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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / fd58e6e2ecebe92804869586d65b27085110f336 / . / 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.">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]10 <link rel="stylesheet" href="llvm.css" type="text/css">
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>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]29 </ol>
30 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]31 <li><a href="#typesystem">Type System</a>
32 <ol>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]33 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]34 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]35 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]36 </ol>
37 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]38 <li><a href="#t_derived">Derived Types</a>
39 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]40 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]41 <li><a href="#t_function">Function Type</a></li>
42 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]43 <li><a href="#t_struct">Structure Type</a></li>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]44 <li><a href="#t_pstruct">Packed Structure Type</a></li>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]45 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]46 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]47 </ol>
48 </li>
49 </ol>
50 </li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]51 <li><a href="#constants">Constants</a>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]52 <ol>
53 <li><a href="#simpleconstants">Simple Constants</a>
54 <li><a href="#aggregateconstants">Aggregate Constants</a>
55 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
56 <li><a href="#undefvalues">Undefined Values</a>
57 <li><a href="#constantexprs">Constant Expressions</a>
58 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]59 </li>
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]60 <li><a href="#othervalues">Other Values</a>
61 <ol>
62 <li><a href="#inlineasm">Inline Assembler Expressions</a>
63 </ol>
64 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]65 <li><a href="#instref">Instruction Reference</a>
66 <ol>
67 <li><a href="#terminators">Terminator Instructions</a>
68 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]69 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
70 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]71 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
72 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]73 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]74 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]75 </ol>
76 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]77 <li><a href="#binaryops">Binary Operations</a>
78 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]79 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
80 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
81 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]82 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
83 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
84 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]85 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
86 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
87 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]88 </ol>
89 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]90 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
91 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]92 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]93 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]94 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
95 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]96 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
97 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]98 </ol>
99 </li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]100 <li><a href="#vectorops">Vector Operations</a>
101 <ol>
102 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
103 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
104 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]105 </ol>
106 </li>
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]107 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]108 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]109 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
110 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
111 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]112 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
113 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
114 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]115 </ol>
116 </li>
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]117 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]118 <ol>
119 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
120 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
121 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
122 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
123 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]124 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
125 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
126 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
127 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]128 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
129 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]130 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]131 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]132 <li><a href="#otherops">Other Operations</a>
133 <ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]134 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
135 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]136 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]137 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]138 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]139 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]140 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]141 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]142 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]143 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]144 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]145 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]146 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
147 <ol>
148 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
149 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
150 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
151 </ol>
152 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]153 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
154 <ol>
155 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
156 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
157 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
158 </ol>
159 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]160 <li><a href="#int_codegen">Code Generator Intrinsics</a>
161 <ol>
162 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
163 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]164 <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
165 <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]166 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]167 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]168 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]169 </ol>
170 </li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]171 <li><a href="#int_libc">Standard C Library Intrinsics</a>
172 <ol>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]173 <li><a href="#i_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
174 <li><a href="#i_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
175 <li><a href="#i_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]176 <li><a href="#i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]177 <li><a href="#i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]178 </ol>
179 </li>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]180 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]181 <ol>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]182 <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]183 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
184 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
185 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]186 </ol>
187 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]188 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]189 </ol>
190 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]191</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]192
193<div class="doc_author">
194 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
195 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]196</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]197
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]198<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]199<div class="doc_section"> <a name="abstract">Abstract </a></div>
200<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]201
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]202<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]203<p>This document is a reference manual for the LLVM assembly language.
204LLVM is an SSA based representation that provides type safety,
205low-level operations, flexibility, and the capability of representing
206'all' high-level languages cleanly. It is the common code
207representation used throughout all phases of the LLVM compilation
208strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]209</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]210
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]211<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]212<div class="doc_section"> <a name="introduction">Introduction</a> </div>
213<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]214
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]215<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]216
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]217<p>The LLVM code representation is designed to be used in three
218different forms: as an in-memory compiler IR, as an on-disk bytecode
219representation (suitable for fast loading by a Just-In-Time compiler),
220and as a human readable assembly language representation. This allows
221LLVM to provide a powerful intermediate representation for efficient
222compiler transformations and analysis, while providing a natural means
223to debug and visualize the transformations. The three different forms
224of LLVM are all equivalent. This document describes the human readable
225representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]226
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]227<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]228while being expressive, typed, and extensible at the same time. It
229aims to be a "universal IR" of sorts, by being at a low enough level
230that high-level ideas may be cleanly mapped to it (similar to how
231microprocessors are "universal IR's", allowing many source languages to
232be mapped to them). By providing type information, LLVM can be used as
233the target of optimizations: for example, through pointer analysis, it
234can be proven that a C automatic variable is never accessed outside of
235the current function... allowing it to be promoted to a simple SSA
236value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]237
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]238</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]239
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]240<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]241<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]242
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]243<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]244
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]245<p>It is important to note that this document describes 'well formed'
246LLVM assembly language. There is a difference between what the parser
247accepts and what is considered 'well formed'. For example, the
248following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]249
250<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]251 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]252</pre>
253
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]254<p>...because the definition of <tt>%x</tt> does not dominate all of
255its uses. The LLVM infrastructure provides a verification pass that may
256be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]257automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]258the optimizer before it outputs bytecode. The violations pointed out
259by the verifier pass indicate bugs in transformation passes or input to
260the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]261
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]262<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]263
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]264<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]265<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]266<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]267
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]268<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]269
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]270<p>LLVM uses three different forms of identifiers, for different
271purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]272
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]273<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]274 <li>Named values are represented as a string of characters with a '%' prefix.
275 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
276 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
277 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]278 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]279 in a name.</li>
280
281 <li>Unnamed values are represented as an unsigned numeric value with a '%'
282 prefix. For example, %12, %2, %44.</li>
283
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]284 <li>Constants, which are described in a <a href="#constants">section about
285 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]286</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]287
288<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
289don't need to worry about name clashes with reserved words, and the set of
290reserved words may be expanded in the future without penalty. Additionally,
291unnamed identifiers allow a compiler to quickly come up with a temporary
292variable without having to avoid symbol table conflicts.</p>
293
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]294<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]295languages. There are keywords for different opcodes
296('<tt><a href="#i_add">add</a></tt>',
297 '<tt><a href="#i_bitcast">bitcast</a></tt>',
298 '<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]299href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]300and others. These reserved words cannot conflict with variable names, because
301none of them start with a '%' character.</p>
302
303<p>Here is an example of LLVM code to multiply the integer variable
304'<tt>%X</tt>' by 8:</p>
305
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]306<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]307
308<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]309 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]310</pre>
311
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]312<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]313
314<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]315 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]316</pre>
317
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]318<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]319
320<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]321 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
322 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
323 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]324</pre>
325
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]326<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
327important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]328
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]329<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]330
331 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
332 line.</li>
333
334 <li>Unnamed temporaries are created when the result of a computation is not
335 assigned to a named value.</li>
336
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]337 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]338
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]339</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]340
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]341<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]342demonstrating instructions, we will follow an instruction with a comment that
343defines the type and name of value produced. Comments are shown in italic
344text.</p>
345
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]346</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]347
348<!-- *********************************************************************** -->
349<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
350<!-- *********************************************************************** -->
351
352<!-- ======================================================================= -->
353<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
354</div>
355
356<div class="doc_text">
357
358<p>LLVM programs are composed of "Module"s, each of which is a
359translation unit of the input programs. Each module consists of
360functions, global variables, and symbol table entries. Modules may be
361combined together with the LLVM linker, which merges function (and
362global variable) definitions, resolves forward declarations, and merges
363symbol table entries. Here is an example of the "hello world" module:</p>
364
365<pre><i>; Declare the string constant as a global constant...</i>
366<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]367 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]368
369<i>; External declaration of the puts function</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]370<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]371
Chris Lattner81c01f02006-06-13 03:05:47 +0000[diff] [blame]372<i>; Global variable / Function body section separator</i>
373implementation
374
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]375<i>; Definition of main function</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]376define i32 %main() { <i>; i32()* </i>
377 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]378 %cast210 = <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]379 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]380
381 <i>; Call puts function to write out the string to stdout...</i>
382 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]383 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]384 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]385 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]386
387<p>This example is made up of a <a href="#globalvars">global variable</a>
388named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
389function, and a <a href="#functionstructure">function definition</a>
390for "<tt>main</tt>".</p>
391
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]392<p>In general, a module is made up of a list of global values,
393where both functions and global variables are global values. Global values are
394represented by a pointer to a memory location (in this case, a pointer to an
395array of char, and a pointer to a function), and have one of the following <a
396href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]397
Chris Lattner81c01f02006-06-13 03:05:47 +0000[diff] [blame]398<p>Due to a limitation in the current LLVM assembly parser (it is limited by
399one-token lookahead), modules are split into two pieces by the "implementation"
400keyword. Global variable prototypes and definitions must occur before the
401keyword, and function definitions must occur after it. Function prototypes may
402occur either before or after it. In the future, the implementation keyword may
403become a noop, if the parser gets smarter.</p>
404
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsection">
409 <a name="linkage">Linkage Types</a>
410</div>
411
412<div class="doc_text">
413
414<p>
415All Global Variables and Functions have one of the following types of linkage:
416</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]417
418<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]419
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]420 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]421
422 <dd>Global values with internal linkage are only directly accessible by
423 objects in the current module. In particular, linking code into a module with
424 an internal global value may cause the internal to be renamed as necessary to
425 avoid collisions. Because the symbol is internal to the module, all
426 references can be updated. This corresponds to the notion of the
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]427 '<tt>static</tt>' keyword in C.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]428 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]429
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]430 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]431
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]432 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
433 the same name when linkage occurs. This is typically used to implement
434 inline functions, templates, or other code which must be generated in each
435 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
436 allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]437 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]438
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]439 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]440
441 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
442 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]443 used for globals that may be emitted in multiple translation units, but that
444 are not guaranteed to be emitted into every translation unit that uses them.
445 One example of this are common globals in C, such as "<tt>int X;</tt>" at
446 global scope.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]447 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]448
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]449 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]450
451 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
452 pointer to array type. When two global variables with appending linkage are
453 linked together, the two global arrays are appended together. This is the
454 LLVM, typesafe, equivalent of having the system linker append together
455 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]456 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]457
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]458 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
459 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
460 until linked, if not linked, the symbol becomes null instead of being an
461 undefined reference.
462 </dd>
463</dl>
464
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]465 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]466
467 <dd>If none of the above identifiers are used, the global is externally
468 visible, meaning that it participates in linkage and can be used to resolve
469 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]470 </dd>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]471
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]472 <p>
473 The next two types of linkage are targeted for Microsoft Windows platform
474 only. They are designed to support importing (exporting) symbols from (to)
475 DLLs.
476 </p>
477
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]478 <dl>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]479 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
480
481 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
482 or variable via a global pointer to a pointer that is set up by the DLL
483 exporting the symbol. On Microsoft Windows targets, the pointer name is
484 formed by combining <code>_imp__</code> and the function or variable name.
485 </dd>
486
487 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
488
489 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
490 pointer to a pointer in a DLL, so that it can be referenced with the
491 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
492 name is formed by combining <code>_imp__</code> and the function or variable
493 name.
494 </dd>
495
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]496</dl>
497
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]498<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]499variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
500variable and was linked with this one, one of the two would be renamed,
501preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
502external (i.e., lacking any linkage declarations), they are accessible
Reid Spencerac8d2762007-01-05 00:59:10 +0000[diff] [blame]503outside of the current module.</p>
504<p>It is illegal for a function <i>declaration</i>
505to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]506or <tt>extern_weak</tt>.</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]507
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]508</div>
509
510<!-- ======================================================================= -->
511<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]512 <a name="callingconv">Calling Conventions</a>
513</div>
514
515<div class="doc_text">
516
517<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
518and <a href="#i_invoke">invokes</a> can all have an optional calling convention
519specified for the call. The calling convention of any pair of dynamic
520caller/callee must match, or the behavior of the program is undefined. The
521following calling conventions are supported by LLVM, and more may be added in
522the future:</p>
523
524<dl>
525 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
526
527 <dd>This calling convention (the default if no other calling convention is
528 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]529 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencerc28d2bc2006-12-31 21:30:18 +0000[diff] [blame]530 prototype and implemented declaration of the function (as does normal C).
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]531 </dd>
532
Chris Lattner5710ce92006-05-19 21:15:36 +0000[diff] [blame]533 <dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
534
535 <dd>This calling convention matches the target C calling conventions, except
536 that functions with this convention are required to take a pointer as their
537 first argument, and the return type of the function must be void. This is
538 used for C functions that return aggregates by-value. In this case, the
539 function has been transformed to take a pointer to the struct as the first
540 argument to the function. For targets where the ABI specifies specific
541 behavior for structure-return calls, the calling convention can be used to
542 distinguish between struct return functions and other functions that take a
543 pointer to a struct as the first argument.
544 </dd>
545
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]546 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
547
548 <dd>This calling convention attempts to make calls as fast as possible
549 (e.g. by passing things in registers). This calling convention allows the
550 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]551 without having to conform to an externally specified ABI. Implementations of
552 this convention should allow arbitrary tail call optimization to be supported.
