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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>
Robert Bocchino3a558662006-01-05 17:37:02 +0000[diff] [blame]103 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]104 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]105 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]106 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]107 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]108 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]109 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]110 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]111 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]112 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
113 <ol>
114 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
115 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
116 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
117 </ol>
118 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]119 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
120 <ol>
121 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
122 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
123 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
124 </ol>
125 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]126 <li><a href="#int_codegen">Code Generator Intrinsics</a>
127 <ol>
128 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
129 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]130 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]131 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]132 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]133 </ol>
134 </li>
135 <li><a href="#int_os">Operating System Intrinsics</a>
136 <ol>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]137 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
138 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]139 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
140 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]141 </ol>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]142 <li><a href="#int_libc">Standard C Library Intrinsics</a>
143 <ol>
144 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]145 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]146 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos96853722004-06-12 19:19:14 +0000[diff] [blame]147 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]148 <li><a href="#i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a></li>
149
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]150 </ol>
151 </li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]152 <li><a href="#int_count">Bit counting Intrinsics</a>
153 <ol>
154 <li><a href="#int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]155 <li><a href="#int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic </a></li>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]156 <li><a href="#int_cttz">'<tt>llvm.cttz</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]157 </ol>
158 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]159 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]160 </ol>
161 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]162</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]163
164<div class="doc_author">
165 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
166 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]167</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]168
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]169<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]170<div class="doc_section"> <a name="abstract">Abstract </a></div>
171<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]172
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]173<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]174<p>This document is a reference manual for the LLVM assembly language.
175LLVM is an SSA based representation that provides type safety,
176low-level operations, flexibility, and the capability of representing
177'all' high-level languages cleanly. It is the common code
178representation used throughout all phases of the LLVM compilation
179strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]180</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]181
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]182<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]183<div class="doc_section"> <a name="introduction">Introduction</a> </div>
184<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]185
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]186<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]187
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]188<p>The LLVM code representation is designed to be used in three
189different forms: as an in-memory compiler IR, as an on-disk bytecode
190representation (suitable for fast loading by a Just-In-Time compiler),
191and as a human readable assembly language representation. This allows
192LLVM to provide a powerful intermediate representation for efficient
193compiler transformations and analysis, while providing a natural means
194to debug and visualize the transformations. The three different forms
195of LLVM are all equivalent. This document describes the human readable
196representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]197
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]198<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]199while being expressive, typed, and extensible at the same time. It
200aims to be a "universal IR" of sorts, by being at a low enough level
201that high-level ideas may be cleanly mapped to it (similar to how
202microprocessors are "universal IR's", allowing many source languages to
203be mapped to them). By providing type information, LLVM can be used as
204the target of optimizations: for example, through pointer analysis, it
205can be proven that a C automatic variable is never accessed outside of
206the current function... allowing it to be promoted to a simple SSA
207value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]208
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]209</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]210
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]211<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]212<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]213
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]214<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]215
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]216<p>It is important to note that this document describes 'well formed'
217LLVM assembly language. There is a difference between what the parser
218accepts and what is considered 'well formed'. For example, the
219following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]220
221<pre>
222 %x = <a href="#i_add">add</a> int 1, %x
223</pre>
224
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]225<p>...because the definition of <tt>%x</tt> does not dominate all of
226its uses. The LLVM infrastructure provides a verification pass that may
227be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]228automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]229the optimizer before it outputs bytecode. The violations pointed out
230by the verifier pass indicate bugs in transformation passes or input to
231the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]232
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]233<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]234
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]235<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]236<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]237<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]238
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]239<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]240
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]241<p>LLVM uses three different forms of identifiers, for different
242purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]243
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]244<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]245 <li>Named values are represented as a string of characters with a '%' prefix.
246 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
247 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
248 Identifiers which require other characters in their names can be surrounded
249 with quotes. In this way, anything except a <tt>"</tt> character can be used
250 in a name.</li>
251
252 <li>Unnamed values are represented as an unsigned numeric value with a '%'
253 prefix. For example, %12, %2, %44.</li>
254
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]255 <li>Constants, which are described in a <a href="#constants">section about
256 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]257</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]258
259<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
260don't need to worry about name clashes with reserved words, and the set of
261reserved words may be expanded in the future without penalty. Additionally,
262unnamed identifiers allow a compiler to quickly come up with a temporary
263variable without having to avoid symbol table conflicts.</p>
264
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]265<p>Reserved words in LLVM are very similar to reserved words in other
266languages. There are keywords for different opcodes ('<tt><a
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]267href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
268href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
269href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
270and others. These reserved words cannot conflict with variable names, because
271none of them start with a '%' character.</p>
272
273<p>Here is an example of LLVM code to multiply the integer variable
274'<tt>%X</tt>' by 8:</p>
275
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]276<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]277
278<pre>
279 %result = <a href="#i_mul">mul</a> uint %X, 8
280</pre>
281
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]282<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]283
284<pre>
285 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
286</pre>
287
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]288<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]289
290<pre>
291 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
292 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
293 %result = <a href="#i_add">add</a> uint %1, %1
294</pre>
295
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]296<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
297important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]298
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]299<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]300
301 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
302 line.</li>
303
304 <li>Unnamed temporaries are created when the result of a computation is not
305 assigned to a named value.</li>
306
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]307 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]308
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]309</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]310
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]311<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]312demonstrating instructions, we will follow an instruction with a comment that
313defines the type and name of value produced. Comments are shown in italic
314text.</p>
315
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]316</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]317
318<!-- *********************************************************************** -->
319<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
320<!-- *********************************************************************** -->
321
322<!-- ======================================================================= -->
323<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
324</div>
325
326<div class="doc_text">
327
328<p>LLVM programs are composed of "Module"s, each of which is a
329translation unit of the input programs. Each module consists of
330functions, global variables, and symbol table entries. Modules may be
331combined together with the LLVM linker, which merges function (and
332global variable) definitions, resolves forward declarations, and merges
333symbol table entries. Here is an example of the "hello world" module:</p>
334
335<pre><i>; Declare the string constant as a global constant...</i>
336<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
337 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
338
339<i>; External declaration of the puts function</i>
340<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
341
342<i>; Definition of main function</i>
343int %main() { <i>; int()* </i>
344 <i>; Convert [13x sbyte]* to sbyte *...</i>
345 %cast210 = <a
346 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
347
348 <i>; Call puts function to write out the string to stdout...</i>
349 <a
350 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
351 <a
352 href="#i_ret">ret</a> int 0<br>}<br></pre>
353
354<p>This example is made up of a <a href="#globalvars">global variable</a>
355named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
356function, and a <a href="#functionstructure">function definition</a>
357for "<tt>main</tt>".</p>
358
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]359<p>In general, a module is made up of a list of global values,
360where both functions and global variables are global values. Global values are
361represented by a pointer to a memory location (in this case, a pointer to an
362array of char, and a pointer to a function), and have one of the following <a
363href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]364
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]365</div>
366
367<!-- ======================================================================= -->
368<div class="doc_subsection">
369 <a name="linkage">Linkage Types</a>
370</div>
371
372<div class="doc_text">
373
374<p>
375All Global Variables and Functions have one of the following types of linkage:
376</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]377
378<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]379
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]380 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]381
382 <dd>Global values with internal linkage are only directly accessible by
383 objects in the current module. In particular, linking code into a module with
384 an internal global value may cause the internal to be renamed as necessary to
385 avoid collisions. Because the symbol is internal to the module, all
386 references can be updated. This corresponds to the notion of the
387 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]388 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]389
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]390 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]391
392 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
393 the twist that linking together two modules defining the same
394 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
395 is typically used to implement inline functions. Unreferenced
396 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]397 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]398
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]399 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]400
401 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
402 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
403 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]404 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]405
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]406 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]407
408 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
409 pointer to array type. When two global variables with appending linkage are
410 linked together, the two global arrays are appended together. This is the
411 LLVM, typesafe, equivalent of having the system linker append together
412 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]413 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]414
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]415 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]416
417 <dd>If none of the above identifiers are used, the global is externally
418 visible, meaning that it participates in linkage and can be used to resolve
419 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]420 </dd>
421</dl>
422
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]423<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
424variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
425variable and was linked with this one, one of the two would be renamed,
426preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
427external (i.e., lacking any linkage declarations), they are accessible
428outside of the current module. It is illegal for a function <i>declaration</i>
429to have any linkage type other than "externally visible".</a></p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]430
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]431</div>
432
433<!-- ======================================================================= -->
434<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]435 <a name="callingconv">Calling Conventions</a>
436</div>
437
438<div class="doc_text">
439
440<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
441and <a href="#i_invoke">invokes</a> can all have an optional calling convention
442specified for the call. The calling convention of any pair of dynamic
443caller/callee must match, or the behavior of the program is undefined. The
444following calling conventions are supported by LLVM, and more may be added in
445the future:</p>
446
447<dl>
448 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
449
450 <dd>This calling convention (the default if no other calling convention is
451 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]452 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]453 prototype and implemented declaration of the function (as does normal C).
454 </dd>
455
456 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
457
458 <dd>This calling convention attempts to make calls as fast as possible
459 (e.g. by passing things in registers). This calling convention allows the
460 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]461 without having to conform to an externally specified ABI. Implementations of
462 this convention should allow arbitrary tail call optimization to be supported.
463 This calling convention does not support varargs and requires the prototype of
464 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]465 </dd>
466
467 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
468
469 <dd>This calling convention attempts to make code in the caller as efficient
470 as possible under the assumption that the call is not commonly executed. As
471 such, these calls often preserve all registers so that the call does not break
472 any live ranges in the caller side. This calling convention does not support
473 varargs and requires the prototype of all callees to exactly match the
474 prototype of the function definition.
