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5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman76307852003-11-08 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 Lattner6af02f32004-12-09 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 Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattner6af02f32004-12-09 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 Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]29 <li><a href="#typesystem">Type System</a>
30 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]31 <li><a href="#t_primitive">Primitive Types</a>
32 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]33 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]34 </ol>
35 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]36 <li><a href="#t_derived">Derived Types</a>
37 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]38 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 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 Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]41 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]42 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]43 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]44 </ol>
45 </li>
46 </ol>
47 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]48 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 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 Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]56 </li>
Chris Lattner2f7c9632001-06-06 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 Lattner48b383b02003-11-25 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 Brukman76307852003-11-08 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 Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]65 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]66 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]67 </ol>
68 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]69 <li><a href="#binaryops">Binary Operations</a>
70 <ol>
Chris Lattner48b383b02003-11-25 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 Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]76 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]77 </ol>
78 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]79 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
80 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]81 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]82 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 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 Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]86 </ol>
87 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]88 <li><a href="#memoryops">Memory Access Operations</a>
89 <ol>
Chris Lattner48b383b02003-11-25 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 Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]98 <li><a href="#otherops">Other Operations</a>
99 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]100 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]101 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]102 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Robert Bocchinob5f210f2006-01-05 17:37:02 +0000[diff] [blame]103 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]104 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]105 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]106 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]107 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]108 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]109 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]110 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]111 <ol>
Chris Lattner48b383b02003-11-25 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 Lattner757528b0b2004-05-23 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 Lattner3649c3a2004-02-14 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 Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]130 <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
131 <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]132 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]133 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]134 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]135 </ol>
136 </li>
137 <li><a href="#int_os">Operating System Intrinsics</a>
138 <ol>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]139 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
140 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]141 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
142 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]143 </ol>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]144 <li><a href="#int_libc">Standard C Library Intrinsics</a>
145 <ol>
146 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]147 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]148 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos9d740622004-06-12 19:19:14 +0000[diff] [blame]149 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]150 <li><a href="#i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a></li>
151
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]152 </ol>
153 </li>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]154 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]155 <ol>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]156 <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]157 <li><a href="#int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]158 <li><a href="#int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic </a></li>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]159 <li><a href="#int_cttz">'<tt>llvm.cttz</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]160 </ol>
161 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]162 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]163 </ol>
164 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]165</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]166
167<div class="doc_author">
168 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
169 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]170</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]171
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]172<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]173<div class="doc_section"> <a name="abstract">Abstract </a></div>
174<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]175
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]176<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]177<p>This document is a reference manual for the LLVM assembly language.
178LLVM is an SSA based representation that provides type safety,
179low-level operations, flexibility, and the capability of representing
180'all' high-level languages cleanly. It is the common code
181representation used throughout all phases of the LLVM compilation
182strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]183</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]184
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]185<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]186<div class="doc_section"> <a name="introduction">Introduction</a> </div>
187<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]188
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]189<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]190
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]191<p>The LLVM code representation is designed to be used in three
192different forms: as an in-memory compiler IR, as an on-disk bytecode
193representation (suitable for fast loading by a Just-In-Time compiler),
194and as a human readable assembly language representation. This allows
195LLVM to provide a powerful intermediate representation for efficient
196compiler transformations and analysis, while providing a natural means
197to debug and visualize the transformations. The three different forms
198of LLVM are all equivalent. This document describes the human readable
199representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]200
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]201<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]202while being expressive, typed, and extensible at the same time. It
203aims to be a "universal IR" of sorts, by being at a low enough level
204that high-level ideas may be cleanly mapped to it (similar to how
205microprocessors are "universal IR's", allowing many source languages to
206be mapped to them). By providing type information, LLVM can be used as
207the target of optimizations: for example, through pointer analysis, it
208can be proven that a C automatic variable is never accessed outside of
209the current function... allowing it to be promoted to a simple SSA
210value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]211
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]212</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]213
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]214<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]215<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]216
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]217<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]218
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]219<p>It is important to note that this document describes 'well formed'
220LLVM assembly language. There is a difference between what the parser
221accepts and what is considered 'well formed'. For example, the
222following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]223
224<pre>
225 %x = <a href="#i_add">add</a> int 1, %x
226</pre>
227
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]228<p>...because the definition of <tt>%x</tt> does not dominate all of
229its uses. The LLVM infrastructure provides a verification pass that may
230be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]231automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]232the optimizer before it outputs bytecode. The violations pointed out
233by the verifier pass indicate bugs in transformation passes or input to
234the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]235
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]236<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]237
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]238<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]239<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]240<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]241
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]242<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]243
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]244<p>LLVM uses three different forms of identifiers, for different
245purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]246
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]247<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]248 <li>Named values are represented as a string of characters with a '%' prefix.
249 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
250 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
251 Identifiers which require other characters in their names can be surrounded
252 with quotes. In this way, anything except a <tt>"</tt> character can be used
253 in a name.</li>
254
255 <li>Unnamed values are represented as an unsigned numeric value with a '%'
256 prefix. For example, %12, %2, %44.</li>
257
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]258 <li>Constants, which are described in a <a href="#constants">section about
259 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]260</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]261
262<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
263don't need to worry about name clashes with reserved words, and the set of
264reserved words may be expanded in the future without penalty. Additionally,
265unnamed identifiers allow a compiler to quickly come up with a temporary
266variable without having to avoid symbol table conflicts.</p>
267
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]268<p>Reserved words in LLVM are very similar to reserved words in other
269languages. There are keywords for different opcodes ('<tt><a
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]270href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
271href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
272href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
273and others. These reserved words cannot conflict with variable names, because
274none of them start with a '%' character.</p>
275
276<p>Here is an example of LLVM code to multiply the integer variable
277'<tt>%X</tt>' by 8:</p>
278
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]279<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]280
281<pre>
282 %result = <a href="#i_mul">mul</a> uint %X, 8
283</pre>
284
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]285<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]286
287<pre>
288 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
289</pre>
290
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]291<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]292
293<pre>
294 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
295 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
296 %result = <a href="#i_add">add</a> uint %1, %1
297</pre>
298
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]299<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
300important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]301
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]302<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]303
304 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
305 line.</li>
306
307 <li>Unnamed temporaries are created when the result of a computation is not
308 assigned to a named value.</li>
309
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]310 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]311
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]312</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]313
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]314<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]315demonstrating instructions, we will follow an instruction with a comment that
316defines the type and name of value produced. Comments are shown in italic
317text.</p>
318
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]319</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]320
321<!-- *********************************************************************** -->
322<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
323<!-- *********************************************************************** -->
324
325<!-- ======================================================================= -->
326<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
327</div>
328
329<div class="doc_text">
330
331<p>LLVM programs are composed of "Module"s, each of which is a
332translation unit of the input programs. Each module consists of
333functions, global variables, and symbol table entries. Modules may be
334combined together with the LLVM linker, which merges function (and
335global variable) definitions, resolves forward declarations, and merges
336symbol table entries. Here is an example of the "hello world" module:</p>
337
338<pre><i>; Declare the string constant as a global constant...</i>
339<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
340 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
341
342<i>; External declaration of the puts function</i>
343<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
344
345<i>; Definition of main function</i>
346int %main() { <i>; int()* </i>
347 <i>; Convert [13x sbyte]* to sbyte *...</i>
348 %cast210 = <a
349 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
350
351 <i>; Call puts function to write out the string to stdout...</i>
352 <a
353 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
354 <a
355 href="#i_ret">ret</a> int 0<br>}<br></pre>
356
357<p>This example is made up of a <a href="#globalvars">global variable</a>
358named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
359function, and a <a href="#functionstructure">function definition</a>
360for "<tt>main</tt>".</p>
361
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]362<p>In general, a module is made up of a list of global values,
363where both functions and global variables are global values. Global values are
364represented by a pointer to a memory location (in this case, a pointer to an
365array of char, and a pointer to a function), and have one of the following <a
366href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]367
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]368</div>
369
370<!-- ======================================================================= -->
371<div class="doc_subsection">
372 <a name="linkage">Linkage Types</a>
373</div>
374
375<div class="doc_text">
376
377<p>
378All Global Variables and Functions have one of the following types of linkage:
379</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]380
381<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]382
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]383 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]384
385 <dd>Global values with internal linkage are only directly accessible by
386 objects in the current module. In particular, linking code into a module with
387 an internal global value may cause the internal to be renamed as necessary to
388 avoid collisions. Because the symbol is internal to the module, all
389 references can be updated. This corresponds to the notion of the
390 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]391 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]392
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]393 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]394
395 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
396 the twist that linking together two modules defining the same
397 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
398 is typically used to implement inline functions. Unreferenced
399 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]400 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]401
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]402 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]403
404 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
405 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
406 used to implement constructs in C such as "<tt>int X;</tt>" at global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]407 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]408
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]409 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]410
411 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
412 pointer to array type. When two global variables with appending linkage are
413 linked together, the two global arrays are appended together. This is the
414 LLVM, typesafe, equivalent of having the system linker append together
415 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]416 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]417
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]418 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]419
420 <dd>If none of the above identifiers are used, the global is externally
421 visible, meaning that it participates in linkage and can be used to resolve
422 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]423 </dd>
424</dl>
425
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]426<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
427variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
428variable and was linked with this one, one of the two would be renamed,
429preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
430external (i.e., lacking any linkage declarations), they are accessible
431outside of the current module. It is illegal for a function <i>declaration</i>
432to have any linkage type other than "externally visible".</a></p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]433
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]434</div>
435
436<!-- ======================================================================= -->
437<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]438 <a name="callingconv">Calling Conventions</a>
439</div>
440
441<div class="doc_text">
442
443<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
444and <a href="#i_invoke">invokes</a> can all have an optional calling convention
445specified for the call. The calling convention of any pair of dynamic
446caller/callee must match, or the behavior of the program is undefined. The
447following calling conventions are supported by LLVM, and more may be added in
448the future:</p>
449
450<dl>
451 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
452
453 <dd>This calling convention (the default if no other calling convention is
454 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]455 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]456 prototype and implemented declaration of the function (as does normal C).
457 </dd>
458
459 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
460
461 <dd>This calling convention attempts to make calls as fast as possible
462 (e.g. by passing things in registers). This calling convention allows the
463 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]464 without having to conform to an externally specified ABI. Implementations of
465 this convention should allow arbitrary tail call optimization to be supported.