553 This calling convention does not support varargs and requires the prototype of
554 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]555 </dd>
556
557 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
558
559 <dd>This calling convention attempts to make code in the caller as efficient
560 as possible under the assumption that the call is not commonly executed. As
561 such, these calls often preserve all registers so that the call does not break
562 any live ranges in the caller side. This calling convention does not support
563 varargs and requires the prototype of all callees to exactly match the
564 prototype of the function definition.
565 </dd>
566
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]567 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]568
569 <dd>Any calling convention may be specified by number, allowing
570 target-specific calling conventions to be used. Target specific calling
571 conventions start at 64.
572 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]573</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]574
575<p>More calling conventions can be added/defined on an as-needed basis, to
576support pascal conventions or any other well-known target-independent
577convention.</p>
578
579</div>
580
581<!-- ======================================================================= -->
582<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]583 <a name="globalvars">Global Variables</a>
584</div>
585
586<div class="doc_text">
587
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]588<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]589instead of run-time. Global variables may optionally be initialized, may have
590an explicit section to be placed in, and may
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]591have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]592variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]593contents of the variable will <b>never</b> be modified (enabling better
594optimization, allowing the global data to be placed in the read-only section of
595an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]596cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]597
598<p>
599LLVM explicitly allows <em>declarations</em> of global variables to be marked
600constant, even if the final definition of the global is not. This capability
601can be used to enable slightly better optimization of the program, but requires
602the language definition to guarantee that optimizations based on the
603'constantness' are valid for the translation units that do not include the
604definition.
605</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]606
607<p>As SSA values, global variables define pointer values that are in
608scope (i.e. they dominate) all basic blocks in the program. Global
609variables always define a pointer to their "content" type because they
610describe a region of memory, and all memory objects in LLVM are
611accessed through pointers.</p>
612
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]613<p>LLVM allows an explicit section to be specified for globals. If the target
614supports it, it will emit globals to the section specified.</p>
615
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]616<p>An explicit alignment may be specified for a global. If not present, or if
617the alignment is set to zero, the alignment of the global is set by the target
618to whatever it feels convenient. If an explicit alignment is specified, the
619global is forced to have at least that much alignment. All alignments must be
620a power of 2.</p>
621
Chris Lattner68027ea2007-01-14 00:27:09 +0000[diff] [blame]622<p>For example, the following defines a global with an initializer, section,
623 and alignment:</p>
624
625<pre>
626 %G = constant float 1.0, section "foo", align 4
627</pre>
628
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]629</div>
630
631
632<!-- ======================================================================= -->
633<div class="doc_subsection">
634 <a name="functionstructure">Functions</a>
635</div>
636
637<div class="doc_text">
638
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]639<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
640an optional <a href="#linkage">linkage type</a>, an optional
641<a href="#callingconv">calling convention</a>, a return type, an optional
642<a href="#paramattrs">parameter attribute</a> for the return type, a function
643name, a (possibly empty) argument list (each with optional
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]644<a href="#paramattrs">parameter attributes</a>), an optional section, an
645optional alignment, an opening curly brace, a list of basic blocks, and a
646closing curly brace. LLVM function declarations
647consist of the "<tt>declare</tt>" keyword, an optional <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]648 href="#callingconv">calling convention</a>, a return type, an optional
649<a href="#paramattrs">parameter attribute</a> for the return type, a function
650name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]651
652<p>A function definition contains a list of basic blocks, forming the CFG for
653the function. Each basic block may optionally start with a label (giving the
654basic block a symbol table entry), contains a list of instructions, and ends
655with a <a href="#terminators">terminator</a> instruction (such as a branch or
656function return).</p>
657
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]658<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]659executed on entrance to the function, and it is not allowed to have predecessor
660basic blocks (i.e. there can not be any branches to the entry block of a
661function). Because the block can have no predecessors, it also cannot have any
662<a href="#i_phi">PHI nodes</a>.</p>
663
664<p>LLVM functions are identified by their name and type signature. Hence, two
665functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]666considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]667appropriately.</p>
668
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]669<p>LLVM allows an explicit section to be specified for functions. If the target
670supports it, it will emit functions to the section specified.</p>
671
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]672<p>An explicit alignment may be specified for a function. If not present, or if
673the alignment is set to zero, the alignment of the function is set by the target
674to whatever it feels convenient. If an explicit alignment is specified, the
675function is forced to have at least that much alignment. All alignments must be
676a power of 2.</p>
677
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]678</div>
679
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]680<!-- ======================================================================= -->
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]681<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
682<div class="doc_text">
683 <p>The return type and each parameter of a function type may have a set of
684 <i>parameter attributes</i> associated with them. Parameter attributes are
685 used to communicate additional information about the result or parameters of
686 a function. Parameter attributes are considered to be part of the function
687 type so two functions types that differ only by the parameter attributes
688 are different function types.</p>
689
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]690 <p>Parameter attributes are simple keywords that follow the type specified. If
691 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]692 example:</p><pre>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]693 %someFunc = i16 (i8 sext %someParam) zext
694 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]695 <p>Note that the two function types above are unique because the parameter has
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]696 a different attribute (sext in the first one, zext in the second). Also note
697 that the attribute for the function result (zext) comes immediately after the
698 argument list.</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]699
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]700 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]701 <dl>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]702 <dt><tt>zext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]703 <dd>This indicates that the parameter should be zero extended just before
704 a call to this function.</dd>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]705 <dt><tt>sext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]706 <dd>This indicates that the parameter should be sign extended just before
707 a call to this function.</dd>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]708 </dl>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]709
710 <p>The current motivation for parameter attributes is to enable the sign and
711 zero extend information necessary for the C calling convention to be passed
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]712 from the front end to LLVM. The <tt>zext</tt> and <tt>sext</tt> attributes
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]713 are used by the code generator to perform the required extension. However,
714 parameter attributes are an orthogonal feature to calling conventions and
715 may be used for other purposes in the future.</p>
716</div>
717
718<!-- ======================================================================= -->
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]719<div class="doc_subsection">
Chris Lattner1eeeb0c2006-04-08 04:40:53 +0000[diff] [blame]720 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]721</div>
722
723<div class="doc_text">
724<p>
725Modules may contain "module-level inline asm" blocks, which corresponds to the
726GCC "file scope inline asm" blocks. These blocks are internally concatenated by
727LLVM and treated as a single unit, but may be separated in the .ll file if
728desired. The syntax is very simple:
729</p>
730
731<div class="doc_code"><pre>
Chris Lattner52599e12006-01-24 00:37:20 +0000[diff] [blame]732 module asm "inline asm code goes here"
733 module asm "more can go here"
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]734</pre></div>
735
736<p>The strings can contain any character by escaping non-printable characters.
737 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
738 for the number.
739</p>
740
741<p>
742 The inline asm code is simply printed to the machine code .s file when
743 assembly code is generated.
744</p>
745</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]746
747
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]748<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]749<div class="doc_section"> <a name="typesystem">Type System</a> </div>
750<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]751
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]752<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]753
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]754<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]755intermediate representation. Being typed enables a number of
756optimizations to be performed on the IR directly, without having to do
757extra analyses on the side before the transformation. A strong type
758system makes it easier to read the generated code and enables novel
759analyses and transformations that are not feasible to perform on normal
760three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]761
762</div>
763
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]764<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]765<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]766<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]767<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]768system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]769
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]770<table class="layout">
771 <tr class="layout">
772 <td class="left">
773 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]774 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]775 <tr><th>Type</th><th>Description</th></tr>
776 <tr><td><tt>void</tt></td><td>No value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]777 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
778 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]779 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]780 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]781 </tbody>
782 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]783 </td>
784 <td class="right">
785 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]786 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]787 <tr><th>Type</th><th>Description</th></tr>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]788 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]789 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
790 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]791 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]792 </tbody>
793 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]794 </td>
795 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]796</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]797</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]798
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]799<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]800<div class="doc_subsubsection"> <a name="t_classifications">Type
801Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]802<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]803<p>These different primitive types fall into a few useful
804classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]805
806<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]807 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]808 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]809 <tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]810 <td><a name="t_integer">integer</a></td>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]811 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]812 </tr>
813 <tr>
814 <td><a name="t_floating">floating point</a></td>
815 <td><tt>float, double</tt></td>
816 </tr>
817 <tr>
818 <td><a name="t_firstclass">first class</a></td>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]819 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]820 <a href="#t_pointer">pointer</a>,<a href="#t_packed">packed</a></tt>
821 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]822 </tr>
823 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]824</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]825
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]826<p>The <a href="#t_firstclass">first class</a> types are perhaps the
827most important. Values of these types are the only ones which can be
828produced by instructions, passed as arguments, or used as operands to
829instructions. This means that all structures and arrays must be
830manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]831</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]832
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]833<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]834<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]835
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]836<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]837
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]838<p>The real power in LLVM comes from the derived types in the system.
839This is what allows a programmer to represent arrays, functions,
840pointers, and other useful types. Note that these derived types may be
841recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]842
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]843</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]844
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]845<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]846<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]847
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]848<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]849
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]850<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]851
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]852<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]853sequentially in memory. The array type requires a size (number of
854elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]855
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]856<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]857
858<pre>
859 [&lt;# elements&gt; x &lt;elementtype&gt;]
860</pre>
861
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]862<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]863be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]864
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]865<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]866<table class="layout">
867 <tr class="layout">
868 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]869 <tt>[40 x i32 ]</tt><br/>
870 <tt>[41 x i32 ]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]871 <tt>[40 x i8]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]872 </td>
873 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]874 Array of 40 32-bit integer values.<br/>
875 Array of 41 32-bit integer values.<br/>
876 Array of 40 8-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]877 </td>
878 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]879</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]880<p>Here are some examples of multidimensional arrays:</p>
881<table class="layout">
882 <tr class="layout">
883 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]884 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]885 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]886 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]887 </td>
888 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]889 3x4 array of 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]890 12x10 array of single precision floating point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]891 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]892 </td>
893 </tr>
894</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]895
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]896<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
897length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]898LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
899As a special case, however, zero length arrays are recognized to be variable
900length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]901type "{ i32, [0 x float]}", for example.</p>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]902
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]903</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]904
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]905<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]906<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]907<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]908<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]909<p>The function type can be thought of as a function signature. It
910consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]911Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]912(which are structures of pointers to functions), for indirect function
913calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]914<p>
915The return type of a function type cannot be an aggregate type.
916</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]917<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]918<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]919<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]920specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]921which indicates that the function takes a variable number of arguments.
922Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]923 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]924<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]925<table class="layout">
926 <tr class="layout">
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]927 <td class="left"><tt>i32 (i32)</tt></td>
928 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]929 </td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]930 </tr><tr class="layout">
Reid Spencer7bf214d2007-01-15 18:28:34 +0000[diff] [blame]931 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencerf17a0b72006-12-31 07:20:23 +0000[diff] [blame]932 </tt></td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]933 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
934 an <tt>i16</tt> that should be sign extended and a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]935 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]936 <tt>float</tt>.
937 </td>
938 </tr><tr class="layout">
939 <td class="left"><tt>i32 (i8*, ...)</tt></td>
940 <td class="left">A vararg function that takes at least one
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]941 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]942 which returns an integer. This is the signature for <tt>printf</tt> in
943 LLVM.
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]944 </td>
945 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]946</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]947
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]948</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]949<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]950<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]951<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]952<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]953<p>The structure type is used to represent a collection of data members
954together in memory. The packing of the field types is defined to match
955the ABI of the underlying processor. The elements of a structure may
956be any type that has a size.</p>
957<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
958and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
959field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
960instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]961<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]962<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]963<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]964<table class="layout">
965 <tr class="layout">
966 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]967 <tt>{ i32, i32, i32 }</tt><br/>
968 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]969 </td>
970 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]971 a triple of three <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]972 A pair, where the first element is a <tt>float</tt> and the second element
973 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]974 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]975 </td>
976 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]977</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]978</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]979
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]980<!-- _______________________________________________________________________ -->
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]981<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
982</div>
983<div class="doc_text">
984<h5>Overview:</h5>
985<p>The packed structure type is used to represent a collection of data members
986together in memory. There is no padding between fields. Further, the alignment
987of a packed structure is 1 byte. The elements of a packed structure may
988be any type that has a size.</p>
989<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
990and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
991field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
992instruction.</p>
993<h5>Syntax:</h5>
994<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
995<h5>Examples:</h5>
996<table class="layout">
997 <tr class="layout">
998 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]999 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1000 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1001 </td>
1002 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1003 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1004 A pair, where the first element is a <tt>float</tt> and the second element
1005 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]1006 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1007 </td>
1008 </tr>
1009</table>
1010</div>
1011
1012<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1013<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1014<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1015<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1016<p>As in many languages, the pointer type represents a pointer or
1017reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1018<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1019<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1020<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1021<table class="layout">
1022 <tr class="layout">
1023 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1024 <tt>[4x i32]*</tt><br/>
1025 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1026 </td>
1027 <td class="left">
1028 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]1029 four <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1030 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1031 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1032 <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1033 </td>
1034 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1035</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1036</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1037
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1038<!-- _______________________________________________________________________ -->
1039<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1040<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1041
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1042<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1043
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1044<p>A packed type is a simple derived type that represents a vector
1045of elements. Packed types are used when multiple primitive data
1046are operated in parallel using a single instruction (SIMD).
