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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 8e11bf8508613f6eb2b72d46f65ff28dc69f9204 / . / 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>
Reid Spencer8e11bf82007-02-02 13:57:07 +0000[diff] [blame^]92 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
93 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
94 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]95 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]96 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]97 <li><a href="#i_xor">'<tt>xor</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
533 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
534
535 <dd>This calling convention attempts to make calls as fast as possible
536 (e.g. by passing things in registers). This calling convention allows the
537 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]538 without having to conform to an externally specified ABI. Implementations of
539 this convention should allow arbitrary tail call optimization to be supported.
540 This calling convention does not support varargs and requires the prototype of
541 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]542 </dd>
543
544 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
545
546 <dd>This calling convention attempts to make code in the caller as efficient
547 as possible under the assumption that the call is not commonly executed. As
548 such, these calls often preserve all registers so that the call does not break
549 any live ranges in the caller side. This calling convention does not support
550 varargs and requires the prototype of all callees to exactly match the
551 prototype of the function definition.
552 </dd>
553
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]554 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]555
556 <dd>Any calling convention may be specified by number, allowing
557 target-specific calling conventions to be used. Target specific calling
558 conventions start at 64.
559 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]560</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]561
562<p>More calling conventions can be added/defined on an as-needed basis, to
563support pascal conventions or any other well-known target-independent
564convention.</p>
565
566</div>
567
568<!-- ======================================================================= -->
569<div class="doc_subsection">
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]570 <a name="visibility">Visibility Styles</a>
571</div>
572
573<div class="doc_text">
574
575<p>
576All Global Variables and Functions have one of the following visibility styles:
577</p>
578
579<dl>
580 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
581
582 <dd>On ELF, default visibility means that the declaration is visible to other
583 modules and, in shared libraries, means that the declared entity may be
584 overridden. On Darwin, default visibility means that the declaration is
585 visible to other modules. Default visibility corresponds to "external
586 linkage" in the language.
587 </dd>
588
589 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
590
591 <dd>Two declarations of an object with hidden visibility refer to the same
592 object if they are in the same shared object. Usually, hidden visibility
593 indicates that the symbol will not be placed into the dynamic symbol table,
594 so no other module (executable or shared library) can reference it
595 directly.
596 </dd>
597
598</dl>
599
600</div>
601
602<!-- ======================================================================= -->
603<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]604 <a name="globalvars">Global Variables</a>
605</div>
606
607<div class="doc_text">
608
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]609<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]610instead of run-time. Global variables may optionally be initialized, may have
611an explicit section to be placed in, and may
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]612have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]613variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]614contents of the variable will <b>never</b> be modified (enabling better
615optimization, allowing the global data to be placed in the read-only section of
616an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]617cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]618
619<p>
620LLVM explicitly allows <em>declarations</em> of global variables to be marked
621constant, even if the final definition of the global is not. This capability
622can be used to enable slightly better optimization of the program, but requires
623the language definition to guarantee that optimizations based on the
624'constantness' are valid for the translation units that do not include the
625definition.
626</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]627
628<p>As SSA values, global variables define pointer values that are in
629scope (i.e. they dominate) all basic blocks in the program. Global
630variables always define a pointer to their "content" type because they
631describe a region of memory, and all memory objects in LLVM are
632accessed through pointers.</p>
633
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]634<p>LLVM allows an explicit section to be specified for globals. If the target
635supports it, it will emit globals to the section specified.</p>
636
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]637<p>An explicit alignment may be specified for a global. If not present, or if
638the alignment is set to zero, the alignment of the global is set by the target
639to whatever it feels convenient. If an explicit alignment is specified, the
640global is forced to have at least that much alignment. All alignments must be
641a power of 2.</p>
642
Chris Lattner68027ea2007-01-14 00:27:09 +0000[diff] [blame]643<p>For example, the following defines a global with an initializer, section,
644 and alignment:</p>
645
646<pre>
647 %G = constant float 1.0, section "foo", align 4
648</pre>
649
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]650</div>
651
652
653<!-- ======================================================================= -->
654<div class="doc_subsection">
655 <a name="functionstructure">Functions</a>
656</div>
657
658<div class="doc_text">
659
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]660<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
661an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]662<a href="#visibility">visibility style</a>, an optional
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]663<a href="#callingconv">calling convention</a>, a return type, an optional
664<a href="#paramattrs">parameter attribute</a> for the return type, a function
665name, a (possibly empty) argument list (each with optional
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame]666<a href="#paramattrs">parameter attributes</a>), an optional section, an
667optional alignment, an opening curly brace, a list of basic blocks, and a
668closing curly brace.
669
670LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
671optional <a href="#linkage">linkage type</a>, an optional
672<a href="#visibility">visibility style</a>, an optional
673<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]674<a href="#paramattrs">parameter attribute</a> for the return type, a function
675name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]676
677<p>A function definition contains a list of basic blocks, forming the CFG for
678the function. Each basic block may optionally start with a label (giving the
679basic block a symbol table entry), contains a list of instructions, and ends
680with a <a href="#terminators">terminator</a> instruction (such as a branch or
681function return).</p>
682
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]683<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]684executed on entrance to the function, and it is not allowed to have predecessor
685basic blocks (i.e. there can not be any branches to the entry block of a
686function). Because the block can have no predecessors, it also cannot have any
687<a href="#i_phi">PHI nodes</a>.</p>
688
689<p>LLVM functions are identified by their name and type signature. Hence, two
690functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]691considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]692appropriately.</p>
693
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]694<p>LLVM allows an explicit section to be specified for functions. If the target
695supports it, it will emit functions to the section specified.</p>
696
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]697<p>An explicit alignment may be specified for a function. If not present, or if
698the alignment is set to zero, the alignment of the function is set by the target
699to whatever it feels convenient. If an explicit alignment is specified, the
700function is forced to have at least that much alignment. All alignments must be
701a power of 2.</p>
702
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]703</div>
704
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]705<!-- ======================================================================= -->
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]706<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
707<div class="doc_text">
708 <p>The return type and each parameter of a function type may have a set of
709 <i>parameter attributes</i> associated with them. Parameter attributes are
710 used to communicate additional information about the result or parameters of
711 a function. Parameter attributes are considered to be part of the function
712 type so two functions types that differ only by the parameter attributes
713 are different function types.</p>
714
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]715 <p>Parameter attributes are simple keywords that follow the type specified. If
716 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]717 example:</p><pre>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]718 %someFunc = i16 (i8 sext %someParam) zext
719 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]720 <p>Note that the two function types above are unique because the parameter has
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]721 a different attribute (sext in the first one, zext in the second). Also note
722 that the attribute for the function result (zext) comes immediately after the
723 argument list.</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]724
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]725 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]726 <dl>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]727 <dt><tt>zext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]728 <dd>This indicates that the parameter should be zero extended just before
729 a call to this function.</dd>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]730 <dt><tt>sext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]731 <dd>This indicates that the parameter should be sign extended just before
732 a call to this function.</dd>
Anton Korobeynikov34d6dea2007-01-28 14:30:45 +0000[diff] [blame]733 <dt><tt>inreg</tt></dt>
734 <dd>This indicates that the parameter should be placed in register (if
Anton Korobeynikov66a8c8c2007-01-28 15:27:21 +0000[diff] [blame]735 possible) during assembling function call. Support for this attribute is
736 target-specific</dd>
Anton Korobeynikov34d6dea2007-01-28 14:30:45 +0000[diff] [blame]737 <dt><tt>sret</tt></dt>
Anton Korobeynikov66a8c8c2007-01-28 15:27:21 +0000[diff] [blame]738 <dd>This indicates that the parameter specifies the address of a structure
739 that is the return value of the function in the source program.
740 </dd>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]741 </dl>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]742
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]743</div>
744
745<!-- ======================================================================= -->
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]746<div class="doc_subsection">
Chris Lattner1eeeb0c2006-04-08 04:40:53 +0000[diff] [blame]747 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]748</div>
749
750<div class="doc_text">
751<p>
752Modules may contain "module-level inline asm" blocks, which corresponds to the
753GCC "file scope inline asm" blocks. These blocks are internally concatenated by
754LLVM and treated as a single unit, but may be separated in the .ll file if
755desired. The syntax is very simple:
756</p>
757
758<div class="doc_code"><pre>
Chris Lattner52599e12006-01-24 00:37:20 +0000[diff] [blame]759 module asm "inline asm code goes here"
760 module asm "more can go here"
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]761</pre></div>
762
763<p>The strings can contain any character by escaping non-printable characters.
764 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
765 for the number.
766</p>
767
768<p>
769 The inline asm code is simply printed to the machine code .s file when
770 assembly code is generated.
771</p>
772</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]773
774
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]775<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]776<div class="doc_section"> <a name="typesystem">Type System</a> </div>
777<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]778
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]779<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]780
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]781<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]782intermediate representation. Being typed enables a number of
783optimizations to be performed on the IR directly, without having to do
784extra analyses on the side before the transformation. A strong type
785system makes it easier to read the generated code and enables novel
786analyses and transformations that are not feasible to perform on normal
787three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]788
789</div>
790
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]791<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]792<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]793<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]794<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]795system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]796
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]797<table class="layout">
798 <tr class="layout">
799 <td class="left">
800 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]801 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]802 <tr><th>Type</th><th>Description</th></tr>
803 <tr><td><tt>void</tt></td><td>No value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]804 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
805 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]806 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]807 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]808 </tbody>
809 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]810 </td>
811 <td class="right">
812 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]813 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]814 <tr><th>Type</th><th>Description</th></tr>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]815 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]816 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
817 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]818 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]819 </tbody>
820 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]821 </td>
822 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]823</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]824</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]825
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]826<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]827<div class="doc_subsubsection"> <a name="t_classifications">Type
828Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]829<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]830<p>These different primitive types fall into a few useful
831classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]832
833<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]834 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]835 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]836 <tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]837 <td><a name="t_integer">integer</a></td>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]838 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]839 </tr>
840 <tr>
841 <td><a name="t_floating">floating point</a></td>
842 <td><tt>float, double</tt></td>
843 </tr>
844 <tr>
845 <td><a name="t_firstclass">first class</a></td>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]846 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]847 <a href="#t_pointer">pointer</a>,<a href="#t_packed">packed</a></tt>
848 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]849 </tr>
850 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]851</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]852
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]853<p>The <a href="#t_firstclass">first class</a> types are perhaps the
854most important. Values of these types are the only ones which can be
855produced by instructions, passed as arguments, or used as operands to
856instructions. This means that all structures and arrays must be
857manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]858</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]859
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]860<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]861<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]862
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]863<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]864
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]865<p>The real power in LLVM comes from the derived types in the system.
866This is what allows a programmer to represent arrays, functions,
867pointers, and other useful types. Note that these derived types may be
868recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]869
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]870</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]871
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]872<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]873<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]874
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]875<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]876
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]877<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]878
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]879<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]880sequentially in memory. The array type requires a size (number of
881elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]882
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]883<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]884
885<pre>
886 [&lt;# elements&gt; x &lt;elementtype&gt;]
887</pre>
888
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]889<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]890be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]891
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]892<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]893<table class="layout">
894 <tr class="layout">
895 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]896 <tt>[40 x i32 ]</tt><br/>
897 <tt>[41 x i32 ]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]898 <tt>[40 x i8]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]899 </td>
900 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]901 Array of 40 32-bit integer values.<br/>
902 Array of 41 32-bit integer values.<br/>
903 Array of 40 8-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]904 </td>
905 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]906</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]907<p>Here are some examples of multidimensional arrays:</p>
908<table class="layout">
909 <tr class="layout">
910 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]911 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]912 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]913 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]914 </td>
915 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]916 3x4 array of 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]917 12x10 array of single precision floating point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]918 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]919 </td>
920 </tr>
921</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]922
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]923<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
924length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]925LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
926As a special case, however, zero length arrays are recognized to be variable
927length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]928type "{ i32, [0 x float]}", for example.</p>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]929
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]930</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]931
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]932<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]933<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]934<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]935<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]936<p>The function type can be thought of as a function signature. It
937consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]938Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]939(which are structures of pointers to functions), for indirect function
940calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]941<p>
942The return type of a function type cannot be an aggregate type.