466 This calling convention does not support varargs and requires the prototype of
467 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]468 </dd>
469
470 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
471
472 <dd>This calling convention attempts to make code in the caller as efficient
473 as possible under the assumption that the call is not commonly executed. As
474 such, these calls often preserve all registers so that the call does not break
475 any live ranges in the caller side. This calling convention does not support
476 varargs and requires the prototype of all callees to exactly match the
477 prototype of the function definition.
478 </dd>
479
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]480 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]481
482 <dd>Any calling convention may be specified by number, allowing
483 target-specific calling conventions to be used. Target specific calling
484 conventions start at 64.
485 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]486</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]487
488<p>More calling conventions can be added/defined on an as-needed basis, to
489support pascal conventions or any other well-known target-independent
490convention.</p>
491
492</div>
493
494<!-- ======================================================================= -->
495<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]496 <a name="globalvars">Global Variables</a>
497</div>
498
499<div class="doc_text">
500
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]501<p>Global variables define regions of memory allocated at compilation time
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]502instead of run-time. Global variables may optionally be initialized, may have
503an explicit section to be placed in, and may
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]504have an optional explicit alignment specified. A
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]505variable may be defined as a global "constant," which indicates that the
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]506contents of the variable will <b>never</b> be modified (enabling better
507optimization, allowing the global data to be placed in the read-only section of
508an executable, etc). Note that variables that need runtime initialization
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]509cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]510
511<p>
512LLVM explicitly allows <em>declarations</em> of global variables to be marked
513constant, even if the final definition of the global is not. This capability
514can be used to enable slightly better optimization of the program, but requires
515the language definition to guarantee that optimizations based on the
516'constantness' are valid for the translation units that do not include the
517definition.
518</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]519
520<p>As SSA values, global variables define pointer values that are in
521scope (i.e. they dominate) all basic blocks in the program. Global
522variables always define a pointer to their "content" type because they
523describe a region of memory, and all memory objects in LLVM are
524accessed through pointers.</p>
525
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]526<p>LLVM allows an explicit section to be specified for globals. If the target
527supports it, it will emit globals to the section specified.</p>
528
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]529<p>An explicit alignment may be specified for a global. If not present, or if
530the alignment is set to zero, the alignment of the global is set by the target
531to whatever it feels convenient. If an explicit alignment is specified, the
532global is forced to have at least that much alignment. All alignments must be
533a power of 2.</p>
534
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]535</div>
536
537
538<!-- ======================================================================= -->
539<div class="doc_subsection">
540 <a name="functionstructure">Functions</a>
541</div>
542
543<div class="doc_text">
544
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]545<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
546type</a>, an optional <a href="#callingconv">calling convention</a>, a return
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]547type, a function name, a (possibly empty) argument list, an optional section,
548an optional alignment, an opening curly brace,
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]549a list of basic blocks, and a closing curly brace. LLVM function declarations
550are defined with the "<tt>declare</tt>" keyword, an optional <a
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]551href="#callingconv">calling convention</a>, a return type, a function name,
552a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]553
554<p>A function definition contains a list of basic blocks, forming the CFG for
555the function. Each basic block may optionally start with a label (giving the
556basic block a symbol table entry), contains a list of instructions, and ends
557with a <a href="#terminators">terminator</a> instruction (such as a branch or
558function return).</p>
559
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]560<p>The first basic block in a program is special in two ways: it is immediately
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]561executed on entrance to the function, and it is not allowed to have predecessor
562basic blocks (i.e. there can not be any branches to the entry block of a
563function). Because the block can have no predecessors, it also cannot have any
564<a href="#i_phi">PHI nodes</a>.</p>
565
566<p>LLVM functions are identified by their name and type signature. Hence, two
567functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]568considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]569appropriately.</p>
570
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]571<p>LLVM allows an explicit section to be specified for functions. If the target
572supports it, it will emit functions to the section specified.</p>
573
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]574<p>An explicit alignment may be specified for a function. If not present, or if
575the alignment is set to zero, the alignment of the function is set by the target
576to whatever it feels convenient. If an explicit alignment is specified, the
577function is forced to have at least that much alignment. All alignments must be
578a power of 2.</p>
579
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]580</div>
581
582
583
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]584<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]585<div class="doc_section"> <a name="typesystem">Type System</a> </div>
586<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]587
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]588<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]589
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]590<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]591intermediate representation. Being typed enables a number of
592optimizations to be performed on the IR directly, without having to do
593extra analyses on the side before the transformation. A strong type
594system makes it easier to read the generated code and enables novel
595analyses and transformations that are not feasible to perform on normal
596three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]597
598</div>
599
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]600<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]601<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]602<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]603<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]604system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]605
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]606<table class="layout">
607 <tr class="layout">
608 <td class="left">
609 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]610 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]611 <tr><th>Type</th><th>Description</th></tr>
612 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]613 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
614 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
615 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
616 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
617 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]618 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]619 </tbody>
620 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]621 </td>
622 <td class="right">
623 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]624 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]625 <tr><th>Type</th><th>Description</th></tr>
626 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]627 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
628 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
629 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
630 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
631 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]632 </tbody>
633 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]634 </td>
635 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]636</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]637</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]638
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]639<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]640<div class="doc_subsubsection"> <a name="t_classifications">Type
641Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]642<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]643<p>These different primitive types fall into a few useful
644classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]645
646<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]647 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]648 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]649 <tr>
650 <td><a name="t_signed">signed</a></td>
651 <td><tt>sbyte, short, int, long, float, double</tt></td>
652 </tr>
653 <tr>
654 <td><a name="t_unsigned">unsigned</a></td>
655 <td><tt>ubyte, ushort, uint, ulong</tt></td>
656 </tr>
657 <tr>
658 <td><a name="t_integer">integer</a></td>
659 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
660 </tr>
661 <tr>
662 <td><a name="t_integral">integral</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]663 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
664 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]665 </tr>
666 <tr>
667 <td><a name="t_floating">floating point</a></td>
668 <td><tt>float, double</tt></td>
669 </tr>
670 <tr>
671 <td><a name="t_firstclass">first class</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]672 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
673 float, double, <a href="#t_pointer">pointer</a>,
674 <a href="#t_packed">packed</a></tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]675 </tr>
676 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]677</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]678
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]679<p>The <a href="#t_firstclass">first class</a> types are perhaps the
680most important. Values of these types are the only ones which can be
681produced by instructions, passed as arguments, or used as operands to
682instructions. This means that all structures and arrays must be
683manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]684</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]685
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]686<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]687<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]688
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]689<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]690
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]691<p>The real power in LLVM comes from the derived types in the system.
692This is what allows a programmer to represent arrays, functions,
693pointers, and other useful types. Note that these derived types may be
694recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]695
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]696</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]697
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]698<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]699<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]700
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]701<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]702
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]703<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]704
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]705<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]706sequentially in memory. The array type requires a size (number of
707elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]708
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]709<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]710
711<pre>
712 [&lt;# elements&gt; x &lt;elementtype&gt;]
713</pre>
714
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]715<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]716be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]717
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]718<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]719<table class="layout">
720 <tr class="layout">
721 <td class="left">
722 <tt>[40 x int ]</tt><br/>
723 <tt>[41 x int ]</tt><br/>
724 <tt>[40 x uint]</tt><br/>
725 </td>
726 <td class="left">
727 Array of 40 integer values.<br/>
728 Array of 41 integer values.<br/>
729 Array of 40 unsigned integer values.<br/>
730 </td>
731 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]732</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]733<p>Here are some examples of multidimensional arrays:</p>
734<table class="layout">
735 <tr class="layout">
736 <td class="left">
737 <tt>[3 x [4 x int]]</tt><br/>
738 <tt>[12 x [10 x float]]</tt><br/>
739 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
740 </td>
741 <td class="left">
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]742 3x4 array of integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]743 12x10 array of single precision floating point values.<br/>
744 2x3x4 array of unsigned integer values.<br/>
745 </td>
746 </tr>
747</table>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]748
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]749<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
750length array. Normally, accesses past the end of an array are undefined in
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]751LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
752As a special case, however, zero length arrays are recognized to be variable
753length. This allows implementation of 'pascal style arrays' with the LLVM
754type "{ int, [0 x float]}", for example.</p>
755
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]756</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]757
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]758<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]759<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]760<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]761<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]762<p>The function type can be thought of as a function signature. It
763consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]764Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]765(which are structures of pointers to functions), for indirect function
766calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]767<p>
768The return type of a function type cannot be an aggregate type.
769</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]770<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]771<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]772<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]773specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]774which indicates that the function takes a variable number of arguments.
775Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]776 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]777<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]778<table class="layout">
779 <tr class="layout">
780 <td class="left">
781 <tt>int (int)</tt> <br/>
782 <tt>float (int, int *) *</tt><br/>
783 <tt>int (sbyte *, ...)</tt><br/>
784 </td>
785 <td class="left">
786 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
787 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]788 <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]789 returning <tt>float</tt>.<br/>
790 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
791 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
792 the signature for <tt>printf</tt> in LLVM.<br/>
793 </td>
794 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]795</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]796
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]797</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]798<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]799<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]800<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]801<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]802<p>The structure type is used to represent a collection of data members
803together in memory. The packing of the field types is defined to match
804the ABI of the underlying processor. The elements of a structure may
805be any type that has a size.</p>
806<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
807and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
808field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
809instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]810<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]811<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]812<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]813<table class="layout">
814 <tr class="layout">
815 <td class="left">
816 <tt>{ int, int, int }</tt><br/>
817 <tt>{ float, int (int) * }</tt><br/>
818 </td>
819 <td class="left">
820 a triple of three <tt>int</tt> values<br/>
821 A pair, where the first element is a <tt>float</tt> and the second element
822 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
823 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
824 </td>
825 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]826</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]827</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]828
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]829<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]830<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]831<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]832<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]833<p>As in many languages, the pointer type represents a pointer or
834reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]835<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]836<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]837<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]838<table class="layout">
839 <tr class="layout">
840 <td class="left">
841 <tt>[4x int]*</tt><br/>
842 <tt>int (int *) *</tt><br/>
843 </td>
844 <td class="left">
845 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
846 four <tt>int</tt> values<br/>
847 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattner16fb0032005-02-19 02:22:14 +0000[diff] [blame]848 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]849 <tt>int</tt>.<br/>
850 </td>
851 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]852</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]853</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]854
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]855<!-- _______________________________________________________________________ -->
856<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]857<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]858
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]859<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]860
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]861<p>A packed type is a simple derived type that represents a vector
862of elements. Packed types are used when multiple primitive data
863are operated in parallel using a single instruction (SIMD).