1047A packed type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]1048elements) and an underlying primitive data type. Vectors must have a power
1049of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1050considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1051
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1052<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1053
1054<pre>
1055 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1056</pre>
1057
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1058<p>The number of elements is a constant integer value; elementtype may
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1059be any integer or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1060
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1061<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1062
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1063<table class="layout">
1064 <tr class="layout">
1065 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1066 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1067 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1068 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1069 </td>
1070 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1071 Packed vector of 4 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1072 Packed vector of 8 floating-point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1073 Packed vector of 2 64-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1074 </td>
1075 </tr>
1076</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1077</div>
1078
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1079<!-- _______________________________________________________________________ -->
1080<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1081<div class="doc_text">
1082
1083<h5>Overview:</h5>
1084
1085<p>Opaque types are used to represent unknown types in the system. This
1086corresponds (for example) to the C notion of a foward declared structure type.
1087In LLVM, opaque types can eventually be resolved to any type (not just a
1088structure type).</p>
1089
1090<h5>Syntax:</h5>
1091
1092<pre>
1093 opaque
1094</pre>
1095
1096<h5>Examples:</h5>
1097
1098<table class="layout">
1099 <tr class="layout">
1100 <td class="left">
1101 <tt>opaque</tt>
1102 </td>
1103 <td class="left">
1104 An opaque type.<br/>
1105 </td>
1106 </tr>
1107</table>
1108</div>
1109
1110
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1111<!-- *********************************************************************** -->
1112<div class="doc_section"> <a name="constants">Constants</a> </div>
1113<!-- *********************************************************************** -->
1114
1115<div class="doc_text">
1116
1117<p>LLVM has several different basic types of constants. This section describes
1118them all and their syntax.</p>
1119
1120</div>
1121
1122<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1123<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1124
1125<div class="doc_text">
1126
1127<dl>
1128 <dt><b>Boolean constants</b></dt>
1129
1130 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1131 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1132 </dd>
1133
1134 <dt><b>Integer constants</b></dt>
1135
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1136 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1137 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1138 integer types.
1139 </dd>
1140
1141 <dt><b>Floating point constants</b></dt>
1142
1143 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1144 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1145 notation (see below). Floating point constants must have a <a
1146 href="#t_floating">floating point</a> type. </dd>
1147
1148 <dt><b>Null pointer constants</b></dt>
1149
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1150 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1151 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1152
1153</dl>
1154
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1155<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1156of floating point constants. For example, the form '<tt>double
11570x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
11584.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1159(and the only time that they are generated by the disassembler) is when a
1160floating point constant must be emitted but it cannot be represented as a
1161decimal floating point number. For example, NaN's, infinities, and other
1162special values are represented in their IEEE hexadecimal format so that
1163assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1164
1165</div>
1166
1167<!-- ======================================================================= -->
1168<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1169</div>
1170
1171<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1172<p>Aggregate constants arise from aggregation of simple constants
1173and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1174
1175<dl>
1176 <dt><b>Structure constants</b></dt>
1177
1178 <dd>Structure constants are represented with notation similar to structure
1179 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1180 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1181 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]1182 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1183 types of elements must match those specified by the type.
1184 </dd>
1185
1186 <dt><b>Array constants</b></dt>
1187
1188 <dd>Array constants are represented with notation similar to array type
1189 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1190 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1191 constants must have <a href="#t_array">array type</a>, and the number and
1192 types of elements must match those specified by the type.
1193 </dd>
1194
1195 <dt><b>Packed constants</b></dt>
1196
1197 <dd>Packed constants are represented with notation similar to packed type
1198 definitions (a comma separated list of elements, surrounded by
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1199 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1200 i32 11, i32 74, i32 100 &gt;</tt>". Packed constants must have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1201 href="#t_packed">packed type</a>, and the number and types of elements must
1202 match those specified by the type.
1203 </dd>
1204
1205 <dt><b>Zero initialization</b></dt>
1206
1207 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1208 value to zero of <em>any</em> type, including scalar and aggregate types.
1209 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]1210 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1211 initializers.
1212 </dd>
1213</dl>
1214
1215</div>
1216
1217<!-- ======================================================================= -->
1218<div class="doc_subsection">
1219 <a name="globalconstants">Global Variable and Function Addresses</a>
1220</div>
1221
1222<div class="doc_text">
1223
1224<p>The addresses of <a href="#globalvars">global variables</a> and <a
1225href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1226constants. These constants are explicitly referenced when the <a
1227href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1228href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1229file:</p>
1230
1231<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1232 %X = global i32 17
1233 %Y = global i32 42
1234 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1235</pre>
1236
1237</div>
1238
1239<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1240<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1241<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1242 <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]1243 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1244 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1245
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1246 <p>Undefined values indicate to the compiler that the program is well defined
1247 no matter what value is used, giving the compiler more freedom to optimize.
1248 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1249</div>
1250
1251<!-- ======================================================================= -->
1252<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1253</div>
1254
1255<div class="doc_text">
1256
1257<p>Constant expressions are used to allow expressions involving other constants
1258to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1259href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1260that does not have side effects (e.g. load and call are not supported). The
1261following is the syntax for constant expressions:</p>
1262
1263<dl>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1264 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1265 <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]1266 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1267
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1268 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1269 <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]1270 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]1271
1272 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1273 <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]1274 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]1275
1276 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1277 <dd>Truncate a floating point constant to another floating point type. The
1278 size of CST must be larger than the size of TYPE. Both types must be
1279 floating point.</dd>
1280
1281 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1282 <dd>Floating point extend a constant to another type. The size of CST must be
1283 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1284
1285 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1286 <dd>Convert a floating point constant to the corresponding unsigned integer
1287 constant. TYPE must be an integer type. CST must be floating point. If the
1288 value won't fit in the integer type, the results are undefined.</dd>
1289
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1290 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1291 <dd>Convert a floating point constant to the corresponding signed integer
1292 constant. TYPE must be an integer type. CST must be floating point. If the
1293 value won't fit in the integer type, the results are undefined.</dd>
1294
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1295 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1296 <dd>Convert an unsigned integer constant to the corresponding floating point
1297 constant. TYPE must be floating point. CST must be of integer type. If the
1298 value won't fit in the floating point type, the results are undefined.</dd>
1299
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1300 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1301 <dd>Convert a signed integer constant to the corresponding floating point
1302 constant. TYPE must be floating point. CST must be of integer type. If the
1303 value won't fit in the floating point type, the results are undefined.</dd>
1304
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1305 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1306 <dd>Convert a pointer typed constant to the corresponding integer constant
1307 TYPE must be an integer type. CST must be of pointer type. The CST value is
1308 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1309
1310 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1311 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1312 pointer type. CST must be of integer type. The CST value is zero extended,
1313 truncated, or unchanged to make it fit in a pointer size. This one is
1314 <i>really</i> dangerous!</dd>
1315
1316 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1317 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1318 identical (same number of bits). The conversion is done as if the CST value
1319 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]1320 with this operator, just the type. This can be used for conversion of
1321 packed types to any other type, as long as they have the same bit width. For
1322 pointers it is only valid to cast to another pointer type.
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1323 </dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1324
1325 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1326
1327 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1328 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1329 instruction, the index list may have zero or more indexes, which are required
1330 to make sense for the type of "CSTPTR".</dd>
1331
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1332 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1333
1334 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1335 constants.</dd>
1336
1337 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1338 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1339
1340 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1341 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1342
1343 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1344
1345 <dd>Perform the <a href="#i_extractelement">extractelement
1346 operation</a> on constants.
1347
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1348 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1349
1350 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1351 operation</a> on constants.</dd>
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1352
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1353
1354 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1355
1356 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1357 operation</a> on constants.</dd>
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1358
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1359 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1360
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1361 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1362 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1363 binary</a> operations. The constraints on operands are the same as those for
1364 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1365 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1366</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1367</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1368
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1369<!-- *********************************************************************** -->
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1370<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1371<!-- *********************************************************************** -->
1372
1373<!-- ======================================================================= -->
1374<div class="doc_subsection">
1375<a name="inlineasm">Inline Assembler Expressions</a>
1376</div>
1377
1378<div class="doc_text">
1379
1380<p>
1381LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1382Module-Level Inline Assembly</a>) through the use of a special value. This
1383value represents the inline assembler as a string (containing the instructions
1384to emit), a list of operand constraints (stored as a string), and a flag that
1385indicates whether or not the inline asm expression has side effects. An example
1386inline assembler expression is:
1387</p>
1388
1389<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1390 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1391</pre>
1392
1393<p>
1394Inline assembler expressions may <b>only</b> be used as the callee operand of
1395a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1396</p>
1397
1398<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1399 %X = call i32 asm "<a href="#i_bswap">bswap</a> $0", "=r,r"(i32 %Y)
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1400</pre>
1401
1402<p>
1403Inline asms with side effects not visible in the constraint list must be marked
1404as having side effects. This is done through the use of the
1405'<tt>sideeffect</tt>' keyword, like so:
1406</p>
1407
1408<pre>
1409 call void asm sideeffect "eieio", ""()
1410</pre>
1411
1412<p>TODO: The format of the asm and constraints string still need to be
1413documented here. Constraints on what can be done (e.g. duplication, moving, etc
1414need to be documented).
1415</p>
1416
1417</div>
1418
1419<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1420<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1421<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1422
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1423<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1424
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1425<p>The LLVM instruction set consists of several different
1426classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1427instructions</a>, <a href="#binaryops">binary instructions</a>,
1428<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1429 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1430instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1431
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1432</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1433
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1434<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1435<div class="doc_subsection"> <a name="terminators">Terminator
1436Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1437
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1438<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1439
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1440<p>As mentioned <a href="#functionstructure">previously</a>, every
1441basic block in a program ends with a "Terminator" instruction, which
1442indicates which block should be executed after the current block is
1443finished. These terminator instructions typically yield a '<tt>void</tt>'
1444value: they produce control flow, not values (the one exception being
1445the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1446<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1447 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1448instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1449the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1450 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1451 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1452
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1453</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1454
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1455<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1456<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1457Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1458<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1459<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1460<pre> 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]1461 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1462</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1463<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1464<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1465value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1466<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1467returns a value and then causes control flow, and one that just causes
1468control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1469<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1470<p>The '<tt>ret</tt>' instruction may return any '<a
1471 href="#t_firstclass">first class</a>' type. Notice that a function is
1472not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1473instruction inside of the function that returns a value that does not
1474match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1475<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1476<p>When the '<tt>ret</tt>' instruction is executed, control flow
1477returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1478 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1479the instruction after the call. If the caller was an "<a
1480 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1481at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1482returns a value, that value shall set the call or invoke instruction's
1483return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1484<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1485<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1486 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1487</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1488</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1489<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1490<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1491<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1492<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1493<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]1494</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1495<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1496<p>The '<tt>br</tt>' instruction is used to cause control flow to
1497transfer to a different basic block in the current function. There are
1498two forms of this instruction, corresponding to a conditional branch
1499and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1500<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1501<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1502single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1503unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1504value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1505<h5>Semantics:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1506<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1507argument is evaluated. If the value is <tt>true</tt>, control flows
1508to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1509control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1510<h5>Example:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1511<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]1512 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]1513</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1514<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1515<div class="doc_subsubsection">
1516 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1517</div>
1518
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1519<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1520<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1521
1522<pre>
1523 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1524</pre>
1525
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1526<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1527
1528<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1529several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1530instruction, allowing a branch to occur to one of many possible
1531destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1532
1533
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1534<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1535
1536<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1537comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1538an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1539table is not allowed to contain duplicate constant entries.</p>
1540
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1541<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1542
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1543<p>The <tt>switch</tt> instruction specifies a table of values and
1544destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1545table is searched for the given value. If the value is found, control flow is
1546transfered to the corresponding destination; otherwise, control flow is
1547transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1548
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1549<h5>Implementation:</h5>
1550
1551<p>Depending on properties of the target machine and the particular
1552<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1553ways. For example, it could be generated as a series of chained conditional
1554branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1555
1556<h5>Example:</h5>
1557
1558<pre>
1559 <i>; Emulate a conditional br instruction</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1560 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1561 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1562
1563 <i>; Emulate an unconditional br instruction</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1564 switch i32 0, label %dest [ ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1565
1566 <i>; Implement a jump table:</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1567 switch i32 %val, label %otherwise [ i32 0, label %onzero
1568 i32 1, label %onone
1569 i32 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1570</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1571</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1572
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1573<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1574<div class="doc_subsubsection">
1575 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1576</div>
1577
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1578<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1579
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1580<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1581
1582<pre>
1583 &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]1584 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1585</pre>
1586
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1587<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1588
1589<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1590function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1591'<tt>normal</tt>' label or the
1592'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1593"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1594"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1595href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1596continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1597
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1598<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1599
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1600<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1601
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1602<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1603 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1604 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1605 convention</a> the call should use. If none is specified, the call defaults
1606 to using C calling conventions.
1607 </li>
1608 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1609 function value being invoked. In most cases, this is a direct function
1610 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1611 an arbitrary pointer to function value.