475 </dd>
476
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]477 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]478
479 <dd>Any calling convention may be specified by number, allowing
480 target-specific calling conventions to be used. Target specific calling
481 conventions start at 64.
482 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]483</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]484
485<p>More calling conventions can be added/defined on an as-needed basis, to
486support pascal conventions or any other well-known target-independent
487convention.</p>
488
489</div>
490
491<!-- ======================================================================= -->
492<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]493 <a name="globalvars">Global Variables</a>
494</div>
495
496<div class="doc_text">
497
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]498<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]499instead of run-time. Global variables may optionally be initialized, may have
500an explicit section to be placed in, and may
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]501have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]502variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]503contents of the variable will <b>never</b> be modified (enabling better
504optimization, allowing the global data to be placed in the read-only section of
505an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]506cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]507
508<p>
509LLVM explicitly allows <em>declarations</em> of global variables to be marked
510constant, even if the final definition of the global is not. This capability
511can be used to enable slightly better optimization of the program, but requires
512the language definition to guarantee that optimizations based on the
513'constantness' are valid for the translation units that do not include the
514definition.
515</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]516
517<p>As SSA values, global variables define pointer values that are in
518scope (i.e. they dominate) all basic blocks in the program. Global
519variables always define a pointer to their "content" type because they
520describe a region of memory, and all memory objects in LLVM are
521accessed through pointers.</p>
522
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]523<p>LLVM allows an explicit section to be specified for globals. If the target
524supports it, it will emit globals to the section specified.</p>
525
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]526<p>An explicit alignment may be specified for a global. If not present, or if
527the alignment is set to zero, the alignment of the global is set by the target
528to whatever it feels convenient. If an explicit alignment is specified, the
529global is forced to have at least that much alignment. All alignments must be
530a power of 2.</p>
531
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]532</div>
533
534
535<!-- ======================================================================= -->
536<div class="doc_subsection">
537 <a name="functionstructure">Functions</a>
538</div>
539
540<div class="doc_text">
541
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]542<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
543type</a>, an optional <a href="#callingconv">calling convention</a>, a return
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]544type, a function name, a (possibly empty) argument list, an optional section,
545an optional alignment, an opening curly brace,
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]546a list of basic blocks, and a closing curly brace. LLVM function declarations
547are defined with the "<tt>declare</tt>" keyword, an optional <a
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]548href="#callingconv">calling convention</a>, a return type, a function name,
549a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]550
551<p>A function definition contains a list of basic blocks, forming the CFG for
552the function. Each basic block may optionally start with a label (giving the
553basic block a symbol table entry), contains a list of instructions, and ends
554with a <a href="#terminators">terminator</a> instruction (such as a branch or
555function return).</p>
556
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]557<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]558executed on entrance to the function, and it is not allowed to have predecessor
559basic blocks (i.e. there can not be any branches to the entry block of a
560function). Because the block can have no predecessors, it also cannot have any
561<a href="#i_phi">PHI nodes</a>.</p>
562
563<p>LLVM functions are identified by their name and type signature. Hence, two
564functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]565considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]566appropriately.</p>
567
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]568<p>LLVM allows an explicit section to be specified for functions. If the target
569supports it, it will emit functions to the section specified.</p>
570
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]571<p>An explicit alignment may be specified for a function. If not present, or if
572the alignment is set to zero, the alignment of the function is set by the target
573to whatever it feels convenient. If an explicit alignment is specified, the
574function is forced to have at least that much alignment. All alignments must be
575a power of 2.</p>
576
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]577</div>
578
579
580
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]581<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]582<div class="doc_section"> <a name="typesystem">Type System</a> </div>
583<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]584
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]585<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]586
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]587<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]588intermediate representation. Being typed enables a number of
589optimizations to be performed on the IR directly, without having to do
590extra analyses on the side before the transformation. A strong type
591system makes it easier to read the generated code and enables novel
592analyses and transformations that are not feasible to perform on normal
593three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]594
595</div>
596
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]597<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]598<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]599<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]600<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]601system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]602
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]603<table class="layout">
604 <tr class="layout">
605 <td class="left">
606 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]607 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]608 <tr><th>Type</th><th>Description</th></tr>
609 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]610 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
611 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
612 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
613 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
614 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]615 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]616 </tbody>
617 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]618 </td>
619 <td class="right">
620 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]621 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]622 <tr><th>Type</th><th>Description</th></tr>
623 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]624 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
625 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
626 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
627 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
628 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]629 </tbody>
630 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]631 </td>
632 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]633</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]634</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]635
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]636<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]637<div class="doc_subsubsection"> <a name="t_classifications">Type
638Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]639<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]640<p>These different primitive types fall into a few useful
641classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]642
643<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]644 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]645 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]646 <tr>
647 <td><a name="t_signed">signed</a></td>
648 <td><tt>sbyte, short, int, long, float, double</tt></td>
649 </tr>
650 <tr>
651 <td><a name="t_unsigned">unsigned</a></td>
652 <td><tt>ubyte, ushort, uint, ulong</tt></td>
653 </tr>
654 <tr>
655 <td><a name="t_integer">integer</a></td>
656 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
657 </tr>
658 <tr>
659 <td><a name="t_integral">integral</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]660 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
661 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]662 </tr>
663 <tr>
664 <td><a name="t_floating">floating point</a></td>
665 <td><tt>float, double</tt></td>
666 </tr>
667 <tr>
668 <td><a name="t_firstclass">first class</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]669 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
670 float, double, <a href="#t_pointer">pointer</a>,
671 <a href="#t_packed">packed</a></tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]672 </tr>
673 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]674</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]675
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]676<p>The <a href="#t_firstclass">first class</a> types are perhaps the
677most important. Values of these types are the only ones which can be
678produced by instructions, passed as arguments, or used as operands to
679instructions. This means that all structures and arrays must be
680manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]681</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]682
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]683<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]684<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]685
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]686<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]687
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]688<p>The real power in LLVM comes from the derived types in the system.
689This is what allows a programmer to represent arrays, functions,
690pointers, and other useful types. Note that these derived types may be
691recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]692
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]693</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]694
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]695<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]696<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]697
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]698<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]699
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]700<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]701
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]702<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]703sequentially in memory. The array type requires a size (number of
704elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]705
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]706<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]707
708<pre>
709 [&lt;# elements&gt; x &lt;elementtype&gt;]
710</pre>
711
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]712<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]713be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]714
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]715<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]716<table class="layout">
717 <tr class="layout">
718 <td class="left">
719 <tt>[40 x int ]</tt><br/>
720 <tt>[41 x int ]</tt><br/>
721 <tt>[40 x uint]</tt><br/>
722 </td>
723 <td class="left">
724 Array of 40 integer values.<br/>
725 Array of 41 integer values.<br/>
726 Array of 40 unsigned integer values.<br/>
727 </td>
728 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]729</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]730<p>Here are some examples of multidimensional arrays:</p>
731<table class="layout">
732 <tr class="layout">
733 <td class="left">
734 <tt>[3 x [4 x int]]</tt><br/>
735 <tt>[12 x [10 x float]]</tt><br/>
736 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
737 </td>
738 <td class="left">
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]739 3x4 array of integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]740 12x10 array of single precision floating point values.<br/>
741 2x3x4 array of unsigned integer values.<br/>
742 </td>
743 </tr>
744</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]745
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]746<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
747length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]748LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
749As a special case, however, zero length arrays are recognized to be variable
750length. This allows implementation of 'pascal style arrays' with the LLVM
751type "{ int, [0 x float]}", for example.</p>
752
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]753</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]754
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]755<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]756<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]757<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]758<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]759<p>The function type can be thought of as a function signature. It
760consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]761Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]762(which are structures of pointers to functions), for indirect function
763calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]764<p>
765The return type of a function type cannot be an aggregate type.
766</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]767<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]768<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]769<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]770specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]771which indicates that the function takes a variable number of arguments.
772Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]773 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]774<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]775<table class="layout">
776 <tr class="layout">
777 <td class="left">
778 <tt>int (int)</tt> <br/>
779 <tt>float (int, int *) *</tt><br/>
780 <tt>int (sbyte *, ...)</tt><br/>
781 </td>
782 <td class="left">
783 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
784 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]785 <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]786 returning <tt>float</tt>.<br/>
787 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
788 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
789 the signature for <tt>printf</tt> in LLVM.<br/>
790 </td>
791 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]792</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]793
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]794</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]795<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]796<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]797<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]798<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]799<p>The structure type is used to represent a collection of data members
800together in memory. The packing of the field types is defined to match
801the ABI of the underlying processor. The elements of a structure may
802be any type that has a size.</p>
803<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
804and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
805field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
806instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]807<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]808<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]809<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]810<table class="layout">
811 <tr class="layout">
812 <td class="left">
813 <tt>{ int, int, int }</tt><br/>
814 <tt>{ float, int (int) * }</tt><br/>
815 </td>
816 <td class="left">
817 a triple of three <tt>int</tt> values<br/>
818 A pair, where the first element is a <tt>float</tt> and the second element
819 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
820 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
821 </td>
822 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]823</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]824</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]825
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]826<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]827<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]828<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]829<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]830<p>As in many languages, the pointer type represents a pointer or
831reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]832<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]833<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]834<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]835<table class="layout">
836 <tr class="layout">
837 <td class="left">
838 <tt>[4x int]*</tt><br/>
839 <tt>int (int *) *</tt><br/>
840 </td>
841 <td class="left">
842 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
843 four <tt>int</tt> values<br/>
844 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattnera977c482005-02-19 02:22:14 +0000[diff] [blame]845 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]846 <tt>int</tt>.<br/>
847 </td>
848 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]849</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]850</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]851
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]852<!-- _______________________________________________________________________ -->
853<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]854<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]855
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]856<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]857
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]858<p>A packed type is a simple derived type that represents a vector
859of elements. Packed types are used when multiple primitive data
860are operated in parallel using a single instruction (SIMD).