943</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]944<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]945<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]946<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]947specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]948which indicates that the function takes a variable number of arguments.
949Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]950 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]951<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]952<table class="layout">
953 <tr class="layout">
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]954 <td class="left"><tt>i32 (i32)</tt></td>
955 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]956 </td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]957 </tr><tr class="layout">
Reid Spencer7bf214d2007-01-15 18:28:34 +0000[diff] [blame]958 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencerf17a0b72006-12-31 07:20:23 +0000[diff] [blame]959 </tt></td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]960 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
961 an <tt>i16</tt> that should be sign extended and a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]962 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]963 <tt>float</tt>.
964 </td>
965 </tr><tr class="layout">
966 <td class="left"><tt>i32 (i8*, ...)</tt></td>
967 <td class="left">A vararg function that takes at least one
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]968 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]969 which returns an integer. This is the signature for <tt>printf</tt> in
970 LLVM.
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]971 </td>
972 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]973</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]974
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]975</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]976<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]977<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]978<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]979<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]980<p>The structure type is used to represent a collection of data members
981together in memory. The packing of the field types is defined to match
982the ABI of the underlying processor. The elements of a structure may
983be any type that has a size.</p>
984<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
985and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
986field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
987instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]988<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]989<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]990<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]991<table class="layout">
992 <tr class="layout">
993 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]994 <tt>{ i32, i32, i32 }</tt><br/>
995 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]996 </td>
997 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]998 a triple of three <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]999 A pair, where the first element is a <tt>float</tt> and the second element
1000 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]1001 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1002 </td>
1003 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1004</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1005</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1006
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1007<!-- _______________________________________________________________________ -->
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1008<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1009</div>
1010<div class="doc_text">
1011<h5>Overview:</h5>
1012<p>The packed structure type is used to represent a collection of data members
1013together in memory. There is no padding between fields. Further, the alignment
1014of a packed structure is 1 byte. The elements of a packed structure may
1015be any type that has a size.</p>
1016<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1017and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1018field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1019instruction.</p>
1020<h5>Syntax:</h5>
1021<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1022<h5>Examples:</h5>
1023<table class="layout">
1024 <tr class="layout">
1025 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1026 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1027 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1028 </td>
1029 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1030 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1031 A pair, where the first element is a <tt>float</tt> and the second element
1032 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]1033 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1034 </td>
1035 </tr>
1036</table>
1037</div>
1038
1039<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1040<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1041<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1042<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1043<p>As in many languages, the pointer type represents a pointer or
1044reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1045<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1046<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1047<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1048<table class="layout">
1049 <tr class="layout">
1050 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1051 <tt>[4x i32]*</tt><br/>
1052 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1053 </td>
1054 <td class="left">
1055 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]1056 four <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1057 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1058 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1059 <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1060 </td>
1061 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1062</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1063</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1064
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1065<!-- _______________________________________________________________________ -->
1066<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1067<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1068
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1069<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1070
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1071<p>A packed type is a simple derived type that represents a vector
1072of elements. Packed types are used when multiple primitive data
1073are operated in parallel using a single instruction (SIMD).
1074A packed type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]1075elements) and an underlying primitive data type. Vectors must have a power
1076of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1077considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1078
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1079<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1080
1081<pre>
1082 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1083</pre>
1084
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1085<p>The number of elements is a constant integer value; elementtype may
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1086be any integer or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1087
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1088<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1089
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1090<table class="layout">
1091 <tr class="layout">
1092 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1093 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1094 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1095 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1096 </td>
1097 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1098 Packed vector of 4 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1099 Packed vector of 8 floating-point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1100 Packed vector of 2 64-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1101 </td>
1102 </tr>
1103</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1104</div>
1105
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1106<!-- _______________________________________________________________________ -->
1107<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1108<div class="doc_text">
1109
1110<h5>Overview:</h5>
1111
1112<p>Opaque types are used to represent unknown types in the system. This
1113corresponds (for example) to the C notion of a foward declared structure type.
1114In LLVM, opaque types can eventually be resolved to any type (not just a
1115structure type).</p>
1116
1117<h5>Syntax:</h5>
1118
1119<pre>
1120 opaque
1121</pre>
1122
1123<h5>Examples:</h5>
1124
1125<table class="layout">
1126 <tr class="layout">
1127 <td class="left">
1128 <tt>opaque</tt>
1129 </td>
1130 <td class="left">
1131 An opaque type.<br/>
1132 </td>
1133 </tr>
1134</table>
1135</div>
1136
1137
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1138<!-- *********************************************************************** -->
1139<div class="doc_section"> <a name="constants">Constants</a> </div>
1140<!-- *********************************************************************** -->
1141
1142<div class="doc_text">
1143
1144<p>LLVM has several different basic types of constants. This section describes
1145them all and their syntax.</p>
1146
1147</div>
1148
1149<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1150<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1151
1152<div class="doc_text">
1153
1154<dl>
1155 <dt><b>Boolean constants</b></dt>
1156
1157 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1158 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1159 </dd>
1160
1161 <dt><b>Integer constants</b></dt>
1162
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1163 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1164 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1165 integer types.
1166 </dd>
1167
1168 <dt><b>Floating point constants</b></dt>
1169
1170 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1171 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1172 notation (see below). Floating point constants must have a <a
1173 href="#t_floating">floating point</a> type. </dd>
1174
1175 <dt><b>Null pointer constants</b></dt>
1176
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1177 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1178 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1179
1180</dl>
1181
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1182<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1183of floating point constants. For example, the form '<tt>double
11840x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
11854.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1186(and the only time that they are generated by the disassembler) is when a
1187floating point constant must be emitted but it cannot be represented as a
1188decimal floating point number. For example, NaN's, infinities, and other
1189special values are represented in their IEEE hexadecimal format so that
1190assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1191
1192</div>
1193
1194<!-- ======================================================================= -->
1195<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1196</div>
1197
1198<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1199<p>Aggregate constants arise from aggregation of simple constants
1200and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1201
1202<dl>
1203 <dt><b>Structure constants</b></dt>
1204
1205 <dd>Structure constants are represented with notation similar to structure
1206 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1207 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1208 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]1209 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1210 types of elements must match those specified by the type.
1211 </dd>
1212
1213 <dt><b>Array constants</b></dt>
1214
1215 <dd>Array constants are represented with notation similar to array type
1216 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1217 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1218 constants must have <a href="#t_array">array type</a>, and the number and
1219 types of elements must match those specified by the type.
1220 </dd>
1221
1222 <dt><b>Packed constants</b></dt>
1223
1224 <dd>Packed constants are represented with notation similar to packed type
1225 definitions (a comma separated list of elements, surrounded by
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1226 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1227 i32 11, i32 74, i32 100 &gt;</tt>". Packed constants must have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1228 href="#t_packed">packed type</a>, and the number and types of elements must
1229 match those specified by the type.
1230 </dd>
1231
1232 <dt><b>Zero initialization</b></dt>
1233
1234 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1235 value to zero of <em>any</em> type, including scalar and aggregate types.
1236 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]1237 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1238 initializers.
1239 </dd>
1240</dl>
1241
1242</div>
1243
1244<!-- ======================================================================= -->
1245<div class="doc_subsection">
1246 <a name="globalconstants">Global Variable and Function Addresses</a>
1247</div>
1248
1249<div class="doc_text">
1250
1251<p>The addresses of <a href="#globalvars">global variables</a> and <a
1252href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1253constants. These constants are explicitly referenced when the <a
1254href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1255href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1256file:</p>
1257
1258<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1259 %X = global i32 17
1260 %Y = global i32 42
1261 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1262</pre>
1263
1264</div>
1265
1266<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1267<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1268<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1269 <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]1270 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1271 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1272
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1273 <p>Undefined values indicate to the compiler that the program is well defined
1274 no matter what value is used, giving the compiler more freedom to optimize.
1275 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1276</div>
1277
1278<!-- ======================================================================= -->
1279<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1280</div>
1281
1282<div class="doc_text">
1283
1284<p>Constant expressions are used to allow expressions involving other constants
1285to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1286href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1287that does not have side effects (e.g. load and call are not supported). The
1288following is the syntax for constant expressions:</p>
1289
1290<dl>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1291 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1292 <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]1293 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1294
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1295 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1296 <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]1297 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]1298
1299 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1300 <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]1301 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]1302
1303 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1304 <dd>Truncate a floating point constant to another floating point type. The
1305 size of CST must be larger than the size of TYPE. Both types must be
1306 floating point.</dd>
1307
1308 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1309 <dd>Floating point extend a constant to another type. The size of CST must be
1310 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1311
1312 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1313 <dd>Convert a floating point constant to the corresponding unsigned integer
1314 constant. TYPE must be an integer type. CST must be floating point. If the
1315 value won't fit in the integer type, the results are undefined.</dd>
1316
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1317 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1318 <dd>Convert a floating point constant to the corresponding signed integer
1319 constant. TYPE must be an integer type. CST must be floating point. If the
1320 value won't fit in the integer type, the results are undefined.</dd>
1321
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1322 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1323 <dd>Convert an unsigned integer constant to the corresponding floating point
1324 constant. TYPE must be floating point. CST must be of integer type. If the
1325 value won't fit in the floating point type, the results are undefined.</dd>
1326
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1327 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1328 <dd>Convert a signed integer constant to the corresponding floating point
1329 constant. TYPE must be floating point. CST must be of integer type. If the
1330 value won't fit in the floating point type, the results are undefined.</dd>
1331
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1332 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1333 <dd>Convert a pointer typed constant to the corresponding integer constant
1334 TYPE must be an integer type. CST must be of pointer type. The CST value is
1335 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1336
1337 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1338 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1339 pointer type. CST must be of integer type. The CST value is zero extended,
1340 truncated, or unchanged to make it fit in a pointer size. This one is
1341 <i>really</i> dangerous!</dd>
1342
1343 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1344 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1345 identical (same number of bits). The conversion is done as if the CST value
1346 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]1347 with this operator, just the type. This can be used for conversion of
1348 packed types to any other type, as long as they have the same bit width. For
1349 pointers it is only valid to cast to another pointer type.
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1350 </dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1351
1352 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1353
1354 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1355 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1356 instruction, the index list may have zero or more indexes, which are required
1357 to make sense for the type of "CSTPTR".</dd>
1358
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1359 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1360
1361 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1362 constants.</dd>
1363
1364 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1365 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1366
1367 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1368 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1369
1370 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1371
1372 <dd>Perform the <a href="#i_extractelement">extractelement
1373 operation</a> on constants.