1612 </li>
1613
1614 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1615 function to be invoked. </li>
1616
1617 <li>'<tt>function args</tt>': argument list whose types match the function
1618 signature argument types. If the function signature indicates the function
1619 accepts a variable number of arguments, the extra arguments can be
1620 specified. </li>
1621
1622 <li>'<tt>normal label</tt>': the label reached when the called function
1623 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1624
1625 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1626 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1627
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1628</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1629
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1630<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1631
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1632<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1633href="#i_call">call</a></tt>' instruction in most regards. The primary
1634difference is that it establishes an association with a label, which is used by
1635the runtime library to unwind the stack.</p>
1636
1637<p>This instruction is used in languages with destructors to ensure that proper
1638cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1639exception. Additionally, this is important for implementation of
1640'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1641
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1642<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1643<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1644 %retval = invoke i32 %Test(i32 15) to label %Continue
1645 unwind label %TestCleanup <i>; {i32}:retval set</i>
1646 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1647 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1648</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1649</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1650
1651
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1652<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1653
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1654<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1655Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1656
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1657<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1658
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1659<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1660<pre>
1661 unwind
1662</pre>
1663
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1664<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1665
1666<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1667at the first callee in the dynamic call stack which used an <a
1668href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1669primarily used to implement exception handling.</p>
1670
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1671<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1672
1673<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1674immediately halt. The dynamic call stack is then searched for the first <a
1675href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1676execution continues at the "exceptional" destination block specified by the
1677<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1678dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1679</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1680
1681<!-- _______________________________________________________________________ -->
1682
1683<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1684Instruction</a> </div>
1685
1686<div class="doc_text">
1687
1688<h5>Syntax:</h5>
1689<pre>
1690 unreachable
1691</pre>
1692
1693<h5>Overview:</h5>
1694
1695<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1696instruction is used to inform the optimizer that a particular portion of the
1697code is not reachable. This can be used to indicate that the code after a
1698no-return function cannot be reached, and other facts.</p>
1699
1700<h5>Semantics:</h5>
1701
1702<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1703</div>
1704
1705
1706
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1707<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1708<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1709<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1710<p>Binary operators are used to do most of the computation in a
1711program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1712produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1713multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1714The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1715necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1716<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1717</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1718<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1719<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1720Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1721<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1722<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1723<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]1724</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1725<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1726<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1727<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1728<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1729 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1730 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1731Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1732<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1733<p>The value produced is the integer or floating point sum of the two
1734operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1735<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1736<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]1737</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1738</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1739<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1740<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1741Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1742<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1743<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1744<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]1745</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1746<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1747<p>The '<tt>sub</tt>' instruction returns the difference of its two
1748operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1749<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1750instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1751<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1752<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1753 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1754values.
1755This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1756Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1757<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1758<p>The value produced is the integer or floating point difference of
1759the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1760<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1761<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1762 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1763</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1764</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1765<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1766<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1767Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1768<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1769<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1770<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]1771</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1772<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1773<p>The '<tt>mul</tt>' instruction returns the product of its two
1774operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1775<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1776<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1777 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1778values.
1779This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1780Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1781<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1782<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1783two operands.</p>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1784<p>Because the operands are the same width, the result of an integer
1785multiplication is the same whether the operands should be deemed unsigned or
1786signed.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1787<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1788<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]1789</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1790</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1791<!-- _______________________________________________________________________ -->
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1792<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1793</a></div>
1794<div class="doc_text">
1795<h5>Syntax:</h5>
1796<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1797</pre>
1798<h5>Overview:</h5>
1799<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1800operands.</p>
1801<h5>Arguments:</h5>
1802<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1803<a href="#t_integer">integer</a> values. Both arguments must have identical
1804types. This instruction can also take <a href="#t_packed">packed</a> versions
1805of the values in which case the elements must be integers.</p>
1806<h5>Semantics:</h5>
1807<p>The value produced is the unsigned integer quotient of the two operands. This
1808instruction always performs an unsigned division operation, regardless of
1809whether the arguments are unsigned or not.</p>
1810<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1811<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]1812</pre>
1813</div>
1814<!-- _______________________________________________________________________ -->
1815<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1816</a> </div>
1817<div class="doc_text">
1818<h5>Syntax:</h5>
1819<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1820</pre>
1821<h5>Overview:</h5>
1822<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1823operands.</p>
1824<h5>Arguments:</h5>
1825<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1826<a href="#t_integer">integer</a> values. Both arguments must have identical
1827types. This instruction can also take <a href="#t_packed">packed</a> versions
1828of the values in which case the elements must be integers.</p>
1829<h5>Semantics:</h5>
1830<p>The value produced is the signed integer quotient of the two operands. This
1831instruction always performs a signed division operation, regardless of whether
1832the arguments are signed or not.</p>
1833<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1834<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]1835</pre>
1836</div>
1837<!-- _______________________________________________________________________ -->
1838<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1839Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1840<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1841<h5>Syntax:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1842<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]1843</pre>
1844<h5>Overview:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1845<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1846operands.</p>
1847<h5>Arguments:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1848<p>The two arguments to the '<tt>div</tt>' instruction must be
1849<a href="#t_floating">floating point</a> values. Both arguments must have
1850identical types. This instruction can also take <a href="#t_packed">packed</a>
1851versions of the values in which case the elements must be floating point.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1852<h5>Semantics:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1853<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1854<h5>Example:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1855<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]1856</pre>
1857</div>
1858<!-- _______________________________________________________________________ -->
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1859<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1860</div>
1861<div class="doc_text">
1862<h5>Syntax:</h5>
1863<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1864</pre>
1865<h5>Overview:</h5>
1866<p>The '<tt>urem</tt>' instruction returns the remainder from the
1867unsigned division of its two arguments.</p>
1868<h5>Arguments:</h5>
1869<p>The two arguments to the '<tt>urem</tt>' instruction must be
1870<a href="#t_integer">integer</a> values. Both arguments must have identical
1871types.</p>
1872<h5>Semantics:</h5>
1873<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1874This instruction always performs an unsigned division to get the remainder,
1875regardless of whether the arguments are unsigned or not.</p>
1876<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1877<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]1878</pre>
1879
1880</div>
1881<!-- _______________________________________________________________________ -->
1882<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1883Instruction</a> </div>
1884<div class="doc_text">
1885<h5>Syntax:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1886<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]1887</pre>
1888<h5>Overview:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1889<p>The '<tt>srem</tt>' instruction returns the remainder from the
1890signed division of its two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1891<h5>Arguments:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1892<p>The two arguments to the '<tt>srem</tt>' instruction must be
1893<a href="#t_integer">integer</a> values. Both arguments must have identical
1894types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1895<h5>Semantics:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1896<p>This instruction returns the <i>remainder</i> of a division (where the result
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1897has the same sign as the divisor), not the <i>modulus</i> (where the
1898result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1899information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1900 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1901Math Forum</a>.</p>
1902<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1903<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]1904</pre>
1905
1906</div>
1907<!-- _______________________________________________________________________ -->
1908<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
1909Instruction</a> </div>
1910<div class="doc_text">
1911<h5>Syntax:</h5>
1912<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1913</pre>
1914<h5>Overview:</h5>
1915<p>The '<tt>frem</tt>' instruction returns the remainder from the
1916division of its two operands.</p>
1917<h5>Arguments:</h5>
1918<p>The two arguments to the '<tt>frem</tt>' instruction must be
1919<a href="#t_floating">floating point</a> values. Both arguments must have
1920identical types.</p>
1921<h5>Semantics:</h5>
1922<p>This instruction returns the <i>remainder</i> of a division.</p>
1923<h5>Example:</h5>
1924<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]1925</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1926</div>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]1927
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1928<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1929<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1930Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1931<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1932<p>Bitwise binary operators are used to do various forms of
1933bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1934instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1935instructions. They require two operands, execute an operation on them,
1936and produce a single value. The resulting value of the bitwise binary
1937operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1938</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1939<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1940<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1941Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1942<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1943<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1944<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]1945</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1946<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1947<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1948its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1949<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1950<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1951 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1952identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1953<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1954<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1955<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1956<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1957<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1958 <tbody>
1959 <tr>
1960 <td>In0</td>
1961 <td>In1</td>
1962 <td>Out</td>
1963 </tr>
1964 <tr>
1965 <td>0</td>
1966 <td>0</td>
1967 <td>0</td>
1968 </tr>
1969 <tr>
1970 <td>0</td>
1971 <td>1</td>
1972 <td>0</td>
1973 </tr>
1974 <tr>
1975 <td>1</td>
1976 <td>0</td>
1977 <td>0</td>
1978 </tr>
1979 <tr>
1980 <td>1</td>
1981 <td>1</td>
1982 <td>1</td>
1983 </tr>
1984 </tbody>
1985</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1986</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1987<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1988<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
1989 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
1990 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1991</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1992</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1993<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1994<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1995<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1996<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1997<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]1998</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1999<h5>Overview:</h5>
2000<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2001or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2002<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2003<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2004 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2005identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2006<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2007<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2008<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2009<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2010<table border="1" cellspacing="0" cellpadding="4">
2011 <tbody>
2012 <tr>
2013 <td>In0</td>
2014 <td>In1</td>
2015 <td>Out</td>
2016 </tr>
2017 <tr>
2018 <td>0</td>
2019 <td>0</td>
2020 <td>0</td>
2021 </tr>
2022 <tr>
2023 <td>0</td>
2024 <td>1</td>
2025 <td>1</td>
2026 </tr>
2027 <tr>
2028 <td>1</td>
2029 <td>0</td>
2030 <td>1</td>
2031 </tr>
2032 <tr>
2033 <td>1</td>
2034 <td>1</td>
2035 <td>1</td>
2036 </tr>
2037 </tbody>
2038</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2039</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2040<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2041<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2042 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2043 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2044</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2045</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2046<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2047<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2048Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2049<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2050<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2051<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]2052</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2053<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2054<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2055or of its two operands. The <tt>xor</tt> is used to implement the
2056"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2057<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2058<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2059 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2060identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2061<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2062<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2063<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2064<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2065<table border="1" cellspacing="0" cellpadding="4">
2066 <tbody>
2067 <tr>
2068 <td>In0</td>
2069 <td>In1</td>
2070 <td>Out</td>
2071 </tr>
2072 <tr>
2073 <td>0</td>
2074 <td>0</td>
2075 <td>0</td>
2076 </tr>
2077 <tr>
2078 <td>0</td>
2079 <td>1</td>
2080 <td>1</td>
2081 </tr>
2082 <tr>
2083 <td>1</td>
2084 <td>0</td>
2085 <td>1</td>
2086 </tr>
2087 <tr>
2088 <td>1</td>
2089 <td>1</td>
2090 <td>0</td>
2091 </tr>
2092 </tbody>
2093</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2094</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2095<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2096<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2097<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2098 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2099 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2100 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2101</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2102</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2103<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2104<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2105Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2106<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2107<h5>Syntax:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2108<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2109</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2110<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2111<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2112the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2113<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2114<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2115 href="#t_integer">integer</a> type. The second argument must be an '<tt>i8</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2116type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2117<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2118<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2119<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2120<pre> &lt;result&gt; = shl i32 4, i8 %var <i>; yields {i32}:result = 4 &lt;&lt; %var</i>
2121 &lt;result&gt; = shl i32 4, i8 2 <i>; yields {i32}:result = 16</i>
2122 &lt;result&gt; = shl i32 1, i8 10 <i>; yields {i32}:result = 1024</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2123</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2124</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2125<!-- _______________________________________________________________________ -->
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2126<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2127Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2128<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2129<h5>Syntax:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2130<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2131</pre>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2132
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2133<h5>Overview:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2134<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2135operand shifted to the right a specified number of bits.</p>
2136
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2137<h5>Arguments:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2138<p>The first argument to the '<tt>lshr</tt>' instruction must be an <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2139 href="#t_integer">integer</a> type. The second argument must be an '<tt>i8</tt>' type.</p>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2140
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2141<h5>Semantics:</h5>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]2142<p>This instruction always performs a logical shift right operation. The
2143<tt>var2</tt> most significant bits will be filled with zero bits after the
2144shift.</p>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2145
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2146<h5>Example:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2147<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2148 &lt;result&gt; = lshr i32 4, i8 1 <i>; yields {i32}:result = 2</i>
2149 &lt;result&gt; = lshr i32 4, i8 2 <i>; yields {i32}:result = 1</i>
2150 &lt;result&gt; = lshr i8 4, i8 3 <i>; yields {i8 }:result = 0</i>
2151 &lt;result&gt; = lshr i8 -2, i8 1 <i>; yields {i8 }:result = 0x7FFFFFFF </i>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2152</pre>
2153</div>
2154
2155<!-- ======================================================================= -->
2156<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2157Instruction</a> </div>
2158<div class="doc_text">
2159
2160<h5>Syntax:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2161<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2162</pre>
2163
2164<h5>Overview:</h5>
2165<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2166operand shifted to the right a specified number of bits.</p>
2167
2168<h5>Arguments:</h5>
2169<p>The first argument to the '<tt>ashr</tt>' instruction must be an
2170<a href="#t_integer">integer</a> type. The second argument must be an
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2171'<tt>i8</tt>' type.</p>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2172
2173<h5>Semantics:</h5>
2174<p>This instruction always performs an arithmetic shift right operation,
2175regardless of whether the arguments are signed or not. The <tt>var2</tt> most
2176significant bits will be filled with the sign bit of <tt>var1</tt>.</p>
2177
2178<h5>Example:</h5>
2179<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2180 &lt;result&gt; = ashr i32 4, i8 1 <i>; yields {i32}:result = 2</i>
2181 &lt;result&gt; = ashr i32 4, i8 2 <i>; yields {i32}:result = 1</i>
2182 &lt;result&gt; = ashr i8 4, i8 3 <i>; yields {i8}:result = 0</i>
2183 &lt;result&gt; = ashr i8 -2, i8 1 <i>; yields {i8 }:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2184</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2185</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2186
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2187<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2188<div class="doc_subsection">
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2189 <a name="vectorops">Vector Operations</a>
2190</div>
2191
2192<div class="doc_text">
2193
2194<p>LLVM supports several instructions to represent vector operations in a
2195target-independent manner. This instructions cover the element-access and
2196vector-specific operations needed to process vectors effectively. While LLVM
2197does directly support these vector operations, many sophisticated algorithms
2198will want to use target-specific intrinsics to take full advantage of a specific
2199target.</p>
2200
2201</div>
2202
2203<!-- _______________________________________________________________________ -->
2204<div class="doc_subsubsection">
2205 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2206</div>
2207
2208<div class="doc_text">
2209
2210<h5>Syntax:</h5>
2211
2212<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2213 &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]2214</pre>
2215
2216<h5>Overview:</h5>
2217
2218<p>
2219The '<tt>extractelement</tt>' instruction extracts a single scalar
2220element from a packed vector at a specified index.
