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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 8cea37b79acc80644de376d4bf6d712a105442d8 / . / docs / LangRef.html
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4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
Reid Spencer3921c742004-08-26 20:44:00 +0000[diff] [blame]6 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]10 <link rel="stylesheet" href="llvm.css" type="text/css">
11</head>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]25 <li><a href="#globalvars">Global Variables</a></li>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]26 <li><a href="#functionstructure">Functions</a></li>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]27 <li><a href="#paramattrs">Parameter Attributes</a></li>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]28 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]29 </ol>
30 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]31 <li><a href="#typesystem">Type System</a>
32 <ol>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]33 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]34 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]35 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]36 </ol>
37 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]38 <li><a href="#t_derived">Derived Types</a>
39 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]40 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]41 <li><a href="#t_function">Function Type</a></li>
42 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]43 <li><a href="#t_struct">Structure Type</a></li>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]44 <li><a href="#t_pstruct">Packed Structure Type</a></li>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]45 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]46 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]47 </ol>
48 </li>
49 </ol>
50 </li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]51 <li><a href="#constants">Constants</a>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]52 <ol>
53 <li><a href="#simpleconstants">Simple Constants</a>
54 <li><a href="#aggregateconstants">Aggregate Constants</a>
55 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
56 <li><a href="#undefvalues">Undefined Values</a>
57 <li><a href="#constantexprs">Constant Expressions</a>
58 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]59 </li>
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]60 <li><a href="#othervalues">Other Values</a>
61 <ol>
62 <li><a href="#inlineasm">Inline Assembler Expressions</a>
63 </ol>
64 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]65 <li><a href="#instref">Instruction Reference</a>
66 <ol>
67 <li><a href="#terminators">Terminator Instructions</a>
68 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]69 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
70 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]71 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
72 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]73 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]74 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]75 </ol>
76 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]77 <li><a href="#binaryops">Binary Operations</a>
78 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]79 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
80 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
81 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]82 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
83 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
84 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]85 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
86 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
87 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]88 </ol>
89 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]90 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
91 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]92 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]93 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]94 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
95 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]96 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
97 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]98 </ol>
99 </li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]100 <li><a href="#vectorops">Vector Operations</a>
101 <ol>
102 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
103 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
104 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]105 </ol>
106 </li>
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]107 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]108 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]109 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
110 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
111 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]112 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
113 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
114 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]115 </ol>
116 </li>
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]117 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]118 <ol>
119 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
120 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
121 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
122 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
123 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]124 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
125 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
126 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
127 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]128 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
129 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]130 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]131 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]132 <li><a href="#otherops">Other Operations</a>
133 <ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]134 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
135 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]136 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]137 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]138 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]139 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]140 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]141 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]142 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]143 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]144 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]145 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]146 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
147 <ol>
148 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
149 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
150 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
151 </ol>
152 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]153 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
154 <ol>
155 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
156 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
157 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
158 </ol>
159 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]160 <li><a href="#int_codegen">Code Generator Intrinsics</a>
161 <ol>
162 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
163 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]164 <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
165 <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]166 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]167 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]168 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]169 </ol>
170 </li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]171 <li><a href="#int_libc">Standard C Library Intrinsics</a>
172 <ol>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]173 <li><a href="#i_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
174 <li><a href="#i_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
175 <li><a href="#i_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]176 <li><a href="#i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]177 <li><a href="#i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]178 </ol>
179 </li>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]180 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]181 <ol>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]182 <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]183 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
184 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
185 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]186 </ol>
187 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]188 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]189 </ol>
190 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]191</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]192
193<div class="doc_author">
194 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
195 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]196</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]197
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]198<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]199<div class="doc_section"> <a name="abstract">Abstract </a></div>
200<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]201
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]202<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]203<p>This document is a reference manual for the LLVM assembly language.
204LLVM is an SSA based representation that provides type safety,
205low-level operations, flexibility, and the capability of representing
206'all' high-level languages cleanly. It is the common code
207representation used throughout all phases of the LLVM compilation
208strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]209</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]210
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]211<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]212<div class="doc_section"> <a name="introduction">Introduction</a> </div>
213<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]214
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]215<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]216
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]217<p>The LLVM code representation is designed to be used in three
218different forms: as an in-memory compiler IR, as an on-disk bytecode
219representation (suitable for fast loading by a Just-In-Time compiler),
220and as a human readable assembly language representation. This allows
221LLVM to provide a powerful intermediate representation for efficient
222compiler transformations and analysis, while providing a natural means
223to debug and visualize the transformations. The three different forms
224of LLVM are all equivalent. This document describes the human readable
225representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]226
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]227<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]228while being expressive, typed, and extensible at the same time. It
229aims to be a "universal IR" of sorts, by being at a low enough level
230that high-level ideas may be cleanly mapped to it (similar to how
231microprocessors are "universal IR's", allowing many source languages to
232be mapped to them). By providing type information, LLVM can be used as
233the target of optimizations: for example, through pointer analysis, it
234can be proven that a C automatic variable is never accessed outside of
235the current function... allowing it to be promoted to a simple SSA
236value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]237
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]238</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]239
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]240<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]241<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]242
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]243<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]244
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]245<p>It is important to note that this document describes 'well formed'
246LLVM assembly language. There is a difference between what the parser
247accepts and what is considered 'well formed'. For example, the
248following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]249
250<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]251 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]252</pre>
253
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]254<p>...because the definition of <tt>%x</tt> does not dominate all of
255its uses. The LLVM infrastructure provides a verification pass that may
256be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]257automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]258the optimizer before it outputs bytecode. The violations pointed out
259by the verifier pass indicate bugs in transformation passes or input to
260the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]261
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]262<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]263
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]264<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]265<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]266<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]267
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]268<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]269
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]270<p>LLVM uses three different forms of identifiers, for different
271purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]272
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]273<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]274 <li>Named values are represented as a string of characters with a '%' prefix.
275 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
276 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
277 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]278 with quotes. In this way, anything except a <tt>&quot;</tt> character can be used
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]279 in a name.</li>
280
281 <li>Unnamed values are represented as an unsigned numeric value with a '%'
282 prefix. For example, %12, %2, %44.</li>
283
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]284 <li>Constants, which are described in a <a href="#constants">section about
285 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]286</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]287
288<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
289don't need to worry about name clashes with reserved words, and the set of
290reserved words may be expanded in the future without penalty. Additionally,
291unnamed identifiers allow a compiler to quickly come up with a temporary
292variable without having to avoid symbol table conflicts.</p>
293
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]294<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]295languages. There are keywords for different opcodes
296('<tt><a href="#i_add">add</a></tt>',
297 '<tt><a href="#i_bitcast">bitcast</a></tt>',
298 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]299href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]300and others. These reserved words cannot conflict with variable names, because
301none of them start with a '%' character.</p>
302
303<p>Here is an example of LLVM code to multiply the integer variable
304'<tt>%X</tt>' by 8:</p>
305
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]306<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]307
308<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]309 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]310</pre>
311
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]312<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]313
314<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]315 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]316</pre>
317
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]318<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]319
320<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]321 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
322 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
323 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]324</pre>
325
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]326<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
327important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]328
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]329<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]330
331 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
332 line.</li>
333
334 <li>Unnamed temporaries are created when the result of a computation is not
335 assigned to a named value.</li>
336
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]337 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]338
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]339</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]340
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]341<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]342demonstrating instructions, we will follow an instruction with a comment that
343defines the type and name of value produced. Comments are shown in italic
344text.</p>
345
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]346</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]347
348<!-- *********************************************************************** -->
349<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
350<!-- *********************************************************************** -->
351
352<!-- ======================================================================= -->
353<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
354</div>
355
356<div class="doc_text">
357
358<p>LLVM programs are composed of "Module"s, each of which is a
359translation unit of the input programs. Each module consists of
360functions, global variables, and symbol table entries. Modules may be
361combined together with the LLVM linker, which merges function (and
362global variable) definitions, resolves forward declarations, and merges
363symbol table entries. Here is an example of the "hello world" module:</p>
364
365<pre><i>; Declare the string constant as a global constant...</i>
366<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]367 href="#globalvars">constant</a> <a href="#t_array">[13 x i8 ]</a> c"hello world\0A\00" <i>; [13 x i8 ]*</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]368
369<i>; External declaration of the puts function</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]370<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]371
Chris Lattner81c01f02006-06-13 03:05:47 +0000[diff] [blame]372<i>; Global variable / Function body section separator</i>
373implementation
374
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]375<i>; Definition of main function</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]376define i32 %main() { <i>; i32()* </i>
377 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]378 %cast210 = <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]379 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* %.LC0, i64 0, i64 0 <i>; i8 *</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]380
381 <i>; Call puts function to write out the string to stdout...</i>
382 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]383 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]384 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]385 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]386
387<p>This example is made up of a <a href="#globalvars">global variable</a>
388named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
389function, and a <a href="#functionstructure">function definition</a>
390for "<tt>main</tt>".</p>
391
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]392<p>In general, a module is made up of a list of global values,
393where both functions and global variables are global values. Global values are
394represented by a pointer to a memory location (in this case, a pointer to an
395array of char, and a pointer to a function), and have one of the following <a
396href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]397
Chris Lattner81c01f02006-06-13 03:05:47 +0000[diff] [blame]398<p>Due to a limitation in the current LLVM assembly parser (it is limited by
399one-token lookahead), modules are split into two pieces by the "implementation"
400keyword. Global variable prototypes and definitions must occur before the
401keyword, and function definitions must occur after it. Function prototypes may
402occur either before or after it. In the future, the implementation keyword may
403become a noop, if the parser gets smarter.</p>
404
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsection">
409 <a name="linkage">Linkage Types</a>
410</div>
411
412<div class="doc_text">
413
414<p>
415All Global Variables and Functions have one of the following types of linkage:
416</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]417
418<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]419
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]420 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]421
422 <dd>Global values with internal linkage are only directly accessible by
423 objects in the current module. In particular, linking code into a module with
424 an internal global value may cause the internal to be renamed as necessary to
425 avoid collisions. Because the symbol is internal to the module, all
426 references can be updated. This corresponds to the notion of the
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]427 '<tt>static</tt>' keyword in C.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]428 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]429
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]430 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]431
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]432 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
433 the same name when linkage occurs. This is typically used to implement
434 inline functions, templates, or other code which must be generated in each
435 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
436 allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]437 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]438
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]439 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]440
441 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
442 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattner4887bd82007-01-14 06:51:48 +0000[diff] [blame]443 used for globals that may be emitted in multiple translation units, but that
444 are not guaranteed to be emitted into every translation unit that uses them.
445 One example of this are common globals in C, such as "<tt>int X;</tt>" at
446 global scope.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]447 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]448
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]449 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]450
451 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
452 pointer to array type. When two global variables with appending linkage are
453 linked together, the two global arrays are appended together. This is the
454 LLVM, typesafe, equivalent of having the system linker append together
455 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]456 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]457
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]458 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
459 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
460 until linked, if not linked, the symbol becomes null instead of being an
461 undefined reference.
462 </dd>
463</dl>
464
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]465 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]466
467 <dd>If none of the above identifiers are used, the global is externally
468 visible, meaning that it participates in linkage and can be used to resolve
469 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]470 </dd>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]471
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]472 <p>
473 The next two types of linkage are targeted for Microsoft Windows platform
474 only. They are designed to support importing (exporting) symbols from (to)
475 DLLs.
476 </p>
477
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]478 <dl>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]479 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
480
481 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
482 or variable via a global pointer to a pointer that is set up by the DLL
483 exporting the symbol. On Microsoft Windows targets, the pointer name is
484 formed by combining <code>_imp__</code> and the function or variable name.
485 </dd>
486
487 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
488
489 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
490 pointer to a pointer in a DLL, so that it can be referenced with the
491 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
492 name is formed by combining <code>_imp__</code> and the function or variable
493 name.
494 </dd>
495
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]496</dl>
497
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]498<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]499variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
500variable and was linked with this one, one of the two would be renamed,
501preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
502external (i.e., lacking any linkage declarations), they are accessible
Reid Spencerac8d2762007-01-05 00:59:10 +0000[diff] [blame]503outside of the current module.</p>
504<p>It is illegal for a function <i>declaration</i>
505to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]506or <tt>extern_weak</tt>.</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]507
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]508</div>
509
510<!-- ======================================================================= -->
511<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]512 <a name="callingconv">Calling Conventions</a>
513</div>
514
515<div class="doc_text">
516
517<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
518and <a href="#i_invoke">invokes</a> can all have an optional calling convention
519specified for the call. The calling convention of any pair of dynamic
520caller/callee must match, or the behavior of the program is undefined. The
521following calling conventions are supported by LLVM, and more may be added in
522the future:</p>
523
524<dl>
525 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
526
527 <dd>This calling convention (the default if no other calling convention is
528 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]529 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencerc28d2bc2006-12-31 21:30:18 +0000[diff] [blame]530 prototype and implemented declaration of the function (as does normal C).
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]531 </dd>
532
Chris Lattner5710ce92006-05-19 21:15:36 +0000[diff] [blame]533 <dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
534
535 <dd>This calling convention matches the target C calling conventions, except
536 that functions with this convention are required to take a pointer as their
537 first argument, and the return type of the function must be void. This is
538 used for C functions that return aggregates by-value. In this case, the
539 function has been transformed to take a pointer to the struct as the first
540 argument to the function. For targets where the ABI specifies specific
541 behavior for structure-return calls, the calling convention can be used to
542 distinguish between struct return functions and other functions that take a
543 pointer to a struct as the first argument.