1374
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1375 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1376
1377 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1378 operation</a> on constants.</dd>
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1379
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1380
1381 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1382
1383 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1384 operation</a> on constants.</dd>
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1385
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1386 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1387
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1388 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1389 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1390 binary</a> operations. The constraints on operands are the same as those for
1391 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1392 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1393</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1394</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1395
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1396<!-- *********************************************************************** -->
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1397<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1398<!-- *********************************************************************** -->
1399
1400<!-- ======================================================================= -->
1401<div class="doc_subsection">
1402<a name="inlineasm">Inline Assembler Expressions</a>
1403</div>
1404
1405<div class="doc_text">
1406
1407<p>
1408LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1409Module-Level Inline Assembly</a>) through the use of a special value. This
1410value represents the inline assembler as a string (containing the instructions
1411to emit), a list of operand constraints (stored as a string), and a flag that
1412indicates whether or not the inline asm expression has side effects. An example
1413inline assembler expression is:
1414</p>
1415
1416<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1417 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1418</pre>
1419
1420<p>
1421Inline assembler expressions may <b>only</b> be used as the callee operand of
1422a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1423</p>
1424
1425<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1426 %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]1427</pre>
1428
1429<p>
1430Inline asms with side effects not visible in the constraint list must be marked
1431as having side effects. This is done through the use of the
1432'<tt>sideeffect</tt>' keyword, like so:
1433</p>
1434
1435<pre>
1436 call void asm sideeffect "eieio", ""()
1437</pre>
1438
1439<p>TODO: The format of the asm and constraints string still need to be
1440documented here. Constraints on what can be done (e.g. duplication, moving, etc
1441need to be documented).
1442</p>
1443
1444</div>
1445
1446<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1447<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1448<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1449
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1450<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1451
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1452<p>The LLVM instruction set consists of several different
1453classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1454instructions</a>, <a href="#binaryops">binary instructions</a>,
1455<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1456 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1457instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1458
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1459</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1460
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1461<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1462<div class="doc_subsection"> <a name="terminators">Terminator
1463Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1464
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1465<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1466
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1467<p>As mentioned <a href="#functionstructure">previously</a>, every
1468basic block in a program ends with a "Terminator" instruction, which
1469indicates which block should be executed after the current block is
1470finished. These terminator instructions typically yield a '<tt>void</tt>'
1471value: they produce control flow, not values (the one exception being
1472the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1473<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1474 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1475instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1476the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1477 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1478 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1479
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1480</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1481
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1482<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1483<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1484Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1485<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1486<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1487<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]1488 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1489</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1490<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1491<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1492value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1493<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1494returns a value and then causes control flow, and one that just causes
1495control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1496<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1497<p>The '<tt>ret</tt>' instruction may return any '<a
1498 href="#t_firstclass">first class</a>' type. Notice that a function is
1499not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1500instruction inside of the function that returns a value that does not
1501match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1502<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1503<p>When the '<tt>ret</tt>' instruction is executed, control flow
1504returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1505 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1506the instruction after the call. If the caller was an "<a
1507 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1508at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1509returns a value, that value shall set the call or invoke instruction's
1510return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1511<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1512<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1513 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1514</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1515</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1516<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1517<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1518<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1519<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1520<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]1521</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1522<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1523<p>The '<tt>br</tt>' instruction is used to cause control flow to
1524transfer to a different basic block in the current function. There are
1525two forms of this instruction, corresponding to a conditional branch
1526and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1527<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1528<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1529single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1530unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1531value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1532<h5>Semantics:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1533<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1534argument is evaluated. If the value is <tt>true</tt>, control flows
1535to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1536control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1537<h5>Example:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1538<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]1539 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]1540</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1541<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1542<div class="doc_subsubsection">
1543 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1544</div>
1545
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1546<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1547<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1548
1549<pre>
1550 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1551</pre>
1552
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1553<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1554
1555<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1556several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1557instruction, allowing a branch to occur to one of many possible
1558destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1559
1560
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1561<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1562
1563<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1564comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1565an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1566table is not allowed to contain duplicate constant entries.</p>
1567
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1568<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1569
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1570<p>The <tt>switch</tt> instruction specifies a table of values and
1571destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1572table is searched for the given value. If the value is found, control flow is
1573transfered to the corresponding destination; otherwise, control flow is
1574transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1575
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1576<h5>Implementation:</h5>
1577
1578<p>Depending on properties of the target machine and the particular
1579<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1580ways. For example, it could be generated as a series of chained conditional
1581branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1582
1583<h5>Example:</h5>
1584
1585<pre>
1586 <i>; Emulate a conditional br instruction</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1587 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1588 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1589
1590 <i>; Emulate an unconditional br instruction</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1591 switch i32 0, label %dest [ ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1592
1593 <i>; Implement a jump table:</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1594 switch i32 %val, label %otherwise [ i32 0, label %onzero
1595 i32 1, label %onone
1596 i32 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1597</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1598</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1599
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1600<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1601<div class="doc_subsubsection">
1602 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1603</div>
1604
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1605<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1606
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1607<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1608
1609<pre>
1610 &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]1611 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1612</pre>
1613
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1614<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1615
1616<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1617function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1618'<tt>normal</tt>' label or the
1619'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1620"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1621"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1622href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1623continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1624
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1625<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1626
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1627<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1628
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1629<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1630 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1631 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1632 convention</a> the call should use. If none is specified, the call defaults
1633 to using C calling conventions.
1634 </li>
1635 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1636 function value being invoked. In most cases, this is a direct function
1637 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1638 an arbitrary pointer to function value.
1639 </li>
1640
1641 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1642 function to be invoked. </li>
1643
1644 <li>'<tt>function args</tt>': argument list whose types match the function
1645 signature argument types. If the function signature indicates the function
1646 accepts a variable number of arguments, the extra arguments can be
1647 specified. </li>
1648
1649 <li>'<tt>normal label</tt>': the label reached when the called function
1650 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1651
1652 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1653 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1654
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1655</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1656
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1657<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1658
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1659<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1660href="#i_call">call</a></tt>' instruction in most regards. The primary
1661difference is that it establishes an association with a label, which is used by
1662the runtime library to unwind the stack.</p>
1663
1664<p>This instruction is used in languages with destructors to ensure that proper
1665cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1666exception. Additionally, this is important for implementation of
1667'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1668
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1669<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1670<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1671 %retval = invoke i32 %Test(i32 15) to label %Continue
1672 unwind label %TestCleanup <i>; {i32}:retval set</i>
1673 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1674 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1675</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1676</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1677
1678
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1679<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1680
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1681<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1682Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1683
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1684<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1685
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1686<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1687<pre>
1688 unwind
1689</pre>
1690
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1691<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1692
1693<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1694at the first callee in the dynamic call stack which used an <a
1695href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1696primarily used to implement exception handling.</p>
1697
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1698<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1699
1700<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1701immediately halt. The dynamic call stack is then searched for the first <a
1702href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1703execution continues at the "exceptional" destination block specified by the
1704<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1705dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1706</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1707
1708<!-- _______________________________________________________________________ -->
1709
1710<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1711Instruction</a> </div>
1712
1713<div class="doc_text">
1714
1715<h5>Syntax:</h5>
1716<pre>
1717 unreachable
1718</pre>
1719
1720<h5>Overview:</h5>
1721
1722<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1723instruction is used to inform the optimizer that a particular portion of the
1724code is not reachable. This can be used to indicate that the code after a
1725no-return function cannot be reached, and other facts.</p>
1726
1727<h5>Semantics:</h5>
1728
1729<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1730</div>
1731
1732
1733
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1734<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1735<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1736<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1737<p>Binary operators are used to do most of the computation in a
1738program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1739produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1740multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1741The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1742necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1743<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1744</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1745<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1746<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1747Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1748<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1749<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1750<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]1751</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1752<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1753<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1754<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1755<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1756 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1757 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1758Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1759<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1760<p>The value produced is the integer or floating point sum of the two
1761operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1762<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1763<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]1764</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1765</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1766<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1767<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1768Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1769<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1770<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1771<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]1772</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1773<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1774<p>The '<tt>sub</tt>' instruction returns the difference of its two
1775operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1776<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1777instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1778<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1779<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1780 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1781values.
1782This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1783Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1784<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1785<p>The value produced is the integer or floating point difference of
1786the two operands.</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; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1789 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1790</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1791</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1792<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1793<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1794Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1795<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1796<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1797<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]1798</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1799<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1800<p>The '<tt>mul</tt>' instruction returns the product of its two
1801operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1802<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1803<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1804 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1805values.