2221</p>
2222
2223
2224<h5>Arguments:</h5>
2225
2226<p>
2227The first operand of an '<tt>extractelement</tt>' instruction is a
2228value of <a href="#t_packed">packed</a> type. The second operand is
2229an index indicating the position from which to extract the element.
2230The index may be a variable.</p>
2231
2232<h5>Semantics:</h5>
2233
2234<p>
2235The result is a scalar of the same type as the element type of
2236<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2237<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2238results are undefined.
2239</p>
2240
2241<h5>Example:</h5>
2242
2243<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2244 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2245</pre>
2246</div>
2247
2248
2249<!-- _______________________________________________________________________ -->
2250<div class="doc_subsubsection">
2251 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2252</div>
2253
2254<div class="doc_text">
2255
2256<h5>Syntax:</h5>
2257
2258<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2259 &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]2260</pre>
2261
2262<h5>Overview:</h5>
2263
2264<p>
2265The '<tt>insertelement</tt>' instruction inserts a scalar
2266element into a packed vector at a specified index.
2267</p>
2268
2269
2270<h5>Arguments:</h5>
2271
2272<p>
2273The first operand of an '<tt>insertelement</tt>' instruction is a
2274value of <a href="#t_packed">packed</a> type. The second operand is a
2275scalar value whose type must equal the element type of the first
2276operand. The third operand is an index indicating the position at
2277which to insert the value. The index may be a variable.</p>
2278
2279<h5>Semantics:</h5>
2280
2281<p>
2282The result is a packed vector of the same type as <tt>val</tt>. Its
2283element values are those of <tt>val</tt> except at position
2284<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2285exceeds the length of <tt>val</tt>, the results are undefined.
2286</p>
2287
2288<h5>Example:</h5>
2289
2290<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2291 %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]2292</pre>
2293</div>
2294
2295<!-- _______________________________________________________________________ -->
2296<div class="doc_subsubsection">
2297 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2298</div>
2299
2300<div class="doc_text">
2301
2302<h5>Syntax:</h5>
2303
2304<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2305 &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]2306</pre>
2307
2308<h5>Overview:</h5>
2309
2310<p>
2311The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2312from two input vectors, returning a vector of the same type.
2313</p>
2314
2315<h5>Arguments:</h5>
2316
2317<p>
2318The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2319with types that match each other and types that match the result of the
2320instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2321of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2322</p>
2323
2324<p>
2325The shuffle mask operand is required to be a constant vector with either
2326constant integer or undef values.
2327</p>
2328
2329<h5>Semantics:</h5>
2330
2331<p>
2332The elements of the two input vectors are numbered from left to right across
2333both of the vectors. The shuffle mask operand specifies, for each element of
2334the result vector, which element of the two input registers the result element
2335gets. The element selector may be undef (meaning "don't care") and the second
2336operand may be undef if performing a shuffle from only one vector.
2337</p>
2338
2339<h5>Example:</h5>
2340
2341<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2342 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2343 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2344 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2345 &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]2346</pre>
2347</div>
2348
Tanya Lattner09474292006-04-14 19:24:33 +0000[diff] [blame]2349
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2350<!-- ======================================================================= -->
2351<div class="doc_subsection">
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2352 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2353</div>
2354
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2355<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2356
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2357<p>A key design point of an SSA-based representation is how it
2358represents memory. In LLVM, no memory locations are in SSA form, which
2359makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2360allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2361
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2362</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2363
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2364<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2365<div class="doc_subsubsection">
2366 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2367</div>
2368
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2369<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2370
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2371<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2372
2373<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2374 &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]2375</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2376
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2377<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2378
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2379<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2380heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2381
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2382<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2383
2384<p>The '<tt>malloc</tt>' instruction allocates
2385<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]2386bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2387appropriate type to the program. If "NumElements" is specified, it is the
2388number of elements allocated. If an alignment is specified, the value result
2389of the allocation is guaranteed to be aligned to at least that boundary. If
2390not specified, or if zero, the target can choose to align the allocation on any
2391convenient boundary.</p>
2392
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2393<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2394
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2395<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2396
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2397<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2398a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2399
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2400<h5>Example:</h5>
2401
2402<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2403 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2404
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2405 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2406 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2407 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2408 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2409 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2410</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2411</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2412
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2413<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2414<div class="doc_subsubsection">
2415 <a name="i_free">'<tt>free</tt>' Instruction</a>
2416</div>
2417
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2418<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2419
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2420<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2421
2422<pre>
2423 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2424</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2425
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2426<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2427
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2428<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2429memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2430
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2431<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2432
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2433<p>'<tt>value</tt>' shall be a pointer value that points to a value
2434that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2435instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2436
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2437<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2438
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2439<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2440after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2441
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2442<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2443
2444<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2445 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2446 free [4 x i8]* %array
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2447</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2448</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2449
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2450<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2451<div class="doc_subsubsection">
2452 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2453</div>
2454
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2455<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2456
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2457<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2458
2459<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2460 &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]2461</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2462
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2463<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2464
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2465<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2466stack frame of the procedure that is live until the current function
2467returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2468
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2469<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2470
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2471<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2472bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2473appropriate type to the program. If "NumElements" is specified, it is the
2474number of elements allocated. If an alignment is specified, the value result
2475of the allocation is guaranteed to be aligned to at least that boundary. If
2476not specified, or if zero, the target can choose to align the allocation on any
2477convenient boundary.</p>
2478
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2479<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2480
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2481<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2482
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2483<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2484memory is automatically released when the function returns. The '<tt>alloca</tt>'
2485instruction is commonly used to represent automatic variables that must
2486have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]2487 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]2488instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2489
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2490<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2491
2492<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2493 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2494 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2495 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2496 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2497</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2498</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2499
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2500<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2501<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2502Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2503<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2504<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2505<pre> &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;<br> &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;<br></pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2506<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2507<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2508<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2509<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2510address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2511 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2512marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2513the number or order of execution of this <tt>load</tt> with other
2514volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2515instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2516<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2517<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2518<h5>Examples:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2519<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2520 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2521 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2522 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2523</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2524</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2525<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2526<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2527Instruction</a> </div>
Reid Spencer035ab572006-11-09 21:18:01 +0000[diff] [blame]2528<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2529<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2530<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattnerf0651072003-09-08 18:27:49 +0000[diff] [blame]2531 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2532</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2533<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2534<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2535<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2536<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2537to 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]2538operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2539operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2540optimizer is not allowed to modify the number or order of execution of
2541this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2542 href="#i_store">store</a></tt> instructions.</p>
2543<h5>Semantics:</h5>
2544<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2545at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2546<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2547<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2548 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2549 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2550 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2551</pre>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2552</div>
2553
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2554<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2555<div class="doc_subsubsection">
2556 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2557</div>
2558
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2559<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2560<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2561<pre>
2562 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2563</pre>
2564
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2565<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2566
2567<p>
2568The '<tt>getelementptr</tt>' instruction is used to get the address of a
2569subelement of an aggregate data structure.</p>
2570
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2571<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2572
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2573<p>This instruction takes a list of integer operands that indicate what
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2574elements of the aggregate object to index to. The actual types of the arguments
2575provided depend on the type of the first pointer argument. The
2576'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2577levels 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]2578structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2579into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2580be sign extended to 64-bit values.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2581
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2582<p>For example, let's consider a C code fragment and how it gets
2583compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2584
2585<pre>
2586 struct RT {
2587 char A;
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2588 i32 B[10][20];
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2589 char C;
2590 };
2591 struct ST {
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2592 i32 X;
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2593 double Y;
2594 struct RT Z;
2595 };
2596
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2597 define i32 *foo(struct ST *s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2598 return &amp;s[1].Z.B[5][13];
2599 }
2600</pre>
2601
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2602<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2603
2604<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2605 %RT = type { i8 , [10 x [20 x i32]], i8 }
2606 %ST = type { i32, double, %RT }
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2607
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2608 implementation
2609
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2610 define i32* %foo(%ST* %s) {
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2611 entry:
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2612 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2613 ret i32* %reg
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2614 }
2615</pre>
2616
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2617<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2618
2619<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2620on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2621and <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]2622<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]2623to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencer42ddd842006-12-03 16:53:48 +0000[diff] [blame]2624<b>constants</b>.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2625
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2626<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]2627type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2628}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2629the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2630i8 }</tt>' type, another structure. The third index indexes into the second
2631element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2632array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2633'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2634to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2635
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2636<p>Note that it is perfectly legal to index partially through a
2637structure, returning a pointer to an inner element. Because of this,
2638the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2639
2640<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2641 define i32* %foo(%ST* %s) {
2642 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2643 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2644 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2645 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2646 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2647 ret i32* %t5
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2648 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2649</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2650
2651<p>Note that it is undefined to access an array out of bounds: array and
2652pointer indexes must always be within the defined bounds of the array type.
2653The one exception for this rules is zero length arrays. These arrays are
2654defined to be accessible as variable length arrays, which requires access
2655beyond the zero'th element.</p>
2656
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2657<p>The getelementptr instruction is often confusing. For some more insight
2658into how it works, see <a href="GetElementPtr.html">the getelementptr
2659FAQ</a>.</p>
2660
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2661<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2662
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2663<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2664 <i>; yields [12 x i8]*:aptr</i>
2665 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2666</pre>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2667</div>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2668
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2669<!-- ======================================================================= -->
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2670<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2671</div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2672<div class="doc_text">
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2673<p>The instructions in this category are the conversion instructions (casting)
2674which all take a single operand and a type. They perform various bit conversions
2675on the operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2676</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2677
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2678<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2679<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2680 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2681</div>
2682<div class="doc_text">
2683
2684<h5>Syntax:</h5>
2685<pre>
2686 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2687</pre>
2688
2689<h5>Overview:</h5>
2690<p>
2691The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2692</p>
2693
2694<h5>Arguments:</h5>
2695<p>
2696The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2697be 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]2698and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2699type. The bit size of <tt>value</tt> must be larger than the bit size of
2700<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2701
2702<h5>Semantics:</h5>
2703<p>
2704The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2705and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2706larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2707It will always truncate bits.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2708
2709<h5>Example:</h5>
2710<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2711 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2712 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2713 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2714</pre>
2715</div>
2716
2717<!-- _______________________________________________________________________ -->
2718<div class="doc_subsubsection">
2719 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2720</div>
2721<div class="doc_text">
2722
2723<h5>Syntax:</h5>
2724<pre>
2725 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2726</pre>
2727
2728<h5>Overview:</h5>
2729<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2730<tt>ty2</tt>.</p>
2731
2732
2733<h5>Arguments:</h5>
2734<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]2735<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2736also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2737<tt>value</tt> must be smaller than the bit size of the destination type,
2738<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2739
2740<h5>Semantics:</h5>
2741<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2742bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2743the operand and the type are the same size, no bit filling is done and the
2744cast is considered a <i>no-op cast</i> because no bits change (only the type
2745changes).</p>
2746
Reid Spencerb5929522007-01-12 15:46:11 +0000[diff] [blame]2747<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]2748
2749<h5>Example:</h5>
2750<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2751 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2752 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2753</pre>
2754</div>
2755
2756<!-- _______________________________________________________________________ -->
2757<div class="doc_subsubsection">
2758 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2759</div>
2760<div class="doc_text">
2761
2762<h5>Syntax:</h5>
2763<pre>
2764 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2765</pre>
2766
2767<h5>Overview:</h5>
2768<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2769
2770<h5>Arguments:</h5>
2771<p>
2772The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2773<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2774also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2775<tt>value</tt> must be smaller than the bit size of the destination type,
2776<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2777
2778<h5>Semantics:</h5>
2779<p>
2780The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2781bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2782the type <tt>ty2</tt>. When the the operand and the type are the same size,
2783no bit filling is done and the cast is considered a <i>no-op cast</i> because
2784no bits change (only the type changes).</p>
2785
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2786<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]2787
2788<h5>Example:</h5>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2789<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2790 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2791 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2792</pre>
2793</div>
2794
2795<!-- _______________________________________________________________________ -->
2796<div class="doc_subsubsection">
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2797 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2798</div>
2799
2800<div class="doc_text">
2801
2802<h5>Syntax:</h5>
2803
2804<pre>
2805 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2806</pre>
2807
2808<h5>Overview:</h5>
2809<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2810<tt>ty2</tt>.</p>
2811
2812
2813<h5>Arguments:</h5>
2814<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2815 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2816cast it to. The size of <tt>value</tt> must be larger than the size of
2817<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2818<i>no-op cast</i>.</p>
2819
2820<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2821<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2822<a href="#t_floating">floating point</a> type to a smaller
2823<a href="#t_floating">floating point</a> type. If the value cannot fit within
2824the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2825
2826<h5>Example:</h5>
2827<pre>
2828 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2829 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2830</pre>
2831</div>
2832
2833<!-- _______________________________________________________________________ -->
2834<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2835 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2836</div>
2837<div class="doc_text">
2838
2839<h5>Syntax:</h5>
2840<pre>
2841 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2842</pre>
2843
2844<h5>Overview:</h5>
2845<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2846floating point value.</p>
2847
2848<h5>Arguments:</h5>
2849<p>The '<tt>fpext</tt>' instruction takes a
2850<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2851and a <a href="#t_floating">floating point</a> type to cast it to. The source
2852type must be smaller than the destination type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2853
2854<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2855<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
2856<a href="t_floating">floating point</a> type to a larger
2857<a href="t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
2858used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]2859<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]2860
2861<h5>Example:</h5>
2862<pre>
2863 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2864 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2865</pre>
2866</div>
2867
2868<!-- _______________________________________________________________________ -->
2869<div class="doc_subsubsection">
Reid Spencer24d6da52007-01-21 00:29:26 +0000[diff] [blame]2870 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2871</div>
2872<div class="doc_text">
2873
2874<h5>Syntax:</h5>
2875<pre>
2876 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2877</pre>
2878
2879<h5>Overview:</h5>
2880<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2881unsigned integer equivalent of type <tt>ty2</tt>.
