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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 2cbdc45f351aaccd63e612897cd57792a7f6360a / . / 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>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]131 </ol>
132 </li>
133 <li><a href="#int_os">Operating System Intrinsics</a>
134 <ol>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]135 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
136 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]137 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
138 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]139 </ol>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]140 <li><a href="#int_libc">Standard C Library Intrinsics</a>
141 <ol>
142 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]143 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]144 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos96853722004-06-12 19:19:14 +0000[diff] [blame]145 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]146 <li><a href="#i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a></li>
147
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]148 </ol>
149 </li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]150 <li><a href="#int_count">Bit counting Intrinsics</a>
151 <ol>
152 <li><a href="#int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]153 <li><a href="#int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic </a></li>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]154 <li><a href="#int_cttz">'<tt>llvm.cttz</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]155 </ol>
156 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]157 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]158 </ol>
159 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]160</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]161
162<div class="doc_author">
163 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
164 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]165</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]166
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]167<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]168<div class="doc_section"> <a name="abstract">Abstract </a></div>
169<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]170
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]171<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]172<p>This document is a reference manual for the LLVM assembly language.
173LLVM is an SSA based representation that provides type safety,
174low-level operations, flexibility, and the capability of representing
175'all' high-level languages cleanly. It is the common code
176representation used throughout all phases of the LLVM compilation
177strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]178</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]179
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]180<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]181<div class="doc_section"> <a name="introduction">Introduction</a> </div>
182<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]183
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]184<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]185
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]186<p>The LLVM code representation is designed to be used in three
187different forms: as an in-memory compiler IR, as an on-disk bytecode
188representation (suitable for fast loading by a Just-In-Time compiler),
189and as a human readable assembly language representation. This allows
190LLVM to provide a powerful intermediate representation for efficient
191compiler transformations and analysis, while providing a natural means
192to debug and visualize the transformations. The three different forms
193of LLVM are all equivalent. This document describes the human readable
194representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]195
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]196<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]197while being expressive, typed, and extensible at the same time. It
198aims to be a "universal IR" of sorts, by being at a low enough level
199that high-level ideas may be cleanly mapped to it (similar to how
200microprocessors are "universal IR's", allowing many source languages to
201be mapped to them). By providing type information, LLVM can be used as
202the target of optimizations: for example, through pointer analysis, it
203can be proven that a C automatic variable is never accessed outside of
204the current function... allowing it to be promoted to a simple SSA
205value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]206
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]207</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]208
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]209<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]210<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]211
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]212<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]213
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]214<p>It is important to note that this document describes 'well formed'
215LLVM assembly language. There is a difference between what the parser
216accepts and what is considered 'well formed'. For example, the
217following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]218
219<pre>
220 %x = <a href="#i_add">add</a> int 1, %x
221</pre>
222
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]223<p>...because the definition of <tt>%x</tt> does not dominate all of
224its uses. The LLVM infrastructure provides a verification pass that may
225be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]226automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]227the optimizer before it outputs bytecode. The violations pointed out
228by the verifier pass indicate bugs in transformation passes or input to
229the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]230
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]231<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]232
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]233<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]234<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]235<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]236
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]237<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]238
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]239<p>LLVM uses three different forms of identifiers, for different
240purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]241
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]242<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]243 <li>Named values are represented as a string of characters with a '%' prefix.
244 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
245 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
246 Identifiers which require other characters in their names can be surrounded
247 with quotes. In this way, anything except a <tt>"</tt> character can be used
248 in a name.</li>
249
250 <li>Unnamed values are represented as an unsigned numeric value with a '%'
251 prefix. For example, %12, %2, %44.</li>
252
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]253 <li>Constants, which are described in a <a href="#constants">section about
254 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]255</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]256
257<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
258don't need to worry about name clashes with reserved words, and the set of
259reserved words may be expanded in the future without penalty. Additionally,
260unnamed identifiers allow a compiler to quickly come up with a temporary
261variable without having to avoid symbol table conflicts.</p>
262
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]263<p>Reserved words in LLVM are very similar to reserved words in other
264languages. There are keywords for different opcodes ('<tt><a
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]265href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
266href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
267href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
268and others. These reserved words cannot conflict with variable names, because
269none of them start with a '%' character.</p>
270
271<p>Here is an example of LLVM code to multiply the integer variable
272'<tt>%X</tt>' by 8:</p>
273
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]274<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]275
276<pre>
277 %result = <a href="#i_mul">mul</a> uint %X, 8
278</pre>
279
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]280<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]281
282<pre>
283 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
284</pre>
285
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]286<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]287
288<pre>
289 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
290 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
291 %result = <a href="#i_add">add</a> uint %1, %1
292</pre>
293
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]294<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
295important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]296
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]297<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]298
299 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
300 line.</li>
301
302 <li>Unnamed temporaries are created when the result of a computation is not
303 assigned to a named value.</li>
304
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]305 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]306
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]307</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]308
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]309<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]310demonstrating instructions, we will follow an instruction with a comment that
311defines the type and name of value produced. Comments are shown in italic
312text.</p>
313
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]314</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]315
316<!-- *********************************************************************** -->
317<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
318<!-- *********************************************************************** -->
319
320<!-- ======================================================================= -->
321<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
322</div>
323
324<div class="doc_text">
325
326<p>LLVM programs are composed of "Module"s, each of which is a
327translation unit of the input programs. Each module consists of
328functions, global variables, and symbol table entries. Modules may be
329combined together with the LLVM linker, which merges function (and
330global variable) definitions, resolves forward declarations, and merges
331symbol table entries. Here is an example of the "hello world" module:</p>
332
333<pre><i>; Declare the string constant as a global constant...</i>
334<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
335 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
336
337<i>; External declaration of the puts function</i>
338<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
339
340<i>; Definition of main function</i>
341int %main() { <i>; int()* </i>
342 <i>; Convert [13x sbyte]* to sbyte *...</i>
343 %cast210 = <a
344 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
345
346 <i>; Call puts function to write out the string to stdout...</i>
347 <a
348 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
349 <a
350 href="#i_ret">ret</a> int 0<br>}<br></pre>
351
352<p>This example is made up of a <a href="#globalvars">global variable</a>
353named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
354function, and a <a href="#functionstructure">function definition</a>
355for "<tt>main</tt>".</p>
356
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]357<p>In general, a module is made up of a list of global values,
358where both functions and global variables are global values. Global values are
359represented by a pointer to a memory location (in this case, a pointer to an
360array of char, and a pointer to a function), and have one of the following <a
361href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]362
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]363</div>
364
365<!-- ======================================================================= -->
366<div class="doc_subsection">
367 <a name="linkage">Linkage Types</a>
368</div>
369
370<div class="doc_text">
371
372<p>
373All Global Variables and Functions have one of the following types of linkage:
374</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]375
376<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]377
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]378 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]379
380 <dd>Global values with internal linkage are only directly accessible by
381 objects in the current module. In particular, linking code into a module with
382 an internal global value may cause the internal to be renamed as necessary to
383 avoid collisions. Because the symbol is internal to the module, all
384 references can be updated. This corresponds to the notion of the
385 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]386 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]387
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]388 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]389
390 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
391 the twist that linking together two modules defining the same
392 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
393 is typically used to implement inline functions. Unreferenced
394 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]395 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]396
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]397 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]398
399 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
400 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
401 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]402 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]403
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]404 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]405
406 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
407 pointer to array type. When two global variables with appending linkage are
408 linked together, the two global arrays are appended together. This is the
409 LLVM, typesafe, equivalent of having the system linker append together
410 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]411 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]412
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]413 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]414
415 <dd>If none of the above identifiers are used, the global is externally
416 visible, meaning that it participates in linkage and can be used to resolve
417 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]418 </dd>
419</dl>
420
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]421<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
422variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
423variable and was linked with this one, one of the two would be renamed,
424preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
425external (i.e., lacking any linkage declarations), they are accessible
426outside of the current module. It is illegal for a function <i>declaration</i>
427to have any linkage type other than "externally visible".</a></p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]428
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]429</div>
430
431<!-- ======================================================================= -->
432<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]433 <a name="callingconv">Calling Conventions</a>
434</div>
435
436<div class="doc_text">
437
438<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
439and <a href="#i_invoke">invokes</a> can all have an optional calling convention
440specified for the call. The calling convention of any pair of dynamic
441caller/callee must match, or the behavior of the program is undefined. The
442following calling conventions are supported by LLVM, and more may be added in
443the future:</p>
444
445<dl>
446 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
447
448 <dd>This calling convention (the default if no other calling convention is
449 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]450 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]451 prototype and implemented declaration of the function (as does normal C).
452 </dd>
453
454 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
455
456 <dd>This calling convention attempts to make calls as fast as possible
457 (e.g. by passing things in registers). This calling convention allows the
458 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]459 without having to conform to an externally specified ABI. Implementations of
460 this convention should allow arbitrary tail call optimization to be supported.
461 This calling convention does not support varargs and requires the prototype of
462 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]463 </dd>
464
465 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
466
467 <dd>This calling convention attempts to make code in the caller as efficient
468 as possible under the assumption that the call is not commonly executed. As
469 such, these calls often preserve all registers so that the call does not break
470 any live ranges in the caller side. This calling convention does not support
471 varargs and requires the prototype of all callees to exactly match the
472 prototype of the function definition.
