved words in other
252languages. There are keywords for different opcodes ('<tt><a
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]253href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
254href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
255href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
256and others. These reserved words cannot conflict with variable names, because
257none of them start with a '%' character.</p>
258
259<p>Here is an example of LLVM code to multiply the integer variable
260'<tt>%X</tt>' by 8:</p>
261
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]262<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]263
264<pre>
265 %result = <a href="#i_mul">mul</a> uint %X, 8
266</pre>
267
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]268<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]269
270<pre>
271 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
272</pre>
273
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]274<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]275
276<pre>
277 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
278 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
279 %result = <a href="#i_add">add</a> uint %1, %1
280</pre>
281
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]282<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
283important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]284
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]285<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]286
287 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
288 line.</li>
289
290 <li>Unnamed temporaries are created when the result of a computation is not
291 assigned to a named value.</li>
292
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]293 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]294
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]295</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]296
297<p>...and it also show a convention that we follow in this document. When
298demonstrating instructions, we will follow an instruction with a comment that
299defines the type and name of value produced. Comments are shown in italic
300text.</p>
301
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]302</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]303
304<!-- *********************************************************************** -->
305<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
306<!-- *********************************************************************** -->
307
308<!-- ======================================================================= -->
309<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
310</div>
311
312<div class="doc_text">
313
314<p>LLVM programs are composed of "Module"s, each of which is a
315translation unit of the input programs. Each module consists of
316functions, global variables, and symbol table entries. Modules may be
317combined together with the LLVM linker, which merges function (and
318global variable) definitions, resolves forward declarations, and merges
319symbol table entries. Here is an example of the "hello world" module:</p>
320
321<pre><i>; Declare the string constant as a global constant...</i>
322<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
323 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
324
325<i>; External declaration of the puts function</i>
326<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
327
328<i>; Definition of main function</i>
329int %main() { <i>; int()* </i>
330 <i>; Convert [13x sbyte]* to sbyte *...</i>
331 %cast210 = <a
332 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
333
334 <i>; Call puts function to write out the string to stdout...</i>
335 <a
336 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
337 <a
338 href="#i_ret">ret</a> int 0<br>}<br></pre>
339
340<p>This example is made up of a <a href="#globalvars">global variable</a>
341named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
342function, and a <a href="#functionstructure">function definition</a>
343for "<tt>main</tt>".</p>
344
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]345<p>In general, a module is made up of a list of global values,
346where both functions and global variables are global values. Global values are
347represented by a pointer to a memory location (in this case, a pointer to an
348array of char, and a pointer to a function), and have one of the following <a
349href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]350
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]351</div>
352
353<!-- ======================================================================= -->
354<div class="doc_subsection">
355 <a name="linkage">Linkage Types</a>
356</div>
357
358<div class="doc_text">
359
360<p>
361All Global Variables and Functions have one of the following types of linkage:
362</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]363
364<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]365
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]366 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]367
368 <dd>Global values with internal linkage are only directly accessible by
369 objects in the current module. In particular, linking code into a module with
370 an internal global value may cause the internal to be renamed as necessary to
371 avoid collisions. Because the symbol is internal to the module, all
372 references can be updated. This corresponds to the notion of the
373 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]374 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]375
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]376 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]377
378 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
379 the twist that linking together two modules defining the same
380 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
381 is typically used to implement inline functions. Unreferenced
382 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]383 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]384
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]385 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]386
387 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
388 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
389 used to implement constructs in C such as "<tt>int X;</tt>" at global scope.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]390 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]391
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]392 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]393
394 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
395 pointer to array type. When two global variables with appending linkage are
396 linked together, the two global arrays are appended together. This is the
397 LLVM, typesafe, equivalent of having the system linker append together
398 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]399 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]400
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]401 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]402
403 <dd>If none of the above identifiers are used, the global is externally
404 visible, meaning that it participates in linkage and can be used to resolve
405 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]406 </dd>
407</dl>
408
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]409<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
410variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
411variable and was linked with this one, one of the two would be renamed,
412preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
413external (i.e., lacking any linkage declarations), they are accessible
414outside of the current module. It is illegal for a function <i>declaration</i>
415to have any linkage type other than "externally visible".</a></p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]416
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]417</div>
418
419<!-- ======================================================================= -->
420<div class="doc_subsection">
421 <a name="globalvars">Global Variables</a>
422</div>
423
424<div class="doc_text">
425
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame^]426<p>Global variables define regions of memory allocated at compilation time
427instead of run-time. Global variables may optionally be initialized. A
428variable may be defined as a global "constant", which indicates that the
429contents of the variable will <b>never</b> be modified (enabling better
430optimization, allowing the global data to be placed in the read-only section of
431an executable, etc). Note that variables that need runtime initialization
432cannot be marked "constant", as there is a store to the variable.</p>
433
434<p>
435LLVM explicitly allows <em>declarations</em> of global variables to be marked
436constant, even if the final definition of the global is not. This capability
437can be used to enable slightly better optimization of the program, but requires
438the language definition to guarantee that optimizations based on the
439'constantness' are valid for the translation units that do not include the
440definition.
441</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]442
443<p>As SSA values, global variables define pointer values that are in
444scope (i.e. they dominate) all basic blocks in the program. Global
445variables always define a pointer to their "content" type because they
446describe a region of memory, and all memory objects in LLVM are
447accessed through pointers.</p>
448
449</div>
450
451
452<!-- ======================================================================= -->
453<div class="doc_subsection">
454 <a name="functionstructure">Functions</a>
455</div>
456
457<div class="doc_text">
458
459<p>LLVM function definitions are composed of a (possibly empty) argument list,
460an opening curly brace, a list of basic blocks, and a closing curly brace. LLVM
461function declarations are defined with the "<tt>declare</tt>" keyword, a
462function name, and a function signature.</p>
463
464<p>A function definition contains a list of basic blocks, forming the CFG for
465the function. Each basic block may optionally start with a label (giving the
466basic block a symbol table entry), contains a list of instructions, and ends
467with a <a href="#terminators">terminator</a> instruction (such as a branch or
468function return).</p>
469
470<p>The first basic block in program is special in two ways: it is immediately
471executed on entrance to the function, and it is not allowed to have predecessor
472basic blocks (i.e. there can not be any branches to the entry block of a
473function). Because the block can have no predecessors, it also cannot have any
474<a href="#i_phi">PHI nodes</a>.</p>
475
476<p>LLVM functions are identified by their name and type signature. Hence, two
477functions with the same name but different parameter lists or return values are
478considered different functions, and LLVM will resolves references to each
479appropriately.</p>
480
481</div>
482
483
484
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]485<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]486<div class="doc_section"> <a name="typesystem">Type System</a> </div>
487<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]488
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]489<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]490
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]491<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]492intermediate representation. Being typed enables a number of
493optimizations to be performed on the IR directly, without having to do
494extra analyses on the side before the transformation. A strong type
495system makes it easier to read the generated code and enables novel
496analyses and transformations that are not feasible to perform on normal
497three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]498
499</div>
500
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]501<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]502<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]503<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]504<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]505system. The current set of primitive types are as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]506
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]507<table class="layout">
508 <tr class="layout">
509 <td class="left">
510 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]511 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]512 <tr><th>Type</th><th>Description</th></tr>
513 <tr><td><tt>void</tt></td><td>No value</td></tr>
514 <tr><td><tt>ubyte</tt></td><td>Unsigned 8 bit value</td></tr>
515 <tr><td><tt>ushort</tt></td><td>Unsigned 16 bit value</td></tr>
516 <tr><td><tt>uint</tt></td><td>Unsigned 32 bit value</td></tr>
517 <tr><td><tt>ulong</tt></td><td>Unsigned 64 bit value</td></tr>
518 <tr><td><tt>float</tt></td><td>32 bit floating point value</td></tr>
519 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]520 </tbody>
521 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]522 </td>
523 <td class="right">
524 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]525 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]526 <tr><th>Type</th><th>Description</th></tr>
527 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
528 <tr><td><tt>sbyte</tt></td><td>Signed 8 bit value</td></tr>
529 <tr><td><tt>short</tt></td><td>Signed 16 bit value</td></tr>
530 <tr><td><tt>int</tt></td><td>Signed 32 bit value</td></tr>
531 <tr><td><tt>long</tt></td><td>Signed 64 bit value</td></tr>
532 <tr><td><tt>double</tt></td><td>64 bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]533 </tbody>
534 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]535 </td>
536 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]537</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]538</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]539
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]540<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]541<div class="doc_subsubsection"> <a name="t_classifications">Type
542Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]543<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]544<p>These different primitive types fall into a few useful
545classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]546
547<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]548 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]549 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]550 <tr>
551 <td><a name="t_signed">signed</a></td>
552 <td><tt>sbyte, short, int, long, float, double</tt></td>
553 </tr>
554 <tr>
555 <td><a name="t_unsigned">unsigned</a></td>
556 <td><tt>ubyte, ushort, uint, ulong</tt></td>
557 </tr>
558 <tr>
559 <td><a name="t_integer">integer</a></td>
560 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
561 </tr>
562 <tr>
563 <td><a name="t_integral">integral</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]564 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
565 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]566 </tr>
567 <tr>
568 <td><a name="t_floating">floating point</a></td>
569 <td><tt>float, double</tt></td>
570 </tr>
571 <tr>
572 <td><a name="t_firstclass">first class</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]573 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
574 float, double, <a href="#t_pointer">pointer</a>,
575 <a href="#t_packed">packed</a></tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]576 </tr>
577 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]578</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]579
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]580<p>The <a href="#t_firstclass">first class</a> types are perhaps the
581most important. Values of these types are the only ones which can be
582produced by instructions, passed as arguments, or used as operands to
583instructions. This means that all structures and arrays must be
584manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]585</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]586
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]587<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]588<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]589
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]590<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]591
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]592<p>The real power in LLVM comes from the derived types in the system.
