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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 88f6c46cb910b557e77714330a2e64f528aa53c3 / . / docs / LangRef.html
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4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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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 Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]25 <li><a href="#globalvars">Global Variables</a></li>
26 <li><a href="#functionstructure">Function Structure</a></li>
27 </ol>
28 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]29 <li><a href="#typesystem">Type System</a>
30 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]31 <li><a href="#t_primitive">Primitive Types</a>
32 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]33 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]34 </ol>
35 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]36 <li><a href="#t_derived">Derived Types</a>
37 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]38 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]39 <li><a href="#t_function">Function Type</a></li>
40 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]41 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]42 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]43 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]44 </ol>
45 </li>
46 </ol>
47 </li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]48 <li><a href="#constants">Constants</a>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]49 <ol>
50 <li><a href="#simpleconstants">Simple Constants</a>
51 <li><a href="#aggregateconstants">Aggregate Constants</a>
52 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
53 <li><a href="#undefvalues">Undefined Values</a>
54 <li><a href="#constantexprs">Constant Expressions</a>
55 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]56 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]57 <li><a href="#instref">Instruction Reference</a>
58 <ol>
59 <li><a href="#terminators">Terminator Instructions</a>
60 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]61 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
62 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]63 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
64 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]65 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]66 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]67 </ol>
68 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]69 <li><a href="#binaryops">Binary Operations</a>
70 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]71 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
72 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
73 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
74 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
75 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]76 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]77 </ol>
78 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]79 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
80 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]81 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]82 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]83 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
84 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
85 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]86 </ol>
87 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]88 <li><a href="#memoryops">Memory Access Operations</a>
89 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]90 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
91 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
92 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
93 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
94 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
95 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
96 </ol>
97 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]98 <li><a href="#otherops">Other Operations</a>
99 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]100 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]101 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]102 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]103 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]104 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]105 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]106 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]107 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]108 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]109 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]110 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]111 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
112 <ol>
113 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
114 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
115 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
116 </ol>
117 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]118 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
119 <ol>
120 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
121 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
122 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
123 </ol>
124 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]125 <li><a href="#int_codegen">Code Generator Intrinsics</a>
126 <ol>
127 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
128 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]129 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]130 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]131 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]132 </ol>
133 </li>
134 <li><a href="#int_os">Operating System Intrinsics</a>
135 <ol>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]136 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
137 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]138 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
139 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]140 </ol>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]141 <li><a href="#int_libc">Standard C Library Intrinsics</a>
142 <ol>
143 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]144 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]145 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos96853722004-06-12 19:19:14 +0000[diff] [blame]146 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]147 <li><a href="#i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a></li>
148
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]149 </ol>
150 </li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]151 <li><a href="#int_count">Bit counting Intrinsics</a>
152 <ol>
153 <li><a href="#int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]154 <li><a href="#int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic </a></li>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]155 <li><a href="#int_cttz">'<tt>llvm.cttz</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]156 </ol>
157 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]158 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]159 </ol>
160 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]161</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]162
163<div class="doc_author">
164 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
165 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></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="abstract">Abstract </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 Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]173<p>This document is a reference manual for the LLVM assembly language.
174LLVM is an SSA based representation that provides type safety,
175low-level operations, flexibility, and the capability of representing
176'all' high-level languages cleanly. It is the common code
177representation used throughout all phases of the LLVM compilation
178strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]179</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]180
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]181<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]182<div class="doc_section"> <a name="introduction">Introduction</a> </div>
183<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]184
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]185<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]186
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]187<p>The LLVM code representation is designed to be used in three
188different forms: as an in-memory compiler IR, as an on-disk bytecode
189representation (suitable for fast loading by a Just-In-Time compiler),
190and as a human readable assembly language representation. This allows
191LLVM to provide a powerful intermediate representation for efficient
192compiler transformations and analysis, while providing a natural means
193to debug and visualize the transformations. The three different forms
194of LLVM are all equivalent. This document describes the human readable
195representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]196
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]197<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]198while being expressive, typed, and extensible at the same time. It
199aims to be a "universal IR" of sorts, by being at a low enough level
200that high-level ideas may be cleanly mapped to it (similar to how
201microprocessors are "universal IR's", allowing many source languages to
202be mapped to them). By providing type information, LLVM can be used as
203the target of optimizations: for example, through pointer analysis, it
204can be proven that a C automatic variable is never accessed outside of
205the current function... allowing it to be promoted to a simple SSA
206value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]207
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]208</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]209
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]210<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]211<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]212
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]213<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]214
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]215<p>It is important to note that this document describes 'well formed'
216LLVM assembly language. There is a difference between what the parser
217accepts and what is considered 'well formed'. For example, the
218following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]219
220<pre>
221 %x = <a href="#i_add">add</a> int 1, %x
222</pre>
223
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]224<p>...because the definition of <tt>%x</tt> does not dominate all of
225its uses. The LLVM infrastructure provides a verification pass that may
226be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]227automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]228the optimizer before it outputs bytecode. The violations pointed out
229by the verifier pass indicate bugs in transformation passes or input to
230the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]231
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]232<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]233
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]234<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]235<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]236<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]237
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]238<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]239
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]240<p>LLVM uses three different forms of identifiers, for different
241purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]242
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]243<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]244 <li>Named values are represented as a string of characters with a '%' prefix.
245 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
246 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
247 Identifiers which require other characters in their names can be surrounded
248 with quotes. In this way, anything except a <tt>"</tt> character can be used
249 in a name.</li>
250
251 <li>Unnamed values are represented as an unsigned numeric value with a '%'
252 prefix. For example, %12, %2, %44.</li>
253
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]254 <li>Constants, which are described in a <a href="#constants">section about
255 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]256</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]257
258<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
259don't need to worry about name clashes with reserved words, and the set of
260reserved words may be expanded in the future without penalty. Additionally,
261unnamed identifiers allow a compiler to quickly come up with a temporary
262variable without having to avoid symbol table conflicts.</p>
263
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]264<p>Reserved words in LLVM are very similar to reserved words in other
265languages. There are keywords for different opcodes ('<tt><a
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]266href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
267href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
268href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
269and others. These reserved words cannot conflict with variable names, because
270none of them start with a '%' character.</p>
271
272<p>Here is an example of LLVM code to multiply the integer variable
273'<tt>%X</tt>' by 8:</p>
274
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]275<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]276
277<pre>
278 %result = <a href="#i_mul">mul</a> uint %X, 8
279</pre>
280
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]281<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]282
283<pre>
284 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
285</pre>
286
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]287<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]288
289<pre>
290 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
291 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
292 %result = <a href="#i_add">add</a> uint %1, %1
293</pre>
294
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]295<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
296important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]297
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]298<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]299
300 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
301 line.</li>
302
303 <li>Unnamed temporaries are created when the result of a computation is not
304 assigned to a named value.</li>
305
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]306 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]307
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]308</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]309
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]310<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]311demonstrating instructions, we will follow an instruction with a comment that
312defines the type and name of value produced. Comments are shown in italic
313text.</p>
314
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]315</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]316
317<!-- *********************************************************************** -->
318<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
319<!-- *********************************************************************** -->
320
321<!-- ======================================================================= -->
322<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
323</div>
324
325<div class="doc_text">
326
327<p>LLVM programs are composed of "Module"s, each of which is a
328translation unit of the input programs. Each module consists of
329functions, global variables, and symbol table entries. Modules may be
330combined together with the LLVM linker, which merges function (and
331global variable) definitions, resolves forward declarations, and merges
332symbol table entries. Here is an example of the "hello world" module:</p>
333
334<pre><i>; Declare the string constant as a global constant...</i>
335<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
336 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
337
338<i>; External declaration of the puts function</i>
339<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
340
341<i>; Definition of main function</i>
342int %main() { <i>; int()* </i>
343 <i>; Convert [13x sbyte]* to sbyte *...</i>
344 %cast210 = <a
345 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
346
347 <i>; Call puts function to write out the string to stdout...</i>
348 <a
349 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
350 <a
351 href="#i_ret">ret</a> int 0<br>}<br></pre>
352
353<p>This example is made up of a <a href="#globalvars">global variable</a>
354named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
355function, and a <a href="#functionstructure">function definition</a>
356for "<tt>main</tt>".</p>
357
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]358<p>In general, a module is made up of a list of global values,
359where both functions and global variables are global values. Global values are
360represented by a pointer to a memory location (in this case, a pointer to an
361array of char, and a pointer to a function), and have one of the following <a
362href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]363
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]364</div>
365
366<!-- ======================================================================= -->
367<div class="doc_subsection">
368 <a name="linkage">Linkage Types</a>
369</div>
370
371<div class="doc_text">
372
373<p>
374All Global Variables and Functions have one of the following types of linkage:
375</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]376
377<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]378
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]379 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]380
381 <dd>Global values with internal linkage are only directly accessible by
382 objects in the current module. In particular, linking code into a module with
383 an internal global value may cause the internal to be renamed as necessary to
384 avoid collisions. Because the symbol is internal to the module, all
385 references can be updated. This corresponds to the notion of the
386 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]387 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]388
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]389 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]390
391 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
392 the twist that linking together two modules defining the same
393 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
394 is typically used to implement inline functions. Unreferenced
395 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]396 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]397
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]398 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]399
400 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
401 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
402 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]403 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]404
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]405 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]406
407 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
408 pointer to array type. When two global variables with appending linkage are
409 linked together, the two global arrays are appended together. This is the
410 LLVM, typesafe, equivalent of having the system linker append together
411 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]412 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]413
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]414 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]415
416 <dd>If none of the above identifiers are used, the global is externally
417 visible, meaning that it participates in linkage and can be used to resolve
418 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]419 </dd>
420</dl>
421
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]422<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
423variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
424variable and was linked with this one, one of the two would be renamed,
425preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
426external (i.e., lacking any linkage declarations), they are accessible
427outside of the current module. It is illegal for a function <i>declaration</i>
428to have any linkage type other than "externally visible".</a></p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]429
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]430</div>
431
432<!-- ======================================================================= -->
433<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]434 <a name="callingconv">Calling Conventions</a>
435</div>
436
437<div class="doc_text">
438
439<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
440and <a href="#i_invoke">invokes</a> can all have an optional calling convention
441specified for the call. The calling convention of any pair of dynamic
442caller/callee must match, or the behavior of the program is undefined. The
443following calling conventions are supported by LLVM, and more may be added in
444the future:</p>
445
446<dl>
447 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
448
449 <dd>This calling convention (the default if no other calling convention is
450 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]451 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]452 prototype and implemented declaration of the function (as does normal C).