473 </dd>
474
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]475 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]476
477 <dd>Any calling convention may be specified by number, allowing
478 target-specific calling conventions to be used. Target specific calling
479 conventions start at 64.
480 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]481</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]482
483<p>More calling conventions can be added/defined on an as-needed basis, to
484support pascal conventions or any other well-known target-independent
485convention.</p>
486
487</div>
488
489<!-- ======================================================================= -->
490<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]491 <a name="globalvars">Global Variables</a>
492</div>
493
494<div class="doc_text">
495
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]496<p>Global variables define regions of memory allocated at compilation time
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]497instead of run-time. Global variables may optionally be initialized, and may
498have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]499variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]500contents of the variable will <b>never</b> be modified (enabling better
501optimization, allowing the global data to be placed in the read-only section of
502an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]503cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]504
505<p>
506LLVM explicitly allows <em>declarations</em> of global variables to be marked
507constant, even if the final definition of the global is not. This capability
508can be used to enable slightly better optimization of the program, but requires
509the language definition to guarantee that optimizations based on the
510'constantness' are valid for the translation units that do not include the
511definition.
512</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]513
514<p>As SSA values, global variables define pointer values that are in
515scope (i.e. they dominate) all basic blocks in the program. Global
516variables always define a pointer to their "content" type because they
517describe a region of memory, and all memory objects in LLVM are
518accessed through pointers.</p>
519
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]520<p>An explicit alignment may be specified for a global. If not present, or if
521the alignment is set to zero, the alignment of the global is set by the target
522to whatever it feels convenient. If an explicit alignment is specified, the
523global is forced to have at least that much alignment. All alignments must be
524a power of 2.</p>
525
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]526</div>
527
528
529<!-- ======================================================================= -->
530<div class="doc_subsection">
531 <a name="functionstructure">Functions</a>
532</div>
533
534<div class="doc_text">
535
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]536<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
537type</a>, an optional <a href="#callingconv">calling convention</a>, a return
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]538type, a function name, a (possibly empty) argument list, an optional alignment,
539an opening curly brace,
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]540a list of basic blocks, and a closing curly brace. LLVM function declarations
541are defined with the "<tt>declare</tt>" keyword, an optional <a
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]542href="#callingconv">calling convention</a>, a return type, a function name,
543a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]544
545<p>A function definition contains a list of basic blocks, forming the CFG for
546the function. Each basic block may optionally start with a label (giving the
547basic block a symbol table entry), contains a list of instructions, and ends
548with a <a href="#terminators">terminator</a> instruction (such as a branch or
549function return).</p>
550
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]551<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]552executed on entrance to the function, and it is not allowed to have predecessor
553basic blocks (i.e. there can not be any branches to the entry block of a
554function). Because the block can have no predecessors, it also cannot have any
555<a href="#i_phi">PHI nodes</a>.</p>
556
557<p>LLVM functions are identified by their name and type signature. Hence, two
558functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]559considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]560appropriately.</p>
561
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]562<p>An explicit alignment may be specified for a function. If not present, or if
563the alignment is set to zero, the alignment of the function is set by the target
564to whatever it feels convenient. If an explicit alignment is specified, the
565function is forced to have at least that much alignment. All alignments must be
566a power of 2.</p>
567
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]568</div>
569
570
571
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]572<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]573<div class="doc_section"> <a name="typesystem">Type System</a> </div>
574<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]575
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]576<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]577
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]578<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]579intermediate representation. Being typed enables a number of
580optimizations to be performed on the IR directly, without having to do
581extra analyses on the side before the transformation. A strong type
582system makes it easier to read the generated code and enables novel
583analyses and transformations that are not feasible to perform on normal
584three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]585
586</div>
587
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]588<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]589<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]590<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]591<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]592system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]593
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]594<table class="layout">
595 <tr class="layout">
596 <td class="left">
597 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]598 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]599 <tr><th>Type</th><th>Description</th></tr>
600 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]601 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
602 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
603 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
604 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
605 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]606 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]607 </tbody>
608 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]609 </td>
610 <td class="right">
611 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]612 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]613 <tr><th>Type</th><th>Description</th></tr>
614 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]615 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
616 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
617 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
618 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
619 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]620 </tbody>
621 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]622 </td>
623 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]624</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]625</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]626
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]627<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]628<div class="doc_subsubsection"> <a name="t_classifications">Type
629Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]630<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]631<p>These different primitive types fall into a few useful
632classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]633
634<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]635 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]636 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]637 <tr>
638 <td><a name="t_signed">signed</a></td>
639 <td><tt>sbyte, short, int, long, float, double</tt></td>
640 </tr>
641 <tr>
642 <td><a name="t_unsigned">unsigned</a></td>
643 <td><tt>ubyte, ushort, uint, ulong</tt></td>
644 </tr>
645 <tr>
646 <td><a name="t_integer">integer</a></td>
647 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
648 </tr>
649 <tr>
650 <td><a name="t_integral">integral</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]651 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
652 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]653 </tr>
654 <tr>
655 <td><a name="t_floating">floating point</a></td>
656 <td><tt>float, double</tt></td>
657 </tr>
658 <tr>
659 <td><a name="t_firstclass">first class</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]660 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
661 float, double, <a href="#t_pointer">pointer</a>,
662 <a href="#t_packed">packed</a></tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]663 </tr>
664 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]665</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]666
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]667<p>The <a href="#t_firstclass">first class</a> types are perhaps the
668most important. Values of these types are the only ones which can be
669produced by instructions, passed as arguments, or used as operands to
670instructions. This means that all structures and arrays must be
671manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]672</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]673
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]674<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]675<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]676
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]677<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]678
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]679<p>The real power in LLVM comes from the derived types in the system.
680This is what allows a programmer to represent arrays, functions,
681pointers, and other useful types. Note that these derived types may be
682recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]683
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]684</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]685
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]686<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]687<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]688
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]689<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]690
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]691<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]692
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]693<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]694sequentially in memory. The array type requires a size (number of
695elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]696
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]697<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]698
699<pre>
700 [&lt;# elements&gt; x &lt;elementtype&gt;]
701</pre>
702
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]703<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]704be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]705
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]706<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]707<table class="layout">
708 <tr class="layout">
709 <td class="left">
710 <tt>[40 x int ]</tt><br/>
711 <tt>[41 x int ]</tt><br/>
712 <tt>[40 x uint]</tt><br/>
713 </td>
714 <td class="left">
715 Array of 40 integer values.<br/>
716 Array of 41 integer values.<br/>
717 Array of 40 unsigned integer values.<br/>
718 </td>
719 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]720</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]721<p>Here are some examples of multidimensional arrays:</p>
722<table class="layout">
723 <tr class="layout">
724 <td class="left">
725 <tt>[3 x [4 x int]]</tt><br/>
726 <tt>[12 x [10 x float]]</tt><br/>
727 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
728 </td>
729 <td class="left">
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]730 3x4 array of integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]731 12x10 array of single precision floating point values.<br/>
732 2x3x4 array of unsigned integer values.<br/>
733 </td>
734 </tr>
735</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]736
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]737<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
738length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]739LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
740As a special case, however, zero length arrays are recognized to be variable
741length. This allows implementation of 'pascal style arrays' with the LLVM
742type "{ int, [0 x float]}", for example.</p>
743
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]744</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]745
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]746<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]747<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]748<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]749<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]750<p>The function type can be thought of as a function signature. It
751consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]752Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]753(which are structures of pointers to functions), for indirect function
754calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]755<p>
756The return type of a function type cannot be an aggregate type.
757</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]758<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]759<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]760<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]761specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]762which indicates that the function takes a variable number of arguments.
763Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]764 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]765<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]766<table class="layout">
767 <tr class="layout">
768 <td class="left">
769 <tt>int (int)</tt> <br/>
770 <tt>float (int, int *) *</tt><br/>
771 <tt>int (sbyte *, ...)</tt><br/>
772 </td>
773 <td class="left">
774 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
775 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]776 <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]777 returning <tt>float</tt>.<br/>
778 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
779 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
780 the signature for <tt>printf</tt> in LLVM.<br/>
781 </td>
782 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]783</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]784
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]785</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]786<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]787<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]788<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]789<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]790<p>The structure type is used to represent a collection of data members
791together in memory. The packing of the field types is defined to match
792the ABI of the underlying processor. The elements of a structure may
793be any type that has a size.</p>
794<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
795and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
796field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
797instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]798<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]799<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]800<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]801<table class="layout">
802 <tr class="layout">
803 <td class="left">
804 <tt>{ int, int, int }</tt><br/>
805 <tt>{ float, int (int) * }</tt><br/>
806 </td>
807 <td class="left">
808 a triple of three <tt>int</tt> values<br/>
809 A pair, where the first element is a <tt>float</tt> and the second element
810 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
811 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
812 </td>
813 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]814</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]815</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]816
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]817<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]818<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]819<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]820<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]821<p>As in many languages, the pointer type represents a pointer or
822reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]823<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]824<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]825<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]826<table class="layout">
827 <tr class="layout">
828 <td class="left">
829 <tt>[4x int]*</tt><br/>
830 <tt>int (int *) *</tt><br/>
831 </td>
832 <td class="left">
833 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
834 four <tt>int</tt> values<br/>
835 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattnera977c482005-02-19 02:22:14 +0000[diff] [blame]836 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]837 <tt>int</tt>.<br/>
838 </td>
839 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]840</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]841</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]842
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]843<!-- _______________________________________________________________________ -->
844<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]845<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]846
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]847<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]848
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]849<p>A packed type is a simple derived type that represents a vector
850of elements. Packed types are used when multiple primitive data
851are operated in parallel using a single instruction (SIMD).