593This is what allows a programmer to represent arrays, functions,
594pointers, and other useful types. Note that these derived types may be
595recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]596
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]597</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]598
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]599<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]600<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]601
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]602<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]603
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]604<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]605
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]606<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]607sequentially in memory. The array type requires a size (number of
608elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]609
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]610<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]611
612<pre>
613 [&lt;# elements&gt; x &lt;elementtype&gt;]
614</pre>
615
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]616<p>The number of elements is a constant integer value, elementtype may
617be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]618
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]619<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]620<table class="layout">
621 <tr class="layout">
622 <td class="left">
623 <tt>[40 x int ]</tt><br/>
624 <tt>[41 x int ]</tt><br/>
625 <tt>[40 x uint]</tt><br/>
626 </td>
627 <td class="left">
628 Array of 40 integer values.<br/>
629 Array of 41 integer values.<br/>
630 Array of 40 unsigned integer values.<br/>
631 </td>
632 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]633</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]634<p>Here are some examples of multidimensional arrays:</p>
635<table class="layout">
636 <tr class="layout">
637 <td class="left">
638 <tt>[3 x [4 x int]]</tt><br/>
639 <tt>[12 x [10 x float]]</tt><br/>
640 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
641 </td>
642 <td class="left">
643 3x4 array integer values.<br/>
644 12x10 array of single precision floating point values.<br/>
645 2x3x4 array of unsigned integer values.<br/>
646 </td>
647 </tr>
648</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]649</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]650
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]651<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]652<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]653<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]654<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]655<p>The function type can be thought of as a function signature. It
656consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]657Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]658(which are structures of pointers to functions), for indirect function
659calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]660<p>
661The return type of a function type cannot be an aggregate type.
662</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]663<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]664<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]665<p>Where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
666specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]667which indicates that the function takes a variable number of arguments.
668Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]669 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]670<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]671<table class="layout">
672 <tr class="layout">
673 <td class="left">
674 <tt>int (int)</tt> <br/>
675 <tt>float (int, int *) *</tt><br/>
676 <tt>int (sbyte *, ...)</tt><br/>
677 </td>
678 <td class="left">
679 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
680 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]681 <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]682 returning <tt>float</tt>.<br/>
683 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
684 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
685 the signature for <tt>printf</tt> in LLVM.<br/>
686 </td>
687 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]688</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]689
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]690</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]691<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]692<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]693<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]694<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]695<p>The structure type is used to represent a collection of data members
696together in memory. The packing of the field types is defined to match
697the ABI of the underlying processor. The elements of a structure may
698be any type that has a size.</p>
699<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
700and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
701field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
702instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]703<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]704<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]705<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]706<table class="layout">
707 <tr class="layout">
708 <td class="left">
709 <tt>{ int, int, int }</tt><br/>
710 <tt>{ float, int (int) * }</tt><br/>
711 </td>
712 <td class="left">
713 a triple of three <tt>int</tt> values<br/>
714 A pair, where the first element is a <tt>float</tt> and the second element
715 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
716 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
717 </td>
718 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]719</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]720</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]721
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]722<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]723<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]724<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]725<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]726<p>As in many languages, the pointer type represents a pointer or
727reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]728<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]729<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]730<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]731<table class="layout">
732 <tr class="layout">
733 <td class="left">
734 <tt>[4x int]*</tt><br/>
735 <tt>int (int *) *</tt><br/>
736 </td>
737 <td class="left">
738 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
739 four <tt>int</tt> values<br/>
740 A <a href="#t_pointer">pointer</a> to a <a
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]741 href="#t_function">function</a> that takes an <tt>int</tt>, returning an
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]742 <tt>int</tt>.<br/>
743 </td>
744 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]745</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]746</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]747
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]748<!-- _______________________________________________________________________ -->
749<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]750<div class="doc_text">
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]751<h5>Overview:</h5>
752<p>A packed type is a simple derived type that represents a vector
753of elements. Packed types are used when multiple primitive data
754are operated in parallel using a single instruction (SIMD).
755A packed type requires a size (number of
756elements) and an underlying primitive data type. Packed types are
757considered <a href="#t_firstclass">first class</a>.</p>
758<h5>Syntax:</h5>
759<pre> &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;<br></pre>
760<p>The number of elements is a constant integer value, elementtype may
761be any integral or floating point type.</p>
762<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]763<table class="layout">
764 <tr class="layout">
765 <td class="left">
766 <tt>&lt;4 x int&gt;</tt><br/>
767 <tt>&lt;8 x float&gt;</tt><br/>
768 <tt>&lt;2 x uint&gt;</tt><br/>
769 </td>
770 <td class="left">
771 Packed vector of 4 integer values.<br/>
772 Packed vector of 8 floating-point values.<br/>
773 Packed vector of 2 unsigned integer values.<br/>
774 </td>
775 </tr>
776</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]777</div>
778
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]779<!-- *********************************************************************** -->
780<div class="doc_section"> <a name="constants">Constants</a> </div>
781<!-- *********************************************************************** -->
782
783<div class="doc_text">
784
785<p>LLVM has several different basic types of constants. This section describes
786them all and their syntax.</p>
787
788</div>
789
790<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]791<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]792
793<div class="doc_text">
794
795<dl>
796 <dt><b>Boolean constants</b></dt>
797
798 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
799 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
800 </dd>
801
802 <dt><b>Integer constants</b></dt>
803
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]804 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]805 href="#t_integer">integer</a> type. Negative numbers may be used with signed
806 integer types.
807 </dd>
808
809 <dt><b>Floating point constants</b></dt>
810
811 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
812 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]813 notation. Floating point constants have an optional hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]814 notation (see below). Floating point constants must have a <a
815 href="#t_floating">floating point</a> type. </dd>
816
817 <dt><b>Null pointer constants</b></dt>
818
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]819 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]820 and must be of <a href="#t_pointer">pointer type</a>.</dd>
821
822</dl>
823
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]824<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]825of floating point constants. For example, the form '<tt>double
8260x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
8274.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]828(and the only time that they are generated by the disassembler) is when a
829floating point constant must be emitted but it cannot be represented as a
830decimal floating point number. For example, NaN's, infinities, and other
831special values are represented in their IEEE hexadecimal format so that
832assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]833
834</div>
835
836<!-- ======================================================================= -->
837<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
838</div>
839
840<div class="doc_text">
841
842<dl>
843 <dt><b>Structure constants</b></dt>
844
845 <dd>Structure constants are represented with notation similar to structure
846 type definitions (a comma separated list of elements, surrounded by braces
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]847 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0 }</tt>". Structure
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]848 constants must have <a href="#t_struct">structure type</a>, and the number and
849 types of elements must match those specified by the type.
850 </dd>
851
852 <dt><b>Array constants</b></dt>
853
854 <dd>Array constants are represented with notation similar to array type
855 definitions (a comma separated list of elements, surrounded by square brackets
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]856 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]857 constants must have <a href="#t_array">array type</a>, and the number and
858 types of elements must match those specified by the type.