544 </dd>
545
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]546 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
547
548 <dd>This calling convention attempts to make calls as fast as possible
549 (e.g. by passing things in registers). This calling convention allows the
550 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]551 without having to conform to an externally specified ABI. Implementations of
552 this convention should allow arbitrary tail call optimization to be supported.
553 This calling convention does not support varargs and requires the prototype of
554 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]555 </dd>
556
557 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
558
559 <dd>This calling convention attempts to make code in the caller as efficient
560 as possible under the assumption that the call is not commonly executed. As
561 such, these calls often preserve all registers so that the call does not break
562 any live ranges in the caller side. This calling convention does not support
563 varargs and requires the prototype of all callees to exactly match the
564 prototype of the function definition.
565 </dd>
566
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]567 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]568
569 <dd>Any calling convention may be specified by number, allowing
570 target-specific calling conventions to be used. Target specific calling
571 conventions start at 64.
572 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]573</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]574
575<p>More calling conventions can be added/defined on an as-needed basis, to
576support pascal conventions or any other well-known target-independent
577convention.</p>
578
579</div>
580
581<!-- ======================================================================= -->
582<div class="doc_subsection">
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame^]583 <a name="visibility">Visibility Styles</a>
584</div>
585
586<div class="doc_text">
587
588<p>
589All Global Variables and Functions have one of the following visibility styles:
590</p>
591
592<dl>
593 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
594
595 <dd>On ELF, default visibility means that the declaration is visible to other
596 modules and, in shared libraries, means that the declared entity may be
597 overridden. On Darwin, default visibility means that the declaration is
598 visible to other modules. Default visibility corresponds to "external
599 linkage" in the language.
600 </dd>
601
602 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
603
604 <dd>Two declarations of an object with hidden visibility refer to the same
605 object if they are in the same shared object. Usually, hidden visibility
606 indicates that the symbol will not be placed into the dynamic symbol table,
607 so no other module (executable or shared library) can reference it
608 directly.
609 </dd>
610
611</dl>
612
613</div>
614
615<!-- ======================================================================= -->
616<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]617 <a name="globalvars">Global Variables</a>
618</div>
619
620<div class="doc_text">
621
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]622<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]623instead of run-time. Global variables may optionally be initialized, may have
624an explicit section to be placed in, and may
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]625have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]626variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]627contents of the variable will <b>never</b> be modified (enabling better
628optimization, allowing the global data to be placed in the read-only section of
629an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]630cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]631
632<p>
633LLVM explicitly allows <em>declarations</em> of global variables to be marked
634constant, even if the final definition of the global is not. This capability
635can be used to enable slightly better optimization of the program, but requires
636the language definition to guarantee that optimizations based on the
637'constantness' are valid for the translation units that do not include the
638definition.
639</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]640
641<p>As SSA values, global variables define pointer values that are in
642scope (i.e. they dominate) all basic blocks in the program. Global
643variables always define a pointer to their "content" type because they
644describe a region of memory, and all memory objects in LLVM are
645accessed through pointers.</p>
646
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]647<p>LLVM allows an explicit section to be specified for globals. If the target
648supports it, it will emit globals to the section specified.</p>
649
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]650<p>An explicit alignment may be specified for a global. If not present, or if
651the alignment is set to zero, the alignment of the global is set by the target
652to whatever it feels convenient. If an explicit alignment is specified, the
653global is forced to have at least that much alignment. All alignments must be
654a power of 2.</p>
655
Chris Lattner68027ea2007-01-14 00:27:09 +0000[diff] [blame]656<p>For example, the following defines a global with an initializer, section,
657 and alignment:</p>
658
659<pre>
660 %G = constant float 1.0, section "foo", align 4
661</pre>
662
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]663</div>
664
665
666<!-- ======================================================================= -->
667<div class="doc_subsection">
668 <a name="functionstructure">Functions</a>
669</div>
670
671<div class="doc_text">
672
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]673<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
674an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame^]675<a href="#visibility">visibility style</a>, an optional
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]676<a href="#callingconv">calling convention</a>, a return type, an optional
677<a href="#paramattrs">parameter attribute</a> for the return type, a function
678name, a (possibly empty) argument list (each with optional
Anton Korobeynikov8cea37b2007-01-23 12:35:46 +0000[diff] [blame^]679<a href="#paramattrs">parameter attributes</a>), an optional section, an
680optional alignment, an opening curly brace, a list of basic blocks, and a
681closing curly brace.
682
683LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
684optional <a href="#linkage">linkage type</a>, an optional
685<a href="#visibility">visibility style</a>, an optional
686<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]687<a href="#paramattrs">parameter attribute</a> for the return type, a function
688name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]689
690<p>A function definition contains a list of basic blocks, forming the CFG for
691the function. Each basic block may optionally start with a label (giving the
692basic block a symbol table entry), contains a list of instructions, and ends
693with a <a href="#terminators">terminator</a> instruction (such as a branch or
694function return).</p>
695
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]696<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]697executed on entrance to the function, and it is not allowed to have predecessor
698basic blocks (i.e. there can not be any branches to the entry block of a
699function). Because the block can have no predecessors, it also cannot have any
700<a href="#i_phi">PHI nodes</a>.</p>
701
702<p>LLVM functions are identified by their name and type signature. Hence, two
703functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]704considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]705appropriately.</p>
706
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]707<p>LLVM allows an explicit section to be specified for functions. If the target
708supports it, it will emit functions to the section specified.</p>
709
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]710<p>An explicit alignment may be specified for a function. If not present, or if
711the alignment is set to zero, the alignment of the function is set by the target
712to whatever it feels convenient. If an explicit alignment is specified, the
713function is forced to have at least that much alignment. All alignments must be
714a power of 2.</p>
715
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]716</div>
717
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]718<!-- ======================================================================= -->
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]719<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
720<div class="doc_text">
721 <p>The return type and each parameter of a function type may have a set of
722 <i>parameter attributes</i> associated with them. Parameter attributes are
723 used to communicate additional information about the result or parameters of
724 a function. Parameter attributes are considered to be part of the function
725 type so two functions types that differ only by the parameter attributes
726 are different function types.</p>
727
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]728 <p>Parameter attributes are simple keywords that follow the type specified. If
729 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]730 example:</p><pre>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]731 %someFunc = i16 (i8 sext %someParam) zext
732 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]733 <p>Note that the two function types above are unique because the parameter has
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]734 a different attribute (sext in the first one, zext in the second). Also note
735 that the attribute for the function result (zext) comes immediately after the
736 argument list.</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]737
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]738 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]739 <dl>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]740 <dt><tt>zext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]741 <dd>This indicates that the parameter should be zero extended just before
742 a call to this function.</dd>
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]743 <dt><tt>sext</tt></dt>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]744 <dd>This indicates that the parameter should be sign extended just before
745 a call to this function.</dd>
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]746 </dl>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]747
748 <p>The current motivation for parameter attributes is to enable the sign and
749 zero extend information necessary for the C calling convention to be passed
Reid Spencer950e9f82007-01-15 18:27:39 +0000[diff] [blame]750 from the front end to LLVM. The <tt>zext</tt> and <tt>sext</tt> attributes
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]751 are used by the code generator to perform the required extension. However,
752 parameter attributes are an orthogonal feature to calling conventions and
753 may be used for other purposes in the future.</p>
754</div>
755
756<!-- ======================================================================= -->
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]757<div class="doc_subsection">
Chris Lattner1eeeb0c2006-04-08 04:40:53 +0000[diff] [blame]758 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]759</div>
760
761<div class="doc_text">
762<p>
763Modules may contain "module-level inline asm" blocks, which corresponds to the
764GCC "file scope inline asm" blocks. These blocks are internally concatenated by
765LLVM and treated as a single unit, but may be separated in the .ll file if
766desired. The syntax is very simple:
767</p>
768
769<div class="doc_code"><pre>
Chris Lattner52599e12006-01-24 00:37:20 +0000[diff] [blame]770 module asm "inline asm code goes here"
771 module asm "more can go here"
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]772</pre></div>
773
774<p>The strings can contain any character by escaping non-printable characters.
775 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
776 for the number.
777</p>
778
779<p>
780 The inline asm code is simply printed to the machine code .s file when
781 assembly code is generated.
782</p>
783</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]784
785
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]786<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]787<div class="doc_section"> <a name="typesystem">Type System</a> </div>
788<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]789
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]790<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]791
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]792<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]793intermediate representation. Being typed enables a number of
794optimizations to be performed on the IR directly, without having to do
795extra analyses on the side before the transformation. A strong type
796system makes it easier to read the generated code and enables novel
797analyses and transformations that are not feasible to perform on normal
798three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]799
800</div>
801
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]802<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]803<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]804<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]805<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]806system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]807
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]808<table class="layout">
809 <tr class="layout">
810 <td class="left">
811 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]812 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]813 <tr><th>Type</th><th>Description</th></tr>
814 <tr><td><tt>void</tt></td><td>No value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]815 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
816 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]817 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]818 <tr><td><tt>label</tt></td><td>Branch destination</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 <td class="right">
823 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]824 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]825 <tr><th>Type</th><th>Description</th></tr>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]826 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]827 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
828 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]829 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]830 </tbody>
831 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]832 </td>
833 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]834</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]835</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]836
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]837<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]838<div class="doc_subsubsection"> <a name="t_classifications">Type
839Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]840<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]841<p>These different primitive types fall into a few useful
842classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]843
844<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]845 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]846 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]847 <tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]848 <td><a name="t_integer">integer</a></td>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]849 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]850 </tr>
851 <tr>
852 <td><a name="t_floating">floating point</a></td>
853 <td><tt>float, double</tt></td>
854 </tr>
855 <tr>
856 <td><a name="t_firstclass">first class</a></td>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]857 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]858 <a href="#t_pointer">pointer</a>,<a href="#t_packed">packed</a></tt>
859 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]860 </tr>
861 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]862</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]863
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]864<p>The <a href="#t_firstclass">first class</a> types are perhaps the
865most important. Values of these types are the only ones which can be
866produced by instructions, passed as arguments, or used as operands to
867instructions. This means that all structures and arrays must be
868manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]869</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]870
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]871<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]872<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]873
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]874<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]875
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]876<p>The real power in LLVM comes from the derived types in the system.
877This is what allows a programmer to represent arrays, functions,
878pointers, and other useful types. Note that these derived types may be
879recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]880
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]881</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]882
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]883<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]884<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]885
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]886<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]887
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]888<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]889
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]890<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]891sequentially in memory. The array type requires a size (number of
892elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]893
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]894<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]895
896<pre>
897 [&lt;# elements&gt; x &lt;elementtype&gt;]
898</pre>
899
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]900<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]901be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]902
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]903<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]904<table class="layout">
905 <tr class="layout">
906 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]907 <tt>[40 x i32 ]</tt><br/>
908 <tt>[41 x i32 ]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]909 <tt>[40 x i8]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]910 </td>
911 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]912 Array of 40 32-bit integer values.<br/>
913 Array of 41 32-bit integer values.<br/>
914 Array of 40 8-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]915 </td>
916 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]917</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]918<p>Here are some examples of multidimensional arrays:</p>
919<table class="layout">
920 <tr class="layout">
921 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]922 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]923 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]924 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]925 </td>
926 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]927 3x4 array of 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]928 12x10 array of single precision floating point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]929 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]930 </td>
931 </tr>
932</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]933
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]934<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
935length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]936LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
937As a special case, however, zero length arrays are recognized to be variable
938length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]939type "{ i32, [0 x float]}", for example.</p>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]940
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]941</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]942
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]943<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]944<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]945<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]946<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]947<p>The function type can be thought of as a function signature. It
948consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]949Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]950(which are structures of pointers to functions), for indirect function
951calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]952<p>
953The return type of a function type cannot be an aggregate type.
954</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]955<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]956<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]957<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]958specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]959which indicates that the function takes a variable number of arguments.
960Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]961 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]962<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]963<table class="layout">
964 <tr class="layout">
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]965 <td class="left"><tt>i32 (i32)</tt></td>
966 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]967 </td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]968 </tr><tr class="layout">
Reid Spencer7bf214d2007-01-15 18:28:34 +0000[diff] [blame]969 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencerf17a0b72006-12-31 07:20:23 +0000[diff] [blame]970 </tt></td>
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]971 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
972 an <tt>i16</tt> that should be sign extended and a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]973 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]974 <tt>float</tt>.