861A packed type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]862elements) and an underlying primitive data type. Vectors must have a power
863of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]864considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]865
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]866<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]867
868<pre>
869 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
870</pre>
871
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]872<p>The number of elements is a constant integer value; elementtype may
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]873be any integral or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]874
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]875<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]876
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]877<table class="layout">
878 <tr class="layout">
879 <td class="left">
880 <tt>&lt;4 x int&gt;</tt><br/>
881 <tt>&lt;8 x float&gt;</tt><br/>
882 <tt>&lt;2 x uint&gt;</tt><br/>
883 </td>
884 <td class="left">
885 Packed vector of 4 integer values.<br/>
886 Packed vector of 8 floating-point values.<br/>
887 Packed vector of 2 unsigned integer values.<br/>
888 </td>
889 </tr>
890</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]891</div>
892
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]893<!-- _______________________________________________________________________ -->
894<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
895<div class="doc_text">
896
897<h5>Overview:</h5>
898
899<p>Opaque types are used to represent unknown types in the system. This
900corresponds (for example) to the C notion of a foward declared structure type.
901In LLVM, opaque types can eventually be resolved to any type (not just a
902structure type).</p>
903
904<h5>Syntax:</h5>
905
906<pre>
907 opaque
908</pre>
909
910<h5>Examples:</h5>
911
912<table class="layout">
913 <tr class="layout">
914 <td class="left">
915 <tt>opaque</tt>
916 </td>
917 <td class="left">
918 An opaque type.<br/>
919 </td>
920 </tr>
921</table>
922</div>
923
924
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]925<!-- *********************************************************************** -->
926<div class="doc_section"> <a name="constants">Constants</a> </div>
927<!-- *********************************************************************** -->
928
929<div class="doc_text">
930
931<p>LLVM has several different basic types of constants. This section describes
932them all and their syntax.</p>
933
934</div>
935
936<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]937<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]938
939<div class="doc_text">
940
941<dl>
942 <dt><b>Boolean constants</b></dt>
943
944 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
945 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
946 </dd>
947
948 <dt><b>Integer constants</b></dt>
949
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]950 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]951 href="#t_integer">integer</a> type. Negative numbers may be used with signed
952 integer types.
953 </dd>
954
955 <dt><b>Floating point constants</b></dt>
956
957 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
958 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]959 notation (see below). Floating point constants must have a <a
960 href="#t_floating">floating point</a> type. </dd>
961
962 <dt><b>Null pointer constants</b></dt>
963
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]964 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]965 and must be of <a href="#t_pointer">pointer type</a>.</dd>
966
967</dl>
968
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]969<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]970of floating point constants. For example, the form '<tt>double
9710x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
9724.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]973(and the only time that they are generated by the disassembler) is when a
974floating point constant must be emitted but it cannot be represented as a
975decimal floating point number. For example, NaN's, infinities, and other
976special values are represented in their IEEE hexadecimal format so that
977assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]978
979</div>
980
981<!-- ======================================================================= -->
982<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
983</div>
984
985<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]986<p>Aggregate constants arise from aggregation of simple constants
987and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]988
989<dl>
990 <dt><b>Structure constants</b></dt>
991
992 <dd>Structure constants are represented with notation similar to structure
993 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]994 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
995 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
996 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]997 types of elements must match those specified by the type.
998 </dd>
999
1000 <dt><b>Array constants</b></dt>
1001
1002 <dd>Array constants are represented with notation similar to array type
1003 definitions (a comma separated list of elements, surrounded by square brackets
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1004 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1005 constants must have <a href="#t_array">array type</a>, and the number and
1006 types of elements must match those specified by the type.
1007 </dd>
1008
1009 <dt><b>Packed constants</b></dt>
1010
1011 <dd>Packed constants are represented with notation similar to packed type
1012 definitions (a comma separated list of elements, surrounded by
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1013 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]1014 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
1015 href="#t_packed">packed type</a>, and the number and types of elements must
1016 match those specified by the type.
1017 </dd>
1018
1019 <dt><b>Zero initialization</b></dt>
1020
1021 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1022 value to zero of <em>any</em> type, including scalar and aggregate types.
1023 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]1024 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1025 initializers.
1026 </dd>
1027</dl>
1028
1029</div>
1030
1031<!-- ======================================================================= -->
1032<div class="doc_subsection">
1033 <a name="globalconstants">Global Variable and Function Addresses</a>
1034</div>
1035
1036<div class="doc_text">
1037
1038<p>The addresses of <a href="#globalvars">global variables</a> and <a
1039href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1040constants. These constants are explicitly referenced when the <a
1041href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1042href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1043file:</p>
1044
1045<pre>
1046 %X = global int 17
1047 %Y = global int 42
1048 %Z = global [2 x int*] [ int* %X, int* %Y ]
1049</pre>
1050
1051</div>
1052
1053<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1054<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1055<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1056 <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]1057 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1058 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1059
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1060 <p>Undefined values indicate to the compiler that the program is well defined
1061 no matter what value is used, giving the compiler more freedom to optimize.
1062 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1063</div>
1064
1065<!-- ======================================================================= -->
1066<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1067</div>
1068
1069<div class="doc_text">
1070
1071<p>Constant expressions are used to allow expressions involving other constants
1072to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1073href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1074that does not have side effects (e.g. load and call are not supported). The
1075following is the syntax for constant expressions:</p>
1076
1077<dl>
1078 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1079
1080 <dd>Cast a constant to another type.</dd>
1081
1082 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1083
1084 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1085 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1086 instruction, the index list may have zero or more indexes, which are required
1087 to make sense for the type of "CSTPTR".</dd>
1088
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1089 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1090
1091 <dd>Perform the <a href="#i_select">select operation</a> on
1092 constants.
1093
1094 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1095
1096 <dd>Perform the <a href="#i_extractelement">extractelement
1097 operation</a> on constants.
1098
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1099 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1100
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1101 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1102 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1103 binary</a> operations. The constraints on operands are the same as those for
1104 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1105 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1106</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1107</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1108
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1109<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1110<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1111<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1112
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1113<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1114
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1115<p>The LLVM instruction set consists of several different
1116classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1117instructions</a>, <a href="#binaryops">binary instructions</a>,
1118<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1119 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1120instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1121
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1122</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1123
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1124<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1125<div class="doc_subsection"> <a name="terminators">Terminator
1126Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1127
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1128<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1129
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1130<p>As mentioned <a href="#functionstructure">previously</a>, every
1131basic block in a program ends with a "Terminator" instruction, which
1132indicates which block should be executed after the current block is
1133finished. These terminator instructions typically yield a '<tt>void</tt>'
1134value: they produce control flow, not values (the one exception being
1135the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1136<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1137 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1138instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1139the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1140 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1141 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1142
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1143</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1144
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1145<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1146<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1147Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1148<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1149<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1150<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]1151 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1152</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1153<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1154<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1155value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1156<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1157returns a value and then causes control flow, and one that just causes
1158control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1159<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1160<p>The '<tt>ret</tt>' instruction may return any '<a
1161 href="#t_firstclass">first class</a>' type. Notice that a function is
1162not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1163instruction inside of the function that returns a value that does not
1164match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1165<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1166<p>When the '<tt>ret</tt>' instruction is executed, control flow
1167returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1168 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1169the instruction after the call. If the caller was an "<a
1170 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1171at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1172returns a value, that value shall set the call or invoke instruction's
1173return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1174<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1175<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1176 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1177</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1178</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1179<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1180<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1181<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1182<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1183<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]1184</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1185<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1186<p>The '<tt>br</tt>' instruction is used to cause control flow to
1187transfer to a different basic block in the current function. There are
1188two forms of this instruction, corresponding to a conditional branch
1189and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1190<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1191<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1192single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1193unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1194value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1195<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1196<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1197argument is evaluated. If the value is <tt>true</tt>, control flows
1198to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1199control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1200<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1201<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
1202 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]1203</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1204<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1205<div class="doc_subsubsection">
1206 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1207</div>
1208
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1209<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1210<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1211
1212<pre>
1213 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1214</pre>
1215
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1216<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1217
1218<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1219several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1220instruction, allowing a branch to occur to one of many possible
1221destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1222
1223
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1224<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1225
1226<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1227comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1228an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1229table is not allowed to contain duplicate constant entries.</p>
1230
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1231<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1232
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1233<p>The <tt>switch</tt> instruction specifies a table of values and
1234destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1235table is searched for the given value. If the value is found, control flow is
1236transfered to the corresponding destination; otherwise, control flow is
1237transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1238
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1239<h5>Implementation:</h5>
1240
1241<p>Depending on properties of the target machine and the particular
1242<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1243ways. For example, it could be generated as a series of chained conditional
1244branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1245
1246<h5>Example:</h5>
1247
1248<pre>
1249 <i>; Emulate a conditional br instruction</i>
1250 %Val = <a href="#i_cast">cast</a> bool %value to int
1251 switch int %Val, label %truedest [int 0, label %falsedest ]
1252
1253 <i>; Emulate an unconditional br instruction</i>
1254 switch uint 0, label %dest [ ]
1255
1256 <i>; Implement a jump table:</i>
1257 switch uint %val, label %otherwise [ uint 0, label %onzero
1258 uint 1, label %onone
1259 uint 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1260</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1261</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1262
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1263<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1264<div class="doc_subsubsection">
1265 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1266</div>
1267
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1268<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1269
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1270<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1271
1272<pre>
1273 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1274 to label &lt;normal label&gt; except label &lt;exception label&gt;
1275</pre>
1276
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1277<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1278
1279<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1280function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1281'<tt>normal</tt>' label or the
1282'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1283"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1284"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1285href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1286continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1287
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1288<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1289
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1290<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1291
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1292<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1293 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1294 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1295 convention</a> the call should use. If none is specified, the call defaults
1296 to using C calling conventions.
