Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / e558c682510156b4f87c278354166d8acc7bc49c / . / docs / LangRef.html
blob: 5b7b1256efbb0e69b273095227cbd0c818b11193 [file] [log] [blame]
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3<html>
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>
27 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]28 </ol>
29 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]30 <li><a href="#typesystem">Type System</a>
31 <ol>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]32 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]33 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]34 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]35 </ol>
36 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]37 <li><a href="#t_derived">Derived Types</a>
38 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]39 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]40 <li><a href="#t_function">Function Type</a></li>
41 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]42 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]43 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]44 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]45 </ol>
46 </li>
47 </ol>
48 </li>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]49 <li><a href="#constants">Constants</a>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]50 <ol>
51 <li><a href="#simpleconstants">Simple Constants</a>
52 <li><a href="#aggregateconstants">Aggregate Constants</a>
53 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
54 <li><a href="#undefvalues">Undefined Values</a>
55 <li><a href="#constantexprs">Constant Expressions</a>
56 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]57 </li>
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]58 <li><a href="#othervalues">Other Values</a>
59 <ol>
60 <li><a href="#inlineasm">Inline Assembler Expressions</a>
61 </ol>
62 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]63 <li><a href="#instref">Instruction Reference</a>
64 <ol>
65 <li><a href="#terminators">Terminator Instructions</a>
66 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]67 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
68 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]69 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
70 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]71 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]72 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]73 </ol>
74 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]75 <li><a href="#binaryops">Binary Operations</a>
76 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]77 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
78 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
79 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]80 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
81 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
82 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]83 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
84 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
85 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]86 </ol>
87 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]88 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
89 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]90 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]91 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]92 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
93 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]94 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
95 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]96 </ol>
97 </li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]98 <li><a href="#vectorops">Vector Operations</a>
99 <ol>
100 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
101 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
102 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]103 </ol>
104 </li>
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]105 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]106 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]107 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
108 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
109 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]110 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
111 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
112 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]113 </ol>
114 </li>
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]115 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]116 <ol>
117 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
118 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
119 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
120 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
121 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]122 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
123 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
124 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
125 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]126 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
127 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]128 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]129 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]130 <li><a href="#otherops">Other Operations</a>
131 <ol>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]132 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
133 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]134 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]135 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]136 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]137 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]138 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]139 </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 Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]142 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]143 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]144 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
145 <ol>
146 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
147 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
148 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
149 </ol>
150 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]151 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
152 <ol>
153 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
154 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
155 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
156 </ol>
157 </li>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]158 <li><a href="#int_codegen">Code Generator Intrinsics</a>
159 <ol>
160 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
161 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]162 <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
163 <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]164 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]165 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]166 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswell7123e272004-04-09 16:43:20 +0000[diff] [blame]167 </ol>
168 </li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]169 <li><a href="#int_libc">Standard C Library Intrinsics</a>
170 <ol>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]171 <li><a href="#i_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
172 <li><a href="#i_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
173 <li><a href="#i_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]174 <li><a href="#i_isunordered">'<tt>llvm.isunordered.*</tt>' Intrinsic</a></li>
175 <li><a href="#i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]176 <li><a href="#i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]177 </ol>
178 </li>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]179 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]180 <ol>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]181 <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]182 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
183 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
184 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]185 </ol>
186 </li>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]187 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]188 </ol>
189 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]190</ol>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]191
192<div class="doc_author">
193 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
194 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]195</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]196
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]197<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]198<div class="doc_section"> <a name="abstract">Abstract </a></div>
199<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]200
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]201<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]202<p>This document is a reference manual for the LLVM assembly language.
203LLVM is an SSA based representation that provides type safety,
204low-level operations, flexibility, and the capability of representing
205'all' high-level languages cleanly. It is the common code
206representation used throughout all phases of the LLVM compilation
207strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]208</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]209
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]210<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]211<div class="doc_section"> <a name="introduction">Introduction</a> </div>
212<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]213
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]214<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]215
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]216<p>The LLVM code representation is designed to be used in three
217different forms: as an in-memory compiler IR, as an on-disk bytecode
218representation (suitable for fast loading by a Just-In-Time compiler),
219and as a human readable assembly language representation. This allows
220LLVM to provide a powerful intermediate representation for efficient
221compiler transformations and analysis, while providing a natural means
222to debug and visualize the transformations. The three different forms
223of LLVM are all equivalent. This document describes the human readable
224representation and notation.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]225
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]226<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]227while being expressive, typed, and extensible at the same time. It
228aims to be a "universal IR" of sorts, by being at a low enough level
229that high-level ideas may be cleanly mapped to it (similar to how
230microprocessors are "universal IR's", allowing many source languages to
231be mapped to them). By providing type information, LLVM can be used as
232the target of optimizations: for example, through pointer analysis, it
233can be proven that a C automatic variable is never accessed outside of
234the current function... allowing it to be promoted to a simple SSA
235value instead of a memory location.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]236
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]237</div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]238
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]239<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]240<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]241
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]242<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]243
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]244<p>It is important to note that this document describes 'well formed'
245LLVM assembly language. There is a difference between what the parser
246accepts and what is considered 'well formed'. For example, the
247following instruction is syntactically okay, but not well formed:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]248
249<pre>
250 %x = <a href="#i_add">add</a> int 1, %x
251</pre>
252
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]253<p>...because the definition of <tt>%x</tt> does not dominate all of
254its uses. The LLVM infrastructure provides a verification pass that may
255be used to verify that an LLVM module is well formed. This pass is
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]256automatically run by the parser after parsing input assembly and by
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]257the optimizer before it outputs bytecode. The violations pointed out
258by the verifier pass indicate bugs in transformation passes or input to
259the parser.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]260
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]261<!-- Describe the typesetting conventions here. --> </div>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]262
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]263<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]264<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]265<!-- *********************************************************************** -->
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]266
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]267<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]268
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]269<p>LLVM uses three different forms of identifiers, for different
270purposes:</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]271
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]272<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]273 <li>Named values are represented as a string of characters with a '%' prefix.
274 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
275 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
276 Identifiers which require other characters in their names can be surrounded
277 with quotes. In this way, anything except a <tt>"</tt> character can be used
278 in a name.</li>
279
280 <li>Unnamed values are represented as an unsigned numeric value with a '%'
281 prefix. For example, %12, %2, %44.</li>
282
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]283 <li>Constants, which are described in a <a href="#constants">section about
284 constants</a>, below.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]285</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]286
287<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
288don't need to worry about name clashes with reserved words, and the set of
289reserved words may be expanded in the future without penalty. Additionally,
290unnamed identifiers allow a compiler to quickly come up with a temporary
291variable without having to avoid symbol table conflicts.</p>
292
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]293<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]294languages. There are keywords for different opcodes
295('<tt><a href="#i_add">add</a></tt>',
296 '<tt><a href="#i_bitcast">bitcast</a></tt>',
297 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]298href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
299and others. These reserved words cannot conflict with variable names, because
300none of them start with a '%' character.</p>
301
302<p>Here is an example of LLVM code to multiply the integer variable
303'<tt>%X</tt>' by 8:</p>
304
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]305<p>The easy way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]306
307<pre>
308 %result = <a href="#i_mul">mul</a> uint %X, 8
309</pre>
310
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]311<p>After strength reduction:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]312
313<pre>
314 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
315</pre>
316
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]317<p>And the hard way:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]318
319<pre>
320 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
321 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
322 %result = <a href="#i_add">add</a> uint %1, %1
323</pre>
324
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]325<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
326important lexical features of LLVM:</p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]327
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]328<ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]329
330 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
331 line.</li>
332
333 <li>Unnamed temporaries are created when the result of a computation is not
334 assigned to a named value.</li>
335
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]336 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]337
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]338</ol>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]339
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]340<p>...and it also shows a convention that we follow in this document. When
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]341demonstrating instructions, we will follow an instruction with a comment that
342defines the type and name of value produced. Comments are shown in italic
343text.</p>
344
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]345</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]346
347<!-- *********************************************************************** -->
348<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
349<!-- *********************************************************************** -->
350
351<!-- ======================================================================= -->
352<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
353</div>
354
355<div class="doc_text">
356
357<p>LLVM programs are composed of "Module"s, each of which is a
358translation unit of the input programs. Each module consists of
359functions, global variables, and symbol table entries. Modules may be
360combined together with the LLVM linker, which merges function (and
361global variable) definitions, resolves forward declarations, and merges
362symbol table entries. Here is an example of the "hello world" module:</p>
363
364<pre><i>; Declare the string constant as a global constant...</i>
365<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
366 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
367
368<i>; External declaration of the puts function</i>
369<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
370
Chris Lattner81c01f02006-06-13 03:05:47 +0000[diff] [blame]371<i>; Global variable / Function body section separator</i>
372implementation
373
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]374<i>; Definition of main function</i>
375int %main() { <i>; int()* </i>
376 <i>; Convert [13x sbyte]* to sbyte *...</i>
377 %cast210 = <a
378 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
379
380 <i>; Call puts function to write out the string to stdout...</i>
381 <a
382 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
383 <a
384 href="#i_ret">ret</a> int 0<br>}<br></pre>
385
386<p>This example is made up of a <a href="#globalvars">global variable</a>
387named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
388function, and a <a href="#functionstructure">function definition</a>
389for "<tt>main</tt>".</p>
390
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]391<p>In general, a module is made up of a list of global values,
392where both functions and global variables are global values. Global values are
393represented by a pointer to a memory location (in this case, a pointer to an
394array of char, and a pointer to a function), and have one of the following <a
395href="#linkage">linkage types</a>.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]396
Chris Lattner81c01f02006-06-13 03:05:47 +0000[diff] [blame]397<p>Due to a limitation in the current LLVM assembly parser (it is limited by
398one-token lookahead), modules are split into two pieces by the "implementation"
399keyword. Global variable prototypes and definitions must occur before the
400keyword, and function definitions must occur after it. Function prototypes may
401occur either before or after it. In the future, the implementation keyword may
402become a noop, if the parser gets smarter.</p>
403
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]404</div>
405
406<!-- ======================================================================= -->
407<div class="doc_subsection">
408 <a name="linkage">Linkage Types</a>
409</div>
410
411<div class="doc_text">
412
413<p>
414All Global Variables and Functions have one of the following types of linkage:
415</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]416
417<dl>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]418
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]419 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]420
421 <dd>Global values with internal linkage are only directly accessible by
422 objects in the current module. In particular, linking code into a module with
423 an internal global value may cause the internal to be renamed as necessary to
424 avoid collisions. Because the symbol is internal to the module, all
425 references can be updated. This corresponds to the notion of the
426 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]427 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]428
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]429 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]430
431 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
432 the twist that linking together two modules defining the same
433 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
434 is typically used to implement inline functions. Unreferenced
435 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]436 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]437
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]438 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]439
440 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
441 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
442 used to implement constructs in C such as "<tt>int X;</tt>" at global scope.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]443 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]444
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]445 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]446
447 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
448 pointer to array type. When two global variables with appending linkage are
449 linked together, the two global arrays are appended together. This is the
450 LLVM, typesafe, equivalent of having the system linker append together
451 "sections" with identical names when .o files are linked.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]452 </dd>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]453
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]454 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]455
456 <dd>If none of the above identifiers are used, the global is externally
457 visible, meaning that it participates in linkage and can be used to resolve
458 external symbol references.
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]459 </dd>
Anton Korobeynikovb74ed072006-09-14 18:23:27 +0000[diff] [blame]460
461 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
462
463 <dd>"<tt>extern_weak</tt>" TBD
464 </dd>
465
466 <p>
467 The next two types of linkage are targeted for Microsoft Windows platform
468 only. They are designed to support importing (exporting) symbols from (to)
469 DLLs.
470 </p>
471
472 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
473
474 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
475 or variable via a global pointer to a pointer that is set up by the DLL
476 exporting the symbol. On Microsoft Windows targets, the pointer name is
477 formed by combining <code>_imp__</code> and the function or variable name.
478 </dd>
479
480 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
481
482 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
483 pointer to a pointer in a DLL, so that it can be referenced with the
484 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
485 name is formed by combining <code>_imp__</code> and the function or variable
486 name.
487 </dd>
488
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]489</dl>
490
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]491<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
492variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
493variable and was linked with this one, one of the two would be renamed,
494preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
495external (i.e., lacking any linkage declarations), they are accessible
496outside of the current module. It is illegal for a function <i>declaration</i>
497to have any linkage type other than "externally visible".</a></p>
Chris Lattnere5d947b2004-12-09 16:36:40 +0000[diff] [blame]498
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]499</div>
500
501<!-- ======================================================================= -->
502<div class="doc_subsection">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]503 <a name="callingconv">Calling Conventions</a>
504</div>
505
506<div class="doc_text">
507
508<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
509and <a href="#i_invoke">invokes</a> can all have an optional calling convention
510specified for the call. The calling convention of any pair of dynamic
511caller/callee must match, or the behavior of the program is undefined. The
512following calling conventions are supported by LLVM, and more may be added in
513the future:</p>
514
515<dl>
516 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
517
518 <dd>This calling convention (the default if no other calling convention is
519 specified) matches the target C calling conventions. This calling convention
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]520 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]521 prototype and implemented declaration of the function (as does normal C).
522 </dd>
523
Chris Lattner5710ce92006-05-19 21:15:36 +0000[diff] [blame]524 <dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
525
526 <dd>This calling convention matches the target C calling conventions, except
527 that functions with this convention are required to take a pointer as their
528 first argument, and the return type of the function must be void. This is
529 used for C functions that return aggregates by-value. In this case, the
530 function has been transformed to take a pointer to the struct as the first
531 argument to the function. For targets where the ABI specifies specific
532 behavior for structure-return calls, the calling convention can be used to
533 distinguish between struct return functions and other functions that take a
534 pointer to a struct as the first argument.
535 </dd>
536
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]537 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
538
539 <dd>This calling convention attempts to make calls as fast as possible
540 (e.g. by passing things in registers). This calling convention allows the
541 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattner8cdc5bc2005-05-06 23:08:23 +0000[diff] [blame]542 without having to conform to an externally specified ABI. Implementations of
543 this convention should allow arbitrary tail call optimization to be supported.
544 This calling convention does not support varargs and requires the prototype of
545 all callees to exactly match the prototype of the function definition.
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]546 </dd>
547
548 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
549
550 <dd>This calling convention attempts to make code in the caller as efficient
551 as possible under the assumption that the call is not commonly executed. As
552 such, these calls often preserve all registers so that the call does not break
553 any live ranges in the caller side. This calling convention does not support
554 varargs and requires the prototype of all callees to exactly match the
555 prototype of the function definition.
556 </dd>
557
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]558 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]559
560 <dd>Any calling convention may be specified by number, allowing
561 target-specific calling conventions to be used. Target specific calling
562 conventions start at 64.
563 </dd>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]564</dl>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]565
566<p>More calling conventions can be added/defined on an as-needed basis, to
567support pascal conventions or any other well-known target-independent
568convention.</p>
569
570</div>
571
572<!-- ======================================================================= -->
573<div class="doc_subsection">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]574 <a name="globalvars">Global Variables</a>
575</div>
576
577<div class="doc_text">
578
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]579<p>Global variables define regions of memory allocated at compilation time
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]580instead of run-time. Global variables may optionally be initialized, may have
581an explicit section to be placed in, and may
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]582have an optional explicit alignment specified. A
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]583variable may be defined as a global "constant," which indicates that the
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]584contents of the variable will <b>never</b> be modified (enabling better
585optimization, allowing the global data to be placed in the read-only section of
586an executable, etc). Note that variables that need runtime initialization
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]587cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner3689a342005-02-12 19:30:21 +0000[diff] [blame]588
589<p>
590LLVM explicitly allows <em>declarations</em> of global variables to be marked
591constant, even if the final definition of the global is not. This capability
592can be used to enable slightly better optimization of the program, but requires
593the language definition to guarantee that optimizations based on the
594'constantness' are valid for the translation units that do not include the
595definition.