864A packed type requires a size (number of
Chris Lattner330ce692005-11-10 01:44:22 +0000[diff] [blame]865elements) and an underlying primitive data type. Vectors must have a power
866of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]867considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]868
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]869<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]870
871<pre>
872 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
873</pre>
874
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]875<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]876be any integral or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]877
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]878<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]879
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]880<table class="layout">
881 <tr class="layout">
882 <td class="left">
883 <tt>&lt;4 x int&gt;</tt><br/>
884 <tt>&lt;8 x float&gt;</tt><br/>
885 <tt>&lt;2 x uint&gt;</tt><br/>
886 </td>
887 <td class="left">
888 Packed vector of 4 integer values.<br/>
889 Packed vector of 8 floating-point values.<br/>
890 Packed vector of 2 unsigned integer values.<br/>
891 </td>
892 </tr>
893</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]894</div>
895
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]896<!-- _______________________________________________________________________ -->
897<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
898<div class="doc_text">
899
900<h5>Overview:</h5>
901
902<p>Opaque types are used to represent unknown types in the system. This
903corresponds (for example) to the C notion of a foward declared structure type.
904In LLVM, opaque types can eventually be resolved to any type (not just a
905structure type).</p>
906
907<h5>Syntax:</h5>
908
909<pre>
910 opaque
911</pre>
912
913<h5>Examples:</h5>
914
915<table class="layout">
916 <tr class="layout">
917 <td class="left">
918 <tt>opaque</tt>
919 </td>
920 <td class="left">
921 An opaque type.<br/>
922 </td>
923 </tr>
924</table>
925</div>
926
927
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]928<!-- *********************************************************************** -->
929<div class="doc_section"> <a name="constants">Constants</a> </div>
930<!-- *********************************************************************** -->
931
932<div class="doc_text">
933
934<p>LLVM has several different basic types of constants. This section describes
935them all and their syntax.</p>
936
937</div>
938
939<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]940<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]941
942<div class="doc_text">
943
944<dl>
945 <dt><b>Boolean constants</b></dt>
946
947 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
948 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
949 </dd>
950
951 <dt><b>Integer constants</b></dt>
952
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]953 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]954 href="#t_integer">integer</a> type. Negative numbers may be used with signed
955 integer types.
956 </dd>
957
958 <dt><b>Floating point constants</b></dt>
959
960 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
961 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]962 notation (see below). Floating point constants must have a <a
963 href="#t_floating">floating point</a> type. </dd>
964
965 <dt><b>Null pointer constants</b></dt>
966
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]967 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]968 and must be of <a href="#t_pointer">pointer type</a>.</dd>
969
970</dl>
971
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]972<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]973of floating point constants. For example, the form '<tt>double
9740x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
9754.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]976(and the only time that they are generated by the disassembler) is when a
977floating point constant must be emitted but it cannot be represented as a
978decimal floating point number. For example, NaN's, infinities, and other
979special values are represented in their IEEE hexadecimal format so that
980assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]981
982</div>
983
984<!-- ======================================================================= -->
985<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
986</div>
987
988<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]989<p>Aggregate constants arise from aggregation of simple constants
990and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]991
992<dl>
993 <dt><b>Structure constants</b></dt>
994
995 <dd>Structure constants are represented with notation similar to structure
996 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]997 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
998 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
999 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1000 types of elements must match those specified by the type.
1001 </dd>
1002
1003 <dt><b>Array constants</b></dt>
1004
1005 <dd>Array constants are represented with notation similar to array type
1006 definitions (a comma separated list of elements, surrounded by square brackets
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1007 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1008 constants must have <a href="#t_array">array type</a>, and the number and
1009 types of elements must match those specified by the type.
1010 </dd>
1011
1012 <dt><b>Packed constants</b></dt>
1013
1014 <dd>Packed constants are represented with notation similar to packed type
1015 definitions (a comma separated list of elements, surrounded by
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1016 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; int 42,
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1017 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
1018 href="#t_packed">packed type</a>, and the number and types of elements must
1019 match those specified by the type.
1020 </dd>
1021
1022 <dt><b>Zero initialization</b></dt>
1023
1024 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1025 value to zero of <em>any</em> type, including scalar and aggregate types.
1026 This is often used to avoid having to print large zero initializers (e.g. for
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1027 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1028 initializers.
1029 </dd>
1030</dl>
1031
1032</div>
1033
1034<!-- ======================================================================= -->
1035<div class="doc_subsection">
1036 <a name="globalconstants">Global Variable and Function Addresses</a>
1037</div>
1038
1039<div class="doc_text">
1040
1041<p>The addresses of <a href="#globalvars">global variables</a> and <a
1042href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1043constants. These constants are explicitly referenced when the <a
1044href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1045href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1046file:</p>
1047
1048<pre>
1049 %X = global int 17
1050 %Y = global int 42
1051 %Z = global [2 x int*] [ int* %X, int* %Y ]
1052</pre>
1053
1054</div>
1055
1056<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1057<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1058<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1059 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1060 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1061 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1062
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1063 <p>Undefined values indicate to the compiler that the program is well defined
1064 no matter what value is used, giving the compiler more freedom to optimize.
1065 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1066</div>
1067
1068<!-- ======================================================================= -->
1069<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1070</div>
1071
1072<div class="doc_text">
1073
1074<p>Constant expressions are used to allow expressions involving other constants
1075to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1076href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1077that does not have side effects (e.g. load and call are not supported). The
1078following is the syntax for constant expressions:</p>
1079
1080<dl>
1081 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1082
1083 <dd>Cast a constant to another type.</dd>
1084
1085 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1086
1087 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1088 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1089 instruction, the index list may have zero or more indexes, which are required
1090 to make sense for the type of "CSTPTR".</dd>
1091
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1092 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1093
1094 <dd>Perform the <a href="#i_select">select operation</a> on
1095 constants.
1096
1097 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1098
1099 <dd>Perform the <a href="#i_extractelement">extractelement
1100 operation</a> on constants.
1101
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1102 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1103
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1104 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1105 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1106 binary</a> operations. The constraints on operands are the same as those for
1107 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1108 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1109</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1110</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1111
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1112<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1113<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1114<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1115
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1116<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1117
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1118<p>The LLVM instruction set consists of several different
1119classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1120instructions</a>, <a href="#binaryops">binary instructions</a>,
1121<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1122 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1123instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1124
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1125</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1126
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1127<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1128<div class="doc_subsection"> <a name="terminators">Terminator
1129Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1130
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1131<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1132
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1133<p>As mentioned <a href="#functionstructure">previously</a>, every
1134basic block in a program ends with a "Terminator" instruction, which
1135indicates which block should be executed after the current block is
1136finished. These terminator instructions typically yield a '<tt>void</tt>'
1137value: they produce control flow, not values (the one exception being
1138the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1139<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1140 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1141instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1142the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1143 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1144 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1145
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1146</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1147
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1148<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1149<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1150Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1151<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1152<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1153<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1154 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1155</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1156<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1157<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1158value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1159<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1160returns a value and then causes control flow, and one that just causes
1161control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1162<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1163<p>The '<tt>ret</tt>' instruction may return any '<a
1164 href="#t_firstclass">first class</a>' type. Notice that a function is
1165not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1166instruction inside of the function that returns a value that does not
1167match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1168<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1169<p>When the '<tt>ret</tt>' instruction is executed, control flow
1170returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1171 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1172the instruction after the call. If the caller was an "<a
1173 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1174at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1175returns a value, that value shall set the call or invoke instruction's
1176return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1177<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1178<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1179 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1180</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1181</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1182<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1183<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1184<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1185<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1186<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 Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1187</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1188<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1189<p>The '<tt>br</tt>' instruction is used to cause control flow to
1190transfer to a different basic block in the current function. There are
1191two forms of this instruction, corresponding to a conditional branch
1192and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1193<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1194<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1195single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1196unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1197value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1198<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1199<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1200argument is evaluated. If the value is <tt>true</tt>, control flows
1201to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1202control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1203<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1204<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
1205 href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1206</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1207<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1208<div class="doc_subsubsection">
1209 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1210</div>
1211
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1212<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1213<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1214
1215<pre>
1216 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1217</pre>
1218
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1219<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1220
1221<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1222several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1223instruction, allowing a branch to occur to one of many possible
1224destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1225
1226
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1227<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1228
1229<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1230comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1231an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1232table is not allowed to contain duplicate constant entries.</p>
1233
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1234<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1235
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1236<p>The <tt>switch</tt> instruction specifies a table of values and
1237destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1238table is searched for the given value. If the value is found, control flow is
1239transfered to the corresponding destination; otherwise, control flow is
1240transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1241
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1242<h5>Implementation:</h5>
1243
1244<p>Depending on properties of the target machine and the particular
1245<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1246ways. For example, it could be generated as a series of chained conditional
1247branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1248
1249<h5>Example:</h5>
1250
1251<pre>
1252 <i>; Emulate a conditional br instruction</i>
1253 %Val = <a href="#i_cast">cast</a> bool %value to int
1254 switch int %Val, label %truedest [int 0, label %falsedest ]
1255
1256 <i>; Emulate an unconditional br instruction</i>
1257 switch uint 0, label %dest [ ]
1258
1259 <i>; Implement a jump table:</i>
1260 switch uint %val, label %otherwise [ uint 0, label %onzero
1261 uint 1, label %onone
1262 uint 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1263</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1264</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1265
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1266<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1267<div class="doc_subsubsection">
1268 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1269</div>
1270
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1271<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1272
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1273<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1274
1275<pre>
1276 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1277 to label &lt;normal label&gt; except label &lt;exception label&gt;
1278</pre>
1279
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1280<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1281
1282<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1283function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1284'<tt>normal</tt>' label or the
1285'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1286"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1287"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1288href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1289continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1290
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1291<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1292
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1293<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1294
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1295<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1296 <li>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1297 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1298 convention</a> the call should use. If none is specified, the call defaults
1299 to using C calling conventions.
1300 </li>
1301 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1302 function value being invoked. In most cases, this is a direct function
1303 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1304 an arbitrary pointer to function value.
