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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 0ae4a3357a556261f25b1584a2d9914637c69e65 / . / docs / LangRef.html
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4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
Reid Spencer3921c742004-08-26 20:44:00 +0000[diff] [blame]6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]25 <li><a href="#globalvars">Global Variables</a></li>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]26 <li><a href="#functionstructure">Functions</a></li>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]27 <li><a href="#paramattrs">Parameter Attributes</a></li>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]28 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
Reid Spencerde151942007-02-19 23:54:10 +0000[diff] [blame]29 <li><a href="#datalayout">Data Layout</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]30 </ol>
31 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]32 <li><a href="#typesystem">Type System</a>
33 <ol>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]34 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]35 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]36 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]37 </ol>
38 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]39 <li><a href="#t_derived">Derived Types</a>
40 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]41 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]42 <li><a href="#t_function">Function Type</a></li>
43 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]44 <li><a href="#t_struct">Structure Type</a></li>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]45 <li><a href="#t_pstruct">Packed Structure Type</a></li>
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]46 <li><a href="#t_vector">Vector Type</a></li>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]47 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]48 </ol>
49 </li>
50 </ol>
51 </li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]52 <li><a href="#constants">Constants</a>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]53 <ol>
54 <li><a href="#simpleconstants">Simple Constants</a>
55 <li><a href="#aggregateconstants">Aggregate Constants</a>
56 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
57 <li><a href="#undefvalues">Undefined Values</a>
58 <li><a href="#constantexprs">Constant Expressions</a>
59 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]60 </li>
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]61 <li><a href="#othervalues">Other Values</a>
62 <ol>
63 <li><a href="#inlineasm">Inline Assembler Expressions</a>
64 </ol>
65 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]66 <li><a href="#instref">Instruction Reference</a>
67 <ol>
68 <li><a href="#terminators">Terminator Instructions</a>
69 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]70 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
71 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]72 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
73 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]74 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]75 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]76 </ol>
77 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]78 <li><a href="#binaryops">Binary Operations</a>
79 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]80 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
81 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
82 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]83 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
84 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
85 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]86 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
87 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
88 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]89 </ol>
90 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]91 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
92 <ol>
Reid Spencer8e11bf82007-02-02 13:57:07 +0000[diff] [blame]93 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
94 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
95 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]96 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]97 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]98 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]99 </ol>
100 </li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]101 <li><a href="#vectorops">Vector Operations</a>
102 <ol>
103 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
104 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
105 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]106 </ol>
107 </li>
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]108 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]109 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]110 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
111 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
112 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]113 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
114 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
115 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]116 </ol>
117 </li>
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]118 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]119 <ol>
120 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
121 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
122 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
123 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
124 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]125 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
126 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
127 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
128 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]129 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
130 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]131 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]132 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]133 <li><a href="#otherops">Other Operations</a>
134 <ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]135 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
136 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]137 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]138 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]139 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]140 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]141 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]142 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]143 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]144 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]145 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]146 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]147 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
148 <ol>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]149 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
150 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
151 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]152 </ol>
153 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]154 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
155 <ol>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]156 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
157 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
158 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]159 </ol>
160 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]161 <li><a href="#int_codegen">Code Generator Intrinsics</a>
162 <ol>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]163 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
164 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
165 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
166 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
167 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
168 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
169 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]170 </ol>
171 </li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]172 <li><a href="#int_libc">Standard C Library Intrinsics</a>
173 <ol>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]174 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
175 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
176 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
177 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
178 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]179 </ol>
180 </li>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]181 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]182 <ol>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]183 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]184 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
185 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
186 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Reid Spencerf86037f2007-04-11 23:23:49 +0000[diff] [blame]187 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
188 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]189 </ol>
190 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]191 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Jim Laskeydd4ef1b2007-03-14 19:31:19 +0000[diff] [blame]192 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]193 </ol>
194 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]195</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]196
197<div class="doc_author">
198 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
199 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]200</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]201
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]202<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]203<div class="doc_section"> <a name="abstract">Abstract </a></div>
204<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]205
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]206<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]207<p>This document is a reference manual for the LLVM assembly language.
208LLVM is an SSA based representation that provides type safety,
209low-level operations, flexibility, and the capability of representing
210'all' high-level languages cleanly. It is the common code
211representation used throughout all phases of the LLVM compilation
212strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]213</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]214
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]215<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]216<div class="doc_section"> <a name="introduction">Introduction</a> </div>
217<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]218
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]219<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]220
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]221<p>The LLVM code representation is designed to be used in three
222different forms: as an in-memory compiler IR, as an on-disk bytecode
223representation (suitable for fast loading by a Just-In-Time compiler),
224and as a human readable assembly language representation. This allows
225LLVM to provide a powerful intermediate representation for efficient
226compiler transformations and analysis, while providing a natural means
227to debug and visualize the transformations. The three different forms
228of LLVM are all equivalent. This document describes the human readable
229representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]230
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]231<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]232while being expressive, typed, and extensible at the same time. It
233aims to be a "universal IR" of sorts, by being at a low enough level
234that high-level ideas may be cleanly mapped to it (similar to how
235microprocessors are "universal IR's", allowing many source languages to
236be mapped to them). By providing type information, LLVM can be used as
237the target of optimizations: for example, through pointer analysis, it
238can be proven that a C automatic variable is never accessed outside of
239the current function... allowing it to be promoted to a simple SSA
240value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]241
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]242</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]243
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]244<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]245<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]246
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]247<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]248
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]249<p>It is important to note that this document describes 'well formed'
250LLVM assembly language. There is a difference between what the parser
251accepts and what is considered 'well formed'. For example, the
252following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]253
254<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]255 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]256</pre>
257
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]258<p>...because the definition of <tt>%x</tt> does not dominate all of
259its uses. The LLVM infrastructure provides a verification pass that may
260be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]261automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]262the optimizer before it outputs bytecode. The violations pointed out
263by the verifier pass indicate bugs in transformation passes or input to
264the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]265
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]266<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]267
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]268<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]269<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]270<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]271
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]272<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]273
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]274<p>LLVM uses three different forms of identifiers, for different
275purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]276
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]277<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]278 <li>Named values are represented as a string of characters with a '%' prefix.
279 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
280 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
281 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]282 with quotes. In this way, anything except a <tt>&quot;</tt> character can be used
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]283 in a name.</li>
284
285 <li>Unnamed values are represented as an unsigned numeric value with a '%'
286 prefix. For example, %12, %2, %44.</li>
287
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]288 <li>Constants, which are described in a <a href="#constants">section about
289 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]290</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]291
292<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
293don't need to worry about name clashes with reserved words, and the set of
294reserved words may be expanded in the future without penalty. Additionally,
295unnamed identifiers allow a compiler to quickly come up with a temporary
296variable without having to avoid symbol table conflicts.</p>
297
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]298<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]299languages. There are keywords for different opcodes
300('<tt><a href="#i_add">add</a></tt>',
301 '<tt><a href="#i_bitcast">bitcast</a></tt>',
302 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]303href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]304and others. These reserved words cannot conflict with variable names, because
305none of them start with a '%' character.</p>
306
307<p>Here is an example of LLVM code to multiply the integer variable
308'<tt>%X</tt>' by 8:</p>
309
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]310<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]311
312<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]313 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]314</pre>
315
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]316<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]317
318<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]319 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]320</pre>
321
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]322<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]323
324<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]325 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
326 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
327 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]328</pre>
329
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]330<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
331important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]332
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]333<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]334
335 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
336 line.</li>
337
338 <li>Unnamed temporaries are created when the result of a computation is not
339 assigned to a named value.</li>
340
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]341 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]342
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]343</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]344
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]345<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]346demonstrating instructions, we will follow an instruction with a comment that
347defines the type and name of value produced. Comments are shown in italic
348text.</p>
349
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]350</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]351
352<!-- *********************************************************************** -->
353<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
354<!-- *********************************************************************** -->
355
356<!-- ======================================================================= -->
357<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
358</div>
359
360<div class="doc_text">
361
362<p>LLVM programs are composed of "Module"s, each of which is a
363translation unit of the input programs. Each module consists of
364functions, global variables, and symbol table entries. Modules may be
365combined together with the LLVM linker, which merges function (and
366global variable) definitions, resolves forward declarations, and merges
367symbol table entries. Here is an example of the "hello world" module:</p>
368
369<pre><i>; Declare the string constant as a global constant...</i>
370<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]371 href="#globalvars">constant</a> <a href="#t_array">[13 x i8 ]</a> c"hello world\0A\00" <i>; [13 x i8 ]*</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]372
373<i>; External declaration of the puts function</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]374<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]375
376<i>; Definition of main function</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]377define i32 %main() { <i>; i32()* </i>
378 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]379 %cast210 = <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]380 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* %.LC0, i64 0, i64 0 <i>; i8 *</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]381
382 <i>; Call puts function to write out the string to stdout...</i>
383 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]384 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]385 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]386 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]387
388<p>This example is made up of a <a href="#globalvars">global variable</a>
389named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
390function, and a <a href="#functionstructure">function definition</a>
391for "<tt>main</tt>".</p>
392
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]393<p>In general, a module is made up of a list of global values,
394where both functions and global variables are global values. Global values are
395represented by a pointer to a memory location (in this case, a pointer to an
396array of char, and a pointer to a function), and have one of the following <a
397href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]398
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]399</div>
400
401<!-- ======================================================================= -->
402<div class="doc_subsection">
403 <a name="linkage">Linkage Types</a>
404</div>
405
406<div class="doc_text">
407
408<p>
409All Global Variables and Functions have one of the following types of linkage:
410</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]411
412<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]413
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]414 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]415
416 <dd>Global values with internal linkage are only directly accessible by
417 objects in the current module. In particular, linking code into a module with
418 an internal global value may cause the internal to be renamed as necessary to
419 avoid collisions. Because the symbol is internal to the module, all
420 references can be updated. This corresponds to the notion of the
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]421 '<tt>static</tt>' keyword in C.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]422 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]423
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]424 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]425
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]426 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
427 the same name when linkage occurs. This is typically used to implement
428 inline functions, templates, or other code which must be generated in each
429 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
430 allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]431 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]432
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]433 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]434
435 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
436 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]437 used for globals that may be emitted in multiple translation units, but that
438 are not guaranteed to be emitted into every translation unit that uses them.
439 One example of this are common globals in C, such as "<tt>int X;</tt>" at
440 global scope.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]441 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]442
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]443 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]444
445 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
446 pointer to array type. When two global variables with appending linkage are
447 linked together, the two global arrays are appended together. This is the
448 LLVM, typesafe, equivalent of having the system linker append together
449 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]450 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]451
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]452 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
453 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
454 until linked, if not linked, the symbol becomes null instead of being an
455 undefined reference.
456 </dd>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]457
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]458 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]459
460 <dd>If none of the above identifiers are used, the global is externally
461 visible, meaning that it participates in linkage and can be used to resolve
462 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]463 </dd>
Reid Spencerc8910842007-04-11 23:49:50 +0000[diff] [blame]464</dl>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]465
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]466 <p>
467 The next two types of linkage are targeted for Microsoft Windows platform
468 only. They are designed to support importing (exporting) symbols from (to)
469 DLLs.
470 </p>
471
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]472 <dl>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]473 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
474
475 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
476 or variable via a global pointer to a pointer that is set up by the DLL
477 exporting the symbol. On Microsoft Windows targets, the pointer name is
478 formed by combining <code>_imp__</code> and the function or variable name.
479 </dd>
480
481 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
482
483 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
484 pointer to a pointer in a DLL, so that it can be referenced with the
485 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
486 name is formed by combining <code>_imp__</code> and the function or variable
487 name.
488 </dd>
489
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]490</dl>
491
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]492<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]493variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
494variable and was linked with this one, one of the two would be renamed,
495preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
496external (i.e., lacking any linkage declarations), they are accessible
Reid Spencerac8d2762007-01-05 00:59:10 +0000[diff] [blame]497outside of the current module.</p>
498<p>It is illegal for a function <i>declaration</i>
499to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]500or <tt>extern_weak</tt>.</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]501
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]502</div>
503
504<!-- ======================================================================= -->
505<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]506 <a name="callingconv">Calling Conventions</a>
507</div>
508
509<div class="doc_text">
510
511<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
512and <a href="#i_invoke">invokes</a> can all have an optional calling convention
513specified for the call. The calling convention of any pair of dynamic
514caller/callee must match, or the behavior of the program is undefined. The
515following calling conventions are supported by LLVM, and more may be added in
516the future:</p>
517
518<dl>
519 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
520
521 <dd>This calling convention (the default if no other calling convention is
522 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]523 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencerc28d2bc2006-12-31 21:30:18 +0000[diff] [blame]524 prototype and implemented declaration of the function (as does normal C).
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]525 </dd>
526
527 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
528
529 <dd>This calling convention attempts to make calls as fast as possible
530 (e.g. by passing things in registers). This calling convention allows the
531 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]532 without having to conform to an externally specified ABI. Implementations of
533 this convention should allow arbitrary tail call optimization to be supported.
534 This calling convention does not support varargs and requires the prototype of
535 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]536 </dd>
537
538 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
539
540 <dd>This calling convention attempts to make code in the caller as efficient
541 as possible under the assumption that the call is not commonly executed. As
542 such, these calls often preserve all registers so that the call does not break
543 any live ranges in the caller side. This calling convention does not support
544 varargs and requires the prototype of all callees to exactly match the
545 prototype of the function definition.
546 </dd>
547
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]548 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]549
550 <dd>Any calling convention may be specified by number, allowing
551 target-specific calling conventions to be used. Target specific calling
552 conventions start at 64.
553 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]554</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]555
556<p>More calling conventions can be added/defined on an as-needed basis, to
557support pascal conventions or any other well-known target-independent
558convention.</p>
559
560</div>
561
562<!-- ======================================================================= -->
563<div class="doc_subsection">
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]564 <a name="visibility">Visibility Styles</a>
565</div>
566
567<div class="doc_text">
568
569<p>
570All Global Variables and Functions have one of the following visibility styles:
571</p>
572
573<dl>
574 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
575
576 <dd>On ELF, default visibility means that the declaration is visible to other
577 modules and, in shared libraries, means that the declared entity may be
578 overridden. On Darwin, default visibility means that the declaration is
579 visible to other modules. Default visibility corresponds to "external
580 linkage" in the language.
581 </dd>
582
583 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
584
585 <dd>Two declarations of an object with hidden visibility refer to the same
586 object if they are in the same shared object. Usually, hidden visibility
587 indicates that the symbol will not be placed into the dynamic symbol table,
588 so no other module (executable or shared library) can reference it
589 directly.