1297 </li>
1298 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1299 function value being invoked. In most cases, this is a direct function
1300 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1301 an arbitrary pointer to function value.
1302 </li>
1303
1304 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1305 function to be invoked. </li>
1306
1307 <li>'<tt>function args</tt>': argument list whose types match the function
1308 signature argument types. If the function signature indicates the function
1309 accepts a variable number of arguments, the extra arguments can be
1310 specified. </li>
1311
1312 <li>'<tt>normal label</tt>': the label reached when the called function
1313 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1314
1315 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1316 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1317
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1318</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1319
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1320<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1321
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1322<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1323href="#i_call">call</a></tt>' instruction in most regards. The primary
1324difference is that it establishes an association with a label, which is used by
1325the runtime library to unwind the stack.</p>
1326
1327<p>This instruction is used in languages with destructors to ensure that proper
1328cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1329exception. Additionally, this is important for implementation of
1330'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1331
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1332<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1333<pre>
1334 %retval = invoke int %Test(int 15) to label %Continue
1335 except label %TestCleanup <i>; {int}:retval set</i>
1336 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
1337 except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1338</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1339</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1340
1341
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1342<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1343
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1344<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1345Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1346
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1347<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1348
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1349<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1350<pre>
1351 unwind
1352</pre>
1353
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1354<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1355
1356<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1357at the first callee in the dynamic call stack which used an <a
1358href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1359primarily used to implement exception handling.</p>
1360
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1361<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1362
1363<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1364immediately halt. The dynamic call stack is then searched for the first <a
1365href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1366execution continues at the "exceptional" destination block specified by the
1367<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1368dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1369</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1370
1371<!-- _______________________________________________________________________ -->
1372
1373<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1374Instruction</a> </div>
1375
1376<div class="doc_text">
1377
1378<h5>Syntax:</h5>
1379<pre>
1380 unreachable
1381</pre>
1382
1383<h5>Overview:</h5>
1384
1385<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1386instruction is used to inform the optimizer that a particular portion of the
1387code is not reachable. This can be used to indicate that the code after a
1388no-return function cannot be reached, and other facts.</p>
1389
1390<h5>Semantics:</h5>
1391
1392<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1393</div>
1394
1395
1396
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1397<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1398<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1399<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1400<p>Binary operators are used to do most of the computation in a
1401program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1402produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1403multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1404The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1405necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1406<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1407</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1408<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1409<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1410Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1411<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1412<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1413<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]1414</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1415<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1416<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1417<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1418<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1419 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1420 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1421Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1422<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1423<p>The value produced is the integer or floating point sum of the two
1424operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1425<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1426<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]1427</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1428</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1429<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1430<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1431Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1432<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1433<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1434<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]1435</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1436<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1437<p>The '<tt>sub</tt>' instruction returns the difference of its two
1438operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1439<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1440instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1441<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1442<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1443 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1444values.
1445This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1446Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1447<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1448<p>The value produced is the integer or floating point difference of
1449the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1450<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1451<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]1452 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1453</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1454</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1455<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1456<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1457Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1458<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1459<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1460<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]1461</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1462<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1463<p>The '<tt>mul</tt>' instruction returns the product of its two
1464operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1465<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1466<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1467 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1468values.
1469This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1470Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1471<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1472<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1473two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1474<p>There is no signed vs unsigned multiplication. The appropriate
1475action is taken based on the type of the operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1476<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1477<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]1478</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1479</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1480<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1481<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1482Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1483<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1484<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1485<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1486</pre>
1487<h5>Overview:</h5>
1488<p>The '<tt>div</tt>' instruction returns the quotient of its two
1489operands.</p>
1490<h5>Arguments:</h5>
1491<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1492 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1493values.
1494This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1495Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1496<h5>Semantics:</h5>
1497<p>The value produced is the integer or floating point quotient of the
1498two operands.</p>
1499<h5>Example:</h5>
1500<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1501</pre>
1502</div>
1503<!-- _______________________________________________________________________ -->
1504<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1505Instruction</a> </div>
1506<div class="doc_text">
1507<h5>Syntax:</h5>
1508<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1509</pre>
1510<h5>Overview:</h5>
1511<p>The '<tt>rem</tt>' instruction returns the remainder from the
1512division of its two operands.</p>
1513<h5>Arguments:</h5>
1514<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1515 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1516values.
1517This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1518Both arguments must have identical types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1519<h5>Semantics:</h5>
1520<p>This returns the <i>remainder</i> of a division (where the result
1521has the same sign as the divisor), not the <i>modulus</i> (where the
1522result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1523information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1524 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1525Math Forum</a>.</p>
1526<h5>Example:</h5>
1527<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1528</pre>
1529</div>
1530<!-- _______________________________________________________________________ -->
1531<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1532Instructions</a> </div>
1533<div class="doc_text">
1534<h5>Syntax:</h5>
1535<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]1536 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1537 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1538 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1539 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1540 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1541</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1542<h5>Overview:</h5>
1543<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1544value based on a comparison of their two operands.</p>
1545<h5>Arguments:</h5>
1546<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1547be of <a href="#t_firstclass">first class</a> type (it is not possible
1548to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1549or '<tt>void</tt>' values, etc...). Both arguments must have identical
1550types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1551<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1552<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1553value if both operands are equal.<br>
1554The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1555value if both operands are unequal.<br>
1556The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1557value if the first operand is less than the second operand.<br>
1558The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1559value if the first operand is greater than the second operand.<br>
1560The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1561value if the first operand is less than or equal to the second operand.<br>
1562The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1563value if the first operand is greater than or equal to the second
1564operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1565<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1566<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1567 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1568 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1569 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1570 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1571 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1572</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1573</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1574<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1575<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1576Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1577<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1578<p>Bitwise binary operators are used to do various forms of
1579bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1580instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1581instructions. They require two operands, execute an operation on them,
1582and produce a single value. The resulting value of the bitwise binary
1583operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1584</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1585<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1586<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1587Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1588<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1589<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1590<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]1591</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1592<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1593<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1594its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1595<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1596<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1597 href="#t_integral">integral</a> values. Both arguments must have
1598identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1599<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1600<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1601<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1602<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1603<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1604 <tbody>
1605 <tr>
1606 <td>In0</td>
1607 <td>In1</td>
1608 <td>Out</td>
1609 </tr>
1610 <tr>
1611 <td>0</td>
1612 <td>0</td>
1613 <td>0</td>
1614 </tr>
1615 <tr>
1616 <td>0</td>
1617 <td>1</td>
1618 <td>0</td>
1619 </tr>
1620 <tr>
1621 <td>1</td>
1622 <td>0</td>
1623 <td>0</td>
1624 </tr>
1625 <tr>
1626 <td>1</td>
1627 <td>1</td>
1628 <td>1</td>
1629 </tr>
1630 </tbody>
1631</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1632</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1633<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1634<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]1635 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1636 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1637</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1638</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1639<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1640<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1641<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1642<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1643<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]1644</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1645<h5>Overview:</h5>
1646<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1647or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1648<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1649<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1650 href="#t_integral">integral</a> values. Both arguments must have
1651identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1652<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1653<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1654<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1655<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1656<table border="1" cellspacing="0" cellpadding="4">
1657 <tbody>
1658 <tr>
1659 <td>In0</td>
1660 <td>In1</td>
1661 <td>Out</td>
1662 </tr>
1663 <tr>
1664 <td>0</td>
1665 <td>0</td>
1666 <td>0</td>
1667 </tr>
1668 <tr>
1669 <td>0</td>
1670 <td>1</td>
1671 <td>1</td>
1672 </tr>
1673 <tr>
1674 <td>1</td>
1675 <td>0</td>
1676 <td>1</td>
1677 </tr>
1678 <tr>
1679 <td>1</td>
1680 <td>1</td>
1681 <td>1</td>
1682 </tr>
1683 </tbody>
1684</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1685</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1686<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1687<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]1688 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1689 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1690</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1691</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1692<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1693<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1694Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1695<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1696<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1697<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]1698</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1699<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1700<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1701or of its two operands. The <tt>xor</tt> is used to implement the
1702"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1703<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1704<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1705 href="#t_integral">integral</a> values. Both arguments must have
1706identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1707<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1708<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1709<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1710<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1711<table border="1" cellspacing="0" cellpadding="4">
1712 <tbody>
1713 <tr>
1714 <td>In0</td>
1715 <td>In1</td>
1716 <td>Out</td>
1717 </tr>
1718 <tr>
1719 <td>0</td>
1720 <td>0</td>
1721 <td>0</td>
1722 </tr>
1723 <tr>
1724 <td>0</td>
1725 <td>1</td>
1726 <td>1</td>
1727 </tr>
1728 <tr>
1729 <td>1</td>
1730 <td>0</td>
1731 <td>1</td>
1732 </tr>
1733 <tr>
1734 <td>1</td>
1735 <td>1</td>
1736 <td>0</td>
1737 </tr>
1738 </tbody>
1739</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1740</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1741<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1742<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1743<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]1744 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1745 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1746 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1747</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1748</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1749<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1750<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1751Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1752<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1753<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1754<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]1755</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1756<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1757<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1758the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1759<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1760<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1761 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1762type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1763<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1764<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]1765<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1766<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]1767 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1768 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1769</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1770</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1771<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1772<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1773Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1774<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1775<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1776<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]1777</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1778<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1779<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1780the right a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1781<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1782<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1783 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1784type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1785<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1786<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1787most significant bit is duplicated in the newly free'd bit positions.