1305 </li>
1306
1307 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1308 function to be invoked. </li>
1309
1310 <li>'<tt>function args</tt>': argument list whose types match the function
1311 signature argument types. If the function signature indicates the function
1312 accepts a variable number of arguments, the extra arguments can be
1313 specified. </li>
1314
1315 <li>'<tt>normal label</tt>': the label reached when the called function
1316 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1317
1318 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1319 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1320
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1321</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1322
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1323<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1324
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1325<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1326href="#i_call">call</a></tt>' instruction in most regards. The primary
1327difference is that it establishes an association with a label, which is used by
1328the runtime library to unwind the stack.</p>
1329
1330<p>This instruction is used in languages with destructors to ensure that proper
1331cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1332exception. Additionally, this is important for implementation of
1333'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1334
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1335<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1336<pre>
1337 %retval = invoke int %Test(int 15) to label %Continue
1338 except label %TestCleanup <i>; {int}:retval set</i>
1339 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
1340 except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1341</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1342</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1343
1344
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1345<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1346
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1347<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1348Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1349
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1350<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1351
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1352<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1353<pre>
1354 unwind
1355</pre>
1356
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1357<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1358
1359<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1360at the first callee in the dynamic call stack which used an <a
1361href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1362primarily used to implement exception handling.</p>
1363
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1364<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1365
1366<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1367immediately halt. The dynamic call stack is then searched for the first <a
1368href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1369execution continues at the "exceptional" destination block specified by the
1370<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1371dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1372</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1373
1374<!-- _______________________________________________________________________ -->
1375
1376<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1377Instruction</a> </div>
1378
1379<div class="doc_text">
1380
1381<h5>Syntax:</h5>
1382<pre>
1383 unreachable
1384</pre>
1385
1386<h5>Overview:</h5>
1387
1388<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1389instruction is used to inform the optimizer that a particular portion of the
1390code is not reachable. This can be used to indicate that the code after a
1391no-return function cannot be reached, and other facts.</p>
1392
1393<h5>Semantics:</h5>
1394
1395<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1396</div>
1397
1398
1399
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1400<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1401<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1402<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1403<p>Binary operators are used to do most of the computation in a
1404program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1405produce a single value. The operands might represent
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1406multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1407The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1408necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1409<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1410</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1411<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1412<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1413Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1414<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1415<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1416<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1417</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1418<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1419<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1420<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1421<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1422 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1423 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1424Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1425<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1426<p>The value produced is the integer or floating point sum of the two
1427operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1428<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1429<pre> &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1430</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1431</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1432<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1433<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1434Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1435<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1436<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1437<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1438</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1439<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1440<p>The '<tt>sub</tt>' instruction returns the difference of its two
1441operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1442<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1443instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1444<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1445<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1446 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1447values.
1448This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1449Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1450<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1451<p>The value produced is the integer or floating point difference of
1452the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1453<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1454<pre> &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1455 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1456</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1457</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1458<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1459<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1460Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1461<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1462<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1463<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1464</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1465<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1466<p>The '<tt>mul</tt>' instruction returns the product of its two
1467operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1468<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1469<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1470 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1471values.
1472This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1473Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1474<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1475<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1476two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1477<p>There is no signed vs unsigned multiplication. The appropriate
1478action is taken based on the type of the operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1479<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1480<pre> &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1481</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1482</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1483<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1484<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1485Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1486<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1487<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1488<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1489</pre>
1490<h5>Overview:</h5>
1491<p>The '<tt>div</tt>' instruction returns the quotient of its two
1492operands.</p>
1493<h5>Arguments:</h5>
1494<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1495 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1496values.
1497This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1498Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1499<h5>Semantics:</h5>
1500<p>The value produced is the integer or floating point quotient of the
1501two operands.</p>
1502<h5>Example:</h5>
1503<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1504</pre>
1505</div>
1506<!-- _______________________________________________________________________ -->
1507<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1508Instruction</a> </div>
1509<div class="doc_text">
1510<h5>Syntax:</h5>
1511<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1512</pre>
1513<h5>Overview:</h5>
1514<p>The '<tt>rem</tt>' instruction returns the remainder from the
1515division of its two operands.</p>
1516<h5>Arguments:</h5>
1517<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1518 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1519values.
1520This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1521Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1522<h5>Semantics:</h5>
1523<p>This returns the <i>remainder</i> of a division (where the result
1524has the same sign as the divisor), not the <i>modulus</i> (where the
1525result has the same sign as the dividend) of a value. For more
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1526information about the difference, see <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1527 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1528Math Forum</a>.</p>
1529<h5>Example:</h5>
1530<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1531</pre>
1532</div>
1533<!-- _______________________________________________________________________ -->
1534<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1535Instructions</a> </div>
1536<div class="doc_text">
1537<h5>Syntax:</h5>
1538<pre> &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1539 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1540 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1541 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1542 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1543 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1544</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1545<h5>Overview:</h5>
1546<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1547value based on a comparison of their two operands.</p>
1548<h5>Arguments:</h5>
1549<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1550be of <a href="#t_firstclass">first class</a> type (it is not possible
1551to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1552or '<tt>void</tt>' values, etc...). Both arguments must have identical
1553types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1554<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1555<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1556value if both operands are equal.<br>
1557The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1558value if both operands are unequal.<br>
1559The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1560value if the first operand is less than the second operand.<br>
1561The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1562value if the first operand is greater than the second operand.<br>
1563The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1564value if the first operand is less than or equal to the second operand.<br>
1565The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1566value if the first operand is greater than or equal to the second
1567operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1568<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1569<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1570 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1571 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1572 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1573 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1574 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1575</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1576</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1577<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1578<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1579Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1580<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1581<p>Bitwise binary operators are used to do various forms of
1582bit-twiddling in a program. They are generally very efficient
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1583instructions and can commonly be strength reduced from other
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1584instructions. They require two operands, execute an operation on them,
1585and produce a single value. The resulting value of the bitwise binary
1586operators is always the same type as its first operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1587</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1588<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1589<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1590Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1591<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1592<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1593<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1594</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1595<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1596<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1597its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1598<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1599<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1600 href="#t_integral">integral</a> values. Both arguments must have
1601identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1602<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1603<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1604<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1605<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1606<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1607 <tbody>
1608 <tr>
1609 <td>In0</td>
1610 <td>In1</td>
1611 <td>Out</td>
1612 </tr>
1613 <tr>
1614 <td>0</td>
1615 <td>0</td>
1616 <td>0</td>
1617 </tr>
1618 <tr>
1619 <td>0</td>
1620 <td>1</td>
1621 <td>0</td>
1622 </tr>
1623 <tr>
1624 <td>1</td>
1625 <td>0</td>
1626 <td>0</td>
1627 </tr>
1628 <tr>
1629 <td>1</td>
1630 <td>1</td>
1631 <td>1</td>
1632 </tr>
1633 </tbody>
1634</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1635</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1636<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1637<pre> &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 &amp; %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1638 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1639 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1640</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1641</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1642<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1643<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1644<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1645<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1646<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1647</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1648<h5>Overview:</h5>
1649<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1650or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1651<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1652<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1653 href="#t_integral">integral</a> values. Both arguments must have
1654identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1655<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1656<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1657<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1658<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1659<table border="1" cellspacing="0" cellpadding="4">
1660 <tbody>
1661 <tr>
1662 <td>In0</td>
1663 <td>In1</td>
1664 <td>Out</td>
1665 </tr>
1666 <tr>
1667 <td>0</td>
1668 <td>0</td>
1669 <td>0</td>
1670 </tr>
1671 <tr>
1672 <td>0</td>
1673 <td>1</td>
1674 <td>1</td>
1675 </tr>
1676 <tr>
1677 <td>1</td>
1678 <td>0</td>
1679 <td>1</td>
1680 </tr>
1681 <tr>
1682 <td>1</td>
1683 <td>1</td>
1684 <td>1</td>
1685 </tr>
1686 </tbody>
1687</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1688</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1689<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1690<pre> &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1691 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1692 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1693</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1694</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1695<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1696<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1697Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1698<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1699<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1700<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1701</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1702<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1703<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1704or of its two operands. The <tt>xor</tt> is used to implement the
1705"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1706<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1707<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1708 href="#t_integral">integral</a> values. Both arguments must have
1709identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1710<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1711<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1712<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1713<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1714<table border="1" cellspacing="0" cellpadding="4">
1715 <tbody>
1716 <tr>
1717 <td>In0</td>
1718 <td>In1</td>
1719 <td>Out</td>
1720 </tr>
1721 <tr>
1722 <td>0</td>
1723 <td>0</td>
1724 <td>0</td>
1725 </tr>
1726 <tr>
1727 <td>0</td>
1728 <td>1</td>
1729 <td>1</td>
1730 </tr>
1731 <tr>
1732 <td>1</td>
1733 <td>0</td>
1734 <td>1</td>
1735 </tr>
1736 <tr>
1737 <td>1</td>
1738 <td>1</td>
1739 <td>0</td>
1740 </tr>
1741 </tbody>
1742</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1743</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1744<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1745<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1746<pre> &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1747 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1748 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1749 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1750</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1751</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1752<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1753<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1754Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1755<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1756<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1757<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1758</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1759<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1760<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1761the left a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1762<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1763<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1764 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1765type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1766<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1767<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1768<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1769<pre> &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 &lt;&lt; %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1770 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1771 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1772</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1773</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1774<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1775<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1776Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1777<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1778<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1779<pre> &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1780</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1781<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1782<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1783the right a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1784<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1785<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1786 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1787type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1788<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1789<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1790most significant bit is duplicated in the newly free'd bit positions.