590 </dd>
591
592</dl>
593
594</div>
595
596<!-- ======================================================================= -->
597<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]598 <a name="globalvars">Global Variables</a>
599</div>
600
601<div class="doc_text">
602
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]603<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]604instead of run-time. Global variables may optionally be initialized, may have
605an explicit section to be placed in, and may
Lauro Ramos Venancioa4563362007-04-12 20:34:36 +0000[diff] [blame]606have an optional explicit alignment specified. A variable may be defined as
607"thread_local", which means that it will not be shared by threads (each thread
608will have a separated copy of the variable).
609A variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]610contents of the variable will <b>never</b> be modified (enabling better
611optimization, allowing the global data to be placed in the read-only section of
612an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]613cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]614
615<p>
616LLVM explicitly allows <em>declarations</em> of global variables to be marked
617constant, even if the final definition of the global is not. This capability
618can be used to enable slightly better optimization of the program, but requires
619the language definition to guarantee that optimizations based on the
620'constantness' are valid for the translation units that do not include the
621definition.
622</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]623
624<p>As SSA values, global variables define pointer values that are in
625scope (i.e. they dominate) all basic blocks in the program. Global
626variables always define a pointer to their "content" type because they
627describe a region of memory, and all memory objects in LLVM are
628accessed through pointers.</p>
629
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]630<p>LLVM allows an explicit section to be specified for globals. If the target
631supports it, it will emit globals to the section specified.</p>
632
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]633<p>An explicit alignment may be specified for a global. If not present, or if
634the alignment is set to zero, the alignment of the global is set by the target
635to whatever it feels convenient. If an explicit alignment is specified, the
636global is forced to have at least that much alignment. All alignments must be
637a power of 2.</p>
638
Chris Lattner68027ea2007-01-14 00:27:09 +0000[diff] [blame]639<p>For example, the following defines a global with an initializer, section,
640 and alignment:</p>
641
642<pre>
643 %G = constant float 1.0, section "foo", align 4
644</pre>
645
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]646</div>
647
648
649<!-- ======================================================================= -->
650<div class="doc_subsection">
651 <a name="functionstructure">Functions</a>
652</div>
653
654<div class="doc_text">
655
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]656<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
657an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]658<a href="#visibility">visibility style</a>, an optional
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]659<a href="#callingconv">calling convention</a>, a return type, an optional
660<a href="#paramattrs">parameter attribute</a> for the return type, a function
661name, a (possibly empty) argument list (each with optional
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]662<a href="#paramattrs">parameter attributes</a>), an optional section, an
663optional alignment, an opening curly brace, a list of basic blocks, and a
664closing curly brace.
665
666LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
667optional <a href="#linkage">linkage type</a>, an optional
668<a href="#visibility">visibility style</a>, an optional
669<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]670<a href="#paramattrs">parameter attribute</a> for the return type, a function
671name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]672
673<p>A function definition contains a list of basic blocks, forming the CFG for
674the function. Each basic block may optionally start with a label (giving the
675basic block a symbol table entry), contains a list of instructions, and ends
676with a <a href="#terminators">terminator</a> instruction (such as a branch or
677function return).</p>
678
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]679<p>The first basic block in a program is special in two ways: it is immediately
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]680executed on entrance to the function, and it is not allowed to have predecessor
681basic blocks (i.e. there can not be any branches to the entry block of a
682function). Because the block can have no predecessors, it also cannot have any
683<a href="#i_phi">PHI nodes</a>.</p>
684
685<p>LLVM functions are identified by their name and type signature. Hence, two
686functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]687considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]688appropriately.</p>
689
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]690<p>LLVM allows an explicit section to be specified for functions. If the target
691supports it, it will emit functions to the section specified.</p>
692
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]693<p>An explicit alignment may be specified for a function. If not present, or if
694the alignment is set to zero, the alignment of the function is set by the target
695to whatever it feels convenient. If an explicit alignment is specified, the
696function is forced to have at least that much alignment. All alignments must be
697a power of 2.</p>
698
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]699</div>
700
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]701<!-- ======================================================================= -->
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]702<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
703<div class="doc_text">
704 <p>The return type and each parameter of a function type may have a set of
705 <i>parameter attributes</i> associated with them. Parameter attributes are
706 used to communicate additional information about the result or parameters of
707 a function. Parameter attributes are considered to be part of the function
708 type so two functions types that differ only by the parameter attributes
709 are different function types.</p>
710
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]711 <p>Parameter attributes are simple keywords that follow the type specified. If
712 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]713 example:</p><pre>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]714 %someFunc = i16 (i8 sext %someParam) zext
715 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]716 <p>Note that the two function types above are unique because the parameter has
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]717 a different attribute (sext in the first one, zext in the second). Also note
718 that the attribute for the function result (zext) comes immediately after the
719 argument list.</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]720
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]721 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]722 <dl>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]723 <dt><tt>zext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]724 <dd>This indicates that the parameter should be zero extended just before
725 a call to this function.</dd>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]726 <dt><tt>sext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]727 <dd>This indicates that the parameter should be sign extended just before
728 a call to this function.</dd>
Anton Korobeynikov34d6dea2007-01-28 14:30:45 +0000[diff] [blame]729 <dt><tt>inreg</tt></dt>
730 <dd>This indicates that the parameter should be placed in register (if
Anton Korobeynikov66a8c8c2007-01-28 15:27:21 +0000[diff] [blame]731 possible) during assembling function call. Support for this attribute is
732 target-specific</dd>
Anton Korobeynikov34d6dea2007-01-28 14:30:45 +0000[diff] [blame]733 <dt><tt>sret</tt></dt>
Anton Korobeynikov66a8c8c2007-01-28 15:27:21 +0000[diff] [blame]734 <dd>This indicates that the parameter specifies the address of a structure
Reid Spencer67606122007-03-22 02:02:11 +0000[diff] [blame]735 that is the return value of the function in the source program.</dd>
Reid Spencer2dc52012007-03-22 02:18:56 +0000[diff] [blame]736 <dt><tt>noreturn</tt></dt>
737 <dd>This function attribute indicates that the function never returns. This
738 indicates to LLVM that every call to this function should be treated as if
739 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Reid Spencer67606122007-03-22 02:02:11 +0000[diff] [blame]740 <dt><tt>nounwind</tt></dt>
741 <dd>This function attribute indicates that the function type does not use
742 the unwind instruction and does not allow stack unwinding to propagate
743 through it.</dd>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]744 </dl>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]745
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]746</div>
747
748<!-- ======================================================================= -->
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]749<div class="doc_subsection">
Chris Lattner1eeeb0c2006-04-08 04:40:53 +0000[diff] [blame]750 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]751</div>
752
753<div class="doc_text">
754<p>
755Modules may contain "module-level inline asm" blocks, which corresponds to the
756GCC "file scope inline asm" blocks. These blocks are internally concatenated by
757LLVM and treated as a single unit, but may be separated in the .ll file if
758desired. The syntax is very simple:
759</p>
760
761<div class="doc_code"><pre>
Chris Lattner52599e12006-01-24 00:37:20 +0000[diff] [blame]762 module asm "inline asm code goes here"
763 module asm "more can go here"
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]764</pre></div>
765
766<p>The strings can contain any character by escaping non-printable characters.
767 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
768 for the number.
769</p>
770
771<p>
772 The inline asm code is simply printed to the machine code .s file when
773 assembly code is generated.
774</p>
775</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]776
Reid Spencerde151942007-02-19 23:54:10 +0000[diff] [blame]777<!-- ======================================================================= -->
778<div class="doc_subsection">
779 <a name="datalayout">Data Layout</a>
780</div>
781
782<div class="doc_text">
783<p>A module may specify a target specific data layout string that specifies how
Reid Spencerc8910842007-04-11 23:49:50 +0000[diff] [blame]784data is to be laid out in memory. The syntax for the data layout is simply:</p>
785<pre> target datalayout = "<i>layout specification</i>"</pre>
786<p>The <i>layout specification</i> consists of a list of specifications
787separated by the minus sign character ('-'). Each specification starts with a
788letter and may include other information after the letter to define some
789aspect of the data layout. The specifications accepted are as follows: </p>
Reid Spencerde151942007-02-19 23:54:10 +0000[diff] [blame]790<dl>
791 <dt><tt>E</tt></dt>
792 <dd>Specifies that the target lays out data in big-endian form. That is, the
793 bits with the most significance have the lowest address location.</dd>
794 <dt><tt>e</tt></dt>
795 <dd>Specifies that hte target lays out data in little-endian form. That is,
796 the bits with the least significance have the lowest address location.</dd>
797 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
798 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
799 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
800 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
801 too.</dd>
802 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
803 <dd>This specifies the alignment for an integer type of a given bit
804 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
805 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
806 <dd>This specifies the alignment for a vector type of a given bit
807 <i>size</i>.</dd>
808 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
809 <dd>This specifies the alignment for a floating point type of a given bit
810 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
811 (double).</dd>
812 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
813 <dd>This specifies the alignment for an aggregate type of a given bit
814 <i>size</i>.</dd>
815</dl>
816<p>When constructing the data layout for a given target, LLVM starts with a
817default set of specifications which are then (possibly) overriden by the
818specifications in the <tt>datalayout</tt> keyword. The default specifications
819are given in this list:</p>
820<ul>
821 <li><tt>E</tt> - big endian</li>
822 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
823 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
824 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
825 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
826 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
827 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
828 alignment of 64-bits</li>
829 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
830 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
831 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
832 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
833 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
834</ul>
835<p>When llvm is determining the alignment for a given type, it uses the
836following rules:
837<ol>
838 <li>If the type sought is an exact match for one of the specifications, that
839 specification is used.</li>
840 <li>If no match is found, and the type sought is an integer type, then the
841 smallest integer type that is larger than the bitwidth of the sought type is
842 used. If none of the specifications are larger than the bitwidth then the the
843 largest integer type is used. For example, given the default specifications
844 above, the i7 type will use the alignment of i8 (next largest) while both
845 i65 and i256 will use the alignment of i64 (largest specified).</li>
846 <li>If no match is found, and the type sought is a vector type, then the
847 largest vector type that is smaller than the sought vector type will be used
848 as a fall back. This happens because <128 x double> can be implemented in
849 terms of 64 <2 x double>, for example.</li>
850</ol>
851</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]852
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]853<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]854<div class="doc_section"> <a name="typesystem">Type System</a> </div>
855<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]856
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]857<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]858
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]859<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]860intermediate representation. Being typed enables a number of
861optimizations to be performed on the IR directly, without having to do
862extra analyses on the side before the transformation. A strong type
863system makes it easier to read the generated code and enables novel
864analyses and transformations that are not feasible to perform on normal
865three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]866
867</div>
868
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]869<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]870<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]871<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]872<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]873system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]874
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]875<table class="layout">
876 <tr class="layout">
877 <td class="left">
878 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]879 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]880 <tr><th>Type</th><th>Description</th></tr>
Duncan Sands8036ca42007-03-30 12:22:09 +0000[diff] [blame]881 <tr><td><tt><a name="t_void">void</a></tt></td><td>No value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]882 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
883 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]884 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]885 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]886 </tbody>
887 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]888 </td>
889 <td class="right">
890 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]891 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]892 <tr><th>Type</th><th>Description</th></tr>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]893 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]894 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
895 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]896 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]897 </tbody>
898 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]899 </td>
900 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]901</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]902</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]903
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]904<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]905<div class="doc_subsubsection"> <a name="t_classifications">Type
906Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]907<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]908<p>These different primitive types fall into a few useful
909classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]910
911<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]912 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]913 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]914 <tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]915 <td><a name="t_integer">integer</a></td>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]916 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]917 </tr>
918 <tr>
919 <td><a name="t_floating">floating point</a></td>
920 <td><tt>float, double</tt></td>
921 </tr>
922 <tr>
923 <td><a name="t_firstclass">first class</a></td>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]924 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]925 <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]926 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]927 </tr>
928 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]929</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]930
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]931<p>The <a href="#t_firstclass">first class</a> types are perhaps the
932most important. Values of these types are the only ones which can be
933produced by instructions, passed as arguments, or used as operands to
934instructions. This means that all structures and arrays must be
935manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]936</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]937
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]938<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]939<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]940
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]941<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]942
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]943<p>The real power in LLVM comes from the derived types in the system.
944This is what allows a programmer to represent arrays, functions,
945pointers, and other useful types. Note that these derived types may be
946recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]947
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]948</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]949
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]950<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]951<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]952
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]953<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]954
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]955<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]956
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]957<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]958sequentially in memory. The array type requires a size (number of
959elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]960
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]961<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]962
963<pre>
964 [&lt;# elements&gt; x &lt;elementtype&gt;]
965</pre>
966
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]967<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]968be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]969
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]970<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]971<table class="layout">
972 <tr class="layout">
973 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]974 <tt>[40 x i32 ]</tt><br/>
975 <tt>[41 x i32 ]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]976 <tt>[40 x i8]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]977 </td>
978 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]979 Array of 40 32-bit integer values.<br/>
980 Array of 41 32-bit integer values.<br/>
981 Array of 40 8-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]982 </td>
983 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]984</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]985<p>Here are some examples of multidimensional arrays:</p>
986<table class="layout">
987 <tr class="layout">
988 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]989 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]990 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]991 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]992 </td>
993 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]994 3x4 array of 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]995 12x10 array of single precision floating point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]996 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]997 </td>
998 </tr>
999</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]1000
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1001<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1002length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]1003LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1004As a special case, however, zero length arrays are recognized to be variable
1005length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1006type "{ i32, [0 x float]}", for example.</p>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]1007
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1008</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1009
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1010<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1011<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1012<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1013<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1014<p>The function type can be thought of as a function signature. It
1015consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]1016Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1017(which are structures of pointers to functions), for indirect function
1018calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]1019<p>
1020The return type of a function type cannot be an aggregate type.
1021</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1022<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1023<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1024<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]1025specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1026which indicates that the function takes a variable number of arguments.
1027Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1028 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1029<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1030<table class="layout">
1031 <tr class="layout">
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]1032 <td class="left"><tt>i32 (i32)</tt></td>
1033 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1034 </td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]1035 </tr><tr class="layout">
Reid Spencer7bf214d2007-01-15 18:28:34 +0000[diff] [blame]1036 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencerf17a0b72006-12-31 07:20:23 +0000[diff] [blame]1037 </tt></td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]1038 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1039 an <tt>i16</tt> that should be sign extended and a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1040 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]1041 <tt>float</tt>.