453 </dd>
454
455 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
456
457 <dd>This calling convention attempts to make calls as fast as possible
458 (e.g. by passing things in registers). This calling convention allows the
459 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]460 without having to conform to an externally specified ABI. Implementations of
461 this convention should allow arbitrary tail call optimization to be supported.
462 This calling convention does not support varargs and requires the prototype of
463 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]464 </dd>
465
466 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
467
468 <dd>This calling convention attempts to make code in the caller as efficient
469 as possible under the assumption that the call is not commonly executed. As
470 such, these calls often preserve all registers so that the call does not break
471 any live ranges in the caller side. This calling convention does not support
472 varargs and requires the prototype of all callees to exactly match the
473 prototype of the function definition.
474 </dd>
475
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]476 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]477
478 <dd>Any calling convention may be specified by number, allowing
479 target-specific calling conventions to be used. Target specific calling
480 conventions start at 64.
481 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]482</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]483
484<p>More calling conventions can be added/defined on an as-needed basis, to
485support pascal conventions or any other well-known target-independent
486convention.</p>
487
488</div>
489
490<!-- ======================================================================= -->
491<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]492 <a name="globalvars">Global Variables</a>
493</div>
494
495<div class="doc_text">
496
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]497<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame^]498instead of run-time. Global variables may optionally be initialized, may have
499an explicit section to be placed in, and may
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]500have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]501variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]502contents of the variable will <b>never</b> be modified (enabling better
503optimization, allowing the global data to be placed in the read-only section of
504an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]505cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]506
507<p>
508LLVM explicitly allows <em>declarations</em> of global variables to be marked
509constant, even if the final definition of the global is not. This capability
510can be used to enable slightly better optimization of the program, but requires
511the language definition to guarantee that optimizations based on the
512'constantness' are valid for the translation units that do not include the
513definition.
514</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]515
516<p>As SSA values, global variables define pointer values that are in
517scope (i.e. they dominate) all basic blocks in the program. Global
518variables always define a pointer to their "content" type because they
519describe a region of memory, and all memory objects in LLVM are
520accessed through pointers.</p>
521
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame^]522<p>LLVM allows an explicit section to be specified for globals. If the target
523supports it, it will emit globals to the section specified.</p>
524
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]525<p>An explicit alignment may be specified for a global. If not present, or if
526the alignment is set to zero, the alignment of the global is set by the target
527to whatever it feels convenient. If an explicit alignment is specified, the
528global is forced to have at least that much alignment. All alignments must be
529a power of 2.</p>
530
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]531</div>
532
533
534<!-- ======================================================================= -->
535<div class="doc_subsection">
536 <a name="functionstructure">Functions</a>
537</div>
538
539<div class="doc_text">
540
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]541<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
542type</a>, an optional <a href="#callingconv">calling convention</a>, a return
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame^]543type, a function name, a (possibly empty) argument list, an optional section,
544an optional alignment, an opening curly brace,
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]545a list of basic blocks, and a closing curly brace. LLVM function declarations
546are defined with the "<tt>declare</tt>" keyword, an optional <a
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]547href="#callingconv">calling convention</a>, a return type, a function name,
548a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]549
550<p>A function definition contains a list of basic blocks, forming the CFG for
551the function. Each basic block may optionally start with a label (giving the
552basic block a symbol table entry), contains a list of instructions, and ends
553with a <a href="#terminators">terminator</a> instruction (such as a branch or
554function return).</p>
555
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]556<p>The first basic block in a program is special in two ways: it is immediately
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]557executed on entrance to the function, and it is not allowed to have predecessor
558basic blocks (i.e. there can not be any branches to the entry block of a
559function). Because the block can have no predecessors, it also cannot have any
560<a href="#i_phi">PHI nodes</a>.</p>
561
562<p>LLVM functions are identified by their name and type signature. Hence, two
563functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]564considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]565appropriately.</p>
566
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame^]567<p>LLVM allows an explicit section to be specified for functions. If the target
568supports it, it will emit functions to the section specified.</p>
569
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]570<p>An explicit alignment may be specified for a function. If not present, or if
571the alignment is set to zero, the alignment of the function is set by the target
572to whatever it feels convenient. If an explicit alignment is specified, the
573function is forced to have at least that much alignment. All alignments must be
574a power of 2.</p>
575
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]576</div>
577
578
579
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]580<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]581<div class="doc_section"> <a name="typesystem">Type System</a> </div>
582<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]583
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]584<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]585
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]586<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]587intermediate representation. Being typed enables a number of
588optimizations to be performed on the IR directly, without having to do
589extra analyses on the side before the transformation. A strong type
590system makes it easier to read the generated code and enables novel
591analyses and transformations that are not feasible to perform on normal
592three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]593
594</div>
595
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]596<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]597<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]598<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]599<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]600system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]601
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]602<table class="layout">
603 <tr class="layout">
604 <td class="left">
605 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]606 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]607 <tr><th>Type</th><th>Description</th></tr>
608 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]609 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
610 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
611 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
612 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
613 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]614 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]615 </tbody>
616 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]617 </td>
618 <td class="right">
619 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]620 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]621 <tr><th>Type</th><th>Description</th></tr>
622 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]623 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
624 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
625 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
626 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
627 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]628 </tbody>
629 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]630 </td>
631 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]632</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]633</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]634
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]635<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]636<div class="doc_subsubsection"> <a name="t_classifications">Type
637Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]638<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]639<p>These different primitive types fall into a few useful
640classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]641
642<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]643 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]644 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]645 <tr>
646 <td><a name="t_signed">signed</a></td>
647 <td><tt>sbyte, short, int, long, float, double</tt></td>
648 </tr>
649 <tr>
650 <td><a name="t_unsigned">unsigned</a></td>
651 <td><tt>ubyte, ushort, uint, ulong</tt></td>
652 </tr>
653 <tr>
654 <td><a name="t_integer">integer</a></td>
655 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
656 </tr>
657 <tr>
658 <td><a name="t_integral">integral</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]659 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
660 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]661 </tr>
662 <tr>
663 <td><a name="t_floating">floating point</a></td>
664 <td><tt>float, double</tt></td>
665 </tr>
666 <tr>
667 <td><a name="t_firstclass">first class</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]668 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
669 float, double, <a href="#t_pointer">pointer</a>,
670 <a href="#t_packed">packed</a></tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]671 </tr>
672 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]673</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]674
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]675<p>The <a href="#t_firstclass">first class</a> types are perhaps the
676most important. Values of these types are the only ones which can be
677produced by instructions, passed as arguments, or used as operands to
678instructions. This means that all structures and arrays must be
679manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]680</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]681
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]682<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]683<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]684
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]685<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]686
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]687<p>The real power in LLVM comes from the derived types in the system.
688This is what allows a programmer to represent arrays, functions,
689pointers, and other useful types. Note that these derived types may be
690recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]691
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]692</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]693
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]694<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]695<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]696
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]697<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]698
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]699<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]700
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]701<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]702sequentially in memory. The array type requires a size (number of
703elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]704
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]705<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]706
707<pre>
708 [&lt;# elements&gt; x &lt;elementtype&gt;]
709</pre>
710
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]711<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]712be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]713
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]714<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]715<table class="layout">
716 <tr class="layout">
717 <td class="left">
718 <tt>[40 x int ]</tt><br/>
719 <tt>[41 x int ]</tt><br/>
720 <tt>[40 x uint]</tt><br/>
721 </td>
722 <td class="left">
723 Array of 40 integer values.<br/>
724 Array of 41 integer values.<br/>
725 Array of 40 unsigned integer values.<br/>
726 </td>
727 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]728</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]729<p>Here are some examples of multidimensional arrays:</p>
730<table class="layout">
731 <tr class="layout">
732 <td class="left">
733 <tt>[3 x [4 x int]]</tt><br/>
734 <tt>[12 x [10 x float]]</tt><br/>
735 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
736 </td>
737 <td class="left">
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]738 3x4 array of integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]739 12x10 array of single precision floating point values.<br/>
740 2x3x4 array of unsigned integer values.<br/>
741 </td>
742 </tr>
743</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]744
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]745<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
746length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]747LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
748As a special case, however, zero length arrays are recognized to be variable
749length. This allows implementation of 'pascal style arrays' with the LLVM
750type "{ int, [0 x float]}", for example.</p>
751
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]752</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]753
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]754<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]755<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]756<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]757<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]758<p>The function type can be thought of as a function signature. It
759consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]760Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]761(which are structures of pointers to functions), for indirect function
762calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]763<p>
764The return type of a function type cannot be an aggregate type.
765</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]766<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]767<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]768<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]769specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]770which indicates that the function takes a variable number of arguments.
771Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]772 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]773<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]774<table class="layout">
775 <tr class="layout">
776 <td class="left">
777 <tt>int (int)</tt> <br/>
778 <tt>float (int, int *) *</tt><br/>
779 <tt>int (sbyte *, ...)</tt><br/>
780 </td>
781 <td class="left">
782 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
783 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]784 <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]785 returning <tt>float</tt>.<br/>
786 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
787 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
788 the signature for <tt>printf</tt> in LLVM.<br/>
789 </td>
790 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]791</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]792
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]793</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]794<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]795<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]796<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]797<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]798<p>The structure type is used to represent a collection of data members
799together in memory. The packing of the field types is defined to match
800the ABI of the underlying processor. The elements of a structure may
801be any type that has a size.</p>
802<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
803and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
804field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
805instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]806<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]807<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]808<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]809<table class="layout">
810 <tr class="layout">
811 <td class="left">
812 <tt>{ int, int, int }</tt><br/>
813 <tt>{ float, int (int) * }</tt><br/>
814 </td>
815 <td class="left">
816 a triple of three <tt>int</tt> values<br/>
817 A pair, where the first element is a <tt>float</tt> and the second element
818 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
819 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
820 </td>
821 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]822</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]823</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]824
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]825<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]826<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]827<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]828<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]829<p>As in many languages, the pointer type represents a pointer or
830reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]831<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]832<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]833<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]834<table class="layout">
835 <tr class="layout">
836 <td class="left">
837 <tt>[4x int]*</tt><br/>
838 <tt>int (int *) *</tt><br/>
839 </td>
840 <td class="left">
841 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
842 four <tt>int</tt> values<br/>
843 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattnera977c482005-02-19 02:22:14 +0000[diff] [blame]844 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]845 <tt>int</tt>.<br/>
846 </td>
847 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]848</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]849</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]850
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]851<!-- _______________________________________________________________________ -->
852<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]853<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]854
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]855<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]856
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]857<p>A packed type is a simple derived type that represents a vector
858of elements. Packed types are used when multiple primitive data
859are operated in parallel using a single instruction (SIMD).
860A packed type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]861elements) and an underlying primitive data type. Vectors must have a power
862of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]863considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]864
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]865<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]866
867<pre>
868 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
869</pre>
870
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]871<p>The number of elements is a constant integer value; elementtype may
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]872be any integral or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]873
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]874<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]875
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]876<table class="layout">
877 <tr class="layout">
878 <td class="left">
879 <tt>&lt;4 x int&gt;</tt><br/>
880 <tt>&lt;8 x float&gt;</tt><br/>
881 <tt>&lt;2 x uint&gt;</tt><br/>
882 </td>
883 <td class="left">
884 Packed vector of 4 integer values.<br/>
885 Packed vector of 8 floating-point values.<br/>
886 Packed vector of 2 unsigned integer values.<br/>
887 </td>
888 </tr>
889</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]890</div>
891
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]892<!-- _______________________________________________________________________ -->
893<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
894<div class="doc_text">
895
896<h5>Overview:</h5>
897
898<p>Opaque types are used to represent unknown types in the system. This
899corresponds (for example) to the C notion of a foward declared structure type.
900In LLVM, opaque types can eventually be resolved to any type (not just a
901structure type).</p>
902
903<h5>Syntax:</h5>
904
905<pre>
906 opaque
907</pre>
908
909<h5>Examples:</h5>
910
911<table class="layout">
912 <tr class="layout">
913 <td class="left">
914 <tt>opaque</tt>
915 </td>
916 <td class="left">
917 An opaque type.<br/>
918 </td>
919 </tr>
920</table>
921</div>
922
923
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]924<!-- *********************************************************************** -->
925<div class="doc_section"> <a name="constants">Constants</a> </div>
926<!-- *********************************************************************** -->
927
928<div class="doc_text">
929
930<p>LLVM has several different basic types of constants. This section describes
931them all and their syntax.</p>
932
933</div>
934
935<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]936<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]937
938<div class="doc_text">
939
940<dl>
941 <dt><b>Boolean constants</b></dt>
942
943 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
944 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
945 </dd>
946
947 <dt><b>Integer constants</b></dt>
948
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]949 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]950 href="#t_integer">integer</a> type. Negative numbers may be used with signed
951 integer types.
952 </dd>
953
954 <dt><b>Floating point constants</b></dt>
955
956 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
957 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]958 notation (see below). Floating point constants must have a <a
959 href="#t_floating">floating point</a> type. </dd>
960
961 <dt><b>Null pointer constants</b></dt>
962
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]963 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]964 and must be of <a href="#t_pointer">pointer type</a>.</dd>
965
966</dl>
967
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]968<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]969of floating point constants. For example, the form '<tt>double
9700x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
9714.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]972(and the only time that they are generated by the disassembler) is when a
973floating point constant must be emitted but it cannot be represented as a
974decimal floating point number. For example, NaN's, infinities, and other
975special values are represented in their IEEE hexadecimal format so that
976assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]977
978</div>
979
980<!-- ======================================================================= -->
981<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
982</div>
983
984<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]985<p>Aggregate constants arise from aggregation of simple constants
986and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]987
988<dl>
989 <dt><b>Structure constants</b></dt>
990
991 <dd>Structure constants are represented with notation similar to structure
992 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]993 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
994 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
995 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]996 types of elements must match those specified by the type.
997 </dd>
998
999 <dt><b>Array constants</b></dt>
1000
1001 <dd>Array constants are represented with notation similar to array type
1002 definitions (a comma separated list of elements, surrounded by square brackets
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1003 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1004 constants must have <a href="#t_array">array type</a>, and the number and
1005 types of elements must match those specified by the type.
1006 </dd>
1007
1008 <dt><b>Packed constants</b></dt>
1009
1010 <dd>Packed constants are represented with notation similar to packed type
1011 definitions (a comma separated list of elements, surrounded by
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1012 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]1013 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
1014 href="#t_packed">packed type</a>, and the number and types of elements must
1015 match those specified by the type.
1016 </dd>
1017
1018 <dt><b>Zero initialization</b></dt>
1019
1020 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1021 value to zero of <em>any</em> type, including scalar and aggregate types.
1022 This is often used to avoid having to print large zero initializers (e.g. for
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1023 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1024 initializers.
1025 </dd>
1026</dl>
1027
1028</div>
1029
1030<!-- ======================================================================= -->
1031<div class="doc_subsection">
1032 <a name="globalconstants">Global Variable and Function Addresses</a>
1033</div>
1034
1035<div class="doc_text">
1036
1037<p>The addresses of <a href="#globalvars">global variables</a> and <a
1038href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1039constants. These constants are explicitly referenced when the <a
1040href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1041href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1042file:</p>
1043
1044<pre>
1045 %X = global int 17
1046 %Y = global int 42
1047 %Z = global [2 x int*] [ int* %X, int* %Y ]
1048</pre>
1049
1050</div>
1051
1052<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1053<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1054<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1055 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1056 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1057 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1058
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1059 <p>Undefined values indicate to the compiler that the program is well defined
1060 no matter what value is used, giving the compiler more freedom to optimize.
1061 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1062</div>
1063
1064<!-- ======================================================================= -->
1065<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1066</div>
1067
1068<div class="doc_text">
1069
1070<p>Constant expressions are used to allow expressions involving other constants
1071to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1072href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1073that does not have side effects (e.g. load and call are not supported). The
1074following is the syntax for constant expressions:</p>
1075
1076<dl>
1077 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1078
1079 <dd>Cast a constant to another type.</dd>
1080
1081 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1082
1083 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1084 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1085 instruction, the index list may have zero or more indexes, which are required
1086 to make sense for the type of "CSTPTR".</dd>
1087
1088 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1089
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1090 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1091 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1092 binary</a> operations. The constraints on operands are the same as those for
1093 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1094 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1095</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1096</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1097
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1098<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1099<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1100<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1101
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1102<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1103
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1104<p>The LLVM instruction set consists of several different
1105classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1106instructions</a>, <a href="#binaryops">binary instructions</a>,
1107<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1108 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1109instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1110
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1111</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1112
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1113<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1114<div class="doc_subsection"> <a name="terminators">Terminator
1115Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1116
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1117<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1118
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1119<p>As mentioned <a href="#functionstructure">previously</a>, every
1120basic block in a program ends with a "Terminator" instruction, which
1121indicates which block should be executed after the current block is
1122finished. These terminator instructions typically yield a '<tt>void</tt>'
1123value: they produce control flow, not values (the one exception being
1124the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1125<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1126 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1127instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1128the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1129 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1130 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1131
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1132</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1133
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1134<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1135<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1136Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1137<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1138<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1139<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]1140 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1141</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1142<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1143<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1144value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1145<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1146returns a value and then causes control flow, and one that just causes
1147control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1148<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1149<p>The '<tt>ret</tt>' instruction may return any '<a
1150 href="#t_firstclass">first class</a>' type. Notice that a function is
1151not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1152instruction inside of the function that returns a value that does not
1153match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1154<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1155<p>When the '<tt>ret</tt>' instruction is executed, control flow
1156returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1157 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1158the instruction after the call. If the caller was an "<a
1159 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1160at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1161returns a value, that value shall set the call or invoke instruction's
1162return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1163<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1164<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1165 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1166</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1167</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1168<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1169<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1170<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1171<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1172<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]1173</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1174<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1175<p>The '<tt>br</tt>' instruction is used to cause control flow to
1176transfer to a different basic block in the current function. There are
1177two forms of this instruction, corresponding to a conditional branch
1178and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1179<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1180<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1181single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1182unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1183value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1184<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1185<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1186argument is evaluated. If the value is <tt>true</tt>, control flows
1187to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1188control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1189<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1190<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
1191 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]1192</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1193<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1194<div class="doc_subsubsection">
1195 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1196</div>
1197
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1198<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1199<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1200
1201<pre>
1202 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1203</pre>
1204
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1205<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1206
1207<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1208several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1209instruction, allowing a branch to occur to one of many possible
1210destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1211
1212
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1213<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1214
1215<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1216comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1217an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1218table is not allowed to contain duplicate constant entries.</p>
1219
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1220<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1221
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1222<p>The <tt>switch</tt> instruction specifies a table of values and
1223destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1224table is searched for the given value. If the value is found, control flow is
1225transfered to the corresponding destination; otherwise, control flow is
1226transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1227
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1228<h5>Implementation:</h5>
1229
1230<p>Depending on properties of the target machine and the particular
1231<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1232ways. For example, it could be generated as a series of chained conditional
1233branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1234
1235<h5>Example:</h5>
1236
1237<pre>
1238 <i>; Emulate a conditional br instruction</i>
1239 %Val = <a href="#i_cast">cast</a> bool %value to int
1240 switch int %Val, label %truedest [int 0, label %falsedest ]
1241
1242 <i>; Emulate an unconditional br instruction</i>
1243 switch uint 0, label %dest [ ]
1244
1245 <i>; Implement a jump table:</i>
1246 switch uint %val, label %otherwise [ uint 0, label %onzero
1247 uint 1, label %onone
1248 uint 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1249</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1250</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1251
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1252<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1253<div class="doc_subsubsection">
1254 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1255</div>
1256
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1257<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1258
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1259<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1260
1261<pre>
1262 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1263 to label &lt;normal label&gt; except label &lt;exception label&gt;
1264</pre>
1265
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1266<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1267
1268<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1269function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1270'<tt>normal</tt>' label or the
1271'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1272"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1273"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1274href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1275continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1276
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1277<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1278
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1279<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1280
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1281<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1282 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1283 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1284 convention</a> the call should use. If none is specified, the call defaults
1285 to using C calling conventions.