1788If the first argument is unsigned, zero bits shall fill the empty
1789positions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1790<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1791<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]1792 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1793 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1794 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1795 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1796</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1797</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1798
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1799<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1800<div class="doc_subsection">
1801 <a name="memoryops">Memory Access Operations</a>
1802</div>
1803
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1804<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1805
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1806<p>A key design point of an SSA-based representation is how it
1807represents memory. In LLVM, no memory locations are in SSA form, which
1808makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1809allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1810
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1811</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1812
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1813<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1814<div class="doc_subsubsection">
1815 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
1816</div>
1817
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1818<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1819
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1820<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1821
1822<pre>
1823 &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]1824</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1825
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1826<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1827
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1828<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1829heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1830
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1831<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1832
1833<p>The '<tt>malloc</tt>' instruction allocates
1834<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]1835bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1836appropriate type to the program. If "NumElements" is specified, it is the
1837number of elements allocated. If an alignment is specified, the value result
1838of the allocation is guaranteed to be aligned to at least that boundary. If
1839not specified, or if zero, the target can choose to align the allocation on any
1840convenient boundary.</p>
1841
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1842<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1843
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1844<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1845
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1846<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1847a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1848
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1849<h5>Example:</h5>
1850
1851<pre>
1852 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
1853
1854 %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]1855 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1856 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1857 %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
1858 %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1859</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1860</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1861
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1862<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1863<div class="doc_subsubsection">
1864 <a name="i_free">'<tt>free</tt>' Instruction</a>
1865</div>
1866
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1867<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1868
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1869<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1870
1871<pre>
1872 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1873</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1874
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1875<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1876
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1877<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1878memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1879
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1880<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1881
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1882<p>'<tt>value</tt>' shall be a pointer value that points to a value
1883that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1884instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1885
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1886<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1887
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1888<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1889after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1890
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1891<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1892
1893<pre>
1894 %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]1895 free [4 x ubyte]* %array
1896</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1897</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1898
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1899<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1900<div class="doc_subsubsection">
1901 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
1902</div>
1903
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1904<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1905
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1906<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1907
1908<pre>
1909 &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]1910</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1911
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1912<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1913
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1914<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1915stack frame of the procedure that is live until the current function
1916returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1917
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1918<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1919
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1920<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1921bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1922appropriate type to the program. If "NumElements" is specified, it is the
1923number of elements allocated. If an alignment is specified, the value result
1924of the allocation is guaranteed to be aligned to at least that boundary. If
1925not specified, or if zero, the target can choose to align the allocation on any
1926convenient boundary.</p>
1927
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1928<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1929
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1930<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1931
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1932<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1933memory is automatically released when the function returns. The '<tt>alloca</tt>'
1934instruction is commonly used to represent automatic variables that must
1935have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]1936 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]1937instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1938
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1939<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1940
1941<pre>
1942 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1943 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1944 %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
1945 %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1946</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1947</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]1948
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1949<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1950<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1951Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1952<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1953<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1954<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]1955<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1956<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1957<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1958<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1959address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]1960 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1961marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1962the number or order of execution of this <tt>load</tt> with other
1963volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1964instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1965<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1966<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1967<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1968<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1969 <a
1970 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1971 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1972</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1973</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1974<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1975<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1976Instruction</a> </div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1977<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1978<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]1979 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]1980</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1981<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1982<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1983<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1984<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1985to 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]1986operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1987operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1988optimizer is not allowed to modify the number or order of execution of
1989this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1990 href="#i_store">store</a></tt> instructions.</p>
1991<h5>Semantics:</h5>
1992<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1993at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1994<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1995<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1996 <a
1997 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1998 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1999</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2000<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2001<div class="doc_subsubsection">
2002 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2003</div>
2004
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2005<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2006<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2007<pre>
2008 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2009</pre>
2010
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2011<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2012
2013<p>
2014The '<tt>getelementptr</tt>' instruction is used to get the address of a
2015subelement of an aggregate data structure.</p>
2016
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2017<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2018
2019<p>This instruction takes a list of integer constants that indicate what
2020elements of the aggregate object to index to. The actual types of the arguments
2021provided depend on the type of the first pointer argument. The
2022'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2023levels of a structure or to a specific index in an array. When indexing into a
2024structure, only <tt>uint</tt>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2025integer constants are allowed. When indexing into an array or pointer,
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2026<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
2027
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2028<p>For example, let's consider a C code fragment and how it gets
2029compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2030
2031<pre>
2032 struct RT {
2033 char A;
2034 int B[10][20];
2035 char C;
2036 };
2037 struct ST {
2038 int X;
2039 double Y;
2040 struct RT Z;
2041 };
2042
2043 int *foo(struct ST *s) {
2044 return &amp;s[1].Z.B[5][13];
2045 }
2046</pre>
2047
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2048<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2049
2050<pre>
2051 %RT = type { sbyte, [10 x [20 x int]], sbyte }
2052 %ST = type { int, double, %RT }
2053
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2054 implementation
2055
2056 int* %foo(%ST* %s) {
2057 entry:
2058 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2059 ret int* %reg
2060 }
2061</pre>
2062
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2063<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2064
2065<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2066on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2067and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
2068<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]2069types require <tt>uint</tt> <b>constants</b>.</p>
2070
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2071<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]2072type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
2073}</tt>' type, a structure. The second index indexes into the third element of
2074the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
2075sbyte }</tt>' type, another structure. The third index indexes into the second
2076element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
2077array. The two dimensions of the array are subscripted into, yielding an
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2078'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2079to this element, thus computing a value of '<tt>int*</tt>' type.</p>
2080
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2081<p>Note that it is perfectly legal to index partially through a
2082structure, returning a pointer to an inner element. Because of this,
2083the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2084
2085<pre>
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]2086 int* %foo(%ST* %s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2087 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
2088 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
2089 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
2090 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
2091 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
2092 ret int* %t5
2093 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2094</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2095
2096<p>Note that it is undefined to access an array out of bounds: array and
2097pointer indexes must always be within the defined bounds of the array type.
2098The one exception for this rules is zero length arrays. These arrays are
2099defined to be accessible as variable length arrays, which requires access
2100beyond the zero'th element.</p>
2101
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2102<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2103
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2104<pre>
2105 <i>; yields [12 x ubyte]*:aptr</i>
2106 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
2107</pre>
2108
2109</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2110<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2111<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2112<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]2113<p>The instructions in this category are the "miscellaneous"
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2114instructions, which defy better classification.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2115</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2116<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2117<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2118Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2119<div class="doc_text">
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2120<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2121<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]2122<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2123<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2124the SSA graph representing the function.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2125<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2126<p>The type of the incoming values are specified with the first type
2127field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2128as arguments, with one pair for each predecessor basic block of the
2129current block. Only values of <a href="#t_firstclass">first class</a>
2130type may be used as the value arguments to the PHI node. Only labels
2131may be used as the label arguments.</p>
2132<p>There must be no non-phi instructions between the start of a basic
2133block and the PHI instructions: i.e. PHI instructions must be first in
2134a basic block.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2135<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2136<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2137value specified by the parameter, depending on which basic block we
2138came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2139<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2140<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]2141</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2142
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2143<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2144<div class="doc_subsubsection">
2145 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2146</div>
2147
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2148<div class="doc_text">
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2149
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2150<h5>Syntax:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2151
2152<pre>
2153 &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]2154</pre>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2155
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2156<h5>Overview:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2157
2158<p>
2159The '<tt>cast</tt>' instruction is used as the primitive means to convert
2160integers to floating point, change data type sizes, and break type safety (by
2161casting pointers).
2162</p>
2163
2164
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2165<h5>Arguments:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2166
2167<p>
2168The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2169class value, and a type to cast it to, which must also be a <a
2170href="#t_firstclass">first class</a> type.
2171</p>
2172
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2173<h5>Semantics:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2174
2175<p>
2176This instruction follows the C rules for explicit casts when determining how the
2177data being cast must change to fit in its new container.
2178</p>
2179
2180<p>
2181When casting to bool, any value that would be considered true in the context of
2182a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2183all else are '<tt>false</tt>'.
2184</p>
2185
2186<p>
2187When extending an integral value from a type of one signness to another (for
2188example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2189<b>source</b> value is signed, and zero-extended if the source value is
2190unsigned. <tt>bool</tt> values are always zero extended into either zero or
2191one.
2192</p>
2193
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2194<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2195
2196<pre>
2197 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]2198 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2199</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2200</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2201
2202<!-- _______________________________________________________________________ -->
2203<div class="doc_subsubsection">
2204 <a name="i_select">'<tt>select</tt>' Instruction</a>
2205</div>
2206
2207<div class="doc_text">
2208
2209<h5>Syntax:</h5>
2210
2211<pre>
2212 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2213</pre>
2214
2215<h5>Overview:</h5>
2216
2217<p>
2218The '<tt>select</tt>' instruction is used to choose one value based on a
2219condition, without branching.
2220</p>
2221
2222
2223<h5>Arguments:</h5>
2224
2225<p>
2226The '<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.
2227</p>
2228
2229<h5>Semantics:</h5>
2230
2231<p>
2232If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2233value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2234</p>
2235
2236<h5>Example:</h5>
2237
2238<pre>
2239 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2240</pre>
2241</div>
2242
2243
Robert Bocchino3a558662006-01-05 17:37:02 +0000[diff] [blame]2244<!-- _______________________________________________________________________ -->
2245<div class="doc_subsubsection">
2246 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2247</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2248
Robert Bocchino3a558662006-01-05 17:37:02 +0000[diff] [blame]2249<div class="doc_text">
2250
2251<h5>Syntax:</h5>
2252
2253<pre>
2254 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, uint &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2255</pre>
2256
2257<h5>Overview:</h5>
2258
2259<p>
2260The '<tt>extractelement</tt>' instruction extracts a single scalar
2261element from a vector at a specified index.
2262</p>
2263
2264
2265<h5>Arguments:</h5>
2266
2267<p>
2268The first operand of an '<tt>extractelement</tt>' instruction is a
2269value of <a href="#t_packed">packed</a> type. The second operand is
2270an index indicating the position from which to extract the element.