2882</p>
2883
2884<h5>Arguments:</h5>
2885<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2886<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]2887must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2888
2889<h5>Semantics:</h5>
2890<p> The '<tt>fp2uint</tt>' instruction converts its
2891<a href="#t_floating">floating point</a> operand into the nearest (rounding
2892towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2893the results are undefined.</p>
2894
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2895<p>When converting to i1, the conversion is done as a comparison against
2896zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2897If 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]2898
2899<h5>Example:</h5>
2900<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2901 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
2902 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2903 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2904</pre>
2905</div>
2906
2907<!-- _______________________________________________________________________ -->
2908<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2909 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2910</div>
2911<div class="doc_text">
2912
2913<h5>Syntax:</h5>
2914<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2915 &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]2916</pre>
2917
2918<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2919<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2920<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]2921</p>
2922
2923
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2924<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2925<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]2926<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]2927must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2928
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2929<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2930<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2931<a href="#t_floating">floating point</a> operand into the nearest (rounding
2932towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
2933the results are undefined.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2934
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2935<p>When converting to i1, the conversion is done as a comparison against
2936zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2937If 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]2938
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2939<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2940<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2941 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
2942 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2943 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2944</pre>
2945</div>
2946
2947<!-- _______________________________________________________________________ -->
2948<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2949 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2950</div>
2951<div class="doc_text">
2952
2953<h5>Syntax:</h5>
2954<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2955 &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]2956</pre>
2957
2958<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2959<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2960integer and converts that value to the <tt>ty2</tt> type.</p>
2961
2962
2963<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2964<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]2965<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]2966be a <a href="#t_floating">floating point</a> type.</p>
2967
2968<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2969<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2970integer quantity and converts it to the corresponding floating point value. If
2971the value cannot fit in the floating point value, the results are undefined.</p>
2972
2973
2974<h5>Example:</h5>
2975<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2976 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
2977 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2978</pre>
2979</div>
2980
2981<!-- _______________________________________________________________________ -->
2982<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2983 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2984</div>
2985<div class="doc_text">
2986
2987<h5>Syntax:</h5>
2988<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2989 &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]2990</pre>
2991
2992<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2993<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2994integer and converts that value to the <tt>ty2</tt> type.</p>
2995
2996<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2997<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]2998<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]2999a <a href="#t_floating">floating point</a> type.</p>
3000
3001<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3002<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3003integer quantity and converts it to the corresponding floating point value. If
3004the value cannot fit in the floating point value, the results are undefined.</p>
3005
3006<h5>Example:</h5>
3007<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3008 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3009 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3010</pre>
3011</div>
3012
3013<!-- _______________________________________________________________________ -->
3014<div class="doc_subsubsection">
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3015 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3016</div>
3017<div class="doc_text">
3018
3019<h5>Syntax:</h5>
3020<pre>
3021 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3022</pre>
3023
3024<h5>Overview:</h5>
3025<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3026the integer type <tt>ty2</tt>.</p>
3027
3028<h5>Arguments:</h5>
3029<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3030must be a <a href="t_pointer">pointer</a> value, and a type to cast it to
3031<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3032
3033<h5>Semantics:</h5>
3034<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3035<tt>ty2</tt> by interpreting the pointer value as an integer and either
3036truncating or zero extending that value to the size of the integer type. If
3037<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3038<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3039are the same size, then nothing is done (<i>no-op cast</i>).</p>
3040
3041<h5>Example:</h5>
3042<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3043 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3044 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3045</pre>
3046</div>
3047
3048<!-- _______________________________________________________________________ -->
3049<div class="doc_subsubsection">
3050 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3051</div>
3052<div class="doc_text">
3053
3054<h5>Syntax:</h5>
3055<pre>
3056 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3057</pre>
3058
3059<h5>Overview:</h5>
3060<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3061a pointer type, <tt>ty2</tt>.</p>
3062
3063<h5>Arguments:</h5>
3064<p>The '<tt>inttoptr</tt>' instruction takes an <a href="i_integer">integer</a>
3065value to cast, and a type to cast it to, which must be a
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]3066<a href="#t_pointer">pointer</a> type.
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3067
3068<h5>Semantics:</h5>
3069<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3070<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3071the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3072size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3073the size of a pointer then a zero extension is done. If they are the same size,
3074nothing is done (<i>no-op cast</i>).</p>
3075
3076<h5>Example:</h5>
3077<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3078 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3079 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3080 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3081</pre>
3082</div>
3083
3084<!-- _______________________________________________________________________ -->
3085<div class="doc_subsubsection">
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3086 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3087</div>
3088<div class="doc_text">
3089
3090<h5>Syntax:</h5>
3091<pre>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3092 &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]3093</pre>
3094
3095<h5>Overview:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3096<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3097<tt>ty2</tt> without changing any bits.</p>
3098
3099<h5>Arguments:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3100<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3101a first class value, and a type to cast it to, which must also be a <a
3102 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencer19b569f2007-01-09 20:08:58 +0000[diff] [blame]3103and the destination type, <tt>ty2</tt>, must be identical. If the source
3104type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3105
3106<h5>Semantics:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3107<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3108<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3109this conversion. The conversion is done as if the <tt>value</tt> had been
3110stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3111converted to other pointer types with this instruction. To convert pointers to
3112other types, use the <a href="#i_inttoptr">inttoptr</a> or
3113<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3114
3115<h5>Example:</h5>
3116<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3117 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3118 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3119 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]3120</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3121</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3122
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3123<!-- ======================================================================= -->
3124<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3125<div class="doc_text">
3126<p>The instructions in this category are the "miscellaneous"
3127instructions, which defy better classification.</p>
3128</div>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3129
3130<!-- _______________________________________________________________________ -->
3131<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3132</div>
3133<div class="doc_text">
3134<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3135<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3136<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3137</pre>
3138<h5>Overview:</h5>
3139<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3140of its two integer operands.</p>
3141<h5>Arguments:</h5>
3142<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3143the condition code which indicates the kind of comparison to perform. It is not
3144a value, just a keyword. The possibilities for the condition code are:
3145<ol>
3146 <li><tt>eq</tt>: equal</li>
3147 <li><tt>ne</tt>: not equal </li>
3148 <li><tt>ugt</tt>: unsigned greater than</li>
3149 <li><tt>uge</tt>: unsigned greater or equal</li>
3150 <li><tt>ult</tt>: unsigned less than</li>
3151 <li><tt>ule</tt>: unsigned less or equal</li>
3152 <li><tt>sgt</tt>: signed greater than</li>
3153 <li><tt>sge</tt>: signed greater or equal</li>
3154 <li><tt>slt</tt>: signed less than</li>
3155 <li><tt>sle</tt>: signed less or equal</li>
3156</ol>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3157<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3158<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3159<h5>Semantics:</h5>
3160<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3161the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3162yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3163<ol>
3164 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3165 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3166 </li>
3167 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3168 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3169 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3170 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3171 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3172 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3173 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3174 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3175 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3176 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3177 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3178 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3179 <li><tt>sge</tt>: interprets the operands as signed values and yields
3180 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3181 <li><tt>slt</tt>: interprets the operands as signed values and yields
3182 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3183 <li><tt>sle</tt>: interprets the operands as signed values and yields
3184 <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]3185</ol>
3186<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3187values are treated as integers and then compared.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3188
3189<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3190<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3191 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3192 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3193 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3194 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3195 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3196</pre>
3197</div>
3198
3199<!-- _______________________________________________________________________ -->
3200<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3201</div>
3202<div class="doc_text">
3203<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3204<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3205<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3206</pre>
3207<h5>Overview:</h5>
3208<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3209of its floating point operands.</p>
3210<h5>Arguments:</h5>
3211<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3212the condition code which indicates the kind of comparison to perform. It is not
3213a value, just a keyword. The possibilities for the condition code are:
3214<ol>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3215 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3216 <li><tt>oeq</tt>: ordered and equal</li>
3217 <li><tt>ogt</tt>: ordered and greater than </li>
3218 <li><tt>oge</tt>: ordered and greater than or equal</li>
3219 <li><tt>olt</tt>: ordered and less than </li>
3220 <li><tt>ole</tt>: ordered and less than or equal</li>
3221 <li><tt>one</tt>: ordered and not equal</li>
3222 <li><tt>ord</tt>: ordered (no nans)</li>
3223 <li><tt>ueq</tt>: unordered or equal</li>
3224 <li><tt>ugt</tt>: unordered or greater than </li>
3225 <li><tt>uge</tt>: unordered or greater than or equal</li>
3226 <li><tt>ult</tt>: unordered or less than </li>
3227 <li><tt>ule</tt>: unordered or less than or equal</li>
3228 <li><tt>une</tt>: unordered or not equal</li>
3229 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3230 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3231</ol>
Reid Spencer93a49852006-12-06 07:08:07 +0000[diff] [blame]3232<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3233<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3234<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3235<a href="#t_floating">floating point</a> typed. They must have identical
3236types.</p>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3237<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3238<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3239<h5>Semantics:</h5>
3240<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3241the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3242yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3243<ol>
3244 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3245 <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]3246 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3247 <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]3248 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3249 <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]3250 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3251 <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]3252 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3253 <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]3254 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3255 <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]3256 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3257 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3258 <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]3259 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3260 <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]3261 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3262 <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]3263 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3264 <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]3265 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3266 <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]3267 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3268 <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]3269 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3270 <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]3271 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3272</ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3273
3274<h5>Example:</h5>
3275<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3276 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3277 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3278 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3279</pre>
3280</div>
3281
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3282<!-- _______________________________________________________________________ -->
3283<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3284Instruction</a> </div>
3285<div class="doc_text">
3286<h5>Syntax:</h5>
3287<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3288<h5>Overview:</h5>
3289<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3290the SSA graph representing the function.</p>
3291<h5>Arguments:</h5>
3292<p>The type of the incoming values are specified with the first type
3293field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3294as arguments, with one pair for each predecessor basic block of the
3295current block. Only values of <a href="#t_firstclass">first class</a>
3296type may be used as the value arguments to the PHI node. Only labels
3297may be used as the label arguments.</p>
3298<p>There must be no non-phi instructions between the start of a basic
3299block and the PHI instructions: i.e. PHI instructions must be first in
3300a basic block.</p>
3301<h5>Semantics:</h5>
3302<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3303value specified by the parameter, depending on which basic block we
3304came from in the last <a href="#terminators">terminator</a> instruction.</p>
3305<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3306<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]3307</div>
3308
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3309<!-- _______________________________________________________________________ -->
3310<div class="doc_subsubsection">
3311 <a name="i_select">'<tt>select</tt>' Instruction</a>
3312</div>
3313
3314<div class="doc_text">
3315
3316<h5>Syntax:</h5>
3317
3318<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3319 &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]3320</pre>
3321
3322<h5>Overview:</h5>
3323
3324<p>
3325The '<tt>select</tt>' instruction is used to choose one value based on a
3326condition, without branching.
3327</p>
3328
3329
3330<h5>Arguments:</h5>
3331
3332<p>
3333The '<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.