852A packed type requires a size (number of
853elements) and an underlying primitive data type. Packed types are
854considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]855
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]856<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]857
858<pre>
859 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
860</pre>
861
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]862<p>The number of elements is a constant integer value; elementtype may
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]863be any integral or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]864
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]865<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]866
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]867<table class="layout">
868 <tr class="layout">
869 <td class="left">
870 <tt>&lt;4 x int&gt;</tt><br/>
871 <tt>&lt;8 x float&gt;</tt><br/>
872 <tt>&lt;2 x uint&gt;</tt><br/>
873 </td>
874 <td class="left">
875 Packed vector of 4 integer values.<br/>
876 Packed vector of 8 floating-point values.<br/>
877 Packed vector of 2 unsigned integer values.<br/>
878 </td>
879 </tr>
880</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]881</div>
882
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]883<!-- _______________________________________________________________________ -->
884<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
885<div class="doc_text">
886
887<h5>Overview:</h5>
888
889<p>Opaque types are used to represent unknown types in the system. This
890corresponds (for example) to the C notion of a foward declared structure type.
891In LLVM, opaque types can eventually be resolved to any type (not just a
892structure type).</p>
893
894<h5>Syntax:</h5>
895
896<pre>
897 opaque
898</pre>
899
900<h5>Examples:</h5>
901
902<table class="layout">
903 <tr class="layout">
904 <td class="left">
905 <tt>opaque</tt>
906 </td>
907 <td class="left">
908 An opaque type.<br/>
909 </td>
910 </tr>
911</table>
912</div>
913
914
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]915<!-- *********************************************************************** -->
916<div class="doc_section"> <a name="constants">Constants</a> </div>
917<!-- *********************************************************************** -->
918
919<div class="doc_text">
920
921<p>LLVM has several different basic types of constants. This section describes
922them all and their syntax.</p>
923
924</div>
925
926<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]927<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]928
929<div class="doc_text">
930
931<dl>
932 <dt><b>Boolean constants</b></dt>
933
934 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
935 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
936 </dd>
937
938 <dt><b>Integer constants</b></dt>
939
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]940 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]941 href="#t_integer">integer</a> type. Negative numbers may be used with signed
942 integer types.
943 </dd>
944
945 <dt><b>Floating point constants</b></dt>
946
947 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
948 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]949 notation (see below). Floating point constants must have a <a
950 href="#t_floating">floating point</a> type. </dd>
951
952 <dt><b>Null pointer constants</b></dt>
953
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]954 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]955 and must be of <a href="#t_pointer">pointer type</a>.</dd>
956
957</dl>
958
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]959<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]960of floating point constants. For example, the form '<tt>double
9610x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
9624.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]963(and the only time that they are generated by the disassembler) is when a
964floating point constant must be emitted but it cannot be represented as a
965decimal floating point number. For example, NaN's, infinities, and other
966special values are represented in their IEEE hexadecimal format so that
967assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]968
969</div>
970
971<!-- ======================================================================= -->
972<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
973</div>
974
975<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]976<p>Aggregate constants arise from aggregation of simple constants
977and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]978
979<dl>
980 <dt><b>Structure constants</b></dt>
981
982 <dd>Structure constants are represented with notation similar to structure
983 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]984 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
985 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
986 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]987 types of elements must match those specified by the type.
988 </dd>
989
990 <dt><b>Array constants</b></dt>
991
992 <dd>Array constants are represented with notation similar to array type
993 definitions (a comma separated list of elements, surrounded by square brackets
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]994 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]995 constants must have <a href="#t_array">array type</a>, and the number and
996 types of elements must match those specified by the type.
997 </dd>
998
999 <dt><b>Packed constants</b></dt>
1000
1001 <dd>Packed constants are represented with notation similar to packed type
1002 definitions (a comma separated list of elements, surrounded by
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1003 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]1004 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
1005 href="#t_packed">packed type</a>, and the number and types of elements must
1006 match those specified by the type.
1007 </dd>
1008
1009 <dt><b>Zero initialization</b></dt>
1010
1011 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1012 value to zero of <em>any</em> type, including scalar and aggregate types.
1013 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]1014 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1015 initializers.
1016 </dd>
1017</dl>
1018
1019</div>
1020
1021<!-- ======================================================================= -->
1022<div class="doc_subsection">
1023 <a name="globalconstants">Global Variable and Function Addresses</a>
1024</div>
1025
1026<div class="doc_text">
1027
1028<p>The addresses of <a href="#globalvars">global variables</a> and <a
1029href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1030constants. These constants are explicitly referenced when the <a
1031href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1032href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1033file:</p>
1034
1035<pre>
1036 %X = global int 17
1037 %Y = global int 42
1038 %Z = global [2 x int*] [ int* %X, int* %Y ]
1039</pre>
1040
1041</div>
1042
1043<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1044<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1045<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1046 <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]1047 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1048 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1049
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1050 <p>Undefined values indicate to the compiler that the program is well defined
1051 no matter what value is used, giving the compiler more freedom to optimize.
1052 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1053</div>
1054
1055<!-- ======================================================================= -->
1056<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1057</div>
1058
1059<div class="doc_text">
1060
1061<p>Constant expressions are used to allow expressions involving other constants
1062to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1063href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1064that does not have side effects (e.g. load and call are not supported). The
1065following is the syntax for constant expressions:</p>
1066
1067<dl>
1068 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1069
1070 <dd>Cast a constant to another type.</dd>
1071
1072 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1073
1074 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1075 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1076 instruction, the index list may have zero or more indexes, which are required
1077 to make sense for the type of "CSTPTR".</dd>
1078
1079 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1080
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1081 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1082 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1083 binary</a> operations. The constraints on operands are the same as those for
1084 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1085 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1086</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1087</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1088
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1089<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1090<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1091<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1092
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1093<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1094
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1095<p>The LLVM instruction set consists of several different
1096classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1097instructions</a>, <a href="#binaryops">binary instructions</a>,
1098<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1099 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1100instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1101
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1102</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1103
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1104<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1105<div class="doc_subsection"> <a name="terminators">Terminator
1106Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1107
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1108<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1109
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1110<p>As mentioned <a href="#functionstructure">previously</a>, every
1111basic block in a program ends with a "Terminator" instruction, which
1112indicates which block should be executed after the current block is
1113finished. These terminator instructions typically yield a '<tt>void</tt>'
1114value: they produce control flow, not values (the one exception being
1115the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1116<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1117 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1118instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1119the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1120 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1121 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1122
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1123</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1124
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1125<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1126<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1127Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1128<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1129<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1130<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]1131 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1132</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1133<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1134<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1135value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1136<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1137returns a value and then causes control flow, and one that just causes
1138control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1139<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1140<p>The '<tt>ret</tt>' instruction may return any '<a
1141 href="#t_firstclass">first class</a>' type. Notice that a function is
1142not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1143instruction inside of the function that returns a value that does not
1144match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1145<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1146<p>When the '<tt>ret</tt>' instruction is executed, control flow
1147returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1148 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1149the instruction after the call. If the caller was an "<a
1150 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1151at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1152returns a value, that value shall set the call or invoke instruction's
1153return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1154<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1155<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1156 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1157</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1158</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1159<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1160<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1161<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1162<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1163<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]1164</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1165<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1166<p>The '<tt>br</tt>' instruction is used to cause control flow to
1167transfer to a different basic block in the current function. There are
1168two forms of this instruction, corresponding to a conditional branch
1169and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1170<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1171<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1172single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1173unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1174value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1175<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1176<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1177argument is evaluated. If the value is <tt>true</tt>, control flows
1178to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1179control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1180<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1181<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
1182 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]1183</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1184<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1185<div class="doc_subsubsection">
1186 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1187</div>
1188
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1189<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1190<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1191
1192<pre>
1193 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1194</pre>
1195
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1196<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1197
1198<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1199several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1200instruction, allowing a branch to occur to one of many possible
1201destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1202
1203
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1204<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1205
1206<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1207comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1208an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1209table is not allowed to contain duplicate constant entries.</p>
1210
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1211<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1212
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1213<p>The <tt>switch</tt> instruction specifies a table of values and
1214destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1215table is searched for the given value. If the value is found, control flow is
1216transfered to the corresponding destination; otherwise, control flow is
1217transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1218
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1219<h5>Implementation:</h5>
1220
1221<p>Depending on properties of the target machine and the particular
1222<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1223ways. For example, it could be generated as a series of chained conditional
1224branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1225
1226<h5>Example:</h5>
1227
1228<pre>
1229 <i>; Emulate a conditional br instruction</i>
1230 %Val = <a href="#i_cast">cast</a> bool %value to int
1231 switch int %Val, label %truedest [int 0, label %falsedest ]
1232
1233 <i>; Emulate an unconditional br instruction</i>
1234 switch uint 0, label %dest [ ]
1235
1236 <i>; Implement a jump table:</i>
1237 switch uint %val, label %otherwise [ uint 0, label %onzero
1238 uint 1, label %onone
1239 uint 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1240</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1241</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1242
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1243<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1244<div class="doc_subsubsection">
1245 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1246</div>
1247
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1248<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1249
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1250<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1251
1252<pre>
1253 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1254 to label &lt;normal label&gt; except label &lt;exception label&gt;
1255</pre>
1256
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1257<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1258
1259<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1260function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1261'<tt>normal</tt>' label or the
1262'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1263"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1264"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1265href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1266continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1267
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1268<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1269
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1270<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1271
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1272<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1273 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1274 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1275 convention</a> the call should use. If none is specified, the call defaults
1276 to using C calling conventions.
