Gitiles
Code Review Sign In
gerrit-public.fairphone.software / toolchain / llvm-project / 88190562e6269c2e133677c9620b46be1ce45c7b / . / llvm / docs / LangRef.html
blob: d5abdce7af00162a624a0928e376f32d84a37d94 [file] [log] [blame]
Misha Brukmanc501f552004-03-01 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 Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3<html>
4<head>
5 <title>LLVM Assembly Language Reference Manual</title>
Reid Spencercb84e432004-08-26 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 Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]10 <link rel="stylesheet" href="llvm.css" type="text/css">
11</head>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman76307852003-11-08 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 Lattner6af02f32004-12-09 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 Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]25 <li><a href="#globalvars">Global Variables</a></li>
26 <li><a href="#functionstructure">Function Structure</a></li>
27 </ol>
28 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]29 <li><a href="#typesystem">Type System</a>
30 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]31 <li><a href="#t_primitive">Primitive Types</a>
32 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]33 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]34 </ol>
35 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]36 <li><a href="#t_derived">Derived Types</a>
37 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]38 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]39 <li><a href="#t_function">Function Type</a></li>
40 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]41 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]42 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]43 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]44 </ol>
45 </li>
46 </ol>
47 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]48 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]49 <ol>
50 <li><a href="#simpleconstants">Simple Constants</a>
51 <li><a href="#aggregateconstants">Aggregate Constants</a>
52 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
53 <li><a href="#undefvalues">Undefined Values</a>
54 <li><a href="#constantexprs">Constant Expressions</a>
55 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]56 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]57 <li><a href="#instref">Instruction Reference</a>
58 <ol>
59 <li><a href="#terminators">Terminator Instructions</a>
60 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]61 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
62 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]63 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
64 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]65 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]66 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]67 </ol>
68 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]69 <li><a href="#binaryops">Binary Operations</a>
70 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]71 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
72 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
73 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
74 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
75 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]76 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]77 </ol>
78 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]79 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
80 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]81 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]82 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]83 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
84 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
85 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]86 </ol>
87 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]88 <li><a href="#memoryops">Memory Access Operations</a>
89 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]90 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
91 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
92 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
93 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
94 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
95 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
96 </ol>
97 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]98 <li><a href="#otherops">Other Operations</a>
99 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]100 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]101 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]102 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]103 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]104 <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]105 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]106 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]107 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]108 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]109 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]110 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]111 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]112 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
113 <ol>
114 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
115 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
116 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
117 </ol>
118 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]119 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
120 <ol>
121 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
122 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
123 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
124 </ol>
125 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]126 <li><a href="#int_codegen">Code Generator Intrinsics</a>
127 <ol>
128 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
129 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]130 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]131 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]132 </ol>
133 </li>
134 <li><a href="#int_os">Operating System Intrinsics</a>
135 <ol>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]136 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
137 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]138 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
139 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]140 </ol>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]141 <li><a href="#int_libc">Standard C Library Intrinsics</a>
142 <ol>
143 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]144 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]145 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos9d740622004-06-12 19:19:14 +0000[diff] [blame]146 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]147 </ol>
148 </li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]149 <li><a href="#int_count">Bit counting Intrinsics</a>
150 <ol>
151 <li><a href="#int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]152 <li><a href="#int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic </a></li>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]153 <li><a href="#int_cttz">'<tt>llvm.cttz</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]154 </ol>
155 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]156 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]157 </ol>
158 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]159</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]160
161<div class="doc_author">
162 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
163 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]164</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]165
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]166<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]167<div class="doc_section"> <a name="abstract">Abstract </a></div>
168<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]169
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]170<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]171<p>This document is a reference manual for the LLVM assembly language.
172LLVM is an SSA based representation that provides type safety,
173low-level operations, flexibility, and the capability of representing
174'all' high-level languages cleanly. It is the common code
175representation used throughout all phases of the LLVM compilation
176strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]177</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]178
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]179<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]180<div class="doc_section"> <a name="introduction">Introduction</a> </div>
181<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]182
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]183<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]184
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]185<p>The LLVM code representation is designed to be used in three
186different forms: as an in-memory compiler IR, as an on-disk bytecode
187representation (suitable for fast loading by a Just-In-Time compiler),
188and as a human readable assembly language representation. This allows
189LLVM to provide a powerful intermediate representation for efficient
190compiler transformations and analysis, while providing a natural means
191to debug and visualize the transformations. The three different forms
192of LLVM are all equivalent. This document describes the human readable
193representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]194
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]195<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]196while being expressive, typed, and extensible at the same time. It
197aims to be a "universal IR" of sorts, by being at a low enough level
198that high-level ideas may be cleanly mapped to it (similar to how
199microprocessors are "universal IR's", allowing many source languages to
200be mapped to them). By providing type information, LLVM can be used as
201the target of optimizations: for example, through pointer analysis, it
202can be proven that a C automatic variable is never accessed outside of
203the current function... allowing it to be promoted to a simple SSA
204value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]205
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]206</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]207
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]208<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]209<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]210
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]211<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]212
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]213<p>It is important to note that this document describes 'well formed'
214LLVM assembly language. There is a difference between what the parser
215accepts and what is considered 'well formed'. For example, the
216following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]217
218<pre>
219 %x = <a href="#i_add">add</a> int 1, %x
220</pre>
221
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]222<p>...because the definition of <tt>%x</tt> does not dominate all of
223its uses. The LLVM infrastructure provides a verification pass that may
224be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]225automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]226the optimizer before it outputs bytecode. The violations pointed out
227by the verifier pass indicate bugs in transformation passes or input to
228the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]229
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]230<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]231
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]232<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]233<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]234<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]235
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]236<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]237
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]238<p>LLVM uses three different forms of identifiers, for different
239purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]240
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]241<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]242 <li>Named values are represented as a string of characters with a '%' prefix.
243 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
244 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
245 Identifiers which require other characters in their names can be surrounded
246 with quotes. In this way, anything except a <tt>"</tt> character can be used
247 in a name.</li>
248
249 <li>Unnamed values are represented as an unsigned numeric value with a '%'
250 prefix. For example, %12, %2, %44.</li>
251
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]252 <li>Constants, which are described in a <a href="#constants">section about
253 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]254</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]255
256<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
257don't need to worry about name clashes with reserved words, and the set of
258reserved words may be expanded in the future without penalty. Additionally,
259unnamed identifiers allow a compiler to quickly come up with a temporary
260variable without having to avoid symbol table conflicts.</p>
261
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]262<p>Reserved words in LLVM are very similar to reserved words in other
263languages. There are keywords for different opcodes ('<tt><a
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]264href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
265href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
266href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
267and others. These reserved words cannot conflict with variable names, because
268none of them start with a '%' character.</p>
269
270<p>Here is an example of LLVM code to multiply the integer variable
271'<tt>%X</tt>' by 8:</p>
272
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]273<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]274
275<pre>
276 %result = <a href="#i_mul">mul</a> uint %X, 8
277</pre>
278
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]279<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]280
281<pre>
282 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
283</pre>
284
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]285<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]286
287<pre>
288 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
289 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
290 %result = <a href="#i_add">add</a> uint %1, %1
291</pre>
292
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]293<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
294important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]295
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]296<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]297
298 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
299 line.</li>
300
301 <li>Unnamed temporaries are created when the result of a computation is not
302 assigned to a named value.</li>
303
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]304 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]305
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]306</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]307
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]308<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]309demonstrating instructions, we will follow an instruction with a comment that
310defines the type and name of value produced. Comments are shown in italic
311text.</p>
312
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]313</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]314
315<!-- *********************************************************************** -->
316<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
317<!-- *********************************************************************** -->
318
319<!-- ======================================================================= -->
320<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
321</div>
322
323<div class="doc_text">
324
325<p>LLVM programs are composed of "Module"s, each of which is a
326translation unit of the input programs. Each module consists of
327functions, global variables, and symbol table entries. Modules may be
328combined together with the LLVM linker, which merges function (and
329global variable) definitions, resolves forward declarations, and merges
330symbol table entries. Here is an example of the "hello world" module:</p>
331
332<pre><i>; Declare the string constant as a global constant...</i>
333<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
334 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
335
336<i>; External declaration of the puts function</i>
337<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
338
339<i>; Definition of main function</i>
340int %main() { <i>; int()* </i>
341 <i>; Convert [13x sbyte]* to sbyte *...</i>
342 %cast210 = <a
343 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
344
345 <i>; Call puts function to write out the string to stdout...</i>
346 <a
347 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
348 <a
349 href="#i_ret">ret</a> int 0<br>}<br></pre>
350
351<p>This example is made up of a <a href="#globalvars">global variable</a>
352named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
353function, and a <a href="#functionstructure">function definition</a>
354for "<tt>main</tt>".</p>
355
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]356<p>In general, a module is made up of a list of global values,
357where both functions and global variables are global values. Global values are
358represented by a pointer to a memory location (in this case, a pointer to an
359array of char, and a pointer to a function), and have one of the following <a
360href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]361
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]362</div>
363
364<!-- ======================================================================= -->
365<div class="doc_subsection">
366 <a name="linkage">Linkage Types</a>
367</div>
368
369<div class="doc_text">
370
371<p>
372All Global Variables and Functions have one of the following types of linkage:
373</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]374
375<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]376
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]377 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]378
379 <dd>Global values with internal linkage are only directly accessible by
380 objects in the current module. In particular, linking code into a module with
381 an internal global value may cause the internal to be renamed as necessary to
382 avoid collisions. Because the symbol is internal to the module, all
383 references can be updated. This corresponds to the notion of the
384 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]385 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]386
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]387 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]388
389 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
390 the twist that linking together two modules defining the same
391 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
392 is typically used to implement inline functions. Unreferenced
393 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]394 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]395
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]396 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]397
398 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
399 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
400 used to implement constructs in C such as "<tt>int X;</tt>" at global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]401 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]402
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]403 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]404
405 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
406 pointer to array type. When two global variables with appending linkage are
407 linked together, the two global arrays are appended together. This is the
408 LLVM, typesafe, equivalent of having the system linker append together
409 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]410 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]411
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]412 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]413
414 <dd>If none of the above identifiers are used, the global is externally
415 visible, meaning that it participates in linkage and can be used to resolve
416 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]417 </dd>
418</dl>
419
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]420<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
421variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
422variable and was linked with this one, one of the two would be renamed,
423preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
424external (i.e., lacking any linkage declarations), they are accessible
425outside of the current module. It is illegal for a function <i>declaration</i>
426to have any linkage type other than "externally visible".</a></p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]427
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]428</div>
429
430<!-- ======================================================================= -->
431<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]432 <a name="callingconv">Calling Conventions</a>
433</div>
434
435<div class="doc_text">
436
437<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
438and <a href="#i_invoke">invokes</a> can all have an optional calling convention
439specified for the call. The calling convention of any pair of dynamic
440caller/callee must match, or the behavior of the program is undefined. The
441following calling conventions are supported by LLVM, and more may be added in
442the future:</p>
443
444<dl>
445 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
446
447 <dd>This calling convention (the default if no other calling convention is
448 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]449 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]450 prototype and implemented declaration of the function (as does normal C).