1286 </li>
1287 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1288 function value being invoked. In most cases, this is a direct function
1289 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1290 an arbitrary pointer to function value.
1291 </li>
1292
1293 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1294 function to be invoked. </li>
1295
1296 <li>'<tt>function args</tt>': argument list whose types match the function
1297 signature argument types. If the function signature indicates the function
1298 accepts a variable number of arguments, the extra arguments can be
1299 specified. </li>
1300
1301 <li>'<tt>normal label</tt>': the label reached when the called function
1302 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1303
1304 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1305 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1306
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1307</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1308
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1309<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1310
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1311<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1312href="#i_call">call</a></tt>' instruction in most regards. The primary
1313difference is that it establishes an association with a label, which is used by
1314the runtime library to unwind the stack.</p>
1315
1316<p>This instruction is used in languages with destructors to ensure that proper
1317cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1318exception. Additionally, this is important for implementation of
1319'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1320
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1321<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1322<pre>
1323 %retval = invoke int %Test(int 15) to label %Continue
1324 except label %TestCleanup <i>; {int}:retval set</i>
1325 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
1326 except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1327</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1328</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1329
1330
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1331<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1332
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1333<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1334Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1335
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1336<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1337
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1338<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1339<pre>
1340 unwind
1341</pre>
1342
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1343<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1344
1345<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1346at the first callee in the dynamic call stack which used an <a
1347href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1348primarily used to implement exception handling.</p>
1349
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1350<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1351
1352<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1353immediately halt. The dynamic call stack is then searched for the first <a
1354href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1355execution continues at the "exceptional" destination block specified by the
1356<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1357dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1358</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1359
1360<!-- _______________________________________________________________________ -->
1361
1362<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1363Instruction</a> </div>
1364
1365<div class="doc_text">
1366
1367<h5>Syntax:</h5>
1368<pre>
1369 unreachable
1370</pre>
1371
1372<h5>Overview:</h5>
1373
1374<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1375instruction is used to inform the optimizer that a particular portion of the
1376code is not reachable. This can be used to indicate that the code after a
1377no-return function cannot be reached, and other facts.</p>
1378
1379<h5>Semantics:</h5>
1380
1381<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1382</div>
1383
1384
1385
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1386<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1387<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1388<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1389<p>Binary operators are used to do most of the computation in a
1390program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1391produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1392multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1393The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1394necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1395<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1396</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1397<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1398<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1399Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1400<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1401<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1402<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]1403</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1404<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1405<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1406<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1407<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1408 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1409 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1410Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1411<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1412<p>The value produced is the integer or floating point sum of the two
1413operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1414<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1415<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]1416</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1417</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1418<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1419<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1420Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1421<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1422<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1423<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]1424</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1425<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1426<p>The '<tt>sub</tt>' instruction returns the difference of its two
1427operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1428<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1429instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1430<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1431<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1432 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1433values.
1434This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1435Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1436<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1437<p>The value produced is the integer or floating point difference of
1438the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1439<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1440<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]1441 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1442</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1443</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1444<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1445<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1446Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1447<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1448<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1449<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]1450</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1451<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1452<p>The '<tt>mul</tt>' instruction returns the product of its two
1453operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1454<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1455<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1456 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1457values.
1458This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1459Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1460<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1461<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1462two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1463<p>There is no signed vs unsigned multiplication. The appropriate
1464action is taken based on the type of the operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1465<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1466<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]1467</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1468</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1469<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1470<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1471Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1472<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1473<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1474<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1475</pre>
1476<h5>Overview:</h5>
1477<p>The '<tt>div</tt>' instruction returns the quotient of its two
1478operands.</p>
1479<h5>Arguments:</h5>
1480<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1481 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1482values.
1483This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1484Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1485<h5>Semantics:</h5>
1486<p>The value produced is the integer or floating point quotient of the
1487two operands.</p>
1488<h5>Example:</h5>
1489<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1490</pre>
1491</div>
1492<!-- _______________________________________________________________________ -->
1493<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1494Instruction</a> </div>
1495<div class="doc_text">
1496<h5>Syntax:</h5>
1497<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1498</pre>
1499<h5>Overview:</h5>
1500<p>The '<tt>rem</tt>' instruction returns the remainder from the
1501division of its two operands.</p>
1502<h5>Arguments:</h5>
1503<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1504 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1505values.
1506This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1507Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1508<h5>Semantics:</h5>
1509<p>This returns the <i>remainder</i> of a division (where the result
1510has the same sign as the divisor), not the <i>modulus</i> (where the
1511result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1512information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1513 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1514Math Forum</a>.</p>
1515<h5>Example:</h5>
1516<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1517</pre>
1518</div>
1519<!-- _______________________________________________________________________ -->
1520<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1521Instructions</a> </div>
1522<div class="doc_text">
1523<h5>Syntax:</h5>
1524<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]1525 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1526 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1527 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1528 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1529 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1530</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1531<h5>Overview:</h5>
1532<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1533value based on a comparison of their two operands.</p>
1534<h5>Arguments:</h5>
1535<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1536be of <a href="#t_firstclass">first class</a> type (it is not possible
1537to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1538or '<tt>void</tt>' values, etc...). Both arguments must have identical
1539types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1540<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1541<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1542value if both operands are equal.<br>
1543The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1544value if both operands are unequal.<br>
1545The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1546value if the first operand is less than the second operand.<br>
1547The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1548value if the first operand is greater than the second operand.<br>
1549The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1550value if the first operand is less than or equal to the second operand.<br>
1551The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1552value if the first operand is greater than or equal to the second
1553operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1554<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1555<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1556 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1557 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1558 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1559 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1560 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1561</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1562</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1563<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1564<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1565Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1566<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1567<p>Bitwise binary operators are used to do various forms of
1568bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1569instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1570instructions. They require two operands, execute an operation on them,
1571and produce a single value. The resulting value of the bitwise binary
1572operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1573</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1574<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1575<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1576Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1577<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1578<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1579<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]1580</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1581<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1582<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1583its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1584<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1585<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1586 href="#t_integral">integral</a> values. Both arguments must have
1587identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1588<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1589<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1590<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1591<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1592<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1593 <tbody>
1594 <tr>
1595 <td>In0</td>
1596 <td>In1</td>
1597 <td>Out</td>
1598 </tr>
1599 <tr>
1600 <td>0</td>
1601 <td>0</td>
1602 <td>0</td>
1603 </tr>
1604 <tr>
1605 <td>0</td>
1606 <td>1</td>
1607 <td>0</td>
1608 </tr>
1609 <tr>
1610 <td>1</td>
1611 <td>0</td>
1612 <td>0</td>
1613 </tr>
1614 <tr>
1615 <td>1</td>
1616 <td>1</td>
1617 <td>1</td>
1618 </tr>
1619 </tbody>
1620</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1621</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1622<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1623<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]1624 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1625 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1626</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1627</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1628<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1629<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1630<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1631<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1632<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]1633</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1634<h5>Overview:</h5>
1635<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1636or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1637<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1638<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1639 href="#t_integral">integral</a> values. Both arguments must have
1640identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1641<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1642<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1643<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1644<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1645<table border="1" cellspacing="0" cellpadding="4">
1646 <tbody>
1647 <tr>
1648 <td>In0</td>
1649 <td>In1</td>
1650 <td>Out</td>
1651 </tr>
1652 <tr>
1653 <td>0</td>
1654 <td>0</td>
1655 <td>0</td>
1656 </tr>
1657 <tr>
1658 <td>0</td>
1659 <td>1</td>
1660 <td>1</td>
1661 </tr>
1662 <tr>
1663 <td>1</td>
1664 <td>0</td>
1665 <td>1</td>
1666 </tr>
1667 <tr>
1668 <td>1</td>
1669 <td>1</td>
1670 <td>1</td>
1671 </tr>
1672 </tbody>
1673</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1674</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1675<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1676<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]1677 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1678 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1679</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1680</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1681<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1682<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1683Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1684<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1685<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1686<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]1687</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1688<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1689<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1690or of its two operands. The <tt>xor</tt> is used to implement the
1691"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1692<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1693<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1694 href="#t_integral">integral</a> values. Both arguments must have
1695identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1696<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1697<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1698<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1699<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1700<table border="1" cellspacing="0" cellpadding="4">
1701 <tbody>
1702 <tr>
1703 <td>In0</td>
1704 <td>In1</td>
1705 <td>Out</td>
1706 </tr>
1707 <tr>
1708 <td>0</td>
1709 <td>0</td>
1710 <td>0</td>
1711 </tr>
1712 <tr>
1713 <td>0</td>
1714 <td>1</td>
1715 <td>1</td>
1716 </tr>
1717 <tr>
1718 <td>1</td>
1719 <td>0</td>
1720 <td>1</td>
1721 </tr>
1722 <tr>
1723 <td>1</td>
1724 <td>1</td>
1725 <td>0</td>
1726 </tr>
1727 </tbody>
1728</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1729</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1730<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1731<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1732<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]1733 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1734 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1735 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1736</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1737</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1738<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1739<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1740Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1741<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1742<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1743<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]1744</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1745<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1746<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1747the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1748<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1749<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1750 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1751type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1752<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1753<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]1754<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1755<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]1756 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1757 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1758</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1759</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1760<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1761<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1762Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1763<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1764<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1765<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]1766</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1767<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1768<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1769the right a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1770<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1771<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1772 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1773type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1774<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1775<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1776most significant bit is duplicated in the newly free'd bit positions.