1277 </li>
1278 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1279 function value being invoked. In most cases, this is a direct function
1280 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1281 an arbitrary pointer to function value.
1282 </li>
1283
1284 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1285 function to be invoked. </li>
1286
1287 <li>'<tt>function args</tt>': argument list whose types match the function
1288 signature argument types. If the function signature indicates the function
1289 accepts a variable number of arguments, the extra arguments can be
1290 specified. </li>
1291
1292 <li>'<tt>normal label</tt>': the label reached when the called function
1293 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1294
1295 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1296 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1297
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1298</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1299
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1300<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1301
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1302<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1303href="#i_call">call</a></tt>' instruction in most regards. The primary
1304difference is that it establishes an association with a label, which is used by
1305the runtime library to unwind the stack.</p>
1306
1307<p>This instruction is used in languages with destructors to ensure that proper
1308cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1309exception. Additionally, this is important for implementation of
1310'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1311
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1312<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1313<pre>
1314 %retval = invoke int %Test(int 15) to label %Continue
1315 except label %TestCleanup <i>; {int}:retval set</i>
1316 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
1317 except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1318</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1319</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1320
1321
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1322<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1323
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1324<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1325Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1326
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1327<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1328
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1329<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1330<pre>
1331 unwind
1332</pre>
1333
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1334<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1335
1336<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1337at the first callee in the dynamic call stack which used an <a
1338href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1339primarily used to implement exception handling.</p>
1340
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1341<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1342
1343<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1344immediately halt. The dynamic call stack is then searched for the first <a
1345href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1346execution continues at the "exceptional" destination block specified by the
1347<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1348dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1349</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1350
1351<!-- _______________________________________________________________________ -->
1352
1353<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1354Instruction</a> </div>
1355
1356<div class="doc_text">
1357
1358<h5>Syntax:</h5>
1359<pre>
1360 unreachable
1361</pre>
1362
1363<h5>Overview:</h5>
1364
1365<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1366instruction is used to inform the optimizer that a particular portion of the
1367code is not reachable. This can be used to indicate that the code after a
1368no-return function cannot be reached, and other facts.</p>
1369
1370<h5>Semantics:</h5>
1371
1372<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1373</div>
1374
1375
1376
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1377<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1378<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1379<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1380<p>Binary operators are used to do most of the computation in a
1381program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1382produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1383multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1384The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1385necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1386<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1387</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1388<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1389<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1390Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1391<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1392<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1393<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]1394</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1395<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1396<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1397<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1398<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1399 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1400 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1401Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1402<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1403<p>The value produced is the integer or floating point sum of the two
1404operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1405<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1406<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]1407</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1408</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1409<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1410<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1411Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1412<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1413<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1414<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]1415</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1416<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1417<p>The '<tt>sub</tt>' instruction returns the difference of its two
1418operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1419<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1420instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1421<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1422<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1423 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1424values.
1425This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1426Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1427<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1428<p>The value produced is the integer or floating point difference of
1429the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1430<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1431<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]1432 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1433</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1434</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1435<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1436<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1437Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1438<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1439<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1440<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]1441</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1442<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1443<p>The '<tt>mul</tt>' instruction returns the product of its two
1444operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1445<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1446<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1447 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1448values.
1449This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1450Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1451<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1452<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1453two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1454<p>There is no signed vs unsigned multiplication. The appropriate
1455action is taken based on the type of the operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1456<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1457<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]1458</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1459</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1460<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1461<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1462Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1463<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1464<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1465<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1466</pre>
1467<h5>Overview:</h5>
1468<p>The '<tt>div</tt>' instruction returns the quotient of its two
1469operands.</p>
1470<h5>Arguments:</h5>
1471<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1472 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1473values.
1474This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1475Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1476<h5>Semantics:</h5>
1477<p>The value produced is the integer or floating point quotient of the
1478two operands.</p>
1479<h5>Example:</h5>
1480<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1481</pre>
1482</div>
1483<!-- _______________________________________________________________________ -->
1484<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1485Instruction</a> </div>
1486<div class="doc_text">
1487<h5>Syntax:</h5>
1488<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1489</pre>
1490<h5>Overview:</h5>
1491<p>The '<tt>rem</tt>' instruction returns the remainder from the
1492division of its two operands.</p>
1493<h5>Arguments:</h5>
1494<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1495 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1496values.
1497This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1498Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1499<h5>Semantics:</h5>
1500<p>This returns the <i>remainder</i> of a division (where the result
1501has the same sign as the divisor), not the <i>modulus</i> (where the
1502result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1503information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1504 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1505Math Forum</a>.</p>
1506<h5>Example:</h5>
1507<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1508</pre>
1509</div>
1510<!-- _______________________________________________________________________ -->
1511<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1512Instructions</a> </div>
1513<div class="doc_text">
1514<h5>Syntax:</h5>
1515<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]1516 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1517 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1518 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1519 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1520 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1521</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1522<h5>Overview:</h5>
1523<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1524value based on a comparison of their two operands.</p>
1525<h5>Arguments:</h5>
1526<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1527be of <a href="#t_firstclass">first class</a> type (it is not possible
1528to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1529or '<tt>void</tt>' values, etc...). Both arguments must have identical
1530types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1531<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1532<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1533value if both operands are equal.<br>
1534The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1535value if both operands are unequal.<br>
1536The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1537value if the first operand is less than the second operand.<br>
1538The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1539value if the first operand is greater than the second operand.<br>
1540The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1541value if the first operand is less than or equal to the second operand.<br>
1542The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1543value if the first operand is greater than or equal to the second
1544operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1545<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1546<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1547 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1548 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1549 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1550 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1551 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1552</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1553</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1554<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1555<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1556Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1557<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1558<p>Bitwise binary operators are used to do various forms of
1559bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1560instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1561instructions. They require two operands, execute an operation on them,
1562and produce a single value. The resulting value of the bitwise binary
1563operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1564</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1565<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1566<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1567Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1568<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1569<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1570<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]1571</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1572<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1573<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1574its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1575<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1576<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1577 href="#t_integral">integral</a> values. Both arguments must have
1578identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1579<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1580<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1581<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1582<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1583<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1584 <tbody>
1585 <tr>
1586 <td>In0</td>
1587 <td>In1</td>
1588 <td>Out</td>
1589 </tr>
1590 <tr>
1591 <td>0</td>
1592 <td>0</td>
1593 <td>0</td>
1594 </tr>
1595 <tr>
1596 <td>0</td>
1597 <td>1</td>
1598 <td>0</td>
1599 </tr>
1600 <tr>
1601 <td>1</td>
1602 <td>0</td>
1603 <td>0</td>
1604 </tr>
1605 <tr>
1606 <td>1</td>
1607 <td>1</td>
1608 <td>1</td>
1609 </tr>
1610 </tbody>
1611</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1612</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1613<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1614<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]1615 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1616 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1617</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1618</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1619<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1620<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1621<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1622<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1623<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]1624</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1625<h5>Overview:</h5>
1626<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1627or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1628<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1629<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1630 href="#t_integral">integral</a> values. Both arguments must have
1631identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1632<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1633<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1634<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1635<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1636<table border="1" cellspacing="0" cellpadding="4">
1637 <tbody>
1638 <tr>
1639 <td>In0</td>
1640 <td>In1</td>
1641 <td>Out</td>
1642 </tr>
1643 <tr>
1644 <td>0</td>
1645 <td>0</td>
1646 <td>0</td>
1647 </tr>
1648 <tr>
1649 <td>0</td>
1650 <td>1</td>
1651 <td>1</td>
1652 </tr>
1653 <tr>
1654 <td>1</td>
1655 <td>0</td>
1656 <td>1</td>
1657 </tr>
1658 <tr>
1659 <td>1</td>
1660 <td>1</td>
1661 <td>1</td>
1662 </tr>
1663 </tbody>
1664</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1665</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1666<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1667<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]1668 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1669 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1670</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1671</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1672<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1673<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1674Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1675<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1676<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1677<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]1678</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1679<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1680<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1681or of its two operands. The <tt>xor</tt> is used to implement the
1682"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1683<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1684<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1685 href="#t_integral">integral</a> values. Both arguments must have
1686identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1687<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1688<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1689<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1690<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1691<table border="1" cellspacing="0" cellpadding="4">
1692 <tbody>
1693 <tr>
1694 <td>In0</td>
1695 <td>In1</td>
1696 <td>Out</td>
1697 </tr>
1698 <tr>
1699 <td>0</td>
1700 <td>0</td>
1701 <td>0</td>
1702 </tr>
1703 <tr>
1704 <td>0</td>
1705 <td>1</td>
1706 <td>1</td>
1707 </tr>
1708 <tr>
1709 <td>1</td>
1710 <td>0</td>
1711 <td>1</td>
1712 </tr>
1713 <tr>
1714 <td>1</td>
1715 <td>1</td>
1716 <td>0</td>
1717 </tr>
1718 </tbody>
1719</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1720</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1721<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1722<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1723<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]1724 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1725 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1726 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1727</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1728</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1729<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1730<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1731Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1732<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1733<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1734<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]1735</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1736<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1737<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1738the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1739<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1740<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1741 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1742type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1743<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1744<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]1745<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1746<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]1747 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1748 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1749</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1750</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1751<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1752<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1753Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1754<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1755<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1756<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]1757</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1758<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1759<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1760the right a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1761<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1762<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1763 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1764type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1765<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1766<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1767most significant bit is duplicated in the newly free'd bit positions.