596</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]597
598<p>As SSA values, global variables define pointer values that are in
599scope (i.e. they dominate) all basic blocks in the program. Global
600variables always define a pointer to their "content" type because they
601describe a region of memory, and all memory objects in LLVM are
602accessed through pointers.</p>
603
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]604<p>LLVM allows an explicit section to be specified for globals. If the target
605supports it, it will emit globals to the section specified.</p>
606
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]607<p>An explicit alignment may be specified for a global. If not present, or if
608the alignment is set to zero, the alignment of the global is set by the target
609to whatever it feels convenient. If an explicit alignment is specified, the
610global is forced to have at least that much alignment. All alignments must be
611a power of 2.</p>
612
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]613</div>
614
615
616<!-- ======================================================================= -->
617<div class="doc_subsection">
618 <a name="functionstructure">Functions</a>
619</div>
620
621<div class="doc_text">
622
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]623<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
624type</a>, an optional <a href="#callingconv">calling convention</a>, a return
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]625type, a function name, a (possibly empty) argument list, an optional section,
626an optional alignment, an opening curly brace,
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]627a list of basic blocks, and a closing curly brace. LLVM function declarations
628are defined with the "<tt>declare</tt>" keyword, an optional <a
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]629href="#callingconv">calling convention</a>, a return type, a function name,
630a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]631
632<p>A function definition contains a list of basic blocks, forming the CFG for
633the function. Each basic block may optionally start with a label (giving the
634basic block a symbol table entry), contains a list of instructions, and ends
635with a <a href="#terminators">terminator</a> instruction (such as a branch or
636function return).</p>
637
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]638<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]639executed on entrance to the function, and it is not allowed to have predecessor
640basic blocks (i.e. there can not be any branches to the entry block of a
641function). Because the block can have no predecessors, it also cannot have any
642<a href="#i_phi">PHI nodes</a>.</p>
643
644<p>LLVM functions are identified by their name and type signature. Hence, two
645functions with the same name but different parameter lists or return values are
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]646considered different functions, and LLVM will resolve references to each
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]647appropriately.</p>
648
Chris Lattner88f6c462005-11-12 00:45:07 +0000[diff] [blame]649<p>LLVM allows an explicit section to be specified for functions. If the target
650supports it, it will emit functions to the section specified.</p>
651
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]652<p>An explicit alignment may be specified for a function. If not present, or if
653the alignment is set to zero, the alignment of the function is set by the target
654to whatever it feels convenient. If an explicit alignment is specified, the
655function is forced to have at least that much alignment. All alignments must be
656a power of 2.</p>
657
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]658</div>
659
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]660<!-- ======================================================================= -->
661<div class="doc_subsection">
Chris Lattner1eeeb0c2006-04-08 04:40:53 +0000[diff] [blame]662 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]663</div>
664
665<div class="doc_text">
666<p>
667Modules may contain "module-level inline asm" blocks, which corresponds to the
668GCC "file scope inline asm" blocks. These blocks are internally concatenated by
669LLVM and treated as a single unit, but may be separated in the .ll file if
670desired. The syntax is very simple:
671</p>
672
673<div class="doc_code"><pre>
Chris Lattner52599e12006-01-24 00:37:20 +0000[diff] [blame]674 module asm "inline asm code goes here"
675 module asm "more can go here"
Chris Lattner4e9aba72006-01-23 23:23:47 +0000[diff] [blame]676</pre></div>
677
678<p>The strings can contain any character by escaping non-printable characters.
679 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
680 for the number.
681</p>
682
683<p>
684 The inline asm code is simply printed to the machine code .s file when
685 assembly code is generated.
686</p>
687</div>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]688
689
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]690<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]691<div class="doc_section"> <a name="typesystem">Type System</a> </div>
692<!-- *********************************************************************** -->
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]693
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]694<div class="doc_text">
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]695
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]696<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]697intermediate representation. Being typed enables a number of
698optimizations to be performed on the IR directly, without having to do
699extra analyses on the side before the transformation. A strong type
700system makes it easier to read the generated code and enables novel
701analyses and transformations that are not feasible to perform on normal
702three address code representations.</p>
Chris Lattnerfa730212004-12-09 16:11:40 +0000[diff] [blame]703
704</div>
705
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]706<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]707<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]708<div class="doc_text">
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]709<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]710system. The current set of primitive types is as follows:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]711
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]712<table class="layout">
713 <tr class="layout">
714 <td class="left">
715 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]716 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]717 <tr><th>Type</th><th>Description</th></tr>
718 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]719 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
720 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
721 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
722 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
723 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]724 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]725 </tbody>
726 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]727 </td>
728 <td class="right">
729 <table>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]730 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]731 <tr><th>Type</th><th>Description</th></tr>
732 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukmancfa87bc2005-04-22 18:02:52 +0000[diff] [blame]733 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
734 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
735 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
736 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
737 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]738 </tbody>
739 </table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]740 </td>
741 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]742</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]743</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]744
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]745<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]746<div class="doc_subsubsection"> <a name="t_classifications">Type
747Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]748<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]749<p>These different primitive types fall into a few useful
750classifications:</p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]751
752<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]753 <tbody>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]754 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]755 <tr>
756 <td><a name="t_signed">signed</a></td>
757 <td><tt>sbyte, short, int, long, float, double</tt></td>
758 </tr>
759 <tr>
760 <td><a name="t_unsigned">unsigned</a></td>
761 <td><tt>ubyte, ushort, uint, ulong</tt></td>
762 </tr>
763 <tr>
764 <td><a name="t_integer">integer</a></td>
765 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
766 </tr>
767 <tr>
768 <td><a name="t_integral">integral</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]769 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
770 </td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]771 </tr>
772 <tr>
773 <td><a name="t_floating">floating point</a></td>
774 <td><tt>float, double</tt></td>
775 </tr>
776 <tr>
777 <td><a name="t_firstclass">first class</a></td>
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]778 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
779 float, double, <a href="#t_pointer">pointer</a>,
780 <a href="#t_packed">packed</a></tt></td>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]781 </tr>
782 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]783</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]784
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]785<p>The <a href="#t_firstclass">first class</a> types are perhaps the
786most important. Values of these types are the only ones which can be
787produced by instructions, passed as arguments, or used as operands to
788instructions. This means that all structures and arrays must be
789manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]790</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]791
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]792<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]793<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]794
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]795<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]796
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]797<p>The real power in LLVM comes from the derived types in the system.
798This is what allows a programmer to represent arrays, functions,
799pointers, and other useful types. Note that these derived types may be
800recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]801
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]802</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]803
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]804<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]805<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]806
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]807<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]808
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]809<h5>Overview:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]810
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]811<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]812sequentially in memory. The array type requires a size (number of
813elements) and an underlying data type.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]814
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]815<h5>Syntax:</h5>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]816
817<pre>
818 [&lt;# elements&gt; x &lt;elementtype&gt;]
819</pre>
820
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]821<p>The number of elements is a constant integer value; elementtype may
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]822be any type with a size.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]823
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]824<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]825<table class="layout">
826 <tr class="layout">
827 <td class="left">
828 <tt>[40 x int ]</tt><br/>
829 <tt>[41 x int ]</tt><br/>
830 <tt>[40 x uint]</tt><br/>
831 </td>
832 <td class="left">
833 Array of 40 integer values.<br/>
834 Array of 41 integer values.<br/>
835 Array of 40 unsigned integer values.<br/>
836 </td>
837 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]838</table>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]839<p>Here are some examples of multidimensional arrays:</p>
840<table class="layout">
841 <tr class="layout">
842 <td class="left">
843 <tt>[3 x [4 x int]]</tt><br/>
844 <tt>[12 x [10 x float]]</tt><br/>
845 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
846 </td>
847 <td class="left">
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]848 3x4 array of integer values.<br/>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]849 12x10 array of single precision floating point values.<br/>
850 2x3x4 array of unsigned integer values.<br/>
851 </td>
852 </tr>
853</table>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]854
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]855<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
856length array. Normally, accesses past the end of an array are undefined in
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]857LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
858As a special case, however, zero length arrays are recognized to be variable
859length. This allows implementation of 'pascal style arrays' with the LLVM
860type "{ int, [0 x float]}", for example.</p>
861
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]862</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]863
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]864<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]865<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]866<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]867<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]868<p>The function type can be thought of as a function signature. It
869consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]870Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]871(which are structures of pointers to functions), for indirect function
872calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame]873<p>
874The return type of a function type cannot be an aggregate type.
875</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]876<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]877<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]878<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]879specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]880which indicates that the function takes a variable number of arguments.
881Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]882 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]883<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]884<table class="layout">
885 <tr class="layout">
886 <td class="left">
887 <tt>int (int)</tt> <br/>
888 <tt>float (int, int *) *</tt><br/>
889 <tt>int (sbyte *, ...)</tt><br/>
890 </td>
891 <td class="left">
892 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
893 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukmanc24b7582004-08-12 20:16:08 +0000[diff] [blame]894 <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]895 returning <tt>float</tt>.<br/>
896 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
897 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
898 the signature for <tt>printf</tt> in LLVM.<br/>
899 </td>
900 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]901</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]902
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]903</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]904<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]905<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]906<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]907<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]908<p>The structure type is used to represent a collection of data members
909together in memory. The packing of the field types is defined to match
910the ABI of the underlying processor. The elements of a structure may
911be any type that has a size.</p>
912<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
913and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
914field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
915instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]916<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]917<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]918<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]919<table class="layout">
920 <tr class="layout">
921 <td class="left">
922 <tt>{ int, int, int }</tt><br/>
923 <tt>{ float, int (int) * }</tt><br/>
924 </td>
925 <td class="left">
926 a triple of three <tt>int</tt> values<br/>
927 A pair, where the first element is a <tt>float</tt> and the second element
928 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
929 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
930 </td>
931 </tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]932</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]933</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]934
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]935<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]936<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]937<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]938<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]939<p>As in many languages, the pointer type represents a pointer or
940reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]941<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]942<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]943<h5>Examples:</h5>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]944<table class="layout">
945 <tr class="layout">
946 <td class="left">
947 <tt>[4x int]*</tt><br/>
948 <tt>int (int *) *</tt><br/>
949 </td>
950 <td class="left">
951 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
952 four <tt>int</tt> values<br/>
953 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattnera977c482005-02-19 02:22:14 +0000[diff] [blame]954 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]955 <tt>int</tt>.<br/>
956 </td>
957 </tr>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]958</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]959</div>
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]960
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]961<!-- _______________________________________________________________________ -->
962<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]963<div class="doc_text">
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]964
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]965<h5>Overview:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]966
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]967<p>A packed type is a simple derived type that represents a vector
968of elements. Packed types are used when multiple primitive data
969are operated in parallel using a single instruction (SIMD).
970A packed type requires a size (number of
Chris Lattnerb8d172f2005-11-10 01:44:22 +0000[diff] [blame]971elements) and an underlying primitive data type. Vectors must have a power
972of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]973considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]974
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]975<h5>Syntax:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]976
977<pre>
978 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
979</pre>
980
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]981<p>The number of elements is a constant integer value; elementtype may
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]982be any integral or floating point type.</p>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]983
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]984<h5>Examples:</h5>
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]985
Reid Spencerd3f876c2004-11-01 08:19:36 +0000[diff] [blame]986<table class="layout">
987 <tr class="layout">
988 <td class="left">
989 <tt>&lt;4 x int&gt;</tt><br/>
990 <tt>&lt;8 x float&gt;</tt><br/>
991 <tt>&lt;2 x uint&gt;</tt><br/>
992 </td>
993 <td class="left">
994 Packed vector of 4 integer values.<br/>
995 Packed vector of 8 floating-point values.<br/>
996 Packed vector of 2 unsigned integer values.<br/>
997 </td>
998 </tr>
999</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1000</div>
1001
Chris Lattner69c11bb2005-04-25 17:34:15 +0000[diff] [blame]1002<!-- _______________________________________________________________________ -->
1003<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1004<div class="doc_text">
1005
1006<h5>Overview:</h5>
1007
1008<p>Opaque types are used to represent unknown types in the system. This
1009corresponds (for example) to the C notion of a foward declared structure type.
1010In LLVM, opaque types can eventually be resolved to any type (not just a
1011structure type).</p>
1012
1013<h5>Syntax:</h5>
1014
1015<pre>
1016 opaque
1017</pre>
1018
1019<h5>Examples:</h5>
1020
1021<table class="layout">
1022 <tr class="layout">
1023 <td class="left">
1024 <tt>opaque</tt>
1025 </td>
1026 <td class="left">
1027 An opaque type.<br/>
1028 </td>
1029 </tr>
1030</table>
1031</div>
1032
1033
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1034<!-- *********************************************************************** -->
1035<div class="doc_section"> <a name="constants">Constants</a> </div>
1036<!-- *********************************************************************** -->
1037
1038<div class="doc_text">
1039
1040<p>LLVM has several different basic types of constants. This section describes
1041them all and their syntax.</p>
1042
1043</div>
1044
1045<!-- ======================================================================= -->
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1046<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1047
1048<div class="doc_text">
1049
1050<dl>
1051 <dt><b>Boolean constants</b></dt>
1052
1053 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1054 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
1055 </dd>
1056
1057 <dt><b>Integer constants</b></dt>
1058
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1059 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1060 href="#t_integer">integer</a> type. Negative numbers may be used with signed
1061 integer types.
1062 </dd>
1063
1064 <dt><b>Floating point constants</b></dt>
1065
1066 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1067 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1068 notation (see below). Floating point constants must have a <a
1069 href="#t_floating">floating point</a> type. </dd>
1070
1071 <dt><b>Null pointer constants</b></dt>
1072
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1073 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1074 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1075
1076</dl>
1077
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1078<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1079of floating point constants. For example, the form '<tt>double
10800x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
10814.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencercc16dc32004-12-09 18:02:53 +0000[diff] [blame]1082(and the only time that they are generated by the disassembler) is when a
1083floating point constant must be emitted but it cannot be represented as a
1084decimal floating point number. For example, NaN's, infinities, and other
1085special values are represented in their IEEE hexadecimal format so that
1086assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1087
1088</div>
1089
1090<!-- ======================================================================= -->
1091<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1092</div>
1093
1094<div class="doc_text">
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1095<p>Aggregate constants arise from aggregation of simple constants
1096and smaller aggregate constants.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1097
1098<dl>
1099 <dt><b>Structure constants</b></dt>
1100
1101 <dd>Structure constants are represented with notation similar to structure
1102 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]1103 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
1104 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
1105 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1106 types of elements must match those specified by the type.
1107 </dd>
1108
1109 <dt><b>Array constants</b></dt>
1110
1111 <dd>Array constants are represented with notation similar to array type
1112 definitions (a comma separated list of elements, surrounded by square brackets
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1113 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1114 constants must have <a href="#t_array">array type</a>, and the number and
1115 types of elements must match those specified by the type.
1116 </dd>
1117
1118 <dt><b>Packed constants</b></dt>
1119
1120 <dd>Packed constants are represented with notation similar to packed type
1121 definitions (a comma separated list of elements, surrounded by
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1122 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; int 42,
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1123 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
1124 href="#t_packed">packed type</a>, and the number and types of elements must
1125 match those specified by the type.
1126 </dd>
1127
1128 <dt><b>Zero initialization</b></dt>
1129
1130 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1131 value to zero of <em>any</em> type, including scalar and aggregate types.
1132 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]1133 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1134 initializers.