451 </dd>
452
453 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
454
455 <dd>This calling convention attempts to make calls as fast as possible
456 (e.g. by passing things in registers). This calling convention allows the
457 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]458 without having to conform to an externally specified ABI. Implementations of
459 this convention should allow arbitrary tail call optimization to be supported.
460 This calling convention does not support varargs and requires the prototype of
461 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]462 </dd>
463
464 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
465
466 <dd>This calling convention attempts to make code in the caller as efficient
467 as possible under the assumption that the call is not commonly executed. As
468 such, these calls often preserve all registers so that the call does not break
469 any live ranges in the caller side. This calling convention does not support
470 varargs and requires the prototype of all callees to exactly match the
471 prototype of the function definition.
472 </dd>
473
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]474 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]475
476 <dd>Any calling convention may be specified by number, allowing
477 target-specific calling conventions to be used. Target specific calling
478 conventions start at 64.
479 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]480</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]481
482<p>More calling conventions can be added/defined on an as-needed basis, to
483support pascal conventions or any other well-known target-independent
484convention.</p>
485
486</div>
487
488<!-- ======================================================================= -->
489<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]490 <a name="globalvars">Global Variables</a>
491</div>
492
493<div class="doc_text">
494
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]495<p>Global variables define regions of memory allocated at compilation time
496instead of run-time. Global variables may optionally be initialized. A
497variable may be defined as a global "constant", which indicates that the
498contents of the variable will <b>never</b> be modified (enabling better
499optimization, allowing the global data to be placed in the read-only section of
500an executable, etc). Note that variables that need runtime initialization
501cannot be marked "constant", as there is a store to the variable.</p>
502
503<p>
504LLVM explicitly allows <em>declarations</em> of global variables to be marked
505constant, even if the final definition of the global is not. This capability
506can be used to enable slightly better optimization of the program, but requires
507the language definition to guarantee that optimizations based on the
508'constantness' are valid for the translation units that do not include the
509definition.
510</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]511
512<p>As SSA values, global variables define pointer values that are in
513scope (i.e. they dominate) all basic blocks in the program. Global
514variables always define a pointer to their "content" type because they
515describe a region of memory, and all memory objects in LLVM are
516accessed through pointers.</p>
517
518</div>
519
520
521<!-- ======================================================================= -->
522<div class="doc_subsection">
523 <a name="functionstructure">Functions</a>
524</div>
525
526<div class="doc_text">
527
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]528<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
529type</a>, an optional <a href="#callingconv">calling convention</a>, a return
530type, a function name, a (possibly empty) argument list, an opening curly brace,
531a list of basic blocks, and a closing curly brace. LLVM function declarations
532are defined with the "<tt>declare</tt>" keyword, an optional <a
533href="#callingconv">calling convention</a>, a return type, a function name, and
534a possibly empty list of arguments.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]535
536<p>A function definition contains a list of basic blocks, forming the CFG for
537the function. Each basic block may optionally start with a label (giving the
538basic block a symbol table entry), contains a list of instructions, and ends
539with a <a href="#terminators">terminator</a> instruction (such as a branch or
540function return).</p>
541
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]542<p>The first basic block in a program is special in two ways: it is immediately
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]543executed on entrance to the function, and it is not allowed to have predecessor
544basic blocks (i.e. there can not be any branches to the entry block of a
545function). Because the block can have no predecessors, it also cannot have any
546<a href="#i_phi">PHI nodes</a>.</p>
547
548<p>LLVM functions are identified by their name and type signature. Hence, two
549functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]550considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]551appropriately.</p>
552
553</div>
554
555
556
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]557<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]558<div class="doc_section"> <a name="typesystem">Type System</a> </div>
559<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]560
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]561<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]562
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]563<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]564intermediate representation. Being typed enables a number of
565optimizations to be performed on the IR directly, without having to do
566extra analyses on the side before the transformation. A strong type
567system makes it easier to read the generated code and enables novel
568analyses and transformations that are not feasible to perform on normal
569three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]570
571</div>
572
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]573<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]574<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]575<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]576<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]577system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]578
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]579<table class="layout">
580 <tr class="layout">
581 <td class="left">
582 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]583 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]584 <tr><th>Type</th><th>Description</th></tr>
585 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]586 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
587 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
588 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
589 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
590 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]591 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]592 </tbody>
593 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]594 </td>
595 <td class="right">
596 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]597 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]598 <tr><th>Type</th><th>Description</th></tr>
599 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]600 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
601 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
602 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
603 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
604 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]605 </tbody>
606 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]607 </td>
608 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]609</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]610</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]611
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]612<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]613<div class="doc_subsubsection"> <a name="t_classifications">Type
614Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]615<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]616<p>These different primitive types fall into a few useful
617classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]618
619<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]620 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]621 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]622 <tr>
623 <td><a name="t_signed">signed</a></td>
624 <td><tt>sbyte, short, int, long, float, double</tt></td>
625 </tr>
626 <tr>
627 <td><a name="t_unsigned">unsigned</a></td>
628 <td><tt>ubyte, ushort, uint, ulong</tt></td>
629 </tr>
630 <tr>
631 <td><a name="t_integer">integer</a></td>
632 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
633 </tr>
634 <tr>
635 <td><a name="t_integral">integral</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]636 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
637 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]638 </tr>
639 <tr>
640 <td><a name="t_floating">floating point</a></td>
641 <td><tt>float, double</tt></td>
642 </tr>
643 <tr>
644 <td><a name="t_firstclass">first class</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]645 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
646 float, double, <a href="#t_pointer">pointer</a>,
647 <a href="#t_packed">packed</a></tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]648 </tr>
649 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]650</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]651
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]652<p>The <a href="#t_firstclass">first class</a> types are perhaps the
653most important. Values of these types are the only ones which can be
654produced by instructions, passed as arguments, or used as operands to
655instructions. This means that all structures and arrays must be
656manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]657</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]658
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]659<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]660<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]661
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]662<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]663
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]664<p>The real power in LLVM comes from the derived types in the system.
665This is what allows a programmer to represent arrays, functions,
666pointers, and other useful types. Note that these derived types may be
667recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]668
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]669</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]670
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]671<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]672<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]673
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]674<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]675
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]676<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]677
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]678<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]679sequentially in memory. The array type requires a size (number of
680elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]681
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]682<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]683
684<pre>
685 [&lt;# elements&gt; x &lt;elementtype&gt;]
686</pre>
687
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]688<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]689be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]690
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]691<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]692<table class="layout">
693 <tr class="layout">
694 <td class="left">
695 <tt>[40 x int ]</tt><br/>
696 <tt>[41 x int ]</tt><br/>
697 <tt>[40 x uint]</tt><br/>
698 </td>
699 <td class="left">
700 Array of 40 integer values.<br/>
701 Array of 41 integer values.<br/>
702 Array of 40 unsigned integer values.<br/>
703 </td>
704 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]705</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]706<p>Here are some examples of multidimensional arrays:</p>
707<table class="layout">
708 <tr class="layout">
709 <td class="left">
710 <tt>[3 x [4 x int]]</tt><br/>
711 <tt>[12 x [10 x float]]</tt><br/>
712 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
713 </td>
714 <td class="left">
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]715 3x4 array of integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]716 12x10 array of single precision floating point values.<br/>
717 2x3x4 array of unsigned integer values.<br/>
718 </td>
719 </tr>
720</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]721</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]722
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]723<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]724<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]725<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]726<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]727<p>The function type can be thought of as a function signature. It
728consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]729Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]730(which are structures of pointers to functions), for indirect function
731calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]732<p>
733The return type of a function type cannot be an aggregate type.
734</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]735<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]736<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]737<p>Where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
738specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]739which indicates that the function takes a variable number of arguments.
740Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]741 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]742<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]743<table class="layout">
744 <tr class="layout">
745 <td class="left">
746 <tt>int (int)</tt> <br/>
747 <tt>float (int, int *) *</tt><br/>
748 <tt>int (sbyte *, ...)</tt><br/>
749 </td>
750 <td class="left">
751 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
752 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]753 <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]754 returning <tt>float</tt>.<br/>
755 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
756 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
757 the signature for <tt>printf</tt> in LLVM.<br/>
758 </td>
759 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]760</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]761
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]762</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]763<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]764<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]765<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]766<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]767<p>The structure type is used to represent a collection of data members
768together in memory. The packing of the field types is defined to match
769the ABI of the underlying processor. The elements of a structure may
770be any type that has a size.</p>
771<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
772and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
773field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
774instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]775<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]776<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]777<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]778<table class="layout">
779 <tr class="layout">
780 <td class="left">
781 <tt>{ int, int, int }</tt><br/>
782 <tt>{ float, int (int) * }</tt><br/>
783 </td>
784 <td class="left">
785 a triple of three <tt>int</tt> values<br/>
786 A pair, where the first element is a <tt>float</tt> and the second element
787 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
788 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
789 </td>
790 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]791</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]792</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]793
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]794<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]795<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]796<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]797<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]798<p>As in many languages, the pointer type represents a pointer or
799reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]800<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]801<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]802<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]803<table class="layout">
804 <tr class="layout">
805 <td class="left">
806 <tt>[4x int]*</tt><br/>
807 <tt>int (int *) *</tt><br/>
808 </td>
809 <td class="left">
810 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
811 four <tt>int</tt> values<br/>
812 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattner16fb0032005-02-19 02:22:14 +0000[diff] [blame]813 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]814 <tt>int</tt>.<br/>
815 </td>
816 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]817</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]818</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]819
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]820<!-- _______________________________________________________________________ -->
821<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]822<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]823
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]824<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]825
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]826<p>A packed type is a simple derived type that represents a vector
827of elements. Packed types are used when multiple primitive data
828are operated in parallel using a single instruction (SIMD).
829A packed type requires a size (number of
830elements) and an underlying primitive data type. Packed types are
831considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]832
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]833<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]834
835<pre>
836 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
837</pre>
838
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]839<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]840be any integral or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]841
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]842<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]843
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]844<table class="layout">
845 <tr class="layout">
846 <td class="left">
847 <tt>&lt;4 x int&gt;</tt><br/>
848 <tt>&lt;8 x float&gt;</tt><br/>
849 <tt>&lt;2 x uint&gt;</tt><br/>
850 </td>
851 <td class="left">
852 Packed vector of 4 integer values.<br/>
853 Packed vector of 8 floating-point values.<br/>
854 Packed vector of 2 unsigned integer values.<br/>
855 </td>
856 </tr>
857</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]858</div>
859
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]860<!-- _______________________________________________________________________ -->
861<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
862<div class="doc_text">
863
864<h5>Overview:</h5>
865
866<p>Opaque types are used to represent unknown types in the system. This
867corresponds (for example) to the C notion of a foward declared structure type.
868In LLVM, opaque types can eventually be resolved to any type (not just a
869structure type).</p>
870
871<h5>Syntax:</h5>
872
873<pre>
874 opaque
875</pre>
876
877<h5>Examples:</h5>
878
879<table class="layout">
880 <tr class="layout">
881 <td class="left">
882 <tt>opaque</tt>
883 </td>
884 <td class="left">
885 An opaque type.<br/>
886 </td>
887 </tr>
888</table>
889</div>
890
891
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]892<!-- *********************************************************************** -->
893<div class="doc_section"> <a name="constants">Constants</a> </div>
894<!-- *********************************************************************** -->
895
896<div class="doc_text">
897
898<p>LLVM has several different basic types of constants. This section describes
899them all and their syntax.</p>
900
901</div>
902
903<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]904<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]905
906<div class="doc_text">
907
908<dl>
909 <dt><b>Boolean constants</b></dt>
910
911 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
912 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
913 </dd>
914
915 <dt><b>Integer constants</b></dt>
916
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]917 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]918 href="#t_integer">integer</a> type. Negative numbers may be used with signed
919 integer types.
920 </dd>
921
922 <dt><b>Floating point constants</b></dt>
923
924 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
925 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]926 notation (see below). Floating point constants must have a <a
927 href="#t_floating">floating point</a> type. </dd>
928
929 <dt><b>Null pointer constants</b></dt>
930
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]931 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]932 and must be of <a href="#t_pointer">pointer type</a>.</dd>
933
934</dl>
935
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]936<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]937of floating point constants. For example, the form '<tt>double
9380x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
9394.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]940(and the only time that they are generated by the disassembler) is when a
941floating point constant must be emitted but it cannot be represented as a
942decimal floating point number. For example, NaN's, infinities, and other
943special values are represented in their IEEE hexadecimal format so that
944assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]945
946</div>
947
948<!-- ======================================================================= -->
949<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
950</div>
951
952<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]953<p>Aggregate constants arise from aggregation of simple constants
954and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]955
956<dl>
957 <dt><b>Structure constants</b></dt>
958
959 <dd>Structure constants are represented with notation similar to structure
960 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]961 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
962 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
963 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]964 types of elements must match those specified by the type.
965 </dd>
966
967 <dt><b>Array constants</b></dt>
968
969 <dd>Array constants are represented with notation similar to array type
970 definitions (a comma separated list of elements, surrounded by square brackets
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]971 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]972 constants must have <a href="#t_array">array type</a>, and the number and
973 types of elements must match those specified by the type.
974 </dd>
975
976 <dt><b>Packed constants</b></dt>
977
978 <dd>Packed constants are represented with notation similar to packed type
979 definitions (a comma separated list of elements, surrounded by
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]980 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; int 42,
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]981 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
982 href="#t_packed">packed type</a>, and the number and types of elements must
983 match those specified by the type.
984 </dd>
985
986 <dt><b>Zero initialization</b></dt>
987
988 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
989 value to zero of <em>any</em> type, including scalar and aggregate types.
990 This is often used to avoid having to print large zero initializers (e.g. for
991 large arrays), and is always exactly equivalent to using explicit zero
992 initializers.
993 </dd>
994</dl>
995
996</div>
997
998<!-- ======================================================================= -->
999<div class="doc_subsection">
1000 <a name="globalconstants">Global Variable and Function Addresses</a>
1001</div>
1002
1003<div class="doc_text">
1004
1005<p>The addresses of <a href="#globalvars">global variables</a> and <a
1006href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1007constants. These constants are explicitly referenced when the <a
1008href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1009href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1010file:</p>
1011
1012<pre>
1013 %X = global int 17
1014 %Y = global int 42
1015 %Z = global [2 x int*] [ int* %X, int* %Y ]
1016</pre>
1017
1018</div>
1019
1020<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1021<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1022<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1023 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1024 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1025 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1026
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1027 <p>Undefined values indicate to the compiler that the program is well defined
1028 no matter what value is used, giving the compiler more freedom to optimize.
1029 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1030</div>
1031
1032<!-- ======================================================================= -->
1033<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1034</div>
1035
1036<div class="doc_text">
1037
1038<p>Constant expressions are used to allow expressions involving other constants
1039to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1040href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1041that does not have side effects (e.g. load and call are not supported). The
1042following is the syntax for constant expressions:</p>
1043
1044<dl>
1045 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1046
1047 <dd>Cast a constant to another type.</dd>
1048
1049 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1050
1051 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1052 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1053 instruction, the index list may have zero or more indexes, which are required
1054 to make sense for the type of "CSTPTR".</dd>
1055
1056 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1057
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1058 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1059 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1060 binary</a> operations. The constraints on operands are the same as those for
1061 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1062 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1063</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1064</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1065
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1066<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1067<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1068<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1069
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1070<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1071
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1072<p>The LLVM instruction set consists of several different
1073classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1074instructions</a>, <a href="#binaryops">binary instructions</a>,
1075<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1076 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1077instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1078
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1079</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1080
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1081<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1082<div class="doc_subsection"> <a name="terminators">Terminator
1083Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1084
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1085<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1086
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1087<p>As mentioned <a href="#functionstructure">previously</a>, every
1088basic block in a program ends with a "Terminator" instruction, which
1089indicates which block should be executed after the current block is
1090finished. These terminator instructions typically yield a '<tt>void</tt>'
1091value: they produce control flow, not values (the one exception being
1092the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1093<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1094 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1095instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1096the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1097 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1098 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1099
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1100</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1101
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1102<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1103<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1104Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1105<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1106<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1107<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1108 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1109</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1110<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1111<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1112value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1113<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1114returns a value and then causes control flow, and one that just causes
1115control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1116<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1117<p>The '<tt>ret</tt>' instruction may return any '<a
1118 href="#t_firstclass">first class</a>' type. Notice that a function is
1119not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1120instruction inside of the function that returns a value that does not
1121match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1122<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1123<p>When the '<tt>ret</tt>' instruction is executed, control flow
1124returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1125 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1126the instruction after the call. If the caller was an "<a
1127 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1128at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1129returns a value, that value shall set the call or invoke instruction's
1130return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1131<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1132<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1133 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1134</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1135</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1136<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1137<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1138<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1139<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1140<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 Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1141</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1142<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1143<p>The '<tt>br</tt>' instruction is used to cause control flow to
1144transfer to a different basic block in the current function. There are
1145two forms of this instruction, corresponding to a conditional branch
1146and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1147<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1148<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1149single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1150unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1151value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1152<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1153<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1154argument is evaluated. If the value is <tt>true</tt>, control flows
1155to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1156control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1157<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1158<pre>Test:<br> %cond = <a href="#i_setcc">seteq</a> int %a, %b<br> br bool %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
1159 href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1160</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1161<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1162<div class="doc_subsubsection">
1163 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1164</div>
1165
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1166<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1167<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1168
1169<pre>
1170 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1171</pre>
1172
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1173<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1174
1175<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1176several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1177instruction, allowing a branch to occur to one of many possible
1178destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1179
1180
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1181<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1182
1183<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1184comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1185an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1186table is not allowed to contain duplicate constant entries.</p>
1187
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1188<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1189
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1190<p>The <tt>switch</tt> instruction specifies a table of values and
1191destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1192table is searched for the given value. If the value is found, control flow is
1193transfered to the corresponding destination; otherwise, control flow is
1194transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1195
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1196<h5>Implementation:</h5>
1197
1198<p>Depending on properties of the target machine and the particular
1199<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1200ways. For example, it could be generated as a series of chained conditional
1201branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1202
1203<h5>Example:</h5>
1204
1205<pre>
1206 <i>; Emulate a conditional br instruction</i>
1207 %Val = <a href="#i_cast">cast</a> bool %value to int
1208 switch int %Val, label %truedest [int 0, label %falsedest ]
1209
1210 <i>; Emulate an unconditional br instruction</i>
1211 switch uint 0, label %dest [ ]
1212
1213 <i>; Implement a jump table:</i>
1214 switch uint %val, label %otherwise [ uint 0, label %onzero
1215 uint 1, label %onone
1216 uint 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1217</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1218</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1219
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1220<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1221<div class="doc_subsubsection">
1222 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1223</div>
1224
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1225<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1226
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1227<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1228
1229<pre>
1230 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1231 to label &lt;normal label&gt; except label &lt;exception label&gt;
1232</pre>
1233
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1234<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1235
1236<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1237function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1238'<tt>normal</tt>' label or the
1239'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1240"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1241"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1242href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1243continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1244
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1245<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1246
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1247<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1248
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1249<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1250 <li>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1251 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1252 convention</a> the call should use. If none is specified, the call defaults
1253 to using C calling conventions.