859 </dd>
860
861 <dt><b>Packed constants</b></dt>
862
863 <dd>Packed constants are represented with notation similar to packed type
864 definitions (a comma separated list of elements, surrounded by
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]865 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; int 42,
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]866 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
867 href="#t_packed">packed type</a>, and the number and types of elements must
868 match those specified by the type.
869 </dd>
870
871 <dt><b>Zero initialization</b></dt>
872
873 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
874 value to zero of <em>any</em> type, including scalar and aggregate types.
875 This is often used to avoid having to print large zero initializers (e.g. for
876 large arrays), and is always exactly equivalent to using explicit zero
877 initializers.
878 </dd>
879</dl>
880
881</div>
882
883<!-- ======================================================================= -->
884<div class="doc_subsection">
885 <a name="globalconstants">Global Variable and Function Addresses</a>
886</div>
887
888<div class="doc_text">
889
890<p>The addresses of <a href="#globalvars">global variables</a> and <a
891href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]892constants. These constants are explicitly referenced when the <a
893href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]894href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
895file:</p>
896
897<pre>
898 %X = global int 17
899 %Y = global int 42
900 %Z = global [2 x int*] [ int* %X, int* %Y ]
901</pre>
902
903</div>
904
905<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]906<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]907<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]908 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
909 no specific value. Undefined values may be of any type, and be used anywhere
910 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]911
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]912 <p>Undefined values indicate to the compiler that the program is well defined
913 no matter what value is used, giving the compiler more freedom to optimize.
914 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]915</div>
916
917<!-- ======================================================================= -->
918<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
919</div>
920
921<div class="doc_text">
922
923<p>Constant expressions are used to allow expressions involving other constants
924to be used as constants. Constant expressions may be of any <a
925href="#t_firstclass">first class</a> type, and may involve any LLVM operation
926that does not have side effects (e.g. load and call are not supported). The
927following is the syntax for constant expressions:</p>
928
929<dl>
930 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
931
932 <dd>Cast a constant to another type.</dd>
933
934 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
935
936 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
937 constants. As with the <a href="#i_getelementptr">getelementptr</a>
938 instruction, the index list may have zero or more indexes, which are required
939 to make sense for the type of "CSTPTR".</dd>
940
941 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
942
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]943 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
944 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]945 binary</a> operations. The constraints on operands are the same as those for
946 the corresponding instruction (e.g. no bitwise operations on floating point
947 are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]948</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]949</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]950
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]951<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]952<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
953<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]954
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]955<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]956
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]957<p>The LLVM instruction set consists of several different
958classifications of instructions: <a href="#terminators">terminator
959instructions</a>, <a href="#binaryops">binary instructions</a>, <a
960 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
961instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]962
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]963</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]964
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]965<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]966<div class="doc_subsection"> <a name="terminators">Terminator
967Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]968
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]969<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]970
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]971<p>As mentioned <a href="#functionstructure">previously</a>, every
972basic block in a program ends with a "Terminator" instruction, which
973indicates which block should be executed after the current block is
974finished. These terminator instructions typically yield a '<tt>void</tt>'
975value: they produce control flow, not values (the one exception being
976the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]977<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]978 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
979instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]980the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
981 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
982 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]983
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]984</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]985
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]986<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]987<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
988Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]989<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]990<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]991<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]992 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]993</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]994<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]995<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
996value) from a function, back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]997<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]998returns a value and then causes control flow, and one that just causes
999control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1000<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1001<p>The '<tt>ret</tt>' instruction may return any '<a
1002 href="#t_firstclass">first class</a>' type. Notice that a function is
1003not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1004instruction inside of the function that returns a value that does not
1005match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1006<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1007<p>When the '<tt>ret</tt>' instruction is executed, control flow
1008returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1009 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1010the instruction after the call. If the caller was an "<a
1011 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1012at the beginning "normal" of the destination block. If the instruction
1013returns a value, that value shall set the call or invoke instruction's
1014return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1015<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1016<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1017 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1018</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1019</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1020<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1021<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1022<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1023<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1024<pre> br bool &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1025</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1026<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1027<p>The '<tt>br</tt>' instruction is used to cause control flow to
1028transfer to a different basic block in the current function. There are
1029two forms of this instruction, corresponding to a conditional branch
1030and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1031<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1032<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1033single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1034unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1035value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1036<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1037<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1038argument is evaluated. If the value is <tt>true</tt>, control flows
1039to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1040control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1041<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1042<pre>Test:<br> %cond = <a href="#i_setcc">seteq</a> int %a, %b<br> br bool %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
1043 href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1044</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1045<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1046<div class="doc_subsubsection">
1047 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1048</div>
1049
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1050<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1051<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1052
1053<pre>
1054 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1055</pre>
1056
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1057<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1058
1059<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1060several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1061instruction, allowing a branch to occur to one of many possible
1062destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1063
1064
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1065<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1066
1067<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1068comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1069an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1070table is not allowed to contain duplicate constant entries.</p>
1071
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1072<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1073
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1074<p>The <tt>switch</tt> instruction specifies a table of values and
1075destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1076table is searched for the given value. If the value is found, control flow is
1077transfered to the corresponding destination; otherwise, control flow is
1078transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1079
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1080<h5>Implementation:</h5>
1081
1082<p>Depending on properties of the target machine and the particular
1083<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1084ways. For example, it could be generated as a series of chained conditional
1085branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1086
1087<h5>Example:</h5>
1088
1089<pre>
1090 <i>; Emulate a conditional br instruction</i>
1091 %Val = <a href="#i_cast">cast</a> bool %value to int
1092 switch int %Val, label %truedest [int 0, label %falsedest ]
1093
1094 <i>; Emulate an unconditional br instruction</i>
1095 switch uint 0, label %dest [ ]
1096
1097 <i>; Implement a jump table:</i>
1098 switch uint %val, label %otherwise [ uint 0, label %onzero
1099 uint 1, label %onone
1100 uint 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1101</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1102</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1103<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1104<div class="doc_subsubsection"> <a name="i_invoke">'<tt>invoke</tt>'
1105Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1106<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1107<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1108<pre> &lt;result&gt; = invoke &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)<br> to label &lt;normal label&gt; except label &lt;exception label&gt;<br></pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1109<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1110<p>The '<tt>invoke</tt>' instruction causes control to transfer to a
1111specified function, with the possibility of control flow transfer to
1112either the '<tt>normal</tt>' <tt>label</tt> label or the '<tt>exception</tt>'<tt>label</tt>.
1113If the callee function returns with the "<tt><a href="#i_ret">ret</a></tt>"
1114instruction, control flow will return to the "normal" label. If the
1115callee (or any indirect callees) returns with the "<a href="#i_unwind"><tt>unwind</tt></a>"
1116instruction, control is interrupted, and continued at the dynamically
1117nearest "except" label.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1118<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1119<p>This instruction requires several arguments:</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1120<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1121 <li>'<tt>ptr to function ty</tt>': shall be the signature of the
1122pointer to function value being invoked. In most cases, this is a
1123direct function invocation, but indirect <tt>invoke</tt>s are just as
1124possible, branching off an arbitrary pointer to function value. </li>
1125 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer
1126to a function to be invoked. </li>
1127 <li>'<tt>function args</tt>': argument list whose types match the
1128function signature argument types. If the function signature indicates
1129the function accepts a variable number of arguments, the extra
1130arguments can be specified. </li>
1131 <li>'<tt>normal label</tt>': the label reached when the called
1132function executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1133 <li>'<tt>exception label</tt>': the label reached when a callee
1134returns with the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1135</ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1136<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1137<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1138 href="#i_call">call</a></tt>' instruction in most regards. The
1139primary difference is that it establishes an association with a label,
1140which is used by the runtime library to unwind the stack.</p>
1141<p>This instruction is used in languages with destructors to ensure
1142that proper cleanup is performed in the case of either a <tt>longjmp</tt>
1143or a thrown exception. Additionally, this is important for
1144implementation of '<tt>catch</tt>' clauses in high-level languages that
1145support them.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1146<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1147<pre> %retval = invoke int %Test(int 15)<br> to label %Continue<br> except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1148</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1149</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1150
1151
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1152<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1153
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1154<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1155Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1156
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1157<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1158
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1159<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1160<pre>
1161 unwind
1162</pre>
1163
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1164<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1165
1166<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1167at the first callee in the dynamic call stack which used an <a
1168href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1169primarily used to implement exception handling.</p>
1170
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1171<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1172
1173<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1174immediately halt. The dynamic call stack is then searched for the first <a
1175href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1176execution continues at the "exceptional" destination block specified by the
1177<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1178dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1179</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1180
1181<!-- _______________________________________________________________________ -->
1182
1183<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1184Instruction</a> </div>
1185
1186<div class="doc_text">
1187
1188<h5>Syntax:</h5>
1189<pre>
1190 unreachable
1191</pre>
1192
1193<h5>Overview:</h5>
1194
1195<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1196instruction is used to inform the optimizer that a particular portion of the
1197code is not reachable. This can be used to indicate that the code after a
1198no-return function cannot be reached, and other facts.</p>
1199
1200<h5>Semantics:</h5>
1201
1202<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1203</div>
1204
1205
1206
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1207<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1208<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1209<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1210<p>Binary operators are used to do most of the computation in a
1211program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1212produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1213multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1214The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1215necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1216<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1217</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1218<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1219<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1220Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1221<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1222<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1223<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1224</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1225<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1226<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1227<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1228<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1229 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1230 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1231Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1232<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1233<p>The value produced is the integer or floating point sum of the two
1234operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1235<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1236<pre> &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1237</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1238</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1239<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1240<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1241Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1242<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1243<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1244<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1245</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1246<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1247<p>The '<tt>sub</tt>' instruction returns the difference of its two
1248operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1249<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1250instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1251<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1252<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1253 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1254values.