975 </td>
976 </tr><tr class="layout">
977 <td class="left"><tt>i32 (i8*, ...)</tt></td>
978 <td class="left">A vararg function that takes at least one
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]979 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer92f82302006-12-31 07:18:34 +0000[diff] [blame]980 which returns an integer. This is the signature for <tt>printf</tt> in
981 LLVM.
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]982 </td>
983 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]984</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]985
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]986</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]987<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]988<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]989<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]990<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]991<p>The structure type is used to represent a collection of data members
992together in memory. The packing of the field types is defined to match
993the ABI of the underlying processor. The elements of a structure may
994be any type that has a size.</p>
995<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
996and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
997field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
998instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]999<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1000<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1001<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1002<table class="layout">
1003 <tr class="layout">
1004 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1005 <tt>{ i32, i32, i32 }</tt><br/>
1006 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1007 </td>
1008 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1009 a triple of three <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1010 A pair, where the first element is a <tt>float</tt> and the second element
1011 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]1012 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1013 </td>
1014 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1015</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1016</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1017
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1018<!-- _______________________________________________________________________ -->
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1019<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1020</div>
1021<div class="doc_text">
1022<h5>Overview:</h5>
1023<p>The packed structure type is used to represent a collection of data members
1024together in memory. There is no padding between fields. Further, the alignment
1025of a packed structure is 1 byte. The elements of a packed structure may
1026be any type that has a size.</p>
1027<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1028and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1029field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1030instruction.</p>
1031<h5>Syntax:</h5>
1032<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1033<h5>Examples:</h5>
1034<table class="layout">
1035 <tr class="layout">
1036 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1037 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1038 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1039 </td>
1040 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1041 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1042 A pair, where the first element is a <tt>float</tt> and the second element
1043 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]1044 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth75e10682006-12-08 17:13:00 +0000[diff] [blame]1045 </td>
1046 </tr>
1047</table>
1048</div>
1049
1050<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1051<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1052<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1053<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1054<p>As in many languages, the pointer type represents a pointer or
1055reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1056<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1057<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1058<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1059<table class="layout">
1060 <tr class="layout">
1061 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1062 <tt>[4x i32]*</tt><br/>
1063 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1064 </td>
1065 <td class="left">
1066 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]1067 four <tt>i32</tt> values<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1068 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1069 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1070 <tt>i32</tt>.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1071 </td>
1072 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1073</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1074</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1075
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1076<!-- _______________________________________________________________________ -->
1077<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1078<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1079
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1080<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1081
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1082<p>A packed type is a simple derived type that represents a vector
1083of elements. Packed types are used when multiple primitive data
1084are operated in parallel using a single instruction (SIMD).
1085A packed type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]1086elements) and an underlying primitive data type. Vectors must have a power
1087of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1088considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1089
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1090<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1091
1092<pre>
1093 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1094</pre>
1095
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1096<p>The number of elements is a constant integer value; elementtype may
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1097be any integer or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1098
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1099<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1100
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1101<table class="layout">
1102 <tr class="layout">
1103 <td class="left">
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1104 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1105 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1106 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1107 </td>
1108 <td class="left">
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1109 Packed vector of 4 32-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1110 Packed vector of 8 floating-point values.<br/>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1111 Packed vector of 2 64-bit integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]1112 </td>
1113 </tr>
1114</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1115</div>
1116
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1117<!-- _______________________________________________________________________ -->
1118<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1119<div class="doc_text">
1120
1121<h5>Overview:</h5>
1122
1123<p>Opaque types are used to represent unknown types in the system. This
1124corresponds (for example) to the C notion of a foward declared structure type.
1125In LLVM, opaque types can eventually be resolved to any type (not just a
1126structure type).</p>
1127
1128<h5>Syntax:</h5>
1129
1130<pre>
1131 opaque
1132</pre>
1133
1134<h5>Examples:</h5>
1135
1136<table class="layout">
1137 <tr class="layout">
1138 <td class="left">
1139 <tt>opaque</tt>
1140 </td>
1141 <td class="left">
1142 An opaque type.<br/>
1143 </td>
1144 </tr>
1145</table>
1146</div>
1147
1148
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1149<!-- *********************************************************************** -->
1150<div class="doc_section"> <a name="constants">Constants</a> </div>
1151<!-- *********************************************************************** -->
1152
1153<div class="doc_text">
1154
1155<p>LLVM has several different basic types of constants. This section describes
1156them all and their syntax.</p>
1157
1158</div>
1159
1160<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1161<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1162
1163<div class="doc_text">
1164
1165<dl>
1166 <dt><b>Boolean constants</b></dt>
1167
1168 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1169 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1170 </dd>
1171
1172 <dt><b>Integer constants</b></dt>
1173
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1174 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1175 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1176 integer types.
1177 </dd>
1178
1179 <dt><b>Floating point constants</b></dt>
1180
1181 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1182 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1183 notation (see below). Floating point constants must have a <a
1184 href="#t_floating">floating point</a> type. </dd>
1185
1186 <dt><b>Null pointer constants</b></dt>
1187
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1188 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1189 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1190
1191</dl>
1192
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1193<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1194of floating point constants. For example, the form '<tt>double
11950x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
11964.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1197(and the only time that they are generated by the disassembler) is when a
1198floating point constant must be emitted but it cannot be represented as a
1199decimal floating point number. For example, NaN's, infinities, and other
1200special values are represented in their IEEE hexadecimal format so that
1201assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1202
1203</div>
1204
1205<!-- ======================================================================= -->
1206<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1207</div>
1208
1209<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1210<p>Aggregate constants arise from aggregation of simple constants
1211and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1212
1213<dl>
1214 <dt><b>Structure constants</b></dt>
1215
1216 <dd>Structure constants are represented with notation similar to structure
1217 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1218 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1219 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]1220 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1221 types of elements must match those specified by the type.
1222 </dd>
1223
1224 <dt><b>Array constants</b></dt>
1225
1226 <dd>Array constants are represented with notation similar to array type
1227 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1228 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1229 constants must have <a href="#t_array">array type</a>, and the number and
1230 types of elements must match those specified by the type.
1231 </dd>
1232
1233 <dt><b>Packed constants</b></dt>
1234
1235 <dd>Packed constants are represented with notation similar to packed type
1236 definitions (a comma separated list of elements, surrounded by
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1237 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1238 i32 11, i32 74, i32 100 &gt;</tt>". Packed constants must have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1239 href="#t_packed">packed type</a>, and the number and types of elements must
1240 match those specified by the type.
1241 </dd>
1242
1243 <dt><b>Zero initialization</b></dt>
1244
1245 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1246 value to zero of <em>any</em> type, including scalar and aggregate types.
1247 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]1248 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1249 initializers.
1250 </dd>
1251</dl>
1252
1253</div>
1254
1255<!-- ======================================================================= -->
1256<div class="doc_subsection">
1257 <a name="globalconstants">Global Variable and Function Addresses</a>
1258</div>
1259
1260<div class="doc_text">
1261
1262<p>The addresses of <a href="#globalvars">global variables</a> and <a
1263href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1264constants. These constants are explicitly referenced when the <a
1265href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1266href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1267file:</p>
1268
1269<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1270 %X = global i32 17
1271 %Y = global i32 42
1272 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1273</pre>
1274
1275</div>
1276
1277<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1278<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1279<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1280 <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]1281 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1282 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1283
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1284 <p>Undefined values indicate to the compiler that the program is well defined
1285 no matter what value is used, giving the compiler more freedom to optimize.
1286 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1287</div>
1288
1289<!-- ======================================================================= -->
1290<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1291</div>
1292
1293<div class="doc_text">
1294
1295<p>Constant expressions are used to allow expressions involving other constants
1296to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1297href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1298that does not have side effects (e.g. load and call are not supported). The
1299following is the syntax for constant expressions:</p>
1300
1301<dl>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1302 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1303 <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]1304 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1305
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1306 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1307 <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]1308 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]1309
1310 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1311 <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]1312 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]1313
1314 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1315 <dd>Truncate a floating point constant to another floating point type. The
1316 size of CST must be larger than the size of TYPE. Both types must be
1317 floating point.</dd>
1318
1319 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1320 <dd>Floating point extend a constant to another type. The size of CST must be
1321 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1322
1323 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1324 <dd>Convert a floating point constant to the corresponding unsigned integer
1325 constant. TYPE must be an integer type. CST must be floating point. If the
1326 value won't fit in the integer type, the results are undefined.</dd>
1327
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1328 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1329 <dd>Convert a floating point constant to the corresponding signed integer
1330 constant. TYPE must be an integer type. CST must be floating point. If the
1331 value won't fit in the integer type, the results are undefined.</dd>
1332
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1333 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1334 <dd>Convert an unsigned integer constant to the corresponding floating point
1335 constant. TYPE must be floating point. CST must be of integer type. If the
1336 value won't fit in the floating point type, the results are undefined.</dd>
1337
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1338 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1339 <dd>Convert a signed integer constant to the corresponding floating point
1340 constant. TYPE must be floating point. CST must be of integer type. If the
1341 value won't fit in the floating point type, the results are undefined.</dd>
1342
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1343 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1344 <dd>Convert a pointer typed constant to the corresponding integer constant
1345 TYPE must be an integer type. CST must be of pointer type. The CST value is
1346 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1347
1348 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1349 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1350 pointer type. CST must be of integer type. The CST value is zero extended,
1351 truncated, or unchanged to make it fit in a pointer size. This one is
1352 <i>really</i> dangerous!</dd>
1353
1354 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1355 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1356 identical (same number of bits). The conversion is done as if the CST value
1357 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]1358 with this operator, just the type. This can be used for conversion of
1359 packed types to any other type, as long as they have the same bit width. For
1360 pointers it is only valid to cast to another pointer type.
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1361 </dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1362
1363 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1364
1365 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1366 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1367 instruction, the index list may have zero or more indexes, which are required
1368 to make sense for the type of "CSTPTR".</dd>
1369
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1370 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1371
1372 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1373 constants.</dd>
1374
1375 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1376 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1377
1378 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1379 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1380
1381 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1382
1383 <dd>Perform the <a href="#i_extractelement">extractelement
1384 operation</a> on constants.
1385
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1386 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1387
1388 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1389 operation</a> on constants.</dd>
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1390
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1391
1392 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1393
1394 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer01c42592006-12-04 19:23:19 +0000[diff] [blame]1395 operation</a> on constants.</dd>
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1396
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1397 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1398
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1399 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1400 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1401 binary</a> operations. The constraints on operands are the same as those for
1402 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1403 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1404</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1405</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1406
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1407<!-- *********************************************************************** -->
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1408<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1409<!-- *********************************************************************** -->
1410
1411<!-- ======================================================================= -->
1412<div class="doc_subsection">
1413<a name="inlineasm">Inline Assembler Expressions</a>
1414</div>
1415
1416<div class="doc_text">
1417
1418<p>
1419LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1420Module-Level Inline Assembly</a>) through the use of a special value. This
1421value represents the inline assembler as a string (containing the instructions
1422to emit), a list of operand constraints (stored as a string), and a flag that
1423indicates whether or not the inline asm expression has side effects. An example
1424inline assembler expression is:
1425</p>
1426
1427<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1428 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1429</pre>
1430
1431<p>
1432Inline assembler expressions may <b>only</b> be used as the callee operand of
1433a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1434</p>
1435
1436<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1437 %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]1438</pre>
1439
1440<p>
1441Inline asms with side effects not visible in the constraint list must be marked
1442as having side effects. This is done through the use of the
1443'<tt>sideeffect</tt>' keyword, like so:
1444</p>
1445
1446<pre>
1447 call void asm sideeffect "eieio", ""()
1448</pre>
1449
1450<p>TODO: The format of the asm and constraints string still need to be
1451documented here. Constraints on what can be done (e.g. duplication, moving, etc
1452need to be documented).
1453</p>
1454
1455</div>
1456
1457<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1458<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1459<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1460
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1461<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1462
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1463<p>The LLVM instruction set consists of several different
1464classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1465instructions</a>, <a href="#binaryops">binary instructions</a>,
1466<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1467 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1468instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1469
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1470</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1471
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1472<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1473<div class="doc_subsection"> <a name="terminators">Terminator
1474Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1475
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1476<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1477
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1478<p>As mentioned <a href="#functionstructure">previously</a>, every
1479basic block in a program ends with a "Terminator" instruction, which
1480indicates which block should be executed after the current block is
1481finished. These terminator instructions typically yield a '<tt>void</tt>'
1482value: they produce control flow, not values (the one exception being
1483the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1484<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1485 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1486instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1487the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1488 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1489 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1490
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1491</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1492
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1493<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1494<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1495Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1496<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1497<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1498<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]1499 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1500</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1501<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1502<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1503value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1504<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1505returns a value and then causes control flow, and one that just causes
1506control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1507<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1508<p>The '<tt>ret</tt>' instruction may return any '<a
1509 href="#t_firstclass">first class</a>' type. Notice that a function is
1510not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1511instruction inside of the function that returns a value that does not
1512match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1513<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1514<p>When the '<tt>ret</tt>' instruction is executed, control flow
1515returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1516 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1517the instruction after the call. If the caller was an "<a
1518 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1519at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1520returns a value, that value shall set the call or invoke instruction's
1521return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1522<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1523<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1524 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1525</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1526</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1527<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1528<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1529<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1530<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1531<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]1532</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1533<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1534<p>The '<tt>br</tt>' instruction is used to cause control flow to
1535transfer to a different basic block in the current function. There are
1536two forms of this instruction, corresponding to a conditional branch
1537and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1538<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1539<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1540single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1541unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1542value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1543<h5>Semantics:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1544<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1545argument is evaluated. If the value is <tt>true</tt>, control flows
1546to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1547control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1548<h5>Example:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1549<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]1550 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]1551</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1552<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1553<div class="doc_subsubsection">
1554 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1555</div>
1556
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1557<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1558<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1559
1560<pre>
1561 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1562</pre>
1563
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1564<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1565
1566<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1567several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1568instruction, allowing a branch to occur to one of many possible
1569destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1570
1571
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1572<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1573
1574<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1575comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1576an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1577table is not allowed to contain duplicate constant entries.</p>
1578
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1579<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1580
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1581<p>The <tt>switch</tt> instruction specifies a table of values and
1582destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1583table is searched for the given value. If the value is found, control flow is
1584transfered to the corresponding destination; otherwise, control flow is
1585transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1586
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1587<h5>Implementation:</h5>
1588
1589<p>Depending on properties of the target machine and the particular
1590<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1591ways. For example, it could be generated as a series of chained conditional
1592branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1593
1594<h5>Example:</h5>
1595
1596<pre>
1597 <i>; Emulate a conditional br instruction</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]1598 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1599 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1600
1601 <i>; Emulate an unconditional br instruction</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1602 switch i32 0, label %dest [ ]
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1603
1604 <i>; Implement a jump table:</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1605 switch i32 %val, label %otherwise [ i32 0, label %onzero
1606 i32 1, label %onone
1607 i32 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1608</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1609</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1610
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1611<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1612<div class="doc_subsubsection">
1613 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1614</div>
1615
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1616<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1617
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1618<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1619
1620<pre>
1621 &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]1622 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1623</pre>
1624
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1625<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1626
1627<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1628function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1629'<tt>normal</tt>' label or the
1630'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1631"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1632"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1633href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1634continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1635
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1636<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1637
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1638<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1639
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1640<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1641 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1642 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1643 convention</a> the call should use. If none is specified, the call defaults
1644 to using C calling conventions.