1135 </dd>
1136</dl>
1137
1138</div>
1139
1140<!-- ======================================================================= -->
1141<div class="doc_subsection">
1142 <a name="globalconstants">Global Variable and Function Addresses</a>
1143</div>
1144
1145<div class="doc_text">
1146
1147<p>The addresses of <a href="#globalvars">global variables</a> and <a
1148href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1149constants. These constants are explicitly referenced when the <a
1150href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1151href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1152file:</p>
1153
1154<pre>
1155 %X = global int 17
1156 %Y = global int 42
1157 %Z = global [2 x int*] [ int* %X, int* %Y ]
1158</pre>
1159
1160</div>
1161
1162<!-- ======================================================================= -->
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1163<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1164<div class="doc_text">
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1165 <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]1166 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1167 a constant is permitted.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1168
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1169 <p>Undefined values indicate to the compiler that the program is well defined
1170 no matter what value is used, giving the compiler more freedom to optimize.
1171 </p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1172</div>
1173
1174<!-- ======================================================================= -->
1175<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1176</div>
1177
1178<div class="doc_text">
1179
1180<p>Constant expressions are used to allow expressions involving other constants
1181to be used as constants. Constant expressions may be of any <a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1182href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1183that does not have side effects (e.g. load and call are not supported). The
1184following is the syntax for constant expressions:</p>
1185
1186<dl>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1187 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1188 <dd>Truncate a constant to another type. The bit size of CST must be larger
1189 than the bit size of TYPE. Both types must be integral.</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1190
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1191 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1192 <dd>Zero extend a constant to another type. The bit size of CST must be
1193 smaller or equal to the bit size of TYPE. Both types must be integral.</dd>
1194
1195 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1196 <dd>Sign extend a constant to another type. The bit size of CST must be
1197 smaller or equal to the bit size of TYPE. Both types must be integral.</dd>
1198
1199 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1200 <dd>Truncate a floating point constant to another floating point type. The
1201 size of CST must be larger than the size of TYPE. Both types must be
1202 floating point.</dd>
1203
1204 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1205 <dd>Floating point extend a constant to another type. The size of CST must be
1206 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1207
1208 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1209 <dd>Convert a floating point constant to the corresponding unsigned integer
1210 constant. TYPE must be an integer type. CST must be floating point. If the
1211 value won't fit in the integer type, the results are undefined.</dd>
1212
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1213 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1214 <dd>Convert a floating point constant to the corresponding signed integer
1215 constant. TYPE must be an integer type. CST must be floating point. If the
1216 value won't fit in the integer type, the results are undefined.</dd>
1217
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1218 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1219 <dd>Convert an unsigned integer constant to the corresponding floating point
1220 constant. TYPE must be floating point. CST must be of integer type. If the
1221 value won't fit in the floating point type, the results are undefined.</dd>
1222
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]1223 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1224 <dd>Convert a signed integer constant to the corresponding floating point
1225 constant. TYPE must be floating point. CST must be of integer type. If the
1226 value won't fit in the floating point type, the results are undefined.</dd>
1227
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]1228 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1229 <dd>Convert a pointer typed constant to the corresponding integer constant
1230 TYPE must be an integer type. CST must be of pointer type. The CST value is
1231 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1232
1233 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1234 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1235 pointer type. CST must be of integer type. The CST value is zero extended,
1236 truncated, or unchanged to make it fit in a pointer size. This one is
1237 <i>really</i> dangerous!</dd>
1238
1239 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1240 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1241 identical (same number of bits). The conversion is done as if the CST value
1242 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]1243 with this operator, just the type. This can be used for conversion of
1244 packed types to any other type, as long as they have the same bit width. For
1245 pointers it is only valid to cast to another pointer type.
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1246 </dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1247
1248 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1249
1250 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1251 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1252 instruction, the index list may have zero or more indexes, which are required
1253 to make sense for the type of "CSTPTR".</dd>
1254
Robert Bocchino9fbe1452006-01-10 19:31:34 +0000[diff] [blame]1255 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1256
1257 <dd>Perform the <a href="#i_select">select operation</a> on
1258 constants.
1259
1260 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1261
1262 <dd>Perform the <a href="#i_extractelement">extractelement
1263 operation</a> on constants.
1264
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]1265 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1266
1267 <dd>Perform the <a href="#i_insertelement">insertelement
1268 operation</a> on constants.
1269
Chris Lattnerc1989542006-04-08 00:13:41 +0000[diff] [blame]1270
1271 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1272
1273 <dd>Perform the <a href="#i_shufflevector">shufflevector
1274 operation</a> on constants.
1275
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1276 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1277
Reid Spencer2dc45b82004-12-09 18:13:12 +0000[diff] [blame]1278 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1279 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1280 binary</a> operations. The constraints on operands are the same as those for
1281 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1282 values are allowed).</dd>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1283</dl>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1284</div>
Chris Lattner9ee5d222004-03-08 16:49:10 +0000[diff] [blame]1285
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1286<!-- *********************************************************************** -->
Chris Lattnere87d6532006-01-25 23:47:57 +0000[diff] [blame]1287<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1288<!-- *********************************************************************** -->
1289
1290<!-- ======================================================================= -->
1291<div class="doc_subsection">
1292<a name="inlineasm">Inline Assembler Expressions</a>
1293</div>
1294
1295<div class="doc_text">
1296
1297<p>
1298LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1299Module-Level Inline Assembly</a>) through the use of a special value. This
1300value represents the inline assembler as a string (containing the instructions
1301to emit), a list of operand constraints (stored as a string), and a flag that
1302indicates whether or not the inline asm expression has side effects. An example
1303inline assembler expression is:
1304</p>
1305
1306<pre>
1307 int(int) asm "bswap $0", "=r,r"
1308</pre>
1309
1310<p>
1311Inline assembler expressions may <b>only</b> be used as the callee operand of
1312a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1313</p>
1314
1315<pre>
1316 %X = call int asm "<a href="#i_bswap">bswap</a> $0", "=r,r"(int %Y)
1317</pre>
1318
1319<p>
1320Inline asms with side effects not visible in the constraint list must be marked
1321as having side effects. This is done through the use of the
1322'<tt>sideeffect</tt>' keyword, like so:
1323</p>
1324
1325<pre>
1326 call void asm sideeffect "eieio", ""()
1327</pre>
1328
1329<p>TODO: The format of the asm and constraints string still need to be
1330documented here. Constraints on what can be done (e.g. duplication, moving, etc
1331need to be documented).
1332</p>
1333
1334</div>
1335
1336<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1337<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1338<!-- *********************************************************************** -->
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1339
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1340<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1341
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1342<p>The LLVM instruction set consists of several different
1343classifications of instructions: <a href="#terminators">terminator
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1344instructions</a>, <a href="#binaryops">binary instructions</a>,
1345<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1346 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1347instructions</a>.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1348
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1349</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1350
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1351<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1352<div class="doc_subsection"> <a name="terminators">Terminator
1353Instructions</a> </div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1354
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1355<div class="doc_text">
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1356
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1357<p>As mentioned <a href="#functionstructure">previously</a>, every
1358basic block in a program ends with a "Terminator" instruction, which
1359indicates which block should be executed after the current block is
1360finished. These terminator instructions typically yield a '<tt>void</tt>'
1361value: they produce control flow, not values (the one exception being
1362the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1363<p>There are six different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1364 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1365instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1366the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1367 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1368 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1369
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1370</div>
Chris Lattnerc3f59762004-12-09 17:30:23 +0000[diff] [blame]1371
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1372<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1373<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1374Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1375<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1376<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1377<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]1378 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1379</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1380<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1381<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1382value) from a function back to the caller.</p>
John Criswell4457dc92004-04-09 16:48:45 +0000[diff] [blame]1383<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1384returns a value and then causes control flow, and one that just causes
1385control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1386<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1387<p>The '<tt>ret</tt>' instruction may return any '<a
1388 href="#t_firstclass">first class</a>' type. Notice that a function is
1389not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1390instruction inside of the function that returns a value that does not
1391match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1392<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1393<p>When the '<tt>ret</tt>' instruction is executed, control flow
1394returns back to the calling function's context. If the caller is a "<a
John Criswellfa081872004-06-25 15:16:57 +0000[diff] [blame]1395 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1396the instruction after the call. If the caller was an "<a
1397 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1398at the beginning of the "normal" destination block. If the instruction
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1399returns a value, that value shall set the call or invoke instruction's
1400return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1401<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1402<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1403 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1404</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1405</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1406<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1407<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1408<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1409<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1410<pre> br bool &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1411</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1412<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1413<p>The '<tt>br</tt>' instruction is used to cause control flow to
1414transfer to a different basic block in the current function. There are
1415two forms of this instruction, corresponding to a conditional branch
1416and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1417<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1418<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1419single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1420unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1421value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1422<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1423<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1424argument is evaluated. If the value is <tt>true</tt>, control flows
1425to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1426control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1427<h5>Example:</h5>
Reid Spencer36d68e42006-11-18 21:55:45 +0000[diff] [blame]1428<pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq, int %a, %b<br> br bool %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1429 href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1430</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1431<!-- _______________________________________________________________________ -->
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1432<div class="doc_subsubsection">
1433 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1434</div>
1435
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1436<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1437<h5>Syntax:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1438
1439<pre>
1440 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1441</pre>
1442
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1443<h5>Overview:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1444
1445<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1446several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1447instruction, allowing a branch to occur to one of many possible
1448destinations.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1449
1450
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1451<h5>Arguments:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1452
1453<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1454comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1455an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1456table is not allowed to contain duplicate constant entries.</p>
1457
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1458<h5>Semantics:</h5>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1459
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1460<p>The <tt>switch</tt> instruction specifies a table of values and
1461destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1462table is searched for the given value. If the value is found, control flow is
1463transfered to the corresponding destination; otherwise, control flow is
1464transfered to the default destination.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1465
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1466<h5>Implementation:</h5>
1467
1468<p>Depending on properties of the target machine and the particular
1469<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswell84114752004-06-25 16:05:06 +0000[diff] [blame]1470ways. For example, it could be generated as a series of chained conditional
1471branches or with a lookup table.</p>
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1472
1473<h5>Example:</h5>
1474
1475<pre>
1476 <i>; Emulate a conditional br instruction</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]1477 %Val = <a href="#i_zext">zext</a> bool %value to int
Chris Lattnerc88c17b2004-02-24 04:54:45 +0000[diff] [blame]1478 switch int %Val, label %truedest [int 0, label %falsedest ]
1479
1480 <i>; Emulate an unconditional br instruction</i>
1481 switch uint 0, label %dest [ ]
1482
1483 <i>; Implement a jump table:</i>
1484 switch uint %val, label %otherwise [ uint 0, label %onzero
1485 uint 1, label %onone
1486 uint 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1487</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1488</div>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1489
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1490<!-- _______________________________________________________________________ -->
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1491<div class="doc_subsubsection">
1492 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1493</div>
1494
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1495<div class="doc_text">
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1496
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1497<h5>Syntax:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1498
1499<pre>
1500 &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]1501 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1502</pre>
1503
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1504<h5>Overview:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1505
1506<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1507function, with the possibility of control flow transfer to either the
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1508'<tt>normal</tt>' label or the
1509'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1510"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1511"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswelle4c57cc2005-05-12 16:52:32 +0000[diff] [blame]1512href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1513continued at the dynamically nearest "exception" label.</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1514
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1515<h5>Arguments:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1516
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1517<p>This instruction requires several arguments:</p>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1518
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1519<ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1520 <li>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]1521 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1522 convention</a> the call should use. If none is specified, the call defaults
1523 to using C calling conventions.
1524 </li>
1525 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1526 function value being invoked. In most cases, this is a direct function
1527 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1528 an arbitrary pointer to function value.
1529 </li>
1530
1531 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1532 function to be invoked. </li>
1533
1534 <li>'<tt>function args</tt>': argument list whose types match the function
1535 signature argument types. If the function signature indicates the function
1536 accepts a variable number of arguments, the extra arguments can be
1537 specified. </li>
1538
1539 <li>'<tt>normal label</tt>': the label reached when the called function
1540 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1541
1542 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1543 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1544
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1545</ol>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1546
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1547<h5>Semantics:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1548
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1549<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1550href="#i_call">call</a></tt>' instruction in most regards. The primary
1551difference is that it establishes an association with a label, which is used by
1552the runtime library to unwind the stack.</p>
1553
1554<p>This instruction is used in languages with destructors to ensure that proper
1555cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1556exception. Additionally, this is important for implementation of
1557'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1558
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1559<h5>Example:</h5>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1560<pre>
1561 %retval = invoke int %Test(int 15) to label %Continue
Chris Lattner76b8a332006-05-14 18:23:06 +0000[diff] [blame]1562 unwind label %TestCleanup <i>; {int}:retval set</i>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]1563 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
Chris Lattner76b8a332006-05-14 18:23:06 +0000[diff] [blame]1564 unwind label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1565</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1566</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1567
1568
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1569<!-- _______________________________________________________________________ -->
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1570
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1571<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1572Instruction</a> </div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1573
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1574<div class="doc_text">
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1575
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1576<h5>Syntax:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1577<pre>
1578 unwind
1579</pre>
1580
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1581<h5>Overview:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1582
1583<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1584at the first callee in the dynamic call stack which used an <a
1585href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1586primarily used to implement exception handling.</p>
1587
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1588<h5>Semantics:</h5>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1589
1590<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1591immediately halt. The dynamic call stack is then searched for the first <a
1592href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1593execution continues at the "exceptional" destination block specified by the
1594<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1595dynamic call chain, undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1596</div>
Chris Lattner35eca582004-10-16 18:04:13 +0000[diff] [blame]1597
1598<!-- _______________________________________________________________________ -->
1599
1600<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1601Instruction</a> </div>
1602
1603<div class="doc_text">
1604
1605<h5>Syntax:</h5>
1606<pre>
1607 unreachable
1608</pre>
1609
1610<h5>Overview:</h5>
1611
1612<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1613instruction is used to inform the optimizer that a particular portion of the
1614code is not reachable. This can be used to indicate that the code after a
1615no-return function cannot be reached, and other facts.</p>
1616
1617<h5>Semantics:</h5>
1618
1619<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1620</div>
1621
1622
1623
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1624<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1625<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1626<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1627<p>Binary operators are used to do most of the computation in a
1628program. They require two operands, execute an operation on them, and
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1629produce a single value. The operands might represent
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1630multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1631The result value of a binary operator is not
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1632necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1633<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1634</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1635<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1636<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1637Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1638<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1639<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1640<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]1641</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1642<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1643<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1644<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1645<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1646 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1647 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1648Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1649<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1650<p>The value produced is the integer or floating point sum of the two
1651operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1652<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1653<pre> &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1654</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1655</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1656<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1657<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1658Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1659<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1660<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1661<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]1662</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1663<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1664<p>The '<tt>sub</tt>' instruction returns the difference of its two
1665operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1666<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1667instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1668<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1669<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1670 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1671values.
1672This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1673Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1674<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1675<p>The value produced is the integer or floating point difference of
1676the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1677<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1678<pre> &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1679 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1680</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1681</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1682<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1683<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1684Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1685<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1686<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1687<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]1688</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1689<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1690<p>The '<tt>mul</tt>' instruction returns the product of its two
1691operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1692<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1693<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1694 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnera58561b2004-08-12 19:12:28 +0000[diff] [blame]1695values.