1254 </li>
1255 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1256 function value being invoked. In most cases, this is a direct function
1257 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1258 an arbitrary pointer to function value.
1259 </li>
1260
1261 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1262 function to be invoked. </li>
1263
1264 <li>'<tt>function args</tt>': argument list whose types match the function
1265 signature argument types. If the function signature indicates the function
1266 accepts a variable number of arguments, the extra arguments can be
1267 specified. </li>
1268
1269 <li>'<tt>normal label</tt>': the label reached when the called function
1270 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1271
1272 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1273 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1274
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1275</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1276
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1277<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1278
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1279<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1280href="#i_call">call</a></tt>' instruction in most regards. The primary
1281difference is that it establishes an association with a label, which is used by
1282the runtime library to unwind the stack.</p>
1283
1284<p>This instruction is used in languages with destructors to ensure that proper
1285cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1286exception. Additionally, this is important for implementation of
1287'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1288
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1289<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1290<pre>
1291 %retval = invoke int %Test(int 15) to label %Continue
1292 except label %TestCleanup <i>; {int}:retval set</i>
1293 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
1294 except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1295</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1296</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1297
1298
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1299<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1300
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1301<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1302Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1303
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1304<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1305
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1306<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1307<pre>
1308 unwind
1309</pre>
1310
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1311<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1312
1313<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1314at the first callee in the dynamic call stack which used an <a
1315href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1316primarily used to implement exception handling.</p>
1317
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1318<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1319
1320<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1321immediately halt. The dynamic call stack is then searched for the first <a
1322href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1323execution continues at the "exceptional" destination block specified by the
1324<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1325dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1326</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1327
1328<!-- _______________________________________________________________________ -->
1329
1330<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1331Instruction</a> </div>
1332
1333<div class="doc_text">
1334
1335<h5>Syntax:</h5>
1336<pre>
1337 unreachable
1338</pre>
1339
1340<h5>Overview:</h5>
1341
1342<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1343instruction is used to inform the optimizer that a particular portion of the
1344code is not reachable. This can be used to indicate that the code after a
1345no-return function cannot be reached, and other facts.</p>
1346
1347<h5>Semantics:</h5>
1348
1349<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1350</div>
1351
1352
1353
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1354<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1355<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1356<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1357<p>Binary operators are used to do most of the computation in a
1358program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1359produce a single value. The operands might represent
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1360multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1361The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1362necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1363<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1364</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1365<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1366<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1367Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1368<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1369<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1370<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1371</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1372<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1373<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1374<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1375<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1376 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1377 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1378Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1379<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1380<p>The value produced is the integer or floating point sum of the two
1381operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1382<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1383<pre> &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1384</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1385</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1386<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1387<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1388Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1389<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1390<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1391<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1392</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1393<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1394<p>The '<tt>sub</tt>' instruction returns the difference of its two
1395operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1396<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1397instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1398<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1399<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1400 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1401values.
1402This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1403Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1404<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1405<p>The value produced is the integer or floating point difference of
1406the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1407<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1408<pre> &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1409 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1410</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1411</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1412<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1413<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1414Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1415<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1416<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1417<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1418</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1419<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1420<p>The '<tt>mul</tt>' instruction returns the product of its two
1421operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1422<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1423<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1424 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1425values.
1426This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1427Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1428<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1429<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1430two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1431<p>There is no signed vs unsigned multiplication. The appropriate
1432action is taken based on the type of the operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1433<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1434<pre> &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1435</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1436</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1437<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1438<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1439Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1440<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1441<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1442<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1443</pre>
1444<h5>Overview:</h5>
1445<p>The '<tt>div</tt>' instruction returns the quotient of its two
1446operands.</p>
1447<h5>Arguments:</h5>
1448<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1449 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1450values.
1451This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1452Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1453<h5>Semantics:</h5>
1454<p>The value produced is the integer or floating point quotient of the
1455two operands.</p>
1456<h5>Example:</h5>
1457<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1458</pre>
1459</div>
1460<!-- _______________________________________________________________________ -->
1461<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1462Instruction</a> </div>
1463<div class="doc_text">
1464<h5>Syntax:</h5>
1465<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1466</pre>
1467<h5>Overview:</h5>
1468<p>The '<tt>rem</tt>' instruction returns the remainder from the
1469division of its two operands.</p>
1470<h5>Arguments:</h5>
1471<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1472 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1473values.
1474This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1475Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1476<h5>Semantics:</h5>
1477<p>This returns the <i>remainder</i> of a division (where the result
1478has the same sign as the divisor), not the <i>modulus</i> (where the
1479result has the same sign as the dividend) of a value. For more
1480information about the difference, see: <a
1481 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1482Math Forum</a>.</p>
1483<h5>Example:</h5>
1484<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1485</pre>
1486</div>
1487<!-- _______________________________________________________________________ -->
1488<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1489Instructions</a> </div>
1490<div class="doc_text">
1491<h5>Syntax:</h5>
1492<pre> &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1493 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1494 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1495 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1496 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1497 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1498</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1499<h5>Overview:</h5>
1500<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1501value based on a comparison of their two operands.</p>
1502<h5>Arguments:</h5>
1503<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1504be of <a href="#t_firstclass">first class</a> type (it is not possible
1505to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1506or '<tt>void</tt>' values, etc...). Both arguments must have identical
1507types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1508<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1509<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1510value if both operands are equal.<br>
1511The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1512value if both operands are unequal.<br>
1513The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1514value if the first operand is less than the second operand.<br>
1515The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1516value if the first operand is greater than the second operand.<br>
1517The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1518value if the first operand is less than or equal to the second operand.<br>
1519The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1520value if the first operand is greater than or equal to the second
1521operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1522<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1523<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1524 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1525 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1526 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1527 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1528 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1529</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1530</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1531<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1532<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1533Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1534<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1535<p>Bitwise binary operators are used to do various forms of
1536bit-twiddling in a program. They are generally very efficient
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1537instructions and can commonly be strength reduced from other
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1538instructions. They require two operands, execute an operation on them,
1539and produce a single value. The resulting value of the bitwise binary
1540operators is always the same type as its first operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1541</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1542<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1543<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1544Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1545<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1546<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1547<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1548</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1549<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1550<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1551its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1552<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1553<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1554 href="#t_integral">integral</a> values. Both arguments must have
1555identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1556<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1557<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1558<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1559<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1560<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1561 <tbody>
1562 <tr>
1563 <td>In0</td>
1564 <td>In1</td>
1565 <td>Out</td>
1566 </tr>
1567 <tr>
1568 <td>0</td>
1569 <td>0</td>
1570 <td>0</td>
1571 </tr>
1572 <tr>
1573 <td>0</td>
1574 <td>1</td>
1575 <td>0</td>
1576 </tr>
1577 <tr>
1578 <td>1</td>
1579 <td>0</td>
1580 <td>0</td>
1581 </tr>
1582 <tr>
1583 <td>1</td>
1584 <td>1</td>
1585 <td>1</td>
1586 </tr>
1587 </tbody>
1588</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1589</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1590<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1591<pre> &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 &amp; %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1592 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1593 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1594</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1595</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1596<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1597<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1598<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1599<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1600<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1601</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1602<h5>Overview:</h5>
1603<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1604or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1605<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1606<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1607 href="#t_integral">integral</a> values. Both arguments must have
1608identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1609<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1610<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1611<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1612<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1613<table border="1" cellspacing="0" cellpadding="4">
1614 <tbody>
1615 <tr>
1616 <td>In0</td>
1617 <td>In1</td>
1618 <td>Out</td>
1619 </tr>
1620 <tr>
1621 <td>0</td>
1622 <td>0</td>
1623 <td>0</td>
1624 </tr>
1625 <tr>
1626 <td>0</td>
1627 <td>1</td>
1628 <td>1</td>
1629 </tr>
1630 <tr>
1631 <td>1</td>
1632 <td>0</td>
1633 <td>1</td>
1634 </tr>
1635 <tr>
1636 <td>1</td>
1637 <td>1</td>
1638 <td>1</td>
1639 </tr>
1640 </tbody>
1641</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1642</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1643<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1644<pre> &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1645 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1646 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1647</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1648</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1649<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1650<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1651Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1652<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1653<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1654<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1655</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1656<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1657<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1658or of its two operands. The <tt>xor</tt> is used to implement the
1659"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1660<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1661<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1662 href="#t_integral">integral</a> values. Both arguments must have
1663identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1664<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1665<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1666<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1667<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1668<table border="1" cellspacing="0" cellpadding="4">
1669 <tbody>
1670 <tr>
1671 <td>In0</td>
1672 <td>In1</td>
1673 <td>Out</td>
1674 </tr>
1675 <tr>
1676 <td>0</td>
1677 <td>0</td>
1678 <td>0</td>
1679 </tr>
1680 <tr>
1681 <td>0</td>
1682 <td>1</td>
1683 <td>1</td>
1684 </tr>
1685 <tr>
1686 <td>1</td>
1687 <td>0</td>
1688 <td>1</td>
1689 </tr>
1690 <tr>
1691 <td>1</td>
1692 <td>1</td>
1693 <td>0</td>
1694 </tr>
1695 </tbody>
1696</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1697</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1698<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1699<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1700<pre> &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1701 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1702 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1703 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1704</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1705</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1706<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1707<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1708Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1709<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1710<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1711<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1712</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1713<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1714<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1715the left a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1716<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1717<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1718 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1719type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1720<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1721<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1722<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1723<pre> &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 &lt;&lt; %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1724 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1725 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1726</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1727</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1728<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1729<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1730Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1731<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1732<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1733<pre> &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1734</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1735<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1736<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1737the right a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1738<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1739<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1740 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1741type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1742<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1743<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1744most significant bit is duplicated in the newly free'd bit positions.