1042 </td>
1043 </tr><tr class="layout">
1044 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1045 <td class="left">A vararg function that takes at least one
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1046 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]1047 which returns an integer. This is the signature for <tt>printf</tt> in
1048 LLVM.
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1049 </td>
1050 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1051</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1052
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1053</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1054<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1055<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1056<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1057<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1058<p>The structure type is used to represent a collection of data members
1059together in memory. The packing of the field types is defined to match
1060the ABI of the underlying processor. The elements of a structure may
1061be any type that has a size.</p>
1062<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1063and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1064field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1065instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1066<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1067<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1068<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1069<table class="layout">
1070 <tr class="layout">
1071 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1072 <tt>{ i32, i32, i32 }</tt><br/>
1073 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1074 </td>
1075 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1076 a triple of three <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1077 A pair, where the first element is a <tt>float</tt> and the second element
1078 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1079 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1080 </td>
1081 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1082</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1083</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1084
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1085<!-- _______________________________________________________________________ -->
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1086<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1087</div>
1088<div class="doc_text">
1089<h5>Overview:</h5>
1090<p>The packed structure type is used to represent a collection of data members
1091together in memory. There is no padding between fields. Further, the alignment
1092of a packed structure is 1 byte. The elements of a packed structure may
1093be any type that has a size.</p>
1094<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1095and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1096field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1097instruction.</p>
1098<h5>Syntax:</h5>
1099<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1100<h5>Examples:</h5>
1101<table class="layout">
1102 <tr class="layout">
1103 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1104 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1105 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1106 </td>
1107 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1108 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1109 A pair, where the first element is a <tt>float</tt> and the second element
1110 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1111 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1112 </td>
1113 </tr>
1114</table>
1115</div>
1116
1117<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1118<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1119<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1120<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1121<p>As in many languages, the pointer type represents a pointer or
1122reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1123<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1124<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1125<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1126<table class="layout">
1127 <tr class="layout">
1128 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1129 <tt>[4x i32]*</tt><br/>
1130 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1131 </td>
1132 <td class="left">
1133 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1134 four <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1135 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1136 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1137 <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1138 </td>
1139 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1140</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1141</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1142
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1143<!-- _______________________________________________________________________ -->
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1144<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1145<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1146
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1147<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1148
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1149<p>A vector type is a simple derived type that represents a vector
1150of elements. Vector types are used when multiple primitive data
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1151are operated in parallel using a single instruction (SIMD).
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1152A vector type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]1153elements) and an underlying primitive data type. Vectors must have a power
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1154of two length (1, 2, 4, 8, 16 ...). Vector types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1155considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1156
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1157<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1158
1159<pre>
1160 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1161</pre>
1162
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1163<p>The number of elements is a constant integer value; elementtype may
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1164be any integer or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1165
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1166<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1167
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1168<table class="layout">
1169 <tr class="layout">
1170 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1171 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1172 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1173 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1174 </td>
1175 <td class="left">
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1176 Vector of 4 32-bit integer values.<br/>
1177 Vector of 8 floating-point values.<br/>
1178 Vector of 2 64-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1179 </td>
1180 </tr>
1181</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1182</div>
1183
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1184<!-- _______________________________________________________________________ -->
1185<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1186<div class="doc_text">
1187
1188<h5>Overview:</h5>
1189
1190<p>Opaque types are used to represent unknown types in the system. This
1191corresponds (for example) to the C notion of a foward declared structure type.
1192In LLVM, opaque types can eventually be resolved to any type (not just a
1193structure type).</p>
1194
1195<h5>Syntax:</h5>
1196
1197<pre>
1198 opaque
1199</pre>
1200
1201<h5>Examples:</h5>
1202
1203<table class="layout">
1204 <tr class="layout">
1205 <td class="left">
1206 <tt>opaque</tt>
1207 </td>
1208 <td class="left">
1209 An opaque type.<br/>
1210 </td>
1211 </tr>
1212</table>
1213</div>
1214
1215
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1216<!-- *********************************************************************** -->
1217<div class="doc_section"> <a name="constants">Constants</a> </div>
1218<!-- *********************************************************************** -->
1219
1220<div class="doc_text">
1221
1222<p>LLVM has several different basic types of constants. This section describes
1223them all and their syntax.</p>
1224
1225</div>
1226
1227<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1228<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1229
1230<div class="doc_text">
1231
1232<dl>
1233 <dt><b>Boolean constants</b></dt>
1234
1235 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1236 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1237 </dd>
1238
1239 <dt><b>Integer constants</b></dt>
1240
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1241 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1242 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1243 integer types.
1244 </dd>
1245
1246 <dt><b>Floating point constants</b></dt>
1247
1248 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1249 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1250 notation (see below). Floating point constants must have a <a
1251 href="#t_floating">floating point</a> type. </dd>
1252
1253 <dt><b>Null pointer constants</b></dt>
1254
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1255 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1256 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1257
1258</dl>
1259
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1260<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1261of floating point constants. For example, the form '<tt>double
12620x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
12634.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1264(and the only time that they are generated by the disassembler) is when a
1265floating point constant must be emitted but it cannot be represented as a
1266decimal floating point number. For example, NaN's, infinities, and other
1267special values are represented in their IEEE hexadecimal format so that
1268assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1269
1270</div>
1271
1272<!-- ======================================================================= -->
1273<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1274</div>
1275
1276<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1277<p>Aggregate constants arise from aggregation of simple constants
1278and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1279
1280<dl>
1281 <dt><b>Structure constants</b></dt>
1282
1283 <dd>Structure constants are represented with notation similar to structure
1284 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1285 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1286 where "<tt>%G</tt>" is declared as "<tt>%G = external global i32</tt>". Structure constants
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1287 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1288 types of elements must match those specified by the type.
1289 </dd>
1290
1291 <dt><b>Array constants</b></dt>
1292
1293 <dd>Array constants are represented with notation similar to array type
1294 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1295 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1296 constants must have <a href="#t_array">array type</a>, and the number and
1297 types of elements must match those specified by the type.
1298 </dd>
1299
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1300 <dt><b>Vector constants</b></dt>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1301
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1302 <dd>Vector constants are represented with notation similar to vector type
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1303 definitions (a comma separated list of elements, surrounded by
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1304 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1305 i32 11, i32 74, i32 100 &gt;</tt>". VEctor constants must have <a
1306 href="#t_vector">vector type</a>, and the number and types of elements must
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1307 match those specified by the type.
1308 </dd>
1309
1310 <dt><b>Zero initialization</b></dt>
1311
1312 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1313 value to zero of <em>any</em> type, including scalar and aggregate types.
1314 This is often used to avoid having to print large zero initializers (e.g. for
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1315 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1316 initializers.
1317 </dd>
1318</dl>
1319
1320</div>
1321
1322<!-- ======================================================================= -->
1323<div class="doc_subsection">
1324 <a name="globalconstants">Global Variable and Function Addresses</a>
1325</div>
1326
1327<div class="doc_text">
1328
1329<p>The addresses of <a href="#globalvars">global variables</a> and <a
1330href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1331constants. These constants are explicitly referenced when the <a
1332href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1333href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1334file:</p>
1335
1336<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1337 %X = global i32 17
1338 %Y = global i32 42
1339 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1340</pre>
1341
1342</div>
1343
1344<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1345<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1346<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1347 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1348 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1349 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1350
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1351 <p>Undefined values indicate to the compiler that the program is well defined
1352 no matter what value is used, giving the compiler more freedom to optimize.
1353 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1354</div>
1355
1356<!-- ======================================================================= -->
1357<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1358</div>
1359
1360<div class="doc_text">
1361
1362<p>Constant expressions are used to allow expressions involving other constants
1363to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1364href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1365that does not have side effects (e.g. load and call are not supported). The
1366following is the syntax for constant expressions:</p>
1367
1368<dl>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1369 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1370 <dd>Truncate a constant to another type. The bit size of CST must be larger
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1371 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1372
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1373 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1374 <dd>Zero extend a constant to another type. The bit size of CST must be
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1375 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1376
1377 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1378 <dd>Sign extend a constant to another type. The bit size of CST must be
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1379 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1380
1381 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1382 <dd>Truncate a floating point constant to another floating point type. The
1383 size of CST must be larger than the size of TYPE. Both types must be
1384 floating point.</dd>
1385
1386 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1387 <dd>Floating point extend a constant to another type. The size of CST must be
1388 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1389
1390 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1391 <dd>Convert a floating point constant to the corresponding unsigned integer
1392 constant. TYPE must be an integer type. CST must be floating point. If the
1393 value won't fit in the integer type, the results are undefined.</dd>
1394
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1395 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1396 <dd>Convert a floating point constant to the corresponding signed integer
1397 constant. TYPE must be an integer type. CST must be floating point. If the
1398 value won't fit in the integer type, the results are undefined.</dd>
1399
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1400 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1401 <dd>Convert an unsigned integer constant to the corresponding floating point
1402 constant. TYPE must be floating point. CST must be of integer type. If the
1403 value won't fit in the floating point type, the results are undefined.</dd>
1404
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1405 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1406 <dd>Convert a signed integer constant to the corresponding floating point
1407 constant. TYPE must be floating point. CST must be of integer type. If the
1408 value won't fit in the floating point type, the results are undefined.</dd>
1409
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1410 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1411 <dd>Convert a pointer typed constant to the corresponding integer constant
1412 TYPE must be an integer type. CST must be of pointer type. The CST value is
1413 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1414
1415 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1416 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1417 pointer type. CST must be of integer type. The CST value is zero extended,
1418 truncated, or unchanged to make it fit in a pointer size. This one is
1419 <i>really</i> dangerous!</dd>
1420
1421 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1422 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1423 identical (same number of bits). The conversion is done as if the CST value
1424 was stored to memory and read back as TYPE. In other words, no bits change
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1425 with this operator, just the type. This can be used for conversion of
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1426 vector types to any other type, as long as they have the same bit width. For
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1427 pointers it is only valid to cast to another pointer type.
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1428 </dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1429
1430 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1431
1432 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1433 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1434 instruction, the index list may have zero or more indexes, which are required
1435 to make sense for the type of "CSTPTR".</dd>
1436
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1437 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1438
1439 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1440 constants.</dd>
1441
1442 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1443 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1444
1445 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1446 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1447
1448 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1449
1450 <dd>Perform the <a href="#i_extractelement">extractelement
1451 operation</a> on constants.
1452
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1453 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1454
1455 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1456 operation</a> on constants.</dd>
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1457
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1458
1459 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1460
1461 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1462 operation</a> on constants.</dd>
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1463
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1464 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1465
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1466 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1467 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1468 binary</a> operations. The constraints on operands are the same as those for
1469 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1470 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1471</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1472</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1473
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1474<!-- *********************************************************************** -->
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1475<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1476<!-- *********************************************************************** -->
1477
1478<!-- ======================================================================= -->
1479<div class="doc_subsection">
1480<a name="inlineasm">Inline Assembler Expressions</a>
1481</div>
1482
1483<div class="doc_text">
1484
1485<p>
1486LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1487Module-Level Inline Assembly</a>) through the use of a special value. This
1488value represents the inline assembler as a string (containing the instructions
1489to emit), a list of operand constraints (stored as a string), and a flag that
1490indicates whether or not the inline asm expression has side effects. An example
1491inline assembler expression is:
1492</p>
1493
1494<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1495 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1496</pre>
1497
1498<p>
1499Inline assembler expressions may <b>only</b> be used as the callee operand of
1500a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1501</p>
1502
1503<pre>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]1504 %X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1505</pre>
1506
1507<p>
1508Inline asms with side effects not visible in the constraint list must be marked
1509as having side effects. This is done through the use of the
1510'<tt>sideeffect</tt>' keyword, like so:
1511</p>
1512
1513<pre>
1514 call void asm sideeffect "eieio", ""()
1515</pre>
1516
1517<p>TODO: The format of the asm and constraints string still need to be
1518documented here. Constraints on what can be done (e.g. duplication, moving, etc
1519need to be documented).
1520</p>
1521
1522</div>
1523
1524<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1525<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1526<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1527
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1528<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1529
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1530<p>The LLVM instruction set consists of several different
1531classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1532instructions</a>, <a href="#binaryops">binary instructions</a>,
1533<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1534 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1535instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1536
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1537</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1538
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1539<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1540<div class="doc_subsection"> <a name="terminators">Terminator
1541Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1542
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1543<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1544
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1545<p>As mentioned <a href="#functionstructure">previously</a>, every
1546basic block in a program ends with a "Terminator" instruction, which
1547indicates which block should be executed after the current block is
1548finished. These terminator instructions typically yield a '<tt>void</tt>'
1549value: they produce control flow, not values (the one exception being
1550the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1551<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1552 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1553instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1554the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1555 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1556 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1557
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1558</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1559
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1560<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1561<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1562Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1563<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1564<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1565<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1566 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1567</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1568<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1569<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1570value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1571<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1572returns a value and then causes control flow, and one that just causes
1573control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1574<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1575<p>The '<tt>ret</tt>' instruction may return any '<a
1576 href="#t_firstclass">first class</a>' type. Notice that a function is
1577not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1578instruction inside of the function that returns a value that does not
1579match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1580<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1581<p>When the '<tt>ret</tt>' instruction is executed, control flow
1582returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1583 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1584the instruction after the call. If the caller was an "<a
1585 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1586at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1587returns a value, that value shall set the call or invoke instruction's
1588return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1589<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1590<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1591 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1592</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1593</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1594<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1595<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1596<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1597<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1598<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1599</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1600<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1601<p>The '<tt>br</tt>' instruction is used to cause control flow to
1602transfer to a different basic block in the current function. There are
1603two forms of this instruction, corresponding to a conditional branch
1604and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1605<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1606<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1607single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Reid Spencerde151942007-02-19 23:54:10 +0000[diff] [blame]1608unconditional form of the '<tt>br</tt>' instruction takes a single
1609'<tt>label</tt>' value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1610<h5>Semantics:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1611<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1612argument is evaluated. If the value is <tt>true</tt>, control flows
1613to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1614control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1615<h5>Example:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1616<pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq, i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1617 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1618</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1619<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1620<div class="doc_subsubsection">
1621 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1622</div>
1623
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1624<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1625<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1626
1627<pre>
1628 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1629</pre>
1630
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1631<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1632
1633<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1634several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1635instruction, allowing a branch to occur to one of many possible
1636destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1637
1638
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1639<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1640
1641<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1642comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1643an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1644table is not allowed to contain duplicate constant entries.</p>
1645
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1646<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1647
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1648<p>The <tt>switch</tt> instruction specifies a table of values and
1649destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1650table is searched for the given value. If the value is found, control flow is
1651transfered to the corresponding destination; otherwise, control flow is
1652transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1653
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1654<h5>Implementation:</h5>
1655
1656<p>Depending on properties of the target machine and the particular
1657<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1658ways. For example, it could be generated as a series of chained conditional
1659branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1660
1661<h5>Example:</h5>
1662
1663<pre>
1664 <i>; Emulate a conditional br instruction</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1665 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1666 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1667
1668 <i>; Emulate an unconditional br instruction</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1669 switch i32 0, label %dest [ ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1670
1671 <i>; Implement a jump table:</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1672 switch i32 %val, label %otherwise [ i32 0, label %onzero
1673 i32 1, label %onone
1674 i32 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1675</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1676</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1677
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1678<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1679<div class="doc_subsubsection">
1680 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1681</div>
1682
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1683<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1684
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1685<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1686
1687<pre>
1688 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
Chris Lattner76b8a332006-05-14 18:23:06 +0000[diff] [blame]1689 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1690</pre>
1691
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1692<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1693
1694<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1695function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1696'<tt>normal</tt>' label or the
1697'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1698"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1699"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1700href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1701continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1702
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1703<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1704
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1705<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1706
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1707<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1708 <li>
Duncan Sands8036ca42007-03-30 12:22:09 +0000[diff] [blame]1709 The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1710 convention</a> the call should use. If none is specified, the call defaults
1711 to using C calling conventions.
