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gerrit-public.fairphone.software / toolchain / llvm-project / 33b73f9cfc3706fd2fff3cb1605084e449b526ad / . / llvm / docs / LangRef.html
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5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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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>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]26 <li><a href="#functionstructure">Functions</a></li>
27 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]28 </ol>
29 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]30 <li><a href="#typesystem">Type System</a>
31 <ol>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]32 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]33 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]34 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]35 </ol>
36 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]37 <li><a href="#t_derived">Derived Types</a>
38 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]39 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]40 <li><a href="#t_function">Function Type</a></li>
41 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]42 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]43 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]44 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]45 </ol>
46 </li>
47 </ol>
48 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]49 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]50 <ol>
51 <li><a href="#simpleconstants">Simple Constants</a>
52 <li><a href="#aggregateconstants">Aggregate Constants</a>
53 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
54 <li><a href="#undefvalues">Undefined Values</a>
55 <li><a href="#constantexprs">Constant Expressions</a>
56 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]57 </li>
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]58 <li><a href="#othervalues">Other Values</a>
59 <ol>
60 <li><a href="#inlineasm">Inline Assembler Expressions</a>
61 </ol>
62 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]63 <li><a href="#instref">Instruction Reference</a>
64 <ol>
65 <li><a href="#terminators">Terminator Instructions</a>
66 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]67 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
68 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]69 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
70 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]71 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]72 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]73 </ol>
74 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]75 <li><a href="#binaryops">Binary Operations</a>
76 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]77 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
78 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
79 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
80 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
81 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]82 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]83 </ol>
84 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]85 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
86 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]87 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]88 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]89 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
90 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
91 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]92 </ol>
93 </li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]94 <li><a href="#vectorops">Vector Operations</a>
95 <ol>
96 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
97 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
98 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Tanya Lattnerb138bbe2006-04-14 19:24:33 +0000[diff] [blame]99 <li><a href="#i_vsetint">'<tt>vsetint</tt>' Instruction</a></li>
100 <li><a href="#i_vsetfp">'<tt>vsetfp</tt>' Instruction</a></li>
101 <li><a href="#i_vselect">'<tt>vselect</tt>' Instruction</a></li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]102 </ol>
103 </li>
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]104 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]105 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]106 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
107 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
108 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]109 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
110 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
111 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]112 </ol>
113 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]114 <li><a href="#otherops">Other Operations</a>
115 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]116 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]117 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]118 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]119 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]120 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]121 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]122 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]123 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]124 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]125 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]126 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]127 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
128 <ol>
129 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
130 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
131 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
132 </ol>
133 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]134 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
135 <ol>
136 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
137 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
138 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
139 </ol>
140 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]141 <li><a href="#int_codegen">Code Generator Intrinsics</a>
142 <ol>
143 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
144 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]145 <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
146 <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]147 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]148 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]149 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]150 </ol>
151 </li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]152 <li><a href="#int_libc">Standard C Library Intrinsics</a>
153 <ol>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]154 <li><a href="#i_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
155 <li><a href="#i_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
156 <li><a href="#i_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]157 <li><a href="#i_isunordered">'<tt>llvm.isunordered.*</tt>' Intrinsic</a></li>
158 <li><a href="#i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame^]159 <li><a href="#i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]160 </ol>
161 </li>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]162 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]163 <ol>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]164 <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]165 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
166 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
167 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]168 </ol>
169 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]170 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]171 </ol>
172 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]173</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]174
175<div class="doc_author">
176 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
177 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]178</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]179
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]180<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]181<div class="doc_section"> <a name="abstract">Abstract </a></div>
182<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]183
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]184<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]185<p>This document is a reference manual for the LLVM assembly language.
186LLVM is an SSA based representation that provides type safety,
187low-level operations, flexibility, and the capability of representing
188'all' high-level languages cleanly. It is the common code
189representation used throughout all phases of the LLVM compilation
190strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]191</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]192
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]193<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]194<div class="doc_section"> <a name="introduction">Introduction</a> </div>
195<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]196
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]197<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]198
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]199<p>The LLVM code representation is designed to be used in three
200different forms: as an in-memory compiler IR, as an on-disk bytecode
201representation (suitable for fast loading by a Just-In-Time compiler),
202and as a human readable assembly language representation. This allows
203LLVM to provide a powerful intermediate representation for efficient
204compiler transformations and analysis, while providing a natural means
205to debug and visualize the transformations. The three different forms
206of LLVM are all equivalent. This document describes the human readable
207representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]208
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]209<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]210while being expressive, typed, and extensible at the same time. It
211aims to be a "universal IR" of sorts, by being at a low enough level
212that high-level ideas may be cleanly mapped to it (similar to how
213microprocessors are "universal IR's", allowing many source languages to
214be mapped to them). By providing type information, LLVM can be used as
215the target of optimizations: for example, through pointer analysis, it
216can be proven that a C automatic variable is never accessed outside of
217the current function... allowing it to be promoted to a simple SSA
218value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]219
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]220</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]221
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]222<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]223<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]224
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]225<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]226
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]227<p>It is important to note that this document describes 'well formed'
228LLVM assembly language. There is a difference between what the parser
229accepts and what is considered 'well formed'. For example, the
230following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]231
232<pre>
233 %x = <a href="#i_add">add</a> int 1, %x
234</pre>
235
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]236<p>...because the definition of <tt>%x</tt> does not dominate all of
237its uses. The LLVM infrastructure provides a verification pass that may
238be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]239automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]240the optimizer before it outputs bytecode. The violations pointed out
241by the verifier pass indicate bugs in transformation passes or input to
242the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]243
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]244<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]245
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]246<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]247<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]248<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]249
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]250<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]251
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]252<p>LLVM uses three different forms of identifiers, for different
253purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]254
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]255<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]256 <li>Named values are represented as a string of characters with a '%' prefix.