1745If the first argument is unsigned, zero bits shall fill the empty
1746positions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1747<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1748<pre> &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 &gt;&gt; %var</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1749 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1750 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1751 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1752 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1753</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1754</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1755<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1756<div class="doc_subsection"> <a name="memoryops">Memory Access
1757Operations</a></div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1758<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1759<p>A key design point of an SSA-based representation is how it
1760represents memory. In LLVM, no memory locations are in SSA form, which
1761makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1762allocate, and free memory in LLVM.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1763</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1764<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1765<div class="doc_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>'
1766Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1767<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1768<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1769<pre> &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1770 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1771</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1772<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1773<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1774heap and returns a pointer to it.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1775<h5>Arguments:</h5>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]1776<p>The '<tt>malloc</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1777bytes of memory from the operating system and returns a pointer of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1778appropriate type to the program. The second form of the instruction is
1779a shorter version of the first instruction that defaults to allocating
1780one element.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1781<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1782<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1783<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1784a pointer is returned.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1785<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1786<pre> %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1787
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1788 %size = <a
1789 href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1790 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1791 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1792</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1793</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1794<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1795<div class="doc_subsubsection"> <a name="i_free">'<tt>free</tt>'
1796Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1797<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1798<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1799<pre> free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1800</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1801<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1802<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1803memory heap to be reallocated in the future.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1804<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1805<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1806<p>'<tt>value</tt>' shall be a pointer value that points to a value
1807that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1808instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1809<h5>Semantics:</h5>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1810<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1811after this instruction executes.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1812<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1813<pre> %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1814 free [4 x ubyte]* %array
1815</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1816</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1817<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1818<div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>'
1819Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1820<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1821<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1822<pre> &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1823 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1824</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1825<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1826<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1827stack frame of the procedure that is live until the current function
1828returns to its caller.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1829<h5>Arguments:</h5>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1830<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1831bytes of memory on the runtime stack, returning a pointer of the
1832appropriate type to the program. The second form of the instruction is
1833a shorter version of the first that defaults to allocating one element.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1834<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1835<h5>Semantics:</h5>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1836<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1837memory is automatically released when the function returns. The '<tt>alloca</tt>'
1838instruction is commonly used to represent automatic variables that must
1839have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]1840 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1841instructions), the memory is reclaimed.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1842<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1843<pre> %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1844 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1845</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1846</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1847<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1848<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1849Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1850<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1851<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1852<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 Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1853<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1854<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1855<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1856<p>The argument to the '<tt>load</tt>' instruction specifies the memory
1857address to load from. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1858 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1859marked as <tt>volatile</tt> then the optimizer is not allowed to modify
1860the number or order of execution of this <tt>load</tt> with other
1861volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1862instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1863<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1864<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1865<h5>Examples:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1866<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1867 <a
1868 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1869 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1870</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1871</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1872<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1873<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1874Instruction</a> </div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1875<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1876<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner12d456c2003-09-08 18:27:49 +0000[diff] [blame]1877 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1878</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1879<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1880<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1881<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1882<p>There are two arguments to the '<tt>store</tt>' instruction: a value
1883to store and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1884operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1885operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1886optimizer is not allowed to modify the number or order of execution of
1887this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1888 href="#i_store">store</a></tt> instructions.</p>
1889<h5>Semantics:</h5>
1890<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1891at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1892<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1893<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1894 <a
1895 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1896 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1897</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1898<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1899<div class="doc_subsubsection">
1900 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
1901</div>
1902
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1903<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1904<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1905<pre>
1906 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
1907</pre>
1908
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1909<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1910
1911<p>
1912The '<tt>getelementptr</tt>' instruction is used to get the address of a
1913subelement of an aggregate data structure.</p>
1914
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1915<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1916
1917<p>This instruction takes a list of integer constants that indicate what
1918elements of the aggregate object to index to. The actual types of the arguments
1919provided depend on the type of the first pointer argument. The
1920'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]1921levels of a structure or to a specific index in an array. When indexing into a
1922structure, only <tt>uint</tt>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1923integer constants are allowed. When indexing into an array or pointer,
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1924<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
1925
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1926<p>For example, let's consider a C code fragment and how it gets
1927compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1928
1929<pre>
1930 struct RT {
1931 char A;
1932 int B[10][20];
1933 char C;
1934 };
1935 struct ST {
1936 int X;
1937 double Y;
1938 struct RT Z;
1939 };
1940
1941 int *foo(struct ST *s) {
1942 return &amp;s[1].Z.B[5][13];
1943 }
1944</pre>
1945
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1946<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1947
1948<pre>
1949 %RT = type { sbyte, [10 x [20 x int]], sbyte }
1950 %ST = type { int, double, %RT }
1951
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]1952 implementation
1953
1954 int* %foo(%ST* %s) {
1955 entry:
1956 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1957 ret int* %reg
1958 }
1959</pre>
1960
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1961<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1962
1963<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1964on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1965and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
1966<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1967types require <tt>uint</tt> <b>constants</b>.</p>
1968
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1969<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1970type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
1971}</tt>' type, a structure. The second index indexes into the third element of
1972the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
1973sbyte }</tt>' type, another structure. The third index indexes into the second
1974element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
1975array. The two dimensions of the array are subscripted into, yielding an
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]1976'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1977to this element, thus computing a value of '<tt>int*</tt>' type.</p>
1978
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1979<p>Note that it is perfectly legal to index partially through a
1980structure, returning a pointer to an inner element. Because of this,
1981the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1982
1983<pre>
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1984 int* %foo(%ST* %s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1985 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
1986 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
1987 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1988 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
1989 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
1990 ret int* %t5
1991 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1992</pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1993<h5>Example:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1994<pre>
1995 <i>; yields [12 x ubyte]*:aptr</i>
1996 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
1997</pre>
1998
1999</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2000<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2001<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2002<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]2003<p>The instructions in this category are the "miscellaneous"
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2004instructions, which defy better classification.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2005</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2006<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2007<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2008Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2009<div class="doc_text">
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2010<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2011<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2012<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2013<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2014the SSA graph representing the function.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2015<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2016<p>The type of the incoming values are specified with the first type
2017field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2018as arguments, with one pair for each predecessor basic block of the
2019current block. Only values of <a href="#t_firstclass">first class</a>
2020type may be used as the value arguments to the PHI node. Only labels
2021may be used as the label arguments.</p>
2022<p>There must be no non-phi instructions between the start of a basic
2023block and the PHI instructions: i.e. PHI instructions must be first in
2024a basic block.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2025<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2026<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2027value specified by the parameter, depending on which basic block we
2028came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2029<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2030<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>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2031</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2032
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2033<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2034<div class="doc_subsubsection">
2035 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2036</div>
2037
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2038<div class="doc_text">
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2039
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2040<h5>Syntax:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2041
2042<pre>
2043 &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2044</pre>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2045
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2046<h5>Overview:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2047
2048<p>
2049The '<tt>cast</tt>' instruction is used as the primitive means to convert
2050integers to floating point, change data type sizes, and break type safety (by
2051casting pointers).
2052</p>
2053
2054
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2055<h5>Arguments:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2056
2057<p>
2058The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2059class value, and a type to cast it to, which must also be a <a
2060href="#t_firstclass">first class</a> type.
2061</p>
2062
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2063<h5>Semantics:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2064
2065<p>
2066This instruction follows the C rules for explicit casts when determining how the
2067data being cast must change to fit in its new container.
2068</p>
2069
2070<p>
2071When casting to bool, any value that would be considered true in the context of
2072a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2073all else are '<tt>false</tt>'.
2074</p>
2075
2076<p>
2077When extending an integral value from a type of one signness to another (for
2078example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2079<b>source</b> value is signed, and zero-extended if the source value is
2080unsigned. <tt>bool</tt> values are always zero extended into either zero or
2081one.
2082</p>
2083
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2084<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2085
2086<pre>
2087 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattnerd8f8ede2002-06-25 18:03:17 +0000[diff] [blame]2088 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2089</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2090</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2091
2092<!-- _______________________________________________________________________ -->
2093<div class="doc_subsubsection">
2094 <a name="i_select">'<tt>select</tt>' Instruction</a>
2095</div>
2096
2097<div class="doc_text">
2098
2099<h5>Syntax:</h5>
2100
2101<pre>
2102 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2103</pre>
2104
2105<h5>Overview:</h5>
2106
2107<p>
2108The '<tt>select</tt>' instruction is used to choose one value based on a
2109condition, without branching.
2110</p>
2111
2112
2113<h5>Arguments:</h5>
2114
2115<p>
2116The '<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.