1768If the first argument is unsigned, zero bits shall fill the empty
1769positions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1770<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1771<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]1772 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1773 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1774 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1775 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1776</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1777</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1778
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1779<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1780<div class="doc_subsection">
1781 <a name="memoryops">Memory Access Operations</a>
1782</div>
1783
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1784<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1785
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1786<p>A key design point of an SSA-based representation is how it
1787represents memory. In LLVM, no memory locations are in SSA form, which
1788makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1789allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1790
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1791</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1792
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1793<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1794<div class="doc_subsubsection">
1795 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
1796</div>
1797
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1798<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1799
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1800<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1801
1802<pre>
1803 &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]1804</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1805
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1806<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1807
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1808<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1809heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1810
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1811<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1812
1813<p>The '<tt>malloc</tt>' instruction allocates
1814<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]1815bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1816appropriate type to the program. If "NumElements" is specified, it is the
1817number of elements allocated. If an alignment is specified, the value result
1818of the allocation is guaranteed to be aligned to at least that boundary. If
1819not specified, or if zero, the target can choose to align the allocation on any
1820convenient boundary.</p>
1821
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1822<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1823
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1824<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1825
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1826<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1827a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1828
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1829<h5>Example:</h5>
1830
1831<pre>
1832 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
1833
1834 %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]1835 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1836 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1837 %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
1838 %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1839</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1840</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1841
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1842<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1843<div class="doc_subsubsection">
1844 <a name="i_free">'<tt>free</tt>' Instruction</a>
1845</div>
1846
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1847<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1848
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1849<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1850
1851<pre>
1852 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1853</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1854
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1855<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1856
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1857<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1858memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1859
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1860<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1861
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1862<p>'<tt>value</tt>' shall be a pointer value that points to a value
1863that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1864instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1865
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1866<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1867
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1868<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1869after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1870
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1871<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1872
1873<pre>
1874 %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]1875 free [4 x ubyte]* %array
1876</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1877</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1878
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1879<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1880<div class="doc_subsubsection">
1881 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
1882</div>
1883
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1884<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1885
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1886<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1887
1888<pre>
1889 &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]1890</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1891
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1892<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1893
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1894<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1895stack frame of the procedure that is live until the current function
1896returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1897
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1898<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1899
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1900<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1901bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1902appropriate type to the program. If "NumElements" is specified, it is the
1903number of elements allocated. If an alignment is specified, the value result
1904of the allocation is guaranteed to be aligned to at least that boundary. If
1905not specified, or if zero, the target can choose to align the allocation on any
1906convenient boundary.</p>
1907
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1908<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1909
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1910<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1911
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1912<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1913memory is automatically released when the function returns. The '<tt>alloca</tt>'
1914instruction is commonly used to represent automatic variables that must
1915have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]1916 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]1917instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1918
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1919<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1920
1921<pre>
1922 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1923 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1924 %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
1925 %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1926</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1927</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame^]1928
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1929<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1930<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1931Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1932<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1933<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1934<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]1935<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1936<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1937<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1938<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1939address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]1940 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1941marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1942the number or order of execution of this <tt>load</tt> with other
1943volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1944instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1945<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1946<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1947<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1948<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1949 <a
1950 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1951 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1952</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1953</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1954<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1955<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1956Instruction</a> </div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1957<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1958<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]1959 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]1960</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1961<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1962<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1963<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1964<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1965to 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]1966operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1967operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1968optimizer is not allowed to modify the number or order of execution of
1969this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1970 href="#i_store">store</a></tt> instructions.</p>
1971<h5>Semantics:</h5>
1972<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1973at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1974<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1975<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1976 <a
1977 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1978 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1979</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1980<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1981<div class="doc_subsubsection">
1982 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
1983</div>
1984
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1985<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1986<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1987<pre>
1988 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
1989</pre>
1990
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1991<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1992
1993<p>
1994The '<tt>getelementptr</tt>' instruction is used to get the address of a
1995subelement of an aggregate data structure.</p>
1996
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1997<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]1998
1999<p>This instruction takes a list of integer constants that indicate what
2000elements of the aggregate object to index to. The actual types of the arguments
2001provided depend on the type of the first pointer argument. The
2002'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2003levels of a structure or to a specific index in an array. When indexing into a
2004structure, only <tt>uint</tt>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2005integer constants are allowed. When indexing into an array or pointer,
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2006<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
2007
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2008<p>For example, let's consider a C code fragment and how it gets
2009compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2010
2011<pre>
2012 struct RT {
2013 char A;
2014 int B[10][20];
2015 char C;
2016 };
2017 struct ST {
2018 int X;
2019 double Y;
2020 struct RT Z;
2021 };
2022
2023 int *foo(struct ST *s) {
2024 return &amp;s[1].Z.B[5][13];
2025 }
2026</pre>
2027
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2028<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2029
2030<pre>
2031 %RT = type { sbyte, [10 x [20 x int]], sbyte }
2032 %ST = type { int, double, %RT }
2033
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2034 implementation
2035
2036 int* %foo(%ST* %s) {
2037 entry:
2038 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2039 ret int* %reg
2040 }
2041</pre>
2042
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2043<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2044
2045<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2046on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2047and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
2048<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]2049types require <tt>uint</tt> <b>constants</b>.</p>
2050
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2051<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]2052type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
2053}</tt>' type, a structure. The second index indexes into the third element of
2054the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
2055sbyte }</tt>' type, another structure. The third index indexes into the second
2056element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
2057array. The two dimensions of the array are subscripted into, yielding an
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2058'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2059to this element, thus computing a value of '<tt>int*</tt>' type.</p>
2060
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2061<p>Note that it is perfectly legal to index partially through a
2062structure, returning a pointer to an inner element. Because of this,
2063the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2064
2065<pre>
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]2066 int* %foo(%ST* %s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2067 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
2068 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
2069 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
2070 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
2071 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
2072 ret int* %t5
2073 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2074</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2075
2076<p>Note that it is undefined to access an array out of bounds: array and
2077pointer indexes must always be within the defined bounds of the array type.
2078The one exception for this rules is zero length arrays. These arrays are
2079defined to be accessible as variable length arrays, which requires access
2080beyond the zero'th element.</p>
2081
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2082<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2083
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2084<pre>
2085 <i>; yields [12 x ubyte]*:aptr</i>
2086 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
2087</pre>
2088
2089</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2090<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2091<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2092<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]2093<p>The instructions in this category are the "miscellaneous"
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2094instructions, which defy better classification.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2095</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2096<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2097<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2098Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2099<div class="doc_text">
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2100<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2101<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]2102<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2103<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2104the SSA graph representing the function.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2105<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2106<p>The type of the incoming values are specified with the first type
2107field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2108as arguments, with one pair for each predecessor basic block of the
2109current block. Only values of <a href="#t_firstclass">first class</a>
2110type may be used as the value arguments to the PHI node. Only labels
2111may be used as the label arguments.</p>
2112<p>There must be no non-phi instructions between the start of a basic
2113block and the PHI instructions: i.e. PHI instructions must be first in
2114a basic block.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2115<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2116<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2117value specified by the parameter, depending on which basic block we
2118came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2119<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2120<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]2121</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2122
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2123<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2124<div class="doc_subsubsection">
2125 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2126</div>
2127
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2128<div class="doc_text">
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2129
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2130<h5>Syntax:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2131
2132<pre>
2133 &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]2134</pre>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2135
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2136<h5>Overview:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2137
2138<p>
2139The '<tt>cast</tt>' instruction is used as the primitive means to convert
2140integers to floating point, change data type sizes, and break type safety (by
2141casting pointers).
2142</p>
2143
2144
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2145<h5>Arguments:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2146
2147<p>
2148The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2149class value, and a type to cast it to, which must also be a <a
2150href="#t_firstclass">first class</a> type.
2151</p>
2152
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2153<h5>Semantics:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2154
2155<p>
2156This instruction follows the C rules for explicit casts when determining how the
2157data being cast must change to fit in its new container.
2158</p>
2159
2160<p>
2161When casting to bool, any value that would be considered true in the context of
2162a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2163all else are '<tt>false</tt>'.
2164</p>
2165
2166<p>
2167When extending an integral value from a type of one signness to another (for
2168example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2169<b>source</b> value is signed, and zero-extended if the source value is
2170unsigned. <tt>bool</tt> values are always zero extended into either zero or
2171one.
2172</p>
2173
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2174<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2175
2176<pre>
2177 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]2178 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2179</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2180</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2181
2182<!-- _______________________________________________________________________ -->
2183<div class="doc_subsubsection">
2184 <a name="i_select">'<tt>select</tt>' Instruction</a>
2185</div>
2186
2187<div class="doc_text">
2188
2189<h5>Syntax:</h5>
2190
2191<pre>
2192 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2193</pre>
2194
2195<h5>Overview:</h5>
2196
2197<p>
2198The '<tt>select</tt>' instruction is used to choose one value based on a
2199condition, without branching.