1712 </li>
1713 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1714 function value being invoked. In most cases, this is a direct function
1715 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1716 an arbitrary pointer to function value.
1717 </li>
1718
1719 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1720 function to be invoked. </li>
1721
1722 <li>'<tt>function args</tt>': argument list whose types match the function
1723 signature argument types. If the function signature indicates the function
1724 accepts a variable number of arguments, the extra arguments can be
1725 specified. </li>
1726
1727 <li>'<tt>normal label</tt>': the label reached when the called function
1728 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1729
1730 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1731 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1732
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1733</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1734
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1735<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1736
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1737<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1738href="#i_call">call</a></tt>' instruction in most regards. The primary
1739difference is that it establishes an association with a label, which is used by
1740the runtime library to unwind the stack.</p>
1741
1742<p>This instruction is used in languages with destructors to ensure that proper
1743cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1744exception. Additionally, this is important for implementation of
1745'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1746
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1747<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1748<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1749 %retval = invoke i32 %Test(i32 15) to label %Continue
1750 unwind label %TestCleanup <i>; {i32}:retval set</i>
1751 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1752 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1753</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1754</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1755
1756
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1757<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1758
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1759<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1760Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1761
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1762<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1763
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1764<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1765<pre>
1766 unwind
1767</pre>
1768
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1769<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1770
1771<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1772at the first callee in the dynamic call stack which used an <a
1773href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1774primarily used to implement exception handling.</p>
1775
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1776<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1777
1778<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1779immediately halt. The dynamic call stack is then searched for the first <a
1780href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1781execution continues at the "exceptional" destination block specified by the
1782<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1783dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1784</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1785
1786<!-- _______________________________________________________________________ -->
1787
1788<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1789Instruction</a> </div>
1790
1791<div class="doc_text">
1792
1793<h5>Syntax:</h5>
1794<pre>
1795 unreachable
1796</pre>
1797
1798<h5>Overview:</h5>
1799
1800<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1801instruction is used to inform the optimizer that a particular portion of the
1802code is not reachable. This can be used to indicate that the code after a
1803no-return function cannot be reached, and other facts.</p>
1804
1805<h5>Semantics:</h5>
1806
1807<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1808</div>
1809
1810
1811
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1812<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1813<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1814<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1815<p>Binary operators are used to do most of the computation in a
1816program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1817produce a single value. The operands might represent
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1818multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1819The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1820necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1821<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1822</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1823<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1824<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1825Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1826<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1827<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1828<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1829</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1830<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1831<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1832<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1833<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1834 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1835 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1836Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1837<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1838<p>The value produced is the integer or floating point sum of the two
1839operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1840<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1841<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1842</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1843</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1844<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1845<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1846Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1847<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1848<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1849<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1850</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1851<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1852<p>The '<tt>sub</tt>' instruction returns the difference of its two
1853operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1854<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1855instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1856<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1857<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1858 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1859values.
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1860This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1861Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1862<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1863<p>The value produced is the integer or floating point difference of
1864the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1865<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1866<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1867 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1868</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1869</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1870<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1871<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1872Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1873<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1874<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1875<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1876</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1877<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1878<p>The '<tt>mul</tt>' instruction returns the product of its two
1879operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1880<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1881<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1882 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1883values.
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1884This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1885Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1886<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1887<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1888two operands.</p>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1889<p>Because the operands are the same width, the result of an integer
1890multiplication is the same whether the operands should be deemed unsigned or
1891signed.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1892<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1893<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1894</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1895</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1896<!-- _______________________________________________________________________ -->
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1897<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1898</a></div>
1899<div class="doc_text">
1900<h5>Syntax:</h5>
1901<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1902</pre>
1903<h5>Overview:</h5>
1904<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1905operands.</p>
1906<h5>Arguments:</h5>
1907<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1908<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1909types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1910of the values in which case the elements must be integers.</p>
1911<h5>Semantics:</h5>
1912<p>The value produced is the unsigned integer quotient of the two operands. This
1913instruction always performs an unsigned division operation, regardless of
1914whether the arguments are unsigned or not.</p>
1915<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1916<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1917</pre>
1918</div>
1919<!-- _______________________________________________________________________ -->
1920<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1921</a> </div>
1922<div class="doc_text">
1923<h5>Syntax:</h5>
1924<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1925</pre>
1926<h5>Overview:</h5>
1927<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1928operands.</p>
1929<h5>Arguments:</h5>
1930<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1931<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1932types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1933of the values in which case the elements must be integers.</p>
1934<h5>Semantics:</h5>
1935<p>The value produced is the signed integer quotient of the two operands. This
1936instruction always performs a signed division operation, regardless of whether
1937the arguments are signed or not.</p>
1938<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1939<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1940</pre>
1941</div>
1942<!-- _______________________________________________________________________ -->
1943<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1944Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1945<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1946<h5>Syntax:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1947<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1948</pre>
1949<h5>Overview:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1950<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1951operands.</p>
1952<h5>Arguments:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1953<p>The two arguments to the '<tt>div</tt>' instruction must be
1954<a href="#t_floating">floating point</a> values. Both arguments must have
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]1955identical types. This instruction can also take <a href="#t_vector">vector</a>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1956versions of the values in which case the elements must be floating point.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1957<h5>Semantics:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1958<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1959<h5>Example:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1960<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1961</pre>
1962</div>
1963<!-- _______________________________________________________________________ -->
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1964<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1965</div>
1966<div class="doc_text">
1967<h5>Syntax:</h5>
1968<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1969</pre>
1970<h5>Overview:</h5>
1971<p>The '<tt>urem</tt>' instruction returns the remainder from the
1972unsigned division of its two arguments.</p>
1973<h5>Arguments:</h5>
1974<p>The two arguments to the '<tt>urem</tt>' instruction must be
1975<a href="#t_integer">integer</a> values. Both arguments must have identical
1976types.</p>
1977<h5>Semantics:</h5>
1978<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1979This instruction always performs an unsigned division to get the remainder,
1980regardless of whether the arguments are unsigned or not.</p>
1981<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1982<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1983</pre>
1984
1985</div>
1986<!-- _______________________________________________________________________ -->
1987<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1988Instruction</a> </div>
1989<div class="doc_text">
1990<h5>Syntax:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1991<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1992</pre>
1993<h5>Overview:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1994<p>The '<tt>srem</tt>' instruction returns the remainder from the
1995signed division of its two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1996<h5>Arguments:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1997<p>The two arguments to the '<tt>srem</tt>' instruction must be
1998<a href="#t_integer">integer</a> values. Both arguments must have identical
1999types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2000<h5>Semantics:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]2001<p>This instruction returns the <i>remainder</i> of a division (where the result
Reid Spencerc9fdfc82007-03-24 22:23:39 +0000[diff] [blame]2002has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2003operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2004a value. For more information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2005 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
Reid Spencerc9fdfc82007-03-24 22:23:39 +0000[diff] [blame]2006Math Forum</a>. For a table of how this is implemented in various languages,
Reid Spencer64f5c6c2007-03-24 22:40:44 +0000[diff] [blame]2007please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
Reid Spencerc9fdfc82007-03-24 22:23:39 +0000[diff] [blame]2008Wikipedia: modulo operation</a>.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2009<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2010<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]2011</pre>
2012
2013</div>
2014<!-- _______________________________________________________________________ -->
2015<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2016Instruction</a> </div>
2017<div class="doc_text">
2018<h5>Syntax:</h5>
2019<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2020</pre>
2021<h5>Overview:</h5>
2022<p>The '<tt>frem</tt>' instruction returns the remainder from the
2023division of its two operands.</p>
2024<h5>Arguments:</h5>
2025<p>The two arguments to the '<tt>frem</tt>' instruction must be
2026<a href="#t_floating">floating point</a> values. Both arguments must have
2027identical types.</p>
2028<h5>Semantics:</h5>
2029<p>This instruction returns the <i>remainder</i> of a division.</p>
2030<h5>Example:</h5>
2031<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2032</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2033</div>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]2034
Reid Spencer8e11bf82007-02-02 13:57:07 +0000[diff] [blame]2035<!-- ======================================================================= -->
2036<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2037Operations</a> </div>
2038<div class="doc_text">
2039<p>Bitwise binary operators are used to do various forms of
2040bit-twiddling in a program. They are generally very efficient
2041instructions and can commonly be strength reduced from other
2042instructions. They require two operands, execute an operation on them,
2043and produce a single value. The resulting value of the bitwise binary
2044operators is always the same type as its first operand.</p>
2045</div>
2046
Reid Spencer569f2fa2007-01-31 21:39:12 +0000[diff] [blame]2047<!-- _______________________________________________________________________ -->
2048<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2049Instruction</a> </div>
2050<div class="doc_text">
2051<h5>Syntax:</h5>
2052<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2053</pre>
2054<h5>Overview:</h5>
2055<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2056the left a specified number of bits.</p>
2057<h5>Arguments:</h5>
2058<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2059 href="#t_integer">integer</a> type.</p>
2060<h5>Semantics:</h5>
2061<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
2062<h5>Example:</h5><pre>
2063 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2064 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2065 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
2066</pre>
2067</div>
2068<!-- _______________________________________________________________________ -->
2069<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2070Instruction</a> </div>
2071<div class="doc_text">
2072<h5>Syntax:</h5>
2073<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2074</pre>
2075
2076<h5>Overview:</h5>
2077<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2078operand shifted to the right a specified number of bits.</p>
2079
2080<h5>Arguments:</h5>
2081<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2082<a href="#t_integer">integer</a> type.</p>
2083
2084<h5>Semantics:</h5>
2085<p>This instruction always performs a logical shift right operation. The most
2086significant bits of the result will be filled with zero bits after the
2087shift.</p>
2088
2089<h5>Example:</h5>
2090<pre>
2091 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2092 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2093 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2094 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2095</pre>
2096</div>
2097
Reid Spencer8e11bf82007-02-02 13:57:07 +0000[diff] [blame]2098<!-- _______________________________________________________________________ -->
Reid Spencer569f2fa2007-01-31 21:39:12 +0000[diff] [blame]2099<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2100Instruction</a> </div>
2101<div class="doc_text">
2102
2103<h5>Syntax:</h5>
2104<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2105</pre>
2106
2107<h5>Overview:</h5>
2108<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2109operand shifted to the right a specified number of bits.</p>
2110
2111<h5>Arguments:</h5>
2112<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2113<a href="#t_integer">integer</a> type.</p>
2114
2115<h5>Semantics:</h5>
2116<p>This instruction always performs an arithmetic shift right operation,
2117The most significant bits of the result will be filled with the sign bit
2118of <tt>var1</tt>.</p>
2119
2120<h5>Example:</h5>
2121<pre>
2122 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2123 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2124 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2125 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
2126</pre>
2127</div>
2128
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2129<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2130<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2131Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2132<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2133<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2134<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2135</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2136<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2137<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2138its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2139<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2140<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2141 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2142identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2143<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2144<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2145<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2146<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2147<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2148 <tbody>
2149 <tr>
2150 <td>In0</td>
2151 <td>In1</td>
2152 <td>Out</td>
2153 </tr>
2154 <tr>
2155 <td>0</td>
2156 <td>0</td>
2157 <td>0</td>
2158 </tr>
2159 <tr>
2160 <td>0</td>
2161 <td>1</td>
2162 <td>0</td>
2163 </tr>
2164 <tr>
2165 <td>1</td>
2166 <td>0</td>
2167 <td>0</td>
2168 </tr>
2169 <tr>
2170 <td>1</td>
2171 <td>1</td>
2172 <td>1</td>
2173 </tr>
2174 </tbody>
2175</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2176</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2177<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2178<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2179 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2180 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2181</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2182</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2183<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2184<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2185<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2186<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2187<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2188</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2189<h5>Overview:</h5>
2190<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2191or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2192<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2193<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2194 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2195identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2196<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2197<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2198<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2199<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2200<table border="1" cellspacing="0" cellpadding="4">
2201 <tbody>
2202 <tr>
2203 <td>In0</td>
2204 <td>In1</td>
2205 <td>Out</td>
2206 </tr>
2207 <tr>
2208 <td>0</td>
2209 <td>0</td>
2210 <td>0</td>
2211 </tr>
2212 <tr>
2213 <td>0</td>
2214 <td>1</td>
2215 <td>1</td>
2216 </tr>
2217 <tr>
2218 <td>1</td>
2219 <td>0</td>
2220 <td>1</td>
2221 </tr>
2222 <tr>
2223 <td>1</td>
2224 <td>1</td>
2225 <td>1</td>
2226 </tr>
2227 </tbody>
2228</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2229</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2230<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2231<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2232 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2233 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2234</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2235</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2236<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2237<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2238Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2239<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2240<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2241<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2242</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2243<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2244<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2245or of its two operands. The <tt>xor</tt> is used to implement the
2246"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2247<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2248<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2249 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2250identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2251<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2252<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2253<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2254<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2255<table border="1" cellspacing="0" cellpadding="4">
2256 <tbody>
2257 <tr>
2258 <td>In0</td>
2259 <td>In1</td>
2260 <td>Out</td>
2261 </tr>
2262 <tr>
2263 <td>0</td>
2264 <td>0</td>
2265 <td>0</td>
2266 </tr>
2267 <tr>
2268 <td>0</td>
2269 <td>1</td>
2270 <td>1</td>
2271 </tr>
2272 <tr>
2273 <td>1</td>
2274 <td>0</td>
2275 <td>1</td>
2276 </tr>
2277 <tr>
2278 <td>1</td>
2279 <td>1</td>
2280 <td>0</td>
2281 </tr>
2282 </tbody>
2283</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2284</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2285<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2286<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2287<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2288 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2289 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2290 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2291</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2292</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2293
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2294<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2295<div class="doc_subsection">
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2296 <a name="vectorops">Vector Operations</a>
2297</div>
2298
2299<div class="doc_text">
2300
2301<p>LLVM supports several instructions to represent vector operations in a
2302target-independent manner. This instructions cover the element-access and
2303vector-specific operations needed to process vectors effectively. While LLVM
2304does directly support these vector operations, many sophisticated algorithms
2305will want to use target-specific intrinsics to take full advantage of a specific
2306target.</p>
2307
2308</div>
2309
2310<!-- _______________________________________________________________________ -->
2311<div class="doc_subsubsection">
2312 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2313</div>
2314
2315<div class="doc_text">
2316
2317<h5>Syntax:</h5>
2318
2319<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2320 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2321</pre>
2322
2323<h5>Overview:</h5>
2324
2325<p>
2326The '<tt>extractelement</tt>' instruction extracts a single scalar
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]2327element from a vector at a specified index.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2328</p>
2329
2330
2331<h5>Arguments:</h5>
2332
2333<p>
2334The first operand of an '<tt>extractelement</tt>' instruction is a
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]2335value of <a href="#t_vector">vector</a> type. The second operand is
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2336an index indicating the position from which to extract the element.