1806This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1807Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1808<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1809<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1810two operands.</p>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1811<p>Because the operands are the same width, the result of an integer
1812multiplication is the same whether the operands should be deemed unsigned or
1813signed.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1814<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1815<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]1816</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1817</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1818<!-- _______________________________________________________________________ -->
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1819<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1820</a></div>
1821<div class="doc_text">
1822<h5>Syntax:</h5>
1823<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1824</pre>
1825<h5>Overview:</h5>
1826<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1827operands.</p>
1828<h5>Arguments:</h5>
1829<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1830<a href="#t_integer">integer</a> values. Both arguments must have identical
1831types. This instruction can also take <a href="#t_packed">packed</a> versions
1832of the values in which case the elements must be integers.</p>
1833<h5>Semantics:</h5>
1834<p>The value produced is the unsigned integer quotient of the two operands. This
1835instruction always performs an unsigned division operation, regardless of
1836whether the arguments are unsigned or not.</p>
1837<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1838<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]1839</pre>
1840</div>
1841<!-- _______________________________________________________________________ -->
1842<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1843</a> </div>
1844<div class="doc_text">
1845<h5>Syntax:</h5>
1846<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1847</pre>
1848<h5>Overview:</h5>
1849<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1850operands.</p>
1851<h5>Arguments:</h5>
1852<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1853<a href="#t_integer">integer</a> values. Both arguments must have identical
1854types. This instruction can also take <a href="#t_packed">packed</a> versions
1855of the values in which case the elements must be integers.</p>
1856<h5>Semantics:</h5>
1857<p>The value produced is the signed integer quotient of the two operands. This
1858instruction always performs a signed division operation, regardless of whether
1859the arguments are signed or not.</p>
1860<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1861<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]1862</pre>
1863</div>
1864<!-- _______________________________________________________________________ -->
1865<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1866Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1867<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1868<h5>Syntax:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1869<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]1870</pre>
1871<h5>Overview:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1872<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1873operands.</p>
1874<h5>Arguments:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1875<p>The two arguments to the '<tt>div</tt>' instruction must be
1876<a href="#t_floating">floating point</a> values. Both arguments must have
1877identical types. This instruction can also take <a href="#t_packed">packed</a>
1878versions of the values in which case the elements must be floating point.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1879<h5>Semantics:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1880<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1881<h5>Example:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1882<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]1883</pre>
1884</div>
1885<!-- _______________________________________________________________________ -->
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1886<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1887</div>
1888<div class="doc_text">
1889<h5>Syntax:</h5>
1890<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1891</pre>
1892<h5>Overview:</h5>
1893<p>The '<tt>urem</tt>' instruction returns the remainder from the
1894unsigned division of its two arguments.</p>
1895<h5>Arguments:</h5>
1896<p>The two arguments to the '<tt>urem</tt>' instruction must be
1897<a href="#t_integer">integer</a> values. Both arguments must have identical
1898types.</p>
1899<h5>Semantics:</h5>
1900<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1901This instruction always performs an unsigned division to get the remainder,
1902regardless of whether the arguments are unsigned or not.</p>
1903<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1904<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]1905</pre>
1906
1907</div>
1908<!-- _______________________________________________________________________ -->
1909<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1910Instruction</a> </div>
1911<div class="doc_text">
1912<h5>Syntax:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1913<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]1914</pre>
1915<h5>Overview:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1916<p>The '<tt>srem</tt>' instruction returns the remainder from the
1917signed division of its two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1918<h5>Arguments:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1919<p>The two arguments to the '<tt>srem</tt>' instruction must be
1920<a href="#t_integer">integer</a> values. Both arguments must have identical
1921types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1922<h5>Semantics:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1923<p>This instruction returns the <i>remainder</i> of a division (where the result
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1924has the same sign as the divisor), not the <i>modulus</i> (where the
1925result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1926information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1927 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1928Math Forum</a>.</p>
1929<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1930<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]1931</pre>
1932
1933</div>
1934<!-- _______________________________________________________________________ -->
1935<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
1936Instruction</a> </div>
1937<div class="doc_text">
1938<h5>Syntax:</h5>
1939<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1940</pre>
1941<h5>Overview:</h5>
1942<p>The '<tt>frem</tt>' instruction returns the remainder from the
1943division of its two operands.</p>
1944<h5>Arguments:</h5>
1945<p>The two arguments to the '<tt>frem</tt>' instruction must be
1946<a href="#t_floating">floating point</a> values. Both arguments must have
1947identical types.</p>
1948<h5>Semantics:</h5>
1949<p>This instruction returns the <i>remainder</i> of a division.</p>
1950<h5>Example:</h5>
1951<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]1952</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1953</div>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]1954
Reid Spencer8e11bf82007-02-02 13:57:07 +0000[diff] [blame^]1955<!-- ======================================================================= -->
1956<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1957Operations</a> </div>
1958<div class="doc_text">
1959<p>Bitwise binary operators are used to do various forms of
1960bit-twiddling in a program. They are generally very efficient
1961instructions and can commonly be strength reduced from other
1962instructions. They require two operands, execute an operation on them,
1963and produce a single value. The resulting value of the bitwise binary
1964operators is always the same type as its first operand.</p>
1965</div>
1966
Reid Spencer569f2fa2007-01-31 21:39:12 +0000[diff] [blame]1967<!-- _______________________________________________________________________ -->
1968<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1969Instruction</a> </div>
1970<div class="doc_text">
1971<h5>Syntax:</h5>
1972<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1973</pre>
1974<h5>Overview:</h5>
1975<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1976the left a specified number of bits.</p>
1977<h5>Arguments:</h5>
1978<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
1979 href="#t_integer">integer</a> type.</p>
1980<h5>Semantics:</h5>
1981<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
1982<h5>Example:</h5><pre>
1983 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
1984 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
1985 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
1986</pre>
1987</div>
1988<!-- _______________________________________________________________________ -->
1989<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
1990Instruction</a> </div>
1991<div class="doc_text">
1992<h5>Syntax:</h5>
1993<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1994</pre>
1995
1996<h5>Overview:</h5>
1997<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
1998operand shifted to the right a specified number of bits.</p>
1999
2000<h5>Arguments:</h5>
2001<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2002<a href="#t_integer">integer</a> type.</p>
2003
2004<h5>Semantics:</h5>
2005<p>This instruction always performs a logical shift right operation. The most
2006significant bits of the result will be filled with zero bits after the
2007shift.</p>
2008
2009<h5>Example:</h5>
2010<pre>
2011 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2012 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2013 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2014 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2015</pre>
2016</div>
2017
Reid Spencer8e11bf82007-02-02 13:57:07 +0000[diff] [blame^]2018<!-- _______________________________________________________________________ -->
Reid Spencer569f2fa2007-01-31 21:39:12 +0000[diff] [blame]2019<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2020Instruction</a> </div>
2021<div class="doc_text">
2022
2023<h5>Syntax:</h5>
2024<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2025</pre>
2026
2027<h5>Overview:</h5>
2028<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2029operand shifted to the right a specified number of bits.</p>
2030
2031<h5>Arguments:</h5>
2032<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2033<a href="#t_integer">integer</a> type.</p>
2034
2035<h5>Semantics:</h5>
2036<p>This instruction always performs an arithmetic shift right operation,
2037The most significant bits of the result will be filled with the sign bit
2038of <tt>var1</tt>.</p>
2039
2040<h5>Example:</h5>
2041<pre>
2042 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2043 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2044 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2045 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
2046</pre>
2047</div>
2048
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2049<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2050<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2051Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2052<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2053<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2054<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]2055</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2056<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2057<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2058its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2059<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2060<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2061 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2062identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2063<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2064<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2065<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2066<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2067<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2068 <tbody>
2069 <tr>
2070 <td>In0</td>
2071 <td>In1</td>
2072 <td>Out</td>
2073 </tr>
2074 <tr>
2075 <td>0</td>
2076 <td>0</td>
2077 <td>0</td>
2078 </tr>
2079 <tr>
2080 <td>0</td>
2081 <td>1</td>
2082 <td>0</td>
2083 </tr>
2084 <tr>
2085 <td>1</td>
2086 <td>0</td>
2087 <td>0</td>
2088 </tr>
2089 <tr>
2090 <td>1</td>
2091 <td>1</td>
2092 <td>1</td>
2093 </tr>
2094 </tbody>
2095</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2096</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2097<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2098<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2099 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2100 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</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_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2105<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2106<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2107<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]2108</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2109<h5>Overview:</h5>
2110<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2111or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2112<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2113<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2114 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2115identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2116<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2117<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2118<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2119<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2120<table border="1" cellspacing="0" cellpadding="4">
2121 <tbody>
2122 <tr>
2123 <td>In0</td>
2124 <td>In1</td>
2125 <td>Out</td>
2126 </tr>
2127 <tr>
2128 <td>0</td>
2129 <td>0</td>
2130 <td>0</td>
2131 </tr>
2132 <tr>
2133 <td>0</td>
2134 <td>1</td>
2135 <td>1</td>
2136 </tr>
2137 <tr>
2138 <td>1</td>
2139 <td>0</td>
2140 <td>1</td>
2141 </tr>
2142 <tr>
2143 <td>1</td>
2144 <td>1</td>
2145 <td>1</td>
2146 </tr>
2147 </tbody>
2148</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2149</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2150<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2151<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2152 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2153 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2154</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2155</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2156<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2157<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2158Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2159<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2160<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2161<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]2162</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2163<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2164<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2165or of its two operands. The <tt>xor</tt> is used to implement the
2166"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2167<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2168<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2169 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2170identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2171<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2172<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2173<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2174<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2175<table border="1" cellspacing="0" cellpadding="4">
2176 <tbody>
2177 <tr>
2178 <td>In0</td>
2179 <td>In1</td>
2180 <td>Out</td>
2181 </tr>
2182 <tr>
2183 <td>0</td>
2184 <td>0</td>
2185 <td>0</td>
2186 </tr>
2187 <tr>
2188 <td>0</td>
2189 <td>1</td>
2190 <td>1</td>
2191 </tr>
2192 <tr>
2193 <td>1</td>
2194 <td>0</td>
2195 <td>1</td>
2196 </tr>
2197 <tr>
2198 <td>1</td>
2199 <td>1</td>
2200 <td>0</td>
2201 </tr>
2202 </tbody>
2203</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2204</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2205<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2206<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2207<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2208 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2209 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2210 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2211</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2212</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2213
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2214<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2215<div class="doc_subsection">
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2216 <a name="vectorops">Vector Operations</a>
2217</div>
2218
2219<div class="doc_text">
2220
2221<p>LLVM supports several instructions to represent vector operations in a
2222target-independent manner. This instructions cover the element-access and
2223vector-specific operations needed to process vectors effectively. While LLVM
2224does directly support these vector operations, many sophisticated algorithms
2225will want to use target-specific intrinsics to take full advantage of a specific
2226target.</p>
2227
2228</div>
2229
2230<!-- _______________________________________________________________________ -->
2231<div class="doc_subsubsection">
2232 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2233</div>
2234
2235<div class="doc_text">
2236
2237<h5>Syntax:</h5>
2238
2239<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2240 &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]2241</pre>
2242
2243<h5>Overview:</h5>
2244
2245<p>
2246The '<tt>extractelement</tt>' instruction extracts a single scalar
2247element from a packed vector at a specified index.
2248</p>
2249
2250
2251<h5>Arguments:</h5>
2252
2253<p>
2254The first operand of an '<tt>extractelement</tt>' instruction is a
2255value of <a href="#t_packed">packed</a> type. The second operand is
2256an index indicating the position from which to extract the element.
2257The index may be a variable.</p>
2258
2259<h5>Semantics:</h5>
2260
2261<p>
2262The result is a scalar of the same type as the element type of
2263<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2264<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2265results are undefined.
2266</p>
2267
2268<h5>Example:</h5>
2269
2270<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2271 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2272</pre>
2273</div>
2274
2275
2276<!-- _______________________________________________________________________ -->
2277<div class="doc_subsubsection">
2278 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2279</div>
2280
2281<div class="doc_text">
2282
2283<h5>Syntax:</h5>
2284
2285<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2286 &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]2287</pre>
2288
2289<h5>Overview:</h5>
2290
2291<p>
2292The '<tt>insertelement</tt>' instruction inserts a scalar
2293element into a packed vector at a specified index.
2294</p>
2295
2296
2297<h5>Arguments:</h5>
2298
2299<p>
2300The first operand of an '<tt>insertelement</tt>' instruction is a
2301value of <a href="#t_packed">packed</a> type. The second operand is a
2302scalar value whose type must equal the element type of the first
2303operand. The third operand is an index indicating the position at
2304which to insert the value. The index may be a variable.</p>
2305
2306<h5>Semantics:</h5>
2307
2308<p>
2309The result is a packed vector of the same type as <tt>val</tt>. Its
2310element values are those of <tt>val</tt> except at position
2311<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2312exceeds the length of <tt>val</tt>, the results are undefined.
2313</p>
2314
2315<h5>Example:</h5>
2316
2317<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2318 %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]2319</pre>
2320</div>
2321
2322<!-- _______________________________________________________________________ -->
2323<div class="doc_subsubsection">
2324 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2325</div>
2326
2327<div class="doc_text">
2328
2329<h5>Syntax:</h5>
2330
2331<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2332 &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]2333</pre>
2334
2335<h5>Overview:</h5>
2336
2337<p>
2338The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2339from two input vectors, returning a vector of the same type.
2340</p>
2341
2342<h5>Arguments:</h5>
2343
2344<p>
2345The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2346with types that match each other and types that match the result of the
2347instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2348of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2349</p>
2350
2351<p>
2352The shuffle mask operand is required to be a constant vector with either
2353constant integer or undef values.
2354</p>
2355
2356<h5>Semantics:</h5>
2357
2358<p>
2359The elements of the two input vectors are numbered from left to right across
2360both of the vectors. The shuffle mask operand specifies, for each element of
2361the result vector, which element of the two input registers the result element
2362gets. The element selector may be undef (meaning "don't care") and the second
2363operand may be undef if performing a shuffle from only one vector.