1645 </li>
1646 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1647 function value being invoked. In most cases, this is a direct function
1648 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1649 an arbitrary pointer to function value.
1650 </li>
1651
1652 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1653 function to be invoked. </li>
1654
1655 <li>'<tt>function args</tt>': argument list whose types match the function
1656 signature argument types. If the function signature indicates the function
1657 accepts a variable number of arguments, the extra arguments can be
1658 specified. </li>
1659
1660 <li>'<tt>normal label</tt>': the label reached when the called function
1661 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1662
1663 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1664 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1665
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1666</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1667
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1668<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1669
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1670<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1671href="#i_call">call</a></tt>' instruction in most regards. The primary
1672difference is that it establishes an association with a label, which is used by
1673the runtime library to unwind the stack.</p>
1674
1675<p>This instruction is used in languages with destructors to ensure that proper
1676cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1677exception. Additionally, this is important for implementation of
1678'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1679
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1680<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1681<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1682 %retval = invoke i32 %Test(i32 15) to label %Continue
1683 unwind label %TestCleanup <i>; {i32}:retval set</i>
1684 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1685 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1686</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1687</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1688
1689
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1690<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1691
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1692<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1693Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1694
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1695<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1696
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1697<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1698<pre>
1699 unwind
1700</pre>
1701
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1702<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1703
1704<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1705at the first callee in the dynamic call stack which used an <a
1706href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1707primarily used to implement exception handling.</p>
1708
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1709<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1710
1711<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1712immediately halt. The dynamic call stack is then searched for the first <a
1713href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1714execution continues at the "exceptional" destination block specified by the
1715<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1716dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1717</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1718
1719<!-- _______________________________________________________________________ -->
1720
1721<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1722Instruction</a> </div>
1723
1724<div class="doc_text">
1725
1726<h5>Syntax:</h5>
1727<pre>
1728 unreachable
1729</pre>
1730
1731<h5>Overview:</h5>
1732
1733<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1734instruction is used to inform the optimizer that a particular portion of the
1735code is not reachable. This can be used to indicate that the code after a
1736no-return function cannot be reached, and other facts.</p>
1737
1738<h5>Semantics:</h5>
1739
1740<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1741</div>
1742
1743
1744
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_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1747<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1748<p>Binary operators are used to do most of the computation in a
1749program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1750produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1751multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1752The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1753necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1754<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1755</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1756<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1757<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1758Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1759<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1760<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1761<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]1762</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1763<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1764<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1765<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1766<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1767 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1768 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1769Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1770<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1771<p>The value produced is the integer or floating point sum of the two
1772operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1773<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1774<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]1775</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1776</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1777<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1778<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1779Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1780<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1781<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1782<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]1783</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1784<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1785<p>The '<tt>sub</tt>' instruction returns the difference of its two
1786operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1787<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1788instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1789<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1790<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1791 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1792values.
1793This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1794Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1795<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1796<p>The value produced is the integer or floating point difference of
1797the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1798<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1799<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1800 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1801</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1802</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1803<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1804<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1805Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1806<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1807<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1808<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]1809</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1810<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1811<p>The '<tt>mul</tt>' instruction returns the product of its two
1812operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1813<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1814<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1815 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1816values.
1817This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1818Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1819<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1820<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1821two operands.</p>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]1822<p>Because the operands are the same width, the result of an integer
1823multiplication is the same whether the operands should be deemed unsigned or
1824signed.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1825<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1826<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]1827</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1828</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1829<!-- _______________________________________________________________________ -->
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1830<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1831</a></div>
1832<div class="doc_text">
1833<h5>Syntax:</h5>
1834<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1835</pre>
1836<h5>Overview:</h5>
1837<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1838operands.</p>
1839<h5>Arguments:</h5>
1840<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1841<a href="#t_integer">integer</a> values. Both arguments must have identical
1842types. This instruction can also take <a href="#t_packed">packed</a> versions
1843of the values in which case the elements must be integers.</p>
1844<h5>Semantics:</h5>
1845<p>The value produced is the unsigned integer quotient of the two operands. This
1846instruction always performs an unsigned division operation, regardless of
1847whether the arguments are unsigned or not.</p>
1848<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1849<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]1850</pre>
1851</div>
1852<!-- _______________________________________________________________________ -->
1853<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1854</a> </div>
1855<div class="doc_text">
1856<h5>Syntax:</h5>
1857<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1858</pre>
1859<h5>Overview:</h5>
1860<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1861operands.</p>
1862<h5>Arguments:</h5>
1863<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1864<a href="#t_integer">integer</a> values. Both arguments must have identical
1865types. This instruction can also take <a href="#t_packed">packed</a> versions
1866of the values in which case the elements must be integers.</p>
1867<h5>Semantics:</h5>
1868<p>The value produced is the signed integer quotient of the two operands. This
1869instruction always performs a signed division operation, regardless of whether
1870the arguments are signed or not.</p>
1871<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1872<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]1873</pre>
1874</div>
1875<!-- _______________________________________________________________________ -->
1876<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1877Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1878<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1879<h5>Syntax:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1880<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]1881</pre>
1882<h5>Overview:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1883<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1884operands.</p>
1885<h5>Arguments:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1886<p>The two arguments to the '<tt>div</tt>' instruction must be
1887<a href="#t_floating">floating point</a> values. Both arguments must have
1888identical types. This instruction can also take <a href="#t_packed">packed</a>
1889versions of the values in which case the elements must be floating point.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1890<h5>Semantics:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1891<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1892<h5>Example:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1893<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]1894</pre>
1895</div>
1896<!-- _______________________________________________________________________ -->
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1897<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1898</div>
1899<div class="doc_text">
1900<h5>Syntax:</h5>
1901<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1902</pre>
1903<h5>Overview:</h5>
1904<p>The '<tt>urem</tt>' instruction returns the remainder from the
1905unsigned division of its two arguments.</p>
1906<h5>Arguments:</h5>
1907<p>The two arguments to the '<tt>urem</tt>' instruction must be
1908<a href="#t_integer">integer</a> values. Both arguments must have identical
1909types.</p>
1910<h5>Semantics:</h5>
1911<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1912This instruction always performs an unsigned division to get the remainder,
1913regardless of whether the arguments are unsigned or not.</p>
1914<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1915<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]1916</pre>
1917
1918</div>
1919<!-- _______________________________________________________________________ -->
1920<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1921Instruction</a> </div>
1922<div class="doc_text">
1923<h5>Syntax:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1924<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]1925</pre>
1926<h5>Overview:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1927<p>The '<tt>srem</tt>' instruction returns the remainder from the
1928signed division of its two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1929<h5>Arguments:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1930<p>The two arguments to the '<tt>srem</tt>' instruction must be
1931<a href="#t_integer">integer</a> values. Both arguments must have identical
1932types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1933<h5>Semantics:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1934<p>This instruction returns the <i>remainder</i> of a division (where the result
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1935has the same sign as the divisor), not the <i>modulus</i> (where the
1936result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1937information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1938 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1939Math Forum</a>.</p>
1940<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]1941<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]1942</pre>
1943
1944</div>
1945<!-- _______________________________________________________________________ -->
1946<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
1947Instruction</a> </div>
1948<div class="doc_text">
1949<h5>Syntax:</h5>
1950<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1951</pre>
1952<h5>Overview:</h5>
1953<p>The '<tt>frem</tt>' instruction returns the remainder from the
1954division of its two operands.</p>
1955<h5>Arguments:</h5>
1956<p>The two arguments to the '<tt>frem</tt>' instruction must be
1957<a href="#t_floating">floating point</a> values. Both arguments must have
1958identical types.</p>
1959<h5>Semantics:</h5>
1960<p>This instruction returns the <i>remainder</i> of a division.</p>
1961<h5>Example:</h5>
1962<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]1963</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1964</div>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]1965
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1966<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1967<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1968Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1969<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1970<p>Bitwise binary operators are used to do various forms of
1971bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1972instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1973instructions. They require two operands, execute an operation on them,
1974and produce a single value. The resulting value of the bitwise binary
1975operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1976</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1977<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1978<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1979Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1980<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1981<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1982<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]1983</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1984<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1985<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1986its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1987<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1988<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]1989 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1990identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1991<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1992<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1993<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1994<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1995<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1996 <tbody>
1997 <tr>
1998 <td>In0</td>
1999 <td>In1</td>
2000 <td>Out</td>
2001 </tr>
2002 <tr>
2003 <td>0</td>
2004 <td>0</td>
2005 <td>0</td>
2006 </tr>
2007 <tr>
2008 <td>0</td>
2009 <td>1</td>
2010 <td>0</td>
2011 </tr>
2012 <tr>
2013 <td>1</td>
2014 <td>0</td>
2015 <td>0</td>
2016 </tr>
2017 <tr>
2018 <td>1</td>
2019 <td>1</td>
2020 <td>1</td>
2021 </tr>
2022 </tbody>
2023</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2024</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2025<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2026<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2027 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2028 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2029</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2030</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2031<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2032<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2033<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2034<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2035<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]2036</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2037<h5>Overview:</h5>
2038<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2039or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2040<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2041<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2042 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2043identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2044<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2045<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2046<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2047<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2048<table border="1" cellspacing="0" cellpadding="4">
2049 <tbody>
2050 <tr>
2051 <td>In0</td>
2052 <td>In1</td>
2053 <td>Out</td>
2054 </tr>
2055 <tr>
2056 <td>0</td>
2057 <td>0</td>
2058 <td>0</td>
2059 </tr>
2060 <tr>
2061 <td>0</td>
2062 <td>1</td>
2063 <td>1</td>
2064 </tr>
2065 <tr>
2066 <td>1</td>
2067 <td>0</td>
2068 <td>1</td>
2069 </tr>
2070 <tr>
2071 <td>1</td>
2072 <td>1</td>
2073 <td>1</td>
2074 </tr>
2075 </tbody>
2076</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2077</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2078<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2079<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2080 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2081 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2082</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2083</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2084<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2085<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2086Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2087<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2088<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2089<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]2090</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2091<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2092<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2093or of its two operands. The <tt>xor</tt> is used to implement the
2094"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2095<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2096<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2097 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2098identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2099<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2100<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2101<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2102<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2103<table border="1" cellspacing="0" cellpadding="4">
2104 <tbody>
2105 <tr>
2106 <td>In0</td>
2107 <td>In1</td>
2108 <td>Out</td>
2109 </tr>
2110 <tr>
2111 <td>0</td>
2112 <td>0</td>
2113 <td>0</td>
2114 </tr>
2115 <tr>
2116 <td>0</td>
2117 <td>1</td>
2118 <td>1</td>
2119 </tr>
2120 <tr>
2121 <td>1</td>
2122 <td>0</td>
2123 <td>1</td>
2124 </tr>
2125 <tr>
2126 <td>1</td>
2127 <td>1</td>
2128 <td>0</td>
2129 </tr>
2130 </tbody>
2131</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2132</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2133<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2134<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2135<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2136 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2137 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2138 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2139</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2140</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2141<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2142<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2143Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2144<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2145<h5>Syntax:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2146<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2147</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2148<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2149<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2150the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2151<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2152<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2153 href="#t_integer">integer</a> type. The second argument must be an '<tt>i8</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2154type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2155<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2156<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2157<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2158<pre> &lt;result&gt; = shl i32 4, i8 %var <i>; yields {i32}:result = 4 &lt;&lt; %var</i>
2159 &lt;result&gt; = shl i32 4, i8 2 <i>; yields {i32}:result = 16</i>
2160 &lt;result&gt; = shl i32 1, i8 10 <i>; yields {i32}:result = 1024</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2161</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2162</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2163<!-- _______________________________________________________________________ -->
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2164<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2165Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2166<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2167<h5>Syntax:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2168<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2169</pre>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2170
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2171<h5>Overview:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2172<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2173operand shifted to the right a specified number of bits.</p>
2174
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2175<h5>Arguments:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2176<p>The first argument to the '<tt>lshr</tt>' instruction must be an <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2177 href="#t_integer">integer</a> type. The second argument must be an '<tt>i8</tt>' type.</p>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2178
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2179<h5>Semantics:</h5>
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]2180<p>This instruction always performs a logical shift right operation. The
2181<tt>var2</tt> most significant bits will be filled with zero bits after the
2182shift.</p>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2183
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2184<h5>Example:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2185<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2186 &lt;result&gt; = lshr i32 4, i8 1 <i>; yields {i32}:result = 2</i>
2187 &lt;result&gt; = lshr i32 4, i8 2 <i>; yields {i32}:result = 1</i>
2188 &lt;result&gt; = lshr i8 4, i8 3 <i>; yields {i8 }:result = 0</i>
2189 &lt;result&gt; = lshr i8 -2, i8 1 <i>; yields {i8 }:result = 0x7FFFFFFF </i>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2190</pre>
2191</div>
2192
2193<!-- ======================================================================= -->
2194<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2195Instruction</a> </div>
2196<div class="doc_text">
2197
2198<h5>Syntax:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2199<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2200</pre>
2201
2202<h5>Overview:</h5>
2203<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2204operand shifted to the right a specified number of bits.</p>
2205
2206<h5>Arguments:</h5>
2207<p>The first argument to the '<tt>ashr</tt>' instruction must be an
2208<a href="#t_integer">integer</a> type. The second argument must be an
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2209'<tt>i8</tt>' type.</p>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2210
2211<h5>Semantics:</h5>
2212<p>This instruction always performs an arithmetic shift right operation,
2213regardless of whether the arguments are signed or not. The <tt>var2</tt> most
2214significant bits will be filled with the sign bit of <tt>var1</tt>.</p>
2215
2216<h5>Example:</h5>
2217<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2218 &lt;result&gt; = ashr i32 4, i8 1 <i>; yields {i32}:result = 2</i>
2219 &lt;result&gt; = ashr i32 4, i8 2 <i>; yields {i32}:result = 1</i>
2220 &lt;result&gt; = ashr i8 4, i8 3 <i>; yields {i8}:result = 0</i>
2221 &lt;result&gt; = ashr i8 -2, i8 1 <i>; yields {i8 }:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2222</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2223</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2224
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2225<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2226<div class="doc_subsection">
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2227 <a name="vectorops">Vector Operations</a>
2228</div>
2229
2230<div class="doc_text">
2231
2232<p>LLVM supports several instructions to represent vector operations in a
2233target-independent manner. This instructions cover the element-access and
2234vector-specific operations needed to process vectors effectively. While LLVM
2235does directly support these vector operations, many sophisticated algorithms
2236will want to use target-specific intrinsics to take full advantage of a specific
2237target.</p>
2238
2239</div>
2240
2241<!-- _______________________________________________________________________ -->
2242<div class="doc_subsubsection">
2243 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2244</div>
2245
2246<div class="doc_text">
2247
2248<h5>Syntax:</h5>
2249
2250<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2251 &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]2252</pre>
2253
2254<h5>Overview:</h5>
2255
2256<p>
2257The '<tt>extractelement</tt>' instruction extracts a single scalar
2258element from a packed vector at a specified index.