1255This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1256Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1257<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1258<p>The value produced is the integer or floating point difference of
1259the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1260<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1261<pre> &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1262 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1263</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1264</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1265<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1266<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1267Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1268<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1269<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1270<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1271</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1272<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1273<p>The '<tt>mul</tt>' instruction returns the product of its two
1274operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1275<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1276<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1277 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1278values.
1279This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1280Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1281<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1282<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1283two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1284<p>There is no signed vs unsigned multiplication. The appropriate
1285action is taken based on the type of the operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1286<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1287<pre> &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1288</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1289</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1290<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1291<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1292Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1293<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1294<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1295<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1296</pre>
1297<h5>Overview:</h5>
1298<p>The '<tt>div</tt>' instruction returns the quotient of its two
1299operands.</p>
1300<h5>Arguments:</h5>
1301<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1302 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1303values.
1304This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1305Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1306<h5>Semantics:</h5>
1307<p>The value produced is the integer or floating point quotient of the
1308two operands.</p>
1309<h5>Example:</h5>
1310<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1311</pre>
1312</div>
1313<!-- _______________________________________________________________________ -->
1314<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1315Instruction</a> </div>
1316<div class="doc_text">
1317<h5>Syntax:</h5>
1318<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1319</pre>
1320<h5>Overview:</h5>
1321<p>The '<tt>rem</tt>' instruction returns the remainder from the
1322division of its two operands.</p>
1323<h5>Arguments:</h5>
1324<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1325 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1326values.
1327This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1328Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1329<h5>Semantics:</h5>
1330<p>This returns the <i>remainder</i> of a division (where the result
1331has the same sign as the divisor), not the <i>modulus</i> (where the
1332result has the same sign as the dividend) of a value. For more
1333information about the difference, see: <a
1334 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1335Math Forum</a>.</p>
1336<h5>Example:</h5>
1337<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1338</pre>
1339</div>
1340<!-- _______________________________________________________________________ -->
1341<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1342Instructions</a> </div>
1343<div class="doc_text">
1344<h5>Syntax:</h5>
1345<pre> &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1346 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1347 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1348 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1349 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1350 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1351</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1352<h5>Overview:</h5>
1353<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1354value based on a comparison of their two operands.</p>
1355<h5>Arguments:</h5>
1356<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1357be of <a href="#t_firstclass">first class</a> type (it is not possible
1358to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1359or '<tt>void</tt>' values, etc...). Both arguments must have identical
1360types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1361<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1362<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1363value if both operands are equal.<br>
1364The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1365value if both operands are unequal.<br>
1366The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1367value if the first operand is less than the second operand.<br>
1368The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1369value if the first operand is greater than the second operand.<br>
1370The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1371value if the first operand is less than or equal to the second operand.<br>
1372The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1373value if the first operand is greater than or equal to the second
1374operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1375<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1376<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1377 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1378 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1379 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1380 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1381 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1382</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1383</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1384<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1385<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1386Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1387<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1388<p>Bitwise binary operators are used to do various forms of
1389bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1390instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1391instructions. They require two operands, execute an operation on them,
1392and produce a single value. The resulting value of the bitwise binary
1393operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1394</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1395<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1396<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1397Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1398<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1399<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1400<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1401</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1402<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1403<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1404its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1405<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1406<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1407 href="#t_integral">integral</a> values. Both arguments must have
1408identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1409<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1410<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1411<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1412<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1413<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1414 <tbody>
1415 <tr>
1416 <td>In0</td>
1417 <td>In1</td>
1418 <td>Out</td>
1419 </tr>
1420 <tr>
1421 <td>0</td>
1422 <td>0</td>
1423 <td>0</td>
1424 </tr>
1425 <tr>
1426 <td>0</td>
1427 <td>1</td>
1428 <td>0</td>
1429 </tr>
1430 <tr>
1431 <td>1</td>
1432 <td>0</td>
1433 <td>0</td>
1434 </tr>
1435 <tr>
1436 <td>1</td>
1437 <td>1</td>
1438 <td>1</td>
1439 </tr>
1440 </tbody>
1441</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1442</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1443<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1444<pre> &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 &amp; %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1445 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1446 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1447</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1448</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1449<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1450<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1451<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1452<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1453<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1454</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1455<h5>Overview:</h5>
1456<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1457or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1458<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1459<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1460 href="#t_integral">integral</a> values. Both arguments must have
1461identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1462<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1463<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1464<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1465<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1466<table border="1" cellspacing="0" cellpadding="4">
1467 <tbody>
1468 <tr>
1469 <td>In0</td>
1470 <td>In1</td>
1471 <td>Out</td>
1472 </tr>
1473 <tr>
1474 <td>0</td>
1475 <td>0</td>
1476 <td>0</td>
1477 </tr>
1478 <tr>
1479 <td>0</td>
1480 <td>1</td>
1481 <td>1</td>
1482 </tr>
1483 <tr>
1484 <td>1</td>
1485 <td>0</td>
1486 <td>1</td>
1487 </tr>
1488 <tr>
1489 <td>1</td>
1490 <td>1</td>
1491 <td>1</td>
1492 </tr>
1493 </tbody>
1494</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1495</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1496<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1497<pre> &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1498 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1499 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1500</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1501</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1502<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1503<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1504Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1505<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1506<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1507<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1508</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1509<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1510<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1511or of its two operands. The <tt>xor</tt> is used to implement the
1512"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1513<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1514<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1515 href="#t_integral">integral</a> values. Both arguments must have
1516identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1517<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1518<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1519<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1520<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1521<table border="1" cellspacing="0" cellpadding="4">
1522 <tbody>
1523 <tr>
1524 <td>In0</td>
1525 <td>In1</td>
1526 <td>Out</td>
1527 </tr>
1528 <tr>
1529 <td>0</td>
1530 <td>0</td>
1531 <td>0</td>
1532 </tr>
1533 <tr>
1534 <td>0</td>
1535 <td>1</td>
1536 <td>1</td>
1537 </tr>
1538 <tr>
1539 <td>1</td>
1540 <td>0</td>
1541 <td>1</td>
1542 </tr>
1543 <tr>
1544 <td>1</td>
1545 <td>1</td>
1546 <td>0</td>
1547 </tr>
1548 </tbody>
1549</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1550</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1551<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1552<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1553<pre> &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1554 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1555 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1556 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1557</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1558</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1559<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1560<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1561Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1562<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1563<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1564<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1565</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1566<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1567<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1568the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1569<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1570<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1571 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1572type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1573<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1574<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1575<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1576<pre> &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 &lt;&lt; %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1577 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1578 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1579</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1580</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1581<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1582<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1583Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1584<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1585<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1586<pre> &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1587</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1588<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1589<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1590the right a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1591<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1592<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1593 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1594type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1595<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1596<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1597most significant bit is duplicated in the newly free'd bit positions.