2337The index may be a variable.</p>
2338
2339<h5>Semantics:</h5>
2340
2341<p>
2342The result is a scalar of the same type as the element type of
2343<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2344<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2345results are undefined.
2346</p>
2347
2348<h5>Example:</h5>
2349
2350<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2351 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2352</pre>
2353</div>
2354
2355
2356<!-- _______________________________________________________________________ -->
2357<div class="doc_subsubsection">
2358 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2359</div>
2360
2361<div class="doc_text">
2362
2363<h5>Syntax:</h5>
2364
2365<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2366 &lt;result&gt; = insertelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, &lt;ty&gt; &lt;elt&gt, i32 &lt;idx&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2367</pre>
2368
2369<h5>Overview:</h5>
2370
2371<p>
2372The '<tt>insertelement</tt>' instruction inserts a scalar
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]2373element into a vector at a specified index.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2374</p>
2375
2376
2377<h5>Arguments:</h5>
2378
2379<p>
2380The first operand of an '<tt>insertelement</tt>' instruction is a
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]2381value of <a href="#t_vector">vector</a> type. The second operand is a
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2382scalar value whose type must equal the element type of the first
2383operand. The third operand is an index indicating the position at
2384which to insert the value. The index may be a variable.</p>
2385
2386<h5>Semantics:</h5>
2387
2388<p>
Reid Spencer485bad12007-02-15 03:07:05 +0000[diff] [blame]2389The result is a vector of the same type as <tt>val</tt>. Its
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2390element values are those of <tt>val</tt> except at position
2391<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2392exceeds the length of <tt>val</tt>, the results are undefined.
2393</p>
2394
2395<h5>Example:</h5>
2396
2397<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2398 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2399</pre>
2400</div>
2401
2402<!-- _______________________________________________________________________ -->
2403<div class="doc_subsubsection">
2404 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2405</div>
2406
2407<div class="doc_text">
2408
2409<h5>Syntax:</h5>
2410
2411<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2412 &lt;result&gt; = shufflevector &lt;n x &lt;ty&gt;&gt; &lt;v1&gt;, &lt;n x &lt;ty&gt;&gt; &lt;v2&gt;, &lt;n x i32&gt; &lt;mask&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2413</pre>
2414
2415<h5>Overview:</h5>
2416
2417<p>
2418The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2419from two input vectors, returning a vector of the same type.
2420</p>
2421
2422<h5>Arguments:</h5>
2423
2424<p>
2425The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2426with types that match each other and types that match the result of the
2427instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2428of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2429</p>
2430
2431<p>
2432The shuffle mask operand is required to be a constant vector with either
2433constant integer or undef values.
2434</p>
2435
2436<h5>Semantics:</h5>
2437
2438<p>
2439The elements of the two input vectors are numbered from left to right across
2440both of the vectors. The shuffle mask operand specifies, for each element of
2441the result vector, which element of the two input registers the result element
2442gets. The element selector may be undef (meaning "don't care") and the second
2443operand may be undef if performing a shuffle from only one vector.
2444</p>
2445
2446<h5>Example:</h5>
2447
2448<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2449 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2450 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2451 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2452 &lt;4 x i32&gt; &lt;i32 0, i32 1, i32 2, i32 3&gt; <i>; yields &lt;4 x i32&gt;</i> - Identity shuffle.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2453</pre>
2454</div>
2455
Tanya Lattner09474292006-04-14 19:24:33 +0000[diff] [blame]2456
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2457<!-- ======================================================================= -->
2458<div class="doc_subsection">
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2459 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2460</div>
2461
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2462<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2463
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2464<p>A key design point of an SSA-based representation is how it
2465represents memory. In LLVM, no memory locations are in SSA form, which
2466makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2467allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2468
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2469</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2470
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2471<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2472<div class="doc_subsubsection">
2473 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2474</div>
2475
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2476<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2477
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2478<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2479
2480<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2481 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2482</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2483
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2484<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2485
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2486<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2487heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2488
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2489<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2490
2491<p>The '<tt>malloc</tt>' instruction allocates
2492<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]2493bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2494appropriate type to the program. If "NumElements" is specified, it is the
2495number of elements allocated. If an alignment is specified, the value result
2496of the allocation is guaranteed to be aligned to at least that boundary. If
2497not specified, or if zero, the target can choose to align the allocation on any
2498convenient boundary.</p>
2499
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2500<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2501
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2502<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2503
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2504<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2505a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2506
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2507<h5>Example:</h5>
2508
2509<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2510 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2511
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2512 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2513 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2514 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2515 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2516 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2517</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2518</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2519
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2520<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2521<div class="doc_subsubsection">
2522 <a name="i_free">'<tt>free</tt>' Instruction</a>
2523</div>
2524
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2525<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2526
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2527<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2528
2529<pre>
2530 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2531</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2532
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2533<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2534
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2535<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2536memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2537
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2538<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2539
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2540<p>'<tt>value</tt>' shall be a pointer value that points to a value
2541that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2542instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2543
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2544<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2545
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2546<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2547after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2548
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2549<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2550
2551<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2552 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2553 free [4 x i8]* %array
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2554</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2555</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2556
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2557<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2558<div class="doc_subsubsection">
2559 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2560</div>
2561
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2562<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2563
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2564<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2565
2566<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2567 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2568</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2569
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2570<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2571
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2572<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2573stack frame of the procedure that is live until the current function
2574returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2575
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2576<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2577
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2578<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2579bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2580appropriate type to the program. If "NumElements" is specified, it is the
2581number of elements allocated. If an alignment is specified, the value result
2582of the allocation is guaranteed to be aligned to at least that boundary. If
2583not specified, or if zero, the target can choose to align the allocation on any
2584convenient boundary.</p>
2585
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2586<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2587
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2588<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2589
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2590<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2591memory is automatically released when the function returns. The '<tt>alloca</tt>'
2592instruction is commonly used to represent automatic variables that must
2593have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]2594 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2595instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2596
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2597<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2598
2599<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2600 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2601 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2602 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2603 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2604</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2605</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2606
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2607<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2608<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2609Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2610<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2611<h5>Syntax:</h5>
Christopher Lamb2330e4d2007-04-21 08:16:25 +0000[diff] [blame]2612<pre> &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]<br> &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]<br></pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2613<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2614<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2615<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2616<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2617address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2618 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2619marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2620the number or order of execution of this <tt>load</tt> with other
2621volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2622instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2623<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2624<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2625<h5>Examples:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2626<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2627 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2628 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2629 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2630</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2631</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2632<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2633<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2634Instruction</a> </div>
Reid Spencer035ab572006-11-09 21:18:01 +0000[diff] [blame]2635<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2636<h5>Syntax:</h5>
Christopher Lamb2330e4d2007-04-21 08:16:25 +0000[diff] [blame]2637<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
2638 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;] <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2639</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2640<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2641<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2642<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2643<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2644to store and an address in which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2645operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2646operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2647optimizer is not allowed to modify the number or order of execution of
2648this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2649 href="#i_store">store</a></tt> instructions.</p>
2650<h5>Semantics:</h5>
2651<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2652at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2653<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2654<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2655 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2656 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2657 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2658</pre>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2659</div>
2660
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2661<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2662<div class="doc_subsubsection">
2663 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2664</div>
2665
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2666<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2667<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2668<pre>
2669 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2670</pre>
2671
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2672<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2673
2674<p>
2675The '<tt>getelementptr</tt>' instruction is used to get the address of a
2676subelement of an aggregate data structure.</p>
2677
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2678<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2679
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2680<p>This instruction takes a list of integer operands that indicate what
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2681elements of the aggregate object to index to. The actual types of the arguments
2682provided depend on the type of the first pointer argument. The
2683'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2684levels of a structure or to a specific index in an array. When indexing into a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2685structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2686into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2687be sign extended to 64-bit values.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2688
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2689<p>For example, let's consider a C code fragment and how it gets
2690compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2691
2692<pre>
2693 struct RT {
2694 char A;
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2695 i32 B[10][20];
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2696 char C;
2697 };
2698 struct ST {
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2699 i32 X;
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2700 double Y;
2701 struct RT Z;
2702 };
2703
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2704 define i32 *foo(struct ST *s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2705 return &amp;s[1].Z.B[5][13];
2706 }
2707</pre>
2708
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2709<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2710
2711<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2712 %RT = type { i8 , [10 x [20 x i32]], i8 }
2713 %ST = type { i32, double, %RT }
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2714
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2715 define i32* %foo(%ST* %s) {
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2716 entry:
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2717 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2718 ret i32* %reg
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2719 }
2720</pre>
2721
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2722<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2723
2724<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2725on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2726and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
Reid Spencer42ddd842006-12-03 16:53:48 +0000[diff] [blame]2727<a href="#t_integer">integer</a> type but the value will always be sign extended
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2728to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencer42ddd842006-12-03 16:53:48 +0000[diff] [blame]2729<b>constants</b>.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2730
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2731<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2732type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2733}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2734the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2735i8 }</tt>' type, another structure. The third index indexes into the second
2736element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2737array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2738'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2739to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2740
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2741<p>Note that it is perfectly legal to index partially through a
2742structure, returning a pointer to an inner element. Because of this,
2743the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2744
2745<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2746 define i32* %foo(%ST* %s) {
2747 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2748 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2749 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2750 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2751 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2752 ret i32* %t5
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2753 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2754</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2755
2756<p>Note that it is undefined to access an array out of bounds: array and
2757pointer indexes must always be within the defined bounds of the array type.
2758The one exception for this rules is zero length arrays. These arrays are
2759defined to be accessible as variable length arrays, which requires access
2760beyond the zero'th element.</p>
2761
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2762<p>The getelementptr instruction is often confusing. For some more insight
2763into how it works, see <a href="GetElementPtr.html">the getelementptr
2764FAQ</a>.</p>
2765
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2766<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2767
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2768<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2769 <i>; yields [12 x i8]*:aptr</i>
2770 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2771</pre>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2772</div>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2773
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2774<!-- ======================================================================= -->
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2775<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2776</div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2777<div class="doc_text">
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2778<p>The instructions in this category are the conversion instructions (casting)
2779which all take a single operand and a type. They perform various bit conversions
2780on the operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2781</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2782
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2783<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2784<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2785 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2786</div>
2787<div class="doc_text">
2788
2789<h5>Syntax:</h5>
2790<pre>
2791 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2792</pre>
2793
2794<h5>Overview:</h5>
2795<p>
2796The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2797</p>
2798
2799<h5>Arguments:</h5>
2800<p>
2801The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2802be an <a href="#t_integer">integer</a> type, and a type that specifies the size
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2803and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2804type. The bit size of <tt>value</tt> must be larger than the bit size of
2805<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2806
2807<h5>Semantics:</h5>
2808<p>
2809The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2810and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2811larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2812It will always truncate bits.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2813
2814<h5>Example:</h5>
2815<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2816 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2817 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2818 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2819</pre>
2820</div>
2821
2822<!-- _______________________________________________________________________ -->
2823<div class="doc_subsubsection">
2824 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2825</div>
2826<div class="doc_text">
2827
2828<h5>Syntax:</h5>
2829<pre>
2830 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2831</pre>
2832
2833<h5>Overview:</h5>
2834<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2835<tt>ty2</tt>.</p>
2836
2837
2838<h5>Arguments:</h5>
2839<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2840<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2841also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2842<tt>value</tt> must be smaller than the bit size of the destination type,
2843<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2844
2845<h5>Semantics:</h5>
2846<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2847bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2848the operand and the type are the same size, no bit filling is done and the
2849cast is considered a <i>no-op cast</i> because no bits change (only the type
2850changes).</p>
2851
Reid Spencerb5929522007-01-12 15:46:11 +0000[diff] [blame]2852<p>When zero extending from i1, the result will always be either 0 or 1.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2853
2854<h5>Example:</h5>
2855<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2856 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2857 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2858</pre>
2859</div>
2860
2861<!-- _______________________________________________________________________ -->
2862<div class="doc_subsubsection">
2863 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2864</div>
2865<div class="doc_text">
2866
2867<h5>Syntax:</h5>
2868<pre>
2869 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2870</pre>
2871
2872<h5>Overview:</h5>
2873<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2874
2875<h5>Arguments:</h5>
2876<p>
2877The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2878<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2879also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2880<tt>value</tt> must be smaller than the bit size of the destination type,
2881<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2882
2883<h5>Semantics:</h5>
2884<p>
2885The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2886bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2887the type <tt>ty2</tt>. When the the operand and the type are the same size,
2888no bit filling is done and the cast is considered a <i>no-op cast</i> because
2889no bits change (only the type changes).</p>
2890
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2891<p>When sign extending from i1, the extension always results in -1 or 0.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2892
2893<h5>Example:</h5>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2894<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2895 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2896 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2897</pre>
2898</div>
2899
2900<!-- _______________________________________________________________________ -->
2901<div class="doc_subsubsection">
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2902 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2903</div>
2904
2905<div class="doc_text">
2906
2907<h5>Syntax:</h5>
2908
2909<pre>
2910 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2911</pre>
2912
2913<h5>Overview:</h5>
2914<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2915<tt>ty2</tt>.</p>
2916
2917
2918<h5>Arguments:</h5>
2919<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2920 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2921cast it to. The size of <tt>value</tt> must be larger than the size of
2922<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2923<i>no-op cast</i>.</p>
2924
2925<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2926<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2927<a href="#t_floating">floating point</a> type to a smaller
2928<a href="#t_floating">floating point</a> type. If the value cannot fit within
2929the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2930
2931<h5>Example:</h5>
2932<pre>
2933 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2934 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2935</pre>
2936</div>
2937
2938<!-- _______________________________________________________________________ -->
2939<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2940 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2941</div>
2942<div class="doc_text">
2943
2944<h5>Syntax:</h5>
2945<pre>
2946 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2947</pre>
2948
2949<h5>Overview:</h5>
2950<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2951floating point value.</p>
2952
2953<h5>Arguments:</h5>
2954<p>The '<tt>fpext</tt>' instruction takes a
2955<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2956and a <a href="#t_floating">floating point</a> type to cast it to. The source
2957type must be smaller than the destination type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2958
2959<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2960<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
Duncan Sands8036ca42007-03-30 12:22:09 +0000[diff] [blame]2961<a href="#t_floating">floating point</a> type to a larger
2962<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2963used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]2964<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2965
2966<h5>Example:</h5>
2967<pre>
2968 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2969 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2970</pre>
2971</div>
2972
2973<!-- _______________________________________________________________________ -->
2974<div class="doc_subsubsection">
Reid Spencer24d6da52007-01-21 00:29:26 +0000[diff] [blame]2975 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2976</div>
2977<div class="doc_text">
2978
2979<h5>Syntax:</h5>
2980<pre>
2981 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2982</pre>
2983
2984<h5>Overview:</h5>
2985<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2986unsigned integer equivalent of type <tt>ty2</tt>.