257 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
258 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
259 Identifiers which require other characters in their names can be surrounded
260 with quotes. In this way, anything except a <tt>"</tt> character can be used
261 in a name.</li>
262
263 <li>Unnamed values are represented as an unsigned numeric value with a '%'
264 prefix. For example, %12, %2, %44.</li>
265
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]266 <li>Constants, which are described in a <a href="#constants">section about
267 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]268</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]269
270<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
271don't need to worry about name clashes with reserved words, and the set of
272reserved words may be expanded in the future without penalty. Additionally,
273unnamed identifiers allow a compiler to quickly come up with a temporary
274variable without having to avoid symbol table conflicts.</p>
275
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]276<p>Reserved words in LLVM are very similar to reserved words in other
277languages. There are keywords for different opcodes ('<tt><a
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]278href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
279href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
280href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
281and others. These reserved words cannot conflict with variable names, because
282none of them start with a '%' character.</p>
283
284<p>Here is an example of LLVM code to multiply the integer variable
285'<tt>%X</tt>' by 8:</p>
286
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]287<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]288
289<pre>
290 %result = <a href="#i_mul">mul</a> uint %X, 8
291</pre>
292
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]293<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]294
295<pre>
296 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
297</pre>
298
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]299<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]300
301<pre>
302 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
303 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
304 %result = <a href="#i_add">add</a> uint %1, %1
305</pre>
306
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]307<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
308important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]309
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]310<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]311
312 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
313 line.</li>
314
315 <li>Unnamed temporaries are created when the result of a computation is not
316 assigned to a named value.</li>
317
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]318 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]319
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]320</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]321
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]322<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]323demonstrating instructions, we will follow an instruction with a comment that
324defines the type and name of value produced. Comments are shown in italic
325text.</p>
326
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]327</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]328
329<!-- *********************************************************************** -->
330<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
331<!-- *********************************************************************** -->
332
333<!-- ======================================================================= -->
334<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
335</div>
336
337<div class="doc_text">
338
339<p>LLVM programs are composed of "Module"s, each of which is a
340translation unit of the input programs. Each module consists of
341functions, global variables, and symbol table entries. Modules may be
342combined together with the LLVM linker, which merges function (and
343global variable) definitions, resolves forward declarations, and merges
344symbol table entries. Here is an example of the "hello world" module:</p>
345
346<pre><i>; Declare the string constant as a global constant...</i>
347<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
348 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
349
350<i>; External declaration of the puts function</i>
351<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
352
Chris Lattnerd2d29a02006-06-13 03:05:47 +0000[diff] [blame]353<i>; Global variable / Function body section separator</i>
354implementation
355
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]356<i>; Definition of main function</i>
357int %main() { <i>; int()* </i>
358 <i>; Convert [13x sbyte]* to sbyte *...</i>
359 %cast210 = <a
360 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
361
362 <i>; Call puts function to write out the string to stdout...</i>
363 <a
364 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
365 <a
366 href="#i_ret">ret</a> int 0<br>}<br></pre>
367
368<p>This example is made up of a <a href="#globalvars">global variable</a>
369named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
370function, and a <a href="#functionstructure">function definition</a>
371for "<tt>main</tt>".</p>
372
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]373<p>In general, a module is made up of a list of global values,
374where both functions and global variables are global values. Global values are
375represented by a pointer to a memory location (in this case, a pointer to an
376array of char, and a pointer to a function), and have one of the following <a
377href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]378
Chris Lattnerd2d29a02006-06-13 03:05:47 +0000[diff] [blame]379<p>Due to a limitation in the current LLVM assembly parser (it is limited by
380one-token lookahead), modules are split into two pieces by the "implementation"
381keyword. Global variable prototypes and definitions must occur before the
382keyword, and function definitions must occur after it. Function prototypes may
383occur either before or after it. In the future, the implementation keyword may
384become a noop, if the parser gets smarter.</p>
385
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]386</div>
387
388<!-- ======================================================================= -->
389<div class="doc_subsection">
390 <a name="linkage">Linkage Types</a>
391</div>
392
393<div class="doc_text">
394
395<p>
396All Global Variables and Functions have one of the following types of linkage:
397</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]398
399<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]400
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]401 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]402
403 <dd>Global values with internal linkage are only directly accessible by
404 objects in the current module. In particular, linking code into a module with
405 an internal global value may cause the internal to be renamed as necessary to
406 avoid collisions. Because the symbol is internal to the module, all
407 references can be updated. This corresponds to the notion of the
408 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]409 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]410
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]411 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]412
413 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
414 the twist that linking together two modules defining the same
415 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
416 is typically used to implement inline functions. Unreferenced
417 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]418 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]419
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]420 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]421
422 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
423 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
424 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]425 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]426
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]427 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]428
429 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
430 pointer to array type. When two global variables with appending linkage are
431 linked together, the two global arrays are appended together. This is the
432 LLVM, typesafe, equivalent of having the system linker append together
433 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]434 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]435
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]436 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]437
438 <dd>If none of the above identifiers are used, the global is externally
439 visible, meaning that it participates in linkage and can be used to resolve
440 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]441 </dd>
442</dl>
443
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]444<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
445variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
446variable and was linked with this one, one of the two would be renamed,
447preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
448external (i.e., lacking any linkage declarations), they are accessible
449outside of the current module. It is illegal for a function <i>declaration</i>
450to have any linkage type other than "externally visible".</a></p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]451
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]452</div>
453
454<!-- ======================================================================= -->
455<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]456 <a name="callingconv">Calling Conventions</a>
457</div>
458
459<div class="doc_text">
460
461<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
462and <a href="#i_invoke">invokes</a> can all have an optional calling convention
463specified for the call. The calling convention of any pair of dynamic
464caller/callee must match, or the behavior of the program is undefined. The
465following calling conventions are supported by LLVM, and more may be added in
466the future:</p>
467
468<dl>
469 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
470
471 <dd>This calling convention (the default if no other calling convention is
472 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]473 supports varargs function calls and tolerates some mismatch in the declared
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]474 prototype and implemented declaration of the function (as does normal C).
475 </dd>
476
Chris Lattner95ff1952006-05-19 21:15:36 +0000[diff] [blame]477 <dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
478
479 <dd>This calling convention matches the target C calling conventions, except
480 that functions with this convention are required to take a pointer as their
481 first argument, and the return type of the function must be void. This is
482 used for C functions that return aggregates by-value. In this case, the
483 function has been transformed to take a pointer to the struct as the first
484 argument to the function. For targets where the ABI specifies specific
485 behavior for structure-return calls, the calling convention can be used to
486 distinguish between struct return functions and other functions that take a
487 pointer to a struct as the first argument.
488 </dd>
489
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]490 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
491
492 <dd>This calling convention attempts to make calls as fast as possible
493 (e.g. by passing things in registers). This calling convention allows the
494 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]495 without having to conform to an externally specified ABI. Implementations of
496 this convention should allow arbitrary tail call optimization to be supported.
497 This calling convention does not support varargs and requires the prototype of
498 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]499 </dd>
500
501 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
502
503 <dd>This calling convention attempts to make code in the caller as efficient
504 as possible under the assumption that the call is not commonly executed. As
505 such, these calls often preserve all registers so that the call does not break
506 any live ranges in the caller side. This calling convention does not support
507 varargs and requires the prototype of all callees to exactly match the
508 prototype of the function definition.
509 </dd>
510
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]511 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]512
513 <dd>Any calling convention may be specified by number, allowing
514 target-specific calling conventions to be used. Target specific calling
515 conventions start at 64.
516 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]517</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]518
519<p>More calling conventions can be added/defined on an as-needed basis, to
520support pascal conventions or any other well-known target-independent
521convention.</p>
522
523</div>
524
525<!-- ======================================================================= -->
526<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]527 <a name="globalvars">Global Variables</a>
528</div>
529
530<div class="doc_text">
531
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]532<p>Global variables define regions of memory allocated at compilation time
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]533instead of run-time. Global variables may optionally be initialized, may have
534an explicit section to be placed in, and may
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]535have an optional explicit alignment specified. A
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]536variable may be defined as a global "constant," which indicates that the
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]537contents of the variable will <b>never</b> be modified (enabling better
538optimization, allowing the global data to be placed in the read-only section of
539an executable, etc). Note that variables that need runtime initialization
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]540cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]541
542<p>
543LLVM explicitly allows <em>declarations</em> of global variables to be marked
544constant, even if the final definition of the global is not. This capability
545can be used to enable slightly better optimization of the program, but requires
546the language definition to guarantee that optimizations based on the
547'constantness' are valid for the translation units that do not include the
548definition.
549</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]550
551<p>As SSA values, global variables define pointer values that are in
552scope (i.e. they dominate) all basic blocks in the program. Global
553variables always define a pointer to their "content" type because they
554describe a region of memory, and all memory objects in LLVM are
555accessed through pointers.</p>
556
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]557<p>LLVM allows an explicit section to be specified for globals. If the target
558supports it, it will emit globals to the section specified.</p>
559
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]560<p>An explicit alignment may be specified for a global. If not present, or if
561the alignment is set to zero, the alignment of the global is set by the target
562to whatever it feels convenient. If an explicit alignment is specified, the
563global is forced to have at least that much alignment. All alignments must be
564a power of 2.</p>
565
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]566</div>
567
568
569<!-- ======================================================================= -->
570<div class="doc_subsection">
571 <a name="functionstructure">Functions</a>
572</div>
573
574<div class="doc_text">
575
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]576<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
577type</a>, an optional <a href="#callingconv">calling convention</a>, a return
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]578type, a function name, a (possibly empty) argument list, an optional section,
579an optional alignment, an opening curly brace,
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]580a list of basic blocks, and a closing curly brace. LLVM function declarations
581are defined with the "<tt>declare</tt>" keyword, an optional <a
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]582href="#callingconv">calling convention</a>, a return type, a function name,
583a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]584
585<p>A function definition contains a list of basic blocks, forming the CFG for
586the function. Each basic block may optionally start with a label (giving the
587basic block a symbol table entry), contains a list of instructions, and ends
588with a <a href="#terminators">terminator</a> instruction (such as a branch or
589function return).</p>
590
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]591<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]592executed on entrance to the function, and it is not allowed to have predecessor
593basic blocks (i.e. there can not be any branches to the entry block of a
594function). Because the block can have no predecessors, it also cannot have any
595<a href="#i_phi">PHI nodes</a>.</p>
596
597<p>LLVM functions are identified by their name and type signature. Hence, two
598functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]599considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]600appropriately.</p>
601
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]602<p>LLVM allows an explicit section to be specified for functions. If the target
603supports it, it will emit functions to the section specified.</p>
604
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]605<p>An explicit alignment may be specified for a function. If not present, or if
606the alignment is set to zero, the alignment of the function is set by the target
607to whatever it feels convenient. If an explicit alignment is specified, the
608function is forced to have at least that much alignment. All alignments must be
609a power of 2.</p>
610
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]611</div>
612
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]613<!-- ======================================================================= -->
614<div class="doc_subsection">
Chris Lattner93564892006-04-08 04:40:53 +0000[diff] [blame]615 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]616</div>
617
618<div class="doc_text">
619<p>
620Modules may contain "module-level inline asm" blocks, which corresponds to the
621GCC "file scope inline asm" blocks. These blocks are internally concatenated by
622LLVM and treated as a single unit, but may be separated in the .ll file if
623desired. The syntax is very simple:
624</p>
625
626<div class="doc_code"><pre>
Chris Lattnera1280ad2006-01-24 00:37:20 +0000[diff] [blame]627 module asm "inline asm code goes here"
628 module asm "more can go here"
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]629</pre></div>
630
631<p>The strings can contain any character by escaping non-printable characters.