1598If the first argument is unsigned, zero bits shall fill the empty
1599positions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1600<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1601<pre> &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 &gt;&gt; %var</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1602 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1603 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1604 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1605 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1606</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1607</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1608<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1609<div class="doc_subsection"> <a name="memoryops">Memory Access
1610Operations</a></div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1611<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1612<p>A key design point of an SSA-based representation is how it
1613represents memory. In LLVM, no memory locations are in SSA form, which
1614makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1615allocate, and free memory in LLVM.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1616</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1617<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1618<div class="doc_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>'
1619Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1620<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1621<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1622<pre> &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1623 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1624</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1625<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1626<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1627heap and returns a pointer to it.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1628<h5>Arguments:</h5>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]1629<p>The '<tt>malloc</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1630bytes of memory from the operating system and returns a pointer of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1631appropriate type to the program. The second form of the instruction is
1632a shorter version of the first instruction that defaults to allocating
1633one element.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1634<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1635<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1636<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1637a pointer is returned.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1638<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1639<pre> %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1640
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1641 %size = <a
1642 href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1643 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1644 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1645</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1646</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1647<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1648<div class="doc_subsubsection"> <a name="i_free">'<tt>free</tt>'
1649Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1650<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1651<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1652<pre> free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1653</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1654<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1655<p>The '<tt>free</tt>' instruction returns memory back to the unused
1656memory heap, to be reallocated in the future.</p>
1657<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1658<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1659<p>'<tt>value</tt>' shall be a pointer value that points to a value
1660that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1661instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1662<h5>Semantics:</h5>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1663<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1664after this instruction executes.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1665<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1666<pre> %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1667 free [4 x ubyte]* %array
1668</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1669</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1670<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1671<div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>'
1672Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1673<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1674<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1675<pre> &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1676 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1677</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1678<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1679<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1680stack frame of the procedure that is live until the current function
1681returns to its caller.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1682<h5>Arguments:</h5>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1683<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1684bytes of memory on the runtime stack, returning a pointer of the
1685appropriate type to the program. The second form of the instruction is
1686a shorter version of the first that defaults to allocating one element.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1687<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1688<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1689<p>Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d
1690memory is automatically released when the function returns. The '<tt>alloca</tt>'
1691instruction is commonly used to represent automatic variables that must
1692have an address available. When the function returns (either with the <tt><a
1693 href="#i_ret">ret</a></tt> or <tt><a href="#i_invoke">invoke</a></tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1694instructions), the memory is reclaimed.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1695<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1696<pre> %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1697 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1698</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1699</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1700<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1701<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1702Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1703<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1704<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1705<pre> &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;<br> &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;<br></pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1706<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1707<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1708<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1709<p>The argument to the '<tt>load</tt>' instruction specifies the memory
1710address to load from. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]1711 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1712marked as <tt>volatile</tt> then the optimizer is not allowed to modify
1713the number or order of execution of this <tt>load</tt> with other
1714volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1715instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1716<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1717<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1718<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1719<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1720 <a
1721 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1722 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1723</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1724</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1725<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1726<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1727Instruction</a> </div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1728<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1729<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattnerf0651072003-09-08 18:27:49 +0000[diff] [blame]1730 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1731</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1732<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1733<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1734<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1735<p>There are two arguments to the '<tt>store</tt>' instruction: a value
1736to store and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1737operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
1738operand. If the <tt>store</tt> is marked as <tt>volatile</tt> then the
1739optimizer is not allowed to modify the number or order of execution of
1740this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1741 href="#i_store">store</a></tt> instructions.</p>
1742<h5>Semantics:</h5>
1743<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1744at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1745<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1746<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1747 <a
1748 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1749 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1750</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1751<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1752<div class="doc_subsubsection">
1753 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
1754</div>
1755
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1756<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1757<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1758<pre>
1759 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
1760</pre>
1761
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1762<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1763
1764<p>
1765The '<tt>getelementptr</tt>' instruction is used to get the address of a
1766subelement of an aggregate data structure.</p>
1767
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1768<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1769
1770<p>This instruction takes a list of integer constants that indicate what
1771elements of the aggregate object to index to. The actual types of the arguments
1772provided depend on the type of the first pointer argument. The
1773'<tt>getelementptr</tt>' instruction is used to index down through the type
1774levels of a structure. When indexing into a structure, only <tt>uint</tt>
1775integer constants are allowed. When indexing into an array or pointer
1776<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
1777
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1778<p>For example, let's consider a C code fragment and how it gets
1779compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1780
1781<pre>
1782 struct RT {
1783 char A;
1784 int B[10][20];
1785 char C;
1786 };
1787 struct ST {
1788 int X;
1789 double Y;
1790 struct RT Z;
1791 };
1792
1793 int *foo(struct ST *s) {
1794 return &amp;s[1].Z.B[5][13];
1795 }
1796</pre>
1797
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1798<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1799
1800<pre>
1801 %RT = type { sbyte, [10 x [20 x int]], sbyte }
1802 %ST = type { int, double, %RT }
1803
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]1804 implementation
1805
1806 int* %foo(%ST* %s) {
1807 entry:
1808 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1809 ret int* %reg
1810 }
1811</pre>
1812
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1813<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1814
1815<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]1816on the pointer type that is being index into. <a href="#t_pointer">Pointer</a>
1817and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
1818<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1819types require <tt>uint</tt> <b>constants</b>.</p>
1820
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1821<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1822type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
1823}</tt>' type, a structure. The second index indexes into the third element of
1824the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
1825sbyte }</tt>' type, another structure. The third index indexes into the second
1826element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
1827array. The two dimensions of the array are subscripted into, yielding an
1828'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction return a pointer
1829to this element, thus computing a value of '<tt>int*</tt>' type.</p>
1830
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1831<p>Note that it is perfectly legal to index partially through a
1832structure, returning a pointer to an inner element. Because of this,
1833the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1834
1835<pre>
1836 int* "foo"(%ST* %s) {
1837 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
1838 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
1839 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1840 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
1841 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
1842 ret int* %t5
1843 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1844</pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1845<h5>Example:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1846<pre>
1847 <i>; yields [12 x ubyte]*:aptr</i>
1848 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
1849</pre>
1850
1851</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1852<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1853<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1854<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1855<p>The instructions in this category are the "miscellaneous"
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1856instructions, which defy better classification.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1857</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1858<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1859<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
1860Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1861<div class="doc_text">
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1862<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1863<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1864<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1865<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
1866the SSA graph representing the function.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1867<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1868<p>The type of the incoming values are specified with the first type
1869field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
1870as arguments, with one pair for each predecessor basic block of the
1871current block. Only values of <a href="#t_firstclass">first class</a>
1872type may be used as the value arguments to the PHI node. Only labels
1873may be used as the label arguments.</p>
1874<p>There must be no non-phi instructions between the start of a basic
1875block and the PHI instructions: i.e. PHI instructions must be first in
1876a basic block.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1877<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1878<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
1879value specified by the parameter, depending on which basic block we
1880came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1881<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1882<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1883</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1884
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1885<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1886<div class="doc_subsubsection">
1887 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
1888</div>
1889
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1890<div class="doc_text">
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1891
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1892<h5>Syntax:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1893
1894<pre>
1895 &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1896</pre>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1897
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1898<h5>Overview:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1899
1900<p>
1901The '<tt>cast</tt>' instruction is used as the primitive means to convert
1902integers to floating point, change data type sizes, and break type safety (by
1903casting pointers).
1904</p>
1905
1906
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1907<h5>Arguments:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1908
1909<p>
1910The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
1911class value, and a type to cast it to, which must also be a <a
1912href="#t_firstclass">first class</a> type.
1913</p>
1914
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1915<h5>Semantics:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1916
1917<p>
1918This instruction follows the C rules for explicit casts when determining how the
1919data being cast must change to fit in its new container.
1920</p>
1921
1922<p>
1923When casting to bool, any value that would be considered true in the context of
1924a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
1925all else are '<tt>false</tt>'.
1926</p>
1927
1928<p>
1929When extending an integral value from a type of one signness to another (for
1930example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
1931<b>source</b> value is signed, and zero-extended if the source value is
1932unsigned. <tt>bool</tt> values are always zero extended into either zero or
1933one.
1934</p>
1935
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1936<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1937
1938<pre>
1939 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1940 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1941</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1942</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]1943
1944<!-- _______________________________________________________________________ -->
1945<div class="doc_subsubsection">
1946 <a name="i_select">'<tt>select</tt>' Instruction</a>
1947</div>
1948
1949<div class="doc_text">
1950
1951<h5>Syntax:</h5>
1952
1953<pre>
1954 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
1955</pre>
1956
1957<h5>Overview:</h5>
1958
1959<p>
1960The '<tt>select</tt>' instruction is used to choose one value based on a
1961condition, without branching.
1962</p>
1963
1964
1965<h5>Arguments:</h5>
1966
1967<p>
1968The '<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.