1696This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1697Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1698<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1699<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1700two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1701<p>There is no signed vs unsigned multiplication. The appropriate
1702action is taken based on the type of the operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1703<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1704<pre> &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1705</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1706</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1707<!-- _______________________________________________________________________ -->
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1708<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1709</a></div>
1710<div class="doc_text">
1711<h5>Syntax:</h5>
1712<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1713</pre>
1714<h5>Overview:</h5>
1715<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1716operands.</p>
1717<h5>Arguments:</h5>
1718<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1719<a href="#t_integer">integer</a> values. Both arguments must have identical
1720types. This instruction can also take <a href="#t_packed">packed</a> versions
1721of the values in which case the elements must be integers.</p>
1722<h5>Semantics:</h5>
1723<p>The value produced is the unsigned integer quotient of the two operands. This
1724instruction always performs an unsigned division operation, regardless of
1725whether the arguments are unsigned or not.</p>
1726<h5>Example:</h5>
1727<pre> &lt;result&gt; = udiv uint 4, %var <i>; yields {uint}:result = 4 / %var</i>
1728</pre>
1729</div>
1730<!-- _______________________________________________________________________ -->
1731<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1732</a> </div>
1733<div class="doc_text">
1734<h5>Syntax:</h5>
1735<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1736</pre>
1737<h5>Overview:</h5>
1738<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1739operands.</p>
1740<h5>Arguments:</h5>
1741<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1742<a href="#t_integer">integer</a> values. Both arguments must have identical
1743types. This instruction can also take <a href="#t_packed">packed</a> versions
1744of the values in which case the elements must be integers.</p>
1745<h5>Semantics:</h5>
1746<p>The value produced is the signed integer quotient of the two operands. This
1747instruction always performs a signed division operation, regardless of whether
1748the arguments are signed or not.</p>
1749<h5>Example:</h5>
1750<pre> &lt;result&gt; = sdiv int 4, %var <i>; yields {int}:result = 4 / %var</i>
1751</pre>
1752</div>
1753<!-- _______________________________________________________________________ -->
1754<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1755Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1756<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1757<h5>Syntax:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1758<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]1759</pre>
1760<h5>Overview:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1761<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1762operands.</p>
1763<h5>Arguments:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1764<p>The two arguments to the '<tt>div</tt>' instruction must be
1765<a href="#t_floating">floating point</a> values. Both arguments must have
1766identical types. This instruction can also take <a href="#t_packed">packed</a>
1767versions of the values in which case the elements must be floating point.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1768<h5>Semantics:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1769<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1770<h5>Example:</h5>
Reid Spencer1628cec2006-10-26 06:15:43 +0000[diff] [blame]1771<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]1772</pre>
1773</div>
1774<!-- _______________________________________________________________________ -->
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1775<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1776</div>
1777<div class="doc_text">
1778<h5>Syntax:</h5>
1779<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1780</pre>
1781<h5>Overview:</h5>
1782<p>The '<tt>urem</tt>' instruction returns the remainder from the
1783unsigned division of its two arguments.</p>
1784<h5>Arguments:</h5>
1785<p>The two arguments to the '<tt>urem</tt>' instruction must be
1786<a href="#t_integer">integer</a> values. Both arguments must have identical
1787types.</p>
1788<h5>Semantics:</h5>
1789<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1790This instruction always performs an unsigned division to get the remainder,
1791regardless of whether the arguments are unsigned or not.</p>
1792<h5>Example:</h5>
1793<pre> &lt;result&gt; = urem uint 4, %var <i>; yields {uint}:result = 4 % %var</i>
1794</pre>
1795
1796</div>
1797<!-- _______________________________________________________________________ -->
1798<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1799Instruction</a> </div>
1800<div class="doc_text">
1801<h5>Syntax:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1802<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]1803</pre>
1804<h5>Overview:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1805<p>The '<tt>srem</tt>' instruction returns the remainder from the
1806signed division of its two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1807<h5>Arguments:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1808<p>The two arguments to the '<tt>srem</tt>' instruction must be
1809<a href="#t_integer">integer</a> values. Both arguments must have identical
1810types.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1811<h5>Semantics:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1812<p>This instruction returns the <i>remainder</i> of a division (where the result
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1813has the same sign as the divisor), not the <i>modulus</i> (where the
1814result has the same sign as the dividend) of a value. For more
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]1815information about the difference, see <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1816 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1817Math Forum</a>.</p>
1818<h5>Example:</h5>
Reid Spencer0a783f72006-11-02 01:53:59 +0000[diff] [blame]1819<pre> &lt;result&gt; = srem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1820</pre>
1821
1822</div>
1823<!-- _______________________________________________________________________ -->
1824<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
1825Instruction</a> </div>
1826<div class="doc_text">
1827<h5>Syntax:</h5>
1828<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1829</pre>
1830<h5>Overview:</h5>
1831<p>The '<tt>frem</tt>' instruction returns the remainder from the
1832division of its two operands.</p>
1833<h5>Arguments:</h5>
1834<p>The two arguments to the '<tt>frem</tt>' instruction must be
1835<a href="#t_floating">floating point</a> values. Both arguments must have
1836identical types.</p>
1837<h5>Semantics:</h5>
1838<p>This instruction returns the <i>remainder</i> of a division.</p>
1839<h5>Example:</h5>
1840<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]1841</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1842</div>
Robert Bocchino7b81c752006-02-17 21:18:08 +0000[diff] [blame]1843
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1844<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1845<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1846Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1847<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1848<p>Bitwise binary operators are used to do various forms of
1849bit-twiddling in a program. They are generally very efficient
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]1850instructions and can commonly be strength reduced from other
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1851instructions. They require two operands, execute an operation on them,
1852and produce a single value. The resulting value of the bitwise binary
1853operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1854</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1855<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1856<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1857Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1858<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1859<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1860<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]1861</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1862<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1863<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1864its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1865<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1866<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1867 href="#t_integral">integral</a> values. Both arguments must have
1868identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1869<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1870<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1871<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1872<div style="align: center">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1873<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1874 <tbody>
1875 <tr>
1876 <td>In0</td>
1877 <td>In1</td>
1878 <td>Out</td>
1879 </tr>
1880 <tr>
1881 <td>0</td>
1882 <td>0</td>
1883 <td>0</td>
1884 </tr>
1885 <tr>
1886 <td>0</td>
1887 <td>1</td>
1888 <td>0</td>
1889 </tr>
1890 <tr>
1891 <td>1</td>
1892 <td>0</td>
1893 <td>0</td>
1894 </tr>
1895 <tr>
1896 <td>1</td>
1897 <td>1</td>
1898 <td>1</td>
1899 </tr>
1900 </tbody>
1901</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1902</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1903<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1904<pre> &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 &amp; %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1905 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1906 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1907</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1908</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1909<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1910<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1911<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1912<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1913<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]1914</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1915<h5>Overview:</h5>
1916<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1917or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1918<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1919<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1920 href="#t_integral">integral</a> values. Both arguments must have
1921identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1922<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1923<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1924<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1925<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1926<table border="1" cellspacing="0" cellpadding="4">
1927 <tbody>
1928 <tr>
1929 <td>In0</td>
1930 <td>In1</td>
1931 <td>Out</td>
1932 </tr>
1933 <tr>
1934 <td>0</td>
1935 <td>0</td>
1936 <td>0</td>
1937 </tr>
1938 <tr>
1939 <td>0</td>
1940 <td>1</td>
1941 <td>1</td>
1942 </tr>
1943 <tr>
1944 <td>1</td>
1945 <td>0</td>
1946 <td>1</td>
1947 </tr>
1948 <tr>
1949 <td>1</td>
1950 <td>1</td>
1951 <td>1</td>
1952 </tr>
1953 </tbody>
1954</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1955</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1956<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1957<pre> &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1958 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1959 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1960</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1961</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1962<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1963<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1964Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1965<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1966<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1967<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]1968</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1969<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1970<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1971or of its two operands. The <tt>xor</tt> is used to implement the
1972"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1973<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1974<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1975 href="#t_integral">integral</a> values. Both arguments must have
1976identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1977<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1978<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1979<p> </p>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]1980<div style="align: center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1981<table border="1" cellspacing="0" cellpadding="4">
1982 <tbody>
1983 <tr>
1984 <td>In0</td>
1985 <td>In1</td>
1986 <td>Out</td>
1987 </tr>
1988 <tr>
1989 <td>0</td>
1990 <td>0</td>
1991 <td>0</td>
1992 </tr>
1993 <tr>
1994 <td>0</td>
1995 <td>1</td>
1996 <td>1</td>
1997 </tr>
1998 <tr>
1999 <td>1</td>
2000 <td>0</td>
2001 <td>1</td>
2002 </tr>
2003 <tr>
2004 <td>1</td>
2005 <td>1</td>
2006 <td>0</td>
2007 </tr>
2008 </tbody>
2009</table>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]2010</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2011<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2012<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2013<pre> &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2014 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
2015 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]2016 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2017</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2018</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2019<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2020<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2021Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2022<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2023<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2024<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2025</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2026<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2027<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2028the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2029<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2030<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2031 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
2032type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2033<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2034<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]2035<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2036<pre> &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 &lt;&lt; %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2037 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
2038 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
2039</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2040</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2041<!-- _______________________________________________________________________ -->
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2042<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2043Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2044<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2045<h5>Syntax:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2046<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2047</pre>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2048
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2049<h5>Overview:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2050<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2051operand shifted to the right a specified number of bits.</p>
2052
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2053<h5>Arguments:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2054<p>The first argument to the '<tt>lshr</tt>' instruction must be an <a
2055 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>' type.</p>
2056
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2057<h5>Semantics:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2058<p>This instruction always performs a logical shift right operation, regardless
2059of whether the arguments are unsigned or not. The <tt>var2</tt> most significant
2060bits will be filled with zero bits after the shift.</p>
2061
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2062<h5>Example:</h5>
Reid Spencer3822ff52006-11-08 06:47:33 +0000[diff] [blame]2063<pre>
2064 &lt;result&gt; = lshr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
2065 &lt;result&gt; = lshr int 4, ubyte 2 <i>; yields {uint}:result = 1</i>
2066 &lt;result&gt; = lshr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
2067 &lt;result&gt; = lshr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = 0x7FFFFFFF </i>
2068</pre>
2069</div>
2070
2071<!-- ======================================================================= -->
2072<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2073Instruction</a> </div>
2074<div class="doc_text">
2075
2076<h5>Syntax:</h5>
2077<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
2078</pre>
2079
2080<h5>Overview:</h5>
2081<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2082operand shifted to the right a specified number of bits.</p>
2083
2084<h5>Arguments:</h5>
2085<p>The first argument to the '<tt>ashr</tt>' instruction must be an
2086<a href="#t_integer">integer</a> type. The second argument must be an
2087'<tt>ubyte</tt>' type.</p>
2088
2089<h5>Semantics:</h5>
2090<p>This instruction always performs an arithmetic shift right operation,
2091regardless of whether the arguments are signed or not. The <tt>var2</tt> most
2092significant bits will be filled with the sign bit of <tt>var1</tt>.</p>
2093
2094<h5>Example:</h5>
2095<pre>
2096 &lt;result&gt; = ashr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
2097 &lt;result&gt; = ashr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
2098 &lt;result&gt; = ashr ubyte 4, ubyte 3 <i>; yields {ubyte}:result = 0</i>
2099 &lt;result&gt; = ashr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2100</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2101</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2102
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2103<!-- ======================================================================= -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2104<div class="doc_subsection">
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2105 <a name="vectorops">Vector Operations</a>
2106</div>
2107
2108<div class="doc_text">
2109
2110<p>LLVM supports several instructions to represent vector operations in a
2111target-independent manner. This instructions cover the element-access and
2112vector-specific operations needed to process vectors effectively. While LLVM
2113does directly support these vector operations, many sophisticated algorithms
2114will want to use target-specific intrinsics to take full advantage of a specific
2115target.</p>
2116
2117</div>
2118
2119<!-- _______________________________________________________________________ -->
2120<div class="doc_subsubsection">
2121 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2122</div>
2123
2124<div class="doc_text">
2125
2126<h5>Syntax:</h5>
2127
2128<pre>
2129 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, uint &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
2130</pre>
2131
2132<h5>Overview:</h5>
2133
2134<p>
2135The '<tt>extractelement</tt>' instruction extracts a single scalar
2136element from a packed vector at a specified index.
2137</p>
2138
2139
2140<h5>Arguments:</h5>
2141
2142<p>
2143The first operand of an '<tt>extractelement</tt>' instruction is a
2144value of <a href="#t_packed">packed</a> type. The second operand is
2145an index indicating the position from which to extract the element.
2146The index may be a variable.</p>
2147
2148<h5>Semantics:</h5>
2149
2150<p>
2151The result is a scalar of the same type as the element type of
2152<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2153<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2154results are undefined.
2155</p>
2156
2157<h5>Example:</h5>
2158
2159<pre>
2160 %result = extractelement &lt;4 x int&gt; %vec, uint 0 <i>; yields int</i>
2161</pre>
2162</div>
2163
2164
2165<!-- _______________________________________________________________________ -->
2166<div class="doc_subsubsection">
2167 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2168</div>
2169
2170<div class="doc_text">
2171
2172<h5>Syntax:</h5>
2173
2174<pre>
2175 &lt;result&gt; = insertelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, &lt;ty&gt; &lt;elt&gt, uint &lt;idx&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
2176</pre>
2177
2178<h5>Overview:</h5>
2179
2180<p>
2181The '<tt>insertelement</tt>' instruction inserts a scalar
2182element into a packed vector at a specified index.
2183</p>
2184
2185
2186<h5>Arguments:</h5>
2187
2188<p>
2189The first operand of an '<tt>insertelement</tt>' instruction is a
2190value of <a href="#t_packed">packed</a> type. The second operand is a
2191scalar value whose type must equal the element type of the first
2192operand. The third operand is an index indicating the position at
2193which to insert the value. The index may be a variable.</p>
2194
2195<h5>Semantics:</h5>
2196
2197<p>
2198The result is a packed vector of the same type as <tt>val</tt>. Its
2199element values are those of <tt>val</tt> except at position
2200<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2201exceeds the length of <tt>val</tt>, the results are undefined.
2202</p>
2203
2204<h5>Example:</h5>
2205
2206<pre>
2207 %result = insertelement &lt;4 x int&gt; %vec, int 1, uint 0 <i>; yields &lt;4 x int&gt;</i>
2208</pre>
2209</div>
2210
2211<!-- _______________________________________________________________________ -->
2212<div class="doc_subsubsection">
2213 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2214</div>
2215
2216<div class="doc_text">
2217
2218<h5>Syntax:</h5>
2219
2220<pre>
2221 &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 uint&gt; &lt;mask&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
2222</pre>
2223
2224<h5>Overview:</h5>
2225
2226<p>
2227The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2228from two input vectors, returning a vector of the same type.
2229</p>
2230
2231<h5>Arguments:</h5>
2232
2233<p>
2234The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2235with types that match each other and types that match the result of the
2236instruction. The third argument is a shuffle mask, which has the same number
2237of elements as the other vector type, but whose element type is always 'uint'.
2238</p>
2239
2240<p>
2241The shuffle mask operand is required to be a constant vector with either
2242constant integer or undef values.
2243</p>
2244
2245<h5>Semantics:</h5>
2246
2247<p>
2248The elements of the two input vectors are numbered from left to right across
2249both of the vectors. The shuffle mask operand specifies, for each element of
2250the result vector, which element of the two input registers the result element
2251gets. The element selector may be undef (meaning "don't care") and the second
2252operand may be undef if performing a shuffle from only one vector.
2253</p>
2254
2255<h5>Example:</h5>
2256
2257<pre>
2258 %result = shufflevector &lt;4 x int&gt; %v1, &lt;4 x int&gt; %v2,
2259 &lt;4 x uint&gt; &lt;uint 0, uint 4, uint 1, uint 5&gt; <i>; yields &lt;4 x int&gt;</i>
2260 %result = shufflevector &lt;4 x int&gt; %v1, &lt;4 x int&gt; undef,
2261 &lt;4 x uint&gt; &lt;uint 0, uint 1, uint 2, uint 3&gt; <i>; yields &lt;4 x int&gt;</i> - Identity shuffle.