632 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
633 for the number.
634</p>
635
636<p>
637 The inline asm code is simply printed to the machine code .s file when
638 assembly code is generated.
639</p>
640</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]641
642
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]643<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]644<div class="doc_section"> <a name="typesystem">Type System</a> </div>
645<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]646
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]647<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]648
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]649<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]650intermediate representation. Being typed enables a number of
651optimizations to be performed on the IR directly, without having to do
652extra analyses on the side before the transformation. A strong type
653system makes it easier to read the generated code and enables novel
654analyses and transformations that are not feasible to perform on normal
655three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]656
657</div>
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_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]661<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]662<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]663system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]664
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]665<table class="layout">
666 <tr class="layout">
667 <td class="left">
668 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]669 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]670 <tr><th>Type</th><th>Description</th></tr>
671 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]672 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
673 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
674 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
675 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
676 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]677 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]678 </tbody>
679 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]680 </td>
681 <td class="right">
682 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]683 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]684 <tr><th>Type</th><th>Description</th></tr>
685 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]686 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
687 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
688 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
689 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
690 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]691 </tbody>
692 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]693 </td>
694 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]695</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]696</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]697
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]698<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]699<div class="doc_subsubsection"> <a name="t_classifications">Type
700Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]701<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]702<p>These different primitive types fall into a few useful
703classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]704
705<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]706 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]707 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]708 <tr>
709 <td><a name="t_signed">signed</a></td>
710 <td><tt>sbyte, short, int, long, float, double</tt></td>
711 </tr>
712 <tr>
713 <td><a name="t_unsigned">unsigned</a></td>
714 <td><tt>ubyte, ushort, uint, ulong</tt></td>
715 </tr>
716 <tr>
717 <td><a name="t_integer">integer</a></td>
718 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
719 </tr>
720 <tr>
721 <td><a name="t_integral">integral</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]722 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
723 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]724 </tr>
725 <tr>
726 <td><a name="t_floating">floating point</a></td>
727 <td><tt>float, double</tt></td>
728 </tr>
729 <tr>
730 <td><a name="t_firstclass">first class</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]731 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
732 float, double, <a href="#t_pointer">pointer</a>,
733 <a href="#t_packed">packed</a></tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]734 </tr>
735 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]736</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]737
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]738<p>The <a href="#t_firstclass">first class</a> types are perhaps the
739most important. Values of these types are the only ones which can be
740produced by instructions, passed as arguments, or used as operands to
741instructions. This means that all structures and arrays must be
742manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]743</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]744
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]745<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]746<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]747
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]748<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]749
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]750<p>The real power in LLVM comes from the derived types in the system.
751This is what allows a programmer to represent arrays, functions,
752pointers, and other useful types. Note that these derived types may be
753recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]754
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]755</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]756
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]757<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]758<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]759
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]760<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]761
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]762<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]763
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]764<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]765sequentially in memory. The array type requires a size (number of
766elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]767
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]768<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]769
770<pre>
771 [&lt;# elements&gt; x &lt;elementtype&gt;]
772</pre>
773
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]774<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]775be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]776
Chris Lattner590645f2002-04-14 06:13:44 +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>[40 x int ]</tt><br/>
782 <tt>[41 x int ]</tt><br/>
783 <tt>[40 x uint]</tt><br/>
784 </td>
785 <td class="left">
786 Array of 40 integer values.<br/>
787 Array of 41 integer values.<br/>
788 Array of 40 unsigned integer values.<br/>
789 </td>
790 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]791</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]792<p>Here are some examples of multidimensional arrays:</p>
793<table class="layout">
794 <tr class="layout">
795 <td class="left">
796 <tt>[3 x [4 x int]]</tt><br/>
797 <tt>[12 x [10 x float]]</tt><br/>
798 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
799 </td>
800 <td class="left">
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]801 3x4 array of integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]802 12x10 array of single precision floating point values.<br/>
803 2x3x4 array of unsigned integer values.<br/>
804 </td>
805 </tr>
806</table>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]807
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]808<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
809length array. Normally, accesses past the end of an array are undefined in
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]810LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
811As a special case, however, zero length arrays are recognized to be variable
812length. This allows implementation of 'pascal style arrays' with the LLVM
813type "{ int, [0 x float]}", for example.</p>
814
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]815</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]816
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]817<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]818<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]819<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]820<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]821<p>The function type can be thought of as a function signature. It
822consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]823Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]824(which are structures of pointers to functions), for indirect function
825calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]826<p>
827The return type of a function type cannot be an aggregate type.
828</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]829<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]830<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]831<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]832specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]833which indicates that the function takes a variable number of arguments.
834Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]835 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]836<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]837<table class="layout">
838 <tr class="layout">
839 <td class="left">
840 <tt>int (int)</tt> <br/>
841 <tt>float (int, int *) *</tt><br/>
842 <tt>int (sbyte *, ...)</tt><br/>
843 </td>
844 <td class="left">
845 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
846 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]847 <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]848 returning <tt>float</tt>.<br/>
849 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
850 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
851 the signature for <tt>printf</tt> in LLVM.<br/>
852 </td>
853 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]854</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]855
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]856</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]857<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]858<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]859<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]860<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]861<p>The structure type is used to represent a collection of data members
862together in memory. The packing of the field types is defined to match
863the ABI of the underlying processor. The elements of a structure may
864be any type that has a size.</p>
865<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
866and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
867field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
868instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]869<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]870<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]871<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]872<table class="layout">
873 <tr class="layout">
874 <td class="left">
875 <tt>{ int, int, int }</tt><br/>
876 <tt>{ float, int (int) * }</tt><br/>
877 </td>
878 <td class="left">
879 a triple of three <tt>int</tt> values<br/>
880 A pair, where the first element is a <tt>float</tt> and the second element
881 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
882 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
883 </td>
884 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]885</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]886</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]887
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]888<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]889<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]890<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]891<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]892<p>As in many languages, the pointer type represents a pointer or
893reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]894<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]895<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]896<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]897<table class="layout">
898 <tr class="layout">
899 <td class="left">
900 <tt>[4x int]*</tt><br/>
901 <tt>int (int *) *</tt><br/>
902 </td>
903 <td class="left">
904 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
905 four <tt>int</tt> values<br/>
906 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattner16fb0032005-02-19 02:22:14 +0000[diff] [blame]907 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]908 <tt>int</tt>.<br/>
909 </td>
910 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]911</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]912</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]913
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]914<!-- _______________________________________________________________________ -->
915<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]916<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]917
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]918<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]919
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]920<p>A packed type is a simple derived type that represents a vector
921of elements. Packed types are used when multiple primitive data
922are operated in parallel using a single instruction (SIMD).