2364</p>
2365
2366<h5>Example:</h5>
2367
2368<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2369 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2370 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2371 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2372 &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]2373</pre>
2374</div>
2375
Tanya Lattner09474292006-04-14 19:24:33 +0000[diff] [blame]2376
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2377<!-- ======================================================================= -->
2378<div class="doc_subsection">
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2379 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2380</div>
2381
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2382<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2383
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2384<p>A key design point of an SSA-based representation is how it
2385represents memory. In LLVM, no memory locations are in SSA form, which
2386makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2387allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2388
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2389</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2390
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2391<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2392<div class="doc_subsubsection">
2393 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2394</div>
2395
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2396<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2397
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2398<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2399
2400<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2401 &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]2402</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2403
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2404<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2405
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2406<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2407heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2408
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2409<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2410
2411<p>The '<tt>malloc</tt>' instruction allocates
2412<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]2413bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2414appropriate type to the program. If "NumElements" is specified, it is the
2415number of elements allocated. If an alignment is specified, the value result
2416of the allocation is guaranteed to be aligned to at least that boundary. If
2417not specified, or if zero, the target can choose to align the allocation on any
2418convenient boundary.</p>
2419
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2420<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2421
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2422<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2423
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2424<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2425a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2426
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2427<h5>Example:</h5>
2428
2429<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2430 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2431
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2432 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2433 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2434 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2435 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2436 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2437</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2438</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2439
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2440<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2441<div class="doc_subsubsection">
2442 <a name="i_free">'<tt>free</tt>' Instruction</a>
2443</div>
2444
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2445<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2446
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2447<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2448
2449<pre>
2450 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2451</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2452
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2453<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2454
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2455<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2456memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2457
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2458<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2459
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2460<p>'<tt>value</tt>' shall be a pointer value that points to a value
2461that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2462instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2463
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2464<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2465
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2466<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2467after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2468
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2469<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2470
2471<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2472 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2473 free [4 x i8]* %array
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2474</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2475</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2476
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2477<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2478<div class="doc_subsubsection">
2479 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2480</div>
2481
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2482<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2483
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2484<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2485
2486<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2487 &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]2488</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2489
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2490<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2491
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2492<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2493stack frame of the procedure that is live until the current function
2494returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2495
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2496<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2497
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2498<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2499bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2500appropriate type to the program. If "NumElements" is specified, it is the
2501number of elements allocated. If an alignment is specified, the value result
2502of the allocation is guaranteed to be aligned to at least that boundary. If
2503not specified, or if zero, the target can choose to align the allocation on any
2504convenient boundary.</p>
2505
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2506<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2507
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2508<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2509
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2510<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2511memory is automatically released when the function returns. The '<tt>alloca</tt>'
2512instruction is commonly used to represent automatic variables that must
2513have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]2514 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]2515instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2516
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2517<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2518
2519<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2520 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2521 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2522 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2523 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2524</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2525</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2526
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2527<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2528<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2529Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2530<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2531<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2532<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]2533<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2534<p>The '<tt>load</tt>' instruction is used to read from 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>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2537address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2538 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2539marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2540the number or order of execution of this <tt>load</tt> with other
2541volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2542instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2543<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2544<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2545<h5>Examples:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2546<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2547 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2548 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2549 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2550</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2551</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2552<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2553<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2554Instruction</a> </div>
Reid Spencer035ab572006-11-09 21:18:01 +0000[diff] [blame]2555<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2556<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2557<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]2558 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]2559</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2560<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2561<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2562<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2563<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2564to 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]2565operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2566operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2567optimizer is not allowed to modify the number or order of execution of
2568this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2569 href="#i_store">store</a></tt> instructions.</p>
2570<h5>Semantics:</h5>
2571<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2572at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2573<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2574<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2575 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2576 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2577 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2578</pre>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2579</div>
2580
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2581<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2582<div class="doc_subsubsection">
2583 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2584</div>
2585
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2586<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2587<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2588<pre>
2589 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2590</pre>
2591
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2592<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2593
2594<p>
2595The '<tt>getelementptr</tt>' instruction is used to get the address of a
2596subelement of an aggregate data structure.</p>
2597
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2598<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2599
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2600<p>This instruction takes a list of integer operands that indicate what
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2601elements of the aggregate object to index to. The actual types of the arguments
2602provided depend on the type of the first pointer argument. The
2603'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2604levels 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]2605structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2606into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2607be sign extended to 64-bit values.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2608
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2609<p>For example, let's consider a C code fragment and how it gets
2610compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2611
2612<pre>
2613 struct RT {
2614 char A;
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2615 i32 B[10][20];
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2616 char C;
2617 };
2618 struct ST {
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2619 i32 X;
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2620 double Y;
2621 struct RT Z;
2622 };
2623
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2624 define i32 *foo(struct ST *s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2625 return &amp;s[1].Z.B[5][13];
2626 }
2627</pre>
2628
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2629<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2630
2631<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2632 %RT = type { i8 , [10 x [20 x i32]], i8 }
2633 %ST = type { i32, double, %RT }
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2634
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2635 implementation
2636
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2637 define i32* %foo(%ST* %s) {
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2638 entry:
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2639 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2640 ret i32* %reg
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2641 }
2642</pre>
2643
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2644<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2645
2646<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2647on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2648and <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]2649<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]2650to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencer42ddd842006-12-03 16:53:48 +0000[diff] [blame]2651<b>constants</b>.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2652
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2653<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]2654type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2655}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2656the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2657i8 }</tt>' type, another structure. The third index indexes into the second
2658element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2659array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2660'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2661to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2662
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2663<p>Note that it is perfectly legal to index partially through a
2664structure, returning a pointer to an inner element. Because of this,
2665the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2666
2667<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2668 define i32* %foo(%ST* %s) {
2669 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2670 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2671 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2672 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2673 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2674 ret i32* %t5
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2675 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2676</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2677
2678<p>Note that it is undefined to access an array out of bounds: array and
2679pointer indexes must always be within the defined bounds of the array type.
2680The one exception for this rules is zero length arrays. These arrays are
2681defined to be accessible as variable length arrays, which requires access
2682beyond the zero'th element.</p>
2683
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2684<p>The getelementptr instruction is often confusing. For some more insight
2685into how it works, see <a href="GetElementPtr.html">the getelementptr
2686FAQ</a>.</p>
2687
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2688<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2689
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2690<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2691 <i>; yields [12 x i8]*:aptr</i>
2692 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2693</pre>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2694</div>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2695
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2696<!-- ======================================================================= -->
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2697<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2698</div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2699<div class="doc_text">
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2700<p>The instructions in this category are the conversion instructions (casting)
2701which all take a single operand and a type. They perform various bit conversions
2702on the operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2703</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2704
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2705<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2706<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2707 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2708</div>
2709<div class="doc_text">
2710
2711<h5>Syntax:</h5>
2712<pre>
2713 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2714</pre>
2715
2716<h5>Overview:</h5>
2717<p>
2718The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2719</p>
2720
2721<h5>Arguments:</h5>
2722<p>
2723The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2724be 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]2725and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2726type. The bit size of <tt>value</tt> must be larger than the bit size of
2727<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2728
2729<h5>Semantics:</h5>
2730<p>
2731The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2732and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2733larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2734It will always truncate bits.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2735
2736<h5>Example:</h5>
2737<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2738 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2739 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2740 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2741</pre>
2742</div>
2743
2744<!-- _______________________________________________________________________ -->
2745<div class="doc_subsubsection">
2746 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2747</div>
2748<div class="doc_text">
2749
2750<h5>Syntax:</h5>
2751<pre>
2752 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2753</pre>
2754
2755<h5>Overview:</h5>
2756<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2757<tt>ty2</tt>.</p>
2758
2759
2760<h5>Arguments:</h5>
2761<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]2762<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2763also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2764<tt>value</tt> must be smaller than the bit size of the destination type,
2765<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2766
2767<h5>Semantics:</h5>
2768<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2769bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2770the operand and the type are the same size, no bit filling is done and the
2771cast is considered a <i>no-op cast</i> because no bits change (only the type
2772changes).</p>
2773
Reid Spencerb5929522007-01-12 15:46:11 +0000[diff] [blame]2774<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]2775
2776<h5>Example:</h5>
2777<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2778 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2779 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2780</pre>
2781</div>
2782
2783<!-- _______________________________________________________________________ -->
2784<div class="doc_subsubsection">
2785 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2786</div>
2787<div class="doc_text">
2788
2789<h5>Syntax:</h5>
2790<pre>
2791 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2792</pre>
2793
2794<h5>Overview:</h5>
2795<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2796
2797<h5>Arguments:</h5>
2798<p>
2799The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2800<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2801also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2802<tt>value</tt> must be smaller than the bit size of the destination type,
2803<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2804
2805<h5>Semantics:</h5>
2806<p>
2807The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2808bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2809the type <tt>ty2</tt>. When the the operand and the type are the same size,
2810no bit filling is done and the cast is considered a <i>no-op cast</i> because
2811no bits change (only the type changes).</p>
2812
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2813<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]2814
2815<h5>Example:</h5>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2816<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2817 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2818 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2819</pre>
2820</div>
2821
2822<!-- _______________________________________________________________________ -->
2823<div class="doc_subsubsection">
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2824 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2825</div>
2826
2827<div class="doc_text">
2828
2829<h5>Syntax:</h5>
2830
2831<pre>
2832 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2833</pre>
2834
2835<h5>Overview:</h5>
2836<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2837<tt>ty2</tt>.</p>
2838
2839
2840<h5>Arguments:</h5>
2841<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2842 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2843cast it to. The size of <tt>value</tt> must be larger than the size of
2844<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2845<i>no-op cast</i>.</p>
2846
2847<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2848<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2849<a href="#t_floating">floating point</a> type to a smaller
2850<a href="#t_floating">floating point</a> type. If the value cannot fit within
2851the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2852
2853<h5>Example:</h5>
2854<pre>
2855 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2856 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2857</pre>
2858</div>
2859
2860<!-- _______________________________________________________________________ -->
2861<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2862 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2863</div>
2864<div class="doc_text">
2865
2866<h5>Syntax:</h5>
2867<pre>
2868 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2869</pre>
2870
2871<h5>Overview:</h5>
2872<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2873floating point value.</p>
2874
2875<h5>Arguments:</h5>
2876<p>The '<tt>fpext</tt>' instruction takes a
2877<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2878and a <a href="#t_floating">floating point</a> type to cast it to. The source
2879type must be smaller than the destination type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2880
2881<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2882<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
2883<a href="t_floating">floating point</a> type to a larger
2884<a href="t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
2885used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]2886<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]2887
2888<h5>Example:</h5>
2889<pre>
2890 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2891 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2892</pre>
2893</div>
2894
2895<!-- _______________________________________________________________________ -->
2896<div class="doc_subsubsection">
Reid Spencer24d6da52007-01-21 00:29:26 +0000[diff] [blame]2897 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2898</div>
2899<div class="doc_text">
2900
2901<h5>Syntax:</h5>
2902<pre>
2903 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2904</pre>
2905
2906<h5>Overview:</h5>
2907<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2908unsigned integer equivalent of type <tt>ty2</tt>.
2909</p>
2910
2911<h5>Arguments:</h5>
2912<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2913<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]2914must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2915
2916<h5>Semantics:</h5>
2917<p> The '<tt>fp2uint</tt>' instruction converts its
2918<a href="#t_floating">floating point</a> operand into the nearest (rounding
2919towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2920the results are undefined.</p>
2921
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2922<p>When converting to i1, the conversion is done as a comparison against
2923zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2924If 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]2925
2926<h5>Example:</h5>
2927<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2928 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
2929 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2930 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2931</pre>
2932</div>
2933
2934<!-- _______________________________________________________________________ -->
2935<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2936 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2937</div>
2938<div class="doc_text">
2939
2940<h5>Syntax:</h5>
2941<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2942 &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]2943</pre>
2944
2945<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2946<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2947<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]2948</p>
2949
2950
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2951<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2952<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]2953<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]2954must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2955
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2956<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2957<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2958<a href="#t_floating">floating point</a> operand into the nearest (rounding
2959towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
2960the results are undefined.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2961
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2962<p>When converting to i1, the conversion is done as a comparison against
2963zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2964If 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]2965
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2966<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2967<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2968 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
2969 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2970 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2971</pre>
2972</div>
2973
2974<!-- _______________________________________________________________________ -->
2975<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2976 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2977</div>
2978<div class="doc_text">
2979
2980<h5>Syntax:</h5>
2981<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2982 &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]2983</pre>
2984
2985<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2986<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2987integer and converts that value to the <tt>ty2</tt> type.</p>
2988
2989
2990<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2991<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]2992<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]2993be a <a href="#t_floating">floating point</a> type.</p>
2994
2995<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2996<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2997integer quantity and converts it to the corresponding floating point value. If
2998the value cannot fit in the floating point value, the results are undefined.</p>
2999
3000
3001<h5>Example:</h5>
3002<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3003 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3004 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3005</pre>
3006</div>
3007
3008<!-- _______________________________________________________________________ -->
3009<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3010 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3011</div>
3012<div class="doc_text">
3013
3014<h5>Syntax:</h5>
3015<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3016 &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]3017</pre>
3018
3019<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3020<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3021integer and converts that value to the <tt>ty2</tt> type.</p>
3022
3023<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3024<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]3025<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]3026a <a href="#t_floating">floating point</a> type.</p>
3027
3028<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3029<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3030integer quantity and converts it to the corresponding floating point value. If
3031the value cannot fit in the floating point value, the results are undefined.</p>
3032
3033<h5>Example:</h5>
3034<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3035 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3036 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3037</pre>
3038</div>
3039
3040<!-- _______________________________________________________________________ -->
3041<div class="doc_subsubsection">
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3042 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3043</div>
3044<div class="doc_text">
3045
3046<h5>Syntax:</h5>
3047<pre>
3048 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3049</pre>
3050
3051<h5>Overview:</h5>
3052<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3053the integer type <tt>ty2</tt>.</p>
3054
3055<h5>Arguments:</h5>
3056<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3057must be a <a href="t_pointer">pointer</a> value, and a type to cast it to
3058<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3059
3060<h5>Semantics:</h5>
3061<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3062<tt>ty2</tt> by interpreting the pointer value as an integer and either
3063truncating or zero extending that value to the size of the integer type. If
3064<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3065<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3066are the same size, then nothing is done (<i>no-op cast</i>).</p>
3067
3068<h5>Example:</h5>
3069<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3070 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3071 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3072</pre>
3073</div>
3074
3075<!-- _______________________________________________________________________ -->
3076<div class="doc_subsubsection">
3077 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3078</div>
3079<div class="doc_text">
3080
3081<h5>Syntax:</h5>
3082<pre>
3083 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3084</pre>
3085
3086<h5>Overview:</h5>
3087<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3088a pointer type, <tt>ty2</tt>.</p>
3089
3090<h5>Arguments:</h5>
3091<p>The '<tt>inttoptr</tt>' instruction takes an <a href="i_integer">integer</a>
3092value to cast, and a type to cast it to, which must be a
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]3093<a href="#t_pointer">pointer</a> type.