2200</p>
2201
2202
2203<h5>Arguments:</h5>
2204
2205<p>
2206The '<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.
2207</p>
2208
2209<h5>Semantics:</h5>
2210
2211<p>
2212If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2213value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2214</p>
2215
2216<h5>Example:</h5>
2217
2218<pre>
2219 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2220</pre>
2221</div>
2222
2223
2224
2225
2226
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2227<!-- _______________________________________________________________________ -->
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2228<div class="doc_subsubsection">
2229 <a name="i_call">'<tt>call</tt>' Instruction</a>
2230</div>
2231
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2232<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2233
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2234<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2235<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2236 &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]2237</pre>
2238
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2239<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2240
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2241<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2242
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2243<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2244
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2245<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2246
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2247<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2248 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2249 <p>The optional "tail" marker indicates whether the callee function accesses
2250 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2251 function call is eligible for tail call optimization. Note that calls may
2252 be marked "tail" even if they do not occur before a <a
2253 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2254 </li>
2255 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2256 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2257 convention</a> the call should use. If none is specified, the call defaults
2258 to using C calling conventions.
2259 </li>
2260 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2261 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2262 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2263 signature. This type can be omitted if the function is not varargs and
2264 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2265 </li>
2266 <li>
2267 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2268 be invoked. In most cases, this is a direct function invocation, but
2269 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2270 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2271 </li>
2272 <li>
2273 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]2274 function signature argument types. All arguments must be of
2275 <a href="#t_firstclass">first class</a> type. If the function signature
2276 indicates the function accepts a variable number of arguments, the extra
2277 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2278 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2279</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2280
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2281<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2282
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2283<p>The '<tt>call</tt>' instruction is used to cause control flow to
2284transfer to a specified function, with its incoming arguments bound to
2285the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2286instruction in the called function, control flow continues with the
2287instruction after the function call, and the return value of the
2288function is bound to the result argument. This is a simpler case of
2289the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2290
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2291<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2292
2293<pre>
2294 %retval = call int %test(int %argc)
2295 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2296 %X = tail call int %foo()
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2297 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2298</pre>
2299
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2300</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2301
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2302<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2303<div class="doc_subsubsection">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2304 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
2305</div>
2306
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2307<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2308
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2309<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2310
2311<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2312 &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]2313</pre>
2314
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2315<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2316
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2317<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2318the "variable argument" area of a function call. It is used to implement the
2319<tt>va_arg</tt> macro in C.</p>
2320
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2321<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2322
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2323<p>This instruction takes a <tt>va_list*</tt> value and the type of
2324the argument. It returns a value of the specified argument type and
2325increments the <tt>va_list</tt> to poin to the next argument. Again, the
2326actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2327
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2328<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2329
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2330<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
2331type from the specified <tt>va_list</tt> and causes the
2332<tt>va_list</tt> to point to the next argument. For more information,
2333see the variable argument handling <a href="#int_varargs">Intrinsic
2334Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2335
2336<p>It is legal for this instruction to be called in a function which does not
2337take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2338function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2339
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2340<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2341href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2342argument.</p>
2343
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2344<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2345
2346<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2347
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2348</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2349
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2350<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2351<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2352<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2353
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2354<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2355
2356<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2357well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2358restrictions. Overall, these instructions represent an extension mechanism for
2359the LLVM language that does not require changing all of the transformations in
2360LLVM to add to the language (or the bytecode reader/writer, the parser,
2361etc...).</p>
2362
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2363<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
2364prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2365this. Intrinsic functions must always be external functions: you cannot define
2366the body of intrinsic functions. Intrinsic functions may only be used in call
2367or invoke instructions: it is illegal to take the address of an intrinsic
2368function. Additionally, because intrinsic functions are part of the LLVM
2369language, it is required that they all be documented here if any are added.</p>
2370
2371
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2372<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]2373href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2374</p>
2375
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2376</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2377
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2378<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2379<div class="doc_subsection">
2380 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2381</div>
2382
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2383<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2384
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2385<p>Variable argument support is defined in LLVM with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2386 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
2387intrinsic functions. These functions are related to the similarly
2388named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2389
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2390<p>All of these functions operate on arguments that use a
2391target-specific value type "<tt>va_list</tt>". The LLVM assembly
2392language reference manual does not define what this type is, so all
2393transformations should be prepared to handle intrinsics with any type
2394used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2395
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2396<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2397instruction and the variable argument handling intrinsic functions are
2398used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2399
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2400<pre>
2401int %test(int %X, ...) {
2402 ; Initialize variable argument processing
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2403 %ap = alloca sbyte*
2404 call void %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2405
2406 ; Read a single integer argument
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2407 %tmp = va_arg sbyte** %ap, int
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2408
2409 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2410 %aq = alloca sbyte*
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2411 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]2412 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2413
2414 ; Stop processing of arguments.
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2415 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2416 ret int %tmp
2417}
2418</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2419</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2420
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2421<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2422<div class="doc_subsubsection">
2423 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2424</div>
2425
2426
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2427<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2428<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2429<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]2430<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2431<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
2432<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
2433href="#i_va_arg">va_arg</a></tt>.</p>
2434
2435<h5>Arguments:</h5>
2436
2437<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
2438
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2439<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2440
2441<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
2442macro available in C. In a target-dependent way, it initializes the
2443<tt>va_list</tt> element the argument points to, so that the next call to
2444<tt>va_arg</tt> will produce the first variable argument passed to the function.
2445Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2446last argument of the function, the compiler can figure that out.</p>
2447
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2448</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2449
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2450<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2451<div class="doc_subsubsection">
2452 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2453</div>
2454
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2455<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2456<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2457<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]2458<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2459<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2460which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2461or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2462<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2463<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2464<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2465<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]2466macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2467Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2468 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2469with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2470</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2471
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2472<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2473<div class="doc_subsubsection">
2474 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2475</div>
2476
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2477<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2478
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2479<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2480
2481<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2482 declare void %llvm.va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2483 &lt;va_list&gt;* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2484</pre>
2485
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2486<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2487
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2488<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
2489the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2490
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2491<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2492
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2493<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]2494The 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]2495
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2496
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2497<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2498
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2499<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
2500available in C. In a target-dependent way, it copies the source
2501<tt>va_list</tt> element into the destination list. This intrinsic is necessary
2502because 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]2503arbitrarily complex and require memory allocation, for example.</p>
2504
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2505</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2506
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2507<!-- ======================================================================= -->
2508<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2509 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2510</div>
2511
2512<div class="doc_text">
2513
2514<p>
2515LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2516Collection</a> requires the implementation and generation of these intrinsics.
2517These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2518stack</a>, as well as garbage collector implementations that require <a
2519href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2520Front-ends for type-safe garbage collected languages should generate these
2521intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2522href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2523</p>
2524</div>
2525
2526<!-- _______________________________________________________________________ -->
2527<div class="doc_subsubsection">
2528 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2529</div>
2530
2531<div class="doc_text">
2532
2533<h5>Syntax:</h5>
2534
2535<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2536 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2537</pre>
2538
2539<h5>Overview:</h5>
2540
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2541<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]2542the code generator, and allows some metadata to be associated with it.</p>
2543
2544<h5>Arguments:</h5>
2545
2546<p>The first argument specifies the address of a stack object that contains the
2547root pointer. The second pointer (which must be either a constant or a global
2548value address) contains the meta-data to be associated with the root.</p>
2549
2550<h5>Semantics:</h5>
2551
2552<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2553location. At compile-time, the code generator generates information to allow
2554the runtime to find the pointer at GC safe points.
2555</p>
2556
2557</div>
2558
2559
2560<!-- _______________________________________________________________________ -->
2561<div class="doc_subsubsection">
2562 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2563</div>
2564
2565<div class="doc_text">
2566
2567<h5>Syntax:</h5>
2568
2569<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2570 declare sbyte* %llvm.gcread(sbyte** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2571</pre>
2572
2573<h5>Overview:</h5>
2574
2575<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2576locations, allowing garbage collector implementations that require read
2577barriers.</p>
2578
2579<h5>Arguments:</h5>
2580
2581<p>The argument is the address to read from, which should be an address
2582allocated from the garbage collector.</p>
2583
2584<h5>Semantics:</h5>
2585
2586<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2587instruction, but may be replaced with substantially more complex code by the
2588garbage collector runtime, as needed.</p>
2589
2590</div>
2591
2592
2593<!-- _______________________________________________________________________ -->
2594<div class="doc_subsubsection">
2595 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2596</div>
2597
2598<div class="doc_text">
2599
2600<h5>Syntax:</h5>
2601
2602<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2603 declare void %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2604</pre>
2605
2606<h5>Overview:</h5>
2607
2608<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2609locations, allowing garbage collector implementations that require write
2610barriers (such as generational or reference counting collectors).</p>
2611
2612<h5>Arguments:</h5>
2613
2614<p>The first argument is the reference to store, and the second is the heap
2615location to store to.</p>
2616
2617<h5>Semantics:</h5>
2618
2619<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2620instruction, but may be replaced with substantially more complex code by the
2621garbage collector runtime, as needed.</p>
2622
2623</div>
2624
2625
2626
2627<!-- ======================================================================= -->
2628<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2629 <a name="int_codegen">Code Generator Intrinsics</a>
2630</div>
2631
2632<div class="doc_text">
2633<p>
2634These intrinsics are provided by LLVM to expose special features that may only
2635be implemented with code generator support.