923A packed type requires a size (number of
Chris Lattner330ce692005-11-10 01:44:22 +0000[diff] [blame]924elements) and an underlying primitive data type. Vectors must have a power
925of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]926considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]927
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]928<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]929
930<pre>
931 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
932</pre>
933
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]934<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]935be any integral or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]936
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]937<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]938
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]939<table class="layout">
940 <tr class="layout">
941 <td class="left">
942 <tt>&lt;4 x int&gt;</tt><br/>
943 <tt>&lt;8 x float&gt;</tt><br/>
944 <tt>&lt;2 x uint&gt;</tt><br/>
945 </td>
946 <td class="left">
947 Packed vector of 4 integer values.<br/>
948 Packed vector of 8 floating-point values.<br/>
949 Packed vector of 2 unsigned integer values.<br/>
950 </td>
951 </tr>
952</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]953</div>
954
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]955<!-- _______________________________________________________________________ -->
956<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
957<div class="doc_text">
958
959<h5>Overview:</h5>
960
961<p>Opaque types are used to represent unknown types in the system. This
962corresponds (for example) to the C notion of a foward declared structure type.
963In LLVM, opaque types can eventually be resolved to any type (not just a
964structure type).</p>
965
966<h5>Syntax:</h5>
967
968<pre>
969 opaque
970</pre>
971
972<h5>Examples:</h5>
973
974<table class="layout">
975 <tr class="layout">
976 <td class="left">
977 <tt>opaque</tt>
978 </td>
979 <td class="left">
980 An opaque type.<br/>
981 </td>
982 </tr>
983</table>
984</div>
985
986
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]987<!-- *********************************************************************** -->
988<div class="doc_section"> <a name="constants">Constants</a> </div>
989<!-- *********************************************************************** -->
990
991<div class="doc_text">
992
993<p>LLVM has several different basic types of constants. This section describes
994them all and their syntax.</p>
995
996</div>
997
998<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]999<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1000
1001<div class="doc_text">
1002
1003<dl>
1004 <dt><b>Boolean constants</b></dt>
1005
1006 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1007 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
1008 </dd>
1009
1010 <dt><b>Integer constants</b></dt>
1011
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1012 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1013 href="#t_integer">integer</a> type. Negative numbers may be used with signed
1014 integer types.
1015 </dd>
1016
1017 <dt><b>Floating point constants</b></dt>
1018
1019 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1020 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1021 notation (see below). Floating point constants must have a <a
1022 href="#t_floating">floating point</a> type. </dd>
1023
1024 <dt><b>Null pointer constants</b></dt>
1025
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1026 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1027 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1028
1029</dl>
1030
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1031<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1032of floating point constants. For example, the form '<tt>double
10330x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
10344.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1035(and the only time that they are generated by the disassembler) is when a
1036floating point constant must be emitted but it cannot be represented as a
1037decimal floating point number. For example, NaN's, infinities, and other
1038special values are represented in their IEEE hexadecimal format so that
1039assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1040
1041</div>
1042
1043<!-- ======================================================================= -->
1044<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1045</div>
1046
1047<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1048<p>Aggregate constants arise from aggregation of simple constants
1049and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1050
1051<dl>
1052 <dt><b>Structure constants</b></dt>
1053
1054 <dd>Structure constants are represented with notation similar to structure
1055 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1056 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
1057 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
1058 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1059 types of elements must match those specified by the type.
1060 </dd>
1061
1062 <dt><b>Array constants</b></dt>
1063
1064 <dd>Array constants are represented with notation similar to array type
1065 definitions (a comma separated list of elements, surrounded by square brackets
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1066 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1067 constants must have <a href="#t_array">array type</a>, and the number and
1068 types of elements must match those specified by the type.
1069 </dd>
1070
1071 <dt><b>Packed constants</b></dt>
1072
1073 <dd>Packed constants are represented with notation similar to packed type
1074 definitions (a comma separated list of elements, surrounded by
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1075 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]1076 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
1077 href="#t_packed">packed type</a>, and the number and types of elements must
1078 match those specified by the type.
1079 </dd>
1080
1081 <dt><b>Zero initialization</b></dt>
1082
1083 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1084 value to zero of <em>any</em> type, including scalar and aggregate types.
1085 This is often used to avoid having to print large zero initializers (e.g. for
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1086 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1087 initializers.
1088 </dd>
1089</dl>
1090
1091</div>
1092
1093<!-- ======================================================================= -->
1094<div class="doc_subsection">
1095 <a name="globalconstants">Global Variable and Function Addresses</a>
1096</div>
1097
1098<div class="doc_text">
1099
1100<p>The addresses of <a href="#globalvars">global variables</a> and <a
1101href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1102constants. These constants are explicitly referenced when the <a
1103href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1104href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1105file:</p>
1106
1107<pre>
1108 %X = global int 17
1109 %Y = global int 42
1110 %Z = global [2 x int*] [ int* %X, int* %Y ]
1111</pre>
1112
1113</div>
1114
1115<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1116<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1117<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1118 <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]1119 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1120 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1121
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1122 <p>Undefined values indicate to the compiler that the program is well defined
1123 no matter what value is used, giving the compiler more freedom to optimize.
1124 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1125</div>
1126
1127<!-- ======================================================================= -->
1128<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1129</div>
1130
1131<div class="doc_text">
1132
1133<p>Constant expressions are used to allow expressions involving other constants
1134to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1135href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1136that does not have side effects (e.g. load and call are not supported). The
1137following is the syntax for constant expressions:</p>
1138
1139<dl>
1140 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1141
1142 <dd>Cast a constant to another type.</dd>
1143
1144 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1145
1146 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1147 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1148 instruction, the index list may have zero or more indexes, which are required
1149 to make sense for the type of "CSTPTR".</dd>
1150
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1151 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1152
1153 <dd>Perform the <a href="#i_select">select operation</a> on
1154 constants.
1155
1156 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1157
1158 <dd>Perform the <a href="#i_extractelement">extractelement
1159 operation</a> on constants.
1160
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1161 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1162
1163 <dd>Perform the <a href="#i_insertelement">insertelement
1164 operation</a> on constants.
1165
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1166
1167 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1168
1169 <dd>Perform the <a href="#i_shufflevector">shufflevector
1170 operation</a> on constants.
1171
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1172 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1173
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1174 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1175 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1176 binary</a> operations. The constraints on operands are the same as those for
1177 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1178 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1179</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1180</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1181
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1182<!-- *********************************************************************** -->
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1183<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1184<!-- *********************************************************************** -->
1185
1186<!-- ======================================================================= -->
1187<div class="doc_subsection">
1188<a name="inlineasm">Inline Assembler Expressions</a>
1189</div>
1190
1191<div class="doc_text">
1192
1193<p>
1194LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1195Module-Level Inline Assembly</a>) through the use of a special value. This
1196value represents the inline assembler as a string (containing the instructions
1197to emit), a list of operand constraints (stored as a string), and a flag that
1198indicates whether or not the inline asm expression has side effects. An example
1199inline assembler expression is:
1200</p>
1201
1202<pre>
1203 int(int) asm "bswap $0", "=r,r"
1204</pre>
1205
1206<p>
1207Inline assembler expressions may <b>only</b> be used as the callee operand of
1208a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1209</p>
1210
1211<pre>
1212 %X = call int asm "<a href="#i_bswap">bswap</a> $0", "=r,r"(int %Y)
1213</pre>
1214
1215<p>
1216Inline asms with side effects not visible in the constraint list must be marked
1217as having side effects. This is done through the use of the
1218'<tt>sideeffect</tt>' keyword, like so:
1219</p>
1220
1221<pre>
1222 call void asm sideeffect "eieio", ""()
1223</pre>
1224
1225<p>TODO: The format of the asm and constraints string still need to be
1226documented here. Constraints on what can be done (e.g. duplication, moving, etc
1227need to be documented).