1969</p>
1970
1971<h5>Semantics:</h5>
1972
1973<p>
1974If the boolean condition evaluates to true, the instruction returns the first
1975value argument, otherwise it returns the second value argument.
1976</p>
1977
1978<h5>Example:</h5>
1979
1980<pre>
1981 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
1982</pre>
1983</div>
1984
1985
1986
1987
1988
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1989<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1990<div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>'
1991Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1992<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1993<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1994<pre> &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1995<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1996<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1997<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1998<p>This instruction requires several arguments:</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1999<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2000 <li>
2001 <p>'<tt>ty</tt>': shall be the signature of the pointer to function
2002value being invoked. The argument types must match the types implied
2003by this signature.</p>
2004 </li>
2005 <li>
2006 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a
2007function to be invoked. In most cases, this is a direct function
2008invocation, but indirect <tt>call</tt>s are just as possible,
2009calling an arbitrary pointer to function values.</p>
2010 </li>
2011 <li>
2012 <p>'<tt>function args</tt>': argument list whose types match the
2013function signature argument types. If the function signature
2014indicates the function accepts a variable number of arguments, the
2015extra arguments can be specified.</p>
2016 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2017</ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2018<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2019<p>The '<tt>call</tt>' instruction is used to cause control flow to
2020transfer to a specified function, with its incoming arguments bound to
2021the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2022instruction in the called function, control flow continues with the
2023instruction after the function call, and the return value of the
2024function is bound to the result argument. This is a simpler case of
2025the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2026<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2027<pre> %retval = call int %test(int %argc)<br> call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2028</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2029
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2030<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2031<div class="doc_subsubsection">
2032 <a name="i_vanext">'<tt>vanext</tt>' Instruction</a>
2033</div>
2034
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2035<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2036
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2037<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2038
2039<pre>
2040 &lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
2041</pre>
2042
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2043<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2044
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2045<p>The '<tt>vanext</tt>' instruction is used to access arguments passed
2046through the "variable argument" area of a function call. It is used to
2047implement the <tt>va_arg</tt> macro in C.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2048
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2049<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2050
2051<p>This instruction takes a <tt>va_list</tt> value and the type of the
2052argument. It returns another <tt>va_list</tt>. The actual type of
2053<tt>va_list</tt> may be defined differently for different targets. Most targets
2054use a <tt>va_list</tt> type of <tt>sbyte*</tt> or some other pointer type.</p>
2055
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2056<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2057
2058<p>The '<tt>vanext</tt>' instruction advances the specified <tt>va_list</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2059past an argument of the specified type. In conjunction with the <a
2060 href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement
2061the <tt>va_arg</tt> macro available in C. For more information, see
2062the variable argument handling <a href="#int_varargs">Intrinsic
2063Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2064
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2065<p>It is legal for this instruction to be called in a function which
2066does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2067function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2068
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2069<p><tt>vanext</tt> is an LLVM instruction instead of an <a
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2070href="#intrinsics">intrinsic function</a> because it takes a type as an
2071argument. The type refers to the current argument in the <tt>va_list</tt>, it
2072tells the compiler how far on the stack it needs to advance to find the next
2073argument</p>
2074
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2075<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2076
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2077<p>See the <a href="#int_varargs">variable argument processing</a>
2078section.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2079
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2080</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2081
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2082<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2083<div class="doc_subsubsection">
2084 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
2085</div>
2086
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2087<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2088
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2089<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2090
2091<pre>
2092 &lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
2093</pre>
2094
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2095<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2096
2097<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed through
2098the "variable argument" area of a function call. It is used to implement the
2099<tt>va_arg</tt> macro in C.</p>
2100
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2101<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2102
2103<p>This instruction takes a <tt>va_list</tt> value and the type of the
2104argument. It returns a value of the specified argument type. Again, the actual
2105type of <tt>va_list</tt> is target specific.</p>
2106
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2107<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2108
2109<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified type from
2110the specified <tt>va_list</tt>. In conjunction with the <a
2111href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to implement the
2112<tt>va_arg</tt> macro available in C. For more information, see the variable
2113argument handling <a href="#int_varargs">Intrinsic Functions</a>.</p>
2114
2115<p>It is legal for this instruction to be called in a function which does not
2116take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2117function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2118
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2119<p><tt>vaarg</tt> is an LLVM instruction instead of an <a
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2120href="#intrinsics">intrinsic function</a> because it takes an type as an
2121argument.</p>
2122
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2123<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2124
2125<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2126
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2127</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2128
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2129<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2130<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2131<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2132
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2133<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2134
2135<p>LLVM supports the notion of an "intrinsic function". These functions have
2136well known names and semantics, and are required to follow certain
2137restrictions. Overall, these instructions represent an extension mechanism for
2138the LLVM language that does not require changing all of the transformations in
2139LLVM to add to the language (or the bytecode reader/writer, the parser,
2140etc...).</p>
2141
2142<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix, this
2143prefix is reserved in LLVM for intrinsic names, thus functions may not be named
2144this. Intrinsic functions must always be external functions: you cannot define
2145the body of intrinsic functions. Intrinsic functions may only be used in call
2146or invoke instructions: it is illegal to take the address of an intrinsic
2147function. Additionally, because intrinsic functions are part of the LLVM
2148language, it is required that they all be documented here if any are added.</p>
2149
2150
2151<p>
2152Adding an intrinsic to LLVM is straight-forward if it is possible to express the
2153concept in LLVM directly (ie, code generator support is not _required_). To do
2154this, extend the default implementation of the IntrinsicLowering class to handle
2155the intrinsic. Code generators use this class to lower intrinsics they do not
2156understand to raw LLVM instructions that they do.
2157</p>
2158
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2159</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2160
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2161<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2162<div class="doc_subsection">
2163 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2164</div>
2165
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2166<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2167
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2168<p>Variable argument support is defined in LLVM with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2169 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
2170intrinsic functions. These functions are related to the similarly
2171named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2172
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2173<p>All of these functions operate on arguments that use a
2174target-specific value type "<tt>va_list</tt>". The LLVM assembly
2175language reference manual does not define what this type is, so all
2176transformations should be prepared to handle intrinsics with any type
2177used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2178
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2179<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2180instruction and the variable argument handling intrinsic functions are
2181used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2182
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2183<pre>
2184int %test(int %X, ...) {
2185 ; Initialize variable argument processing
2186 %ap = call sbyte* %<a href="#i_va_start">llvm.va_start</a>()
2187
2188 ; Read a single integer argument
2189 %tmp = vaarg sbyte* %ap, int
2190
2191 ; Advance to the next argument
2192 %ap2 = vanext sbyte* %ap, int
2193
2194 ; Demonstrate usage of llvm.va_copy and llvm.va_end
2195 %aq = call sbyte* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)
2196 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq)
2197
2198 ; Stop processing of arguments.
2199 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)
2200 ret int %tmp
2201}
2202</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2203</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2204
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2205<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2206<div class="doc_subsubsection">
2207 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2208</div>
2209
2210
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2211<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2212<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2213<pre> call &lt;va_list&gt; ()* %llvm.va_start()<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2214<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2215<p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
2216for subsequent use by the variable argument intrinsics.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2217<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2218<p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2219macro available in C. In a target-dependent way, it initializes and
2220returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt>
2221will produce the first variable argument passed to the function. Unlike
2222the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2223last argument of the function, the compiler can figure that out.</p>
2224<p>Note that this intrinsic function is only legal to be called from
2225within the body of a variable argument function.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2226</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2227
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2228<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2229<div class="doc_subsubsection">
2230 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2231</div>
2232
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2233<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2234<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2235<pre> call void (&lt;va_list&gt;)* %llvm.va_end(&lt;va_list&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2236<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2237<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2238which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2239or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2240<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2241<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2242<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2243<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2244macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2245Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2246 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2247with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2248</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2249
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2250<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2251<div class="doc_subsubsection">
2252 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2253</div>
2254
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2255<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2256
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2257<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2258
2259<pre>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2260 call &lt;va_list&gt; (&lt;va_list&gt;)* %llvm.va_copy(&lt;va_list&gt; &lt;destarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2261</pre>
2262
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2263<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2264
2265<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
2266from the source argument list to the destination argument list.</p>
2267
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2268<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2269
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2270<p>The argument is the <tt>va_list</tt> to copy.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2271
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2272<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2273
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2274<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2275macro available in C. In a target-dependent way, it copies the source
2276<tt>va_list</tt> element into the returned list. This intrinsic is necessary
Chris Lattnerfcd37252004-06-21 22:52:48 +0000[diff] [blame]2277because the <tt><a href="#i_va_start">llvm.va_start</a></tt> intrinsic may be
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2278arbitrarily complex and require memory allocation, for example.</p>
2279
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2280</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2281
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2282<!-- ======================================================================= -->
2283<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2284 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2285</div>
2286
2287<div class="doc_text">
2288
2289<p>
2290LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2291Collection</a> requires the implementation and generation of these intrinsics.