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3094
3095<h5>Semantics:</h5>
3096<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3097<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3098the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3099size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3100the size of a pointer then a zero extension is done. If they are the same size,
3101nothing is done (<i>no-op cast</i>).</p>
3102
3103<h5>Example:</h5>
3104<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3105 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3106 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3107 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3108</pre>
3109</div>
3110
3111<!-- _______________________________________________________________________ -->
3112<div class="doc_subsubsection">
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3113 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3114</div>
3115<div class="doc_text">
3116
3117<h5>Syntax:</h5>
3118<pre>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3119 &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]3120</pre>
3121
3122<h5>Overview:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3123<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3124<tt>ty2</tt> without changing any bits.</p>
3125
3126<h5>Arguments:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3127<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3128a first class value, and a type to cast it to, which must also be a <a
3129 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencer19b569f2007-01-09 20:08:58 +0000[diff] [blame]3130and the destination type, <tt>ty2</tt>, must be identical. If the source
3131type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3132
3133<h5>Semantics:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3134<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3135<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3136this conversion. The conversion is done as if the <tt>value</tt> had been
3137stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3138converted to other pointer types with this instruction. To convert pointers to
3139other types, use the <a href="#i_inttoptr">inttoptr</a> or
3140<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3141
3142<h5>Example:</h5>
3143<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3144 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3145 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3146 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]3147</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3148</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3149
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3150<!-- ======================================================================= -->
3151<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3152<div class="doc_text">
3153<p>The instructions in this category are the "miscellaneous"
3154instructions, which defy better classification.</p>
3155</div>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3156
3157<!-- _______________________________________________________________________ -->
3158<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3159</div>
3160<div class="doc_text">
3161<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3162<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3163<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3164</pre>
3165<h5>Overview:</h5>
3166<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3167of its two integer operands.</p>
3168<h5>Arguments:</h5>
3169<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3170the condition code which indicates the kind of comparison to perform. It is not
3171a value, just a keyword. The possibilities for the condition code are:
3172<ol>
3173 <li><tt>eq</tt>: equal</li>
3174 <li><tt>ne</tt>: not equal </li>
3175 <li><tt>ugt</tt>: unsigned greater than</li>
3176 <li><tt>uge</tt>: unsigned greater or equal</li>
3177 <li><tt>ult</tt>: unsigned less than</li>
3178 <li><tt>ule</tt>: unsigned less or equal</li>
3179 <li><tt>sgt</tt>: signed greater than</li>
3180 <li><tt>sge</tt>: signed greater or equal</li>
3181 <li><tt>slt</tt>: signed less than</li>
3182 <li><tt>sle</tt>: signed less or equal</li>
3183</ol>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3184<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3185<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3186<h5>Semantics:</h5>
3187<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3188the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3189yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3190<ol>
3191 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3192 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3193 </li>
3194 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3195 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3196 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3197 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3198 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3199 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3200 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3201 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3202 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3203 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3204 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3205 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3206 <li><tt>sge</tt>: interprets the operands as signed values and yields
3207 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3208 <li><tt>slt</tt>: interprets the operands as signed values and yields
3209 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3210 <li><tt>sle</tt>: interprets the operands as signed values and yields
3211 <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]3212</ol>
3213<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3214values are treated as integers and then compared.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3215
3216<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3217<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3218 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3219 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3220 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3221 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3222 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3223</pre>
3224</div>
3225
3226<!-- _______________________________________________________________________ -->
3227<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3228</div>
3229<div class="doc_text">
3230<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3231<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3232<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3233</pre>
3234<h5>Overview:</h5>
3235<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3236of its floating point operands.</p>
3237<h5>Arguments:</h5>
3238<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3239the condition code which indicates the kind of comparison to perform. It is not
3240a value, just a keyword. The possibilities for the condition code are:
3241<ol>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3242 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3243 <li><tt>oeq</tt>: ordered and equal</li>
3244 <li><tt>ogt</tt>: ordered and greater than </li>
3245 <li><tt>oge</tt>: ordered and greater than or equal</li>
3246 <li><tt>olt</tt>: ordered and less than </li>
3247 <li><tt>ole</tt>: ordered and less than or equal</li>
3248 <li><tt>one</tt>: ordered and not equal</li>
3249 <li><tt>ord</tt>: ordered (no nans)</li>
3250 <li><tt>ueq</tt>: unordered or equal</li>
3251 <li><tt>ugt</tt>: unordered or greater than </li>
3252 <li><tt>uge</tt>: unordered or greater than or equal</li>
3253 <li><tt>ult</tt>: unordered or less than </li>
3254 <li><tt>ule</tt>: unordered or less than or equal</li>
3255 <li><tt>une</tt>: unordered or not equal</li>
3256 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3257 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3258</ol>
Reid Spencer93a49852006-12-06 07:08:07 +0000[diff] [blame]3259<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3260<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3261<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3262<a href="#t_floating">floating point</a> typed. They must have identical
3263types.</p>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3264<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3265<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3266<h5>Semantics:</h5>
3267<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3268the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3269yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3270<ol>
3271 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3272 <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]3273 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3274 <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]3275 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3276 <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]3277 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3278 <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]3279 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3280 <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]3281 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3282 <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]3283 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3284 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3285 <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]3286 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3287 <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]3288 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3289 <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]3290 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3291 <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]3292 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3293 <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]3294 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3295 <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]3296 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3297 <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]3298 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3299</ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3300
3301<h5>Example:</h5>
3302<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3303 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3304 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3305 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3306</pre>
3307</div>
3308
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3309<!-- _______________________________________________________________________ -->
3310<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3311Instruction</a> </div>
3312<div class="doc_text">
3313<h5>Syntax:</h5>
3314<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3315<h5>Overview:</h5>
3316<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3317the SSA graph representing the function.</p>
3318<h5>Arguments:</h5>
3319<p>The type of the incoming values are specified with the first type
3320field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3321as arguments, with one pair for each predecessor basic block of the
3322current block. Only values of <a href="#t_firstclass">first class</a>
3323type may be used as the value arguments to the PHI node. Only labels
3324may be used as the label arguments.</p>
3325<p>There must be no non-phi instructions between the start of a basic
3326block and the PHI instructions: i.e. PHI instructions must be first in
3327a basic block.</p>
3328<h5>Semantics:</h5>
3329<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3330value specified by the parameter, depending on which basic block we
3331came from in the last <a href="#terminators">terminator</a> instruction.</p>
3332<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3333<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]3334</div>
3335
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3336<!-- _______________________________________________________________________ -->
3337<div class="doc_subsubsection">
3338 <a name="i_select">'<tt>select</tt>' Instruction</a>
3339</div>
3340
3341<div class="doc_text">
3342
3343<h5>Syntax:</h5>
3344
3345<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3346 &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]3347</pre>
3348
3349<h5>Overview:</h5>
3350
3351<p>
3352The '<tt>select</tt>' instruction is used to choose one value based on a
3353condition, without branching.
3354</p>
3355
3356
3357<h5>Arguments:</h5>
3358
3359<p>
3360The '<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.
3361</p>
3362
3363<h5>Semantics:</h5>
3364
3365<p>
3366If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3367value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3368</p>
3369
3370<h5>Example:</h5>
3371
3372<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3373 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3374</pre>
3375</div>
3376
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]3377
3378<!-- _______________________________________________________________________ -->
3379<div class="doc_subsubsection">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3380 <a name="i_call">'<tt>call</tt>' Instruction</a>
3381</div>
3382
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3383<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3384
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3385<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3386<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3387 &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]3388</pre>
3389
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3390<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3391
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3392<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3393
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3394<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3395
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3396<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3397
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3398<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3399 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3400 <p>The optional "tail" marker indicates whether the callee function accesses
3401 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3402 function call is eligible for tail call optimization. Note that calls may
3403 be marked "tail" even if they do not occur before a <a
3404 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3405 </li>
3406 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3407 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
3408 convention</a> the call should use. If none is specified, the call defaults
3409 to using C calling conventions.
3410 </li>
3411 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3412 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3413 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3414 signature. This type can be omitted if the function is not varargs and
3415 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3416 </li>
3417 <li>
3418 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3419 be invoked. In most cases, this is a direct function invocation, but
3420 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3421 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3422 </li>
3423 <li>
3424 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]3425 function signature argument types. All arguments must be of
3426 <a href="#t_firstclass">first class</a> type. If the function signature
3427 indicates the function accepts a variable number of arguments, the extra
3428 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3429 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3430</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3431
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3432<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3433
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3434<p>The '<tt>call</tt>' instruction is used to cause control flow to
3435transfer to a specified function, with its incoming arguments bound to
3436the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3437instruction in the called function, control flow continues with the
3438instruction after the function call, and the return value of the
3439function is bound to the result argument. This is a simpler case of
3440the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3441
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3442<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3443
3444<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3445 %retval = call i32 %test(i32 %argc)
3446 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3447 %X = tail call i32 %foo()
3448 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3449</pre>
3450
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3451</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3452
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3453<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3454<div class="doc_subsubsection">
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3455 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3456</div>
3457
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3458<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3459
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3460<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3461
3462<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3463 &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]3464</pre>
3465
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3466<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3467
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3468<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3469the "variable argument" area of a function call. It is used to implement the
3470<tt>va_arg</tt> macro in C.</p>
3471
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3472<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3473
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3474<p>This instruction takes a <tt>va_list*</tt> value and the type of
3475the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3476increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3477actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3478
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3479<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3480
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3481<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3482type from the specified <tt>va_list</tt> and causes the
3483<tt>va_list</tt> to point to the next argument. For more information,
3484see the variable argument handling <a href="#int_varargs">Intrinsic
3485Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3486
3487<p>It is legal for this instruction to be called in a function which does not
3488take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3489function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3490
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3491<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3492href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3493argument.</p>
3494
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3495<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3496
3497<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3498
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3499</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3500
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3501<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3502<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3503<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3504
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3505<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3506
3507<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3508well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3509restrictions. Overall, these instructions represent an extension mechanism for
3510the LLVM language that does not require changing all of the transformations in
3511LLVM to add to the language (or the bytecode reader/writer, the parser,
3512etc...).</p>
3513
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3514<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3515prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3516this. Intrinsic functions must always be external functions: you cannot define
3517the body of intrinsic functions. Intrinsic functions may only be used in call
3518or invoke instructions: it is illegal to take the address of an intrinsic
3519function. Additionally, because intrinsic functions are part of the LLVM
3520language, it is required that they all be documented here if any are added.</p>
3521
3522
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3523<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]3524href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3525</p>
3526
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3527</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3528
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3529<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3530<div class="doc_subsection">
3531 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3532</div>
3533
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3534<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3535
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3536<p>Variable argument support is defined in LLVM with the <a
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3537 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3538intrinsic functions. These functions are related to the similarly
3539named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3540
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3541<p>All of these functions operate on arguments that use a
3542target-specific value type "<tt>va_list</tt>". The LLVM assembly
3543language reference manual does not define what this type is, so all
3544transformations should be prepared to handle intrinsics with any type
3545used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3546
Chris Lattner374ab302006-05-15 17:26:46 +0000[diff] [blame]3547<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]3548instruction and the variable argument handling intrinsic functions are
3549used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3550
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3551<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3552define i32 %test(i32 %X, ...) {
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3553 ; Initialize variable argument processing
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3554 %ap = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3555 %ap2 = bitcast i8** %ap to i8*
3556 call void %<a href="#i_va_start">llvm.va_start</a>(i8* %ap2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3557
3558 ; Read a single integer argument
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3559 %tmp = va_arg i8 ** %ap, i32
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3560
3561 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3562 %aq = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3563 %aq2 = bitcast i8** %aq to i8*
3564 call void %<a href="#i_va_copy">llvm.va_copy</a>(i8 *%aq2, i8* %ap2)
3565 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %aq2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3566
3567 ; Stop processing of arguments.