1228</p>
1229
1230</div>
1231
1232<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1233<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1234<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1235
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1236<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1237
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1238<p>The LLVM instruction set consists of several different
1239classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1240instructions</a>, <a href="#binaryops">binary instructions</a>,
1241<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1242 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1243instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1244
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1245</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1246
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1247<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1248<div class="doc_subsection"> <a name="terminators">Terminator
1249Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1250
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1251<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1252
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1253<p>As mentioned <a href="#functionstructure">previously</a>, every
1254basic block in a program ends with a "Terminator" instruction, which
1255indicates which block should be executed after the current block is
1256finished. These terminator instructions typically yield a '<tt>void</tt>'
1257value: they produce control flow, not values (the one exception being
1258the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1259<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1260 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1261instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1262the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1263 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1264 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1265
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1266</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1267
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1268<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1269<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1270Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1271<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1272<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1273<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]1274 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1275</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1276<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1277<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1278value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1279<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1280returns a value and then causes control flow, and one that just causes
1281control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1282<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1283<p>The '<tt>ret</tt>' instruction may return any '<a
1284 href="#t_firstclass">first class</a>' type. Notice that a function is
1285not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1286instruction inside of the function that returns a value that does not
1287match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1288<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1289<p>When the '<tt>ret</tt>' instruction is executed, control flow
1290returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1291 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1292the instruction after the call. If the caller was an "<a
1293 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1294at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1295returns a value, that value shall set the call or invoke instruction's
1296return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1297<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1298<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1299 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1300</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1301</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1302<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1303<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1304<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1305<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1306<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]1307</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1308<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1309<p>The '<tt>br</tt>' instruction is used to cause control flow to
1310transfer to a different basic block in the current function. There are
1311two forms of this instruction, corresponding to a conditional branch
1312and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1313<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1314<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1315single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1316unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1317value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1318<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1319<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1320argument is evaluated. If the value is <tt>true</tt>, control flows
1321to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1322control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1323<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1324<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
1325 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]1326</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1327<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1328<div class="doc_subsubsection">
1329 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1330</div>
1331
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1332<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1333<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1334
1335<pre>
1336 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1337</pre>
1338
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1339<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1340
1341<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1342several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1343instruction, allowing a branch to occur to one of many possible
1344destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1345
1346
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1347<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1348
1349<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1350comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1351an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1352table is not allowed to contain duplicate constant entries.</p>
1353
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1354<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1355
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1356<p>The <tt>switch</tt> instruction specifies a table of values and
1357destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1358table is searched for the given value. If the value is found, control flow is
1359transfered to the corresponding destination; otherwise, control flow is
1360transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1361
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1362<h5>Implementation:</h5>
1363
1364<p>Depending on properties of the target machine and the particular
1365<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1366ways. For example, it could be generated as a series of chained conditional
1367branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1368
1369<h5>Example:</h5>
1370
1371<pre>
1372 <i>; Emulate a conditional br instruction</i>
1373 %Val = <a href="#i_cast">cast</a> bool %value to int
1374 switch int %Val, label %truedest [int 0, label %falsedest ]
1375
1376 <i>; Emulate an unconditional br instruction</i>
1377 switch uint 0, label %dest [ ]
1378
1379 <i>; Implement a jump table:</i>
1380 switch uint %val, label %otherwise [ uint 0, label %onzero
1381 uint 1, label %onone
1382 uint 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1383</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1384</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1385
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1386<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1387<div class="doc_subsubsection">
1388 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1389</div>
1390
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1391<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1392
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1393<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1394
1395<pre>
1396 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
Chris Lattner6b7a0082006-05-14 18:23:06 +0000[diff] [blame]1397 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1398</pre>
1399
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1400<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1401
1402<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1403function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1404'<tt>normal</tt>' label or the
1405'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1406"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1407"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1408href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1409continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1410
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1411<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1412
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1413<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1414
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1415<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1416 <li>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1417 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1418 convention</a> the call should use. If none is specified, the call defaults
1419 to using C calling conventions.
1420 </li>
1421 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1422 function value being invoked. In most cases, this is a direct function
1423 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1424 an arbitrary pointer to function value.
1425 </li>
1426
1427 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1428 function to be invoked. </li>
1429
1430 <li>'<tt>function args</tt>': argument list whose types match the function
1431 signature argument types. If the function signature indicates the function
1432 accepts a variable number of arguments, the extra arguments can be
1433 specified. </li>
1434
1435 <li>'<tt>normal label</tt>': the label reached when the called function
1436 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1437
1438 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1439 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1440
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1441</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1442
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1443<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1444
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1445<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1446href="#i_call">call</a></tt>' instruction in most regards. The primary
1447difference is that it establishes an association with a label, which is used by
1448the runtime library to unwind the stack.</p>
1449
1450<p>This instruction is used in languages with destructors to ensure that proper
1451cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1452exception. Additionally, this is important for implementation of
1453'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1454
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1455<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1456<pre>
1457 %retval = invoke int %Test(int 15) to label %Continue
Chris Lattner6b7a0082006-05-14 18:23:06 +0000[diff] [blame]1458 unwind label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1459 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
Chris Lattner6b7a0082006-05-14 18:23:06 +0000[diff] [blame]1460 unwind label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1461</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1462</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1463
1464
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1465<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1466
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1467<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1468Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1469
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1470<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1471
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1472<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1473<pre>
1474 unwind
1475</pre>
1476
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1477<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1478
1479<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1480at the first callee in the dynamic call stack which used an <a
1481href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1482primarily used to implement exception handling.</p>
1483
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1484<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1485
1486<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1487immediately halt. The dynamic call stack is then searched for the first <a
1488href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1489execution continues at the "exceptional" destination block specified by the
1490<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1491dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1492</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1493
1494<!-- _______________________________________________________________________ -->
1495
1496<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1497Instruction</a> </div>
1498
1499<div class="doc_text">
1500
1501<h5>Syntax:</h5>
1502<pre>
1503 unreachable
1504</pre>
1505
1506<h5>Overview:</h5>
1507
1508<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1509instruction is used to inform the optimizer that a particular portion of the
1510code is not reachable. This can be used to indicate that the code after a
1511no-return function cannot be reached, and other facts.</p>
1512
1513<h5>Semantics:</h5>
1514
1515<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1516</div>
1517
1518
1519
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1520<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1521<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1522<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1523<p>Binary operators are used to do most of the computation in a
1524program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1525produce a single value. The operands might represent
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1526multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1527The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1528necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1529<p>There are several different binary operators:</p>
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_subsubsection"> <a name="i_add">'<tt>add</tt>'
1533Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1534<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1535<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1536<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]1537</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1538<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1539<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1540<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1541<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1542 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1543 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1544Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1545<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1546<p>The value produced is the integer or floating point sum of the two
1547operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1548<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1549<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]1550</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1551</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1552<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1553<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1554Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1555<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1556<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1557<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]1558</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1559<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1560<p>The '<tt>sub</tt>' instruction returns the difference of its two
1561operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1562<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1563instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1564<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1565<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1566 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1567values.
1568This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1569Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1570<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1571<p>The value produced is the integer or floating point difference of
1572the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1573<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1574<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]1575 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1576</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1577</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1578<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1579<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1580Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1581<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1582<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1583<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]1584</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1585<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1586<p>The '<tt>mul</tt>' instruction returns the product of its two
1587operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1588<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1589<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1590 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1591values.
1592This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1593Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1594<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1595<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1596two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1597<p>There is no signed vs unsigned multiplication. The appropriate
1598action is taken based on the type of the operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1599<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1600<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]1601</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1602</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1603<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1604<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1605Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1606<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1607<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1608<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1609</pre>
1610<h5>Overview:</h5>
1611<p>The '<tt>div</tt>' instruction returns the quotient of its two
1612operands.</p>
1613<h5>Arguments:</h5>
1614<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1615 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1616values.
1617This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1618Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1619<h5>Semantics:</h5>
1620<p>The value produced is the integer or floating point quotient of the
1621two operands.</p>
1622<h5>Example:</h5>
1623<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1624</pre>
1625</div>
1626<!-- _______________________________________________________________________ -->
1627<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1628Instruction</a> </div>
1629<div class="doc_text">
1630<h5>Syntax:</h5>
1631<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1632</pre>
1633<h5>Overview:</h5>
1634<p>The '<tt>rem</tt>' instruction returns the remainder from the
1635division of its two operands.</p>
1636<h5>Arguments:</h5>
1637<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1638 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1639values.