2292These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2293stack</a>, as well as garbage collector implementations that require <a
2294href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2295Front-ends for type-safe garbage collected languages should generate these
2296intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2297href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2298</p>
2299</div>
2300
2301<!-- _______________________________________________________________________ -->
2302<div class="doc_subsubsection">
2303 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2304</div>
2305
2306<div class="doc_text">
2307
2308<h5>Syntax:</h5>
2309
2310<pre>
2311 call void (&lt;ty&gt;**, &lt;ty2&gt;*)* %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
2312</pre>
2313
2314<h5>Overview:</h5>
2315
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2316<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2317the code generator, and allows some metadata to be associated with it.</p>
2318
2319<h5>Arguments:</h5>
2320
2321<p>The first argument specifies the address of a stack object that contains the
2322root pointer. The second pointer (which must be either a constant or a global
2323value address) contains the meta-data to be associated with the root.</p>
2324
2325<h5>Semantics:</h5>
2326
2327<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2328location. At compile-time, the code generator generates information to allow
2329the runtime to find the pointer at GC safe points.
2330</p>
2331
2332</div>
2333
2334
2335<!-- _______________________________________________________________________ -->
2336<div class="doc_subsubsection">
2337 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2338</div>
2339
2340<div class="doc_text">
2341
2342<h5>Syntax:</h5>
2343
2344<pre>
2345 call sbyte* (sbyte**)* %llvm.gcread(sbyte** %Ptr)
2346</pre>
2347
2348<h5>Overview:</h5>
2349
2350<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2351locations, allowing garbage collector implementations that require read
2352barriers.</p>
2353
2354<h5>Arguments:</h5>
2355
2356<p>The argument is the address to read from, which should be an address
2357allocated from the garbage collector.</p>
2358
2359<h5>Semantics:</h5>
2360
2361<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2362instruction, but may be replaced with substantially more complex code by the
2363garbage collector runtime, as needed.</p>
2364
2365</div>
2366
2367
2368<!-- _______________________________________________________________________ -->
2369<div class="doc_subsubsection">
2370 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2371</div>
2372
2373<div class="doc_text">
2374
2375<h5>Syntax:</h5>
2376
2377<pre>
2378 call void (sbyte*, sbyte**)* %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
2379</pre>
2380
2381<h5>Overview:</h5>
2382
2383<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2384locations, allowing garbage collector implementations that require write
2385barriers (such as generational or reference counting collectors).</p>
2386
2387<h5>Arguments:</h5>
2388
2389<p>The first argument is the reference to store, and the second is the heap
2390location to store to.</p>
2391
2392<h5>Semantics:</h5>
2393
2394<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2395instruction, but may be replaced with substantially more complex code by the
2396garbage collector runtime, as needed.</p>
2397
2398</div>
2399
2400
2401
2402<!-- ======================================================================= -->
2403<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2404 <a name="int_codegen">Code Generator Intrinsics</a>
2405</div>
2406
2407<div class="doc_text">
2408<p>
2409These intrinsics are provided by LLVM to expose special features that may only
2410be implemented with code generator support.
2411</p>
2412
2413</div>
2414
2415<!-- _______________________________________________________________________ -->
2416<div class="doc_subsubsection">
2417 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2418</div>
2419
2420<div class="doc_text">
2421
2422<h5>Syntax:</h5>
2423<pre>
2424 call void* ()* %llvm.returnaddress(uint &lt;level&gt;)
2425</pre>
2426
2427<h5>Overview:</h5>
2428
2429<p>
2430The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2431indicating the return address of the current function or one of its callers.
2432</p>
2433
2434<h5>Arguments:</h5>
2435
2436<p>
2437The argument to this intrinsic indicates which function to return the address
2438for. Zero indicates the calling function, one indicates its caller, etc. The
2439argument is <b>required</b> to be a constant integer value.
2440</p>
2441
2442<h5>Semantics:</h5>
2443
2444<p>
2445The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2446the return address of the specified call frame, or zero if it cannot be
2447identified. The value returned by this intrinsic is likely to be incorrect or 0
2448for arguments other than zero, so it should only be used for debugging purposes.
2449</p>
2450
2451<p>
2452Note that calling this intrinsic does not prevent function inlining or other
2453aggressive transformations, so the value returned may not that of the obvious
2454source-language caller.
2455</p>
2456</div>
2457
2458
2459<!-- _______________________________________________________________________ -->
2460<div class="doc_subsubsection">
2461 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2462</div>
2463
2464<div class="doc_text">
2465
2466<h5>Syntax:</h5>
2467<pre>
2468 call void* ()* %llvm.frameaddress(uint &lt;level&gt;)
2469</pre>
2470
2471<h5>Overview:</h5>
2472
2473<p>
2474The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2475pointer value for the specified stack frame.
2476</p>
2477
2478<h5>Arguments:</h5>
2479
2480<p>
2481The argument to this intrinsic indicates which function to return the frame
2482pointer for. Zero indicates the calling function, one indicates its caller,
2483etc. The argument is <b>required</b> to be a constant integer value.
2484</p>
2485
2486<h5>Semantics:</h5>
2487
2488<p>
2489The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2490the frame address of the specified call frame, or zero if it cannot be
2491identified. The value returned by this intrinsic is likely to be incorrect or 0
2492for arguments other than zero, so it should only be used for debugging purposes.
2493</p>
2494
2495<p>
2496Note that calling this intrinsic does not prevent function inlining or other
2497aggressive transformations, so the value returned may not that of the obvious
2498source-language caller.
2499</p>
2500</div>
2501
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2502<!-- ======================================================================= -->
2503<div class="doc_subsection">
2504 <a name="int_os">Operating System Intrinsics</a>
2505</div>
2506
2507<div class="doc_text">
2508<p>
2509These intrinsics are provided by LLVM to support the implementation of
2510operating system level code.
2511</p>
2512
2513</div>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2514
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2515<!-- _______________________________________________________________________ -->
2516<div class="doc_subsubsection">
2517 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2518</div>
2519
2520<div class="doc_text">
2521
2522<h5>Syntax:</h5>
2523<pre>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2524 call &lt;integer type&gt; (&lt;integer type&gt;)* %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2525</pre>
2526
2527<h5>Overview:</h5>
2528
2529<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2530The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2531I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2532</p>
2533
2534<h5>Arguments:</h5>
2535
2536<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2537The argument to this intrinsic indicates the hardware I/O address from which
2538to read the data. The address is in the hardware I/O address namespace (as
2539opposed to being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2540</p>
2541
2542<h5>Semantics:</h5>
2543
2544<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2545The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2546specified by <i>address</i> and returns the value. The address and return
2547value must be integers, but the size is dependent upon the platform upon which
2548the program is code generated. For example, on x86, the address must be an
2549unsigned 16 bit value, and the return value must be 8, 16, or 32 bits.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2550</p>
2551
2552</div>
2553
2554<!-- _______________________________________________________________________ -->
2555<div class="doc_subsubsection">
2556 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2557</div>
2558
2559<div class="doc_text">
2560
2561<h5>Syntax:</h5>
2562<pre>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]2563 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
2564 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
2565 &lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2566</pre>
2567
2568<h5>Overview:</h5>
2569
2570<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2571The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2572I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2573</p>
2574
2575<h5>Arguments:</h5>
2576
2577<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2578The first argument is the value to write to the I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2579</p>
2580
2581<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2582The second argument indicates the hardware I/O address to which data should be
2583written. The address is in the hardware I/O address namespace (as opposed to
2584being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2585</p>
2586
2587<h5>Semantics:</h5>
2588
2589<p>
2590The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2591specified by <i>address</i>. The address and value must be integers, but the
2592size is dependent upon the platform upon which the program is code generated.
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2593For example, on x86, the address must be an unsigned 16 bit value, and the
2594value written must be 8, 16, or 32 bits in length.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2595</p>
2596
2597</div>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2598
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2599<!-- _______________________________________________________________________ -->
2600<div class="doc_subsubsection">
2601 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
2602</div>
2603
2604<div class="doc_text">
2605
2606<h5>Syntax:</h5>
2607<pre>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2608 call &lt;result&gt; (&lt;ty&gt;*)* %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2609</pre>
2610
2611<h5>Overview:</h5>
2612
2613<p>
2614The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
2615address.