2987</p>
2988
2989<h5>Arguments:</h5>
2990<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2991<a href="#t_floating">floating point</a> value, and a type to cast it to, which
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2992must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2993
2994<h5>Semantics:</h5>
2995<p> The '<tt>fp2uint</tt>' instruction converts its
2996<a href="#t_floating">floating point</a> operand into the nearest (rounding
2997towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2998the results are undefined.</p>
2999
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3000<p>When converting to i1, the conversion is done as a comparison against
3001zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3002If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3003
3004<h5>Example:</h5>
3005<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3006 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
3007 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3008 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3009</pre>
3010</div>
3011
3012<!-- _______________________________________________________________________ -->
3013<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3014 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3015</div>
3016<div class="doc_text">
3017
3018<h5>Syntax:</h5>
3019<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3020 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3021</pre>
3022
3023<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3024<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3025<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3026</p>
3027
3028
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3029<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3030<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3031<a href="#t_floating">floating point</a> value, and a type to cast it to, which
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3032must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3033
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3034<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3035<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3036<a href="#t_floating">floating point</a> operand into the nearest (rounding
3037towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3038the results are undefined.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3039
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3040<p>When converting to i1, the conversion is done as a comparison against
3041zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3042If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3043
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]3044<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3045<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3046 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
3047 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3048 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3049</pre>
3050</div>
3051
3052<!-- _______________________________________________________________________ -->
3053<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3054 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3055</div>
3056<div class="doc_text">
3057
3058<h5>Syntax:</h5>
3059<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3060 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3061</pre>
3062
3063<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3064<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3065integer and converts that value to the <tt>ty2</tt> type.</p>
3066
3067
3068<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3069<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be an
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3070<a href="#t_integer">integer</a> value, and a type to cast it to, which must
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3071be a <a href="#t_floating">floating point</a> type.</p>
3072
3073<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3074<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3075integer quantity and converts it to the corresponding floating point value. If
3076the value cannot fit in the floating point value, the results are undefined.</p>
3077
3078
3079<h5>Example:</h5>
3080<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3081 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3082 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3083</pre>
3084</div>
3085
3086<!-- _______________________________________________________________________ -->
3087<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3088 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3089</div>
3090<div class="doc_text">
3091
3092<h5>Syntax:</h5>
3093<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3094 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3095</pre>
3096
3097<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3098<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3099integer and converts that value to the <tt>ty2</tt> type.</p>
3100
3101<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3102<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be an
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3103<a href="#t_integer">integer</a> value, and a type to cast it to, which must be
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3104a <a href="#t_floating">floating point</a> type.</p>
3105
3106<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3107<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3108integer quantity and converts it to the corresponding floating point value. If
3109the value cannot fit in the floating point value, the results are undefined.</p>
3110
3111<h5>Example:</h5>
3112<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3113 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3114 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3115</pre>
3116</div>
3117
3118<!-- _______________________________________________________________________ -->
3119<div class="doc_subsubsection">
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3120 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3121</div>
3122<div class="doc_text">
3123
3124<h5>Syntax:</h5>
3125<pre>
3126 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3127</pre>
3128
3129<h5>Overview:</h5>
3130<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3131the integer type <tt>ty2</tt>.</p>
3132
3133<h5>Arguments:</h5>
3134<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
Duncan Sands8036ca42007-03-30 12:22:09 +0000[diff] [blame]3135must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3136<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3137
3138<h5>Semantics:</h5>
3139<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3140<tt>ty2</tt> by interpreting the pointer value as an integer and either
3141truncating or zero extending that value to the size of the integer type. If
3142<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3143<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3144are the same size, then nothing is done (<i>no-op cast</i>).</p>
3145
3146<h5>Example:</h5>
3147<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3148 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3149 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3150</pre>
3151</div>
3152
3153<!-- _______________________________________________________________________ -->
3154<div class="doc_subsubsection">
3155 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3156</div>
3157<div class="doc_text">
3158
3159<h5>Syntax:</h5>
3160<pre>
3161 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3162</pre>
3163
3164<h5>Overview:</h5>
3165<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3166a pointer type, <tt>ty2</tt>.</p>
3167
3168<h5>Arguments:</h5>
Duncan Sands8036ca42007-03-30 12:22:09 +0000[diff] [blame]3169<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3170value to cast, and a type to cast it to, which must be a
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]3171<a href="#t_pointer">pointer</a> type.
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3172
3173<h5>Semantics:</h5>
3174<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3175<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3176the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3177size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3178the size of a pointer then a zero extension is done. If they are the same size,
3179nothing is done (<i>no-op cast</i>).</p>
3180
3181<h5>Example:</h5>
3182<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3183 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3184 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3185 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3186</pre>
3187</div>
3188
3189<!-- _______________________________________________________________________ -->
3190<div class="doc_subsubsection">
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3191 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3192</div>
3193<div class="doc_text">
3194
3195<h5>Syntax:</h5>
3196<pre>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3197 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3198</pre>
3199
3200<h5>Overview:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3201<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3202<tt>ty2</tt> without changing any bits.</p>
3203
3204<h5>Arguments:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3205<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3206a first class value, and a type to cast it to, which must also be a <a
3207 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencer19b569f2007-01-09 20:08:58 +0000[diff] [blame]3208and the destination type, <tt>ty2</tt>, must be identical. If the source
3209type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3210
3211<h5>Semantics:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3212<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3213<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3214this conversion. The conversion is done as if the <tt>value</tt> had been
3215stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3216converted to other pointer types with this instruction. To convert pointers to
3217other types, use the <a href="#i_inttoptr">inttoptr</a> or
3218<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3219
3220<h5>Example:</h5>
3221<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3222 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3223 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3224 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]3225</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3226</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3227
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3228<!-- ======================================================================= -->
3229<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3230<div class="doc_text">
3231<p>The instructions in this category are the "miscellaneous"
3232instructions, which defy better classification.</p>
3233</div>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3234
3235<!-- _______________________________________________________________________ -->
3236<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3237</div>
3238<div class="doc_text">
3239<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3240<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3241<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3242</pre>
3243<h5>Overview:</h5>
3244<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3245of its two integer operands.</p>
3246<h5>Arguments:</h5>
3247<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3248the condition code which indicates the kind of comparison to perform. It is not
3249a value, just a keyword. The possibilities for the condition code are:
3250<ol>
3251 <li><tt>eq</tt>: equal</li>
3252 <li><tt>ne</tt>: not equal </li>
3253 <li><tt>ugt</tt>: unsigned greater than</li>
3254 <li><tt>uge</tt>: unsigned greater or equal</li>
3255 <li><tt>ult</tt>: unsigned less than</li>
3256 <li><tt>ule</tt>: unsigned less or equal</li>
3257 <li><tt>sgt</tt>: signed greater than</li>
3258 <li><tt>sge</tt>: signed greater or equal</li>
3259 <li><tt>slt</tt>: signed less than</li>
3260 <li><tt>sle</tt>: signed less or equal</li>
3261</ol>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3262<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3263<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3264<h5>Semantics:</h5>
3265<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3266the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3267yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3268<ol>
3269 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3270 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3271 </li>
3272 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3273 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3274 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3275 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3276 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3277 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3278 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3279 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3280 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3281 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3282 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3283 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3284 <li><tt>sge</tt>: interprets the operands as signed values and yields
3285 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3286 <li><tt>slt</tt>: interprets the operands as signed values and yields
3287 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3288 <li><tt>sle</tt>: interprets the operands as signed values and yields
3289 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3290</ol>
3291<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3292values are treated as integers and then compared.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3293
3294<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3295<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3296 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3297 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3298 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3299 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3300 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3301</pre>
3302</div>
3303
3304<!-- _______________________________________________________________________ -->
3305<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3306</div>
3307<div class="doc_text">
3308<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3309<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3310<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3311</pre>
3312<h5>Overview:</h5>
3313<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3314of its floating point operands.</p>
3315<h5>Arguments:</h5>
3316<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3317the condition code which indicates the kind of comparison to perform. It is not
3318a value, just a keyword. The possibilities for the condition code are:
3319<ol>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3320 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3321 <li><tt>oeq</tt>: ordered and equal</li>
3322 <li><tt>ogt</tt>: ordered and greater than </li>
3323 <li><tt>oge</tt>: ordered and greater than or equal</li>
3324 <li><tt>olt</tt>: ordered and less than </li>
3325 <li><tt>ole</tt>: ordered and less than or equal</li>
3326 <li><tt>one</tt>: ordered and not equal</li>
3327 <li><tt>ord</tt>: ordered (no nans)</li>
3328 <li><tt>ueq</tt>: unordered or equal</li>
3329 <li><tt>ugt</tt>: unordered or greater than </li>
3330 <li><tt>uge</tt>: unordered or greater than or equal</li>
3331 <li><tt>ult</tt>: unordered or less than </li>
3332 <li><tt>ule</tt>: unordered or less than or equal</li>
3333 <li><tt>une</tt>: unordered or not equal</li>
3334 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3335 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3336</ol>
Reid Spencer93a49852006-12-06 07:08:07 +0000[diff] [blame]3337<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3338<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3339<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3340<a href="#t_floating">floating point</a> typed. They must have identical
3341types.</p>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3342<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3343<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3344<h5>Semantics:</h5>
3345<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3346the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3347yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3348<ol>
3349 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3350 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3351 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3352 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3353 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3354 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3355 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3356 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3357 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3358 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3359 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3360 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3361 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3362 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3363 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3364 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3365 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3366 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3367 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3368 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3369 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3370 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3371 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3372 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3373 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3374 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3375 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3376 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3377</ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3378
3379<h5>Example:</h5>
3380<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3381 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3382 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3383 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3384</pre>
3385</div>
3386
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3387<!-- _______________________________________________________________________ -->
3388<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3389Instruction</a> </div>
3390<div class="doc_text">
3391<h5>Syntax:</h5>
3392<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3393<h5>Overview:</h5>
3394<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3395the SSA graph representing the function.</p>
3396<h5>Arguments:</h5>
3397<p>The type of the incoming values are specified with the first type
3398field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3399as arguments, with one pair for each predecessor basic block of the
3400current block. Only values of <a href="#t_firstclass">first class</a>
3401type may be used as the value arguments to the PHI node. Only labels
3402may be used as the label arguments.</p>
3403<p>There must be no non-phi instructions between the start of a basic
3404block and the PHI instructions: i.e. PHI instructions must be first in
3405a basic block.</p>
3406<h5>Semantics:</h5>
3407<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3408value specified by the parameter, depending on which basic block we
3409came from in the last <a href="#terminators">terminator</a> instruction.</p>
3410<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3411<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add i32 %indvar, 1<br> br label %Loop<br></pre>
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3412</div>
3413
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3414<!-- _______________________________________________________________________ -->
3415<div class="doc_subsubsection">
3416 <a name="i_select">'<tt>select</tt>' Instruction</a>
3417</div>
3418
3419<div class="doc_text">
3420
3421<h5>Syntax:</h5>
3422
3423<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3424 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3425</pre>
3426
3427<h5>Overview:</h5>
3428
3429<p>
3430The '<tt>select</tt>' instruction is used to choose one value based on a
3431condition, without branching.
3432</p>
3433
3434
3435<h5>Arguments:</h5>
3436
3437<p>
3438The '<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.
3439</p>
3440
3441<h5>Semantics:</h5>
3442
3443<p>
3444If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3445value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3446</p>
3447
3448<h5>Example:</h5>
3449
3450<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3451 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3452</pre>
3453</div>
3454
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]3455
3456<!-- _______________________________________________________________________ -->
3457<div class="doc_subsubsection">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3458 <a name="i_call">'<tt>call</tt>' Instruction</a>
3459</div>
3460
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3461<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3462
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3463<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3464<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3465 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3466</pre>
3467
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3468<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3469
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3470<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3471
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3472<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3473
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3474<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3475
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3476<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3477 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3478 <p>The optional "tail" marker indicates whether the callee function accesses
3479 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3480 function call is eligible for tail call optimization. Note that calls may
3481 be marked "tail" even if they do not occur before a <a
3482 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3483 </li>
3484 <li>
Duncan Sands8036ca42007-03-30 12:22:09 +0000[diff] [blame]3485 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3486 convention</a> the call should use. If none is specified, the call defaults
3487 to using C calling conventions.
3488 </li>
3489 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3490 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3491 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3492 signature. This type can be omitted if the function is not varargs and
3493 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3494 </li>
3495 <li>
3496 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3497 be invoked. In most cases, this is a direct function invocation, but
3498 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3499 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3500 </li>
3501 <li>
3502 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]3503 function signature argument types. All arguments must be of
3504 <a href="#t_firstclass">first class</a> type. If the function signature
3505 indicates the function accepts a variable number of arguments, the extra
3506 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3507 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3508</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3509
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3510<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3511
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3512<p>The '<tt>call</tt>' instruction is used to cause control flow to
3513transfer to a specified function, with its incoming arguments bound to
3514the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3515instruction in the called function, control flow continues with the
3516instruction after the function call, and the return value of the
3517function is bound to the result argument. This is a simpler case of
3518the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3519
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3520<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3521
3522<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3523 %retval = call i32 %test(i32 %argc)
3524 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3525 %X = tail call i32 %foo()
3526 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3527</pre>
3528
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3529</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3530
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3531<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3532<div class="doc_subsubsection">
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3533 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3534</div>
3535
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3536<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3537
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3538<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3539
3540<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3541 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3542</pre>
3543
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3544<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3545
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3546<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3547the "variable argument" area of a function call. It is used to implement the
3548<tt>va_arg</tt> macro in C.</p>
3549
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3550<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3551
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3552<p>This instruction takes a <tt>va_list*</tt> value and the type of
3553the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3554increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3555actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3556
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3557<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3558
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3559<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3560type from the specified <tt>va_list</tt> and causes the
3561<tt>va_list</tt> to point to the next argument. For more information,
3562see the variable argument handling <a href="#int_varargs">Intrinsic
3563Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3564
3565<p>It is legal for this instruction to be called in a function which does not
3566take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3567function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3568
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3569<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3570href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3571argument.</p>
3572
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3573<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3574
3575<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3576
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3577</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3578
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3579<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3580<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3581<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3582
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3583<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3584
3585<p>LLVM supports the notion of an "intrinsic function". These functions have
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]3586well known names and semantics and are required to follow certain restrictions.