1640This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1641Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1642<h5>Semantics:</h5>
1643<p>This returns the <i>remainder</i> of a division (where the result
1644has the same sign as the divisor), not the <i>modulus</i> (where the
1645result has the same sign as the dividend) of a value. For more
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1646information about the difference, see <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1647 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1648Math Forum</a>.</p>
1649<h5>Example:</h5>
1650<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1651</pre>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]1652
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1653</div>
1654<!-- _______________________________________________________________________ -->
1655<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1656Instructions</a> </div>
1657<div class="doc_text">
1658<h5>Syntax:</h5>
1659<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]1660 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1661 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1662 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1663 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1664 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1665</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1666<h5>Overview:</h5>
1667<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1668value based on a comparison of their two operands.</p>
1669<h5>Arguments:</h5>
1670<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1671be of <a href="#t_firstclass">first class</a> type (it is not possible
1672to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1673or '<tt>void</tt>' values, etc...). Both arguments must have identical
1674types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1675<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1676<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1677value if both operands are equal.<br>
1678The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1679value if both operands are unequal.<br>
1680The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1681value if the first operand is less than the second operand.<br>
1682The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1683value if the first operand is greater than the second operand.<br>
1684The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1685value if the first operand is less than or equal to the second operand.<br>
1686The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1687value if the first operand is greater than or equal to the second
1688operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1689<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1690<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1691 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1692 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1693 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1694 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1695 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1696</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1697</div>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]1698
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1699<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1700<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1701Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1702<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1703<p>Bitwise binary operators are used to do various forms of
1704bit-twiddling in a program. They are generally very efficient
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1705instructions and can commonly be strength reduced from other
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1706instructions. They require two operands, execute an operation on them,
1707and produce a single value. The resulting value of the bitwise binary
1708operators is always the same type as its first operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1709</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1710<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1711<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1712Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1713<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1714<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1715<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]1716</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1717<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1718<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1719its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1720<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1721<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1722 href="#t_integral">integral</a> values. Both arguments must have
1723identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1724<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1725<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1726<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1727<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1728<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1729 <tbody>
1730 <tr>
1731 <td>In0</td>
1732 <td>In1</td>
1733 <td>Out</td>
1734 </tr>
1735 <tr>
1736 <td>0</td>
1737 <td>0</td>
1738 <td>0</td>
1739 </tr>
1740 <tr>
1741 <td>0</td>
1742 <td>1</td>
1743 <td>0</td>
1744 </tr>
1745 <tr>
1746 <td>1</td>
1747 <td>0</td>
1748 <td>0</td>
1749 </tr>
1750 <tr>
1751 <td>1</td>
1752 <td>1</td>
1753 <td>1</td>
1754 </tr>
1755 </tbody>
1756</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1757</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1758<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1759<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]1760 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1761 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1762</pre>
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_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1766<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1767<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1768<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]1769</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1770<h5>Overview:</h5>
1771<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1772or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1773<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1774<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1775 href="#t_integral">integral</a> values. Both arguments must have
1776identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1777<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1778<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1779<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1780<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1781<table border="1" cellspacing="0" cellpadding="4">
1782 <tbody>
1783 <tr>
1784 <td>In0</td>
1785 <td>In1</td>
1786 <td>Out</td>
1787 </tr>
1788 <tr>
1789 <td>0</td>
1790 <td>0</td>
1791 <td>0</td>
1792 </tr>
1793 <tr>
1794 <td>0</td>
1795 <td>1</td>
1796 <td>1</td>
1797 </tr>
1798 <tr>
1799 <td>1</td>
1800 <td>0</td>
1801 <td>1</td>
1802 </tr>
1803 <tr>
1804 <td>1</td>
1805 <td>1</td>
1806 <td>1</td>
1807 </tr>
1808 </tbody>
1809</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1810</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1811<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1812<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]1813 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1814 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
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_xor">'<tt>xor</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; = 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]1823</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1824<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1825<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1826or of its two operands. The <tt>xor</tt> is used to implement the
1827"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1828<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1829<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1830 href="#t_integral">integral</a> values. Both arguments must have
1831identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1832<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1833<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1834<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1835<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1836<table border="1" cellspacing="0" cellpadding="4">
1837 <tbody>
1838 <tr>
1839 <td>In0</td>
1840 <td>In1</td>
1841 <td>Out</td>
1842 </tr>
1843 <tr>
1844 <td>0</td>
1845 <td>0</td>
1846 <td>0</td>
1847 </tr>
1848 <tr>
1849 <td>0</td>
1850 <td>1</td>
1851 <td>1</td>
1852 </tr>
1853 <tr>
1854 <td>1</td>
1855 <td>0</td>
1856 <td>1</td>
1857 </tr>
1858 <tr>
1859 <td>1</td>
1860 <td>1</td>
1861 <td>0</td>
1862 </tr>
1863 </tbody>
1864</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1865</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1866<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1867<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1868<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]1869 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1870 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1871 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1872</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1873</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1874<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1875<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1876Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1877<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1878<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1879<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]1880</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1881<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1882<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1883the left a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1884<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1885<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1886 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1887type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1888<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1889<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]1890<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1891<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]1892 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1893 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1894</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1895</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1896<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1897<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1898Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1899<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1900<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1901<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]1902</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1903<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1904<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1905the right a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1906<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1907<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1908 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1909type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1910<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1911<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1912most significant bit is duplicated in the newly free'd bit positions.
1913If the first argument is unsigned, zero bits shall fill the empty
1914positions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1915<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1916<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]1917 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1918 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1919 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1920 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1921</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1922</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1923
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1924<!-- ======================================================================= -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]1925<div class="doc_subsection">
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]1926 <a name="vectorops">Vector Operations</a>
1927</div>
1928
1929<div class="doc_text">
1930
1931<p>LLVM supports several instructions to represent vector operations in a
1932target-independent manner. This instructions cover the element-access and
1933vector-specific operations needed to process vectors effectively. While LLVM
1934does directly support these vector operations, many sophisticated algorithms
1935will want to use target-specific intrinsics to take full advantage of a specific
1936target.</p>
1937
1938</div>
1939
1940<!-- _______________________________________________________________________ -->
1941<div class="doc_subsubsection">
1942 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
1943</div>
1944
1945<div class="doc_text">
1946
1947<h5>Syntax:</h5>
1948
1949<pre>
1950 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, uint &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
1951</pre>
1952
1953<h5>Overview:</h5>
1954
1955<p>
1956The '<tt>extractelement</tt>' instruction extracts a single scalar
1957element from a packed vector at a specified index.
1958</p>
1959
1960
1961<h5>Arguments:</h5>
1962
1963<p>
1964The first operand of an '<tt>extractelement</tt>' instruction is a
1965value of <a href="#t_packed">packed</a> type. The second operand is
1966an index indicating the position from which to extract the element.
1967The index may be a variable.</p>
1968
1969<h5>Semantics:</h5>
1970
1971<p>
1972The result is a scalar of the same type as the element type of
1973<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
1974<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
1975results are undefined.
1976</p>
1977
1978<h5>Example:</h5>
1979
1980<pre>
1981 %result = extractelement &lt;4 x int&gt; %vec, uint 0 <i>; yields int</i>
1982</pre>
1983</div>
1984
1985
1986<!-- _______________________________________________________________________ -->
1987<div class="doc_subsubsection">
1988 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
1989</div>
1990
1991<div class="doc_text">
1992
1993<h5>Syntax:</h5>
1994
1995<pre>
1996 &lt;result&gt; = insertelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, &lt;ty&gt; &lt;elt&gt, uint &lt;idx&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
1997</pre>
1998
1999<h5>Overview:</h5>
2000
2001<p>
2002The '<tt>insertelement</tt>' instruction inserts a scalar
2003element into a packed vector at a specified index.