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3568 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %ap2)
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3569 ret i32 %tmp
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3570}
3571</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3572</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3573
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3574<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3575<div class="doc_subsubsection">
3576 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3577</div>
3578
3579
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3580<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3581<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3582<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3583<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3584<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3585<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3586href="#i_va_arg">va_arg</a></tt>.</p>
3587
3588<h5>Arguments:</h5>
3589
3590<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3591
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3592<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3593
3594<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3595macro available in C. In a target-dependent way, it initializes the
3596<tt>va_list</tt> element the argument points to, so that the next call to
3597<tt>va_arg</tt> will produce the first variable argument passed to the function.
3598Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3599last argument of the function, the compiler can figure that out.</p>
3600
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3601</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3602
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3603<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3604<div class="doc_subsubsection">
3605 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3606</div>
3607
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3608<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3609<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3610<pre> declare void %llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3611<h5>Overview:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3612
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3613<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
3614which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
3615or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3616
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3617<h5>Arguments:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3618
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3619<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3620
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3621<h5>Semantics:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3622
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3623<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]3624macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
3625Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
3626 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
3627with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3628
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3629</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3630
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3631<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3632<div class="doc_subsubsection">
3633 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3634</div>
3635
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3636<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3637
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3638<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3639
3640<pre>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3641 declare void %llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3642</pre>
3643
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3644<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3645
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3646<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3647the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3648
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3649<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3650
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3651<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]3652The 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]3653
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3654
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3655<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3656
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3657<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3658available in C. In a target-dependent way, it copies the source
3659<tt>va_list</tt> element into the destination list. This intrinsic is necessary
3660because 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]3661arbitrarily complex and require memory allocation, for example.</p>
3662
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3663</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3664
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3665<!-- ======================================================================= -->
3666<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3667 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3668</div>
3669
3670<div class="doc_text">
3671
3672<p>
3673LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3674Collection</a> requires the implementation and generation of these intrinsics.
3675These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
3676stack</a>, as well as garbage collector implementations that require <a
3677href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
3678Front-ends for type-safe garbage collected languages should generate these
3679intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3680href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3681</p>
3682</div>
3683
3684<!-- _______________________________________________________________________ -->
3685<div class="doc_subsubsection">
3686 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3687</div>
3688
3689<div class="doc_text">
3690
3691<h5>Syntax:</h5>
3692
3693<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3694 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3695</pre>
3696
3697<h5>Overview:</h5>
3698
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]3699<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]3700the code generator, and allows some metadata to be associated with it.</p>
3701
3702<h5>Arguments:</h5>
3703
3704<p>The first argument specifies the address of a stack object that contains the
3705root pointer. The second pointer (which must be either a constant or a global
3706value address) contains the meta-data to be associated with the root.</p>
3707
3708<h5>Semantics:</h5>
3709
3710<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3711location. At compile-time, the code generator generates information to allow
3712the runtime to find the pointer at GC safe points.
3713</p>
3714
3715</div>
3716
3717
3718<!-- _______________________________________________________________________ -->
3719<div class="doc_subsubsection">
3720 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
3721</div>
3722
3723<div class="doc_text">
3724
3725<h5>Syntax:</h5>
3726
3727<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3728 declare i8 * %llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3729</pre>
3730
3731<h5>Overview:</h5>
3732
3733<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3734locations, allowing garbage collector implementations that require read
3735barriers.</p>
3736
3737<h5>Arguments:</h5>
3738
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3739<p>The second argument is the address to read from, which should be an address
3740allocated from the garbage collector. The first object is a pointer to the
3741start of the referenced object, if needed by the language runtime (otherwise
3742null).</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3743
3744<h5>Semantics:</h5>
3745
3746<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3747instruction, but may be replaced with substantially more complex code by the
3748garbage collector runtime, as needed.</p>
3749
3750</div>
3751
3752
3753<!-- _______________________________________________________________________ -->
3754<div class="doc_subsubsection">
3755 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
3756</div>
3757
3758<div class="doc_text">
3759
3760<h5>Syntax:</h5>
3761
3762<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3763 declare void %llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3764</pre>
3765
3766<h5>Overview:</h5>
3767
3768<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3769locations, allowing garbage collector implementations that require write
3770barriers (such as generational or reference counting collectors).</p>
3771
3772<h5>Arguments:</h5>
3773
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3774<p>The first argument is the reference to store, the second is the start of the
3775object to store it to, and the third is the address of the field of Obj to
3776store to. If the runtime does not require a pointer to the object, Obj may be
3777null.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3778
3779<h5>Semantics:</h5>
3780
3781<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3782instruction, but may be replaced with substantially more complex code by the
3783garbage collector runtime, as needed.</p>
3784
3785</div>
3786
3787
3788
3789<!-- ======================================================================= -->
3790<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3791 <a name="int_codegen">Code Generator Intrinsics</a>
3792</div>
3793
3794<div class="doc_text">
3795<p>
3796These intrinsics are provided by LLVM to expose special features that may only
3797be implemented with code generator support.
3798</p>
3799
3800</div>
3801
3802<!-- _______________________________________________________________________ -->
3803<div class="doc_subsubsection">
3804 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
3805</div>
3806
3807<div class="doc_text">
3808
3809<h5>Syntax:</h5>
3810<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3811 declare i8 *%llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3812</pre>
3813
3814<h5>Overview:</h5>
3815
3816<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3817The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3818target-specific value indicating the return address of the current function
3819or one of its callers.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3820</p>
3821
3822<h5>Arguments:</h5>
3823
3824<p>
3825The argument to this intrinsic indicates which function to return the address
3826for. Zero indicates the calling function, one indicates its caller, etc. The
3827argument is <b>required</b> to be a constant integer value.
3828</p>
3829
3830<h5>Semantics:</h5>
3831
3832<p>
3833The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3834the return address of the specified call frame, or zero if it cannot be
3835identified. The value returned by this intrinsic is likely to be incorrect or 0
3836for arguments other than zero, so it should only be used for debugging purposes.
3837</p>
3838
3839<p>
3840Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3841aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3842source-language caller.
3843</p>
3844</div>
3845
3846
3847<!-- _______________________________________________________________________ -->
3848<div class="doc_subsubsection">
3849 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
3850</div>
3851
3852<div class="doc_text">
3853
3854<h5>Syntax:</h5>
3855<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3856 declare i8 *%llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3857</pre>
3858
3859<h5>Overview:</h5>
3860
3861<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3862The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3863target-specific frame pointer value for the specified stack frame.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3864</p>
3865
3866<h5>Arguments:</h5>
3867
3868<p>
3869The argument to this intrinsic indicates which function to return the frame
3870pointer for. Zero indicates the calling function, one indicates its caller,
3871etc. The argument is <b>required</b> to be a constant integer value.
3872</p>
3873
3874<h5>Semantics:</h5>
3875
3876<p>
3877The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3878the frame address of the specified call frame, or zero if it cannot be
3879identified. The value returned by this intrinsic is likely to be incorrect or 0
3880for arguments other than zero, so it should only be used for debugging purposes.
3881</p>
3882
3883<p>
3884Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3885aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3886source-language caller.
3887</p>
3888</div>
3889
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3890<!-- _______________________________________________________________________ -->
3891<div class="doc_subsubsection">
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3892 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
3893</div>
3894
3895<div class="doc_text">
3896
3897<h5>Syntax:</h5>
3898<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3899 declare i8 *%llvm.stacksave()
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3900</pre>
3901
3902<h5>Overview:</h5>
3903
3904<p>
3905The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
3906the function stack, for use with <a href="#i_stackrestore">
3907<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3908features like scoped automatic variable sized arrays in C99.
3909</p>
3910
3911<h5>Semantics:</h5>
3912
3913<p>
3914This intrinsic returns a opaque pointer value that can be passed to <a
3915href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
3916<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
3917<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
3918state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
3919practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
3920that were allocated after the <tt>llvm.stacksave</tt> was executed.
3921</p>
3922
3923</div>
3924
3925<!-- _______________________________________________________________________ -->
3926<div class="doc_subsubsection">
3927 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
3928</div>
3929
3930<div class="doc_text">
3931
3932<h5>Syntax:</h5>
3933<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3934 declare void %llvm.stackrestore(i8 * %ptr)
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3935</pre>
3936
3937<h5>Overview:</h5>
3938
3939<p>
3940The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
3941the function stack to the state it was in when the corresponding <a
3942href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
3943useful for implementing language features like scoped automatic variable sized
3944arrays in C99.
3945</p>
3946
3947<h5>Semantics:</h5>
3948
3949<p>
3950See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
3951</p>
3952
3953</div>
3954
3955
3956<!-- _______________________________________________________________________ -->
3957<div class="doc_subsubsection">
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3958 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
3959</div>
3960
3961<div class="doc_text">
3962
3963<h5>Syntax:</h5>
3964<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3965 declare void %llvm.prefetch(i8 * &lt;address&gt;,
3966 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3967</pre>
3968
3969<h5>Overview:</h5>
3970
3971
3972<p>
3973The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3974a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
3975no
3976effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]3977characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3978</p>
3979
3980<h5>Arguments:</h5>
3981
3982<p>
3983<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
3984determining if the fetch should be for a read (0) or write (1), and
3985<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]3986locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3987<tt>locality</tt> arguments must be constant integers.
3988</p>
3989
3990<h5>Semantics:</h5>
3991
3992<p>
3993This intrinsic does not modify the behavior of the program. In particular,
3994prefetches cannot trap and do not produce a value. On targets that support this
3995intrinsic, the prefetch can provide hints to the processor cache for better
3996performance.