1777If the first argument is unsigned, zero bits shall fill the empty
1778positions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1779<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1780<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]1781 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1782 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1783 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1784 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1785</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1786</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1787
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1788<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1789<div class="doc_subsection">
1790 <a name="memoryops">Memory Access Operations</a>
1791</div>
1792
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1793<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1794
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1795<p>A key design point of an SSA-based representation is how it
1796represents memory. In LLVM, no memory locations are in SSA form, which
1797makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1798allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1799
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1800</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1801
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1802<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1803<div class="doc_subsubsection">
1804 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
1805</div>
1806
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1807<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1808
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1809<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1810
1811<pre>
1812 &lt;result&gt; = malloc &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1813</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1814
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1815<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1816
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1817<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1818heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1819
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1820<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1821
1822<p>The '<tt>malloc</tt>' instruction allocates
1823<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]1824bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1825appropriate type to the program. If "NumElements" is specified, it is the
1826number of elements allocated. If an alignment is specified, the value result
1827of the allocation is guaranteed to be aligned to at least that boundary. If
1828not specified, or if zero, the target can choose to align the allocation on any
1829convenient boundary.</p>
1830
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1831<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1832
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1833<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1834
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1835<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1836a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1837
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1838<h5>Example:</h5>
1839
1840<pre>
1841 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
1842
1843 %size = <a 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]1844 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1845 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1846 %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
1847 %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1848</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1849</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1850
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1851<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1852<div class="doc_subsubsection">
1853 <a name="i_free">'<tt>free</tt>' Instruction</a>
1854</div>
1855
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1856<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1857
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1858<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1859
1860<pre>
1861 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1862</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1863
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1864<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1865
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1866<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1867memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1868
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1869<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1870
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1871<p>'<tt>value</tt>' shall be a pointer value that points to a value
1872that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1873instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1874
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1875<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1876
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1877<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1878after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1879
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1880<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1881
1882<pre>
1883 %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]1884 free [4 x ubyte]* %array
1885</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1886</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1887
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1888<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1889<div class="doc_subsubsection">
1890 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
1891</div>
1892
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1893<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1894
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1895<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1896
1897<pre>
1898 &lt;result&gt; = alloca &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1899</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1900
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1901<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1902
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1903<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1904stack frame of the procedure that is live until the current function
1905returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1906
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1907<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1908
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1909<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1910bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1911appropriate type to the program. If "NumElements" is specified, it is the
1912number of elements allocated. If an alignment is specified, the value result
1913of the allocation is guaranteed to be aligned to at least that boundary. If
1914not specified, or if zero, the target can choose to align the allocation on any
1915convenient boundary.</p>
1916
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1917<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1918
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1919<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1920
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1921<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1922memory is automatically released when the function returns. The '<tt>alloca</tt>'
1923instruction is commonly used to represent automatic variables that must
1924have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]1925 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1926instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1927
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1928<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1929
1930<pre>
1931 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1932 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1933 %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
1934 %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1935</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1936</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1937
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1938<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1939<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1940Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1941<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1942<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1943<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]1944<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1945<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1946<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1947<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1948address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]1949 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1950marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1951the number or order of execution of this <tt>load</tt> with other
1952volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1953instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1954<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1955<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1956<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1957<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1958 <a
1959 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1960 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1961</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1962</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1963<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1964<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1965Instruction</a> </div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1966<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1967<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]1968 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]1969</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1970<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1971<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1972<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1973<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1974to store and an address in which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1975operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1976operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1977optimizer is not allowed to modify the number or order of execution of
1978this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1979 href="#i_store">store</a></tt> instructions.</p>
1980<h5>Semantics:</h5>
1981<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1982at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1983<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1984<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1985 <a
1986 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1987 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1988</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1989<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1990<div class="doc_subsubsection">
1991 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
1992</div>
1993
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1994<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1995<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1996<pre>
1997 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
1998</pre>
1999
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2000<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2001
2002<p>
2003The '<tt>getelementptr</tt>' instruction is used to get the address of a
2004subelement of an aggregate data structure.</p>
2005
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2006<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2007
2008<p>This instruction takes a list of integer constants that indicate what
2009elements of the aggregate object to index to. The actual types of the arguments
2010provided depend on the type of the first pointer argument. The
2011'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2012levels of a structure or to a specific index in an array. When indexing into a
2013structure, only <tt>uint</tt>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2014integer constants are allowed. When indexing into an array or pointer,
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2015<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
2016
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2017<p>For example, let's consider a C code fragment and how it gets
2018compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2019
2020<pre>
2021 struct RT {
2022 char A;
2023 int B[10][20];
2024 char C;
2025 };
2026 struct ST {
2027 int X;
2028 double Y;
2029 struct RT Z;
2030 };
2031
2032 int *foo(struct ST *s) {
2033 return &amp;s[1].Z.B[5][13];
2034 }
2035</pre>
2036
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2037<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2038
2039<pre>
2040 %RT = type { sbyte, [10 x [20 x int]], sbyte }
2041 %ST = type { int, double, %RT }
2042
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2043 implementation
2044
2045 int* %foo(%ST* %s) {
2046 entry:
2047 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2048 ret int* %reg
2049 }
2050</pre>
2051
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2052<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2053
2054<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2055on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2056and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
2057<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]2058types require <tt>uint</tt> <b>constants</b>.</p>
2059
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2060<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]2061type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
2062}</tt>' type, a structure. The second index indexes into the third element of
2063the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
2064sbyte }</tt>' type, another structure. The third index indexes into the second
2065element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
2066array. The two dimensions of the array are subscripted into, yielding an
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2067'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2068to this element, thus computing a value of '<tt>int*</tt>' type.</p>
2069
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2070<p>Note that it is perfectly legal to index partially through a
2071structure, returning a pointer to an inner element. Because of this,
2072the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2073
2074<pre>
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]2075 int* %foo(%ST* %s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2076 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
2077 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
2078 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
2079 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
2080 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
2081 ret int* %t5
2082 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2083</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2084
2085<p>Note that it is undefined to access an array out of bounds: array and
2086pointer indexes must always be within the defined bounds of the array type.
2087The one exception for this rules is zero length arrays. These arrays are
2088defined to be accessible as variable length arrays, which requires access
2089beyond the zero'th element.</p>
2090
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2091<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2092
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2093<pre>
2094 <i>; yields [12 x ubyte]*:aptr</i>
2095 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
2096</pre>
2097
2098</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2099<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2100<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2101<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]2102<p>The instructions in this category are the "miscellaneous"
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2103instructions, which defy better classification.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2104</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2105<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2106<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2107Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2108<div class="doc_text">
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2109<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2110<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]2111<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2112<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2113the SSA graph representing the function.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2114<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2115<p>The type of the incoming values are specified with the first type
2116field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2117as arguments, with one pair for each predecessor basic block of the
2118current block. Only values of <a href="#t_firstclass">first class</a>
2119type may be used as the value arguments to the PHI node. Only labels
2120may be used as the label arguments.</p>
2121<p>There must be no non-phi instructions between the start of a basic
2122block and the PHI instructions: i.e. PHI instructions must be first in
2123a basic block.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2124<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2125<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2126value specified by the parameter, depending on which basic block we
2127came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2128<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2129<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]2130</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2131
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2132<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2133<div class="doc_subsubsection">
2134 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2135</div>
2136
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2137<div class="doc_text">
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2138
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2139<h5>Syntax:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2140
2141<pre>
2142 &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]2143</pre>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2144
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2145<h5>Overview:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2146
2147<p>
2148The '<tt>cast</tt>' instruction is used as the primitive means to convert
2149integers to floating point, change data type sizes, and break type safety (by
2150casting pointers).
2151</p>
2152
2153
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2154<h5>Arguments:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2155
2156<p>
2157The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2158class value, and a type to cast it to, which must also be a <a
2159href="#t_firstclass">first class</a> type.
2160</p>
2161
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2162<h5>Semantics:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2163
2164<p>
2165This instruction follows the C rules for explicit casts when determining how the
2166data being cast must change to fit in its new container.
2167</p>
2168
2169<p>
2170When casting to bool, any value that would be considered true in the context of
2171a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2172all else are '<tt>false</tt>'.
2173</p>
2174
2175<p>
2176When extending an integral value from a type of one signness to another (for
2177example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2178<b>source</b> value is signed, and zero-extended if the source value is
2179unsigned. <tt>bool</tt> values are always zero extended into either zero or
2180one.