2004</p>
2005
2006
2007<h5>Arguments:</h5>
2008
2009<p>
2010The first operand of an '<tt>insertelement</tt>' instruction is a
2011value of <a href="#t_packed">packed</a> type. The second operand is a
2012scalar value whose type must equal the element type of the first
2013operand. The third operand is an index indicating the position at
2014which to insert the value. The index may be a variable.</p>
2015
2016<h5>Semantics:</h5>
2017
2018<p>
2019The result is a packed vector of the same type as <tt>val</tt>. Its
2020element values are those of <tt>val</tt> except at position
2021<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2022exceeds the length of <tt>val</tt>, the results are undefined.
2023</p>
2024
2025<h5>Example:</h5>
2026
2027<pre>
2028 %result = insertelement &lt;4 x int&gt; %vec, int 1, uint 0 <i>; yields &lt;4 x int&gt;</i>
2029</pre>
2030</div>
2031
2032<!-- _______________________________________________________________________ -->
2033<div class="doc_subsubsection">
2034 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2035</div>
2036
2037<div class="doc_text">
2038
2039<h5>Syntax:</h5>
2040
2041<pre>
2042 &lt;result&gt; = shufflevector &lt;n x &lt;ty&gt;&gt; &lt;v1&gt;, &lt;n x &lt;ty&gt;&gt; &lt;v2&gt;, &lt;n x uint&gt; &lt;mask&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
2043</pre>
2044
2045<h5>Overview:</h5>
2046
2047<p>
2048The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2049from two input vectors, returning a vector of the same type.
2050</p>
2051
2052<h5>Arguments:</h5>
2053
2054<p>
2055The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2056with types that match each other and types that match the result of the
2057instruction. The third argument is a shuffle mask, which has the same number
2058of elements as the other vector type, but whose element type is always 'uint'.
2059</p>
2060
2061<p>
2062The shuffle mask operand is required to be a constant vector with either
2063constant integer or undef values.
2064</p>
2065
2066<h5>Semantics:</h5>
2067
2068<p>
2069The elements of the two input vectors are numbered from left to right across
2070both of the vectors. The shuffle mask operand specifies, for each element of
2071the result vector, which element of the two input registers the result element
2072gets. The element selector may be undef (meaning "don't care") and the second
2073operand may be undef if performing a shuffle from only one vector.
2074</p>
2075
2076<h5>Example:</h5>
2077
2078<pre>
2079 %result = shufflevector &lt;4 x int&gt; %v1, &lt;4 x int&gt; %v2,
2080 &lt;4 x uint&gt; &lt;uint 0, uint 4, uint 1, uint 5&gt; <i>; yields &lt;4 x int&gt;</i>
2081 %result = shufflevector &lt;4 x int&gt; %v1, &lt;4 x int&gt; undef,
2082 &lt;4 x uint&gt; &lt;uint 0, uint 1, uint 2, uint 3&gt; <i>; yields &lt;4 x int&gt;</i> - Identity shuffle.
2083</pre>
2084</div>
2085
Tanya Lattnerb138bbe2006-04-14 19:24:33 +0000[diff] [blame]2086
2087<!-- _______________________________________________________________________ -->
2088<div class="doc_subsubsection"> <a name="i_vsetint">'<tt>vsetint</tt>'
2089Instruction</a> </div>
2090<div class="doc_text">
2091<h5>Syntax:</h5>
2092<pre>&lt;result&gt; = vsetint &lt;op&gt;, &lt;n x &lt;ty&gt;&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields &lt;n x bool&gt;</i>
2093</pre>
2094
2095<h5>Overview:</h5>
2096
2097<p>The '<tt>vsetint</tt>' instruction takes two integer vectors and
2098returns a vector of boolean values representing, at each position, the
2099result of the comparison between the values at that position in the
2100two operands.</p>
2101
2102<h5>Arguments:</h5>
2103
2104<p>The arguments to a '<tt>vsetint</tt>' instruction are a comparison
2105operation and two value arguments. The value arguments must be of <a
2106href="#t_integral">integral</a> <a href="#t_packed">packed</a> type,
2107and they must have identical types. The operation argument must be
2108one of <tt>eq</tt>, <tt>ne</tt>, <tt>slt</tt>, <tt>sgt</tt>,
2109<tt>sle</tt>, <tt>sge</tt>, <tt>ult</tt>, <tt>ugt</tt>, <tt>ule</tt>,
2110<tt>uge</tt>, <tt>true</tt>, and <tt>false</tt>. The result is a
2111packed <tt>bool</tt> value with the same length as each operand.</p>
2112
2113<h5>Semantics:</h5>
2114
2115<p>The following table shows the semantics of '<tt>vsetint</tt>'. For
2116each position of the result, the comparison is done on the
2117corresponding positions of the two value arguments. Note that the
2118signedness of the comparison depends on the comparison opcode and
2119<i>not</i> on the signedness of the value operands. E.g., <tt>vsetint
2120slt <4 x unsigned> %x, %y</tt> does an elementwise <i>signed</i>
2121comparison of <tt>%x</tt> and <tt>%y</tt>.</p>
2122
2123<table border="1" cellspacing="0" cellpadding="4">
2124 <tbody>
2125 <tr><th>Operation</th><th>Result is true iff</th><th>Comparison is</th></tr>
2126 <tr><td><tt>eq</tt></td><td>var1 == var2</td><td>--</td></tr>
2127 <tr><td><tt>ne</tt></td><td>var1 != var2</td><td>--</td></tr>
2128 <tr><td><tt>slt</tt></td><td>var1 &lt; var2</td><td>signed</td></tr>
2129 <tr><td><tt>sgt</tt></td><td>var1 &gt; var2</td><td>signed</td></tr>
2130 <tr><td><tt>sle</tt></td><td>var1 &lt;= var2</td><td>signed</td></tr>
2131 <tr><td><tt>sge</tt></td><td>var1 &gt;= var2</td><td>signed</td></tr>
2132 <tr><td><tt>ult</tt></td><td>var1 &lt; var2</td><td>unsigned</td></tr>
2133 <tr><td><tt>ugt</tt></td><td>var1 &gt; var2</td><td>unsigned</td></tr>
2134 <tr><td><tt>ule</tt></td><td>var1 &lt;= var2</td><td>unsigned</td></tr>
2135 <tr><td><tt>uge</tt></td><td>var1 &gt;= var2</td><td>unsigned</td></tr>
2136 <tr><td><tt>true</tt></td><td>always</td><td>--</td></tr>
2137 <tr><td><tt>false</tt></td><td>never</td><td>--</td></tr>
2138 </tbody>
2139</table>
2140
2141<h5>Example:</h5>
2142<pre> &lt;result&gt; = vsetint eq &lt;2 x int&gt; &lt;int 0, int 1&gt;, &lt;int 1, int 0&gt; <i>; yields {&lt;2 x bool&gt;}:result = false, false</i>
2143 &lt;result&gt; = vsetint ne &lt;2 x int&gt; &lt;int 0, int 1&gt;, &lt;int 1, int 0&gt; <i>; yields {&lt;2 x bool&gt;}:result = true, true</i>
2144 &lt;result&gt; = vsetint slt &lt;2 x int&gt; &lt;int 0, int 1&gt;, &lt;int 1, int 0&gt; <i>; yields {&lt;2 x bool&gt;}:result = true, false</i>
2145 &lt;result&gt; = vsetint sgt &lt;2 x int&gt; &lt;int 0, int 1&gt;, &lt;int 1, int 0&gt; <i>; yields {&lt;2 x bool&gt;}:result = false, true</i>
2146 &lt;result&gt; = vsetint sle &lt;2 x int&gt; &lt;int 0, int 1&gt;, &lt;int 1, int 0&gt; <i>; yields {&lt;2 x bool&gt;}:result = true, false</i>
2147 &lt;result&gt; = vsetint sge &lt;2 x int&gt; &lt;int 0, int 1&gt;, &lt;int 1, int 0&gt; <i>; yields {&lt;2 x bool&gt;}:result = false, true</i>
2148</pre>
2149</div>
2150
2151<!-- _______________________________________________________________________ -->