3997</p>
3998
3999</div>
4000
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4001<!-- _______________________________________________________________________ -->
4002<div class="doc_subsubsection">
4003 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4004</div>
4005
4006<div class="doc_text">
4007
4008<h5>Syntax:</h5>
4009<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4010 declare void %llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4011</pre>
4012
4013<h5>Overview:</h5>
4014
4015
4016<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4017The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4018(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4019code to simulators and other tools. The method is target specific, but it is
4020expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]4021The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnerd07c3f42005-11-15 06:07:55 +0000[diff] [blame]4022after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb3e7afd2006-03-24 07:16:10 +0000[diff] [blame]4023optimizations. The intended use is to be inserted after optimizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4024correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4025</p>
4026
4027<h5>Arguments:</h5>
4028
4029<p>
4030<tt>id</tt> is a numerical id identifying the marker.
4031</p>
4032
4033<h5>Semantics:</h5>
4034
4035<p>
4036This intrinsic does not modify the behavior of the program. Backends that do not
4037support this intrinisic may ignore it.
4038</p>
4039
4040</div>
4041
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4042<!-- _______________________________________________________________________ -->
4043<div class="doc_subsubsection">
4044 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4045</div>
4046
4047<div class="doc_text">
4048
4049<h5>Syntax:</h5>
4050<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4051 declare i64 %llvm.readcyclecounter( )
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4052</pre>
4053
4054<h5>Overview:</h5>
4055
4056
4057<p>
4058The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4059counter register (or similar low latency, high accuracy clocks) on those targets
4060that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4061As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4062should only be used for small timings.
4063</p>
4064
4065<h5>Semantics:</h5>
4066
4067<p>
4068When directly supported, reading the cycle counter should not modify any memory.
4069Implementations are allowed to either return a application specific value or a
4070system wide value. On backends without support, this is lowered to a constant 0.
4071</p>
4072
4073</div>
4074
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4075<!-- ======================================================================= -->
4076<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4077 <a name="int_libc">Standard C Library Intrinsics</a>
4078</div>
4079
4080<div class="doc_text">
4081<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4082LLVM provides intrinsics for a few important standard C library functions.
4083These intrinsics allow source-language front-ends to pass information about the
4084alignment of the pointer arguments to the code generator, providing opportunity
4085for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4086</p>
4087
4088</div>
4089
4090<!-- _______________________________________________________________________ -->
4091<div class="doc_subsubsection">
4092 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4093</div>
4094
4095<div class="doc_text">
4096
4097<h5>Syntax:</h5>
4098<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4099 declare void %llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4100 i32 &lt;len&gt;, i32 &lt;align&gt;)
4101 declare void %llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4102 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4103</pre>
4104
4105<h5>Overview:</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.
4110</p>
4111
4112<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4113Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4114intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4115</p>
4116
4117<h5>Arguments:</h5>
4118
4119<p>
4120The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4121the source. The third argument is an integer argument
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4122specifying the number of bytes to copy, and the fourth argument is the alignment
4123of the source and destination locations.
4124</p>
4125
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4126<p>
4127If 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]4128the caller guarantees that both the source and destination pointers are aligned
4129to that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4130</p>
4131
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4132<h5>Semantics:</h5>
4133
4134<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4135The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4136location to the destination location, which are not allowed to overlap. It
4137copies "len" bytes of memory over. If the argument is known to be aligned to
4138some boundary, this can be specified as the fourth argument, otherwise it should
4139be set to 0 or 1.
4140</p>
4141</div>
4142
4143
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4144<!-- _______________________________________________________________________ -->
4145<div class="doc_subsubsection">
4146 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4147</div>
4148
4149<div class="doc_text">
4150
4151<h5>Syntax:</h5>
4152<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4153 declare void %llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4154 i32 &lt;len&gt;, i32 &lt;align&gt;)
4155 declare void %llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4156 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4157</pre>
4158
4159<h5>Overview:</h5>
4160
4161<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4162The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4163location to the destination location. It is similar to the
4164'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4165</p>
4166
4167<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4168Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4169intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4170</p>
4171
4172<h5>Arguments:</h5>
4173
4174<p>
4175The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4176the source. The third argument is an integer argument
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4177specifying the number of bytes to copy, and the fourth argument is the alignment
4178of the source and destination locations.
4179</p>
4180
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4181<p>
4182If 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]4183the caller guarantees that the source and destination pointers are aligned to
4184that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4185</p>
4186
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4187<h5>Semantics:</h5>
4188
4189<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4190The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4191location to the destination location, which may overlap. It
4192copies "len" bytes of memory over. If the argument is known to be aligned to
4193some boundary, this can be specified as the fourth argument, otherwise it should
4194be set to 0 or 1.
4195</p>
4196</div>
4197
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4198
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4199<!-- _______________________________________________________________________ -->
4200<div class="doc_subsubsection">
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4201 <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4202</div>
4203
4204<div class="doc_text">
4205
4206<h5>Syntax:</h5>
4207<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4208 declare void %llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4209 i32 &lt;len&gt;, i32 &lt;align&gt;)
4210 declare void %llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4211 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4212</pre>
4213
4214<h5>Overview:</h5>
4215
4216<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4217The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4218byte value.
4219</p>
4220
4221<p>
4222Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4223does not return a value, and takes an extra alignment argument.
4224</p>
4225
4226<h5>Arguments:</h5>
4227
4228<p>
4229The first argument is a pointer to the destination to fill, the second is the
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4230byte value to fill it with, the third argument is an integer
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4231argument specifying the number of bytes to fill, and the fourth argument is the
4232known alignment of destination location.
4233</p>
4234
4235<p>
4236If 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]4237the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4238</p>
4239
4240<h5>Semantics:</h5>
4241
4242<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4243The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4244the
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4245destination location. If the argument is known to be aligned to some boundary,
4246this can be specified as the fourth argument, otherwise it should be set to 0 or
42471.
4248</p>
4249</div>
4250
4251
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4252<!-- _______________________________________________________________________ -->
4253<div class="doc_subsubsection">
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4254 <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4255</div>
4256
4257<div class="doc_text">
4258
4259<h5>Syntax:</h5>
4260<pre>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4261 declare float %llvm.sqrt.f32(float %Val)
4262 declare double %llvm.sqrt.f64(double %Val)
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4263</pre>
4264
4265<h5>Overview:</h5>
4266
4267<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4268The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4269returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4270<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4271negative numbers (which allows for better optimization).
4272</p>
4273
4274<h5>Arguments:</h5>
4275
4276<p>
4277The argument and return value are floating point numbers of the same type.
4278</p>
4279
4280<h5>Semantics:</h5>
4281
4282<p>
4283This function returns the sqrt of the specified operand if it is a positive
4284floating point number.
4285</p>
4286</div>
4287
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4288<!-- _______________________________________________________________________ -->
4289<div class="doc_subsubsection">
4290 <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4291</div>
4292
4293<div class="doc_text">
4294
4295<h5>Syntax:</h5>
4296<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4297 declare float %llvm.powi.f32(float %Val, i32 %power)
4298 declare double %llvm.powi.f64(double %Val, i32 %power)
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4299</pre>
4300
4301<h5>Overview:</h5>
4302
4303<p>
4304The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4305specified (positive or negative) power. The order of evaluation of
4306multiplications is not defined.
4307</p>
4308
4309<h5>Arguments:</h5>
4310
4311<p>
4312The second argument is an integer power, and the first is a value to raise to
4313that power.
4314</p>
4315
4316<h5>Semantics:</h5>
4317
4318<p>
4319This function returns the first value raised to the second power with an
4320unspecified sequence of rounding operations.</p>
4321</div>
4322
4323
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4324<!-- ======================================================================= -->
4325<div class="doc_subsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4326 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4327</div>
4328
4329<div class="doc_text">
4330<p>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4331LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4332These allow efficient code generation for some algorithms.
4333</p>
4334
4335</div>
4336
4337<!-- _______________________________________________________________________ -->
4338<div class="doc_subsubsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4339 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4340</div>
4341
4342<div class="doc_text">
4343
4344<h5>Syntax:</h5>
4345<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4346 declare i16 %llvm.bswap.i16(i16 &lt;id&gt;)
4347 declare i32 %llvm.bswap.i32(i32 &lt;id&gt;)
4348 declare i64 %llvm.bswap.i64(i64 &lt;id&gt;)
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4349</pre>
4350
4351<h5>Overview:</h5>
4352
4353<p>
4354The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
435564 bit quantity. These are useful for performing operations on data that is not
4356in the target's native byte order.
4357</p>
4358
4359<h5>Semantics:</h5>
4360
4361<p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4362The <tt>llvm.bswap.16</tt> intrinsic returns an i16 value that has the high
4363and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4364intrinsic returns an i32 value that has the four bytes of the input i32
4365swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
4366i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt>
4367intrinsic extends this concept to 64 bits.
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4368</p>
4369
4370</div>
4371
4372<!-- _______________________________________________________________________ -->
4373<div class="doc_subsubsection">
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4374 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4375</div>
4376
4377<div class="doc_text">
4378
4379<h5>Syntax:</h5>
4380<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4381 declare i8 %llvm.ctpop.i8 (i8 &lt;src&gt;)
4382 declare i16 %llvm.ctpop.i16(i16 &lt;src&gt;)
4383 declare i32 %llvm.ctpop.i32(i32 &lt;src&gt;)
4384 declare i64 %llvm.ctpop.i64(i64 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4385</pre>
4386
4387<h5>Overview:</h5>
4388
4389<p>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4390The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4391value.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4392</p>
4393
4394<h5>Arguments:</h5>
4395
4396<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4397The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4398integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4399</p>
4400
4401<h5>Semantics:</h5>
4402
4403<p>
4404The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4405</p>
4406</div>
4407
4408<!-- _______________________________________________________________________ -->
4409<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4410 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4411</div>
4412
4413<div class="doc_text">
4414
4415<h5>Syntax:</h5>
4416<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4417 declare i8 %llvm.ctlz.i8 (i8 &lt;src&gt;)
4418 declare i16 %llvm.ctlz.i16(i16 &lt;src&gt;)
4419 declare i32 %llvm.ctlz.i32(i32 &lt;src&gt;)
4420 declare i64 %llvm.ctlz.i64(i64 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4421</pre>
4422
4423<h5>Overview:</h5>
4424
4425<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4426The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4427leading zeros in a variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4428</p>
4429
4430<h5>Arguments:</h5>
4431
4432<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4433The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4434integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4435</p>
4436
4437<h5>Semantics:</h5>
4438
4439<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4440The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4441in 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]4442of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4443</p>
4444</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4445
4446
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4447
4448<!-- _______________________________________________________________________ -->
4449<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4450 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4451</div>
4452
4453<div class="doc_text">
4454
4455<h5>Syntax:</h5>
4456<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4457 declare i8 %llvm.cttz.i8 (i8 &lt;src&gt;)
4458 declare i16 %llvm.cttz.i16(i16 &lt;src&gt;)
4459 declare i32 %llvm.cttz.i32(i32 &lt;src&gt;)
4460 declare i64 %llvm.cttz.i64(i64 &lt;src&gt;)
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4461</pre>
4462
4463<h5>Overview:</h5>
4464
4465<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4466The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4467trailing zeros.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4468</p>
4469
4470<h5>Arguments:</h5>
4471
4472<p>
4473The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4474integer type. The return type must match the argument type.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4475</p>
4476
4477<h5>Semantics:</h5>
4478
4479<p>
4480The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4481in a variable. If the src == 0 then the result is the size in bits of the type
4482of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4483</p>
4484</div>
4485
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4486<!-- ======================================================================= -->
4487<div class="doc_subsection">
4488 <a name="int_debugger">Debugger Intrinsics</a>
4489</div>
4490
4491<div class="doc_text">
4492<p>
4493The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4494are described in the <a
4495href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4496Debugging</a> document.
4497</p>
4498</div>
4499
4500
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4501<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4502<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4503<address>
4504 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4505 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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4507 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4508
4509 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]4510 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4511 Last modified: $Date$
4512</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]4513</body>
4514</html>