2262</pre>
2263</div>
2264
Tanya Lattner09474292006-04-14 19:24:33 +0000[diff] [blame]2265
Chris Lattner3df241e2006-04-08 23:07:04 +0000[diff] [blame]2266<!-- ======================================================================= -->
2267<div class="doc_subsection">
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2268 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2269</div>
2270
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2271<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2272
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2273<p>A key design point of an SSA-based representation is how it
2274represents memory. In LLVM, no memory locations are in SSA form, which
2275makes things very simple. This section describes how to read, write,
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2276allocate, and free memory in LLVM.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2277
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2278</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2279
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2280<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2281<div class="doc_subsubsection">
2282 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2283</div>
2284
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2285<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2286
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2287<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2288
2289<pre>
2290 &lt;result&gt; = malloc &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2291</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2292
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2293<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2294
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2295<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2296heap and returns a pointer to it.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2297
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2298<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2299
2300<p>The '<tt>malloc</tt>' instruction allocates
2301<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswell6e4ca612004-02-24 16:13:56 +0000[diff] [blame]2302bytes of memory from the operating system and returns a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2303appropriate type to the program. If "NumElements" is specified, it is the
2304number of elements allocated. If an alignment is specified, the value result
2305of the allocation is guaranteed to be aligned to at least that boundary. If
2306not specified, or if zero, the target can choose to align the allocation on any
2307convenient boundary.</p>
2308
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2309<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2310
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2311<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2312
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2313<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2314a pointer is returned.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2315
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2316<h5>Example:</h5>
2317
2318<pre>
2319 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
2320
2321 %size = <a href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2322 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
2323 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2324 %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
2325 %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2326</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2327</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2328
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2329<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2330<div class="doc_subsubsection">
2331 <a name="i_free">'<tt>free</tt>' Instruction</a>
2332</div>
2333
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2334<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2335
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2336<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2337
2338<pre>
2339 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2340</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2341
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2342<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2343
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2344<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2345memory heap to be reallocated in the future.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2346
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2347<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2348
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2349<p>'<tt>value</tt>' shall be a pointer value that points to a value
2350that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2351instruction.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2352
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2353<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2354
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2355<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2356after this instruction executes.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2357
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2358<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2359
2360<pre>
2361 %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2362 free [4 x ubyte]* %array
2363</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2364</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2365
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2366<!-- _______________________________________________________________________ -->
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2367<div class="doc_subsubsection">
2368 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2369</div>
2370
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2371<div class="doc_text">
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2372
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2373<h5>Syntax:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2374
2375<pre>
2376 &lt;result&gt; = alloca &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2377</pre>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2378
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2379<h5>Overview:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2380
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2381<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2382stack frame of the procedure that is live until the current function
2383returns to its caller.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2384
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2385<h5>Arguments:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2386
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]2387<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2388bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2389appropriate type to the program. If "NumElements" is specified, it is the
2390number of elements allocated. If an alignment is specified, the value result
2391of the allocation is guaranteed to be aligned to at least that boundary. If
2392not specified, or if zero, the target can choose to align the allocation on any
2393convenient boundary.</p>
2394
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2395<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2396
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2397<h5>Semantics:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2398
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2399<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2400memory is automatically released when the function returns. The '<tt>alloca</tt>'
2401instruction is commonly used to represent automatic variables that must
2402have an address available. When the function returns (either with the <tt><a
John Criswelldae2e932005-05-12 16:55:34 +0000[diff] [blame]2403 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]2404instructions), the memory is reclaimed.</p>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2405
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2406<h5>Example:</h5>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2407
2408<pre>
2409 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2410 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2411 %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
2412 %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2413</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2414</div>
Chris Lattner2cbdc452005-11-06 08:02:57 +0000[diff] [blame]2415
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2416<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2417<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2418Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2419<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2420<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2421<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]2422<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2423<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2424<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2425<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2426address from which to load. The pointer must point to a <a
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2427 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2428marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2429the number or order of execution of this <tt>load</tt> with other
2430volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2431instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2432<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2433<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2434<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2435<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
2436 <a
2437 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2438 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
2439</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2440</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2441<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2442<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2443Instruction</a> </div>
Reid Spencer035ab572006-11-09 21:18:01 +0000[diff] [blame]2444<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2445<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2446<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]2447 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]2448</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2449<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2450<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2451<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2452<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell0ec250c2005-10-24 16:17:18 +0000[diff] [blame]2453to 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]2454operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2455operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2456optimizer is not allowed to modify the number or order of execution of
2457this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2458 href="#i_store">store</a></tt> instructions.</p>
2459<h5>Semantics:</h5>
2460<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2461at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2462<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2463<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
2464 <a
2465 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2466 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
2467</pre>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2468</div>
2469
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2470<!-- _______________________________________________________________________ -->
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2471<div class="doc_subsubsection">
2472 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2473</div>
2474
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2475<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2476<h5>Syntax:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2477<pre>
2478 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2479</pre>
2480
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2481<h5>Overview:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2482
2483<p>
2484The '<tt>getelementptr</tt>' instruction is used to get the address of a
2485subelement of an aggregate data structure.</p>
2486
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2487<h5>Arguments:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2488
2489<p>This instruction takes a list of integer constants that indicate what
2490elements of the aggregate object to index to. The actual types of the arguments
2491provided depend on the type of the first pointer argument. The
2492'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2493levels of a structure or to a specific index in an array. When indexing into a
2494structure, only <tt>uint</tt>
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2495integer constants are allowed. When indexing into an array or pointer,
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]2496<tt>int</tt> and <tt>long</tt> and <tt>ulong</tt> indexes are allowed.</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2497
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2498<p>For example, let's consider a C code fragment and how it gets
2499compiled to LLVM:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2500
2501<pre>
2502 struct RT {
2503 char A;
2504 int B[10][20];
2505 char C;
2506 };
2507 struct ST {
2508 int X;
2509 double Y;
2510 struct RT Z;
2511 };
2512
2513 int *foo(struct ST *s) {
2514 return &amp;s[1].Z.B[5][13];
2515 }
2516</pre>
2517
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2518<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2519
2520<pre>
2521 %RT = type { sbyte, [10 x [20 x int]], sbyte }
2522 %ST = type { int, double, %RT }
2523
Brian Gaeke7283e7c2004-07-02 21:08:14 +0000[diff] [blame]2524 implementation
2525
2526 int* %foo(%ST* %s) {
2527 entry:
2528 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2529 ret int* %reg
2530 }
2531</pre>
2532
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2533<h5>Semantics:</h5>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2534
2535<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswellc1f786c2005-05-13 22:25:59 +0000[diff] [blame]2536on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]2537and <a href="#t_array">array</a> types require <tt>int</tt>,
Chris Lattnere53e5082004-06-03 22:57:15 +0000[diff] [blame]2538<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2539types require <tt>uint</tt> <b>constants</b>.</p>
2540
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2541<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2542type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
2543}</tt>' type, a structure. The second index indexes into the third element of
2544the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
2545sbyte }</tt>' type, another structure. The third index indexes into the second
2546element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
2547array. The two dimensions of the array are subscripted into, yielding an
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]2548'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2549to this element, thus computing a value of '<tt>int*</tt>' type.</p>
2550
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2551<p>Note that it is perfectly legal to index partially through a
2552structure, returning a pointer to an inner element. Because of this,
2553the LLVM code for the given testcase is equivalent to:</p>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2554
2555<pre>
Chris Lattnerd4f6b172005-03-07 22:13:59 +0000[diff] [blame]2556 int* %foo(%ST* %s) {
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2557 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
2558 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
2559 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
2560 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
2561 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
2562 ret int* %t5
2563 }
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2564</pre>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2565
2566<p>Note that it is undefined to access an array out of bounds: array and
2567pointer indexes must always be within the defined bounds of the array type.
2568The one exception for this rules is zero length arrays. These arrays are
2569defined to be accessible as variable length arrays, which requires access
2570beyond the zero'th element.</p>
2571
Chris Lattner884a9702006-08-15 00:45:58 +0000[diff] [blame]2572<p>The getelementptr instruction is often confusing. For some more insight
2573into how it works, see <a href="GetElementPtr.html">the getelementptr
2574FAQ</a>.</p>
2575
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]2576<h5>Example:</h5>
Chris Lattnere67a9512005-06-24 17:22:57 +0000[diff] [blame]2577
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2578<pre>
2579 <i>; yields [12 x ubyte]*:aptr</i>
2580 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
2581</pre>
Chris Lattnerf74d5c72004-04-05 01:30:49 +0000[diff] [blame]2582</div>
Reid Spencer47ce1792006-11-09 21:15:49 +0000[diff] [blame]2583
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]2584<!-- ======================================================================= -->
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2585<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2586</div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2587<div class="doc_text">
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]2588<p>The instructions in this category are the conversion instructions (casting)
2589which all take a single operand and a type. They perform various bit conversions
2590on the operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]2591</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2592
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2593<!-- _______________________________________________________________________ -->
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2594<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2595 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2596</div>
2597<div class="doc_text">
2598
2599<h5>Syntax:</h5>
2600<pre>
2601 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2602</pre>
2603
2604<h5>Overview:</h5>
2605<p>
2606The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2607</p>
2608
2609<h5>Arguments:</h5>
2610<p>
2611The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2612be an <a href="#t_integer">integer</a> type, and a type that specifies the size
2613and type of the result, which must be an <a href="#t_integral">integral</a>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2614type. The bit size of <tt>value</tt> must be larger than the bit size of
2615<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2616
2617<h5>Semantics:</h5>
2618<p>
2619The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2620and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2621larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2622It will always truncate bits.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2623
2624<h5>Example:</h5>
2625<pre>
2626 %X = trunc int 257 to ubyte <i>; yields ubyte:1</i>
2627 %Y = trunc int 123 to bool <i>; yields bool:true</i>
2628</pre>
2629</div>
2630
2631<!-- _______________________________________________________________________ -->
2632<div class="doc_subsubsection">
2633 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2634</div>
2635<div class="doc_text">
2636
2637<h5>Syntax:</h5>
2638<pre>
2639 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2640</pre>
2641
2642<h5>Overview:</h5>
2643<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2644<tt>ty2</tt>.</p>
2645
2646
2647<h5>Arguments:</h5>
2648<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
2649<a href="#t_integral">integral</a> type, and a type to cast it to, which must
2650also be of <a href="#t_integral">integral</a> type. The bit size of the
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2651<tt>value</tt> must be smaller than the bit size of the destination type,
2652<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2653
2654<h5>Semantics:</h5>
2655<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2656bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2657the operand and the type are the same size, no bit filling is done and the
2658cast is considered a <i>no-op cast</i> because no bits change (only the type
2659changes).</p>
2660
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2661<p>When zero extending from bool, the result will alwasy be either 0 or 1.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2662
2663<h5>Example:</h5>
2664<pre>
2665 %X = zext int 257 to ulong <i>; yields ulong:257</i>
2666 %Y = zext bool true to int <i>; yields int:1</i>
2667</pre>
2668</div>
2669
2670<!-- _______________________________________________________________________ -->
2671<div class="doc_subsubsection">
2672 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2673</div>
2674<div class="doc_text">
2675
2676<h5>Syntax:</h5>
2677<pre>
2678 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2679</pre>
2680
2681<h5>Overview:</h5>
2682<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2683
2684<h5>Arguments:</h5>
2685<p>
2686The '<tt>sext</tt>' instruction takes a value to cast, which must be of
2687<a href="#t_integral">integral</a> type, and a type to cast it to, which must
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2688also be of <a href="#t_integral">integral</a> type. The bit size of the
2689<tt>value</tt> must be smaller than the bit size of the destination type,
2690<tt>ty2</tt>.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2691
2692<h5>Semantics:</h5>
2693<p>
2694The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2695bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2696the type <tt>ty2</tt>. When the the operand and the type are the same size,
2697no bit filling is done and the cast is considered a <i>no-op cast</i> because
2698no bits change (only the type changes).</p>
2699
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2700<p>When sign extending from bool, the extension always results in -1 or 0.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2701
2702<h5>Example:</h5>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2703<pre>
2704 %X = sext sbyte -1 to ushort <i>; yields ushort:65535</i>
2705 %Y = sext bool true to int <i>; yields int:-1</i>
2706</pre>
2707</div>
2708
2709<!-- _______________________________________________________________________ -->
2710<div class="doc_subsubsection">
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2711 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2712</div>
2713
2714<div class="doc_text">
2715
2716<h5>Syntax:</h5>
2717
2718<pre>
2719 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2720</pre>
2721
2722<h5>Overview:</h5>
2723<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2724<tt>ty2</tt>.</p>
2725
2726
2727<h5>Arguments:</h5>
2728<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2729 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2730cast it to. The size of <tt>value</tt> must be larger than the size of
2731<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2732<i>no-op cast</i>.</p>
2733
2734<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2735<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2736<a href="#t_floating">floating point</a> type to a smaller
2737<a href="#t_floating">floating point</a> type. If the value cannot fit within
2738the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer3fa91b02006-11-09 21:48:10 +0000[diff] [blame]2739
2740<h5>Example:</h5>
2741<pre>
2742 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2743 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2744</pre>
2745</div>
2746
2747<!-- _______________________________________________________________________ -->
2748<div class="doc_subsubsection">
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2749 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2750</div>
2751<div class="doc_text">
2752
2753<h5>Syntax:</h5>
2754<pre>
2755 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2756</pre>
2757
2758<h5>Overview:</h5>
2759<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2760floating point value.</p>
2761
2762<h5>Arguments:</h5>
2763<p>The '<tt>fpext</tt>' instruction takes a
2764<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2765and a <a href="#t_floating">floating point</a> type to cast it to. The source
2766type must be smaller than the destination type.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2767
2768<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2769<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
2770<a href="t_floating">floating point</a> type to a larger
2771<a href="t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
2772used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]2773<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]2774
2775<h5>Example:</h5>
2776<pre>
2777 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2778 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2779</pre>
2780</div>
2781
2782<!-- _______________________________________________________________________ -->
2783<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2784 <a name="i_fp2uint">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2785</div>
2786<div class="doc_text">
2787
2788<h5>Syntax:</h5>
2789<pre>
2790 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2791</pre>
2792
2793<h5>Overview:</h5>
2794<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2795unsigned integer equivalent of type <tt>ty2</tt>.
2796</p>
2797
2798<h5>Arguments:</h5>
2799<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2800<a href="#t_floating">floating point</a> value, and a type to cast it to, which
2801must be an <a href="#t_integral">integral</a> type.</p>
2802
2803<h5>Semantics:</h5>
2804<p> The '<tt>fp2uint</tt>' instruction converts its
2805<a href="#t_floating">floating point</a> operand into the nearest (rounding
2806towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2807the results are undefined.</p>
2808
2809<p>When converting to bool, the conversion is done as a comparison against
2810zero. If the <tt>value</tt> was zero, the bool result will be <tt>false</tt>.
2811If the <tt>value</tt> was non-zero, the bool result will be <tt>true</tt>.</p>
2812
2813<h5>Example:</h5>
2814<pre>
2815 %X = fp2uint double 123.0 to int <i>; yields int:123</i>
2816 %Y = fp2uint float 1.0E+300 to bool <i>; yields bool:true</i>
2817 %X = fp2uint float 1.04E+17 to ubyte <i>; yields undefined:1</i>
2818</pre>
2819</div>
2820
2821<!-- _______________________________________________________________________ -->
2822<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2823 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2824</div>
2825<div class="doc_text">
2826
2827<h5>Syntax:</h5>
2828<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2829 &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]2830</pre>
2831
2832<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2833<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2834<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]2835</p>
2836
2837
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2838<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2839<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]2840<a href="#t_floating">floating point</a> value, and a type to cast it to, which
2841must also be an <a href="#t_integral">integral</a> type.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2842
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]2843<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2844<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2845<a href="#t_floating">floating point</a> operand into the nearest (rounding
2846towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
2847the results are undefined.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2848
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2849<p>When converting to bool, the conversion is done as a comparison against
2850zero. If the <tt>value</tt> was zero, the bool result will be <tt>false</tt>.