1791If the first argument is unsigned, zero bits shall fill the empty
1792positions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1793<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1794<pre> &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 &gt;&gt; %var</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1795 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1796 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1797 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1798 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1799</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1800</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1801
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1802<!-- ======================================================================= -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1803<div class="doc_subsection">
1804 <a name="memoryops">Memory Access Operations</a>
1805</div>
1806
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1807<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1808
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1809<p>A key design point of an SSA-based representation is how it
1810represents memory. In LLVM, no memory locations are in SSA form, which
1811makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1812allocate, and free memory in LLVM.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1813
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1814</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1815
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1816<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1817<div class="doc_subsubsection">
1818 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
1819</div>
1820
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1821<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1822
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1823<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1824
1825<pre>
1826 &lt;result&gt; = malloc &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1827</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1828
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1829<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1830
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1831<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1832heap and returns a pointer to it.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1833
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1834<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1835
1836<p>The '<tt>malloc</tt>' instruction allocates
1837<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]1838bytes of memory from the operating system and returns a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1839appropriate type to the program. If "NumElements" is specified, it is the
1840number of elements allocated. If an alignment is specified, the value result
1841of the allocation is guaranteed to be aligned to at least that boundary. If
1842not specified, or if zero, the target can choose to align the allocation on any
1843convenient boundary.</p>
1844
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1845<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1846
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1847<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1848
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1849<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1850a pointer is returned.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1851
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1852<h5>Example:</h5>
1853
1854<pre>
1855 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
1856
1857 %size = <a href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1858 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1859 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1860 %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
1861 %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1862</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1863</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1864
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1865<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1866<div class="doc_subsubsection">
1867 <a name="i_free">'<tt>free</tt>' Instruction</a>
1868</div>
1869
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1870<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1871
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1872<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1873
1874<pre>
1875 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1876</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1877
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1878<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1879
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1880<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1881memory heap to be reallocated in the future.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1882
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1883<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1884
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1885<p>'<tt>value</tt>' shall be a pointer value that points to a value
1886that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1887instruction.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1888
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1889<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1890
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1891<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1892after this instruction executes.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1893
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1894<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1895
1896<pre>
1897 %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1898 free [4 x ubyte]* %array
1899</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1900</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1901
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1902<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1903<div class="doc_subsubsection">
1904 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
1905</div>
1906
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1907<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1908
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1909<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1910
1911<pre>
1912 &lt;result&gt; = alloca &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1913</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1914
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1915<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1916
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1917<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1918stack frame of the procedure that is live until the current function
1919returns to its caller.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1920
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1921<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1922
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1923<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1924bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1925appropriate type to the program. If "NumElements" is specified, it is the
1926number of elements allocated. If an alignment is specified, the value result
1927of the allocation is guaranteed to be aligned to at least that boundary. If
1928not specified, or if zero, the target can choose to align the allocation on any
1929convenient boundary.</p>
1930
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1931<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1932
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1933<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1934
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1935<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1936memory is automatically released when the function returns. The '<tt>alloca</tt>'
1937instruction is commonly used to represent automatic variables that must
1938have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]1939 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1940instructions), the memory is reclaimed.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1941
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1942<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1943
1944<pre>
1945 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1946 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1947 %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
1948 %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1949</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1950</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1951
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1952<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1953<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1954Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1955<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1956<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1957<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 Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1958<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1959<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1960<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1961<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1962address from which to load. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1963 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1964marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1965the number or order of execution of this <tt>load</tt> with other
1966volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1967instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1968<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1969<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1970<h5>Examples:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1971<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1972 <a
1973 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1974 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1975</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1976</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1977<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1978<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1979Instruction</a> </div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1980<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1981<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner12d456c2003-09-08 18:27:49 +0000[diff] [blame]1982 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1983</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1984<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1985<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1986<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1987<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1988to store and an address in which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1989operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1990operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1991optimizer is not allowed to modify the number or order of execution of
1992this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1993 href="#i_store">store</a></tt> instructions.</p>
1994<h5>Semantics:</h5>
1995<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1996at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1997<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1998<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1999 <a
2000 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2001 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
2002</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2003<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2004<div class="doc_subsubsection">
2005 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2006</div>
2007
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2008<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2009<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2010<pre>
2011 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2012</pre>
2013
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2014<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2015
2016<p>
2017The '<tt>getelementptr</tt>' instruction is used to get the address of a
2018subelement of an aggregate data structure.</p>
2019
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2020<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2021
2022<p>This instruction takes a list of integer constants that indicate what
2023elements of the aggregate object to index to. The actual types of the arguments
2024provided depend on the type of the first pointer argument. The
2025'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2026levels of a structure or to a specific index in an array. When indexing into a
2027structure, only <tt>uint</tt>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2028integer constants are allowed. When indexing into an array or pointer,
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2029<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
2030
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2031<p>For example, let's consider a C code fragment and how it gets
2032compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2033
2034<pre>
2035 struct RT {
2036 char A;
2037 int B[10][20];
2038 char C;
2039 };
2040 struct ST {
2041 int X;
2042 double Y;
2043 struct RT Z;
2044 };
2045
2046 int *foo(struct ST *s) {
2047 return &amp;s[1].Z.B[5][13];
2048 }
2049</pre>
2050
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2051<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2052
2053<pre>
2054 %RT = type { sbyte, [10 x [20 x int]], sbyte }
2055 %ST = type { int, double, %RT }
2056
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2057 implementation
2058
2059 int* %foo(%ST* %s) {
2060 entry:
2061 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2062 ret int* %reg
2063 }
2064</pre>
2065
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2066<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2067
2068<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2069on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2070and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
2071<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2072types require <tt>uint</tt> <b>constants</b>.</p>
2073
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2074<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2075type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
2076}</tt>' type, a structure. The second index indexes into the third element of
2077the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
2078sbyte }</tt>' type, another structure. The third index indexes into the second
2079element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
2080array. The two dimensions of the array are subscripted into, yielding an
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2081'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2082to this element, thus computing a value of '<tt>int*</tt>' type.</p>
2083
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2084<p>Note that it is perfectly legal to index partially through a
2085structure, returning a pointer to an inner element. Because of this,
2086the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2087
2088<pre>
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]2089 int* %foo(%ST* %s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2090 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
2091 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
2092 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
2093 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
2094 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
2095 ret int* %t5
2096 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2097</pre>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2098
2099<p>Note that it is undefined to access an array out of bounds: array and
2100pointer indexes must always be within the defined bounds of the array type.
2101The one exception for this rules is zero length arrays. These arrays are
2102defined to be accessible as variable length arrays, which requires access
2103beyond the zero'th element.</p>
2104
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2105<h5>Example:</h5>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2106
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2107<pre>
2108 <i>; yields [12 x ubyte]*:aptr</i>
2109 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
2110</pre>
2111
2112</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2113<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2114<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2115<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]2116<p>The instructions in this category are the "miscellaneous"
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2117instructions, which defy better classification.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2118</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2119<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2120<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2121Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2122<div class="doc_text">
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2123<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2124<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2125<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2126<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2127the SSA graph representing the function.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2128<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2129<p>The type of the incoming values are specified with the first type
2130field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2131as arguments, with one pair for each predecessor basic block of the
2132current block. Only values of <a href="#t_firstclass">first class</a>
2133type may be used as the value arguments to the PHI node. Only labels
2134may be used as the label arguments.</p>
2135<p>There must be no non-phi instructions between the start of a basic
2136block and the PHI instructions: i.e. PHI instructions must be first in
2137a basic block.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2138<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2139<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2140value specified by the parameter, depending on which basic block we
2141came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2142<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2143<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 Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2144</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2145
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2146<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2147<div class="doc_subsubsection">
2148 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2149</div>
2150
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2151<div class="doc_text">
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2152
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2153<h5>Syntax:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2154
2155<pre>
2156 &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2157</pre>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2158
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2159<h5>Overview:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2160
2161<p>
2162The '<tt>cast</tt>' instruction is used as the primitive means to convert
2163integers to floating point, change data type sizes, and break type safety (by
2164casting pointers).
2165</p>
2166
2167
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2168<h5>Arguments:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2169
2170<p>
2171The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2172class value, and a type to cast it to, which must also be a <a
2173href="#t_firstclass">first class</a> type.
2174</p>
2175
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2176<h5>Semantics:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2177
2178<p>
2179This instruction follows the C rules for explicit casts when determining how the
2180data being cast must change to fit in its new container.
2181</p>
2182
2183<p>
2184When casting to bool, any value that would be considered true in the context of
2185a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2186all else are '<tt>false</tt>'.
2187</p>
2188
2189<p>
2190When extending an integral value from a type of one signness to another (for
2191example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2192<b>source</b> value is signed, and zero-extended if the source value is
2193unsigned. <tt>bool</tt> values are always zero extended into either zero or
2194one.
2195</p>
2196
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2197<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2198
2199<pre>
2200 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattnerd8f8ede2002-06-25 18:03:17 +0000[diff] [blame]2201 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2202</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2203</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2204
2205<!-- _______________________________________________________________________ -->
2206<div class="doc_subsubsection">
2207 <a name="i_select">'<tt>select</tt>' Instruction</a>
2208</div>
2209
2210<div class="doc_text">
2211
2212<h5>Syntax:</h5>
2213
2214<pre>
2215 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2216</pre>
2217
2218<h5>Overview:</h5>
2219
2220<p>
2221The '<tt>select</tt>' instruction is used to choose one value based on a
2222condition, without branching.
2223</p>
2224
2225
2226<h5>Arguments:</h5>
2227
2228<p>
2229The '<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.
2230</p>
2231
2232<h5>Semantics:</h5>
2233
2234<p>
2235If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2236value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2237</p>
2238
2239<h5>Example:</h5>
2240
2241<pre>
2242 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2243</pre>
2244</div>
2245
2246
Robert Bocchinob5f210f2006-01-05 17:37:02 +0000[diff] [blame]2247<!-- _______________________________________________________________________ -->
2248<div class="doc_subsubsection">
2249 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2250</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2251
Robert Bocchinob5f210f2006-01-05 17:37:02 +0000[diff] [blame]2252<div class="doc_text">
2253
2254<h5>Syntax:</h5>
2255
2256<pre>
2257 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, uint &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2258</pre>
2259
2260<h5>Overview:</h5>
2261
2262<p>
2263The '<tt>extractelement</tt>' instruction extracts a single scalar
2264element from a vector at a specified index.
2265</p>
2266
2267
2268<h5>Arguments:</h5>
2269
2270<p>
2271The first operand of an '<tt>extractelement</tt>' instruction is a
2272value of <a href="#t_packed">packed</a> type. The second operand is
2273an index indicating the position from which to extract the element.
2274The index may be a variable.</p>
2275
2276<h5>Semantics:</h5>
2277
2278<p>
2279The result is a scalar of the same type as the element type of
2280<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2281<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2282results are undefined.
2283</p>
2284
2285<h5>Example:</h5>
2286
2287<pre>
2288 %result = extractelement &lt;4 x int&gt; %vec, uint 0 <i>; yields int</i>
2289</pre>
2290</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2291
2292
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2293<!-- _______________________________________________________________________ -->
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2294<div class="doc_subsubsection">
2295 <a name="i_call">'<tt>call</tt>' Instruction</a>
2296</div>
2297
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2298<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2299
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2300<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2301<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2302 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2303</pre>
2304
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2305<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2306
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2307<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2308
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2309<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2310
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2311<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2312
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2313<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2314 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2315 <p>The optional "tail" marker indicates whether the callee function accesses
2316 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2317 function call is eligible for tail call optimization. Note that calls may
2318 be marked "tail" even if they do not occur before a <a
2319 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2320 </li>
2321 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2322 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2323 convention</a> the call should use. If none is specified, the call defaults
2324 to using C calling conventions.