3587Overall, these intrinsics represent an extension mechanism for the LLVM
3588language that does not require changing all of the transformations in LLVM to
3589add to the language (or the bytecode reader/writer, the parser,
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3590etc...).</p>
3591
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3592<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3593prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3594this. Intrinsic functions must always be external functions: you cannot define
3595the body of intrinsic functions. Intrinsic functions may only be used in call
3596or invoke instructions: it is illegal to take the address of an intrinsic
3597function. Additionally, because intrinsic functions are part of the LLVM
3598language, it is required that they all be documented here if any are added.</p>
3599
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]3600<p>Some intrinsic functions can be overloaded. That is, the intrinsic represents
3601a family of functions that perform the same operation but on different data
3602types. This is most frequent with the integer types. Since LLVM can represent
3603over 8 million different integer types, there is a way to declare an intrinsic
3604that can be overloaded based on its arguments. Such intrinsics will have the
3605names of the arbitrary types encoded into the intrinsic function name, each
3606preceded by a period. For example, the <tt>llvm.ctpop</tt> function can take an
3607integer of any width. This leads to a family of functions such as
3608<tt>i32 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i32 @llvm.ctpop.i29(i29 %val)</tt>.
3609</p>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3610
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]3611
3612<p>To learn how to add an intrinsic function, please see the
3613<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3614</p>
3615
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3616</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3617
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3618<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3619<div class="doc_subsection">
3620 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3621</div>
3622
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3623<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3624
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3625<p>Variable argument support is defined in LLVM with the <a
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3626 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3627intrinsic functions. These functions are related to the similarly
3628named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3629
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3630<p>All of these functions operate on arguments that use a
3631target-specific value type "<tt>va_list</tt>". The LLVM assembly
3632language reference manual does not define what this type is, so all
3633transformations should be prepared to handle intrinsics with any type
3634used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3635
Chris Lattner374ab302006-05-15 17:26:46 +0000[diff] [blame]3636<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3637instruction and the variable argument handling intrinsic functions are
3638used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3639
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3640<pre>
Anton Korobeynikov5d522f32007-03-21 23:58:04 +0000[diff] [blame]3641define i32 @test(i32 %X, ...) {
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3642 ; Initialize variable argument processing
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3643 %ap = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3644 %ap2 = bitcast i8** %ap to i8*
Anton Korobeynikov5d522f32007-03-21 23:58:04 +0000[diff] [blame]3645 call void @llvm.va_start(i8* %ap2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3646
3647 ; Read a single integer argument
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3648 %tmp = va_arg i8 ** %ap, i32
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3649
3650 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3651 %aq = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3652 %aq2 = bitcast i8** %aq to i8*
Anton Korobeynikov5d522f32007-03-21 23:58:04 +0000[diff] [blame]3653 call void @llvm.va_copy(i8 *%aq2, i8* %ap2)
3654 call void @llvm.va_end(i8* %aq2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3655
3656 ; Stop processing of arguments.
Anton Korobeynikov5d522f32007-03-21 23:58:04 +0000[diff] [blame]3657 call void @llvm.va_end(i8* %ap2)
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3658 ret i32 %tmp
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3659}
Anton Korobeynikov5d522f32007-03-21 23:58:04 +0000[diff] [blame]3660
3661declare void @llvm.va_start(i8*)
3662declare void @llvm.va_copy(i8*, i8*)
3663declare void @llvm.va_end(i8*)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3664</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3665</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3666
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3667<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3668<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3669 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3670</div>
3671
3672
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3673<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3674<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3675<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3676<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3677<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3678<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3679href="#i_va_arg">va_arg</a></tt>.</p>
3680
3681<h5>Arguments:</h5>
3682
3683<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3684
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3685<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3686
3687<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3688macro available in C. In a target-dependent way, it initializes the
3689<tt>va_list</tt> element the argument points to, so that the next call to
3690<tt>va_arg</tt> will produce the first variable argument passed to the function.
3691Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3692last argument of the function, the compiler can figure that out.</p>
3693
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3694</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3695
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3696<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3697<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3698 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3699</div>
3700
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3701<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3702<h5>Syntax:</h5>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3703<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3704<h5>Overview:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3705
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3706<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3707which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3708or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3709
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3710<h5>Arguments:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3711
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3712<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3713
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3714<h5>Semantics:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3715
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3716<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3717macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3718Calls to <a href="#int_va_start"><tt>llvm.va_start</tt></a> and <a
3719 href="#int_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3720with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3721
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3722</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3723
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3724<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3725<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3726 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3727</div>
3728
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3729<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3730
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3731<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3732
3733<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3734 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3735</pre>
3736
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3737<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3738
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3739<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3740the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3741
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3742<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3743
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3744<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]3745The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3746
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3747
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3748<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3749
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3750<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3751available in C. In a target-dependent way, it copies the source
3752<tt>va_list</tt> element into the destination list. This intrinsic is necessary
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3753because the <tt><a href="#int_va_start">llvm.va_start</a></tt> intrinsic may be
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3754arbitrarily complex and require memory allocation, for example.</p>
3755
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3756</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3757
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3758<!-- ======================================================================= -->
3759<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3760 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3761</div>
3762
3763<div class="doc_text">
3764
3765<p>
3766LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3767Collection</a> requires the implementation and generation of these intrinsics.
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3768These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3769stack</a>, as well as garbage collector implementations that require <a
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3770href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3771Front-ends for type-safe garbage collected languages should generate these
3772intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3773href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3774</p>
3775</div>
3776
3777<!-- _______________________________________________________________________ -->
3778<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3779 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3780</div>
3781
3782<div class="doc_text">
3783
3784<h5>Syntax:</h5>
3785
3786<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3787 declare void @llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3788</pre>
3789
3790<h5>Overview:</h5>
3791
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]3792<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3793the code generator, and allows some metadata to be associated with it.</p>
3794
3795<h5>Arguments:</h5>
3796
3797<p>The first argument specifies the address of a stack object that contains the
3798root pointer. The second pointer (which must be either a constant or a global
3799value address) contains the meta-data to be associated with the root.</p>
3800
3801<h5>Semantics:</h5>
3802
3803<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3804location. At compile-time, the code generator generates information to allow
3805the runtime to find the pointer at GC safe points.
3806</p>
3807
3808</div>
3809
3810
3811<!-- _______________________________________________________________________ -->
3812<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3813 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3814</div>
3815
3816<div class="doc_text">
3817
3818<h5>Syntax:</h5>
3819
3820<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3821 declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3822</pre>
3823
3824<h5>Overview:</h5>
3825
3826<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3827locations, allowing garbage collector implementations that require read
3828barriers.</p>
3829
3830<h5>Arguments:</h5>
3831
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3832<p>The second argument is the address to read from, which should be an address
3833allocated from the garbage collector. The first object is a pointer to the
3834start of the referenced object, if needed by the language runtime (otherwise
3835null).</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3836
3837<h5>Semantics:</h5>
3838
3839<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3840instruction, but may be replaced with substantially more complex code by the
3841garbage collector runtime, as needed.</p>
3842
3843</div>
3844
3845
3846<!-- _______________________________________________________________________ -->
3847<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3848 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3849</div>
3850
3851<div class="doc_text">
3852
3853<h5>Syntax:</h5>
3854
3855<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3856 declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3857</pre>
3858
3859<h5>Overview:</h5>
3860
3861<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3862locations, allowing garbage collector implementations that require write
3863barriers (such as generational or reference counting collectors).</p>
3864
3865<h5>Arguments:</h5>
3866
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3867<p>The first argument is the reference to store, the second is the start of the
3868object to store it to, and the third is the address of the field of Obj to
3869store to. If the runtime does not require a pointer to the object, Obj may be
3870null.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3871
3872<h5>Semantics:</h5>
3873
3874<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3875instruction, but may be replaced with substantially more complex code by the
3876garbage collector runtime, as needed.</p>
3877
3878</div>
3879
3880
3881
3882<!-- ======================================================================= -->
3883<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3884 <a name="int_codegen">Code Generator Intrinsics</a>
3885</div>
3886
3887<div class="doc_text">
3888<p>
3889These intrinsics are provided by LLVM to expose special features that may only
3890be implemented with code generator support.
3891</p>
3892
3893</div>
3894
3895<!-- _______________________________________________________________________ -->
3896<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3897 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3898</div>
3899
3900<div class="doc_text">
3901
3902<h5>Syntax:</h5>
3903<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3904 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3905</pre>
3906
3907<h5>Overview:</h5>
3908
3909<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3910The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3911target-specific value indicating the return address of the current function
3912or one of its callers.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3913</p>
3914
3915<h5>Arguments:</h5>
3916
3917<p>
3918The argument to this intrinsic indicates which function to return the address
3919for. Zero indicates the calling function, one indicates its caller, etc. The
3920argument is <b>required</b> to be a constant integer value.
3921</p>
3922
3923<h5>Semantics:</h5>
3924
3925<p>
3926The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3927the return address of the specified call frame, or zero if it cannot be
3928identified. The value returned by this intrinsic is likely to be incorrect or 0
3929for arguments other than zero, so it should only be used for debugging purposes.
3930</p>
3931
3932<p>
3933Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3934aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3935source-language caller.
3936</p>
3937</div>
3938
3939
3940<!-- _______________________________________________________________________ -->
3941<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3942 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3943</div>
3944
3945<div class="doc_text">
3946
3947<h5>Syntax:</h5>
3948<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3949 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3950</pre>
3951
3952<h5>Overview:</h5>
3953
3954<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3955The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3956target-specific frame pointer value for the specified stack frame.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3957</p>
3958
3959<h5>Arguments:</h5>
3960
3961<p>
3962The argument to this intrinsic indicates which function to return the frame
3963pointer for. Zero indicates the calling function, one indicates its caller,
3964etc. The argument is <b>required</b> to be a constant integer value.
3965</p>
3966
3967<h5>Semantics:</h5>
3968
3969<p>
3970The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3971the frame address of the specified call frame, or zero if it cannot be
3972identified. The value returned by this intrinsic is likely to be incorrect or 0
3973for arguments other than zero, so it should only be used for debugging purposes.
3974</p>
3975
3976<p>
3977Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3978aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3979source-language caller.
3980</p>
3981</div>
3982
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3983<!-- _______________________________________________________________________ -->
3984<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3985 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3986</div>
3987
3988<div class="doc_text">
3989
3990<h5>Syntax:</h5>
3991<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]3992 declare i8 *@llvm.stacksave()
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3993</pre>
3994
3995<h5>Overview:</h5>
3996
3997<p>
3998The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]3999the function stack, for use with <a href="#int_stackrestore">
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]4000<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4001features like scoped automatic variable sized arrays in C99.
4002</p>
4003
4004<h5>Semantics:</h5>
4005
4006<p>
4007This intrinsic returns a opaque pointer value that can be passed to <a
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4008href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]4009<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4010<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4011state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4012practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4013that were allocated after the <tt>llvm.stacksave</tt> was executed.
4014</p>
4015
4016</div>
4017
4018<!-- _______________________________________________________________________ -->
4019<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4020 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]4021</div>
4022
4023<div class="doc_text">
4024
4025<h5>Syntax:</h5>
4026<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4027 declare void @llvm.stackrestore(i8 * %ptr)
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]4028</pre>
4029
4030<h5>Overview:</h5>
4031
4032<p>
4033The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4034the function stack to the state it was in when the corresponding <a
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4035href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]4036useful for implementing language features like scoped automatic variable sized
4037arrays in C99.
4038</p>
4039
4040<h5>Semantics:</h5>
4041
4042<p>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4043See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]4044</p>
4045
4046</div>
4047
4048
4049<!-- _______________________________________________________________________ -->
4050<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4051 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]4052</div>
4053
4054<div class="doc_text">
4055
4056<h5>Syntax:</h5>
4057<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4058 declare void @llvm.prefetch(i8 * &lt;address&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4059 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]4060</pre>
4061
4062<h5>Overview:</h5>
4063
4064
4065<p>
4066The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4067a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4068no
4069effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]4070characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]4071</p>
4072
4073<h5>Arguments:</h5>
4074
4075<p>
4076<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4077determining if the fetch should be for a read (0) or write (1), and
4078<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]4079locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]4080<tt>locality</tt> arguments must be constant integers.
4081</p>
4082
4083<h5>Semantics:</h5>
4084
4085<p>
4086This intrinsic does not modify the behavior of the program. In particular,
4087prefetches cannot trap and do not produce a value. On targets that support this
4088intrinsic, the prefetch can provide hints to the processor cache for better
4089performance.
4090</p>
4091
4092</div>
4093
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4094<!-- _______________________________________________________________________ -->
4095<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4096 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4097</div>
4098
4099<div class="doc_text">
4100
4101<h5>Syntax:</h5>
4102<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4103 declare void @llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4104</pre>
4105
4106<h5>Overview:</h5>
4107
4108
4109<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4110The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4111(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4112code to simulators and other tools. The method is target specific, but it is
4113expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]4114The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnerd07c3f42005-11-15 06:07:55 +0000[diff] [blame]4115after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb3e7afd2006-03-24 07:16:10 +0000[diff] [blame]4116optimizations. The intended use is to be inserted after optimizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4117correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4118</p>
4119
4120<h5>Arguments:</h5>
4121
4122<p>
4123<tt>id</tt> is a numerical id identifying the marker.
4124</p>
4125
4126<h5>Semantics:</h5>
4127
4128<p>
4129This intrinsic does not modify the behavior of the program. Backends that do not
4130support this intrinisic may ignore it.
4131</p>
4132
4133</div>
4134
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4135<!-- _______________________________________________________________________ -->
4136<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4137 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4138</div>
4139
4140<div class="doc_text">
4141
4142<h5>Syntax:</h5>
4143<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4144 declare i64 @llvm.readcyclecounter( )
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4145</pre>
4146
4147<h5>Overview:</h5>
4148
4149
4150<p>
4151The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4152counter register (or similar low latency, high accuracy clocks) on those targets
4153that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4154As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4155should only be used for small timings.
4156</p>
4157
4158<h5>Semantics:</h5>
4159
4160<p>
4161When directly supported, reading the cycle counter should not modify any memory.
4162Implementations are allowed to either return a application specific value or a
4163system wide value. On backends without support, this is lowered to a constant 0.
4164</p>
4165
4166</div>
4167
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4168<!-- ======================================================================= -->
4169<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4170 <a name="int_libc">Standard C Library Intrinsics</a>
4171</div>
4172
4173<div class="doc_text">
4174<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4175LLVM provides intrinsics for a few important standard C library functions.
4176These intrinsics allow source-language front-ends to pass information about the
4177alignment of the pointer arguments to the code generator, providing opportunity
4178for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4179</p>
4180
4181</div>
4182
4183<!-- _______________________________________________________________________ -->
4184<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4185 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4186</div>
4187
4188<div class="doc_text">
4189
4190<h5>Syntax:</h5>
4191<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4192 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4193 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4194 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4195 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4196</pre>
4197
4198<h5>Overview:</h5>
4199
4200<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4201The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4202location to the destination location.