2851If the <tt>value</tt> was non-zero, the bool result will be <tt>true</tt>.</p>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2852
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]2853<h5>Example:</h5>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]2854<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2855 %X = fptosi double -123.0 to int <i>; yields int:-123</i>
2856 %Y = fptosi float 1.0E-247 to bool <i>; yields bool:true</i>
2857 %X = fptosi float 1.04E+17 to sbyte <i>; yields undefined:1</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2858</pre>
2859</div>
2860
2861<!-- _______________________________________________________________________ -->
2862<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2863 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2864</div>
2865<div class="doc_text">
2866
2867<h5>Syntax:</h5>
2868<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2869 &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]2870</pre>
2871
2872<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2873<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2874integer and converts that value to the <tt>ty2</tt> type.</p>
2875
2876
2877<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2878<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be an
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2879<a href="#t_integral">integral</a> value, and a type to cast it to, which must
2880be a <a href="#t_floating">floating point</a> type.</p>
2881
2882<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2883<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2884integer quantity and converts it to the corresponding floating point value. If
2885the value cannot fit in the floating point value, the results are undefined.</p>
2886
2887
2888<h5>Example:</h5>
2889<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2890 %X = uitofp int 257 to float <i>; yields float:257.0</i>
2891 %Y = uitofp sbyte -1 to double <i>; yields double:255.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2892</pre>
2893</div>
2894
2895<!-- _______________________________________________________________________ -->
2896<div class="doc_subsubsection">
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2897 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2898</div>
2899<div class="doc_text">
2900
2901<h5>Syntax:</h5>
2902<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2903 &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]2904</pre>
2905
2906<h5>Overview:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2907<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2908integer and converts that value to the <tt>ty2</tt> type.</p>
2909
2910<h5>Arguments:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2911<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be an
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2912<a href="#t_integral">integral</a> value, and a type to cast it to, which must be
2913a <a href="#t_floating">floating point</a> type.</p>
2914
2915<h5>Semantics:</h5>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2916<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2917integer quantity and converts it to the corresponding floating point value. If
2918the value cannot fit in the floating point value, the results are undefined.</p>
2919
2920<h5>Example:</h5>
2921<pre>
Reid Spencerd4448792006-11-09 23:03:26 +0000[diff] [blame]2922 %X = sitofp int 257 to float <i>; yields float:257.0</i>
2923 %Y = sitofp sbyte -1 to double <i>; yields double:-1.0</i>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]2924</pre>
2925</div>
2926
2927<!-- _______________________________________________________________________ -->
2928<div class="doc_subsubsection">
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]2929 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
2930</div>
2931<div class="doc_text">
2932
2933<h5>Syntax:</h5>
2934<pre>
2935 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2936</pre>
2937
2938<h5>Overview:</h5>
2939<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
2940the integer type <tt>ty2</tt>.</p>
2941
2942<h5>Arguments:</h5>
2943<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
2944must be a <a href="t_pointer">pointer</a> value, and a type to cast it to
2945<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
2946
2947<h5>Semantics:</h5>
2948<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
2949<tt>ty2</tt> by interpreting the pointer value as an integer and either
2950truncating or zero extending that value to the size of the integer type. If
2951<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
2952<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
2953are the same size, then nothing is done (<i>no-op cast</i>).</p>
2954
2955<h5>Example:</h5>
2956<pre>
2957 %X = ptrtoint int* %X to sbyte <i>; yields truncation on 32-bit</i>
2958 %Y = ptrtoint int* %x to ulong <i>; yields zero extend on 32-bit</i>
2959</pre>
2960</div>
2961
2962<!-- _______________________________________________________________________ -->
2963<div class="doc_subsubsection">
2964 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
2965</div>
2966<div class="doc_text">
2967
2968<h5>Syntax:</h5>
2969<pre>
2970 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2971</pre>
2972
2973<h5>Overview:</h5>
2974<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
2975a pointer type, <tt>ty2</tt>.</p>
2976
2977<h5>Arguments:</h5>
2978<p>The '<tt>inttoptr</tt>' instruction takes an <a href="i_integer">integer</a>
2979value to cast, and a type to cast it to, which must be a
2980<a href="#t_pointer">pointer</a> type. </tt>
2981
2982<h5>Semantics:</h5>
2983<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
2984<tt>ty2</tt> by applying either a zero extension or a truncation depending on
2985the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
2986size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
2987the size of a pointer then a zero extension is done. If they are the same size,
2988nothing is done (<i>no-op cast</i>).</p>
2989
2990<h5>Example:</h5>
2991<pre>
2992 %X = inttoptr int 255 to int* <i>; yields zero extend on 64-bit</i>
2993 %X = inttoptr int 255 to int* <i>; yields no-op on 32-bit </i>
2994 %Y = inttoptr short 0 to int* <i>; yields zero extend on 32-bit</i>
2995</pre>
2996</div>
2997
2998<!-- _______________________________________________________________________ -->
2999<div class="doc_subsubsection">
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3000 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3001</div>
3002<div class="doc_text">
3003
3004<h5>Syntax:</h5>
3005<pre>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3006 &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]3007</pre>
3008
3009<h5>Overview:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3010<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3011<tt>ty2</tt> without changing any bits.</p>
3012
3013<h5>Arguments:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3014<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3015a first class value, and a type to cast it to, which must also be a <a
3016 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
3017and the destination type, <tt>ty2</tt>, must be identical.</p>
3018
3019<h5>Semantics:</h5>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3020<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer72679252006-11-11 21:00:47 +0000[diff] [blame]3021<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3022this conversion. The conversion is done as if the <tt>value</tt> had been
3023stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3024converted to other pointer types with this instruction. To convert pointers to
3025other types, use the <a href="#i_inttoptr">inttoptr</a> or
3026<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer9dee3ac2006-11-08 01:11:31 +0000[diff] [blame]3027
3028<h5>Example:</h5>
3029<pre>
Reid Spencer5c0ef472006-11-11 23:08:07 +0000[diff] [blame]3030 %X = bitcast ubyte 255 to sbyte <i>; yields sbyte:-1</i>
3031 %Y = bitcast uint* %x to sint* <i>; yields sint*:%x</i>
3032 %Z = bitcast <2xint> %V to long; <i>; yields long: %V</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]3033</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3034</div>
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3035
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3036<!-- ======================================================================= -->
3037<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3038<div class="doc_text">
3039<p>The instructions in this category are the "miscellaneous"
3040instructions, which defy better classification.</p>
3041</div>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3042
3043<!-- _______________________________________________________________________ -->
3044<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3045</div>
3046<div class="doc_text">
3047<h5>Syntax:</h5>
3048<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
3049</pre>
3050<h5>Overview:</h5>
3051<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3052of its two integer operands.</p>
3053<h5>Arguments:</h5>
3054<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3055the condition code which indicates the kind of comparison to perform. It is not
3056a value, just a keyword. The possibilities for the condition code are:
3057<ol>
3058 <li><tt>eq</tt>: equal</li>
3059 <li><tt>ne</tt>: not equal </li>
3060 <li><tt>ugt</tt>: unsigned greater than</li>
3061 <li><tt>uge</tt>: unsigned greater or equal</li>
3062 <li><tt>ult</tt>: unsigned less than</li>
3063 <li><tt>ule</tt>: unsigned less or equal</li>
3064 <li><tt>sgt</tt>: signed greater than</li>
3065 <li><tt>sge</tt>: signed greater or equal</li>
3066 <li><tt>slt</tt>: signed less than</li>
3067 <li><tt>sle</tt>: signed less or equal</li>
3068</ol>
3069<p>The remaining two arguments must be of <a href="#t_integral">integral</a>,
3070<a href="#t_pointer">pointer</a> or a <a href="#t_packed">packed</a> integral
3071type. They must have identical types.</p>
3072<h5>Semantics:</h5>
3073<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3074the condition code given as <tt>cond</tt>. The comparison performed always
3075yields a <a href="#t_bool">bool</a> result, as follows:
3076<ol>
3077 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3078 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3079 </li>
3080 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3081 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3082 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3083 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3084 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3085 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3086 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3087 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3088 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3089 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3090 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3091 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3092 <li><tt>sge</tt>: interprets the operands as signed values and yields
3093 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3094 <li><tt>slt</tt>: interprets the operands as signed values and yields
3095 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3096 <li><tt>sle</tt>: interprets the operands as signed values and yields
3097 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3098 </li>
3099</ol>
3100<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3101values are treated as integers and then compared.</p>
3102<p>If the operands are <a href="#t_packed">packed</a> typed, the elements of
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3103the vector are compared in turn and the predicate must hold for all
3104elements.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3105
3106<h5>Example:</h5>
3107<pre> &lt;result&gt; = icmp eq int 4, 5 <i>; yields: result=false</i>
3108 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3109 &lt;result&gt; = icmp ult short 4, 5 <i>; yields: result=true</i>
3110 &lt;result&gt; = icmp sgt sbyte 4, 5 <i>; yields: result=false</i>
3111 &lt;result&gt; = icmp ule sbyte -4, 5 <i>; yields: result=false</i>
3112 &lt;result&gt; = icmp sge sbyte 4, 5 <i>; yields: result=false</i>
3113</pre>
3114</div>
3115
3116<!-- _______________________________________________________________________ -->
3117<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3118</div>
3119<div class="doc_text">
3120<h5>Syntax:</h5>
3121<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
3122</pre>
3123<h5>Overview:</h5>
3124<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3125of its floating point operands.</p>
3126<h5>Arguments:</h5>
3127<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3128the condition code which indicates the kind of comparison to perform. It is not
3129a value, just a keyword. The possibilities for the condition code are:
3130<ol>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3131 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3132 <li><tt>oeq</tt>: ordered and equal</li>
3133 <li><tt>ogt</tt>: ordered and greater than </li>
3134 <li><tt>oge</tt>: ordered and greater than or equal</li>
3135 <li><tt>olt</tt>: ordered and less than </li>
3136 <li><tt>ole</tt>: ordered and less than or equal</li>
3137 <li><tt>one</tt>: ordered and not equal</li>
3138 <li><tt>ord</tt>: ordered (no nans)</li>
3139 <li><tt>ueq</tt>: unordered or equal</li>
3140 <li><tt>ugt</tt>: unordered or greater than </li>
3141 <li><tt>uge</tt>: unordered or greater than or equal</li>
3142 <li><tt>ult</tt>: unordered or less than </li>
3143 <li><tt>ule</tt>: unordered or less than or equal</li>
3144 <li><tt>une</tt>: unordered or not equal</li>
3145 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3146 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3147</ol>
3148<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be of
3149<a href="#t_floating">floating point</a>, or a <a href="#t_packed">packed</a>
3150floating point type. They must have identical types.</p>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3151<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3152<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3153<h5>Semantics:</h5>
3154<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3155the condition code given as <tt>cond</tt>. The comparison performed always
3156yields a <a href="#t_bool">bool</a> result, as follows:
3157<ol>
3158 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3159 <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]3160 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3161 <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]3162 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3163 <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]3164 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3165 <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]3166 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3167 <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]3168 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3169 <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]3170 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3171 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3172 <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]3173 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3174 <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]3175 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3176 <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]3177 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3178 <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]3179 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3180 <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]3181 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3182 <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]3183 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3184 <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]3185 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3186</ol>
3187<p>If the operands are <a href="#t_packed">packed</a> typed, the elements of
3188the vector are compared in turn and the predicate must hold for all elements.
Reid Spencerb7f26282006-11-19 03:00:14 +0000[diff] [blame]3189</p>
Reid Spencerf3a70a62006-11-18 21:50:54 +0000[diff] [blame]3190
3191<h5>Example:</h5>
3192<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3193 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3194 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3195 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3196</pre>
3197</div>
3198
Reid Spencer2fd21e62006-11-08 01:18:52 +0000[diff] [blame]3199<!-- _______________________________________________________________________ -->
3200<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3201Instruction</a> </div>
3202<div class="doc_text">
3203<h5>Syntax:</h5>
3204<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3205<h5>Overview:</h5>
3206<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3207the SSA graph representing the function.</p>
3208<h5>Arguments:</h5>
3209<p>The type of the incoming values are specified with the first type
3210field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3211as arguments, with one pair for each predecessor basic block of the
3212current block. Only values of <a href="#t_firstclass">first class</a>
3213type may be used as the value arguments to the PHI node. Only labels
3214may be used as the label arguments.</p>
3215<p>There must be no non-phi instructions between the start of a basic
3216block and the PHI instructions: i.e. PHI instructions must be first in
3217a basic block.</p>
3218<h5>Semantics:</h5>
3219<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3220value specified by the parameter, depending on which basic block we
3221came from in the last <a href="#terminators">terminator</a> instruction.</p>
3222<h5>Example:</h5>
3223<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre>
3224</div>
3225
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3226<!-- _______________________________________________________________________ -->
3227<div class="doc_subsubsection">
3228 <a name="i_select">'<tt>select</tt>' Instruction</a>
3229</div>
3230
3231<div class="doc_text">
3232
3233<h5>Syntax:</h5>
3234
3235<pre>
3236 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
3237</pre>
3238
3239<h5>Overview:</h5>
3240
3241<p>
3242The '<tt>select</tt>' instruction is used to choose one value based on a
3243condition, without branching.
3244</p>
3245
3246
3247<h5>Arguments:</h5>
3248
3249<p>
3250The '<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.
3251</p>
3252
3253<h5>Semantics:</h5>
3254
3255<p>
3256If the boolean condition evaluates to true, the instruction returns the first
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3257value argument; otherwise, it returns the second value argument.
Chris Lattnercc37aae2004-03-12 05:50:16 +0000[diff] [blame]3258</p>
3259
3260<h5>Example:</h5>
3261
3262<pre>
3263 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
3264</pre>
3265</div>
3266
Robert Bocchino05ccd702006-01-15 20:48:27 +0000[diff] [blame]3267
3268<!-- _______________________________________________________________________ -->
3269<div class="doc_subsubsection">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3270 <a name="i_call">'<tt>call</tt>' Instruction</a>
3271</div>
3272
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3273<div class="doc_text">
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3274
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3275<h5>Syntax:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3276<pre>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3277 &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]3278</pre>
3279
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3280<h5>Overview:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3281
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3282<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3283
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3284<h5>Arguments:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3285
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3286<p>This instruction requires several arguments:</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3287
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3288<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3289 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3290 <p>The optional "tail" marker indicates whether the callee function accesses
3291 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3292 function call is eligible for tail call optimization. Note that calls may
3293 be marked "tail" even if they do not occur before a <a
3294 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3295 </li>
3296 <li>
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3297 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
3298 convention</a> the call should use. If none is specified, the call defaults
3299 to using C calling conventions.