2259</p>
2260
2261
2262<h5>Arguments:</h5>
2263
2264<p>
2265The first operand of an '<tt>extractelement</tt>' instruction is a
2266value of <a href="#t_packed">packed</a> type. The second operand is
2267an index indicating the position from which to extract the element.
2268The index may be a variable.</p>
2269
2270<h5>Semantics:</h5>
2271
2272<p>
2273The result is a scalar of the same type as the element type of
2274<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2275<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2276results are undefined.
2277</p>
2278
2279<h5>Example:</h5>
2280
2281<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2282 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2283</pre>
2284</div>
2285
2286
2287<!-- _______________________________________________________________________ -->
2288<div class="doc_subsubsection">
2289 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2290</div>
2291
2292<div class="doc_text">
2293
2294<h5>Syntax:</h5>
2295
2296<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2297 &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]2298</pre>
2299
2300<h5>Overview:</h5>
2301
2302<p>
2303The '<tt>insertelement</tt>' instruction inserts a scalar
2304element into a packed vector at a specified index.
2305</p>
2306
2307
2308<h5>Arguments:</h5>
2309
2310<p>
2311The first operand of an '<tt>insertelement</tt>' instruction is a
2312value of <a href="#t_packed">packed</a> type. The second operand is a
2313scalar value whose type must equal the element type of the first
2314operand. The third operand is an index indicating the position at
2315which to insert the value. The index may be a variable.</p>
2316
2317<h5>Semantics:</h5>
2318
2319<p>
2320The result is a packed vector of the same type as <tt>val</tt>. Its
2321element values are those of <tt>val</tt> except at position
2322<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2323exceeds the length of <tt>val</tt>, the results are undefined.
2324</p>
2325
2326<h5>Example:</h5>
2327
2328<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2329 %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]2330</pre>
2331</div>
2332
2333<!-- _______________________________________________________________________ -->
2334<div class="doc_subsubsection">
2335 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2336</div>
2337
2338<div class="doc_text">
2339
2340<h5>Syntax:</h5>
2341
2342<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2343 &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]2344</pre>
2345
2346<h5>Overview:</h5>
2347
2348<p>
2349The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2350from two input vectors, returning a vector of the same type.
2351</p>
2352
2353<h5>Arguments:</h5>
2354
2355<p>
2356The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2357with types that match each other and types that match the result of the
2358instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2359of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2360</p>
2361
2362<p>
2363The shuffle mask operand is required to be a constant vector with either
2364constant integer or undef values.
2365</p>
2366
2367<h5>Semantics:</h5>
2368
2369<p>
2370The elements of the two input vectors are numbered from left to right across
2371both of the vectors. The shuffle mask operand specifies, for each element of
2372the result vector, which element of the two input registers the result element
2373gets. The element selector may be undef (meaning "don't care") and the second
2374operand may be undef if performing a shuffle from only one vector.
2375</p>
2376
2377<h5>Example:</h5>
2378
2379<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2380 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2381 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2382 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2383 &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]2384</pre>
2385</div>
2386
Tanya Lattner09474292006-04-14 19:24:33 +0000[diff] [blame]2387
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2388<!-- ======================================================================= -->
2389<div class="doc_subsection">
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2390 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2391</div>
2392
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2393<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2394
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2395<p>A key design point of an SSA-based representation is how it
2396represents memory. In LLVM, no memory locations are in SSA form, which
2397makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2398allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2399
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2400</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2401
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2402<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2403<div class="doc_subsubsection">
2404 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2405</div>
2406
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2407<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2408
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2409<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2410
2411<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2412 &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]2413</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2414
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2415<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2416
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2417<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2418heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2419
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2420<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2421
2422<p>The '<tt>malloc</tt>' instruction allocates
2423<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]2424bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2425appropriate type to the program. If "NumElements" is specified, it is the
2426number of elements allocated. If an alignment is specified, the value result
2427of the allocation is guaranteed to be aligned to at least that boundary. If
2428not specified, or if zero, the target can choose to align the allocation on any
2429convenient boundary.</p>
2430
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2431<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2432
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2433<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2434
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2435<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2436a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2437
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2438<h5>Example:</h5>
2439
2440<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2441 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2442
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2443 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2444 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2445 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2446 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2447 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2448</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2449</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2450
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2451<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2452<div class="doc_subsubsection">
2453 <a name="i_free">'<tt>free</tt>' Instruction</a>
2454</div>
2455
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2456<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2457
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2458<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2459
2460<pre>
2461 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2462</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2463
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2464<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2465
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2466<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2467memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2468
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2469<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2470
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2471<p>'<tt>value</tt>' shall be a pointer value that points to a value
2472that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2473instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2474
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2475<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2476
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2477<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2478after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2479
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2480<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2481
2482<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2483 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2484 free [4 x i8]* %array
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2485</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2486</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2487
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2488<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2489<div class="doc_subsubsection">
2490 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2491</div>
2492
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2493<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2494
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2495<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2496
2497<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2498 &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]2499</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2500
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2501<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2502
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2503<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2504stack frame of the procedure that is live until the current function
2505returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2506
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2507<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2508
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2509<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2510bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2511appropriate type to the program. If "NumElements" is specified, it is the
2512number of elements allocated. If an alignment is specified, the value result
2513of the allocation is guaranteed to be aligned to at least that boundary. If
2514not specified, or if zero, the target can choose to align the allocation on any
2515convenient boundary.</p>
2516
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2517<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2518
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2519<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2520
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2521<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2522memory is automatically released when the function returns. The '<tt>alloca</tt>'
2523instruction is commonly used to represent automatic variables that must
2524have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]2525 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]2526instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2527
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2528<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2529
2530<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2531 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2532 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2533 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2534 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2535</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2536</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2537
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2538<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2539<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2540Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2541<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2542<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2543<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]2544<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2545<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2546<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2547<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2548address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2549 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2550marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2551the number or order of execution of this <tt>load</tt> with other
2552volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2553instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2554<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2555<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2556<h5>Examples:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2557<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2558 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2559 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2560 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2561</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2562</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2563<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2564<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2565Instruction</a> </div>
Reid Spencer035ab572006-11-09 21:18:01 +0000[diff] [blame]2566<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2567<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2568<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]2569 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]2570</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2571<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2572<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2573<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2574<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2575to 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]2576operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2577operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2578optimizer is not allowed to modify the number or order of execution of
2579this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2580 href="#i_store">store</a></tt> instructions.</p>
2581<h5>Semantics:</h5>
2582<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2583at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2584<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2585<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2586 <a
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2587 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2588 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2589</pre>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2590</div>
2591
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2592<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2593<div class="doc_subsubsection">
2594 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2595</div>
2596
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2597<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2598<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2599<pre>
2600 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2601</pre>
2602
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2603<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2604
2605<p>
2606The '<tt>getelementptr</tt>' instruction is used to get the address of a
2607subelement of an aggregate data structure.</p>
2608
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2609<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2610
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2611<p>This instruction takes a list of integer operands that indicate what
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2612elements of the aggregate object to index to. The actual types of the arguments
2613provided depend on the type of the first pointer argument. The
2614'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2615levels 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]2616structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2617into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2618be sign extended to 64-bit values.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2619
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2620<p>For example, let's consider a C code fragment and how it gets
2621compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2622
2623<pre>
2624 struct RT {
2625 char A;
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2626 i32 B[10][20];
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2627 char C;
2628 };
2629 struct ST {
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2630 i32 X;
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2631 double Y;
2632 struct RT Z;
2633 };
2634
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2635 define i32 *foo(struct ST *s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2636 return &amp;s[1].Z.B[5][13];
2637 }
2638</pre>
2639
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2640<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2641
2642<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2643 %RT = type { i8 , [10 x [20 x i32]], i8 }
2644 %ST = type { i32, double, %RT }
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2645
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2646 implementation
2647
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2648 define i32* %foo(%ST* %s) {
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2649 entry:
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2650 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2651 ret i32* %reg
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2652 }
2653</pre>
2654
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2655<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2656
2657<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2658on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencer85f5b5b2006-12-04 21:29:24 +0000[diff] [blame]2659and <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]2660<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]2661to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencer42ddd842006-12-03 16:53:48 +0000[diff] [blame]2662<b>constants</b>.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2663
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2664<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]2665type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2666}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2667the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2668i8 }</tt>' type, another structure. The third index indexes into the second
2669element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2670array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2671'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2672to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2673
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2674<p>Note that it is perfectly legal to index partially through a
2675structure, returning a pointer to an inner element. Because of this,
2676the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2677
2678<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2679 define i32* %foo(%ST* %s) {
2680 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2681 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2682 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2683 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2684 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2685 ret i32* %t5
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2686 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2687</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2688
2689<p>Note that it is undefined to access an array out of bounds: array and
2690pointer indexes must always be within the defined bounds of the array type.
2691The one exception for this rules is zero length arrays. These arrays are
2692defined to be accessible as variable length arrays, which requires access
2693beyond the zero'th element.</p>
2694
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2695<p>The getelementptr instruction is often confusing. For some more insight
2696into how it works, see <a href="GetElementPtr.html">the getelementptr
2697FAQ</a>.</p>
2698
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2699<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2700
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2701<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2702 <i>; yields [12 x i8]*:aptr</i>
2703 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2704</pre>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2705</div>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2706
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2707<!-- ======================================================================= -->
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2708<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2709</div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2710<div class="doc_text">
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2711<p>The instructions in this category are the conversion instructions (casting)
2712which all take a single operand and a type. They perform various bit conversions
2713on the operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2714</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2715
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2716<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2717<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2718 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2719</div>
2720<div class="doc_text">
2721
2722<h5>Syntax:</h5>
2723<pre>
2724 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2725</pre>
2726
2727<h5>Overview:</h5>
2728<p>
2729The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2730</p>
2731
2732<h5>Arguments:</h5>
2733<p>
2734The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2735be 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]2736and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2737type. The bit size of <tt>value</tt> must be larger than the bit size of
2738<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2739
2740<h5>Semantics:</h5>
2741<p>
2742The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2743and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2744larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2745It will always truncate bits.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2746
2747<h5>Example:</h5>
2748<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2749 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2750 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2751 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2752</pre>
2753</div>
2754
2755<!-- _______________________________________________________________________ -->
2756<div class="doc_subsubsection">
2757 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2758</div>
2759<div class="doc_text">
2760
2761<h5>Syntax:</h5>
2762<pre>
2763 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2764</pre>
2765
2766<h5>Overview:</h5>
2767<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2768<tt>ty2</tt>.</p>
2769
2770
2771<h5>Arguments:</h5>
2772<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]2773<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2774also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2775<tt>value</tt> must be smaller than the bit size of the destination type,
2776<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2777
2778<h5>Semantics:</h5>
2779<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2780bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2781the operand and the type are the same size, no bit filling is done and the
2782cast is considered a <i>no-op cast</i> because no bits change (only the type
2783changes).</p>
2784
Reid Spencerb5929522007-01-12 15:46:11 +0000[diff] [blame]2785<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]2786
2787<h5>Example:</h5>
2788<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2789 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2790 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2791</pre>
2792</div>
2793
2794<!-- _______________________________________________________________________ -->
2795<div class="doc_subsubsection">
2796 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2797</div>
2798<div class="doc_text">
2799
2800<h5>Syntax:</h5>
2801<pre>
2802 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2803</pre>
2804
2805<h5>Overview:</h5>
2806<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2807
2808<h5>Arguments:</h5>
2809<p>
2810The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]2811<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2812also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2813<tt>value</tt> must be smaller than the bit size of the destination type,
2814<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2815
2816<h5>Semantics:</h5>
2817<p>
2818The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2819bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2820the type <tt>ty2</tt>. When the the operand and the type are the same size,
2821no bit filling is done and the cast is considered a <i>no-op cast</i> because
2822no bits change (only the type changes).</p>
2823
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2824<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]2825
2826<h5>Example:</h5>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2827<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2828 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2829 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2830</pre>
2831</div>
2832
2833<!-- _______________________________________________________________________ -->
2834<div class="doc_subsubsection">
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2835 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2836</div>
2837
2838<div class="doc_text">
2839
2840<h5>Syntax:</h5>
2841
2842<pre>
2843 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2844</pre>
2845
2846<h5>Overview:</h5>
2847<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2848<tt>ty2</tt>.</p>
2849
2850
2851<h5>Arguments:</h5>
2852<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2853 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2854cast it to. The size of <tt>value</tt> must be larger than the size of
2855<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2856<i>no-op cast</i>.</p>
2857
2858<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2859<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2860<a href="#t_floating">floating point</a> type to a smaller
2861<a href="#t_floating">floating point</a> type. If the value cannot fit within
2862the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2863
2864<h5>Example:</h5>
2865<pre>
2866 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2867 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2868</pre>
2869</div>
2870
2871<!-- _______________________________________________________________________ -->
2872<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2873 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2874</div>
2875<div class="doc_text">
2876
2877<h5>Syntax:</h5>
2878<pre>
2879 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2880</pre>
2881
2882<h5>Overview:</h5>
2883<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2884floating point value.</p>
2885
2886<h5>Arguments:</h5>
2887<p>The '<tt>fpext</tt>' instruction takes a
2888<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2889and a <a href="#t_floating">floating point</a> type to cast it to. The source
2890type must be smaller than the destination type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2891
2892<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2893<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
2894<a href="t_floating">floating point</a> type to a larger
2895<a href="t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
2896used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]2897<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]2898
2899<h5>Example:</h5>
2900<pre>
2901 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2902 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2903</pre>
2904</div>
2905
2906<!-- _______________________________________________________________________ -->
2907<div class="doc_subsubsection">
Reid Spencer24d6da52007-01-21 00:29:26 +0000[diff] [blame]2908 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2909</div>
2910<div class="doc_text">
2911
2912<h5>Syntax:</h5>
2913<pre>
2914 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2915</pre>
2916
2917<h5>Overview:</h5>
2918<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2919unsigned integer equivalent of type <tt>ty2</tt>.