4203</p>
4204
4205<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4206Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4207intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4208</p>
4209
4210<h5>Arguments:</h5>
4211
4212<p>
4213The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4214the source. The third argument is an integer argument
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4215specifying the number of bytes to copy, and the fourth argument is the alignment
4216of the source and destination locations.
4217</p>
4218
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4219<p>
4220If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattnerf0afc2c2006-03-04 00:02:10 +0000[diff] [blame]4221the caller guarantees that both the source and destination pointers are aligned
4222to that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4223</p>
4224
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4225<h5>Semantics:</h5>
4226
4227<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4228The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4229location to the destination location, which are not allowed to overlap. It
4230copies "len" bytes of memory over. If the argument is known to be aligned to
4231some boundary, this can be specified as the fourth argument, otherwise it should
4232be set to 0 or 1.
4233</p>
4234</div>
4235
4236
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4237<!-- _______________________________________________________________________ -->
4238<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4239 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4240</div>
4241
4242<div class="doc_text">
4243
4244<h5>Syntax:</h5>
4245<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4246 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4247 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4248 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4249 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4250</pre>
4251
4252<h5>Overview:</h5>
4253
4254<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4255The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4256location to the destination location. It is similar to the
4257'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4258</p>
4259
4260<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4261Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4262intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4263</p>
4264
4265<h5>Arguments:</h5>
4266
4267<p>
4268The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4269the source. The third argument is an integer argument
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4270specifying the number of bytes to copy, and the fourth argument is the alignment
4271of the source and destination locations.
4272</p>
4273
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4274<p>
4275If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattnerf0afc2c2006-03-04 00:02:10 +0000[diff] [blame]4276the caller guarantees that the source and destination pointers are aligned to
4277that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4278</p>
4279
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4280<h5>Semantics:</h5>
4281
4282<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4283The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4284location to the destination location, which may overlap. It
4285copies "len" bytes of memory over. If the argument is known to be aligned to
4286some boundary, this can be specified as the fourth argument, otherwise it should
4287be set to 0 or 1.
4288</p>
4289</div>
4290
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4291
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4292<!-- _______________________________________________________________________ -->
4293<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4294 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4295</div>
4296
4297<div class="doc_text">
4298
4299<h5>Syntax:</h5>
4300<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4301 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4302 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4303 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4304 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4305</pre>
4306
4307<h5>Overview:</h5>
4308
4309<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4310The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4311byte value.
4312</p>
4313
4314<p>
4315Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4316does not return a value, and takes an extra alignment argument.
4317</p>
4318
4319<h5>Arguments:</h5>
4320
4321<p>
4322The first argument is a pointer to the destination to fill, the second is the
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4323byte value to fill it with, the third argument is an integer
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4324argument specifying the number of bytes to fill, and the fourth argument is the
4325known alignment of destination location.
4326</p>
4327
4328<p>
4329If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattnerf0afc2c2006-03-04 00:02:10 +0000[diff] [blame]4330the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4331</p>
4332
4333<h5>Semantics:</h5>
4334
4335<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4336The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4337the
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4338destination location. If the argument is known to be aligned to some boundary,
4339this can be specified as the fourth argument, otherwise it should be set to 0 or
43401.
4341</p>
4342</div>
4343
4344
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4345<!-- _______________________________________________________________________ -->
4346<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4347 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4348</div>
4349
4350<div class="doc_text">
4351
4352<h5>Syntax:</h5>
4353<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4354 declare float @llvm.sqrt.f32(float %Val)
4355 declare double @llvm.sqrt.f64(double %Val)
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4356</pre>
4357
4358<h5>Overview:</h5>
4359
4360<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4361The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4362returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4363<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4364negative numbers (which allows for better optimization).
4365</p>
4366
4367<h5>Arguments:</h5>
4368
4369<p>
4370The argument and return value are floating point numbers of the same type.
4371</p>
4372
4373<h5>Semantics:</h5>
4374
4375<p>
4376This function returns the sqrt of the specified operand if it is a positive
4377floating point number.
4378</p>
4379</div>
4380
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4381<!-- _______________________________________________________________________ -->
4382<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4383 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4384</div>
4385
4386<div class="doc_text">
4387
4388<h5>Syntax:</h5>
4389<pre>
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4390 declare float @llvm.powi.f32(float %Val, i32 %power)
4391 declare double @llvm.powi.f64(double %Val, i32 %power)
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4392</pre>
4393
4394<h5>Overview:</h5>
4395
4396<p>
4397The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4398specified (positive or negative) power. The order of evaluation of
4399multiplications is not defined.
4400</p>
4401
4402<h5>Arguments:</h5>
4403
4404<p>
4405The second argument is an integer power, and the first is a value to raise to
4406that power.
4407</p>
4408
4409<h5>Semantics:</h5>
4410
4411<p>
4412This function returns the first value raised to the second power with an
4413unspecified sequence of rounding operations.</p>
4414</div>
4415
4416
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4417<!-- ======================================================================= -->
4418<div class="doc_subsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4419 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4420</div>
4421
4422<div class="doc_text">
4423<p>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4424LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4425These allow efficient code generation for some algorithms.
4426</p>
4427
4428</div>
4429
4430<!-- _______________________________________________________________________ -->
4431<div class="doc_subsubsection">
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4432 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4433</div>
4434
4435<div class="doc_text">
4436
4437<h5>Syntax:</h5>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4438<p>This is an overloaded intrinsic function. You can use bswap on any integer
4439type that is an even number of bytes (i.e. BitWidth % 16 == 0). Note the suffix
4440that includes the type for the result and the operand.
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4441<pre>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4442 declare i16 @llvm.bswap.i16.i16(i16 &lt;id&gt;)
4443 declare i32 @llvm.bswap.i32.i32(i32 &lt;id&gt;)
Reid Spencer543ab1d2007-04-02 00:19:52 +0000[diff] [blame]4444 declare i64 @llvm.bswap.i64.i64(i64 &lt;id&gt;)
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4445</pre>
4446
4447<h5>Overview:</h5>
4448
4449<p>
Reid Spencer338ea092007-04-02 02:25:19 +0000[diff] [blame]4450The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4451values with an even number of bytes (positive multiple of 16 bits). These are
4452useful for performing operations on data that is not in the target's native
4453byte order.
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4454</p>
4455
4456<h5>Semantics:</h5>
4457
4458<p>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4459The <tt>llvm.bswap.16.i16</tt> intrinsic returns an i16 value that has the high
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4460and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4461intrinsic returns an i32 value that has the four bytes of the input i32
4462swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4463i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48.i48</tt>,
4464<tt>llvm.bswap.i64.i64</tt> and other intrinsics extend this concept to
4465additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4466</p>
4467
4468</div>
4469
4470<!-- _______________________________________________________________________ -->
4471<div class="doc_subsubsection">
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4472 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4473</div>
4474
4475<div class="doc_text">
4476
4477<h5>Syntax:</h5>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4478<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4479width. Not all targets support all bit widths however.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4480<pre>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4481 declare i32 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4482 declare i32 @llvm.ctpop.i16(i16 &lt;src&gt;)
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4483 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4484 declare i32 @llvm.ctpop.i64(i64 &lt;src&gt;)
4485 declare i32 @llvm.ctpop.i256(i256 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4486</pre>
4487
4488<h5>Overview:</h5>
4489
4490<p>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4491The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4492value.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4493</p>
4494
4495<h5>Arguments:</h5>
4496
4497<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4498The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4499integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4500</p>
4501
4502<h5>Semantics:</h5>
4503
4504<p>
4505The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4506</p>
4507</div>
4508
4509<!-- _______________________________________________________________________ -->
4510<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4511 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4512</div>
4513
4514<div class="doc_text">
4515
4516<h5>Syntax:</h5>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4517<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4518integer bit width. Not all targets support all bit widths however.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4519<pre>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4520 declare i32 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4521 declare i32 @llvm.ctlz.i16(i16 &lt;src&gt;)
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4522 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4523 declare i32 @llvm.ctlz.i64(i64 &lt;src&gt;)
4524 declare i32 @llvm.ctlz.i256(i256 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4525</pre>
4526
4527<h5>Overview:</h5>
4528
4529<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4530The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4531leading zeros in a variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4532</p>
4533
4534<h5>Arguments:</h5>
4535
4536<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4537The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4538integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4539</p>
4540
4541<h5>Semantics:</h5>
4542
4543<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4544The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4545in a variable. If the src == 0 then the result is the size in bits of the type
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4546of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4547</p>
4548</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4549
4550
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4551
4552<!-- _______________________________________________________________________ -->
4553<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4554 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4555</div>
4556
4557<div class="doc_text">
4558
4559<h5>Syntax:</h5>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4560<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4561integer bit width. Not all targets support all bit widths however.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4562<pre>
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4563 declare i32 @llvm.cttz.i8 (i8 &lt;src&gt;)
4564 declare i32 @llvm.cttz.i16(i16 &lt;src&gt;)
Anton Korobeynikovec43a062007-03-22 00:02:17 +0000[diff] [blame]4565 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Reid Spencer409e28f2007-04-01 08:04:23 +0000[diff] [blame]4566 declare i32 @llvm.cttz.i64(i64 &lt;src&gt;)
4567 declare i32 @llvm.cttz.i256(i256 &lt;src&gt;)
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4568</pre>
4569
4570<h5>Overview:</h5>
4571
4572<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4573The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4574trailing zeros.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4575</p>
4576
4577<h5>Arguments:</h5>
4578
4579<p>
4580The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4581integer type. The return type must match the argument type.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4582</p>
4583
4584<h5>Semantics:</h5>
4585
4586<p>
4587The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4588in a variable. If the src == 0 then the result is the size in bits of the type
4589of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4590</p>
4591</div>
4592
Reid Spencer497d93e2007-04-01 08:27:01 +0000[diff] [blame]4593<!-- _______________________________________________________________________ -->
4594<div class="doc_subsubsection">
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4595 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4596</div>
4597
4598<div class="doc_text">
4599
4600<h5>Syntax:</h5>
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4601<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4602on any integer bit width.
4603<pre>
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4604 declare i17 @llvm.part.select.i17.i17 (i17 %val, i32 %loBit, i32 %hiBit)
4605 declare i29 @llvm.part.select.i29.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4606</pre>
4607
4608<h5>Overview:</h5>
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4609<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4610range of bits from an integer value and returns them in the same bit width as
4611the original value.</p>
4612
4613<h5>Arguments:</h5>
4614<p>The first argument, <tt>%val</tt> and the result may be integer types of
4615any bit width but they must have the same bit width. The second and third
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4616arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4617
4618<h5>Semantics:</h5>
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4619<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4620of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
4621<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
4622operates in forward mode.</p>
4623<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
4624right by <tt>%loBit</tt> bits and then ANDing it with a mask with
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4625only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
4626<ol>
4627 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
4628 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
4629 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
4630 to determine the number of bits to retain.</li>
4631 <li>A mask of the retained bits is created by shifting a -1 value.</li>
4632 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
4633</ol>
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4634<p>In reverse mode, a similar computation is made except that:</p>
4635<ol>
4636 <li>The bits selected wrap around to include both the highest and lowest bits.
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4637 For example, part.select(i16 X, 4, 7) selects bits from X with a mask of
4638 0x00F0 (forwards case) while part.select(i16 X, 8, 3) selects bits from X
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4639 with a mask of 0xFF0F.</li>
4640 <li>The bits returned in the reverse case are reversed. So, if X has the value
Reid Spencerbeacf662007-04-10 02:51:31 +0000[diff] [blame]4641 0x6ACF and we apply part.select(i16 X, 8, 3) to it, we get back the value
Reid Spencera3e435f2007-04-04 02:42:35 +0000[diff] [blame]4642 0x0A6F.</li>
4643</ol>
Reid Spencera13ba7d2007-04-01 19:00:37 +0000[diff] [blame]4644</div>
4645
Reid Spencerf86037f2007-04-11 23:23:49 +0000[diff] [blame]4646<div class="doc_subsubsection">
4647 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
4648</div>
4649
4650<div class="doc_text">
4651
4652<h5>Syntax:</h5>
4653<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
4654on any integer bit width.
4655<pre>
4656 declare i17 @llvm.part.set.i17.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
4657 declare i29 @llvm.part.set.i29.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
4658</pre>
4659
4660<h5>Overview:</h5>
4661<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
4662of bits in an integer value with another integer value. It returns the integer
4663with the replaced bits.</p>
4664
4665<h5>Arguments:</h5>
4666<p>The first argument, <tt>%val</tt> and the result may be integer types of
4667any bit width but they must have the same bit width. <tt>%val</tt> is the value
4668whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
4669integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
4670type since they specify only a bit index.</p>
4671
4672<h5>Semantics:</h5>
4673<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
4674of operation: forwards and reverse. If <tt>%lo</tt> is greater than
4675<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
4676operates in forward mode.</p>
4677<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
4678truncating it down to the size of the replacement area or zero extending it
4679up to that size.</p>
4680<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
4681are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
4682in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
4683to the <tt>%hi</tt>th bit.
4684<p>In reverse mode, a similar computation is made except that the bits replaced
4685wrap around to include both the highest and lowest bits. For example, if a
468616 bit value is being replaced then <tt>%lo=8</tt> and <tt>%hi=4</tt> would
Reid Spencer065cc7f2007-04-11 23:46:06 +0000[diff] [blame]4687cause these bits to be set: <tt>0xFF1F</tt>.</p>
Reid Spencerf86037f2007-04-11 23:23:49 +0000[diff] [blame]4688<h5>Examples:</h5>
4689<pre>
Reid Spencerf0dbf642007-04-12 01:03:03 +0000[diff] [blame]4690 llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
4691 llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0x0060
4692 llvm.part.set(0xFFFF, 0, 8, 3) -&gt; 0x00F0
4693 llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
Reid Spencerc8910842007-04-11 23:49:50 +0000[diff] [blame]4694</pre>
Reid Spencerf86037f2007-04-11 23:23:49 +0000[diff] [blame]4695</div>
4696
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4697<!-- ======================================================================= -->
4698<div class="doc_subsection">
4699 <a name="int_debugger">Debugger Intrinsics</a>
4700</div>
4701
4702<div class="doc_text">
4703<p>
4704The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4705are described in the <a
4706href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4707Debugging</a> document.
4708</p>
4709</div>
4710
4711
Jim Laskeydd4ef1b2007-03-14 19:31:19 +0000[diff] [blame]4712<!-- ======================================================================= -->
4713<div class="doc_subsection">
4714 <a name="int_eh">Exception Handling Intrinsics</a>
4715</div>
4716
4717<div class="doc_text">
4718<p> The LLVM exception handling intrinsics (which all start with
4719<tt>llvm.eh.</tt> prefix), are described in the <a
4720href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
4721Handling</a> document. </p>
4722</div>
4723
4724
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4725<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4726<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4727<address>
4728 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4729 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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4731 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4732
4733 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]4734 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4735 Last modified: $Date$
4736</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]4737</body>
4738</html>