2181</p>
2182
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2183<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2184
2185<pre>
2186 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]2187 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2188</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2189</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2190
2191<!-- _______________________________________________________________________ -->
2192<div class="doc_subsubsection">
2193 <a name="i_select">'<tt>select</tt>' Instruction</a>
2194</div>
2195
2196<div class="doc_text">
2197
2198<h5>Syntax:</h5>
2199
2200<pre>
2201 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2202</pre>
2203
2204<h5>Overview:</h5>
2205
2206<p>
2207The '<tt>select</tt>' instruction is used to choose one value based on a
2208condition, without branching.
2209</p>
2210
2211
2212<h5>Arguments:</h5>
2213
2214<p>
2215The '<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.
2216</p>
2217
2218<h5>Semantics:</h5>
2219
2220<p>
2221If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2222value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2223</p>
2224
2225<h5>Example:</h5>
2226
2227<pre>
2228 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2229</pre>
2230</div>
2231
2232
2233
2234
2235
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2236<!-- _______________________________________________________________________ -->
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2237<div class="doc_subsubsection">
2238 <a name="i_call">'<tt>call</tt>' Instruction</a>
2239</div>
2240
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2241<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2242
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2243<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2244<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2245 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2246</pre>
2247
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2248<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2249
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2250<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2251
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2252<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2253
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2254<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2255
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2256<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2257 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2258 <p>The optional "tail" marker indicates whether the callee function accesses
2259 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2260 function call is eligible for tail call optimization. Note that calls may
2261 be marked "tail" even if they do not occur before a <a
2262 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2263 </li>
2264 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2265 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2266 convention</a> the call should use. If none is specified, the call defaults
2267 to using C calling conventions.
2268 </li>
2269 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2270 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2271 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2272 signature. This type can be omitted if the function is not varargs and
2273 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2274 </li>
2275 <li>
2276 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2277 be invoked. In most cases, this is a direct function invocation, but
2278 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2279 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2280 </li>
2281 <li>
2282 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]2283 function signature argument types. All arguments must be of
2284 <a href="#t_firstclass">first class</a> type. If the function signature
2285 indicates the function accepts a variable number of arguments, the extra
2286 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2287 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2288</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2289
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2290<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2291
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2292<p>The '<tt>call</tt>' instruction is used to cause control flow to
2293transfer to a specified function, with its incoming arguments bound to
2294the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2295instruction in the called function, control flow continues with the
2296instruction after the function call, and the return value of the
2297function is bound to the result argument. This is a simpler case of
2298the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2299
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2300<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2301
2302<pre>
2303 %retval = call int %test(int %argc)
2304 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2305 %X = tail call int %foo()
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2306 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2307</pre>
2308
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2309</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2310
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2311<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2312<div class="doc_subsubsection">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2313 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
2314</div>
2315
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2316<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2317
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2318<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2319
2320<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2321 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2322</pre>
2323
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2324<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2325
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2326<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2327the "variable argument" area of a function call. It is used to implement the
2328<tt>va_arg</tt> macro in C.</p>
2329
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2330<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2331
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2332<p>This instruction takes a <tt>va_list*</tt> value and the type of
2333the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]2334increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2335actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2336
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2337<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2338
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2339<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
2340type from the specified <tt>va_list</tt> and causes the
2341<tt>va_list</tt> to point to the next argument. For more information,
2342see the variable argument handling <a href="#int_varargs">Intrinsic
2343Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2344
2345<p>It is legal for this instruction to be called in a function which does not
2346take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2347function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2348
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2349<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2350href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2351argument.</p>
2352
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2353<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2354
2355<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2356
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2357</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2358
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2359<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2360<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2361<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2362
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2363<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2364
2365<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2366well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2367restrictions. Overall, these instructions represent an extension mechanism for
2368the LLVM language that does not require changing all of the transformations in
2369LLVM to add to the language (or the bytecode reader/writer, the parser,
2370etc...).</p>
2371
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2372<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
2373prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2374this. Intrinsic functions must always be external functions: you cannot define
2375the body of intrinsic functions. Intrinsic functions may only be used in call
2376or invoke instructions: it is illegal to take the address of an intrinsic
2377function. Additionally, because intrinsic functions are part of the LLVM
2378language, it is required that they all be documented here if any are added.</p>
2379
2380
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2381<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]2382href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2383</p>
2384
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2385</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2386
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2387<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2388<div class="doc_subsection">
2389 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2390</div>
2391
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2392<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2393
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2394<p>Variable argument support is defined in LLVM with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2395 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
2396intrinsic functions. These functions are related to the similarly
2397named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2398
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2399<p>All of these functions operate on arguments that use a
2400target-specific value type "<tt>va_list</tt>". The LLVM assembly
2401language reference manual does not define what this type is, so all
2402transformations should be prepared to handle intrinsics with any type
2403used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2404
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2405<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2406instruction and the variable argument handling intrinsic functions are
2407used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2408
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2409<pre>
2410int %test(int %X, ...) {
2411 ; Initialize variable argument processing
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2412 %ap = alloca sbyte*
2413 call void %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2414
2415 ; Read a single integer argument
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2416 %tmp = va_arg sbyte** %ap, int
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2417
2418 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2419 %aq = alloca sbyte*
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2420 call void %<a href="#i_va_copy">llvm.va_copy</a>(sbyte** %aq, sbyte** %ap)
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2421 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2422
2423 ; Stop processing of arguments.
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2424 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2425 ret int %tmp
2426}
2427</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2428</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2429
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2430<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2431<div class="doc_subsubsection">
2432 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2433</div>
2434
2435
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2436<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2437<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2438<pre> declare void %llvm.va_start(&lt;va_list&gt;* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2439<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2440<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
2441<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
2442href="#i_va_arg">va_arg</a></tt>.</p>
2443
2444<h5>Arguments:</h5>
2445
2446<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
2447
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2448<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2449
2450<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
2451macro available in C. In a target-dependent way, it initializes the
2452<tt>va_list</tt> element the argument points to, so that the next call to
2453<tt>va_arg</tt> will produce the first variable argument passed to the function.
2454Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2455last argument of the function, the compiler can figure that out.</p>
2456
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2457</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2458
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2459<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2460<div class="doc_subsubsection">
2461 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2462</div>
2463
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2464<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2465<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2466<pre> declare void %llvm.va_end(&lt;va_list*&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2467<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2468<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2469which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2470or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2471<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2472<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2473<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2474<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]2475macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2476Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2477 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2478with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2479</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2480
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2481<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2482<div class="doc_subsubsection">
2483 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2484</div>
2485
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2486<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2487
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2488<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2489
2490<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2491 declare void %llvm.va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2492 &lt;va_list&gt;* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2493</pre>
2494
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2495<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2496
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2497<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
2498the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2499
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2500<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2501
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2502<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2503The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2504
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2505
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2506<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2507
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2508<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
2509available in C. In a target-dependent way, it copies the source
2510<tt>va_list</tt> element into the destination list. This intrinsic is necessary
2511because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2512arbitrarily complex and require memory allocation, for example.</p>
2513
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2514</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2515
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2516<!-- ======================================================================= -->
2517<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2518 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2519</div>
2520
2521<div class="doc_text">
2522
2523<p>
2524LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2525Collection</a> requires the implementation and generation of these intrinsics.
2526These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2527stack</a>, as well as garbage collector implementations that require <a
2528href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2529Front-ends for type-safe garbage collected languages should generate these
2530intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2531href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2532</p>
2533</div>
2534
2535<!-- _______________________________________________________________________ -->
2536<div class="doc_subsubsection">
2537 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2538</div>
2539
2540<div class="doc_text">
2541
2542<h5>Syntax:</h5>
2543
2544<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2545 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2546</pre>
2547
2548<h5>Overview:</h5>
2549
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2550<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]2551the code generator, and allows some metadata to be associated with it.</p>
2552
2553<h5>Arguments:</h5>
2554
2555<p>The first argument specifies the address of a stack object that contains the
2556root pointer. The second pointer (which must be either a constant or a global
2557value address) contains the meta-data to be associated with the root.</p>
2558
2559<h5>Semantics:</h5>
2560
2561<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2562location. At compile-time, the code generator generates information to allow
2563the runtime to find the pointer at GC safe points.
2564</p>
2565
2566</div>
2567
2568
2569<!-- _______________________________________________________________________ -->
2570<div class="doc_subsubsection">
2571 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2572</div>
2573
2574<div class="doc_text">
2575
2576<h5>Syntax:</h5>
2577
2578<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2579 declare sbyte* %llvm.gcread(sbyte** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2580</pre>
2581
2582<h5>Overview:</h5>
2583
2584<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2585locations, allowing garbage collector implementations that require read
2586barriers.</p>
2587
2588<h5>Arguments:</h5>
2589
2590<p>The argument is the address to read from, which should be an address
2591allocated from the garbage collector.</p>
2592
2593<h5>Semantics:</h5>
2594
2595<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2596instruction, but may be replaced with substantially more complex code by the
2597garbage collector runtime, as needed.</p>
2598
2599</div>
2600
2601
2602<!-- _______________________________________________________________________ -->
2603<div class="doc_subsubsection">
2604 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2605</div>
2606
2607<div class="doc_text">
2608
2609<h5>Syntax:</h5>
2610
2611<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2612 declare void %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2613</pre>
2614
2615<h5>Overview:</h5>
2616
2617<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2618locations, allowing garbage collector implementations that require write
2619barriers (such as generational or reference counting collectors).</p>
2620
2621<h5>Arguments:</h5>
2622
2623<p>The first argument is the reference to store, and the second is the heap
2624location to store to.</p>
2625
2626<h5>Semantics:</h5>
2627
2628<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2629instruction, but may be replaced with substantially more complex code by the
2630garbage collector runtime, as needed.</p>
2631
2632</div>
2633
2634
2635
2636<!-- ======================================================================= -->
2637<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2638 <a name="int_codegen">Code Generator Intrinsics</a>
2639</div>
2640
2641<div class="doc_text">
2642<p>
2643These intrinsics are provided by LLVM to expose special features that may only
2644be implemented with code generator support.