2271The index may be a variable.</p>
2272
2273<h5>Semantics:</h5>
2274
2275<p>
2276The result is a scalar of the same type as the element type of
2277<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2278<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2279results are undefined.
2280</p>
2281
2282<h5>Example:</h5>
2283
2284<pre>
2285 %result = extractelement &lt;4 x int&gt; %vec, uint 0 <i>; yields int</i>
2286</pre>
2287</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2288
2289
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2290<!-- _______________________________________________________________________ -->
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2291<div class="doc_subsubsection">
2292 <a name="i_call">'<tt>call</tt>' Instruction</a>
2293</div>
2294
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2295<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2296
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2297<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2298<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2299 &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]2300</pre>
2301
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2302<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2303
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2304<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2305
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2306<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2307
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2308<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2309
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2310<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2311 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2312 <p>The optional "tail" marker indicates whether the callee function accesses
2313 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2314 function call is eligible for tail call optimization. Note that calls may
2315 be marked "tail" even if they do not occur before a <a
2316 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2317 </li>
2318 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2319 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2320 convention</a> the call should use. If none is specified, the call defaults
2321 to using C calling conventions.
2322 </li>
2323 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2324 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2325 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2326 signature. This type can be omitted if the function is not varargs and
2327 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2328 </li>
2329 <li>
2330 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2331 be invoked. In most cases, this is a direct function invocation, but
2332 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2333 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2334 </li>
2335 <li>
2336 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]2337 function signature argument types. All arguments must be of
2338 <a href="#t_firstclass">first class</a> type. If the function signature
2339 indicates the function accepts a variable number of arguments, the extra
2340 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2341 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2342</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2343
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2344<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2345
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2346<p>The '<tt>call</tt>' instruction is used to cause control flow to
2347transfer to a specified function, with its incoming arguments bound to
2348the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2349instruction in the called function, control flow continues with the
2350instruction after the function call, and the return value of the
2351function is bound to the result argument. This is a simpler case of
2352the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2353
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2354<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2355
2356<pre>
2357 %retval = call int %test(int %argc)
2358 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2359 %X = tail call int %foo()
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]2360 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]2361</pre>
2362
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2363</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2364
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2365<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2366<div class="doc_subsubsection">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2367 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
2368</div>
2369
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2370<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2371
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2372<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2373
2374<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2375 &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]2376</pre>
2377
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2378<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2379
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2380<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2381the "variable argument" area of a function call. It is used to implement the
2382<tt>va_arg</tt> macro in C.</p>
2383
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2384<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2385
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2386<p>This instruction takes a <tt>va_list*</tt> value and the type of
2387the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]2388increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2389actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2390
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2391<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2392
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2393<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
2394type from the specified <tt>va_list</tt> and causes the
2395<tt>va_list</tt> to point to the next argument. For more information,
2396see the variable argument handling <a href="#int_varargs">Intrinsic
2397Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2398
2399<p>It is legal for this instruction to be called in a function which does not
2400take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2401function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2402
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2403<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2404href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2405argument.</p>
2406
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]2407<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]2408
2409<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2410
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2411</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2412
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2413<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2414<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2415<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2416
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2417<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2418
2419<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2420well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2421restrictions. Overall, these instructions represent an extension mechanism for
2422the LLVM language that does not require changing all of the transformations in
2423LLVM to add to the language (or the bytecode reader/writer, the parser,
2424etc...).</p>
2425
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2426<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
2427prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2428this. Intrinsic functions must always be external functions: you cannot define
2429the body of intrinsic functions. Intrinsic functions may only be used in call
2430or invoke instructions: it is illegal to take the address of an intrinsic
2431function. Additionally, because intrinsic functions are part of the LLVM
2432language, it is required that they all be documented here if any are added.</p>
2433
2434
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2435<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]2436href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2437</p>
2438
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2439</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2440
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2441<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2442<div class="doc_subsection">
2443 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2444</div>
2445
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2446<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2447
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2448<p>Variable argument support is defined in LLVM with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2449 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
2450intrinsic functions. These functions are related to the similarly
2451named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2452
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2453<p>All of these functions operate on arguments that use a
2454target-specific value type "<tt>va_list</tt>". The LLVM assembly
2455language reference manual does not define what this type is, so all
2456transformations should be prepared to handle intrinsics with any type
2457used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2458
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2459<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2460instruction and the variable argument handling intrinsic functions are
2461used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2462
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2463<pre>
2464int %test(int %X, ...) {
2465 ; Initialize variable argument processing
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2466 %ap = alloca sbyte*
2467 call void %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2468
2469 ; Read a single integer argument
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2470 %tmp = va_arg sbyte** %ap, int
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2471
2472 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2473 %aq = alloca sbyte*
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2474 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]2475 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2476
2477 ; Stop processing of arguments.
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2478 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2479 ret int %tmp
2480}
2481</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2482</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2483
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2484<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2485<div class="doc_subsubsection">
2486 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2487</div>
2488
2489
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2490<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2491<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2492<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]2493<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2494<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
2495<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
2496href="#i_va_arg">va_arg</a></tt>.</p>
2497
2498<h5>Arguments:</h5>
2499
2500<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
2501
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2502<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2503
2504<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
2505macro available in C. In a target-dependent way, it initializes the
2506<tt>va_list</tt> element the argument points to, so that the next call to
2507<tt>va_arg</tt> will produce the first variable argument passed to the function.
2508Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2509last argument of the function, the compiler can figure that out.</p>
2510
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2511</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2512
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2513<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2514<div class="doc_subsubsection">
2515 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2516</div>
2517
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2518<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2519<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2520<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]2521<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2522<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2523which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2524or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2525<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2526<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2527<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2528<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]2529macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2530Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2531 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2532with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2533</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2534
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2535<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2536<div class="doc_subsubsection">
2537 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2538</div>
2539
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2540<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2541
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2542<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2543
2544<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2545 declare void %llvm.va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]2546 &lt;va_list&gt;* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2547</pre>
2548
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2549<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2550
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2551<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
2552the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2553
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2554<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2555
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2556<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]2557The 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]2558
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2559
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2560<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2561
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]2562<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
2563available in C. In a target-dependent way, it copies the source
2564<tt>va_list</tt> element into the destination list. This intrinsic is necessary
2565because 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]2566arbitrarily complex and require memory allocation, for example.</p>
2567
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2568</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]2569
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]2570<!-- ======================================================================= -->
2571<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2572 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2573</div>
2574
2575<div class="doc_text">
2576
2577<p>
2578LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2579Collection</a> requires the implementation and generation of these intrinsics.
2580These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2581stack</a>, as well as garbage collector implementations that require <a
2582href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2583Front-ends for type-safe garbage collected languages should generate these
2584intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2585href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2586</p>
2587</div>
2588
2589<!-- _______________________________________________________________________ -->
2590<div class="doc_subsubsection">
2591 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2592</div>
2593
2594<div class="doc_text">
2595
2596<h5>Syntax:</h5>
2597
2598<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2599 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2600</pre>
2601
2602<h5>Overview:</h5>
2603
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2604<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]2605the code generator, and allows some metadata to be associated with it.</p>
2606
2607<h5>Arguments:</h5>
2608
2609<p>The first argument specifies the address of a stack object that contains the
2610root pointer. The second pointer (which must be either a constant or a global
2611value address) contains the meta-data to be associated with the root.</p>
2612
2613<h5>Semantics:</h5>
2614
2615<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2616location. At compile-time, the code generator generates information to allow
2617the runtime to find the pointer at GC safe points.
2618</p>
2619
2620</div>
2621
2622
2623<!-- _______________________________________________________________________ -->
2624<div class="doc_subsubsection">
2625 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2626</div>
2627
2628<div class="doc_text">
2629
2630<h5>Syntax:</h5>
2631
2632<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2633 declare sbyte* %llvm.gcread(sbyte** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2634</pre>
2635
2636<h5>Overview:</h5>
2637
2638<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2639locations, allowing garbage collector implementations that require read
2640barriers.</p>
2641
2642<h5>Arguments:</h5>
2643
2644<p>The argument is the address to read from, which should be an address
2645allocated from the garbage collector.</p>
2646
2647<h5>Semantics:</h5>
2648
2649<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2650instruction, but may be replaced with substantially more complex code by the
2651garbage collector runtime, as needed.</p>
2652
2653</div>
2654
2655
2656<!-- _______________________________________________________________________ -->
2657<div class="doc_subsubsection">
2658 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2659</div>
2660
2661<div class="doc_text">
2662
2663<h5>Syntax:</h5>
2664
2665<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2666 declare void %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]2667</pre>
2668
2669<h5>Overview:</h5>
2670
2671<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2672locations, allowing garbage collector implementations that require write
2673barriers (such as generational or reference counting collectors).</p>
2674
2675<h5>Arguments:</h5>
2676
2677<p>The first argument is the reference to store, and the second is the heap
2678location to store to.</p>
2679
2680<h5>Semantics:</h5>
2681
2682<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2683instruction, but may be replaced with substantially more complex code by the
2684garbage collector runtime, as needed.</p>
2685
2686</div>
2687
2688
2689
2690<!-- ======================================================================= -->
2691<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2692 <a name="int_codegen">Code Generator Intrinsics</a>
2693</div>
2694
2695<div class="doc_text">
2696<p>
2697These intrinsics are provided by LLVM to expose special features that may only
2698be implemented with code generator support.
2699</p>
2700
2701</div>
2702
2703<!-- _______________________________________________________________________ -->
2704<div class="doc_subsubsection">
2705 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2706</div>
2707
2708<div class="doc_text">
2709
2710<h5>Syntax:</h5>
2711<pre>
Chris Lattnerfcf39d42006-01-13 01:20:27 +0000[diff] [blame^]2712 declare sbyte *%llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2713</pre>
2714
2715<h5>Overview:</h5>
2716
2717<p>
2718The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2719indicating the return address of the current function or one of its callers.