2920</p>
2921
2922<h5>Arguments:</h5>
2923<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2924<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]2925must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2926
2927<h5>Semantics:</h5>
2928<p> The '<tt>fp2uint</tt>' instruction converts its
2929<a href="#t_floating">floating point</a> operand into the nearest (rounding
2930towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2931the results are undefined.</p>
2932
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2933<p>When converting to i1, the conversion is done as a comparison against
2934zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2935If 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]2936
2937<h5>Example:</h5>
2938<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2939 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
2940 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2941 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2942</pre>
2943</div>
2944
2945<!-- _______________________________________________________________________ -->
2946<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2947 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2948</div>
2949<div class="doc_text">
2950
2951<h5>Syntax:</h5>
2952<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2953 &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]2954</pre>
2955
2956<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2957<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2958<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]2959</p>
2960
2961
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2962<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2963<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]2964<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]2965must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2966
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2967<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2968<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2969<a href="#t_floating">floating point</a> operand into the nearest (rounding
2970towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
2971the results are undefined.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2972
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2973<p>When converting to i1, the conversion is done as a comparison against
2974zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2975If 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]2976
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2977<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2978<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]2979 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
2980 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]2981 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2982</pre>
2983</div>
2984
2985<!-- _______________________________________________________________________ -->
2986<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2987 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2988</div>
2989<div class="doc_text">
2990
2991<h5>Syntax:</h5>
2992<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2993 &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]2994</pre>
2995
2996<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2997<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2998integer and converts that value to the <tt>ty2</tt> type.</p>
2999
3000
3001<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3002<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]3003<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]3004be a <a href="#t_floating">floating point</a> type.</p>
3005
3006<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3007<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3008integer quantity and converts it to the corresponding floating point value. If
3009the value cannot fit in the floating point value, the results are undefined.</p>
3010
3011
3012<h5>Example:</h5>
3013<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3014 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3015 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3016</pre>
3017</div>
3018
3019<!-- _______________________________________________________________________ -->
3020<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3021 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3022</div>
3023<div class="doc_text">
3024
3025<h5>Syntax:</h5>
3026<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3027 &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]3028</pre>
3029
3030<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3031<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3032integer and converts that value to the <tt>ty2</tt> type.</p>
3033
3034<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3035<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]3036<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]3037a <a href="#t_floating">floating point</a> type.</p>
3038
3039<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]3040<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3041integer quantity and converts it to the corresponding floating point value. If
3042the value cannot fit in the floating point value, the results are undefined.</p>
3043
3044<h5>Example:</h5>
3045<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3046 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3047 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3048</pre>
3049</div>
3050
3051<!-- _______________________________________________________________________ -->
3052<div class="doc_subsubsection">
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3053 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3054</div>
3055<div class="doc_text">
3056
3057<h5>Syntax:</h5>
3058<pre>
3059 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3060</pre>
3061
3062<h5>Overview:</h5>
3063<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3064the integer type <tt>ty2</tt>.</p>
3065
3066<h5>Arguments:</h5>
3067<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3068must be a <a href="t_pointer">pointer</a> value, and a type to cast it to
3069<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3070
3071<h5>Semantics:</h5>
3072<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3073<tt>ty2</tt> by interpreting the pointer value as an integer and either
3074truncating or zero extending that value to the size of the integer type. If
3075<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3076<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3077are the same size, then nothing is done (<i>no-op cast</i>).</p>
3078
3079<h5>Example:</h5>
3080<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3081 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3082 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3083</pre>
3084</div>
3085
3086<!-- _______________________________________________________________________ -->
3087<div class="doc_subsubsection">
3088 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3089</div>
3090<div class="doc_text">
3091
3092<h5>Syntax:</h5>
3093<pre>
3094 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3095</pre>
3096
3097<h5>Overview:</h5>
3098<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3099a pointer type, <tt>ty2</tt>.</p>
3100
3101<h5>Arguments:</h5>
3102<p>The '<tt>inttoptr</tt>' instruction takes an <a href="i_integer">integer</a>
3103value to cast, and a type to cast it to, which must be a
Anton Korobeynikov7f705592007-01-12 19:20:47 +0000[diff] [blame]3104<a href="#t_pointer">pointer</a> type.
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3105
3106<h5>Semantics:</h5>
3107<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3108<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3109the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3110size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3111the size of a pointer then a zero extension is done. If they are the same size,
3112nothing is done (<i>no-op cast</i>).</p>
3113
3114<h5>Example:</h5>
3115<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3116 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3117 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3118 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3119</pre>
3120</div>
3121
3122<!-- _______________________________________________________________________ -->
3123<div class="doc_subsubsection">
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3124 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3125</div>
3126<div class="doc_text">
3127
3128<h5>Syntax:</h5>
3129<pre>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3130 &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]3131</pre>
3132
3133<h5>Overview:</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 Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3135<tt>ty2</tt> without changing any bits.</p>
3136
3137<h5>Arguments:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3138<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3139a first class value, and a type to cast it to, which must also be a <a
3140 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencer19b569f2007-01-09 20:08:58 +0000[diff] [blame]3141and the destination type, <tt>ty2</tt>, must be identical. If the source
3142type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3143
3144<h5>Semantics:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3145<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3146<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3147this conversion. The conversion is done as if the <tt>value</tt> had been
3148stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3149converted to other pointer types with this instruction. To convert pointers to
3150other types, use the <a href="#i_inttoptr">inttoptr</a> or
3151<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3152
3153<h5>Example:</h5>
3154<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3155 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3156 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3157 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]3158</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3159</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3160
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3161<!-- ======================================================================= -->
3162<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3163<div class="doc_text">
3164<p>The instructions in this category are the "miscellaneous"
3165instructions, which defy better classification.</p>
3166</div>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3167
3168<!-- _______________________________________________________________________ -->
3169<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3170</div>
3171<div class="doc_text">
3172<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3173<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3174<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3175</pre>
3176<h5>Overview:</h5>
3177<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3178of its two integer operands.</p>
3179<h5>Arguments:</h5>
3180<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3181the condition code which indicates the kind of comparison to perform. It is not
3182a value, just a keyword. The possibilities for the condition code are:
3183<ol>
3184 <li><tt>eq</tt>: equal</li>
3185 <li><tt>ne</tt>: not equal </li>
3186 <li><tt>ugt</tt>: unsigned greater than</li>
3187 <li><tt>uge</tt>: unsigned greater or equal</li>
3188 <li><tt>ult</tt>: unsigned less than</li>
3189 <li><tt>ule</tt>: unsigned less or equal</li>
3190 <li><tt>sgt</tt>: signed greater than</li>
3191 <li><tt>sge</tt>: signed greater or equal</li>
3192 <li><tt>slt</tt>: signed less than</li>
3193 <li><tt>sle</tt>: signed less or equal</li>
3194</ol>
Chris Lattner3b19d652007-01-15 01:54:13 +0000[diff] [blame]3195<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3196<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3197<h5>Semantics:</h5>
3198<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3199the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3200yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3201<ol>
3202 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3203 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3204 </li>
3205 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3206 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3207 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3208 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3209 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3210 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3211 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3212 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3213 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3214 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3215 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3216 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3217 <li><tt>sge</tt>: interprets the operands as signed values and yields
3218 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3219 <li><tt>slt</tt>: interprets the operands as signed values and yields
3220 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3221 <li><tt>sle</tt>: interprets the operands as signed values and yields
3222 <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]3223</ol>
3224<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3225values are treated as integers and then compared.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3226
3227<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3228<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3229 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3230 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3231 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3232 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3233 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3234</pre>
3235</div>
3236
3237<!-- _______________________________________________________________________ -->
3238<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3239</div>
3240<div class="doc_text">
3241<h5>Syntax:</h5>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3242<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3243<i>; yields {i1}:result</i>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3244</pre>
3245<h5>Overview:</h5>
3246<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3247of its floating point operands.</p>
3248<h5>Arguments:</h5>
3249<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3250the condition code which indicates the kind of comparison to perform. It is not
3251a value, just a keyword. The possibilities for the condition code are:
3252<ol>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3253 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3254 <li><tt>oeq</tt>: ordered and equal</li>
3255 <li><tt>ogt</tt>: ordered and greater than </li>
3256 <li><tt>oge</tt>: ordered and greater than or equal</li>
3257 <li><tt>olt</tt>: ordered and less than </li>
3258 <li><tt>ole</tt>: ordered and less than or equal</li>
3259 <li><tt>one</tt>: ordered and not equal</li>
3260 <li><tt>ord</tt>: ordered (no nans)</li>
3261 <li><tt>ueq</tt>: unordered or equal</li>
3262 <li><tt>ugt</tt>: unordered or greater than </li>
3263 <li><tt>uge</tt>: unordered or greater than or equal</li>
3264 <li><tt>ult</tt>: unordered or less than </li>
3265 <li><tt>ule</tt>: unordered or less than or equal</li>
3266 <li><tt>une</tt>: unordered or not equal</li>
3267 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3268 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3269</ol>
Reid Spencer93a49852006-12-06 07:08:07 +0000[diff] [blame]3270<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3271<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer350f8aa2007-01-04 05:19:58 +0000[diff] [blame]3272<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3273<a href="#t_floating">floating point</a> typed. They must have identical
3274types.</p>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3275<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3276<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3277<h5>Semantics:</h5>
3278<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3279the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3280yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3281<ol>
3282 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3283 <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]3284 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3285 <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]3286 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3287 <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]3288 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3289 <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]3290 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3291 <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]3292 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3293 <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]3294 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3295 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3296 <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]3297 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3298 <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]3299 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3300 <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]3301 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3302 <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]3303 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3304 <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]3305 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3306 <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]3307 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3308 <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]3309 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3310</ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3311
3312<h5>Example:</h5>
3313<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3314 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3315 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3316 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3317</pre>
3318</div>
3319
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3320<!-- _______________________________________________________________________ -->
3321<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3322Instruction</a> </div>
3323<div class="doc_text">
3324<h5>Syntax:</h5>
3325<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3326<h5>Overview:</h5>
3327<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3328the SSA graph representing the function.</p>
3329<h5>Arguments:</h5>
3330<p>The type of the incoming values are specified with the first type
3331field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3332as arguments, with one pair for each predecessor basic block of the
3333current block. Only values of <a href="#t_firstclass">first class</a>
3334type may be used as the value arguments to the PHI node. Only labels
3335may be used as the label arguments.</p>
3336<p>There must be no non-phi instructions between the start of a basic
3337block and the PHI instructions: i.e. PHI instructions must be first in
3338a basic block.</p>
3339<h5>Semantics:</h5>
3340<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3341value specified by the parameter, depending on which basic block we
3342came from in the last <a href="#terminators">terminator</a> instruction.</p>
3343<h5>Example:</h5>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3344<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]3345</div>
3346
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3347<!-- _______________________________________________________________________ -->
3348<div class="doc_subsubsection">
3349 <a name="i_select">'<tt>select</tt>' Instruction</a>
3350</div>
3351
3352<div class="doc_text">
3353
3354<h5>Syntax:</h5>
3355
3356<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3357 &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]3358</pre>
3359
3360<h5>Overview:</h5>
3361
3362<p>
3363The '<tt>select</tt>' instruction is used to choose one value based on a
3364condition, without branching.