3300 </li>
3301 <li>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3302 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3303 being invoked. The argument types must match the types implied by this
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3304 signature. This type can be omitted if the function is not varargs and
3305 if the function type does not return a pointer to a function.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3306 </li>
3307 <li>
3308 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3309 be invoked. In most cases, this is a direct function invocation, but
3310 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3311 to function value.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3312 </li>
3313 <li>
3314 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencera7e302a2005-05-01 22:22:57 +0000[diff] [blame]3315 function signature argument types. All arguments must be of
3316 <a href="#t_firstclass">first class</a> type. If the function signature
3317 indicates the function accepts a variable number of arguments, the extra
3318 arguments can be specified.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3319 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]3320</ol>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3321
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3322<h5>Semantics:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3323
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3324<p>The '<tt>call</tt>' instruction is used to cause control flow to
3325transfer to a specified function, with its incoming arguments bound to
3326the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3327instruction in the called function, control flow continues with the
3328instruction after the function call, and the return value of the
3329function is bound to the result argument. This is a simpler case of
3330the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3331
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3332<h5>Example:</h5>
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3333
3334<pre>
3335 %retval = call int %test(int %argc)
3336 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
3337 %X = tail call int %foo()
Chris Lattnerbad10ee2005-05-06 22:57:40 +0000[diff] [blame]3338 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattner2bff5242005-05-06 05:47:36 +0000[diff] [blame]3339</pre>
3340
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3341</div>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3342
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3343<!-- _______________________________________________________________________ -->
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3344<div class="doc_subsubsection">
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3345 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3346</div>
3347
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3348<div class="doc_text">
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3349
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3350<h5>Syntax:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3351
3352<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3353 &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]3354</pre>
3355
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3356<h5>Overview:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3357
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3358<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3359the "variable argument" area of a function call. It is used to implement the
3360<tt>va_arg</tt> macro in C.</p>
3361
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3362<h5>Arguments:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3363
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3364<p>This instruction takes a <tt>va_list*</tt> value and the type of
3365the argument. It returns a value of the specified argument type and
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3366increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3367actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3368
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3369<h5>Semantics:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3370
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3371<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3372type from the specified <tt>va_list</tt> and causes the
3373<tt>va_list</tt> to point to the next argument. For more information,
3374see the variable argument handling <a href="#int_varargs">Intrinsic
3375Functions</a>.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3376
3377<p>It is legal for this instruction to be called in a function which does not
3378take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3379function.</p>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3380
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3381<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3382href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3383argument.</p>
3384
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]3385<h5>Example:</h5>
Chris Lattnere19d7a72004-09-27 21:51:25 +0000[diff] [blame]3386
3387<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3388
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3389</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3390
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3391<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3392<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3393<!-- *********************************************************************** -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3394
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3395<div class="doc_text">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3396
3397<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3398well known names and semantics and are required to follow certain
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3399restrictions. Overall, these instructions represent an extension mechanism for
3400the LLVM language that does not require changing all of the transformations in
3401LLVM to add to the language (or the bytecode reader/writer, the parser,
3402etc...).</p>
3403
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3404<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3405prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3406this. Intrinsic functions must always be external functions: you cannot define
3407the body of intrinsic functions. Intrinsic functions may only be used in call
3408or invoke instructions: it is illegal to take the address of an intrinsic
3409function. Additionally, because intrinsic functions are part of the LLVM
3410language, it is required that they all be documented here if any are added.</p>
3411
3412
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3413<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner590cff32005-05-11 03:35:57 +0000[diff] [blame]3414href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3415</p>
3416
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3417</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3418
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3419<!-- ======================================================================= -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3420<div class="doc_subsection">
3421 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3422</div>
3423
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3424<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3425
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3426<p>Variable argument support is defined in LLVM with the <a
Chris Lattnerfb6977d2006-01-13 23:26:01 +0000[diff] [blame]3427 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3428intrinsic functions. These functions are related to the similarly
3429named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3430
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3431<p>All of these functions operate on arguments that use a
3432target-specific value type "<tt>va_list</tt>". The LLVM assembly
3433language reference manual does not define what this type is, so all
3434transformations should be prepared to handle intrinsics with any type
3435used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3436
Chris Lattner374ab302006-05-15 17:26:46 +0000[diff] [blame]3437<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]3438instruction and the variable argument handling intrinsic functions are
3439used.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3440
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3441<pre>
3442int %test(int %X, ...) {
3443 ; Initialize variable argument processing
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3444 %ap = alloca sbyte*
3445 call void %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3446
3447 ; Read a single integer argument
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3448 %tmp = va_arg sbyte** %ap, int
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3449
3450 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3451 %aq = alloca sbyte*
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]3452 call void %<a href="#i_va_copy">llvm.va_copy</a>(sbyte** %aq, sbyte** %ap)
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3453 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3454
3455 ; Stop processing of arguments.
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3456 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3457 ret int %tmp
3458}
3459</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3460</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3461
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3462<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3463<div class="doc_subsubsection">
3464 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3465</div>
3466
3467
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3468<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3469<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3470<pre> declare void %llvm.va_start(&lt;va_list&gt;* &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3471<h5>Overview:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3472<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3473<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3474href="#i_va_arg">va_arg</a></tt>.</p>
3475
3476<h5>Arguments:</h5>
3477
3478<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3479
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3480<h5>Semantics:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3481
3482<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3483macro available in C. In a target-dependent way, it initializes the
3484<tt>va_list</tt> element the argument points to, so that the next call to
3485<tt>va_arg</tt> will produce the first variable argument passed to the function.
3486Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3487last argument of the function, the compiler can figure that out.</p>
3488
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3489</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3490
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3491<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3492<div class="doc_subsubsection">
3493 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3494</div>
3495
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3496<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3497<h5>Syntax:</h5>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3498<pre> declare void %llvm.va_end(&lt;va_list*&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3499<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]3500<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
3501which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
3502or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3503<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3504<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3505<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3506<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]3507macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
3508Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
3509 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
3510with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3511</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3512
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3513<!-- _______________________________________________________________________ -->
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3514<div class="doc_subsubsection">
3515 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3516</div>
3517
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3518<div class="doc_text">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3519
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3520<h5>Syntax:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3521
3522<pre>
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3523 declare void %llvm.va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
Andrew Lenharthd0a4c622005-06-22 20:38:11 +0000[diff] [blame]3524 &lt;va_list&gt;* &lt;srcarglist&gt;)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3525</pre>
3526
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3527<h5>Overview:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3528
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3529<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3530the source argument list to the destination argument list.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3531
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3532<h5>Arguments:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3533
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3534<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]3535The 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]3536
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3537
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]3538<h5>Semantics:</h5>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3539
Andrew Lenharth8bf607a2005-06-18 18:28:17 +0000[diff] [blame]3540<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3541available in C. In a target-dependent way, it copies the source
3542<tt>va_list</tt> element into the destination list. This intrinsic is necessary
3543because 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]3544arbitrarily complex and require memory allocation, for example.</p>
3545
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]3546</div>
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]3547
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3548<!-- ======================================================================= -->
3549<div class="doc_subsection">
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3550 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3551</div>
3552
3553<div class="doc_text">
3554
3555<p>
3556LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3557Collection</a> requires the implementation and generation of these intrinsics.
3558These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
3559stack</a>, as well as garbage collector implementations that require <a
3560href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
3561Front-ends for type-safe garbage collected languages should generate these
3562intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3563href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3564</p>
3565</div>
3566
3567<!-- _______________________________________________________________________ -->
3568<div class="doc_subsubsection">
3569 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3570</div>
3571
3572<div class="doc_text">
3573
3574<h5>Syntax:</h5>
3575
3576<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3577 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3578</pre>
3579
3580<h5>Overview:</h5>
3581
John Criswell9e2485c2004-12-10 15:51:16 +0000[diff] [blame]3582<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]3583the code generator, and allows some metadata to be associated with it.</p>
3584
3585<h5>Arguments:</h5>
3586
3587<p>The first argument specifies the address of a stack object that contains the
3588root pointer. The second pointer (which must be either a constant or a global
3589value address) contains the meta-data to be associated with the root.</p>
3590
3591<h5>Semantics:</h5>
3592
3593<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3594location. At compile-time, the code generator generates information to allow
3595the runtime to find the pointer at GC safe points.
3596</p>
3597
3598</div>
3599
3600
3601<!-- _______________________________________________________________________ -->
3602<div class="doc_subsubsection">
3603 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
3604</div>
3605
3606<div class="doc_text">
3607
3608<h5>Syntax:</h5>
3609
3610<pre>
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3611 declare sbyte* %llvm.gcread(sbyte* %ObjPtr, sbyte** %Ptr)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3612</pre>
3613
3614<h5>Overview:</h5>
3615
3616<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3617locations, allowing garbage collector implementations that require read
3618barriers.</p>
3619
3620<h5>Arguments:</h5>
3621
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3622<p>The second argument is the address to read from, which should be an address
3623allocated from the garbage collector. The first object is a pointer to the
3624start of the referenced object, if needed by the language runtime (otherwise
3625null).</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3626
3627<h5>Semantics:</h5>
3628
3629<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3630instruction, but may be replaced with substantially more complex code by the
3631garbage collector runtime, as needed.</p>
3632
3633</div>
3634
3635
3636<!-- _______________________________________________________________________ -->
3637<div class="doc_subsubsection">
3638 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
3639</div>
3640
3641<div class="doc_text">
3642
3643<h5>Syntax:</h5>
3644
3645<pre>
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3646 declare void %llvm.gcwrite(sbyte* %P1, sbyte* %Obj, sbyte** %P2)
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3647</pre>
3648
3649<h5>Overview:</h5>
3650
3651<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3652locations, allowing garbage collector implementations that require write
3653barriers (such as generational or reference counting collectors).</p>
3654
3655<h5>Arguments:</h5>
3656
Chris Lattner80626e92006-03-14 20:02:51 +0000[diff] [blame]3657<p>The first argument is the reference to store, the second is the start of the
3658object to store it to, and the third is the address of the field of Obj to
3659store to. If the runtime does not require a pointer to the object, Obj may be
3660null.</p>
Chris Lattnerd7923912004-05-23 21:06:01 +0000[diff] [blame]3661
3662<h5>Semantics:</h5>
3663
3664<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3665instruction, but may be replaced with substantially more complex code by the
3666garbage collector runtime, as needed.</p>
3667
3668</div>
3669
3670
3671
3672<!-- ======================================================================= -->
3673<div class="doc_subsection">
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3674 <a name="int_codegen">Code Generator Intrinsics</a>
3675</div>
3676
3677<div class="doc_text">
3678<p>
3679These intrinsics are provided by LLVM to expose special features that may only
3680be implemented with code generator support.
3681</p>
3682
3683</div>
3684
3685<!-- _______________________________________________________________________ -->
3686<div class="doc_subsubsection">
3687 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
3688</div>
3689
3690<div class="doc_text">
3691
3692<h5>Syntax:</h5>
3693<pre>
Chris Lattnerfcf39d42006-01-13 01:20:27 +0000[diff] [blame]3694 declare sbyte *%llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3695</pre>
3696
3697<h5>Overview:</h5>
3698
3699<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3700The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3701target-specific value indicating the return address of the current function
3702or one of its callers.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3703</p>
3704
3705<h5>Arguments:</h5>
3706
3707<p>
3708The argument to this intrinsic indicates which function to return the address
3709for. Zero indicates the calling function, one indicates its caller, etc. The
3710argument is <b>required</b> to be a constant integer value.
3711</p>
3712
3713<h5>Semantics:</h5>
3714
3715<p>
3716The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3717the return address of the specified call frame, or zero if it cannot be
3718identified. The value returned by this intrinsic is likely to be incorrect or 0
3719for arguments other than zero, so it should only be used for debugging purposes.
3720</p>
3721
3722<p>
3723Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3724aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3725source-language caller.
3726</p>
3727</div>
3728
3729
3730<!-- _______________________________________________________________________ -->
3731<div class="doc_subsubsection">
3732 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
3733</div>
3734
3735<div class="doc_text">
3736
3737<h5>Syntax:</h5>
3738<pre>
Chris Lattnerfcf39d42006-01-13 01:20:27 +0000[diff] [blame]3739 declare sbyte *%llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3740</pre>
3741
3742<h5>Overview:</h5>
3743
3744<p>
Chris Lattner32b5d712006-10-15 20:05:59 +0000[diff] [blame]3745The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3746target-specific frame pointer value for the specified stack frame.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3747</p>
3748
3749<h5>Arguments:</h5>
3750
3751<p>
3752The argument to this intrinsic indicates which function to return the frame
3753pointer for. Zero indicates the calling function, one indicates its caller,
3754etc. The argument is <b>required</b> to be a constant integer value.
3755</p>
3756
3757<h5>Semantics:</h5>
3758
3759<p>
3760The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3761the frame address of the specified call frame, or zero if it cannot be
3762identified. The value returned by this intrinsic is likely to be incorrect or 0
3763for arguments other than zero, so it should only be used for debugging purposes.
3764</p>
3765
3766<p>
3767Note that calling this intrinsic does not prevent function inlining or other
Chris Lattnerb40bb382005-03-07 20:30:51 +0000[diff] [blame]3768aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3769source-language caller.
3770</p>
3771</div>
3772
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3773<!-- _______________________________________________________________________ -->
3774<div class="doc_subsubsection">
Chris Lattner57e1f392006-01-13 02:03:13 +0000[diff] [blame]3775 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
3776</div>
3777
3778<div class="doc_text">
3779
3780<h5>Syntax:</h5>
3781<pre>
3782 declare sbyte *%llvm.stacksave()
3783</pre>
3784
3785<h5>Overview:</h5>
3786
3787<p>
3788The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
3789the function stack, for use with <a href="#i_stackrestore">
3790<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3791features like scoped automatic variable sized arrays in C99.
3792</p>
3793
3794<h5>Semantics:</h5>
3795
3796<p>
3797This intrinsic returns a opaque pointer value that can be passed to <a
3798href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
3799<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
3800<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
3801state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
3802practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
3803that were allocated after the <tt>llvm.stacksave</tt> was executed.
3804</p>
3805
3806</div>
3807
3808<!-- _______________________________________________________________________ -->
3809<div class="doc_subsubsection">
3810 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
3811</div>
3812
3813<div class="doc_text">
3814
3815<h5>Syntax:</h5>
3816<pre>
3817 declare void %llvm.stackrestore(sbyte* %ptr)
3818</pre>
3819
3820<h5>Overview:</h5>
3821
3822<p>
3823The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
3824the function stack to the state it was in when the corresponding <a
3825href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
3826useful for implementing language features like scoped automatic variable sized
3827arrays in C99.
3828</p>
3829
3830<h5>Semantics:</h5>
3831
3832<p>
3833See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
3834</p>
3835
3836</div>
3837
3838
3839<!-- _______________________________________________________________________ -->
3840<div class="doc_subsubsection">
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3841 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
3842</div>
3843
3844<div class="doc_text">
3845
3846<h5>Syntax:</h5>
3847<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3848 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
3849 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3850</pre>
3851
3852<h5>Overview:</h5>
3853
3854
3855<p>
3856The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3857a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
3858no
3859effect on the behavior of the program but can change its performance
Chris Lattner2a615362005-02-28 19:47:14 +0000[diff] [blame]3860characteristics.
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3861</p>
3862
3863<h5>Arguments:</h5>
3864
3865<p>
3866<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
3867determining if the fetch should be for a read (0) or write (1), and
3868<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattneraeffb4a2005-03-07 20:31:38 +0000[diff] [blame]3869locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattner9a9d7ac2005-02-28 19:24:19 +0000[diff] [blame]3870<tt>locality</tt> arguments must be constant integers.
3871</p>
3872
3873<h5>Semantics:</h5>
3874
3875<p>
3876This intrinsic does not modify the behavior of the program. In particular,
3877prefetches cannot trap and do not produce a value. On targets that support this
3878intrinsic, the prefetch can provide hints to the processor cache for better
3879performance.