3334</p>
3335
3336<h5>Semantics:</h5>
3337
3338<p>
3339If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3340value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3341</p>
3342
3343<h5>Example:</h5>
3344
3345<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3346 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3347</pre>
3348</div>
3349
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]3350
3351<!-- _______________________________________________________________________ -->
3352<div class="doc_subsubsection">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3353 <a name="i_call">'<tt>call</tt>' Instruction</a>
3354</div>
3355
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3356<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3357
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3358<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3359<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3360 &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]3361</pre>
3362
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3363<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3364
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3365<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3366
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3367<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3368
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3369<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3370
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3371<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3372 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3373 <p>The optional "tail" marker indicates whether the callee function accesses
3374 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3375 function call is eligible for tail call optimization. Note that calls may
3376 be marked "tail" even if they do not occur before a <a
3377 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3378 </li>
3379 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3380 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
3381 convention</a> the call should use. If none is specified, the call defaults
3382 to using C calling conventions.
3383 </li>
3384 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3385 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3386 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3387 signature. This type can be omitted if the function is not varargs and
3388 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3389 </li>
3390 <li>
3391 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3392 be invoked. In most cases, this is a direct function invocation, but
3393 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3394 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3395 </li>
3396 <li>
3397 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]3398 function signature argument types. All arguments must be of
3399 <a href="#t_firstclass">first class</a> type. If the function signature
3400 indicates the function accepts a variable number of arguments, the extra
3401 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3402 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3403</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3404
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3405<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3406
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3407<p>The '<tt>call</tt>' instruction is used to cause control flow to
3408transfer to a specified function, with its incoming arguments bound to
3409the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3410instruction in the called function, control flow continues with the
3411instruction after the function call, and the return value of the
3412function is bound to the result argument. This is a simpler case of
3413the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3414
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3415<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3416
3417<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3418 %retval = call i32 %test(i32 %argc)
3419 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3420 %X = tail call i32 %foo()
3421 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3422</pre>
3423
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3424</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3425
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3426<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3427<div class="doc_subsubsection">
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3428 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3429</div>
3430
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3431<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3432
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3433<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3434
3435<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3436 &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]3437</pre>
3438
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3439<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3440
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3441<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3442the "variable argument" area of a function call. It is used to implement the
3443<tt>va_arg</tt> macro in C.</p>
3444
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3445<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3446
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3447<p>This instruction takes a <tt>va_list*</tt> value and the type of
3448the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3449increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3450actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3451
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3452<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3453
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3454<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3455type from the specified <tt>va_list</tt> and causes the
3456<tt>va_list</tt> to point to the next argument. For more information,
3457see the variable argument handling <a href="#int_varargs">Intrinsic
3458Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3459
3460<p>It is legal for this instruction to be called in a function which does not
3461take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3462function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3463
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3464<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3465href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3466argument.</p>
3467
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3468<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3469
3470<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3471
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3472</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3473
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3474<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3475<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3476<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3477
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3478<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3479
3480<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3481well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3482restrictions. Overall, these instructions represent an extension mechanism for
3483the LLVM language that does not require changing all of the transformations in
3484LLVM to add to the language (or the bytecode reader/writer, the parser,
3485etc...).</p>
3486
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3487<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3488prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3489this. Intrinsic functions must always be external functions: you cannot define
3490the body of intrinsic functions. Intrinsic functions may only be used in call
3491or invoke instructions: it is illegal to take the address of an intrinsic
3492function. Additionally, because intrinsic functions are part of the LLVM
3493language, it is required that they all be documented here if any are added.</p>
3494
3495
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3496<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]3497href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3498</p>
3499
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3500</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3501
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3502<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3503<div class="doc_subsection">
3504 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3505</div>
3506
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3507<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3508
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3509<p>Variable argument support is defined in LLVM with the <a
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3510 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3511intrinsic functions. These functions are related to the similarly
3512named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3513
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3514<p>All of these functions operate on arguments that use a
3515target-specific value type "<tt>va_list</tt>". The LLVM assembly
3516language reference manual does not define what this type is, so all
3517transformations should be prepared to handle intrinsics with any type
3518used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3519
Chris Lattner374ab302006-05-15 17:26:46 +0000[diff] [blame]3520<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]3521instruction and the variable argument handling intrinsic functions are
3522used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3523
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3524<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3525define i32 %test(i32 %X, ...) {
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3526 ; Initialize variable argument processing
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3527 %ap = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3528 %ap2 = bitcast i8** %ap to i8*
3529 call void %<a href="#i_va_start">llvm.va_start</a>(i8* %ap2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3530
3531 ; Read a single integer argument
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3532 %tmp = va_arg i8 ** %ap, i32
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3533
3534 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3535 %aq = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3536 %aq2 = bitcast i8** %aq to i8*
3537 call void %<a href="#i_va_copy">llvm.va_copy</a>(i8 *%aq2, i8* %ap2)
3538 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %aq2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3539
3540 ; Stop processing of arguments.
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3541 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %ap2)
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3542 ret i32 %tmp
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3543}
3544</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3545</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3546
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3547<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3548<div class="doc_subsubsection">
3549 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3550</div>
3551
3552
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3553<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3554<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3555<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3556<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3557<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3558<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3559href="#i_va_arg">va_arg</a></tt>.</p>
3560
3561<h5>Arguments:</h5>
3562
3563<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3564
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3565<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3566
3567<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3568macro available in C. In a target-dependent way, it initializes the
3569<tt>va_list</tt> element the argument points to, so that the next call to
3570<tt>va_arg</tt> will produce the first variable argument passed to the function.
3571Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3572last argument of the function, the compiler can figure that out.</p>
3573
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3574</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3575
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3576<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3577<div class="doc_subsubsection">
3578 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3579</div>
3580
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3581<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3582<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3583<pre> declare void %llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3584<h5>Overview:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3585
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3586<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
3587which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
3588or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3589
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3590<h5>Arguments:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3591
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3592<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3593
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3594<h5>Semantics:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3595
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3596<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]3597macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
3598Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
3599 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
3600with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3601
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3602</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3603
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3604<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3605<div class="doc_subsubsection">
3606 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3607</div>
3608
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3609<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3610
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3611<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3612
3613<pre>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3614 declare void %llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3615</pre>
3616
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3617<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3618
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3619<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3620the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3621
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3622<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3623
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3624<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]3625The 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]3626
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3627
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3628<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3629
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3630<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3631available in C. In a target-dependent way, it copies the source
3632<tt>va_list</tt> element into the destination list. This intrinsic is necessary
3633because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3634arbitrarily complex and require memory allocation, for example.</p>
3635
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3636</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3637
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3638<!-- ======================================================================= -->
3639<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3640 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3641</div>
3642
3643<div class="doc_text">
3644
3645<p>
3646LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3647Collection</a> requires the implementation and generation of these intrinsics.
3648These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
3649stack</a>, as well as garbage collector implementations that require <a
3650href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
3651Front-ends for type-safe garbage collected languages should generate these
3652intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3653href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3654</p>
3655</div>
3656
3657<!-- _______________________________________________________________________ -->
3658<div class="doc_subsubsection">
3659 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3660</div>
3661
3662<div class="doc_text">
3663
3664<h5>Syntax:</h5>
3665
3666<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3667 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3668</pre>
3669
3670<h5>Overview:</h5>
3671
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]3672<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]3673the code generator, and allows some metadata to be associated with it.</p>
3674
3675<h5>Arguments:</h5>
3676
3677<p>The first argument specifies the address of a stack object that contains the
3678root pointer. The second pointer (which must be either a constant or a global
3679value address) contains the meta-data to be associated with the root.</p>
3680
3681<h5>Semantics:</h5>
3682
3683<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3684location. At compile-time, the code generator generates information to allow
3685the runtime to find the pointer at GC safe points.
3686</p>
3687
3688</div>
3689
3690
3691<!-- _______________________________________________________________________ -->
3692<div class="doc_subsubsection">
3693 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
3694</div>
3695
3696<div class="doc_text">
3697
3698<h5>Syntax:</h5>
3699
3700<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3701 declare i8 * %llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3702</pre>
3703
3704<h5>Overview:</h5>
3705
3706<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3707locations, allowing garbage collector implementations that require read
3708barriers.</p>
3709
3710<h5>Arguments:</h5>
3711
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3712<p>The second argument is the address to read from, which should be an address
3713allocated from the garbage collector. The first object is a pointer to the
3714start of the referenced object, if needed by the language runtime (otherwise
3715null).</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3716
3717<h5>Semantics:</h5>
3718
3719<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3720instruction, but may be replaced with substantially more complex code by the
3721garbage collector runtime, as needed.</p>
3722
3723</div>
3724
3725
3726<!-- _______________________________________________________________________ -->
3727<div class="doc_subsubsection">
3728 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
3729</div>
3730
3731<div class="doc_text">
3732
3733<h5>Syntax:</h5>
3734
3735<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3736 declare void %llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3737</pre>
3738
3739<h5>Overview:</h5>
3740
3741<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3742locations, allowing garbage collector implementations that require write
3743barriers (such as generational or reference counting collectors).</p>
3744
3745<h5>Arguments:</h5>
3746
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3747<p>The first argument is the reference to store, the second is the start of the
3748object to store it to, and the third is the address of the field of Obj to
3749store to. If the runtime does not require a pointer to the object, Obj may be
3750null.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3751
3752<h5>Semantics:</h5>
3753
3754<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3755instruction, but may be replaced with substantially more complex code by the
3756garbage collector runtime, as needed.</p>
3757
3758</div>
3759
3760
3761
3762<!-- ======================================================================= -->
3763<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3764 <a name="int_codegen">Code Generator Intrinsics</a>
3765</div>
3766
3767<div class="doc_text">
3768<p>
3769These intrinsics are provided by LLVM to expose special features that may only
3770be implemented with code generator support.
3771</p>
3772
3773</div>
3774
3775<!-- _______________________________________________________________________ -->
3776<div class="doc_subsubsection">
3777 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
3778</div>
3779
3780<div class="doc_text">
3781
3782<h5>Syntax:</h5>
3783<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3784 declare i8 *%llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3785</pre>
3786
3787<h5>Overview:</h5>
3788
3789<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3790The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3791target-specific value indicating the return address of the current function
3792or one of its callers.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3793</p>
3794
3795<h5>Arguments:</h5>
3796
3797<p>
3798The argument to this intrinsic indicates which function to return the address
3799for. Zero indicates the calling function, one indicates its caller, etc. The
3800argument is <b>required</b> to be a constant integer value.
3801</p>
3802
3803<h5>Semantics:</h5>
3804
3805<p>
3806The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3807the return address of the specified call frame, or zero if it cannot be
3808identified. The value returned by this intrinsic is likely to be incorrect or 0
3809for arguments other than zero, so it should only be used for debugging purposes.
3810</p>
3811
3812<p>
3813Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3814aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3815source-language caller.
3816</p>
3817</div>
3818
3819
3820<!-- _______________________________________________________________________ -->
3821<div class="doc_subsubsection">
3822 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
3823</div>
3824
3825<div class="doc_text">
3826
3827<h5>Syntax:</h5>
3828<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3829 declare i8 *%llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3830</pre>
3831
3832<h5>Overview:</h5>
3833
3834<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3835The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3836target-specific frame pointer value for the specified stack frame.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3837</p>
3838
3839<h5>Arguments:</h5>
3840
3841<p>
3842The argument to this intrinsic indicates which function to return the frame
3843pointer for. Zero indicates the calling function, one indicates its caller,
3844etc. The argument is <b>required</b> to be a constant integer value.
3845</p>
3846
3847<h5>Semantics:</h5>
3848
3849<p>
3850The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3851the frame address of the specified call frame, or zero if it cannot be
3852identified. The value returned by this intrinsic is likely to be incorrect or 0
3853for arguments other than zero, so it should only be used for debugging purposes.
3854</p>
3855
3856<p>
3857Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3858aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3859source-language caller.
3860</p>
3861</div>
3862
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3863<!-- _______________________________________________________________________ -->
3864<div class="doc_subsubsection">
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3865 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
3866</div>
3867
3868<div class="doc_text">
3869
3870<h5>Syntax:</h5>
3871<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3872 declare i8 *%llvm.stacksave()
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3873</pre>
3874
3875<h5>Overview:</h5>
3876
3877<p>
3878The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
3879the function stack, for use with <a href="#i_stackrestore">
3880<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3881features like scoped automatic variable sized arrays in C99.
3882</p>
3883
3884<h5>Semantics:</h5>
3885
3886<p>
3887This intrinsic returns a opaque pointer value that can be passed to <a
3888href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
3889<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
3890<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
3891state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
3892practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
3893that were allocated after the <tt>llvm.stacksave</tt> was executed.
3894</p>
3895
3896</div>
3897
3898<!-- _______________________________________________________________________ -->
3899<div class="doc_subsubsection">
3900 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
3901</div>
3902
3903<div class="doc_text">
3904
3905<h5>Syntax:</h5>
3906<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3907 declare void %llvm.stackrestore(i8 * %ptr)
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3908</pre>
3909
3910<h5>Overview:</h5>
3911
3912<p>
3913The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
3914the function stack to the state it was in when the corresponding <a
3915href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
3916useful for implementing language features like scoped automatic variable sized
3917arrays in C99.