2645</p>
2646
2647</div>
2648
2649<!-- _______________________________________________________________________ -->
2650<div class="doc_subsubsection">
2651 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2652</div>
2653
2654<div class="doc_text">
2655
2656<h5>Syntax:</h5>
2657<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2658 declare void* %llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2659</pre>
2660
2661<h5>Overview:</h5>
2662
2663<p>
2664The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2665indicating the return address of the current function or one of its callers.
2666</p>
2667
2668<h5>Arguments:</h5>
2669
2670<p>
2671The argument to this intrinsic indicates which function to return the address
2672for. Zero indicates the calling function, one indicates its caller, etc. The
2673argument is <b>required</b> to be a constant integer value.
2674</p>
2675
2676<h5>Semantics:</h5>
2677
2678<p>
2679The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2680the return address of the specified call frame, or zero if it cannot be
2681identified. The value returned by this intrinsic is likely to be incorrect or 0
2682for arguments other than zero, so it should only be used for debugging purposes.
2683</p>
2684
2685<p>
2686Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]2687aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2688source-language caller.
2689</p>
2690</div>
2691
2692
2693<!-- _______________________________________________________________________ -->
2694<div class="doc_subsubsection">
2695 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2696</div>
2697
2698<div class="doc_text">
2699
2700<h5>Syntax:</h5>
2701<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2702 declare void* %llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2703</pre>
2704
2705<h5>Overview:</h5>
2706
2707<p>
2708The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2709pointer value for the specified stack frame.
2710</p>
2711
2712<h5>Arguments:</h5>
2713
2714<p>
2715The argument to this intrinsic indicates which function to return the frame
2716pointer for. Zero indicates the calling function, one indicates its caller,
2717etc. The argument is <b>required</b> to be a constant integer value.
2718</p>
2719
2720<h5>Semantics:</h5>
2721
2722<p>
2723The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2724the frame address of the specified call frame, or zero if it cannot be
2725identified. The value returned by this intrinsic is likely to be incorrect or 0
2726for arguments other than zero, so it should only be used for debugging purposes.
2727</p>
2728
2729<p>
2730Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]2731aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2732source-language caller.
2733</p>
2734</div>
2735
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2736<!-- _______________________________________________________________________ -->
2737<div class="doc_subsubsection">
2738 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
2739</div>
2740
2741<div class="doc_text">
2742
2743<h5>Syntax:</h5>
2744<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2745 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
2746 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2747</pre>
2748
2749<h5>Overview:</h5>
2750
2751
2752<p>
2753The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2754a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
2755no
2756effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]2757characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2758</p>
2759
2760<h5>Arguments:</h5>
2761
2762<p>
2763<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
2764determining if the fetch should be for a read (0) or write (1), and
2765<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]2766locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2767<tt>locality</tt> arguments must be constant integers.
2768</p>
2769
2770<h5>Semantics:</h5>
2771
2772<p>
2773This intrinsic does not modify the behavior of the program. In particular,
2774prefetches cannot trap and do not produce a value. On targets that support this
2775intrinsic, the prefetch can provide hints to the processor cache for better
2776performance.
2777</p>
2778
2779</div>
2780
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2781<!-- _______________________________________________________________________ -->
2782<div class="doc_subsubsection">
2783 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
2784</div>
2785
2786<div class="doc_text">
2787
2788<h5>Syntax:</h5>
2789<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2790 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2791</pre>
2792
2793<h5>Overview:</h5>
2794
2795
2796<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2797The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
2798(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2799code to simulators and other tools. The method is target specific, but it is
2800expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]2801The marker makes no guarantees that it will remain with any specific instruction
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2802after optimizations. It is possible that the presense of a marker will inhibit
2803optimizations. The intended use is to be inserted after optmizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2804correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2805</p>
2806
2807<h5>Arguments:</h5>
2808
2809<p>
2810<tt>id</tt> is a numerical id identifying the marker.
2811</p>
2812
2813<h5>Semantics:</h5>
2814
2815<p>
2816This intrinsic does not modify the behavior of the program. Backends that do not
2817support this intrinisic may ignore it.
2818</p>
2819
2820</div>
2821
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]2822<!-- _______________________________________________________________________ -->
2823<div class="doc_subsubsection">
2824 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
2825</div>
2826
2827<div class="doc_text">
2828
2829<h5>Syntax:</h5>
2830<pre>
2831 declare ulong %llvm.readcyclecounter( )
2832</pre>
2833
2834<h5>Overview:</h5>
2835
2836
2837<p>
2838The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
2839counter register (or similar low latency, high accuracy clocks) on those targets
2840that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
2841As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
2842should only be used for small timings.
2843</p>
2844
2845<h5>Semantics:</h5>
2846
2847<p>
2848When directly supported, reading the cycle counter should not modify any memory.
2849Implementations are allowed to either return a application specific value or a
2850system wide value. On backends without support, this is lowered to a constant 0.
2851</p>
2852
2853</div>
2854
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2855
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2856<!-- ======================================================================= -->
2857<div class="doc_subsection">
2858 <a name="int_os">Operating System Intrinsics</a>
2859</div>
2860
2861<div class="doc_text">
2862<p>
2863These intrinsics are provided by LLVM to support the implementation of
2864operating system level code.
2865</p>
2866
2867</div>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2868
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2869<!-- _______________________________________________________________________ -->
2870<div class="doc_subsubsection">
2871 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2872</div>
2873
2874<div class="doc_text">
2875
2876<h5>Syntax:</h5>
2877<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2878 declare &lt;integer type&gt; %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2879</pre>
2880
2881<h5>Overview:</h5>
2882
2883<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2884The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2885I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2886</p>
2887
2888<h5>Arguments:</h5>
2889
2890<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2891The argument to this intrinsic indicates the hardware I/O address from which
2892to read the data. The address is in the hardware I/O address namespace (as
2893opposed to being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2894</p>
2895
2896<h5>Semantics:</h5>
2897
2898<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2899The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2900specified by <i>address</i> and returns the value. The address and return
2901value must be integers, but the size is dependent upon the platform upon which
2902the program is code generated. For example, on x86, the address must be an
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2903unsigned 16-bit value, and the return value must be 8, 16, or 32 bits.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2904</p>
2905
2906</div>
2907
2908<!-- _______________________________________________________________________ -->
2909<div class="doc_subsubsection">
2910 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2911</div>
2912
2913<div class="doc_text">
2914
2915<h5>Syntax:</h5>
2916<pre>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]2917 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
2918 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
2919 &lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2920</pre>
2921
2922<h5>Overview:</h5>
2923
2924<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2925The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2926I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2927</p>
2928
2929<h5>Arguments:</h5>
2930
2931<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2932The first argument is the value to write to the I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2933</p>
2934
2935<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2936The second argument indicates the hardware I/O address to which data should be
2937written. The address is in the hardware I/O address namespace (as opposed to
2938being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2939</p>
2940
2941<h5>Semantics:</h5>
2942
2943<p>
2944The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2945specified by <i>address</i>. The address and value must be integers, but the
2946size is dependent upon the platform upon which the program is code generated.
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2947For example, on x86, the address must be an unsigned 16-bit value, and the
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2948value written must be 8, 16, or 32 bits in length.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2949</p>
2950
2951</div>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2952
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2953<!-- _______________________________________________________________________ -->
2954<div class="doc_subsubsection">
2955 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
2956</div>
2957
2958<div class="doc_text">
2959
2960<h5>Syntax:</h5>
2961<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2962 declare &lt;result&gt; %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2963</pre>
2964
2965<h5>Overview:</h5>
2966
2967<p>
2968The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
2969address.
2970</p>
2971
2972<h5>Arguments:</h5>
2973
2974<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2975The argument to this intrinsic is a pointer indicating the memory address from
2976which to read the data. The data must be a
2977<a href="#t_firstclass">first class</a> type.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2978</p>
2979
2980<h5>Semantics:</h5>
2981
2982<p>
2983The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2984location specified by <i>pointer</i> and returns the value. The argument must
2985be a pointer, and the return value must be a
2986<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2987may not support I/O on all first class types. For example, 32-bit processors
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2988may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2989</p>
2990
2991<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2992This intrinsic enforces an in-order memory model for llvm.readio and
2993llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2994scheduled processors may execute loads and stores out of order, re-ordering at
2995run time accesses to memory mapped I/O registers. Using these intrinsics
2996ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2997</p>
2998
2999</div>
3000
3001<!-- _______________________________________________________________________ -->
3002<div class="doc_subsubsection">
3003 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
3004</div>
3005
3006<div class="doc_text">
3007
3008<h5>Syntax:</h5>
3009<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3010 declare void %llvm.writeio (&lt;ty1&gt; &lt;value&gt;, &lt;ty2&gt; * &lt;pointer&gt;)
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3011</pre>
3012
3013<h5>Overview:</h5>
3014
3015<p>
3016The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
3017mapped I/O address.
3018</p>
3019
3020<h5>Arguments:</h5>
3021
3022<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3023The first argument is the value to write to the memory mapped I/O location.
3024The second argument is a pointer indicating the memory address to which the
3025data should be written.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3026</p>
3027
3028<h5>Semantics:</h5>
3029
3030<p>
3031The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3032I/O address specified by <i>pointer</i>. The value must be a
3033<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]3034may not support I/O on all first class types. For example, 32-bit processors
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3035may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3036</p>
3037
3038<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3039This intrinsic enforces an in-order memory model for llvm.readio and
3040llvm.writeio calls on machines that use dynamic scheduling. Dynamically
3041scheduled processors may execute loads and stores out of order, re-ordering at
3042run time accesses to memory mapped I/O registers. Using these intrinsics
3043ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3044</p>
3045
3046</div>
3047
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3048<!-- ======================================================================= -->
3049<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3050 <a name="int_libc">Standard C Library Intrinsics</a>
3051</div>
3052
3053<div class="doc_text">
3054<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3055LLVM provides intrinsics for a few important standard C library functions.