2720</p>
2721
2722<h5>Arguments:</h5>
2723
2724<p>
2725The argument to this intrinsic indicates which function to return the address
2726for. Zero indicates the calling function, one indicates its caller, etc. The
2727argument is <b>required</b> to be a constant integer value.
2728</p>
2729
2730<h5>Semantics:</h5>
2731
2732<p>
2733The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2734the return address of the specified call frame, or zero if it cannot be
2735identified. The value returned by this intrinsic is likely to be incorrect or 0
2736for arguments other than zero, so it should only be used for debugging purposes.
2737</p>
2738
2739<p>
2740Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]2741aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2742source-language caller.
2743</p>
2744</div>
2745
2746
2747<!-- _______________________________________________________________________ -->
2748<div class="doc_subsubsection">
2749 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2750</div>
2751
2752<div class="doc_text">
2753
2754<h5>Syntax:</h5>
2755<pre>
Chris Lattnerfcf39d42006-01-13 01:20:27 +0000[diff] [blame^]2756 declare sbyte *%llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2757</pre>
2758
2759<h5>Overview:</h5>
2760
2761<p>
2762The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2763pointer value for the specified stack frame.
2764</p>
2765
2766<h5>Arguments:</h5>
2767
2768<p>
2769The argument to this intrinsic indicates which function to return the frame
2770pointer for. Zero indicates the calling function, one indicates its caller,
2771etc. The argument is <b>required</b> to be a constant integer value.
2772</p>
2773
2774<h5>Semantics:</h5>
2775
2776<p>
2777The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2778the frame address of the specified call frame, or zero if it cannot be
2779identified. The value returned by this intrinsic is likely to be incorrect or 0
2780for arguments other than zero, so it should only be used for debugging purposes.
2781</p>
2782
2783<p>
2784Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]2785aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]2786source-language caller.
2787</p>
2788</div>
2789
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2790<!-- _______________________________________________________________________ -->
2791<div class="doc_subsubsection">
2792 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
2793</div>
2794
2795<div class="doc_text">
2796
2797<h5>Syntax:</h5>
2798<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2799 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
2800 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2801</pre>
2802
2803<h5>Overview:</h5>
2804
2805
2806<p>
2807The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2808a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
2809no
2810effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]2811characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2812</p>
2813
2814<h5>Arguments:</h5>
2815
2816<p>
2817<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
2818determining if the fetch should be for a read (0) or write (1), and
2819<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]2820locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2821<tt>locality</tt> arguments must be constant integers.
2822</p>
2823
2824<h5>Semantics:</h5>
2825
2826<p>
2827This intrinsic does not modify the behavior of the program. In particular,
2828prefetches cannot trap and do not produce a value. On targets that support this
2829intrinsic, the prefetch can provide hints to the processor cache for better
2830performance.
2831</p>
2832
2833</div>
2834
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2835<!-- _______________________________________________________________________ -->
2836<div class="doc_subsubsection">
2837 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
2838</div>
2839
2840<div class="doc_text">
2841
2842<h5>Syntax:</h5>
2843<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2844 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2845</pre>
2846
2847<h5>Overview:</h5>
2848
2849
2850<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2851The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
2852(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2853code to simulators and other tools. The method is target specific, but it is
2854expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]2855The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnerd07c3f42005-11-15 06:07:55 +0000[diff] [blame]2856after optimizations. It is possible that the presence of a marker will inhibit
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2857optimizations. The intended use is to be inserted after optmizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2858correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]2859</p>
2860
2861<h5>Arguments:</h5>
2862
2863<p>
2864<tt>id</tt> is a numerical id identifying the marker.
2865</p>
2866
2867<h5>Semantics:</h5>
2868
2869<p>
2870This intrinsic does not modify the behavior of the program. Backends that do not
2871support this intrinisic may ignore it.
2872</p>
2873
2874</div>
2875
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]2876<!-- _______________________________________________________________________ -->
2877<div class="doc_subsubsection">
2878 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
2879</div>
2880
2881<div class="doc_text">
2882
2883<h5>Syntax:</h5>
2884<pre>
2885 declare ulong %llvm.readcyclecounter( )
2886</pre>
2887
2888<h5>Overview:</h5>
2889
2890
2891<p>
2892The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
2893counter register (or similar low latency, high accuracy clocks) on those targets
2894that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
2895As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
2896should only be used for small timings.
2897</p>
2898
2899<h5>Semantics:</h5>
2900
2901<p>
2902When directly supported, reading the cycle counter should not modify any memory.
2903Implementations are allowed to either return a application specific value or a
2904system wide value. On backends without support, this is lowered to a constant 0.
2905</p>
2906
2907</div>
2908
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]2909
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2910<!-- ======================================================================= -->
2911<div class="doc_subsection">
2912 <a name="int_os">Operating System Intrinsics</a>
2913</div>
2914
2915<div class="doc_text">
2916<p>
2917These intrinsics are provided by LLVM to support the implementation of
2918operating system level code.
2919</p>
2920
2921</div>
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]2922
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2923<!-- _______________________________________________________________________ -->
2924<div class="doc_subsubsection">
2925 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2926</div>
2927
2928<div class="doc_text">
2929
2930<h5>Syntax:</h5>
2931<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]2932 declare &lt;integer type&gt; %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2933</pre>
2934
2935<h5>Overview:</h5>
2936
2937<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2938The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2939I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2940</p>
2941
2942<h5>Arguments:</h5>
2943
2944<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2945The argument to this intrinsic indicates the hardware I/O address from which
2946to read the data. The address is in the hardware I/O address namespace (as
2947opposed to being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2948</p>
2949
2950<h5>Semantics:</h5>
2951
2952<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2953The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2954specified by <i>address</i> and returns the value. The address and return
2955value must be integers, but the size is dependent upon the platform upon which
2956the program is code generated. For example, on x86, the address must be an
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]2957unsigned 16-bit value, and the return value must be 8, 16, or 32 bits.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2958</p>
2959
2960</div>
2961
2962<!-- _______________________________________________________________________ -->
2963<div class="doc_subsubsection">
2964 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2965</div>
2966
2967<div class="doc_text">
2968
2969<h5>Syntax:</h5>
2970<pre>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]2971 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
2972 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
2973 &lt;integer type&gt; &lt;address&gt;)
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2974</pre>
2975
2976<h5>Overview:</h5>
2977
2978<p>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]2979The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2980I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2981</p>
2982
2983<h5>Arguments:</h5>
2984
2985<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2986The first argument is the value to write to the I/O port.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2987</p>
2988
2989<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]2990The second argument indicates the hardware I/O address to which data should be
2991written. The address is in the hardware I/O address namespace (as opposed to
2992being a memory location for memory mapped I/O).
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]2993</p>
2994
2995<h5>Semantics:</h5>
2996
2997<p>
2998The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2999specified by <i>address</i>. The address and value must be integers, but the
3000size is dependent upon the platform upon which the program is code generated.
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]3001For example, on x86, the address must be an unsigned 16-bit value, and the
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]3002value written must be 8, 16, or 32 bits in length.
John Criswellcfd3bac2004-04-09 15:23:37 +0000[diff] [blame]3003</p>
3004
3005</div>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3006
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3007<!-- _______________________________________________________________________ -->
3008<div class="doc_subsubsection">
3009 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
3010</div>
3011
3012<div class="doc_text">
3013
3014<h5>Syntax:</h5>
3015<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3016 declare &lt;result&gt; %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3017</pre>
3018
3019<h5>Overview:</h5>
3020
3021<p>
3022The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
3023address.
3024</p>
3025
3026<h5>Arguments:</h5>
3027
3028<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3029The argument to this intrinsic is a pointer indicating the memory address from
3030which to read the data. The data must be a
3031<a href="#t_firstclass">first class</a> type.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3032</p>
3033
3034<h5>Semantics:</h5>
3035
3036<p>
3037The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3038location specified by <i>pointer</i> and returns the value. The argument must
3039be a pointer, and the return value must be a
3040<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]3041may not support I/O on all first class types. For example, 32-bit processors
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3042may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3043</p>
3044
3045<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3046This intrinsic enforces an in-order memory model for llvm.readio and
3047llvm.writeio calls on machines that use dynamic scheduling. Dynamically
3048scheduled processors may execute loads and stores out of order, re-ordering at
3049run time accesses to memory mapped I/O registers. Using these intrinsics
3050ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3051</p>
3052
3053</div>
3054
3055<!-- _______________________________________________________________________ -->
3056<div class="doc_subsubsection">
3057 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
3058</div>
3059
3060<div class="doc_text">
3061
3062<h5>Syntax:</h5>
3063<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3064 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]3065</pre>
3066
3067<h5>Overview:</h5>
3068
3069<p>
3070The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
3071mapped I/O address.
3072</p>
3073
3074<h5>Arguments:</h5>
3075
3076<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3077The first argument is the value to write to the memory mapped I/O location.
3078The second argument is a pointer indicating the memory address to which the
3079data should be written.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3080</p>
3081
3082<h5>Semantics:</h5>
3083
3084<p>
3085The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3086I/O address specified by <i>pointer</i>. The value must be a
3087<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]3088may not support I/O on all first class types. For example, 32-bit processors
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3089may only support I/O on data types that are 32 bits or less.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3090</p>
3091
3092<p>
John Criswell96db6fc2004-04-12 16:33:19 +0000[diff] [blame]3093This intrinsic enforces an in-order memory model for llvm.readio and
3094llvm.writeio calls on machines that use dynamic scheduling. Dynamically
3095scheduled processors may execute loads and stores out of order, re-ordering at
3096run time accesses to memory mapped I/O registers. Using these intrinsics
3097ensures that accesses to memory mapped I/O registers occur in program order.