3918</p>
3919
3920<h5>Semantics:</h5>
3921
3922<p>
3923See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
3924</p>
3925
3926</div>
3927
3928
3929<!-- _______________________________________________________________________ -->
3930<div class="doc_subsubsection">
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3931 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
3932</div>
3933
3934<div class="doc_text">
3935
3936<h5>Syntax:</h5>
3937<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3938 declare void %llvm.prefetch(i8 * &lt;address&gt;,
3939 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3940</pre>
3941
3942<h5>Overview:</h5>
3943
3944
3945<p>
3946The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3947a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
3948no
3949effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]3950characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3951</p>
3952
3953<h5>Arguments:</h5>
3954
3955<p>
3956<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
3957determining if the fetch should be for a read (0) or write (1), and
3958<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]3959locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3960<tt>locality</tt> arguments must be constant integers.
3961</p>
3962
3963<h5>Semantics:</h5>
3964
3965<p>
3966This intrinsic does not modify the behavior of the program. In particular,
3967prefetches cannot trap and do not produce a value. On targets that support this
3968intrinsic, the prefetch can provide hints to the processor cache for better
3969performance.
3970</p>
3971
3972</div>
3973
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3974<!-- _______________________________________________________________________ -->
3975<div class="doc_subsubsection">
3976 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
3977</div>
3978
3979<div class="doc_text">
3980
3981<h5>Syntax:</h5>
3982<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3983 declare void %llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3984</pre>
3985
3986<h5>Overview:</h5>
3987
3988
3989<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3990The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
3991(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3992code to simulators and other tools. The method is target specific, but it is
3993expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3994The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnerd07c3f42005-11-15 06:07:55 +0000[diff] [blame]3995after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb3e7afd2006-03-24 07:16:10 +0000[diff] [blame]3996optimizations. The intended use is to be inserted after optimizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3997correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3998</p>
3999
4000<h5>Arguments:</h5>
4001
4002<p>
4003<tt>id</tt> is a numerical id identifying the marker.
4004</p>
4005
4006<h5>Semantics:</h5>
4007
4008<p>
4009This intrinsic does not modify the behavior of the program. Backends that do not
4010support this intrinisic may ignore it.
4011</p>
4012
4013</div>
4014
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4015<!-- _______________________________________________________________________ -->
4016<div class="doc_subsubsection">
4017 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4018</div>
4019
4020<div class="doc_text">
4021
4022<h5>Syntax:</h5>
4023<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4024 declare i64 %llvm.readcyclecounter( )
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4025</pre>
4026
4027<h5>Overview:</h5>
4028
4029
4030<p>
4031The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4032counter register (or similar low latency, high accuracy clocks) on those targets
4033that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4034As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4035should only be used for small timings.
4036</p>
4037
4038<h5>Semantics:</h5>
4039
4040<p>
4041When directly supported, reading the cycle counter should not modify any memory.
4042Implementations are allowed to either return a application specific value or a
4043system wide value. On backends without support, this is lowered to a constant 0.
4044</p>
4045
4046</div>
4047
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4048<!-- ======================================================================= -->
4049<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4050 <a name="int_libc">Standard C Library Intrinsics</a>
4051</div>
4052
4053<div class="doc_text">
4054<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4055LLVM provides intrinsics for a few important standard C library functions.
4056These intrinsics allow source-language front-ends to pass information about the
4057alignment of the pointer arguments to the code generator, providing opportunity
4058for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4059</p>
4060
4061</div>
4062
4063<!-- _______________________________________________________________________ -->
4064<div class="doc_subsubsection">
4065 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4066</div>
4067
4068<div class="doc_text">
4069
4070<h5>Syntax:</h5>
4071<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4072 declare void %llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4073 i32 &lt;len&gt;, i32 &lt;align&gt;)
4074 declare void %llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4075 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4076</pre>
4077
4078<h5>Overview:</h5>
4079
4080<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4081The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4082location to the destination location.
4083</p>
4084
4085<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4086Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4087intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4088</p>
4089
4090<h5>Arguments:</h5>
4091
4092<p>
4093The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4094the source. The third argument is an integer argument
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4095specifying the number of bytes to copy, and the fourth argument is the alignment
4096of the source and destination locations.
4097</p>
4098
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4099<p>
4100If 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]4101the caller guarantees that both the source and destination pointers are aligned
4102to that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4103</p>
4104
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4105<h5>Semantics:</h5>
4106
4107<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4108The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4109location to the destination location, which are not allowed to overlap. It
4110copies "len" bytes of memory over. If the argument is known to be aligned to
4111some boundary, this can be specified as the fourth argument, otherwise it should
4112be set to 0 or 1.
4113</p>
4114</div>
4115
4116
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4117<!-- _______________________________________________________________________ -->
4118<div class="doc_subsubsection">
4119 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4120</div>
4121
4122<div class="doc_text">
4123
4124<h5>Syntax:</h5>
4125<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4126 declare void %llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4127 i32 &lt;len&gt;, i32 &lt;align&gt;)
4128 declare void %llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4129 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4130</pre>
4131
4132<h5>Overview:</h5>
4133
4134<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4135The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4136location to the destination location. It is similar to the
4137'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4138</p>
4139
4140<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4141Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4142intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4143</p>
4144
4145<h5>Arguments:</h5>
4146
4147<p>
4148The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4149the source. The third argument is an integer argument
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4150specifying the number of bytes to copy, and the fourth argument is the alignment
4151of the source and destination locations.
4152</p>
4153
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4154<p>
4155If 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]4156the caller guarantees that the source and destination pointers are aligned to
4157that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4158</p>
4159
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4160<h5>Semantics:</h5>
4161
4162<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4163The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4164location to the destination location, which may overlap. It
4165copies "len" bytes of memory over. If the argument is known to be aligned to
4166some boundary, this can be specified as the fourth argument, otherwise it should
4167be set to 0 or 1.
4168</p>
4169</div>
4170
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4171
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4172<!-- _______________________________________________________________________ -->
4173<div class="doc_subsubsection">
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4174 <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4175</div>
4176
4177<div class="doc_text">
4178
4179<h5>Syntax:</h5>
4180<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4181 declare void %llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4182 i32 &lt;len&gt;, i32 &lt;align&gt;)
4183 declare void %llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4184 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4185</pre>
4186
4187<h5>Overview:</h5>
4188
4189<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4190The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4191byte value.
4192</p>
4193
4194<p>
4195Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4196does not return a value, and takes an extra alignment argument.
4197</p>
4198
4199<h5>Arguments:</h5>
4200
4201<p>
4202The first argument is a pointer to the destination to fill, the second is the
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4203byte value to fill it with, the third argument is an integer
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4204argument specifying the number of bytes to fill, and the fourth argument is the
4205known alignment of destination location.
4206</p>
4207
4208<p>
4209If 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]4210the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4211</p>
4212
4213<h5>Semantics:</h5>
4214
4215<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4216The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4217the
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4218destination location. If the argument is known to be aligned to some boundary,
4219this can be specified as the fourth argument, otherwise it should be set to 0 or
42201.
4221</p>
4222</div>
4223
4224
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4225<!-- _______________________________________________________________________ -->
4226<div class="doc_subsubsection">
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4227 <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4228</div>
4229
4230<div class="doc_text">
4231
4232<h5>Syntax:</h5>
4233<pre>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4234 declare float %llvm.sqrt.f32(float %Val)
4235 declare double %llvm.sqrt.f64(double %Val)
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4236</pre>
4237
4238<h5>Overview:</h5>
4239
4240<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4241The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4242returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4243<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4244negative numbers (which allows for better optimization).
4245</p>
4246
4247<h5>Arguments:</h5>
4248
4249<p>
4250The argument and return value are floating point numbers of the same type.
4251</p>
4252
4253<h5>Semantics:</h5>
4254
4255<p>
4256This function returns the sqrt of the specified operand if it is a positive
4257floating point number.
4258</p>
4259</div>
4260
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4261<!-- _______________________________________________________________________ -->
4262<div class="doc_subsubsection">
4263 <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4264</div>
4265
4266<div class="doc_text">
4267
4268<h5>Syntax:</h5>
4269<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4270 declare float %llvm.powi.f32(float %Val, i32 %power)
4271 declare double %llvm.powi.f64(double %Val, i32 %power)
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4272</pre>
4273
4274<h5>Overview:</h5>
4275
4276<p>
4277The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4278specified (positive or negative) power. The order of evaluation of
4279multiplications is not defined.
4280</p>
4281
4282<h5>Arguments:</h5>
4283
4284<p>
4285The second argument is an integer power, and the first is a value to raise to
4286that power.
4287</p>
4288
4289<h5>Semantics:</h5>
4290
4291<p>
4292This function returns the first value raised to the second power with an
4293unspecified sequence of rounding operations.</p>
4294</div>
4295
4296
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4297<!-- ======================================================================= -->
4298<div class="doc_subsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4299 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4300</div>
4301
4302<div class="doc_text">
4303<p>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4304LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4305These allow efficient code generation for some algorithms.
4306</p>
4307
4308</div>
4309
4310<!-- _______________________________________________________________________ -->
4311<div class="doc_subsubsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4312 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4313</div>
4314
4315<div class="doc_text">
4316
4317<h5>Syntax:</h5>
4318<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4319 declare i16 %llvm.bswap.i16(i16 &lt;id&gt;)
4320 declare i32 %llvm.bswap.i32(i32 &lt;id&gt;)
4321 declare i64 %llvm.bswap.i64(i64 &lt;id&gt;)
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4322</pre>
4323
4324<h5>Overview:</h5>
4325
4326<p>
4327The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
432864 bit quantity. These are useful for performing operations on data that is not
4329in the target's native byte order.
4330</p>
4331
4332<h5>Semantics:</h5>
4333
4334<p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4335The <tt>llvm.bswap.16</tt> intrinsic returns an i16 value that has the high
4336and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4337intrinsic returns an i32 value that has the four bytes of the input i32
4338swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
4339i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt>
4340intrinsic extends this concept to 64 bits.
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4341</p>
4342
4343</div>
4344
4345<!-- _______________________________________________________________________ -->
4346<div class="doc_subsubsection">
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4347 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4348</div>
4349
4350<div class="doc_text">
4351
4352<h5>Syntax:</h5>
4353<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4354 declare i8 %llvm.ctpop.i8 (i8 &lt;src&gt;)
4355 declare i16 %llvm.ctpop.i16(i16 &lt;src&gt;)
4356 declare i32 %llvm.ctpop.i32(i32 &lt;src&gt;)
4357 declare i64 %llvm.ctpop.i64(i64 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4358</pre>
4359
4360<h5>Overview:</h5>
4361
4362<p>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4363The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4364value.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4365</p>
4366
4367<h5>Arguments:</h5>
4368
4369<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4370The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4371integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4372</p>
4373
4374<h5>Semantics:</h5>
4375
4376<p>
4377The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4378</p>
4379</div>
4380
4381<!-- _______________________________________________________________________ -->
4382<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4383 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4384</div>
4385
4386<div class="doc_text">
4387
4388<h5>Syntax:</h5>
4389<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4390 declare i8 %llvm.ctlz.i8 (i8 &lt;src&gt;)
4391 declare i16 %llvm.ctlz.i16(i16 &lt;src&gt;)
4392 declare i32 %llvm.ctlz.i32(i32 &lt;src&gt;)
4393 declare i64 %llvm.ctlz.i64(i64 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4394</pre>
4395
4396<h5>Overview:</h5>
4397
4398<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4399The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4400leading zeros in a variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4401</p>
4402
4403<h5>Arguments:</h5>
4404
4405<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4406The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4407integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4408</p>
4409
4410<h5>Semantics:</h5>
4411
4412<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4413The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4414in 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]4415of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4416</p>
4417</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4418
4419
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4420
4421<!-- _______________________________________________________________________ -->
4422<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4423 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4424</div>
4425
4426<div class="doc_text">
4427
4428<h5>Syntax:</h5>
4429<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4430 declare i8 %llvm.cttz.i8 (i8 &lt;src&gt;)
4431 declare i16 %llvm.cttz.i16(i16 &lt;src&gt;)
4432 declare i32 %llvm.cttz.i32(i32 &lt;src&gt;)
4433 declare i64 %llvm.cttz.i64(i64 &lt;src&gt;)
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4434</pre>
4435
4436<h5>Overview:</h5>
4437
4438<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4439The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4440trailing zeros.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4441</p>
4442
4443<h5>Arguments:</h5>
4444
4445<p>
4446The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4447integer type. The return type must match the argument type.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4448</p>
4449
4450<h5>Semantics:</h5>
4451
4452<p>
4453The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4454in a variable. If the src == 0 then the result is the size in bits of the type
4455of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4456</p>
4457</div>
4458
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4459<!-- ======================================================================= -->
4460<div class="doc_subsection">
4461 <a name="int_debugger">Debugger Intrinsics</a>
4462</div>
4463
4464<div class="doc_text">
4465<p>
4466The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4467are described in the <a
4468href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4469Debugging</a> document.
4470</p>
4471</div>
4472
4473
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4474<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4475<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4476<address>
4477 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4478 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
4479 <a href="http://validator.w3.org/check/referer"><img
4480 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4481
4482 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]4483 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4484 Last modified: $Date$
4485</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]4486</body>
4487</html>