2325 </li>
2326 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2327 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2328 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2329 signature. This type can be omitted if the function is not varargs and
2330 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2331 </li>
2332 <li>
2333 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2334 be invoked. In most cases, this is a direct function invocation, but
2335 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2336 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2337 </li>
2338 <li>
2339 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]2340 function signature argument types. All arguments must be of
2341 <a href="#t_firstclass">first class</a> type. If the function signature
2342 indicates the function accepts a variable number of arguments, the extra
2343 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2344 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2345</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2346
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2347<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2348
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2349<p>The '<tt>call</tt>' instruction is used to cause control flow to
2350transfer to a specified function, with its incoming arguments bound to
2351the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2352instruction in the called function, control flow continues with the
2353instruction after the function call, and the return value of the
2354function is bound to the result argument. This is a simpler case of
2355the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2356
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2357<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2358
2359<pre>
2360 %retval = call int %test(int %argc)
2361 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2362 %X = tail call int %foo()
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2363 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2364</pre>
2365
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2366</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2367
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2368<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2369<div class="doc_subsubsection">
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]2370 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2371</div>
2372
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2373<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2374
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2375<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2376
2377<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2378 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2379</pre>
2380
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2381<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2382
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2383<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2384the "variable argument" area of a function call. It is used to implement the
2385<tt>va_arg</tt> macro in C.</p>
2386
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2387<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2388
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2389<p>This instruction takes a <tt>va_list*</tt> value and the type of
2390the argument. It returns a value of the specified argument type and
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]2391increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2392actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2393
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2394<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2395
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2396<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
2397type from the specified <tt>va_list</tt> and causes the
2398<tt>va_list</tt> to point to the next argument. For more information,
2399see the variable argument handling <a href="#int_varargs">Intrinsic
2400Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2401
2402<p>It is legal for this instruction to be called in a function which does not
2403take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2404function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2405
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2406<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2407href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2408argument.</p>
2409
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2410<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2411
2412<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2413
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2414</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2415
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2416<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2417<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2418<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2419
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2420<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2421
2422<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2423well known names and semantics and are required to follow certain
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2424restrictions. Overall, these instructions represent an extension mechanism for
2425the LLVM language that does not require changing all of the transformations in
2426LLVM to add to the language (or the bytecode reader/writer, the parser,
2427etc...).</p>
2428
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2429<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
2430prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2431this. Intrinsic functions must always be external functions: you cannot define
2432the body of intrinsic functions. Intrinsic functions may only be used in call
2433or invoke instructions: it is illegal to take the address of an intrinsic
2434function. Additionally, because intrinsic functions are part of the LLVM
2435language, it is required that they all be documented here if any are added.</p>
2436
2437
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2438<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner90391c12005-05-11 03:35:57 +0000[diff] [blame]2439href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2440</p>
2441
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2442</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2443
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2444<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2445<div class="doc_subsection">
2446 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2447</div>
2448
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2449<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2450
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2451<p>Variable argument support is defined in LLVM with the <a
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]2452 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2453intrinsic functions. These functions are related to the similarly
2454named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2455
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2456<p>All of these functions operate on arguments that use a
2457target-specific value type "<tt>va_list</tt>". The LLVM assembly
2458language reference manual does not define what this type is, so all
2459transformations should be prepared to handle intrinsics with any type
2460used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2461
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2462<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2463instruction and the variable argument handling intrinsic functions are
2464used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2465
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2466<pre>
2467int %test(int %X, ...) {
2468 ; Initialize variable argument processing
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2469 %ap = alloca sbyte*
2470 call void %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2471
2472 ; Read a single integer argument
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2473 %tmp = va_arg sbyte** %ap, int
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2474
2475 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2476 %aq = alloca sbyte*
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]2477 call void %<a href="#i_va_copy">llvm.va_copy</a>(sbyte** %aq, sbyte** %ap)
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2478 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2479
2480 ; Stop processing of arguments.
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2481 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2482 ret int %tmp
2483}
2484</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2485</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2486
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2487<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2488<div class="doc_subsubsection">
2489 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2490</div>
2491
2492
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2493<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2494<h5>Syntax:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2495<pre> declare void %llvm.va_start(&lt;va_list&gt;* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2496<h5>Overview:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2497<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
2498<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
2499href="#i_va_arg">va_arg</a></tt>.</p>
2500
2501<h5>Arguments:</h5>
2502
2503<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
2504
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2505<h5>Semantics:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2506
2507<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
2508macro available in C. In a target-dependent way, it initializes the
2509<tt>va_list</tt> element the argument points to, so that the next call to
2510<tt>va_arg</tt> will produce the first variable argument passed to the function.
2511Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2512last argument of the function, the compiler can figure that out.</p>
2513
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2514</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2515
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2516<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2517<div class="doc_subsubsection">
2518 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2519</div>
2520
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2521<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2522<h5>Syntax:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2523<pre> declare void %llvm.va_end(&lt;va_list*&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2524<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2525<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2526which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2527or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2528<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2529<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2530<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2531<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2532macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2533Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2534 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2535with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2536</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2537
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2538<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2539<div class="doc_subsubsection">
2540 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2541</div>
2542
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2543<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2544
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2545<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2546
2547<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2548 declare void %llvm.va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]2549 &lt;va_list&gt;* &lt;srcarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2550</pre>
2551
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2552<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2553
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2554<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
2555the source argument list to the destination argument list.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2556
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2557<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2558
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2559<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]2560The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2561
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2562
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2563<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2564
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2565<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
2566available in C. In a target-dependent way, it copies the source
2567<tt>va_list</tt> element into the destination list. This intrinsic is necessary
2568because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2569arbitrarily complex and require memory allocation, for example.</p>
2570
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2571</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2572
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2573<!-- ======================================================================= -->
2574<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2575 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2576</div>
2577
2578<div class="doc_text">
2579
2580<p>
2581LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2582Collection</a> requires the implementation and generation of these intrinsics.
2583These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2584stack</a>, as well as garbage collector implementations that require <a
2585href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2586Front-ends for type-safe garbage collected languages should generate these
2587intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2588href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2589</p>
2590</div>
2591
2592<!-- _______________________________________________________________________ -->
2593<div class="doc_subsubsection">
2594 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2595</div>
2596
2597<div class="doc_text">
2598
2599<h5>Syntax:</h5>
2600
2601<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2602 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2603</pre>
2604
2605<h5>Overview:</h5>
2606
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2607<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2608the code generator, and allows some metadata to be associated with it.</p>
2609
2610<h5>Arguments:</h5>
2611
2612<p>The first argument specifies the address of a stack object that contains the
2613root pointer. The second pointer (which must be either a constant or a global
2614value address) contains the meta-data to be associated with the root.</p>
2615
2616<h5>Semantics:</h5>
2617
2618<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2619location. At compile-time, the code generator generates information to allow
2620the runtime to find the pointer at GC safe points.
2621</p>
2622
2623</div>
2624
2625
2626<!-- _______________________________________________________________________ -->
2627<div class="doc_subsubsection">
2628 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2629</div>
2630
2631<div class="doc_text">
2632
2633<h5>Syntax:</h5>
2634
2635<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2636 declare sbyte* %llvm.gcread(sbyte** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2637</pre>
2638
2639<h5>Overview:</h5>
2640
2641<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2642locations, allowing garbage collector implementations that require read
2643barriers.</p>
2644
2645<h5>Arguments:</h5>
2646
2647<p>The argument is the address to read from, which should be an address
2648allocated from the garbage collector.</p>
2649
2650<h5>Semantics:</h5>
2651
2652<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2653instruction, but may be replaced with substantially more complex code by the
2654garbage collector runtime, as needed.</p>
2655
2656</div>
2657
2658
2659<!-- _______________________________________________________________________ -->
2660<div class="doc_subsubsection">
2661 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2662</div>
2663
2664<div class="doc_text">
2665
2666<h5>Syntax:</h5>
2667
2668<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2669 declare void %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2670</pre>
2671
2672<h5>Overview:</h5>
2673
2674<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2675locations, allowing garbage collector implementations that require write
2676barriers (such as generational or reference counting collectors).</p>
2677
2678<h5>Arguments:</h5>
2679
2680<p>The first argument is the reference to store, and the second is the heap
2681location to store to.</p>
2682
2683<h5>Semantics:</h5>
2684
2685<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2686instruction, but may be replaced with substantially more complex code by the
2687garbage collector runtime, as needed.</p>
2688
2689</div>
2690
2691
2692
2693<!-- ======================================================================= -->
2694<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2695 <a name="int_codegen">Code Generator Intrinsics</a>
2696</div>
2697
2698<div class="doc_text">
2699<p>
2700These intrinsics are provided by LLVM to expose special features that may only
2701be implemented with code generator support.
2702</p>
2703
2704</div>
2705
2706<!-- _______________________________________________________________________ -->
2707<div class="doc_subsubsection">
2708 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2709</div>
2710
2711<div class="doc_text">
2712
2713<h5>Syntax:</h5>
2714<pre>
Chris Lattnerb3d430e2006-01-13 01:20:27 +0000[diff] [blame]2715 declare sbyte *%llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2716</pre>
2717
2718<h5>Overview:</h5>
2719
2720<p>
2721The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2722indicating the return address of the current function or one of its callers.
2723</p>
2724
2725<h5>Arguments:</h5>
2726
2727<p>
2728The argument to this intrinsic indicates which function to return the address
2729for. Zero indicates the calling function, one indicates its caller, etc. The
2730argument is <b>required</b> to be a constant integer value.
2731</p>
2732
2733<h5>Semantics:</h5>
2734
2735<p>
2736The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2737the return address of the specified call frame, or zero if it cannot be
2738identified. The value returned by this intrinsic is likely to be incorrect or 0
2739for arguments other than zero, so it should only be used for debugging purposes.
2740</p>
2741
2742<p>
2743Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]2744aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2745source-language caller.
2746</p>
2747</div>
2748
2749
2750<!-- _______________________________________________________________________ -->
2751<div class="doc_subsubsection">
2752 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2753</div>
2754
2755<div class="doc_text">
2756
2757<h5>Syntax:</h5>
2758<pre>
Chris Lattnerb3d430e2006-01-13 01:20:27 +0000[diff] [blame]2759 declare sbyte *%llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2760</pre>
2761
2762<h5>Overview:</h5>
2763
2764<p>
2765The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2766pointer value for the specified stack frame.