2636</p>
2637
2638</div>
2639
2640<!-- _______________________________________________________________________ -->
2641<div class="doc_subsubsection">
2642 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2643</div>
2644
2645<div class="doc_text">
2646
2647<h5>Syntax:</h5>
2648<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2649 declare void* %llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2650</pre>
2651
2652<h5>Overview:</h5>
2653
2654<p>
2655The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2656indicating the return address of the current function or one of its callers.
2657</p>
2658
2659<h5>Arguments:</h5>
2660
2661<p>
2662The argument to this intrinsic indicates which function to return the address
2663for. Zero indicates the calling function, one indicates its caller, etc. The
2664argument is <b>required</b> to be a constant integer value.
2665</p>
2666
2667<h5>Semantics:</h5>
2668
2669<p>
2670The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2671the return address of the specified call frame, or zero if it cannot be
2672identified. The value returned by this intrinsic is likely to be incorrect or 0
2673for arguments other than zero, so it should only be used for debugging purposes.
2674</p>
2675
2676<p>
2677Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]2678aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2679source-language caller.
2680</p>
2681</div>
2682
2683
2684<!-- _______________________________________________________________________ -->
2685<div class="doc_subsubsection">
2686 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2687</div>
2688
2689<div class="doc_text">
2690
2691<h5>Syntax:</h5>
2692<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2693 declare void* %llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2694</pre>
2695
2696<h5>Overview:</h5>
2697
2698<p>
2699The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2700pointer value for the specified stack frame.
2701</p>
2702
2703<h5>Arguments:</h5>
2704
2705<p>
2706The argument to this intrinsic indicates which function to return the frame
2707pointer for. Zero indicates the calling function, one indicates its caller,
2708etc. The argument is <b>required</b> to be a constant integer value.
2709</p>
2710
2711<h5>Semantics:</h5>
2712
2713<p>
2714The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2715the frame address of the specified call frame, or zero if it cannot be
2716identified. The value returned by this intrinsic is likely to be incorrect or 0
2717for arguments other than zero, so it should only be used for debugging purposes.
2718</p>
2719
2720<p>
2721Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]2722aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2723source-language caller.
2724</p>
2725</div>
2726
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2727<!-- _______________________________________________________________________ -->
2728<div class="doc_subsubsection">
2729 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
2730</div>
2731
2732<div class="doc_text">
2733
2734<h5>Syntax:</h5>
2735<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2736 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
2737 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2738</pre>
2739
2740<h5>Overview:</h5>
2741
2742
2743<p>
2744The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2745a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
2746no
2747effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]2748characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2749</p>
2750
2751<h5>Arguments:</h5>
2752
2753<p>
2754<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
2755determining if the fetch should be for a read (0) or write (1), and
2756<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]2757locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2758<tt>locality</tt> arguments must be constant integers.
2759</p>
2760
2761<h5>Semantics:</h5>
2762
2763<p>
2764This intrinsic does not modify the behavior of the program. In particular,
2765prefetches cannot trap and do not produce a value. On targets that support this
2766intrinsic, the prefetch can provide hints to the processor cache for better
2767performance.
2768</p>
2769
2770</div>
2771
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2772<!-- _______________________________________________________________________ -->
2773<div class="doc_subsubsection">
2774 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
2775</div>
2776
2777<div class="doc_text">
2778
2779<h5>Syntax:</h5>
2780<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2781 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2782</pre>
2783
2784<h5>Overview:</h5>
2785
2786
2787<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2788The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
2789(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2790code to simulators and other tools. The method is target specific, but it is
2791expected that the marker will use exported symbols to transmit the PC of the marker.
2792The marker makes no guaranties that it will remain with any specific instruction
2793after optimizations. It is possible that the presense of a marker will inhibit
2794optimizations. The intended use is to be inserted after optmizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2795correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2796</p>
2797
2798<h5>Arguments:</h5>
2799
2800<p>
2801<tt>id</tt> is a numerical id identifying the marker.
2802</p>
2803
2804<h5>Semantics:</h5>
2805
2806<p>
2807This intrinsic does not modify the behavior of the program. Backends that do not
2808support this intrinisic may ignore it.
2809</p>
2810
2811</div>
2812
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2813
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2814<!-- ======================================================================= -->
2815<div class="doc_subsection">
2816 <a name="int_os">Operating System Intrinsics</a>
2817</div>
2818
2819<div class="doc_text">
2820<p>
2821These intrinsics are provided by LLVM to support the implementation of
2822operating system level code.
2823</p>
2824
2825</div>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2826
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2827<!-- _______________________________________________________________________ -->
2828<div class="doc_subsubsection">
2829 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2830</div>
2831
2832<div class="doc_text">
2833
2834<h5>Syntax:</h5>
2835<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2836 declare &lt;integer type&gt; %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2837</pre>
2838
2839<h5>Overview:</h5>
2840
2841<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2842The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2843I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2844</p>
2845
2846<h5>Arguments:</h5>
2847
2848<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2849The argument to this intrinsic indicates the hardware I/O address from which
2850to read the data. The address is in the hardware I/O address namespace (as
2851opposed to being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2852</p>
2853
2854<h5>Semantics:</h5>
2855
2856<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2857The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2858specified by <i>address</i> and returns the value. The address and return
2859value must be integers, but the size is dependent upon the platform upon which
2860the program is code generated. For example, on x86, the address must be an
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2861unsigned 16-bit value, and the return value must be 8, 16, or 32 bits.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2862</p>
2863
2864</div>
2865
2866<!-- _______________________________________________________________________ -->
2867<div class="doc_subsubsection">
2868 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2869</div>
2870
2871<div class="doc_text">
2872
2873<h5>Syntax:</h5>
2874<pre>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]2875 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
2876 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
2877 &lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2878</pre>
2879
2880<h5>Overview:</h5>
2881
2882<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2883The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2884I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2885</p>
2886
2887<h5>Arguments:</h5>
2888
2889<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2890The first argument is the value to write to the I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2891</p>
2892
2893<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2894The second argument indicates the hardware I/O address to which data should be
2895written. The address is in the hardware I/O address namespace (as opposed to
2896being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2897</p>
2898
2899<h5>Semantics:</h5>
2900
2901<p>
2902The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2903specified by <i>address</i>. The address and value must be integers, but the
2904size is dependent upon the platform upon which the program is code generated.
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2905For example, on x86, the address must be an unsigned 16-bit value, and the
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2906value written must be 8, 16, or 32 bits in length.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2907</p>
2908
2909</div>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2910
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2911<!-- _______________________________________________________________________ -->
2912<div class="doc_subsubsection">
2913 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
2914</div>
2915
2916<div class="doc_text">
2917
2918<h5>Syntax:</h5>
2919<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2920 declare &lt;result&gt; %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2921</pre>
2922
2923<h5>Overview:</h5>
2924
2925<p>
2926The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
2927address.
2928</p>
2929
2930<h5>Arguments:</h5>
2931
2932<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2933The argument to this intrinsic is a pointer indicating the memory address from
2934which to read the data. The data must be a
2935<a href="#t_firstclass">first class</a> type.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2936</p>
2937
2938<h5>Semantics:</h5>
2939
2940<p>
2941The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2942location specified by <i>pointer</i> and returns the value. The argument must
2943be a pointer, and the return value must be a
2944<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2945may not support I/O on all first class types. For example, 32-bit processors
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2946may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2947</p>
2948
2949<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2950This intrinsic enforces an in-order memory model for llvm.readio and
2951llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2952scheduled processors may execute loads and stores out of order, re-ordering at
2953run time accesses to memory mapped I/O registers. Using these intrinsics
2954ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2955</p>
2956
2957</div>
2958
2959<!-- _______________________________________________________________________ -->
2960<div class="doc_subsubsection">
2961 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
2962</div>
2963
2964<div class="doc_text">
2965
2966<h5>Syntax:</h5>
2967<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2968 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]2969</pre>
2970
2971<h5>Overview:</h5>
2972
2973<p>
2974The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
2975mapped I/O address.
2976</p>
2977
2978<h5>Arguments:</h5>
2979
2980<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2981The first argument is the value to write to the memory mapped I/O location.
2982The second argument is a pointer indicating the memory address to which the
2983data should be written.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2984</p>
2985
2986<h5>Semantics:</h5>
2987
2988<p>
2989The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2990I/O address specified by <i>pointer</i>. The value must be a
2991<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2992may not support I/O on all first class types. For example, 32-bit processors
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2993may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2994</p>
2995
2996<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2997This intrinsic enforces an in-order memory model for llvm.readio and
2998llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2999scheduled processors may execute loads and stores out of order, re-ordering at
3000run time accesses to memory mapped I/O registers. Using these intrinsics
3001ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3002</p>
3003
3004</div>
3005
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3006<!-- ======================================================================= -->
3007<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3008 <a name="int_libc">Standard C Library Intrinsics</a>
3009</div>
3010
3011<div class="doc_text">
3012<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3013LLVM provides intrinsics for a few important standard C library functions.