3880</p>
3881
3882</div>
3883
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3884<!-- _______________________________________________________________________ -->
3885<div class="doc_subsubsection">
3886 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
3887</div>
3888
3889<div class="doc_text">
3890
3891<h5>Syntax:</h5>
3892<pre>
Reid Spencera8d451e2005-04-26 20:50:44 +0000[diff] [blame]3893 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3894</pre>
3895
3896<h5>Overview:</h5>
3897
3898
3899<p>
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3900The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
3901(PC) in a region of
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3902code to simulators and other tools. The method is target specific, but it is
3903expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohen25d4f7e2005-11-11 02:15:27 +0000[diff] [blame]3904The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnerd07c3f42005-11-15 06:07:55 +0000[diff] [blame]3905after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb3e7afd2006-03-24 07:16:10 +0000[diff] [blame]3906optimizations. The intended use is to be inserted after optimizations to allow
John Criswellfc6b8952005-05-16 16:17:45 +0000[diff] [blame]3907correlations of simulation runs.
Andrew Lenharth7f4ec3b2005-03-28 20:05:49 +0000[diff] [blame]3908</p>
3909
3910<h5>Arguments:</h5>
3911
3912<p>
3913<tt>id</tt> is a numerical id identifying the marker.
3914</p>
3915
3916<h5>Semantics:</h5>
3917
3918<p>
3919This intrinsic does not modify the behavior of the program. Backends that do not
3920support this intrinisic may ignore it.
3921</p>
3922
3923</div>
3924
Andrew Lenharth51b8d542005-11-11 16:47:30 +0000[diff] [blame]3925<!-- _______________________________________________________________________ -->
3926<div class="doc_subsubsection">
3927 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
3928</div>
3929
3930<div class="doc_text">
3931
3932<h5>Syntax:</h5>
3933<pre>
3934 declare ulong %llvm.readcyclecounter( )
3935</pre>
3936
3937<h5>Overview:</h5>
3938
3939
3940<p>
3941The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
3942counter register (or similar low latency, high accuracy clocks) on those targets
3943that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
3944As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
3945should only be used for small timings.
3946</p>
3947
3948<h5>Semantics:</h5>
3949
3950<p>
3951When directly supported, reading the cycle counter should not modify any memory.
3952Implementations are allowed to either return a application specific value or a
3953system wide value. On backends without support, this is lowered to a constant 0.
3954</p>
3955
3956</div>
3957
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3958<!-- ======================================================================= -->
3959<div class="doc_subsection">
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3960 <a name="int_libc">Standard C Library Intrinsics</a>
3961</div>
3962
3963<div class="doc_text">
3964<p>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]3965LLVM provides intrinsics for a few important standard C library functions.
3966These intrinsics allow source-language front-ends to pass information about the
3967alignment of the pointer arguments to the code generator, providing opportunity
3968for more efficient code generation.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3969</p>
3970
3971</div>
3972
3973<!-- _______________________________________________________________________ -->
3974<div class="doc_subsubsection">
3975 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
3976</div>
3977
3978<div class="doc_text">
3979
3980<h5>Syntax:</h5>
3981<pre>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]3982 declare void %llvm.memcpy.i32(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3983 uint &lt;len&gt;, uint &lt;align&gt;)
3984 declare void %llvm.memcpy.i64(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3985 ulong &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3986</pre>
3987
3988<h5>Overview:</h5>
3989
3990<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]3991The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3992location to the destination location.
3993</p>
3994
3995<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]3996Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
3997intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]3998</p>
3999
4000<h5>Arguments:</h5>
4001
4002<p>
4003The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4004the source. The third argument is an integer argument
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4005specifying the number of bytes to copy, and the fourth argument is the alignment
4006of the source and destination locations.
4007</p>
4008
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4009<p>
4010If 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]4011the caller guarantees that both the source and destination pointers are aligned
4012to that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4013</p>
4014
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4015<h5>Semantics:</h5>
4016
4017<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4018The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner33aec9e2004-02-12 17:01:32 +0000[diff] [blame]4019location to the destination location, which are not allowed to overlap. It
4020copies "len" bytes of memory over. If the argument is known to be aligned to
4021some boundary, this can be specified as the fourth argument, otherwise it should
4022be set to 0 or 1.
4023</p>
4024</div>
4025
4026
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4027<!-- _______________________________________________________________________ -->
4028<div class="doc_subsubsection">
4029 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4030</div>
4031
4032<div class="doc_text">
4033
4034<h5>Syntax:</h5>
4035<pre>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4036 declare void %llvm.memmove.i32(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
4037 uint &lt;len&gt;, uint &lt;align&gt;)
4038 declare void %llvm.memmove.i64(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
4039 ulong &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4040</pre>
4041
4042<h5>Overview:</h5>
4043
4044<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4045The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4046location to the destination location. It is similar to the
4047'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4048</p>
4049
4050<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4051Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4052intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4053</p>
4054
4055<h5>Arguments:</h5>
4056
4057<p>
4058The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4059the source. The third argument is an integer argument
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4060specifying the number of bytes to copy, and the fourth argument is the alignment
4061of the source and destination locations.
4062</p>
4063
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4064<p>
4065If 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]4066the caller guarantees that the source and destination pointers are aligned to
4067that boundary.
Chris Lattner3301ced2004-02-12 21:18:15 +0000[diff] [blame]4068</p>
4069
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4070<h5>Semantics:</h5>
4071
4072<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4073The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattner0eb51b42004-02-12 18:10:10 +0000[diff] [blame]4074location to the destination location, which may overlap. It
4075copies "len" bytes of memory over. If the argument is known to be aligned to
4076some boundary, this can be specified as the fourth argument, otherwise it should
4077be set to 0 or 1.
4078</p>
4079</div>
4080
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4081
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4082<!-- _______________________________________________________________________ -->
4083<div class="doc_subsubsection">
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4084 <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4085</div>
4086
4087<div class="doc_text">
4088
4089<h5>Syntax:</h5>
4090<pre>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4091 declare void %llvm.memset.i32(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
4092 uint &lt;len&gt;, uint &lt;align&gt;)
4093 declare void %llvm.memset.i64(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
4094 ulong &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4095</pre>
4096
4097<h5>Overview:</h5>
4098
4099<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4100The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4101byte value.
4102</p>
4103
4104<p>
4105Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4106does not return a value, and takes an extra alignment argument.
4107</p>
4108
4109<h5>Arguments:</h5>
4110
4111<p>
4112The first argument is a pointer to the destination to fill, the second is the
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4113byte value to fill it with, the third argument is an integer
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4114argument specifying the number of bytes to fill, and the fourth argument is the
4115known alignment of destination location.
4116</p>
4117
4118<p>
4119If 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]4120the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4121</p>
4122
4123<h5>Semantics:</h5>
4124
4125<p>
Chris Lattner5b310c32006-03-03 00:07:20 +0000[diff] [blame]4126The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4127the
Chris Lattner10610642004-02-14 04:08:35 +0000[diff] [blame]4128destination location. If the argument is known to be aligned to some boundary,
4129this can be specified as the fourth argument, otherwise it should be set to 0 or
41301.
4131</p>
4132</div>
4133
4134
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4135<!-- _______________________________________________________________________ -->
4136<div class="doc_subsubsection">
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4137 <a name="i_isunordered">'<tt>llvm.isunordered.*</tt>' Intrinsic</a>
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]4138</div>
4139
4140<div class="doc_text">
4141
4142<h5>Syntax:</h5>
4143<pre>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4144 declare bool %llvm.isunordered.f32(float Val1, float Val2)
4145 declare bool %llvm.isunordered.f64(double Val1, double Val2)
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]4146</pre>
4147
4148<h5>Overview:</h5>
4149
4150<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4151The '<tt>llvm.isunordered</tt>' intrinsics return true if either or both of the
Alkis Evlogimenos26bbe932004-06-13 01:16:15 +0000[diff] [blame]4152specified floating point values is a NAN.
4153</p>
4154
4155<h5>Arguments:</h5>
4156
4157<p>
4158The arguments are floating point numbers of the same type.
4159</p>
4160
4161<h5>Semantics:</h5>
4162
4163<p>
4164If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
4165false.
4166</p>
4167</div>
4168
4169
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4170<!-- _______________________________________________________________________ -->
4171<div class="doc_subsubsection">
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4172 <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4173</div>
4174
4175<div class="doc_text">
4176
4177<h5>Syntax:</h5>
4178<pre>
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4179 declare float %llvm.sqrt.f32(float %Val)
4180 declare double %llvm.sqrt.f64(double %Val)
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4181</pre>
4182
4183<h5>Overview:</h5>
4184
4185<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4186The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattnera4d74142005-07-21 01:29:16 +0000[diff] [blame]4187returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4188<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4189negative numbers (which allows for better optimization).
4190</p>
4191
4192<h5>Arguments:</h5>
4193
4194<p>
4195The argument and return value are floating point numbers of the same type.
4196</p>
4197
4198<h5>Semantics:</h5>
4199
4200<p>
4201This function returns the sqrt of the specified operand if it is a positive
4202floating point number.
4203</p>
4204</div>
4205
Chris Lattnerf4d252d2006-09-08 06:34:02 +0000[diff] [blame]4206<!-- _______________________________________________________________________ -->
4207<div class="doc_subsubsection">
4208 <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4209</div>
4210
4211<div class="doc_text">
4212
4213<h5>Syntax:</h5>
4214<pre>
4215 declare float %llvm.powi.f32(float %Val, int %power)
4216 declare double %llvm.powi.f64(double %Val, int %power)
4217</pre>
4218
4219<h5>Overview:</h5>
4220
4221<p>
4222The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4223specified (positive or negative) power. The order of evaluation of
4224multiplications is not defined.
4225</p>
4226
4227<h5>Arguments:</h5>
4228
4229<p>
4230The second argument is an integer power, and the first is a value to raise to
4231that power.
4232</p>
4233
4234<h5>Semantics:</h5>
4235
4236<p>
4237This function returns the first value raised to the second power with an
4238unspecified sequence of rounding operations.</p>
4239</div>
4240
4241
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4242<!-- ======================================================================= -->
4243<div class="doc_subsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4244 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4245</div>
4246
4247<div class="doc_text">
4248<p>
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4249LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4250These allow efficient code generation for some algorithms.
4251</p>
4252
4253</div>
4254
4255<!-- _______________________________________________________________________ -->
4256<div class="doc_subsubsection">
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4257 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4258</div>
4259
4260<div class="doc_text">
4261
4262<h5>Syntax:</h5>
4263<pre>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4264 declare ushort %llvm.bswap.i16(ushort &lt;id&gt;)
4265 declare uint %llvm.bswap.i32(uint &lt;id&gt;)
4266 declare ulong %llvm.bswap.i64(ulong &lt;id&gt;)
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4267</pre>
4268
4269<h5>Overview:</h5>
4270
4271<p>
4272The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
427364 bit quantity. These are useful for performing operations on data that is not
4274in the target's native byte order.
4275</p>
4276
4277<h5>Semantics:</h5>
4278
4279<p>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4280The <tt>llvm.bswap.16</tt> intrinsic returns a ushort value that has the high and low
4281byte of the input ushort swapped. Similarly, the <tt>llvm.bswap.i32</tt> intrinsic
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4282returns a uint value that has the four bytes of the input uint swapped, so that
4283if the input bytes are numbered 0, 1, 2, 3 then the returned uint will have its
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4284bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt> intrinsic extends this concept
Nate Begeman7e36c472006-01-13 23:26:38 +0000[diff] [blame]4285to 64 bits.
4286</p>
4287
4288</div>
4289
4290<!-- _______________________________________________________________________ -->
4291<div class="doc_subsubsection">
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4292 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4293</div>
4294
4295<div class="doc_text">
4296
4297<h5>Syntax:</h5>
4298<pre>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4299 declare ubyte %llvm.ctpop.i8 (ubyte &lt;src&gt;)
4300 declare ushort %llvm.ctpop.i16(ushort &lt;src&gt;)
4301 declare uint %llvm.ctpop.i32(uint &lt;src&gt;)
4302 declare ulong %llvm.ctpop.i64(ulong &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4303</pre>
4304
4305<h5>Overview:</h5>
4306
4307<p>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4308The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4309value.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4310</p>
4311
4312<h5>Arguments:</h5>
4313
4314<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4315The only argument is the value to be counted. The argument may be of any
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4316unsigned integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4317</p>
4318
4319<h5>Semantics:</h5>
4320
4321<p>
4322The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4323</p>
4324</div>
4325
4326<!-- _______________________________________________________________________ -->
4327<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4328 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4329</div>
4330
4331<div class="doc_text">
4332
4333<h5>Syntax:</h5>
4334<pre>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4335 declare ubyte %llvm.ctlz.i8 (ubyte &lt;src&gt;)
4336 declare ushort %llvm.ctlz.i16(ushort &lt;src&gt;)
4337 declare uint %llvm.ctlz.i32(uint &lt;src&gt;)
4338 declare ulong %llvm.ctlz.i64(ulong &lt;src&gt;)
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4339</pre>
4340
4341<h5>Overview:</h5>
4342
4343<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4344The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4345leading zeros in a variable.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4346</p>
4347
4348<h5>Arguments:</h5>
4349
4350<p>
Chris Lattnercfe6b372005-05-07 01:46:40 +0000[diff] [blame]4351The only argument is the value to be counted. The argument may be of any
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4352unsigned integer type. The return type must match the argument type.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4353</p>
4354
4355<h5>Semantics:</h5>
4356
4357<p>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4358The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4359in a variable. If the src == 0 then the result is the size in bits of the type
Chris Lattner99d3c272006-04-21 21:37:40 +0000[diff] [blame]4360of src. For example, <tt>llvm.ctlz(int 2) = 30</tt>.
Andrew Lenharthec370fd2005-05-03 18:01:48 +0000[diff] [blame]4361</p>
4362</div>
Chris Lattner32006282004-06-11 02:28:03 +0000[diff] [blame]4363
4364
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4365
4366<!-- _______________________________________________________________________ -->
4367<div class="doc_subsubsection">
Chris Lattner8a886be2006-01-16 22:34:14 +0000[diff] [blame]4368 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4369</div>
4370
4371<div class="doc_text">
4372
4373<h5>Syntax:</h5>
4374<pre>
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4375 declare ubyte %llvm.cttz.i8 (ubyte &lt;src&gt;)
4376 declare ushort %llvm.cttz.i16(ushort &lt;src&gt;)
4377 declare uint %llvm.cttz.i32(uint &lt;src&gt;)
4378 declare ulong %llvm.cttz.i64(ulong &lt;src&gt;)
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4379</pre>
4380
4381<h5>Overview:</h5>
4382
4383<p>
Reid Spencer0b118202006-01-16 21:12:35 +0000[diff] [blame]4384The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4385trailing zeros.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4386</p>
4387
4388<h5>Arguments:</h5>
4389
4390<p>
4391The only argument is the value to be counted. The argument may be of any
Chris Lattnerec6cb612006-01-16 22:38:59 +0000[diff] [blame]4392unsigned integer type. The return type must match the argument type.
Chris Lattnereff29ab2005-05-15 19:39:26 +0000[diff] [blame]4393</p>
4394
4395<h5>Semantics:</h5>
4396
4397<p>
4398The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4399in a variable. If the src == 0 then the result is the size in bits of the type
4400of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4401</p>
4402</div>
4403
Chris Lattner8ff75902004-01-06 05:31:32 +0000[diff] [blame]4404<!-- ======================================================================= -->
4405<div class="doc_subsection">
4406 <a name="int_debugger">Debugger Intrinsics</a>
4407</div>
4408
4409<div class="doc_text">
4410<p>
4411The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4412are described in the <a
4413href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4414Debugging</a> document.
4415</p>
4416</div>
4417
4418
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4419<!-- *********************************************************************** -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]4420<hr>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4421<address>
4422 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4423 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
4424 <a href="http://validator.w3.org/check/referer"><img
4425 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4426
4427 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]4428 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmandaa4cb02004-03-01 17:47:27 +0000[diff] [blame]4429 Last modified: $Date$
4430</address>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]4431</body>
4432</html>