3365</p>
3366
3367
3368<h5>Arguments:</h5>
3369
3370<p>
3371The '<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.
3372</p>
3373
3374<h5>Semantics:</h5>
3375
3376<p>
3377If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3378value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3379</p>
3380
3381<h5>Example:</h5>
3382
3383<pre>
Reid Spencerc78f3372007-01-12 03:35:51 +0000[diff] [blame]3384 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3385</pre>
3386</div>
3387
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]3388
3389<!-- _______________________________________________________________________ -->
3390<div class="doc_subsubsection">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3391 <a name="i_call">'<tt>call</tt>' Instruction</a>
3392</div>
3393
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3394<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3395
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3396<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3397<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3398 &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]3399</pre>
3400
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3401<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3402
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3403<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3404
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3405<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3406
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3407<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3408
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3409<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3410 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3411 <p>The optional "tail" marker indicates whether the callee function accesses
3412 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3413 function call is eligible for tail call optimization. Note that calls may
3414 be marked "tail" even if they do not occur before a <a
3415 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3416 </li>
3417 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3418 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
3419 convention</a> the call should use. If none is specified, the call defaults
3420 to using C calling conventions.
3421 </li>
3422 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3423 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3424 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3425 signature. This type can be omitted if the function is not varargs and
3426 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3427 </li>
3428 <li>
3429 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3430 be invoked. In most cases, this is a direct function invocation, but
3431 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3432 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3433 </li>
3434 <li>
3435 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]3436 function signature argument types. All arguments must be of
3437 <a href="#t_firstclass">first class</a> type. If the function signature
3438 indicates the function accepts a variable number of arguments, the extra
3439 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3440 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3441</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3442
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3443<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3444
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3445<p>The '<tt>call</tt>' instruction is used to cause control flow to
3446transfer to a specified function, with its incoming arguments bound to
3447the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3448instruction in the called function, control flow continues with the
3449instruction after the function call, and the return value of the
3450function is bound to the result argument. This is a simpler case of
3451the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3452
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3453<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3454
3455<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3456 %retval = call i32 %test(i32 %argc)
3457 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3458 %X = tail call i32 %foo()
3459 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3460</pre>
3461
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3462</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3463
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3464<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3465<div class="doc_subsubsection">
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3466 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3467</div>
3468
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3469<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3470
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3471<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3472
3473<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3474 &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]3475</pre>
3476
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3477<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3478
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3479<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3480the "variable argument" area of a function call. It is used to implement the
3481<tt>va_arg</tt> macro in C.</p>
3482
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3483<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3484
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3485<p>This instruction takes a <tt>va_list*</tt> value and the type of
3486the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3487increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3488actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3489
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3490<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3491
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3492<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3493type from the specified <tt>va_list</tt> and causes the
3494<tt>va_list</tt> to point to the next argument. For more information,
3495see the variable argument handling <a href="#int_varargs">Intrinsic
3496Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3497
3498<p>It is legal for this instruction to be called in a function which does not
3499take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3500function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3501
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3502<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3503href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3504argument.</p>
3505
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3506<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3507
3508<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3509
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3510</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3511
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3512<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3513<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3514<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3515
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3516<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3517
3518<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3519well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3520restrictions. Overall, these instructions represent an extension mechanism for
3521the LLVM language that does not require changing all of the transformations in
3522LLVM to add to the language (or the bytecode reader/writer, the parser,
3523etc...).</p>
3524
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3525<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3526prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3527this. Intrinsic functions must always be external functions: you cannot define
3528the body of intrinsic functions. Intrinsic functions may only be used in call
3529or invoke instructions: it is illegal to take the address of an intrinsic
3530function. Additionally, because intrinsic functions are part of the LLVM
3531language, it is required that they all be documented here if any are added.</p>
3532
3533
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3534<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]3535href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3536</p>
3537
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3538</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3539
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3540<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3541<div class="doc_subsection">
3542 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3543</div>
3544
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3545<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3546
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3547<p>Variable argument support is defined in LLVM with the <a
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3548 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3549intrinsic functions. These functions are related to the similarly
3550named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3551
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3552<p>All of these functions operate on arguments that use a
3553target-specific value type "<tt>va_list</tt>". The LLVM assembly
3554language reference manual does not define what this type is, so all
3555transformations should be prepared to handle intrinsics with any type
3556used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3557
Chris Lattner374ab302006-05-15 17:26:46 +0000[diff] [blame]3558<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]3559instruction and the variable argument handling intrinsic functions are
3560used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3561
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3562<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3563define i32 %test(i32 %X, ...) {
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3564 ; Initialize variable argument processing
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3565 %ap = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3566 %ap2 = bitcast i8** %ap to i8*
3567 call void %<a href="#i_va_start">llvm.va_start</a>(i8* %ap2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3568
3569 ; Read a single integer argument
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3570 %tmp = va_arg i8 ** %ap, i32
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3571
3572 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3573 %aq = alloca i8 *
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3574 %aq2 = bitcast i8** %aq to i8*
3575 call void %<a href="#i_va_copy">llvm.va_copy</a>(i8 *%aq2, i8* %ap2)
3576 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %aq2)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3577
3578 ; Stop processing of arguments.
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3579 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %ap2)
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3580 ret i32 %tmp
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3581}
3582</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3583</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3584
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3585<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3586<div class="doc_subsubsection">
3587 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3588</div>
3589
3590
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3591<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3592<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3593<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3594<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3595<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3596<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3597href="#i_va_arg">va_arg</a></tt>.</p>
3598
3599<h5>Arguments:</h5>
3600
3601<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3602
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3603<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3604
3605<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3606macro available in C. In a target-dependent way, it initializes the
3607<tt>va_list</tt> element the argument points to, so that the next call to
3608<tt>va_arg</tt> will produce the first variable argument passed to the function.
3609Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3610last argument of the function, the compiler can figure that out.</p>
3611
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3612</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3613
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3614<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3615<div class="doc_subsubsection">
3616 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3617</div>
3618
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3619<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3620<h5>Syntax:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3621<pre> declare void %llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3622<h5>Overview:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3623
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3624<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
3625which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
3626or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3627
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3628<h5>Arguments:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3629
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3630<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3631
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3632<h5>Semantics:</h5>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3633
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3634<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]3635macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
3636Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
3637 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
3638with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3639
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3640</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3641
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3642<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3643<div class="doc_subsubsection">
3644 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3645</div>
3646
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3647<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3648
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3649<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3650
3651<pre>
Chris Lattnerb75137d2007-01-08 07:55:15 +0000[diff] [blame]3652 declare void %llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3653</pre>
3654
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3655<h5>Overview:</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 copies the current argument position from
3658the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3659
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3660<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3661
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3662<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]3663The 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]3664
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3665
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3666<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3667
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3668<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3669available in C. In a target-dependent way, it copies the source
3670<tt>va_list</tt> element into the destination list. This intrinsic is necessary
3671because 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]3672arbitrarily complex and require memory allocation, for example.</p>
3673
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3674</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3675
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3676<!-- ======================================================================= -->
3677<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3678 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3679</div>
3680
3681<div class="doc_text">
3682
3683<p>
3684LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3685Collection</a> requires the implementation and generation of these intrinsics.
3686These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
3687stack</a>, as well as garbage collector implementations that require <a
3688href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
3689Front-ends for type-safe garbage collected languages should generate these
3690intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3691href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3692</p>
3693</div>
3694
3695<!-- _______________________________________________________________________ -->
3696<div class="doc_subsubsection">
3697 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3698</div>
3699
3700<div class="doc_text">
3701
3702<h5>Syntax:</h5>
3703
3704<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3705 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3706</pre>
3707
3708<h5>Overview:</h5>
3709
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]3710<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]3711the code generator, and allows some metadata to be associated with it.</p>
3712
3713<h5>Arguments:</h5>
3714
3715<p>The first argument specifies the address of a stack object that contains the
3716root pointer. The second pointer (which must be either a constant or a global
3717value address) contains the meta-data to be associated with the root.</p>
3718
3719<h5>Semantics:</h5>
3720
3721<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3722location. At compile-time, the code generator generates information to allow
3723the runtime to find the pointer at GC safe points.
3724</p>
3725
3726</div>
3727
3728
3729<!-- _______________________________________________________________________ -->
3730<div class="doc_subsubsection">
3731 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
3732</div>
3733
3734<div class="doc_text">
3735
3736<h5>Syntax:</h5>
3737
3738<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3739 declare i8 * %llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3740</pre>
3741
3742<h5>Overview:</h5>
3743
3744<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3745locations, allowing garbage collector implementations that require read
3746barriers.</p>
3747
3748<h5>Arguments:</h5>
3749
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3750<p>The second argument is the address to read from, which should be an address
3751allocated from the garbage collector. The first object is a pointer to the
3752start of the referenced object, if needed by the language runtime (otherwise
3753null).</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3754
3755<h5>Semantics:</h5>
3756
3757<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3758instruction, but may be replaced with substantially more complex code by the
3759garbage collector runtime, as needed.</p>
3760
3761</div>
3762
3763
3764<!-- _______________________________________________________________________ -->
3765<div class="doc_subsubsection">
3766 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
3767</div>
3768
3769<div class="doc_text">
3770
3771<h5>Syntax:</h5>
3772
3773<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3774 declare void %llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3775</pre>
3776
3777<h5>Overview:</h5>
3778
3779<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3780locations, allowing garbage collector implementations that require write
3781barriers (such as generational or reference counting collectors).</p>
3782
3783<h5>Arguments:</h5>
3784
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3785<p>The first argument is the reference to store, the second is the start of the
3786object to store it to, and the third is the address of the field of Obj to
3787store to. If the runtime does not require a pointer to the object, Obj may be
3788null.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3789
3790<h5>Semantics:</h5>
3791
3792<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3793instruction, but may be replaced with substantially more complex code by the
3794garbage collector runtime, as needed.</p>
3795
3796</div>
3797
3798
3799
3800<!-- ======================================================================= -->
3801<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3802 <a name="int_codegen">Code Generator Intrinsics</a>
3803</div>
3804
3805<div class="doc_text">
3806<p>
3807These intrinsics are provided by LLVM to expose special features that may only
3808be implemented with code generator support.
3809</p>
3810
3811</div>
3812
3813<!-- _______________________________________________________________________ -->
3814<div class="doc_subsubsection">
3815 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
3816</div>
3817
3818<div class="doc_text">
3819
3820<h5>Syntax:</h5>
3821<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3822 declare i8 *%llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3823</pre>
3824
3825<h5>Overview:</h5>
3826
3827<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3828The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3829target-specific value indicating the return address of the current function
3830or one of its callers.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3831</p>
3832
3833<h5>Arguments:</h5>
3834
3835<p>
3836The argument to this intrinsic indicates which function to return the address
3837for. Zero indicates the calling function, one indicates its caller, etc. The
3838argument is <b>required</b> to be a constant integer value.
3839</p>
3840
3841<h5>Semantics:</h5>
3842
3843<p>
3844The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3845the return address of the specified call frame, or zero if it cannot be
3846identified. The value returned by this intrinsic is likely to be incorrect or 0
3847for arguments other than zero, so it should only be used for debugging purposes.
3848</p>
3849
3850<p>
3851Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3852aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3853source-language caller.
3854</p>
3855</div>
3856
3857
3858<!-- _______________________________________________________________________ -->
3859<div class="doc_subsubsection">
3860 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
3861</div>
3862
3863<div class="doc_text">
3864
3865<h5>Syntax:</h5>
3866<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3867 declare i8 *%llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3868</pre>
3869
3870<h5>Overview:</h5>
3871
3872<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3873The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3874target-specific frame pointer value for the specified stack frame.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3875</p>
3876
3877<h5>Arguments:</h5>
3878
3879<p>
3880The argument to this intrinsic indicates which function to return the frame
3881pointer for. Zero indicates the calling function, one indicates its caller,
3882etc. The argument is <b>required</b> to be a constant integer value.
3883</p>
3884
3885<h5>Semantics:</h5>
3886
3887<p>
3888The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3889the frame address of the specified call frame, or zero if it cannot be
3890identified. The value returned by this intrinsic is likely to be incorrect or 0
3891for arguments other than zero, so it should only be used for debugging purposes.
3892</p>
3893
3894<p>
3895Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3896aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3897source-language caller.
3898</p>
3899</div>
3900
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3901<!-- _______________________________________________________________________ -->
3902<div class="doc_subsubsection">
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3903 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
3904</div>
3905
3906<div class="doc_text">
3907
3908<h5>Syntax:</h5>
3909<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3910 declare i8 *%llvm.stacksave()
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3911</pre>
3912
3913<h5>Overview:</h5>
3914
3915<p>
3916The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
3917the function stack, for use with <a href="#i_stackrestore">
3918<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3919features like scoped automatic variable sized arrays in C99.
3920</p>
3921
3922<h5>Semantics:</h5>
3923
3924<p>
3925This intrinsic returns a opaque pointer value that can be passed to <a
3926href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
3927<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
3928<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
3929state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
3930practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
3931that were allocated after the <tt>llvm.stacksave</tt> was executed.
3932</p>
3933
3934</div>
3935
3936<!-- _______________________________________________________________________ -->
3937<div class="doc_subsubsection">
3938 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
3939</div>
3940
3941<div class="doc_text">
3942
3943<h5>Syntax:</h5>
3944<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3945 declare void %llvm.stackrestore(i8 * %ptr)
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3946</pre>
3947
3948<h5>Overview:</h5>
3949
3950<p>
3951The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
3952the function stack to the state it was in when the corresponding <a
3953href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
3954useful for implementing language features like scoped automatic variable sized
3955arrays in C99.