2616</p>
2617
2618<h5>Arguments:</h5>
2619
2620<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2621The argument to this intrinsic is a pointer indicating the memory address from
2622which to read the data. The data must be a
2623<a href="#t_firstclass">first class</a> type.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2624</p>
2625
2626<h5>Semantics:</h5>
2627
2628<p>
2629The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2630location specified by <i>pointer</i> and returns the value. The argument must
2631be a pointer, and the return value must be a
2632<a href="#t_firstclass">first class</a> type. However, certain architectures
2633may not support I/O on all first class types. For example, 32 bit processors
2634may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2635</p>
2636
2637<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2638This intrinsic enforces an in-order memory model for llvm.readio and
2639llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2640scheduled processors may execute loads and stores out of order, re-ordering at
2641run time accesses to memory mapped I/O registers. Using these intrinsics
2642ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2643</p>
2644
2645</div>
2646
2647<!-- _______________________________________________________________________ -->
2648<div class="doc_subsubsection">
2649 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
2650</div>
2651
2652<div class="doc_text">
2653
2654<h5>Syntax:</h5>
2655<pre>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2656 call void (&lt;ty1&gt;, &lt;ty2&gt;*)* %llvm.writeio (&lt;ty1&gt; &lt;value&gt;, &lt;ty2&gt; * &lt;pointer&gt;)
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2657</pre>
2658
2659<h5>Overview:</h5>
2660
2661<p>
2662The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
2663mapped I/O address.
2664</p>
2665
2666<h5>Arguments:</h5>
2667
2668<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2669The first argument is the value to write to the memory mapped I/O location.
2670The second argument is a pointer indicating the memory address to which the
2671data should be written.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2672</p>
2673
2674<h5>Semantics:</h5>
2675
2676<p>
2677The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2678I/O address specified by <i>pointer</i>. The value must be a
2679<a href="#t_firstclass">first class</a> type. However, certain architectures
2680may not support I/O on all first class types. For example, 32 bit processors
2681may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2682</p>
2683
2684<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2685This intrinsic enforces an in-order memory model for llvm.readio and
2686llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2687scheduled processors may execute loads and stores out of order, re-ordering at
2688run time accesses to memory mapped I/O registers. Using these intrinsics
2689ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2690</p>
2691
2692</div>
2693
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2694<!-- ======================================================================= -->
2695<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2696 <a name="int_libc">Standard C Library Intrinsics</a>
2697</div>
2698
2699<div class="doc_text">
2700<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2701LLVM provides intrinsics for a few important standard C library functions.
2702These intrinsics allow source-language front-ends to pass information about the
2703alignment of the pointer arguments to the code generator, providing opportunity
2704for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2705</p>
2706
2707</div>
2708
2709<!-- _______________________________________________________________________ -->
2710<div class="doc_subsubsection">
2711 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
2712</div>
2713
2714<div class="doc_text">
2715
2716<h5>Syntax:</h5>
2717<pre>
2718 call void (sbyte*, sbyte*, uint, uint)* %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
2719 uint &lt;len&gt;, uint &lt;align&gt;)
2720</pre>
2721
2722<h5>Overview:</h5>
2723
2724<p>
2725The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
2726location to the destination location.
2727</p>
2728
2729<p>
2730Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
2731does not return a value, and takes an extra alignment argument.
2732</p>
2733
2734<h5>Arguments:</h5>
2735
2736<p>
2737The first argument is a pointer to the destination, the second is a pointer to
2738the source. The third argument is an (arbitrarily sized) integer argument
2739specifying the number of bytes to copy, and the fourth argument is the alignment
2740of the source and destination locations.
2741</p>
2742
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]2743<p>
2744If the call to this intrinisic has an alignment value that is not 0 or 1, then
2745the caller guarantees that the size of the copy is a multiple of the alignment
2746and that both the source and destination pointers are aligned to that boundary.
2747</p>
2748
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2749<h5>Semantics:</h5>
2750
2751<p>
2752The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
2753location to the destination location, which are not allowed to overlap. It
2754copies "len" bytes of memory over. If the argument is known to be aligned to
2755some boundary, this can be specified as the fourth argument, otherwise it should
2756be set to 0 or 1.
2757</p>
2758</div>
2759
2760
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]2761<!-- _______________________________________________________________________ -->
2762<div class="doc_subsubsection">
2763 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
2764</div>
2765
2766<div class="doc_text">
2767
2768<h5>Syntax:</h5>
2769<pre>
2770 call void (sbyte*, sbyte*, uint, uint)* %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
2771 uint &lt;len&gt;, uint &lt;align&gt;)
2772</pre>
2773
2774<h5>Overview:</h5>
2775
2776<p>
2777The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
2778location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
2779intrinsic but allows the two memory locations to overlap.
2780</p>
2781
2782<p>
2783Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
2784does not return a value, and takes an extra alignment argument.
2785</p>
2786
2787<h5>Arguments:</h5>
2788
2789<p>
2790The first argument is a pointer to the destination, the second is a pointer to
2791the source. The third argument is an (arbitrarily sized) integer argument
2792specifying the number of bytes to copy, and the fourth argument is the alignment
2793of the source and destination locations.
2794</p>
2795
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]2796<p>
2797If the call to this intrinisic has an alignment value that is not 0 or 1, then
2798the caller guarantees that the size of the copy is a multiple of the alignment
2799and that both the source and destination pointers are aligned to that boundary.
2800</p>
2801
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]2802<h5>Semantics:</h5>
2803
2804<p>
2805The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
2806location to the destination location, which may overlap. It
2807copies "len" bytes of memory over. If the argument is known to be aligned to
2808some boundary, this can be specified as the fourth argument, otherwise it should
2809be set to 0 or 1.
2810</p>
2811</div>
2812
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2813
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2814<!-- _______________________________________________________________________ -->
2815<div class="doc_subsubsection">
2816 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
2817</div>
2818
2819<div class="doc_text">
2820
2821<h5>Syntax:</h5>
2822<pre>
2823 call void (sbyte*, ubyte, uint, uint)* %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
2824 uint &lt;len&gt;, uint &lt;align&gt;)
2825</pre>
2826
2827<h5>Overview:</h5>
2828
2829<p>
2830The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
2831byte value.
2832</p>
2833
2834<p>
2835Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
2836does not return a value, and takes an extra alignment argument.
2837</p>
2838
2839<h5>Arguments:</h5>
2840
2841<p>
2842The first argument is a pointer to the destination to fill, the second is the
2843byte value to fill it with, the third argument is an (arbitrarily sized) integer
2844argument specifying the number of bytes to fill, and the fourth argument is the
2845known alignment of destination location.
2846</p>
2847
2848<p>
2849If the call to this intrinisic has an alignment value that is not 0 or 1, then
2850the caller guarantees that the size of the copy is a multiple of the alignment
2851and that the destination pointer is aligned to that boundary.
2852</p>
2853
2854<h5>Semantics:</h5>
2855
2856<p>
2857The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
2858destination location. If the argument is known to be aligned to some boundary,
2859this can be specified as the fourth argument, otherwise it should be set to 0 or
28601.
2861</p>
2862</div>
2863
2864
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]2865<!-- _______________________________________________________________________ -->
2866<div class="doc_subsubsection">
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]2867 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
2868</div>
2869
2870<div class="doc_text">
2871
2872<h5>Syntax:</h5>
2873<pre>
2874 call bool (&lt;float or double&gt;, &lt;float or double&gt;)* %llvm.isunordered(&lt;float or double&gt; Val1,
2875 &lt;float or double&gt; Val2)
2876</pre>
2877
2878<h5>Overview:</h5>
2879
2880<p>
2881The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
2882specified floating point values is a NAN.
2883</p>
2884
2885<h5>Arguments:</h5>
2886
2887<p>
2888The arguments are floating point numbers of the same type.
2889</p>
2890
2891<h5>Semantics:</h5>
2892
2893<p>
2894If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
2895false.
2896</p>
2897</div>
2898
2899
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]2900
2901
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2902<!-- ======================================================================= -->
2903<div class="doc_subsection">
2904 <a name="int_debugger">Debugger Intrinsics</a>
2905</div>
2906
2907<div class="doc_text">
2908<p>
2909The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
2910are described in the <a
2911href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
2912Debugging</a> document.
2913</p>
2914</div>
2915
2916
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2917<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2918<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2919<address>
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2924
2925 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
2926 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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