2767</p>
2768
2769<h5>Arguments:</h5>
2770
2771<p>
2772The argument to this intrinsic indicates which function to return the frame
2773pointer for. Zero indicates the calling function, one indicates its caller,
2774etc. The argument is <b>required</b> to be a constant integer value.
2775</p>
2776
2777<h5>Semantics:</h5>
2778
2779<p>
2780The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2781the frame address of the specified call frame, or zero if it cannot be
2782identified. The value returned by this intrinsic is likely to be incorrect or 0
2783for arguments other than zero, so it should only be used for debugging purposes.
2784</p>
2785
2786<p>
2787Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]2788aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2789source-language caller.
2790</p>
2791</div>
2792
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2793<!-- _______________________________________________________________________ -->
2794<div class="doc_subsubsection">
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]2795 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
2796</div>
2797
2798<div class="doc_text">
2799
2800<h5>Syntax:</h5>
2801<pre>
2802 declare sbyte *%llvm.stacksave()
2803</pre>
2804
2805<h5>Overview:</h5>
2806
2807<p>
2808The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
2809the function stack, for use with <a href="#i_stackrestore">
2810<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
2811features like scoped automatic variable sized arrays in C99.
2812</p>
2813
2814<h5>Semantics:</h5>
2815
2816<p>
2817This intrinsic returns a opaque pointer value that can be passed to <a
2818href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
2819<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
2820<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
2821state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
2822practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
2823that were allocated after the <tt>llvm.stacksave</tt> was executed.
2824</p>
2825
2826</div>
2827
2828<!-- _______________________________________________________________________ -->
2829<div class="doc_subsubsection">
2830 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
2831</div>
2832
2833<div class="doc_text">
2834
2835<h5>Syntax:</h5>
2836<pre>
2837 declare void %llvm.stackrestore(sbyte* %ptr)
2838</pre>
2839
2840<h5>Overview:</h5>
2841
2842<p>
2843The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
2844the function stack to the state it was in when the corresponding <a
2845href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
2846useful for implementing language features like scoped automatic variable sized
2847arrays in C99.
2848</p>
2849
2850<h5>Semantics:</h5>
2851
2852<p>
2853See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
2854</p>
2855
2856</div>
2857
2858
2859<!-- _______________________________________________________________________ -->
2860<div class="doc_subsubsection">
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2861 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
2862</div>
2863
2864<div class="doc_text">
2865
2866<h5>Syntax:</h5>
2867<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2868 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
2869 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2870</pre>
2871
2872<h5>Overview:</h5>
2873
2874
2875<p>
2876The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2877a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
2878no
2879effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]2880characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2881</p>
2882
2883<h5>Arguments:</h5>
2884
2885<p>
2886<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
2887determining if the fetch should be for a read (0) or write (1), and
2888<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]2889locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2890<tt>locality</tt> arguments must be constant integers.
2891</p>
2892
2893<h5>Semantics:</h5>
2894
2895<p>
2896This intrinsic does not modify the behavior of the program. In particular,
2897prefetches cannot trap and do not produce a value. On targets that support this
2898intrinsic, the prefetch can provide hints to the processor cache for better
2899performance.
2900</p>
2901
2902</div>
2903
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2904<!-- _______________________________________________________________________ -->
2905<div class="doc_subsubsection">
2906 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
2907</div>
2908
2909<div class="doc_text">
2910
2911<h5>Syntax:</h5>
2912<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2913 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2914</pre>
2915
2916<h5>Overview:</h5>
2917
2918
2919<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2920The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
2921(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2922code to simulators and other tools. The method is target specific, but it is
2923expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]2924The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnere64d41d2005-11-15 06:07:55 +0000[diff] [blame]2925after optimizations. It is possible that the presence of a marker will inhibit
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2926optimizations. The intended use is to be inserted after optmizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2927correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2928</p>
2929
2930<h5>Arguments:</h5>
2931
2932<p>
2933<tt>id</tt> is a numerical id identifying the marker.
2934</p>
2935
2936<h5>Semantics:</h5>
2937
2938<p>
2939This intrinsic does not modify the behavior of the program. Backends that do not
2940support this intrinisic may ignore it.
2941</p>
2942
2943</div>
2944
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]2945<!-- _______________________________________________________________________ -->
2946<div class="doc_subsubsection">
2947 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
2948</div>
2949
2950<div class="doc_text">
2951
2952<h5>Syntax:</h5>
2953<pre>
2954 declare ulong %llvm.readcyclecounter( )
2955</pre>
2956
2957<h5>Overview:</h5>
2958
2959
2960<p>
2961The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
2962counter register (or similar low latency, high accuracy clocks) on those targets
2963that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
2964As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
2965should only be used for small timings.
2966</p>
2967
2968<h5>Semantics:</h5>
2969
2970<p>
2971When directly supported, reading the cycle counter should not modify any memory.
2972Implementations are allowed to either return a application specific value or a
2973system wide value. On backends without support, this is lowered to a constant 0.
2974</p>
2975
2976</div>
2977
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2978
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2979<!-- ======================================================================= -->
2980<div class="doc_subsection">
2981 <a name="int_os">Operating System Intrinsics</a>
2982</div>
2983
2984<div class="doc_text">
2985<p>
2986These intrinsics are provided by LLVM to support the implementation of
2987operating system level code.
2988</p>
2989
2990</div>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2991
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2992<!-- _______________________________________________________________________ -->
2993<div class="doc_subsubsection">
2994 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2995</div>
2996
2997<div class="doc_text">
2998
2999<h5>Syntax:</h5>
3000<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3001 declare &lt;integer type&gt; %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3002</pre>
3003
3004<h5>Overview:</h5>
3005
3006<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]3007The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
3008I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3009</p>
3010
3011<h5>Arguments:</h5>
3012
3013<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]3014The argument to this intrinsic indicates the hardware I/O address from which
3015to read the data. The address is in the hardware I/O address namespace (as
3016opposed to being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3017</p>
3018
3019<h5>Semantics:</h5>
3020
3021<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]3022The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
3023specified by <i>address</i> and returns the value. The address and return
3024value must be integers, but the size is dependent upon the platform upon which
3025the program is code generated. For example, on x86, the address must be an
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]3026unsigned 16-bit value, and the return value must be 8, 16, or 32 bits.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3027</p>
3028
3029</div>
3030
3031<!-- _______________________________________________________________________ -->
3032<div class="doc_subsubsection">
3033 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
3034</div>
3035
3036<div class="doc_text">
3037
3038<h5>Syntax:</h5>
3039<pre>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]3040 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
3041 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
3042 &lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3043</pre>
3044
3045<h5>Overview:</h5>
3046
3047<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]3048The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
3049I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3050</p>
3051
3052<h5>Arguments:</h5>
3053
3054<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3055The first argument is the value to write to the I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3056</p>
3057
3058<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3059The second argument indicates the hardware I/O address to which data should be
3060written. The address is in the hardware I/O address namespace (as opposed to
3061being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3062</p>
3063
3064<h5>Semantics:</h5>
3065
3066<p>
3067The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
3068specified by <i>address</i>. The address and value must be integers, but the
3069size is dependent upon the platform upon which the program is code generated.
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]3070For example, on x86, the address must be an unsigned 16-bit value, and the
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]3071value written must be 8, 16, or 32 bits in length.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]3072</p>
3073
3074</div>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3075
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3076<!-- _______________________________________________________________________ -->
3077<div class="doc_subsubsection">
3078 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
3079</div>
3080
3081<div class="doc_text">
3082
3083<h5>Syntax:</h5>
3084<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3085 declare &lt;result&gt; %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3086</pre>
3087
3088<h5>Overview:</h5>
3089
3090<p>
3091The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
3092address.
3093</p>
3094
3095<h5>Arguments:</h5>
3096
3097<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3098The argument to this intrinsic is a pointer indicating the memory address from
3099which to read the data. The data must be a
3100<a href="#t_firstclass">first class</a> type.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3101</p>
3102
3103<h5>Semantics:</h5>
3104
3105<p>
3106The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3107location specified by <i>pointer</i> and returns the value. The argument must
3108be a pointer, and the return value must be a
3109<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]3110may not support I/O on all first class types. For example, 32-bit processors
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3111may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3112</p>
3113
3114<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3115This intrinsic enforces an in-order memory model for llvm.readio and
3116llvm.writeio calls on machines that use dynamic scheduling. Dynamically
3117scheduled processors may execute loads and stores out of order, re-ordering at
3118run time accesses to memory mapped I/O registers. Using these intrinsics
3119ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3120</p>
3121
3122</div>
3123
3124<!-- _______________________________________________________________________ -->
3125<div class="doc_subsubsection">
3126 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
3127</div>
3128
3129<div class="doc_text">
3130
3131<h5>Syntax:</h5>
3132<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3133 declare void %llvm.writeio (&lt;ty1&gt; &lt;value&gt;, &lt;ty2&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3134</pre>
3135
3136<h5>Overview:</h5>
3137
3138<p>
3139The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
3140mapped I/O address.
3141</p>
3142
3143<h5>Arguments:</h5>
3144
3145<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3146The first argument is the value to write to the memory mapped I/O location.
3147The second argument is a pointer indicating the memory address to which the
3148data should be written.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3149</p>
3150
3151<h5>Semantics:</h5>
3152
3153<p>
3154The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3155I/O address specified by <i>pointer</i>. The value must be a
3156<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]3157may not support I/O on all first class types. For example, 32-bit processors
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3158may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3159</p>
3160
3161<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]3162This intrinsic enforces an in-order memory model for llvm.readio and
3163llvm.writeio calls on machines that use dynamic scheduling. Dynamically
3164scheduled processors may execute loads and stores out of order, re-ordering at
3165run time accesses to memory mapped I/O registers. Using these intrinsics
3166ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]3167</p>
3168
3169</div>
3170
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3171<!-- ======================================================================= -->
3172<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3173 <a name="int_libc">Standard C Library Intrinsics</a>
3174</div>
3175
3176<div class="doc_text">
3177<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3178LLVM provides intrinsics for a few important standard C library functions.