2117</p>
2118
2119<h5>Semantics:</h5>
2120
2121<p>
2122If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2123value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2124</p>
2125
2126<h5>Example:</h5>
2127
2128<pre>
2129 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2130</pre>
2131</div>
2132
2133
2134
2135
2136
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2137<!-- _______________________________________________________________________ -->
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2138<div class="doc_subsubsection">
2139 <a name="i_call">'<tt>call</tt>' Instruction</a>
2140</div>
2141
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2142<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2143
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2144<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2145<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2146 &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2147</pre>
2148
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2149<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2150
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2151<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2152
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2153<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2154
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2155<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2156
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2157<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2158 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2159 <p>The optional "tail" marker indicates whether the callee function accesses
2160 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2161 function call is eligible for tail call optimization. Note that calls may
2162 be marked "tail" even if they do not occur before a <a
2163 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2164 </li>
2165 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2166 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2167 convention</a> the call should use. If none is specified, the call defaults
2168 to using C calling conventions.
2169 </li>
2170 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2171 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2172 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2173 signature. This type can be omitted if the function is not varargs and
2174 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2175 </li>
2176 <li>
2177 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2178 be invoked. In most cases, this is a direct function invocation, but
2179 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2180 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2181 </li>
2182 <li>
2183 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]2184 function signature argument types. All arguments must be of
2185 <a href="#t_firstclass">first class</a> type. If the function signature
2186 indicates the function accepts a variable number of arguments, the extra
2187 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2188 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2189</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2190
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2191<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2192
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2193<p>The '<tt>call</tt>' instruction is used to cause control flow to
2194transfer to a specified function, with its incoming arguments bound to
2195the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2196instruction in the called function, control flow continues with the
2197instruction after the function call, and the return value of the
2198function is bound to the result argument. This is a simpler case of
2199the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2200
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2201<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2202
2203<pre>
2204 %retval = call int %test(int %argc)
2205 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2206 %X = tail call int %foo()
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2207 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2208</pre>
2209
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2210</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2211
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2212<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2213<div class="doc_subsubsection">
2214 <a name="i_vanext">'<tt>vanext</tt>' Instruction</a>
2215</div>
2216
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2217<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2218
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2219<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2220
2221<pre>
2222 &lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
2223</pre>
2224
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2225<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2226
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2227<p>The '<tt>vanext</tt>' instruction is used to access arguments passed
2228through the "variable argument" area of a function call. It is used to
2229implement the <tt>va_arg</tt> macro in C.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2230
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2231<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2232
2233<p>This instruction takes a <tt>va_list</tt> value and the type of the
2234argument. It returns another <tt>va_list</tt>. The actual type of
2235<tt>va_list</tt> may be defined differently for different targets. Most targets
2236use a <tt>va_list</tt> type of <tt>sbyte*</tt> or some other pointer type.</p>
2237
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2238<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2239
2240<p>The '<tt>vanext</tt>' instruction advances the specified <tt>va_list</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2241past an argument of the specified type. In conjunction with the <a
2242 href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement
2243the <tt>va_arg</tt> macro available in C. For more information, see
2244the variable argument handling <a href="#int_varargs">Intrinsic
2245Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2246
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2247<p>It is legal for this instruction to be called in a function which
2248does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2249function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2250
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2251<p><tt>vanext</tt> is an LLVM instruction instead of an <a
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2252href="#intrinsics">intrinsic function</a> because it takes a type as an
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2253argument. The type refers to the current argument in the <tt>va_list</tt>; it
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2254tells the compiler how far on the stack it needs to advance to find the next
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2255argument.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2256
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2257<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2258
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2259<p>See the <a href="#int_varargs">variable argument processing</a>
2260section.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2261
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2262</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2263
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2264<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2265<div class="doc_subsubsection">
2266 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
2267</div>
2268
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2269<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2270
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2271<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2272
2273<pre>
2274 &lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
2275</pre>
2276
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2277<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2278
2279<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed through
2280the "variable argument" area of a function call. It is used to implement the
2281<tt>va_arg</tt> macro in C.</p>
2282
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2283<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2284
2285<p>This instruction takes a <tt>va_list</tt> value and the type of the
2286argument. It returns a value of the specified argument type. Again, the actual
2287type of <tt>va_list</tt> is target specific.</p>
2288
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2289<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2290
2291<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified type from
2292the specified <tt>va_list</tt>. In conjunction with the <a
2293href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to implement the
2294<tt>va_arg</tt> macro available in C. For more information, see the variable
2295argument handling <a href="#int_varargs">Intrinsic Functions</a>.</p>
2296
2297<p>It is legal for this instruction to be called in a function which does not
2298take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2299function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2300
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2301<p><tt>vaarg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2302href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2303argument.</p>
2304
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2305<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2306
2307<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2308
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2309</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2310
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2311<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2312<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2313<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2314
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2315<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2316
2317<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2318well known names and semantics and are required to follow certain
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2319restrictions. Overall, these instructions represent an extension mechanism for
2320the LLVM language that does not require changing all of the transformations in
2321LLVM to add to the language (or the bytecode reader/writer, the parser,
2322etc...).</p>
2323
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2324<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
2325prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2326this. Intrinsic functions must always be external functions: you cannot define
2327the body of intrinsic functions. Intrinsic functions may only be used in call
2328or invoke instructions: it is illegal to take the address of an intrinsic
2329function. Additionally, because intrinsic functions are part of the LLVM
2330language, it is required that they all be documented here if any are added.</p>
2331
2332
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2333<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner90391c12005-05-11 03:35:57 +0000[diff] [blame]2334href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2335</p>
2336
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2337</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2338
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2339<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2340<div class="doc_subsection">
2341 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2342</div>
2343
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2344<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2345
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2346<p>Variable argument support is defined in LLVM with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2347 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
2348intrinsic functions. These functions are related to the similarly
2349named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2350
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2351<p>All of these functions operate on arguments that use a
2352target-specific value type "<tt>va_list</tt>". The LLVM assembly
2353language reference manual does not define what this type is, so all
2354transformations should be prepared to handle intrinsics with any type
2355used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2356
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2357<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2358instruction and the variable argument handling intrinsic functions are
2359used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2360
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2361<pre>
2362int %test(int %X, ...) {
2363 ; Initialize variable argument processing
2364 %ap = call sbyte* %<a href="#i_va_start">llvm.va_start</a>()
2365
2366 ; Read a single integer argument
2367 %tmp = vaarg sbyte* %ap, int
2368
2369 ; Advance to the next argument
2370 %ap2 = vanext sbyte* %ap, int
2371
2372 ; Demonstrate usage of llvm.va_copy and llvm.va_end
2373 %aq = call sbyte* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)
2374 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq)
2375
2376 ; Stop processing of arguments.
2377 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)
2378 ret int %tmp
2379}
2380</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2381</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2382
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2383<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2384<div class="doc_subsubsection">
2385 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2386</div>
2387
2388
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2389<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2390<h5>Syntax:</h5>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2391<pre> declare &lt;va_list&gt; %llvm.va_start()<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2392<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2393<p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
2394for subsequent use by the variable argument intrinsics.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2395<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2396<p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2397macro available in C. In a target-dependent way, it initializes and
2398returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt>
2399will produce the first variable argument passed to the function. Unlike
2400the C <tt>va_start</tt> macro, this intrinsic does not need to know the
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2401last argument of the function; the compiler can figure that out.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2402<p>Note that this intrinsic function is only legal to be called from
2403within the body of a variable argument function.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2404</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2405
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2406<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2407<div class="doc_subsubsection">
2408 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2409</div>
2410
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2411<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2412<h5>Syntax:</h5>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2413<pre> declare void %llvm.va_end(&lt;va_list&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2414<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2415<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2416which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2417or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2418<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2419<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2420<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2421<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2422macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2423Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2424 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2425with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2426</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2427
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2428<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2429<div class="doc_subsubsection">
2430 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2431</div>
2432
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2433<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2434
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2435<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2436
2437<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2438 declare &lt;va_list&gt; %llvm.va_copy(&lt;va_list&gt; &lt;destarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2439</pre>
2440
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2441<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2442
2443<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
2444from the source argument list to the destination argument list.</p>
2445
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2446<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2447
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2448<p>The argument is the <tt>va_list</tt> to copy.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2449
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2450<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2451
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2452<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2453macro available in C. In a target-dependent way, it copies the source
2454<tt>va_list</tt> element into the returned list. This intrinsic is necessary
Chris Lattner53e5e2a2004-06-21 22:52:48 +0000[diff] [blame]2455because the <tt><a href="#i_va_start">llvm.va_start</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2456arbitrarily complex and require memory allocation, for example.</p>
2457
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2458</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2459
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2460<!-- ======================================================================= -->
2461<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2462 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2463</div>
2464
2465<div class="doc_text">
2466
2467<p>
2468LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2469Collection</a> requires the implementation and generation of these intrinsics.
2470These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2471stack</a>, as well as garbage collector implementations that require <a
2472href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2473Front-ends for type-safe garbage collected languages should generate these
2474intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2475href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2476</p>
2477</div>
2478
2479<!-- _______________________________________________________________________ -->
2480<div class="doc_subsubsection">
2481 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2482</div>
2483
2484<div class="doc_text">
2485
2486<h5>Syntax:</h5>
2487
2488<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2489 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2490</pre>
2491
2492<h5>Overview:</h5>
2493
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2494<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2495the code generator, and allows some metadata to be associated with it.</p>
2496
2497<h5>Arguments:</h5>
2498
2499<p>The first argument specifies the address of a stack object that contains the
2500root pointer. The second pointer (which must be either a constant or a global
2501value address) contains the meta-data to be associated with the root.</p>
2502
2503<h5>Semantics:</h5>
2504
2505<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2506location. At compile-time, the code generator generates information to allow
2507the runtime to find the pointer at GC safe points.