John Criswell183402a2004-04-12 15:02:16 +0000[diff] [blame]3098</p>
3099
3100</div>
3101
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3102<!-- ======================================================================= -->
3103<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3104 <a name="int_libc">Standard C Library Intrinsics</a>
3105</div>
3106
3107<div class="doc_text">
3108<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3109LLVM provides intrinsics for a few important standard C library functions.
3110These intrinsics allow source-language front-ends to pass information about the
3111alignment of the pointer arguments to the code generator, providing opportunity
3112for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3113</p>
3114
3115</div>
3116
3117<!-- _______________________________________________________________________ -->
3118<div class="doc_subsubsection">
3119 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
3120</div>
3121
3122<div class="doc_text">
3123
3124<h5>Syntax:</h5>
3125<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3126 declare void %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3127 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3128</pre>
3129
3130<h5>Overview:</h5>
3131
3132<p>
3133The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3134location to the destination location.
3135</p>
3136
3137<p>
3138Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
3139does not return a value, and takes an extra alignment argument.
3140</p>
3141
3142<h5>Arguments:</h5>
3143
3144<p>
3145The first argument is a pointer to the destination, the second is a pointer to
3146the source. The third argument is an (arbitrarily sized) integer argument
3147specifying the number of bytes to copy, and the fourth argument is the alignment
3148of the source and destination locations.
3149</p>
3150
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]3151<p>
3152If the call to this intrinisic has an alignment value that is not 0 or 1, then
3153the caller guarantees that the size of the copy is a multiple of the alignment
3154and that both the source and destination pointers are aligned to that boundary.
3155</p>
3156
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3157<h5>Semantics:</h5>
3158
3159<p>
3160The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3161location to the destination location, which are not allowed to overlap. It
3162copies "len" bytes of memory over. If the argument is known to be aligned to
3163some boundary, this can be specified as the fourth argument, otherwise it should
3164be set to 0 or 1.
3165</p>
3166</div>
3167
3168
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3169<!-- _______________________________________________________________________ -->
3170<div class="doc_subsubsection">
3171 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3172</div>
3173
3174<div class="doc_text">
3175
3176<h5>Syntax:</h5>
3177<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3178 declare void %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3179 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3180</pre>
3181
3182<h5>Overview:</h5>
3183
3184<p>
3185The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
3186location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
3187intrinsic but allows the two memory locations to overlap.
3188</p>
3189
3190<p>
3191Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
3192does not return a value, and takes an extra alignment argument.
3193</p>
3194
3195<h5>Arguments:</h5>
3196
3197<p>
3198The first argument is a pointer to the destination, the second is a pointer to
3199the source. The third argument is an (arbitrarily sized) integer argument
3200specifying the number of bytes to copy, and the fourth argument is the alignment
3201of the source and destination locations.
3202</p>
3203
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]3204<p>
3205If the call to this intrinisic has an alignment value that is not 0 or 1, then
3206the caller guarantees that the size of the copy is a multiple of the alignment
3207and that both the source and destination pointers are aligned to that boundary.
3208</p>
3209
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]3210<h5>Semantics:</h5>
3211
3212<p>
3213The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
3214location to the destination location, which may overlap. It
3215copies "len" bytes of memory over. If the argument is known to be aligned to
3216some boundary, this can be specified as the fourth argument, otherwise it should
3217be set to 0 or 1.
3218</p>
3219</div>
3220
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3221
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3222<!-- _______________________________________________________________________ -->
3223<div class="doc_subsubsection">
3224 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
3225</div>
3226
3227<div class="doc_text">
3228
3229<h5>Syntax:</h5>
3230<pre>
Reid Spencerd4622352005-04-26 20:41:16 +0000[diff] [blame]3231 declare void %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3232 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3233</pre>
3234
3235<h5>Overview:</h5>
3236
3237<p>
3238The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
3239byte value.
3240</p>
3241
3242<p>
3243Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3244does not return a value, and takes an extra alignment argument.
3245</p>
3246
3247<h5>Arguments:</h5>
3248
3249<p>
3250The first argument is a pointer to the destination to fill, the second is the
3251byte value to fill it with, the third argument is an (arbitrarily sized) integer
3252argument specifying the number of bytes to fill, and the fourth argument is the
3253known alignment of destination location.
3254</p>
3255
3256<p>
3257If the call to this intrinisic has an alignment value that is not 0 or 1, then
3258the caller guarantees that the size of the copy is a multiple of the alignment
3259and that the destination pointer is aligned to that boundary.
3260</p>
3261
3262<h5>Semantics:</h5>
3263
3264<p>
3265The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
3266destination location. If the argument is known to be aligned to some boundary,
3267this can be specified as the fourth argument, otherwise it should be set to 0 or
32681.
3269</p>
3270</div>
3271
3272
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]3273<!-- _______________________________________________________________________ -->
3274<div class="doc_subsubsection">
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]3275 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
3276</div>
3277
3278<div class="doc_text">
3279
3280<h5>Syntax:</h5>
3281<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3282 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]3283</pre>
3284
3285<h5>Overview:</h5>
3286
3287<p>
3288The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
3289specified floating point values is a NAN.
3290</p>
3291
3292<h5>Arguments:</h5>
3293
3294<p>
3295The arguments are floating point numbers of the same type.
3296</p>
3297
3298<h5>Semantics:</h5>
3299
3300<p>
3301If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3302false.
3303</p>
3304</div>
3305
3306
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]3307<!-- _______________________________________________________________________ -->
3308<div class="doc_subsubsection">
3309 <a name="i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a>
3310</div>
3311
3312<div class="doc_text">
3313
3314<h5>Syntax:</h5>
3315<pre>
3316 declare &lt;float or double&gt; %llvm.sqrt(&lt;float or double&gt; Val)
3317</pre>
3318
3319<h5>Overview:</h5>
3320
3321<p>
3322The '<tt>llvm.sqrt</tt>' intrinsic returns the sqrt of the specified operand,
3323returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
3324<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
3325negative numbers (which allows for better optimization).
3326</p>
3327
3328<h5>Arguments:</h5>
3329
3330<p>
3331The argument and return value are floating point numbers of the same type.
3332</p>
3333
3334<h5>Semantics:</h5>
3335
3336<p>
3337This function returns the sqrt of the specified operand if it is a positive
3338floating point number.
3339</p>
3340</div>
3341
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3342<!-- ======================================================================= -->
3343<div class="doc_subsection">
3344 <a name="int_count">Bit Counting Intrinsics</a>
3345</div>
3346
3347<div class="doc_text">
3348<p>
3349LLVM provides intrinsics for a few important bit counting operations.
3350These allow efficient code generation for some algorithms.
3351</p>
3352
3353</div>
3354
3355<!-- _______________________________________________________________________ -->
3356<div class="doc_subsubsection">
3357 <a name="int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic</a>
3358</div>
3359
3360<div class="doc_text">
3361
3362<h5>Syntax:</h5>
3363<pre>
3364 declare int %llvm.ctpop(int &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3365</pre>
3366
3367<h5>Overview:</h5>
3368
3369<p>
3370The '<tt>llvm.ctpop</tt>' intrinsic counts the number of ones in a variable.
3371</p>
3372
3373<h5>Arguments:</h5>
3374
3375<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3376The only argument is the value to be counted. The argument may be of any
3377integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3378</p>
3379
3380<h5>Semantics:</h5>
3381
3382<p>
3383The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3384</p>
3385</div>
3386
3387<!-- _______________________________________________________________________ -->
3388<div class="doc_subsubsection">
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3389 <a name="int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic</a>
3390</div>
3391
3392<div class="doc_text">
3393
3394<h5>Syntax:</h5>
3395<pre>
3396 declare int %llvm.ctlz(int &lt;src&gt;)
3397
3398</pre>
3399
3400<h5>Overview:</h5>
3401
3402<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3403The '<tt>llvm.ctlz</tt>' intrinsic counts the number of leading zeros in a
3404variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3405</p>
3406
3407<h5>Arguments:</h5>
3408
3409<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]3410The only argument is the value to be counted. The argument may be of any
3411integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3412</p>
3413
3414<h5>Semantics:</h5>
3415
3416<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3417The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
3418in a variable. If the src == 0 then the result is the size in bits of the type
3419of src. For example, <tt>llvm.cttz(int 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]3420</p>
3421</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]3422
3423
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3424
3425<!-- _______________________________________________________________________ -->
3426<div class="doc_subsubsection">
3427 <a name="int_cttz">'<tt>llvm.cttz</tt>' Intrinsic</a>
3428</div>
3429
3430<div class="doc_text">
3431
3432<h5>Syntax:</h5>
3433<pre>
3434 declare int %llvm.cttz(int &lt;src&gt;)
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]3435</pre>
3436
3437<h5>Overview:</h5>
3438
3439<p>
3440The '<tt>llvm.cttz</tt>' intrinsic counts the number of trailing zeros.
3441</p>
3442
3443<h5>Arguments:</h5>
3444
3445<p>
3446The only argument is the value to be counted. The argument may be of any
3447integer type. The return type must match the argument type.
3448</p>
3449
3450<h5>Semantics:</h5>
3451
3452<p>
3453The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
3454in a variable. If the src == 0 then the result is the size in bits of the type
3455of src. For example, <tt>llvm.cttz(2) = 1</tt>.
3456</p>
3457</div>
3458
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3459<!-- ======================================================================= -->
3460<div class="doc_subsection">
3461 <a name="int_debugger">Debugger Intrinsics</a>
3462</div>
3463
3464<div class="doc_text">
3465<p>
3466The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3467are described in the <a
3468href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3469Debugging</a> document.
3470</p>
3471</div>
3472
3473
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3474<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3475<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]3476<address>
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3481
3482 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
3483 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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