3179These intrinsics allow source-language front-ends to pass information about the
3180alignment of the pointer arguments to the code generator, providing opportunity
3181for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3182</p>
3183
3184</div>
3185
3186<!-- _______________________________________________________________________ -->
3187<div class="doc_subsubsection">
3188 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
3189</div>
3190
3191<div class="doc_text">
3192
3193<h5>Syntax:</h5>
3194<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3195 declare void %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3196 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3197</pre>
3198
3199<h5>Overview:</h5>
3200
3201<p>
3202The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3203location to the destination location.
3204</p>
3205
3206<p>
3207Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
3208does not return a value, and takes an extra alignment argument.
3209</p>
3210
3211<h5>Arguments:</h5>
3212
3213<p>
3214The first argument is a pointer to the destination, the second is a pointer to
3215the source. The third argument is an (arbitrarily sized) integer argument
3216specifying the number of bytes to copy, and the fourth argument is the alignment
3217of the source and destination locations.
3218</p>
3219
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3220<p>
3221If the call to this intrinisic has an alignment value that is not 0 or 1, then
3222the caller guarantees that the size of the copy is a multiple of the alignment
3223and that both the source and destination pointers are aligned to that boundary.
3224</p>
3225
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3226<h5>Semantics:</h5>
3227
3228<p>
3229The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3230location to the destination location, which are not allowed to overlap. It
3231copies "len" bytes of memory over. If the argument is known to be aligned to
3232some boundary, this can be specified as the fourth argument, otherwise it should
3233be set to 0 or 1.
3234</p>
3235</div>
3236
3237
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3238<!-- _______________________________________________________________________ -->
3239<div class="doc_subsubsection">
3240 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3241</div>
3242
3243<div class="doc_text">
3244
3245<h5>Syntax:</h5>
3246<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3247 declare void %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3248 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3249</pre>
3250
3251<h5>Overview:</h5>
3252
3253<p>
3254The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
3255location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
3256intrinsic but allows the two memory locations to overlap.
3257</p>
3258
3259<p>
3260Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
3261does not return a value, and takes an extra alignment argument.
3262</p>
3263
3264<h5>Arguments:</h5>
3265
3266<p>
3267The first argument is a pointer to the destination, the second is a pointer to
3268the source. The third argument is an (arbitrarily sized) integer argument
3269specifying the number of bytes to copy, and the fourth argument is the alignment
3270of the source and destination locations.
3271</p>
3272
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3273<p>
3274If the call to this intrinisic has an alignment value that is not 0 or 1, then
3275the caller guarantees that the size of the copy is a multiple of the alignment
3276and that both the source and destination pointers are aligned to that boundary.
3277</p>
3278
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3279<h5>Semantics:</h5>
3280
3281<p>
3282The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
3283location to the destination location, which may overlap. It
3284copies "len" bytes of memory over. If the argument is known to be aligned to
3285some boundary, this can be specified as the fourth argument, otherwise it should
3286be set to 0 or 1.
3287</p>
3288</div>
3289
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3290
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3291<!-- _______________________________________________________________________ -->
3292<div class="doc_subsubsection">
3293 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
3294</div>
3295
3296<div class="doc_text">
3297
3298<h5>Syntax:</h5>
3299<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3300 declare void %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3301 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3302</pre>
3303
3304<h5>Overview:</h5>
3305
3306<p>
3307The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
3308byte value.
3309</p>
3310
3311<p>
3312Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3313does not return a value, and takes an extra alignment argument.
3314</p>
3315
3316<h5>Arguments:</h5>
3317
3318<p>
3319The first argument is a pointer to the destination to fill, the second is the
3320byte value to fill it with, the third argument is an (arbitrarily sized) integer
3321argument specifying the number of bytes to fill, and the fourth argument is the
3322known alignment of destination location.
3323</p>
3324
3325<p>
3326If the call to this intrinisic has an alignment value that is not 0 or 1, then
3327the caller guarantees that the size of the copy is a multiple of the alignment
3328and that the destination pointer is aligned to that boundary.
3329</p>
3330
3331<h5>Semantics:</h5>
3332
3333<p>
3334The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
3335destination location. If the argument is known to be aligned to some boundary,
3336this can be specified as the fourth argument, otherwise it should be set to 0 or
33371.
3338</p>
3339</div>
3340
3341
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3342<!-- _______________________________________________________________________ -->
3343<div class="doc_subsubsection">
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3344 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
3345</div>
3346
3347<div class="doc_text">
3348
3349<h5>Syntax:</h5>
3350<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3351 declare bool %llvm.isunordered(&lt;float or double&gt; Val1, &lt;float or double&gt; Val2)
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3352</pre>
3353
3354<h5>Overview:</h5>
3355
3356<p>
3357The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
3358specified floating point values is a NAN.
3359</p>
3360
3361<h5>Arguments:</h5>
3362
3363<p>
3364The arguments are floating point numbers of the same type.
3365</p>
3366
3367<h5>Semantics:</h5>
3368
3369<p>
3370If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3371false.
3372</p>
3373</div>
3374
3375
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]3376<!-- _______________________________________________________________________ -->
3377<div class="doc_subsubsection">
3378 <a name="i_sqrt">'<tt>llvm.sqrt</tt>' Intrinsic</a>
3379</div>
3380
3381<div class="doc_text">
3382
3383<h5>Syntax:</h5>
3384<pre>
3385 declare &lt;float or double&gt; %llvm.sqrt(&lt;float or double&gt; Val)
3386</pre>
3387
3388<h5>Overview:</h5>
3389
3390<p>
3391The '<tt>llvm.sqrt</tt>' intrinsic returns the sqrt of the specified operand,
3392returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
3393<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
3394negative numbers (which allows for better optimization).
3395</p>
3396
3397<h5>Arguments:</h5>
3398
3399<p>
3400The argument and return value are floating point numbers of the same type.
3401</p>
3402
3403<h5>Semantics:</h5>
3404
3405<p>
3406This function returns the sqrt of the specified operand if it is a positive
3407floating point number.
3408</p>
3409</div>
3410
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3411<!-- ======================================================================= -->
3412<div class="doc_subsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3413 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3414</div>
3415
3416<div class="doc_text">
3417<p>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3418LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3419These allow efficient code generation for some algorithms.
3420</p>
3421
3422</div>
3423
3424<!-- _______________________________________________________________________ -->
3425<div class="doc_subsubsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3426 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
3427</div>
3428
3429<div class="doc_text">
3430
3431<h5>Syntax:</h5>
3432<pre>
3433 declare ushort %llvm.bswap.i16( ushort &lt;id&gt; )
3434 declare uint %llvm.bswap.i32( uint &lt;id&gt; )
3435 declare ulong %llvm.bswap.i64( ulong &lt;id&gt; )
3436</pre>
3437
3438<h5>Overview:</h5>
3439
3440<p>
3441The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
344264 bit quantity. These are useful for performing operations on data that is not
3443in the target's native byte order.
3444</p>
3445
3446<h5>Semantics:</h5>
3447
3448<p>
3449The llvm.bswap.16 intrinsic returns a ushort value that has the high and low
3450byte of the input ushort swapped. Similarly, the llvm.bswap.i32 intrinsic
3451returns a uint value that has the four bytes of the input uint swapped, so that
3452if the input bytes are numbered 0, 1, 2, 3 then the returned uint will have its
3453bytes in 3, 2, 1, 0 order. The llvm.bswap.i64 intrinsic extends this concept
3454to 64 bits.
3455</p>
3456
3457</div>
3458
3459<!-- _______________________________________________________________________ -->
3460<div class="doc_subsubsection">
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3461 <a name="int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic</a>
3462</div>
3463
3464<div class="doc_text">
3465
3466<h5>Syntax:</h5>
3467<pre>
3468 declare int %llvm.ctpop(int &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3469</pre>
3470
3471<h5>Overview:</h5>
3472
3473<p>
3474The '<tt>llvm.ctpop</tt>' intrinsic counts the number of ones in a variable.
3475</p>
3476
3477<h5>Arguments:</h5>
3478
3479<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3480The only argument is the value to be counted. The argument may be of any
3481integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3482</p>
3483
3484<h5>Semantics:</h5>
3485
3486<p>
3487The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3488</p>
3489</div>
3490
3491<!-- _______________________________________________________________________ -->
3492<div class="doc_subsubsection">
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3493 <a name="int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic</a>
3494</div>
3495
3496<div class="doc_text">
3497
3498<h5>Syntax:</h5>
3499<pre>
3500 declare int %llvm.ctlz(int &lt;src&gt;)
3501
3502</pre>
3503
3504<h5>Overview:</h5>
3505
3506<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3507The '<tt>llvm.ctlz</tt>' intrinsic counts the number of leading zeros in a
3508variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3509</p>
3510
3511<h5>Arguments:</h5>
3512
3513<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3514The only argument is the value to be counted. The argument may be of any
3515integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3516</p>
3517
3518<h5>Semantics:</h5>
3519
3520<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3521The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
3522in a variable. If the src == 0 then the result is the size in bits of the type
3523of src. For example, <tt>llvm.cttz(int 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3524</p>
3525</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3526
3527
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3528
3529<!-- _______________________________________________________________________ -->
3530<div class="doc_subsubsection">
3531 <a name="int_cttz">'<tt>llvm.cttz</tt>' Intrinsic</a>
3532</div>
3533
3534<div class="doc_text">
3535
3536<h5>Syntax:</h5>
3537<pre>
3538 declare int %llvm.cttz(int &lt;src&gt;)
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3539</pre>
3540
3541<h5>Overview:</h5>
3542
3543<p>
3544The '<tt>llvm.cttz</tt>' intrinsic counts the number of trailing zeros.
3545</p>
3546
3547<h5>Arguments:</h5>
3548
3549<p>
3550The only argument is the value to be counted. The argument may be of any
3551integer type. The return type must match the argument type.
3552</p>
3553
3554<h5>Semantics:</h5>
3555
3556<p>
3557The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
3558in a variable. If the src == 0 then the result is the size in bits of the type
3559of src. For example, <tt>llvm.cttz(2) = 1</tt>.
3560</p>
3561</div>
3562
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3563<!-- ======================================================================= -->
3564<div class="doc_subsection">
3565 <a name="int_debugger">Debugger Intrinsics</a>
3566</div>
3567
3568<div class="doc_text">
3569<p>
3570The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3571are described in the <a
3572href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3573Debugging</a> document.
3574</p>
3575</div>
3576
3577
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3578<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3579<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]3580<address>
3581 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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3585
3586 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
3587 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
3588 Last modified: $Date$
3589</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3590</body>
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