2508</p>
2509
2510</div>
2511
2512
2513<!-- _______________________________________________________________________ -->
2514<div class="doc_subsubsection">
2515 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2516</div>
2517
2518<div class="doc_text">
2519
2520<h5>Syntax:</h5>
2521
2522<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2523 declare sbyte* %llvm.gcread(sbyte** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2524</pre>
2525
2526<h5>Overview:</h5>
2527
2528<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2529locations, allowing garbage collector implementations that require read
2530barriers.</p>
2531
2532<h5>Arguments:</h5>
2533
2534<p>The argument is the address to read from, which should be an address
2535allocated from the garbage collector.</p>
2536
2537<h5>Semantics:</h5>
2538
2539<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2540instruction, but may be replaced with substantially more complex code by the
2541garbage collector runtime, as needed.</p>
2542
2543</div>
2544
2545
2546<!-- _______________________________________________________________________ -->
2547<div class="doc_subsubsection">
2548 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2549</div>
2550
2551<div class="doc_text">
2552
2553<h5>Syntax:</h5>
2554
2555<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2556 declare void %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2557</pre>
2558
2559<h5>Overview:</h5>
2560
2561<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2562locations, allowing garbage collector implementations that require write
2563barriers (such as generational or reference counting collectors).</p>
2564
2565<h5>Arguments:</h5>
2566
2567<p>The first argument is the reference to store, and the second is the heap
2568location to store to.</p>
2569
2570<h5>Semantics:</h5>
2571
2572<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2573instruction, but may be replaced with substantially more complex code by the
2574garbage collector runtime, as needed.</p>
2575
2576</div>
2577
2578
2579
2580<!-- ======================================================================= -->
2581<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2582 <a name="int_codegen">Code Generator Intrinsics</a>
2583</div>
2584
2585<div class="doc_text">
2586<p>
2587These intrinsics are provided by LLVM to expose special features that may only
2588be implemented with code generator support.
2589</p>
2590
2591</div>
2592
2593<!-- _______________________________________________________________________ -->
2594<div class="doc_subsubsection">
2595 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2596</div>
2597
2598<div class="doc_text">
2599
2600<h5>Syntax:</h5>
2601<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2602 declare void* %llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2603</pre>
2604
2605<h5>Overview:</h5>
2606
2607<p>
2608The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2609indicating the return address of the current function or one of its callers.
2610</p>
2611
2612<h5>Arguments:</h5>
2613
2614<p>
2615The argument to this intrinsic indicates which function to return the address
2616for. Zero indicates the calling function, one indicates its caller, etc. The
2617argument is <b>required</b> to be a constant integer value.
2618</p>
2619
2620<h5>Semantics:</h5>
2621
2622<p>
2623The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2624the return address of the specified call frame, or zero if it cannot be
2625identified. The value returned by this intrinsic is likely to be incorrect or 0
2626for arguments other than zero, so it should only be used for debugging purposes.
2627</p>
2628
2629<p>
2630Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]2631aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2632source-language caller.
2633</p>
2634</div>
2635
2636
2637<!-- _______________________________________________________________________ -->
2638<div class="doc_subsubsection">
2639 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2640</div>
2641
2642<div class="doc_text">
2643
2644<h5>Syntax:</h5>
2645<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2646 declare void* %llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2647</pre>
2648
2649<h5>Overview:</h5>
2650
2651<p>
2652The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2653pointer value for the specified stack frame.
2654</p>
2655
2656<h5>Arguments:</h5>
2657
2658<p>
2659The argument to this intrinsic indicates which function to return the frame
2660pointer for. Zero indicates the calling function, one indicates its caller,
2661etc. The argument is <b>required</b> to be a constant integer value.
2662</p>
2663
2664<h5>Semantics:</h5>
2665
2666<p>
2667The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2668the frame address of the specified call frame, or zero if it cannot be
2669identified. The value returned by this intrinsic is likely to be incorrect or 0
2670for arguments other than zero, so it should only be used for debugging purposes.
2671</p>
2672
2673<p>
2674Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]2675aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2676source-language caller.
2677</p>
2678</div>
2679
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2680<!-- _______________________________________________________________________ -->
2681<div class="doc_subsubsection">
2682 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
2683</div>
2684
2685<div class="doc_text">
2686
2687<h5>Syntax:</h5>
2688<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2689 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
2690 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2691</pre>
2692
2693<h5>Overview:</h5>
2694
2695
2696<p>
2697The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2698a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
2699no
2700effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]2701characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2702</p>
2703
2704<h5>Arguments:</h5>
2705
2706<p>
2707<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
2708determining if the fetch should be for a read (0) or write (1), and
2709<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]2710locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2711<tt>locality</tt> arguments must be constant integers.
2712</p>
2713
2714<h5>Semantics:</h5>
2715
2716<p>
2717This intrinsic does not modify the behavior of the program. In particular,
2718prefetches cannot trap and do not produce a value. On targets that support this
2719intrinsic, the prefetch can provide hints to the processor cache for better
2720performance.
2721</p>
2722
2723</div>
2724
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2725<!-- _______________________________________________________________________ -->
2726<div class="doc_subsubsection">
2727 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
2728</div>
2729
2730<div class="doc_text">
2731
2732<h5>Syntax:</h5>
2733<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2734 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2735</pre>
2736
2737<h5>Overview:</h5>
2738
2739
2740<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2741The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
2742(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2743code to simulators and other tools. The method is target specific, but it is
2744expected that the marker will use exported symbols to transmit the PC of the marker.
2745The marker makes no guaranties that it will remain with any specific instruction
2746after optimizations. It is possible that the presense of a marker will inhibit
2747optimizations. The intended use is to be inserted after optmizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame^]2748correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2749</p>
2750
2751<h5>Arguments:</h5>
2752
2753<p>
2754<tt>id</tt> is a numerical id identifying the marker.
2755</p>
2756
2757<h5>Semantics:</h5>
2758
2759<p>
2760This intrinsic does not modify the behavior of the program. Backends that do not
2761support this intrinisic may ignore it.
2762</p>
2763
2764</div>
2765
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2766
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2767<!-- ======================================================================= -->
2768<div class="doc_subsection">
2769 <a name="int_os">Operating System Intrinsics</a>
2770</div>
2771
2772<div class="doc_text">
2773<p>
2774These intrinsics are provided by LLVM to support the implementation of
2775operating system level code.
2776</p>
2777
2778</div>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2779
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2780<!-- _______________________________________________________________________ -->
2781<div class="doc_subsubsection">
2782 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2783</div>
2784
2785<div class="doc_text">
2786
2787<h5>Syntax:</h5>
2788<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2789 declare &lt;integer type&gt; %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2790</pre>
2791
2792<h5>Overview:</h5>
2793
2794<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2795The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2796I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2797</p>
2798
2799<h5>Arguments:</h5>
2800
2801<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2802The argument to this intrinsic indicates the hardware I/O address from which
2803to read the data. The address is in the hardware I/O address namespace (as
2804opposed to being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2805</p>
2806
2807<h5>Semantics:</h5>
2808
2809<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2810The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2811specified by <i>address</i> and returns the value. The address and return
2812value must be integers, but the size is dependent upon the platform upon which
2813the program is code generated. For example, on x86, the address must be an
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2814unsigned 16-bit value, and the return value must be 8, 16, or 32 bits.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2815</p>
2816
2817</div>
2818
2819<!-- _______________________________________________________________________ -->
2820<div class="doc_subsubsection">
2821 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2822</div>
2823
2824<div class="doc_text">
2825
2826<h5>Syntax:</h5>
2827<pre>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]2828 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
2829 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
2830 &lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2831</pre>
2832
2833<h5>Overview:</h5>
2834
2835<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2836The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2837I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2838</p>
2839
2840<h5>Arguments:</h5>
2841
2842<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2843The first argument is the value to write to the I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2844</p>
2845
2846<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2847The second argument indicates the hardware I/O address to which data should be
2848written. The address is in the hardware I/O address namespace (as opposed to
2849being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2850</p>
2851
2852<h5>Semantics:</h5>
2853
2854<p>
2855The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2856specified by <i>address</i>. The address and value must be integers, but the
2857size is dependent upon the platform upon which the program is code generated.
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2858For example, on x86, the address must be an unsigned 16-bit value, and the
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2859value written must be 8, 16, or 32 bits in length.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2860</p>
2861
2862</div>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2863
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2864<!-- _______________________________________________________________________ -->
2865<div class="doc_subsubsection">
2866 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
2867</div>
2868
2869<div class="doc_text">
2870
2871<h5>Syntax:</h5>
2872<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2873 declare &lt;result&gt; %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2874</pre>
2875
2876<h5>Overview:</h5>
2877
2878<p>
2879The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
2880address.
2881</p>
2882
2883<h5>Arguments:</h5>
2884
2885<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2886The argument to this intrinsic is a pointer indicating the memory address from
2887which to read the data. The data must be a
2888<a href="#t_firstclass">first class</a> type.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2889</p>
2890
2891<h5>Semantics:</h5>
2892
2893<p>
2894The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2895location specified by <i>pointer</i> and returns the value. The argument must
2896be a pointer, and the return value must be a
2897<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2898may not support I/O on all first class types. For example, 32-bit processors
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2899may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2900</p>
2901
2902<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2903This intrinsic enforces an in-order memory model for llvm.readio and
2904llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2905scheduled processors may execute loads and stores out of order, re-ordering at
2906run time accesses to memory mapped I/O registers. Using these intrinsics
2907ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2908</p>
2909
2910</div>
2911
2912<!-- _______________________________________________________________________ -->
2913<div class="doc_subsubsection">
2914 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
2915</div>
2916
2917<div class="doc_text">
2918
2919<h5>Syntax:</h5>
2920<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2921 declare void %llvm.writeio (&lt;ty1&gt; &lt;value&gt;, &lt;ty2&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2922</pre>
2923
2924<h5>Overview:</h5>
2925
2926<p>
2927The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
2928mapped I/O address.