3056These intrinsics allow source-language front-ends to pass information about the
3057alignment of the pointer arguments to the code generator, providing opportunity
3058for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3059</p>
3060
3061</div>
3062
3063<!-- _______________________________________________________________________ -->
3064<div class="doc_subsubsection">
3065 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
3066</div>
3067
3068<div class="doc_text">
3069
3070<h5>Syntax:</h5>
3071<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3072 declare void %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3073 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3074</pre>
3075
3076<h5>Overview:</h5>
3077
3078<p>
3079The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3080location to the destination location.
3081</p>
3082
3083<p>
3084Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
3085does not return a value, and takes an extra alignment argument.
3086</p>
3087
3088<h5>Arguments:</h5>
3089
3090<p>
3091The first argument is a pointer to the destination, the second is a pointer to
3092the source. The third argument is an (arbitrarily sized) integer argument
3093specifying the number of bytes to copy, and the fourth argument is the alignment
3094of the source and destination locations.
3095</p>
3096
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]3097<p>
3098If the call to this intrinisic has an alignment value that is not 0 or 1, then
3099the caller guarantees that the size of the copy is a multiple of the alignment
3100and that both the source and destination pointers are aligned to that boundary.
3101</p>
3102
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3103<h5>Semantics:</h5>
3104
3105<p>
3106The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3107location to the destination location, which are not allowed to overlap. It
3108copies "len" bytes of memory over. If the argument is known to be aligned to
3109some boundary, this can be specified as the fourth argument, otherwise it should
3110be set to 0 or 1.
3111</p>
3112</div>
3113
3114
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3115<!-- _______________________________________________________________________ -->
3116<div class="doc_subsubsection">
3117 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3118</div>
3119
3120<div class="doc_text">
3121
3122<h5>Syntax:</h5>
3123<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3124 declare void %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3125 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3126</pre>
3127
3128<h5>Overview:</h5>
3129
3130<p>
3131The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
3132location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
3133intrinsic but allows the two memory locations to overlap.
3134</p>
3135
3136<p>
3137Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
3138does not return a value, and takes an extra alignment argument.
3139</p>
3140
3141<h5>Arguments:</h5>
3142
3143<p>
3144The first argument is a pointer to the destination, the second is a pointer to
3145the source. The third argument is an (arbitrarily sized) integer argument
3146specifying the number of bytes to copy, and the fourth argument is the alignment
3147of the source and destination locations.
3148</p>
3149
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]3150<p>
3151If the call to this intrinisic has an alignment value that is not 0 or 1, then
3152the caller guarantees that the size of the copy is a multiple of the alignment
3153and that both the source and destination pointers are aligned to that boundary.
3154</p>
3155
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3156<h5>Semantics:</h5>
3157
3158<p>
3159The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
3160location to the destination location, which may overlap. It
3161copies "len" bytes of memory over. If the argument is known to be aligned to
3162some boundary, this can be specified as the fourth argument, otherwise it should
3163be set to 0 or 1.
3164</p>
3165</div>
3166
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3167
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3168<!-- _______________________________________________________________________ -->
3169<div class="doc_subsubsection">
3170 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
3171</div>
3172
3173<div class="doc_text">
3174
3175<h5>Syntax:</h5>
3176<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3177 declare void %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3178 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3179</pre>
3180
3181<h5>Overview:</h5>
3182
3183<p>
3184The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
3185byte value.
3186</p>
3187
3188<p>
3189Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3190does not return a value, and takes an extra alignment argument.
3191</p>
3192
3193<h5>Arguments:</h5>
3194
3195<p>
3196The first argument is a pointer to the destination to fill, the second is the
3197byte value to fill it with, the third argument is an (arbitrarily sized) integer
3198argument specifying the number of bytes to fill, and the fourth argument is the
3199known alignment of destination location.
3200</p>
3201
3202<p>
3203If the call to this intrinisic has an alignment value that is not 0 or 1, then
3204the caller guarantees that the size of the copy is a multiple of the alignment
3205and that the destination pointer is aligned to that boundary.
3206</p>
3207
3208<h5>Semantics:</h5>
3209
3210<p>
3211The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
3212destination location. If the argument is known to be aligned to some boundary,
3213this can be specified as the fourth argument, otherwise it should be set to 0 or
32141.
3215</p>
3216</div>
3217
3218
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]3219<!-- _______________________________________________________________________ -->
3220<div class="doc_subsubsection">
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]3221 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
3222</div>
3223
3224<div class="doc_text">
3225
3226<h5>Syntax:</h5>
3227<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3228 declare bool %llvm.isunordered(&lt;float or double&gt; Val1, &lt;float or double&gt; Val2)
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]3229</pre>
3230
3231<h5>Overview:</h5>
3232
3233<p>
3234The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
3235specified floating point values is a NAN.
3236</p>
3237
3238<h5>Arguments:</h5>
3239
3240<p>
3241The arguments are floating point numbers of the same type.
3242</p>
3243
3244<h5>Semantics:</h5>
3245
3246<p>
3247If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3248false.
3249</p>
3250</div>
3251
3252
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]3253<!-- _______________________________________________________________________ -->
3254<div class="doc_subsubsection">
3255 <a name="i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a>
3256</div>
3257
3258<div class="doc_text">
3259
3260<h5>Syntax:</h5>
3261<pre>
3262 declare &lt;float or double&gt; %llvm.sqrt(&lt;float or double&gt; Val)
3263</pre>
3264
3265<h5>Overview:</h5>
3266
3267<p>
3268The '<tt>llvm.sqrt</tt>' intrinsic returns the sqrt of the specified operand,
3269returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
3270<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
3271negative numbers (which allows for better optimization).
3272</p>
3273
3274<h5>Arguments:</h5>
3275
3276<p>
3277The argument and return value are floating point numbers of the same type.
3278</p>
3279
3280<h5>Semantics:</h5>
3281
3282<p>
3283This function returns the sqrt of the specified operand if it is a positive
3284floating point number.
3285</p>
3286</div>
3287
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3288<!-- ======================================================================= -->
3289<div class="doc_subsection">
3290 <a name="int_count">Bit Counting Intrinsics</a>
3291</div>
3292
3293<div class="doc_text">
3294<p>
3295LLVM provides intrinsics for a few important bit counting operations.
3296These allow efficient code generation for some algorithms.
3297</p>
3298
3299</div>
3300
3301<!-- _______________________________________________________________________ -->
3302<div class="doc_subsubsection">
3303 <a name="int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic</a>
3304</div>
3305
3306<div class="doc_text">
3307
3308<h5>Syntax:</h5>
3309<pre>
3310 declare int %llvm.ctpop(int &lt;src&gt;)
3311
3312</pre>
3313
3314<h5>Overview:</h5>
3315
3316<p>
3317The '<tt>llvm.ctpop</tt>' intrinsic counts the number of ones in a variable.
3318</p>
3319
3320<h5>Arguments:</h5>
3321
3322<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3323The only argument is the value to be counted. The argument may be of any
3324integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3325</p>
3326
3327<h5>Semantics:</h5>
3328
3329<p>
3330The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3331</p>
3332</div>
3333
3334<!-- _______________________________________________________________________ -->
3335<div class="doc_subsubsection">
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3336 <a name="int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic</a>
3337</div>
3338
3339<div class="doc_text">
3340
3341<h5>Syntax:</h5>
3342<pre>
3343 declare int %llvm.ctlz(int &lt;src&gt;)
3344
3345</pre>
3346
3347<h5>Overview:</h5>
3348
3349<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3350The '<tt>llvm.ctlz</tt>' intrinsic counts the number of leading zeros in a
3351variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3352</p>
3353
3354<h5>Arguments:</h5>
3355
3356<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3357The only argument is the value to be counted. The argument may be of any
3358integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3359</p>
3360
3361<h5>Semantics:</h5>
3362
3363<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3364The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
3365in a variable. If the src == 0 then the result is the size in bits of the type
3366of src. For example, <tt>llvm.cttz(int 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3367</p>
3368</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]3369
3370
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3371
3372<!-- _______________________________________________________________________ -->
3373<div class="doc_subsubsection">
3374 <a name="int_cttz">'<tt>llvm.cttz</tt>' Intrinsic</a>
3375</div>
3376
3377<div class="doc_text">
3378
3379<h5>Syntax:</h5>
3380<pre>
3381 declare int %llvm.cttz(int &lt;src&gt;)
3382
3383</pre>
3384
3385<h5>Overview:</h5>
3386
3387<p>
3388The '<tt>llvm.cttz</tt>' intrinsic counts the number of trailing zeros.
3389</p>
3390
3391<h5>Arguments:</h5>
3392
3393<p>
3394The only argument is the value to be counted. The argument may be of any
3395integer type. The return type must match the argument type.
3396</p>
3397
3398<h5>Semantics:</h5>
3399
3400<p>
3401The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
3402in a variable. If the src == 0 then the result is the size in bits of the type
3403of src. For example, <tt>llvm.cttz(2) = 1</tt>.
3404</p>
3405</div>
3406
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3407<!-- ======================================================================= -->
3408<div class="doc_subsection">
3409 <a name="int_debugger">Debugger Intrinsics</a>
3410</div>
3411
3412<div class="doc_text">
3413<p>
3414The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3415are described in the <a
3416href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3417Debugging</a> document.
3418</p>
3419</div>
3420
3421
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3422<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3423<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]3424<address>
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3429
3430 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
3431 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
3432 Last modified: $Date$
3433</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3434</body>
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