3956</p>
3957
3958<h5>Semantics:</h5>
3959
3960<p>
3961See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
3962</p>
3963
3964</div>
3965
3966
3967<!-- _______________________________________________________________________ -->
3968<div class="doc_subsubsection">
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3969 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
3970</div>
3971
3972<div class="doc_text">
3973
3974<h5>Syntax:</h5>
3975<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]3976 declare void %llvm.prefetch(i8 * &lt;address&gt;,
3977 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3978</pre>
3979
3980<h5>Overview:</h5>
3981
3982
3983<p>
3984The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3985a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
3986no
3987effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]3988characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3989</p>
3990
3991<h5>Arguments:</h5>
3992
3993<p>
3994<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
3995determining if the fetch should be for a read (0) or write (1), and
3996<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]3997locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3998<tt>locality</tt> arguments must be constant integers.
3999</p>
4000
4001<h5>Semantics:</h5>
4002
4003<p>
4004This intrinsic does not modify the behavior of the program. In particular,
4005prefetches cannot trap and do not produce a value. On targets that support this
4006intrinsic, the prefetch can provide hints to the processor cache for better
4007performance.
4008</p>
4009
4010</div>
4011
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4012<!-- _______________________________________________________________________ -->
4013<div class="doc_subsubsection">
4014 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4015</div>
4016
4017<div class="doc_text">
4018
4019<h5>Syntax:</h5>
4020<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4021 declare void %llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4022</pre>
4023
4024<h5>Overview:</h5>
4025
4026
4027<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4028The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4029(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4030code to simulators and other tools. The method is target specific, but it is
4031expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]4032The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnerd07c3f42005-11-15 06:07:55 +0000[diff] [blame]4033after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb3e7afd2006-03-24 07:16:10 +0000[diff] [blame]4034optimizations. The intended use is to be inserted after optimizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]4035correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]4036</p>
4037
4038<h5>Arguments:</h5>
4039
4040<p>
4041<tt>id</tt> is a numerical id identifying the marker.
4042</p>
4043
4044<h5>Semantics:</h5>
4045
4046<p>
4047This intrinsic does not modify the behavior of the program. Backends that do not
4048support this intrinisic may ignore it.
4049</p>
4050
4051</div>
4052
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4053<!-- _______________________________________________________________________ -->
4054<div class="doc_subsubsection">
4055 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4056</div>
4057
4058<div class="doc_text">
4059
4060<h5>Syntax:</h5>
4061<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4062 declare i64 %llvm.readcyclecounter( )
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]4063</pre>
4064
4065<h5>Overview:</h5>
4066
4067
4068<p>
4069The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4070counter register (or similar low latency, high accuracy clocks) on those targets
4071that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4072As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4073should only be used for small timings.
4074</p>
4075
4076<h5>Semantics:</h5>
4077
4078<p>
4079When directly supported, reading the cycle counter should not modify any memory.
4080Implementations are allowed to either return a application specific value or a
4081system wide value. On backends without support, this is lowered to a constant 0.
4082</p>
4083
4084</div>
4085
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4086<!-- ======================================================================= -->
4087<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4088 <a name="int_libc">Standard C Library Intrinsics</a>
4089</div>
4090
4091<div class="doc_text">
4092<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4093LLVM provides intrinsics for a few important standard C library functions.
4094These intrinsics allow source-language front-ends to pass information about the
4095alignment of the pointer arguments to the code generator, providing opportunity
4096for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4097</p>
4098
4099</div>
4100
4101<!-- _______________________________________________________________________ -->
4102<div class="doc_subsubsection">
4103 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4104</div>
4105
4106<div class="doc_text">
4107
4108<h5>Syntax:</h5>
4109<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4110 declare void %llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4111 i32 &lt;len&gt;, i32 &lt;align&gt;)
4112 declare void %llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4113 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4114</pre>
4115
4116<h5>Overview:</h5>
4117
4118<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4119The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4120location to the destination location.
4121</p>
4122
4123<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4124Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4125intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4126</p>
4127
4128<h5>Arguments:</h5>
4129
4130<p>
4131The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4132the source. The third argument is an integer argument
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4133specifying the number of bytes to copy, and the fourth argument is the alignment
4134of the source and destination locations.
4135</p>
4136
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4137<p>
4138If 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]4139the caller guarantees that both the source and destination pointers are aligned
4140to that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4141</p>
4142
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4143<h5>Semantics:</h5>
4144
4145<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4146The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4147location to the destination location, which are not allowed to overlap. It
4148copies "len" bytes of memory over. If the argument is known to be aligned to
4149some boundary, this can be specified as the fourth argument, otherwise it should
4150be set to 0 or 1.
4151</p>
4152</div>
4153
4154
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4155<!-- _______________________________________________________________________ -->
4156<div class="doc_subsubsection">
4157 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4158</div>
4159
4160<div class="doc_text">
4161
4162<h5>Syntax:</h5>
4163<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4164 declare void %llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4165 i32 &lt;len&gt;, i32 &lt;align&gt;)
4166 declare void %llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4167 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4168</pre>
4169
4170<h5>Overview:</h5>
4171
4172<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4173The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4174location to the destination location. It is similar to the
4175'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4176</p>
4177
4178<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4179Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4180intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4181</p>
4182
4183<h5>Arguments:</h5>
4184
4185<p>
4186The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4187the source. The third argument is an integer argument
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4188specifying the number of bytes to copy, and the fourth argument is the alignment
4189of the source and destination locations.
4190</p>
4191
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4192<p>
4193If 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]4194the caller guarantees that the source and destination pointers are aligned to
4195that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4196</p>
4197
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4198<h5>Semantics:</h5>
4199
4200<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4201The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4202location to the destination location, which may overlap. It
4203copies "len" bytes of memory over. If the argument is known to be aligned to
4204some boundary, this can be specified as the fourth argument, otherwise it should
4205be set to 0 or 1.
4206</p>
4207</div>
4208
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4209
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4210<!-- _______________________________________________________________________ -->
4211<div class="doc_subsubsection">
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4212 <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4213</div>
4214
4215<div class="doc_text">
4216
4217<h5>Syntax:</h5>
4218<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4219 declare void %llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4220 i32 &lt;len&gt;, i32 &lt;align&gt;)
4221 declare void %llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4222 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4223</pre>
4224
4225<h5>Overview:</h5>
4226
4227<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4228The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4229byte value.
4230</p>
4231
4232<p>
4233Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4234does not return a value, and takes an extra alignment argument.
4235</p>
4236
4237<h5>Arguments:</h5>
4238
4239<p>
4240The first argument is a pointer to the destination to fill, the second is the
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4241byte value to fill it with, the third argument is an integer
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4242argument specifying the number of bytes to fill, and the fourth argument is the
4243known alignment of destination location.
4244</p>
4245
4246<p>
4247If 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]4248the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4249</p>
4250
4251<h5>Semantics:</h5>
4252
4253<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4254The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4255the
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4256destination location. If the argument is known to be aligned to some boundary,
4257this can be specified as the fourth argument, otherwise it should be set to 0 or
42581.
4259</p>
4260</div>
4261
4262
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4263<!-- _______________________________________________________________________ -->
4264<div class="doc_subsubsection">
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4265 <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4266</div>
4267
4268<div class="doc_text">
4269
4270<h5>Syntax:</h5>
4271<pre>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4272 declare float %llvm.sqrt.f32(float %Val)
4273 declare double %llvm.sqrt.f64(double %Val)
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4274</pre>
4275
4276<h5>Overview:</h5>
4277
4278<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4279The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4280returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4281<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4282negative numbers (which allows for better optimization).
4283</p>
4284
4285<h5>Arguments:</h5>
4286
4287<p>
4288The argument and return value are floating point numbers of the same type.
4289</p>
4290
4291<h5>Semantics:</h5>
4292
4293<p>
4294This function returns the sqrt of the specified operand if it is a positive
4295floating point number.
4296</p>
4297</div>
4298
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4299<!-- _______________________________________________________________________ -->
4300<div class="doc_subsubsection">
4301 <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4302</div>
4303
4304<div class="doc_text">
4305
4306<h5>Syntax:</h5>
4307<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4308 declare float %llvm.powi.f32(float %Val, i32 %power)
4309 declare double %llvm.powi.f64(double %Val, i32 %power)
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4310</pre>
4311
4312<h5>Overview:</h5>
4313
4314<p>
4315The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4316specified (positive or negative) power. The order of evaluation of
4317multiplications is not defined.
4318</p>
4319
4320<h5>Arguments:</h5>
4321
4322<p>
4323The second argument is an integer power, and the first is a value to raise to
4324that power.
4325</p>
4326
4327<h5>Semantics:</h5>
4328
4329<p>
4330This function returns the first value raised to the second power with an
4331unspecified sequence of rounding operations.</p>
4332</div>
4333
4334
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4335<!-- ======================================================================= -->
4336<div class="doc_subsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4337 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4338</div>
4339
4340<div class="doc_text">
4341<p>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4342LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4343These allow efficient code generation for some algorithms.
4344</p>
4345
4346</div>
4347
4348<!-- _______________________________________________________________________ -->
4349<div class="doc_subsubsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4350 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4351</div>
4352
4353<div class="doc_text">
4354
4355<h5>Syntax:</h5>
4356<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4357 declare i16 %llvm.bswap.i16(i16 &lt;id&gt;)
4358 declare i32 %llvm.bswap.i32(i32 &lt;id&gt;)
4359 declare i64 %llvm.bswap.i64(i64 &lt;id&gt;)
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4360</pre>
4361
4362<h5>Overview:</h5>
4363
4364<p>
4365The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
436664 bit quantity. These are useful for performing operations on data that is not
4367in the target's native byte order.
4368</p>
4369
4370<h5>Semantics:</h5>
4371
4372<p>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4373The <tt>llvm.bswap.16</tt> intrinsic returns an i16 value that has the high
4374and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4375intrinsic returns an i32 value that has the four bytes of the input i32
4376swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
4377i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt>
4378intrinsic extends this concept to 64 bits.
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4379</p>
4380
4381</div>
4382
4383<!-- _______________________________________________________________________ -->
4384<div class="doc_subsubsection">
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4385 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4386</div>
4387
4388<div class="doc_text">
4389
4390<h5>Syntax:</h5>
4391<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4392 declare i8 %llvm.ctpop.i8 (i8 &lt;src&gt;)
4393 declare i16 %llvm.ctpop.i16(i16 &lt;src&gt;)
4394 declare i32 %llvm.ctpop.i32(i32 &lt;src&gt;)
4395 declare i64 %llvm.ctpop.i64(i64 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4396</pre>
4397
4398<h5>Overview:</h5>
4399
4400<p>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4401The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4402value.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4403</p>
4404
4405<h5>Arguments:</h5>
4406
4407<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4408The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4409integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4410</p>
4411
4412<h5>Semantics:</h5>
4413
4414<p>
4415The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4416</p>
4417</div>
4418
4419<!-- _______________________________________________________________________ -->
4420<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4421 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4422</div>
4423
4424<div class="doc_text">
4425
4426<h5>Syntax:</h5>
4427<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4428 declare i8 %llvm.ctlz.i8 (i8 &lt;src&gt;)
4429 declare i16 %llvm.ctlz.i16(i16 &lt;src&gt;)
4430 declare i32 %llvm.ctlz.i32(i32 &lt;src&gt;)
4431 declare i64 %llvm.ctlz.i64(i64 &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4432</pre>
4433
4434<h5>Overview:</h5>
4435
4436<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4437The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4438leading zeros in a variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4439</p>
4440
4441<h5>Arguments:</h5>
4442
4443<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4444The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4445integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4446</p>
4447
4448<h5>Semantics:</h5>
4449
4450<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4451The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4452in 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]4453of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4454</p>
4455</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4456
4457
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4458
4459<!-- _______________________________________________________________________ -->
4460<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4461 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4462</div>
4463
4464<div class="doc_text">
4465
4466<h5>Syntax:</h5>
4467<pre>
Reid Spencerca86e162006-12-31 07:07:53 +0000[diff] [blame]4468 declare i8 %llvm.cttz.i8 (i8 &lt;src&gt;)
4469 declare i16 %llvm.cttz.i16(i16 &lt;src&gt;)
4470 declare i32 %llvm.cttz.i32(i32 &lt;src&gt;)
4471 declare i64 %llvm.cttz.i64(i64 &lt;src&gt;)
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4472</pre>
4473
4474<h5>Overview:</h5>
4475
4476<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4477The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4478trailing zeros.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4479</p>
4480
4481<h5>Arguments:</h5>
4482
4483<p>
4484The only argument is the value to be counted. The argument may be of any
Reid Spencera5173382007-01-04 16:43:23 +0000[diff] [blame]4485integer type. The return type must match the argument type.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4486</p>
4487
4488<h5>Semantics:</h5>
4489
4490<p>
4491The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4492in a variable. If the src == 0 then the result is the size in bits of the type
4493of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4494</p>
4495</div>
4496
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4497<!-- ======================================================================= -->
4498<div class="doc_subsection">
4499 <a name="int_debugger">Debugger Intrinsics</a>
4500</div>
4501
4502<div class="doc_text">
4503<p>
4504The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4505are described in the <a
4506href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4507Debugging</a> document.
4508</p>
4509</div>
4510
4511
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4512<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4513<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4514<address>
4515 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4516 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
4517 <a href="http://validator.w3.org/check/referer"><img
4518 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4519
4520 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]4521 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4522 Last modified: $Date$
4523</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]4524</body>
4525</html>