3014These intrinsics allow source-language front-ends to pass information about the
3015alignment of the pointer arguments to the code generator, providing opportunity
3016for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3017</p>
3018
3019</div>
3020
3021<!-- _______________________________________________________________________ -->
3022<div class="doc_subsubsection">
3023 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
3024</div>
3025
3026<div class="doc_text">
3027
3028<h5>Syntax:</h5>
3029<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3030 declare void %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3031 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3032</pre>
3033
3034<h5>Overview:</h5>
3035
3036<p>
3037The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3038location to the destination location.
3039</p>
3040
3041<p>
3042Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
3043does not return a value, and takes an extra alignment argument.
3044</p>
3045
3046<h5>Arguments:</h5>
3047
3048<p>
3049The first argument is a pointer to the destination, the second is a pointer to
3050the source. The third argument is an (arbitrarily sized) integer argument
3051specifying the number of bytes to copy, and the fourth argument is the alignment
3052of the source and destination locations.
3053</p>
3054
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]3055<p>
3056If the call to this intrinisic has an alignment value that is not 0 or 1, then
3057the caller guarantees that the size of the copy is a multiple of the alignment
3058and that both the source and destination pointers are aligned to that boundary.
3059</p>
3060
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3061<h5>Semantics:</h5>
3062
3063<p>
3064The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3065location to the destination location, which are not allowed to overlap. It
3066copies "len" bytes of memory over. If the argument is known to be aligned to
3067some boundary, this can be specified as the fourth argument, otherwise it should
3068be set to 0 or 1.
3069</p>
3070</div>
3071
3072
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3073<!-- _______________________________________________________________________ -->
3074<div class="doc_subsubsection">
3075 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3076</div>
3077
3078<div class="doc_text">
3079
3080<h5>Syntax:</h5>
3081<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3082 declare void %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3083 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3084</pre>
3085
3086<h5>Overview:</h5>
3087
3088<p>
3089The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
3090location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
3091intrinsic but allows the two memory locations to overlap.
3092</p>
3093
3094<p>
3095Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
3096does not return a value, and takes an extra alignment argument.
3097</p>
3098
3099<h5>Arguments:</h5>
3100
3101<p>
3102The first argument is a pointer to the destination, the second is a pointer to
3103the source. The third argument is an (arbitrarily sized) integer argument
3104specifying the number of bytes to copy, and the fourth argument is the alignment
3105of the source and destination locations.
3106</p>
3107
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]3108<p>
3109If the call to this intrinisic has an alignment value that is not 0 or 1, then
3110the caller guarantees that the size of the copy is a multiple of the alignment
3111and that both the source and destination pointers are aligned to that boundary.
3112</p>
3113
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3114<h5>Semantics:</h5>
3115
3116<p>
3117The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
3118location to the destination location, which may overlap. It
3119copies "len" bytes of memory over. If the argument is known to be aligned to
3120some boundary, this can be specified as the fourth argument, otherwise it should
3121be set to 0 or 1.
3122</p>
3123</div>
3124
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3125
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3126<!-- _______________________________________________________________________ -->
3127<div class="doc_subsubsection">
3128 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
3129</div>
3130
3131<div class="doc_text">
3132
3133<h5>Syntax:</h5>
3134<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3135 declare void %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3136 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3137</pre>
3138
3139<h5>Overview:</h5>
3140
3141<p>
3142The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
3143byte value.
3144</p>
3145
3146<p>
3147Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3148does not return a value, and takes an extra alignment argument.
3149</p>
3150
3151<h5>Arguments:</h5>
3152
3153<p>
3154The first argument is a pointer to the destination to fill, the second is the
3155byte value to fill it with, the third argument is an (arbitrarily sized) integer
3156argument specifying the number of bytes to fill, and the fourth argument is the
3157known alignment of destination location.
3158</p>
3159
3160<p>
3161If the call to this intrinisic has an alignment value that is not 0 or 1, then
3162the caller guarantees that the size of the copy is a multiple of the alignment
3163and that the destination pointer is aligned to that boundary.
3164</p>
3165
3166<h5>Semantics:</h5>
3167
3168<p>
3169The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
3170destination location. If the argument is known to be aligned to some boundary,
3171this can be specified as the fourth argument, otherwise it should be set to 0 or
31721.
3173</p>
3174</div>
3175
3176
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]3177<!-- _______________________________________________________________________ -->
3178<div class="doc_subsubsection">
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]3179 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
3180</div>
3181
3182<div class="doc_text">
3183
3184<h5>Syntax:</h5>
3185<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3186 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]3187</pre>
3188
3189<h5>Overview:</h5>
3190
3191<p>
3192The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
3193specified floating point values is a NAN.
3194</p>
3195
3196<h5>Arguments:</h5>
3197
3198<p>
3199The arguments are floating point numbers of the same type.
3200</p>
3201
3202<h5>Semantics:</h5>
3203
3204<p>
3205If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3206false.
3207</p>
3208</div>
3209
3210
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]3211<!-- _______________________________________________________________________ -->
3212<div class="doc_subsubsection">
3213 <a name="i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a>
3214</div>
3215
3216<div class="doc_text">
3217
3218<h5>Syntax:</h5>
3219<pre>
3220 declare &lt;float or double&gt; %llvm.sqrt(&lt;float or double&gt; Val)
3221</pre>
3222
3223<h5>Overview:</h5>
3224
3225<p>
3226The '<tt>llvm.sqrt</tt>' intrinsic returns the sqrt of the specified operand,
3227returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
3228<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
3229negative numbers (which allows for better optimization).
3230</p>
3231
3232<h5>Arguments:</h5>
3233
3234<p>
3235The argument and return value are floating point numbers of the same type.
3236</p>
3237
3238<h5>Semantics:</h5>
3239
3240<p>
3241This function returns the sqrt of the specified operand if it is a positive
3242floating point number.
3243</p>
3244</div>
3245
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3246<!-- ======================================================================= -->
3247<div class="doc_subsection">
3248 <a name="int_count">Bit Counting Intrinsics</a>
3249</div>
3250
3251<div class="doc_text">
3252<p>
3253LLVM provides intrinsics for a few important bit counting operations.
3254These allow efficient code generation for some algorithms.
3255</p>
3256
3257</div>
3258
3259<!-- _______________________________________________________________________ -->
3260<div class="doc_subsubsection">
3261 <a name="int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic</a>
3262</div>
3263
3264<div class="doc_text">
3265
3266<h5>Syntax:</h5>
3267<pre>
3268 declare int %llvm.ctpop(int &lt;src&gt;)
3269
3270</pre>
3271
3272<h5>Overview:</h5>
3273
3274<p>
3275The '<tt>llvm.ctpop</tt>' intrinsic counts the number of ones in a variable.
3276</p>
3277
3278<h5>Arguments:</h5>
3279
3280<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3281The only argument is the value to be counted. The argument may be of any
3282integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3283</p>
3284
3285<h5>Semantics:</h5>
3286
3287<p>
3288The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3289</p>
3290</div>
3291
3292<!-- _______________________________________________________________________ -->
3293<div class="doc_subsubsection">
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3294 <a name="int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic</a>
3295</div>
3296
3297<div class="doc_text">
3298
3299<h5>Syntax:</h5>
3300<pre>
3301 declare int %llvm.ctlz(int &lt;src&gt;)
3302
3303</pre>
3304
3305<h5>Overview:</h5>
3306
3307<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3308The '<tt>llvm.ctlz</tt>' intrinsic counts the number of leading zeros in a
3309variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3310</p>
3311
3312<h5>Arguments:</h5>
3313
3314<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3315The only argument is the value to be counted. The argument may be of any
3316integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3317</p>
3318
3319<h5>Semantics:</h5>
3320
3321<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3322The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
3323in a variable. If the src == 0 then the result is the size in bits of the type
3324of src. For example, <tt>llvm.cttz(int 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3325</p>
3326</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]3327
3328
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3329
3330<!-- _______________________________________________________________________ -->
3331<div class="doc_subsubsection">
3332 <a name="int_cttz">'<tt>llvm.cttz</tt>' Intrinsic</a>
3333</div>
3334
3335<div class="doc_text">
3336
3337<h5>Syntax:</h5>
3338<pre>
3339 declare int %llvm.cttz(int &lt;src&gt;)
3340
3341</pre>
3342
3343<h5>Overview:</h5>
3344
3345<p>
3346The '<tt>llvm.cttz</tt>' intrinsic counts the number of trailing zeros.
3347</p>
3348
3349<h5>Arguments:</h5>
3350
3351<p>
3352The only argument is the value to be counted. The argument may be of any
3353integer type. The return type must match the argument type.
3354</p>
3355
3356<h5>Semantics:</h5>
3357
3358<p>
3359The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
3360in a variable. If the src == 0 then the result is the size in bits of the type
3361of src. For example, <tt>llvm.cttz(2) = 1</tt>.
3362</p>
3363</div>
3364
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3365<!-- ======================================================================= -->
3366<div class="doc_subsection">
3367 <a name="int_debugger">Debugger Intrinsics</a>
3368</div>
3369
3370<div class="doc_text">
3371<p>
3372The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3373are described in the <a
3374href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3375Debugging</a> document.
3376</p>
3377</div>
3378
3379
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3380<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3381<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]3382<address>
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3387
3388 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
3389 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
3390 Last modified: $Date$
3391</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3392</body>
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