2929</p>
2930
2931<h5>Arguments:</h5>
2932
2933<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2934The first argument is the value to write to the memory mapped I/O location.
2935The second argument is a pointer indicating the memory address to which the
2936data should be written.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2937</p>
2938
2939<h5>Semantics:</h5>
2940
2941<p>
2942The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2943I/O address specified by <i>pointer</i>. The value must be a
2944<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2945may not support I/O on all first class types. For example, 32-bit processors
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2946may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2947</p>
2948
2949<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2950This intrinsic enforces an in-order memory model for llvm.readio and
2951llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2952scheduled processors may execute loads and stores out of order, re-ordering at
2953run time accesses to memory mapped I/O registers. Using these intrinsics
2954ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2955</p>
2956
2957</div>
2958
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2959<!-- ======================================================================= -->
2960<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2961 <a name="int_libc">Standard C Library Intrinsics</a>
2962</div>
2963
2964<div class="doc_text">
2965<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2966LLVM provides intrinsics for a few important standard C library functions.
2967These intrinsics allow source-language front-ends to pass information about the
2968alignment of the pointer arguments to the code generator, providing opportunity
2969for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2970</p>
2971
2972</div>
2973
2974<!-- _______________________________________________________________________ -->
2975<div class="doc_subsubsection">
2976 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
2977</div>
2978
2979<div class="doc_text">
2980
2981<h5>Syntax:</h5>
2982<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]2983 declare void %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
2984 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2985</pre>
2986
2987<h5>Overview:</h5>
2988
2989<p>
2990The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
2991location to the destination location.
2992</p>
2993
2994<p>
2995Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
2996does not return a value, and takes an extra alignment argument.
2997</p>
2998
2999<h5>Arguments:</h5>
3000
3001<p>
3002The first argument is a pointer to the destination, the second is a pointer to
3003the source. The third argument is an (arbitrarily sized) integer argument
3004specifying the number of bytes to copy, and the fourth argument is the alignment
3005of the source and destination locations.
3006</p>
3007
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3008<p>
3009If the call to this intrinisic has an alignment value that is not 0 or 1, then
3010the caller guarantees that the size of the copy is a multiple of the alignment
3011and that both the source and destination pointers are aligned to that boundary.
3012</p>
3013
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3014<h5>Semantics:</h5>
3015
3016<p>
3017The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3018location to the destination location, which are not allowed to overlap. It
3019copies "len" bytes of memory over. If the argument is known to be aligned to
3020some boundary, this can be specified as the fourth argument, otherwise it should
3021be set to 0 or 1.
3022</p>
3023</div>
3024
3025
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3026<!-- _______________________________________________________________________ -->
3027<div class="doc_subsubsection">
3028 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3029</div>
3030
3031<div class="doc_text">
3032
3033<h5>Syntax:</h5>
3034<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3035 declare void %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3036 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3037</pre>
3038
3039<h5>Overview:</h5>
3040
3041<p>
3042The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
3043location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
3044intrinsic but allows the two memory locations to overlap.
3045</p>
3046
3047<p>
3048Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
3049does not return a value, and takes an extra alignment argument.
3050</p>
3051
3052<h5>Arguments:</h5>
3053
3054<p>
3055The first argument is a pointer to the destination, the second is a pointer to
3056the source. The third argument is an (arbitrarily sized) integer argument
3057specifying the number of bytes to copy, and the fourth argument is the alignment
3058of the source and destination locations.
3059</p>
3060
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3061<p>
3062If the call to this intrinisic has an alignment value that is not 0 or 1, then
3063the caller guarantees that the size of the copy is a multiple of the alignment
3064and that both the source and destination pointers are aligned to that boundary.
3065</p>
3066
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3067<h5>Semantics:</h5>
3068
3069<p>
3070The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
3071location to the destination location, which may overlap. It
3072copies "len" bytes of memory over. If the argument is known to be aligned to
3073some boundary, this can be specified as the fourth argument, otherwise it should
3074be set to 0 or 1.
3075</p>
3076</div>
3077
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3078
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3079<!-- _______________________________________________________________________ -->
3080<div class="doc_subsubsection">
3081 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
3082</div>
3083
3084<div class="doc_text">
3085
3086<h5>Syntax:</h5>
3087<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3088 declare void %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3089 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3090</pre>
3091
3092<h5>Overview:</h5>
3093
3094<p>
3095The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
3096byte value.
3097</p>
3098
3099<p>
3100Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3101does not return a value, and takes an extra alignment argument.
3102</p>
3103
3104<h5>Arguments:</h5>
3105
3106<p>
3107The first argument is a pointer to the destination to fill, the second is the
3108byte value to fill it with, the third argument is an (arbitrarily sized) integer
3109argument specifying the number of bytes to fill, and the fourth argument is the
3110known alignment of destination location.
3111</p>
3112
3113<p>
3114If the call to this intrinisic has an alignment value that is not 0 or 1, then
3115the caller guarantees that the size of the copy is a multiple of the alignment
3116and that the destination pointer is aligned to that boundary.
3117</p>
3118
3119<h5>Semantics:</h5>
3120
3121<p>
3122The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
3123destination location. If the argument is known to be aligned to some boundary,
3124this can be specified as the fourth argument, otherwise it should be set to 0 or
31251.
3126</p>
3127</div>
3128
3129
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3130<!-- _______________________________________________________________________ -->
3131<div class="doc_subsubsection">
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3132 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
3133</div>
3134
3135<div class="doc_text">
3136
3137<h5>Syntax:</h5>
3138<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3139 declare bool %llvm.isunordered(&lt;float or double&gt; Val1, &lt;float or double&gt; Val2)
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3140</pre>
3141
3142<h5>Overview:</h5>
3143
3144<p>
3145The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
3146specified floating point values is a NAN.
3147</p>
3148
3149<h5>Arguments:</h5>
3150
3151<p>
3152The arguments are floating point numbers of the same type.
3153</p>
3154
3155<h5>Semantics:</h5>
3156
3157<p>
3158If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3159false.
3160</p>
3161</div>
3162
3163
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3164<!-- ======================================================================= -->
3165<div class="doc_subsection">
3166 <a name="int_count">Bit Counting Intrinsics</a>
3167</div>
3168
3169<div class="doc_text">
3170<p>
3171LLVM provides intrinsics for a few important bit counting operations.
3172These allow efficient code generation for some algorithms.
3173</p>
3174
3175</div>
3176
3177<!-- _______________________________________________________________________ -->
3178<div class="doc_subsubsection">
3179 <a name="int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic</a>
3180</div>
3181
3182<div class="doc_text">
3183
3184<h5>Syntax:</h5>
3185<pre>
3186 declare int %llvm.ctpop(int &lt;src&gt;)
3187
3188</pre>
3189
3190<h5>Overview:</h5>
3191
3192<p>
3193The '<tt>llvm.ctpop</tt>' intrinsic counts the number of ones in a variable.
3194</p>
3195
3196<h5>Arguments:</h5>
3197
3198<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3199The only argument is the value to be counted. The argument may be of any
3200integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3201</p>
3202
3203<h5>Semantics:</h5>
3204
3205<p>
3206The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3207</p>
3208</div>
3209
3210<!-- _______________________________________________________________________ -->
3211<div class="doc_subsubsection">
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3212 <a name="int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic</a>
3213</div>
3214
3215<div class="doc_text">
3216
3217<h5>Syntax:</h5>
3218<pre>
3219 declare int %llvm.ctlz(int &lt;src&gt;)
3220
3221</pre>
3222
3223<h5>Overview:</h5>
3224
3225<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3226The '<tt>llvm.ctlz</tt>' intrinsic counts the number of leading zeros in a
3227variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3228</p>
3229
3230<h5>Arguments:</h5>
3231
3232<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3233The only argument is the value to be counted. The argument may be of any
3234integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3235</p>
3236
3237<h5>Semantics:</h5>
3238
3239<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3240The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
3241in a variable. If the src == 0 then the result is the size in bits of the type
3242of src. For example, <tt>llvm.cttz(int 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3243</p>
3244</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3245
3246
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3247
3248<!-- _______________________________________________________________________ -->
3249<div class="doc_subsubsection">
3250 <a name="int_cttz">'<tt>llvm.cttz</tt>' Intrinsic</a>
3251</div>
3252
3253<div class="doc_text">
3254
3255<h5>Syntax:</h5>
3256<pre>
3257 declare int %llvm.cttz(int &lt;src&gt;)
3258
3259</pre>
3260
3261<h5>Overview:</h5>
3262
3263<p>
3264The '<tt>llvm.cttz</tt>' intrinsic counts the number of trailing zeros.
3265</p>
3266
3267<h5>Arguments:</h5>
3268
3269<p>
3270The only argument is the value to be counted. The argument may be of any
3271integer type. The return type must match the argument type.
3272</p>
3273
3274<h5>Semantics:</h5>
3275
3276<p>
3277The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
3278in a variable. If the src == 0 then the result is the size in bits of the type
3279of src. For example, <tt>llvm.cttz(2) = 1</tt>.
3280</p>
3281</div>
3282
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3283<!-- ======================================================================= -->
3284<div class="doc_subsection">
3285 <a name="int_debugger">Debugger Intrinsics</a>
3286</div>
3287
3288<div class="doc_text">
3289<p>
3290The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3291are described in the <a
3292href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3293Debugging</a> document.
3294</p>
3295</div>
3296
3297
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3298<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3299<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]3300<address>
3301 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
3302 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
3303 <a href="http://validator.w3.org/check/referer"><img
3304 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
3305
3306 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
3307 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
3308 Last modified: $Date$
3309</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3310</body>
3311</html>