2152<div class="doc_subsubsection"> <a name="i_vsetfp">'<tt>vsetfp</tt>'
2153Instruction</a> </div>
2154<div class="doc_text">
2155<h5>Syntax:</h5>
2156<pre>&lt;result&gt; = vsetfp &lt;op&gt;, &lt;n x &lt;ty&gt;&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields &lt;n x bool&gt;</i>
2157</pre>
2158
2159<h5>Overview:</h5>
2160
2161<p>The '<tt>vsetfp</tt>' instruction takes two floating point vector
2162arguments and returns a vector of boolean values representing, at each
2163position, the result of the comparison between the values at that
2164position in the two operands.</p>
2165
2166<h5>Arguments:</h5>
2167
2168<p>The arguments to a '<tt>vsetfp</tt>' instruction are a comparison
2169operation and two value arguments. The value arguments must be of <a
2170href="t_floating">floating point</a> <a href="#t_packed">packed</a>
2171type, and they must have identical types. The operation argument must
2172be one of <tt>eq</tt>, <tt>ne</tt>, <tt>lt</tt>, <tt>gt</tt>,
2173<tt>le</tt>, <tt>ge</tt>, <tt>oeq</tt>, <tt>one</tt>, <tt>olt</tt>,
2174<tt>ogt</tt>, <tt>ole</tt>, <tt>oge</tt>, <tt>ueq</tt>, <tt>une</tt>,
2175<tt>ult</tt>, <tt>ugt</tt>, <tt>ule</tt>, <tt>uge</tt>, <tt>o</tt>,
2176<tt>u</tt>, <tt>true</tt>, and <tt>false</tt>. The result is a packed
2177<tt>bool</tt> value with the same length as each operand.</p>
2178
2179<h5>Semantics:</h5>
2180
2181<p>The following table shows the semantics of '<tt>vsetfp</tt>' for
2182floating point types. If either operand is a floating point Not a
2183Number (NaN) value, the operation is unordered, and the value in the
2184first column below is produced at that position. Otherwise, the
2185operation is ordered, and the value in the second column is
2186produced.</p>
2187
2188<table border="1" cellspacing="0" cellpadding="4">
2189 <tbody>
2190 <tr><th>Operation</th><th>If unordered<th>Otherwise true iff</th></tr>
2191 <tr><td><tt>eq</tt></td><td>undefined</td><td>var1 == var2</td></tr>
2192 <tr><td><tt>ne</tt></td><td>undefined</td><td>var1 != var2</td></tr>
2193 <tr><td><tt>lt</tt></td><td>undefined</td><td>var1 &lt; var2</td></tr>
2194 <tr><td><tt>gt</tt></td><td>undefined</td><td>var1 &gt; var2</td></tr>
2195 <tr><td><tt>le</tt></td><td>undefined</td><td>var1 &lt;= var2</td></tr>
2196 <tr><td><tt>ge</tt></td><td>undefined</td><td>var1 &gt;= var2</td></tr>
2197 <tr><td><tt>oeq</tt></td><td>false</td><td>var1 == var2</td></tr>
2198 <tr><td><tt>one</tt></td><td>false</td><td>var1 != var2</td></tr>
2199 <tr><td><tt>olt</tt></td><td>false</td><td>var1 &lt; var2</td></tr>
2200 <tr><td><tt>ogt</tt></td><td>false</td><td>var1 &gt; var2</td></tr>
2201 <tr><td><tt>ole</tt></td><td>false</td><td>var1 &lt;= var2</td></tr>
2202 <tr><td><tt>oge</tt></td><td>false</td><td>var1 &gt;= var2</td></tr>
2203 <tr><td><tt>ueq</tt></td><td>true</td><td>var1 == var2</td></tr>
2204 <tr><td><tt>une</tt></td><td>true</td><td>var1 != var2</td></tr>
2205 <tr><td><tt>ult</tt></td><td>true</td><td>var1 &lt; var2</td></tr>
2206 <tr><td><tt>ugt</tt></td><td>true</td><td>var1 &gt; var2</td></tr>
2207 <tr><td><tt>ule</tt></td><td>true</td><td>var1 &lt;= var2</td></tr>
2208 <tr><td><tt>uge</tt></td><td>true</td><td>var1 &gt;= var2</td></tr>
2209 <tr><td><tt>o</tt></td><td>false</td><td>always</td></tr>
2210 <tr><td><tt>u</tt></td><td>true</td><td>never</td></tr>
2211 <tr><td><tt>true</tt></td><td>true</td><td>always</td></tr>
2212 <tr><td><tt>false</tt></td><td>false</td><td>never</td></tr>
2213 </tbody>
2214</table>
2215
2216<h5>Example:</h5>
2217<pre> &lt;result&gt; = vsetfp eq &lt;2 x float&gt; &lt;float 0.0, float 1.0&gt;, &lt;float 1.0, float 0.0&gt; <i>; yields {&lt;2 x bool&gt;}:result = false, false</i>
2218 &lt;result&gt; = vsetfp ne &lt;2 x float&gt; &lt;float 0.0, float 1.0&gt;, &lt;float 1.0, float 0.0&gt; <i>; yields {&lt;2 x bool&gt;}:result = true, true</i>
2219 &lt;result&gt; = vsetfp lt &lt;2 x float&gt; &lt;float 0.0, float 1.0&gt;, &lt;float 1.0, float 0.0&gt; <i>; yields {&lt;2 x bool&gt;}:result = true, false</i>
2220 &lt;result&gt; = vsetfp gt &lt;2 x float&gt; &lt;float 0.0, float 1.0&gt;, &lt;float 1.0, float 0.0&gt; <i>; yields {&lt;2 x bool&gt;}:result = false, true</i>
2221 &lt;result&gt; = vsetfp le &lt;2 x float&gt; &lt;float 0.0, float 1.0&gt;, &lt;float 1.0, float 0.0&gt; <i>; yields {&lt;2 x bool&gt;}:result = true, false</i>
2222 &lt;result&gt; = vsetfp ge &lt;2 x float&gt; &lt;float 0.0, float 1.0&gt;, &lt;float 1.0, float 0.0&gt; <i>; yields {&lt;2 x bool&gt;}:result = false, true</i>
2223</pre>
2224</div>
2225
2226<!-- _______________________________________________________________________ -->
2227<div class="doc_subsubsection">
2228 <a name="i_vselect">'<tt>vselect</tt>' Instruction</a>
2229</div>
2230
2231<div class="doc_text">
2232
2233<h5>Syntax:</h5>
2234
2235<pre>
2236 &lt;result&gt; = vselect &lt;n x bool&gt; &lt;cond&gt;, &lt;n x &lt;ty&gt;&gt; &lt;val1&gt;, &lt;n x &lt;ty&gt;&gt; &lt;val2&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
2237</pre>
2238
2239<h5>Overview:</h5>
2240
2241<p>
2242The '<tt>vselect</tt>' instruction chooses one value at each position
2243of a vector based on a condition.
2244</p>
2245
2246
2247<h5>Arguments:</h5>
2248
2249<p>
2250The '<tt>vselect</tt>' instruction requires a <a
2251href="#t_packed">packed</a> <tt>bool</tt> value indicating the
2252condition at each vector position, and two values of the same packed
2253type. All three operands must have the same length. The type of the
2254result is the same as the type of the two value operands.</p>
2255
2256<h5>Semantics:</h5>
2257
2258<p>
2259At each position where the <tt>bool</tt> vector is true, that position
2260of the result gets its value from the first value argument; otherwise,
2261it gets its value from the second value argument.
2262</p>
2263
2264<h5>Example:</h5>
2265
2266<pre>
2267 %X = vselect bool &lt;2 x bool&gt; &lt;bool true, bool false&gt;, &lt;2 x ubyte&gt; &lt;ubyte 17, ubyte 17&gt;,
2268 &lt;2 x ubyte&gt; &lt;ubyte 42, ubyte 42&gt; <i>; yields &lt;2 x ubyte&gt;:17, 42</i>
2269</pre>
2270</div>
2271
2272
2273
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2274<!-- ======================================================================= -->
2275<div class="doc_subsection">
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2276 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2277</div>
2278
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2279<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2280
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2281<p>A key design point of an SSA-based representation is how it
2282represents memory. In LLVM, no memory locations are in SSA form, which
2283makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2284allocate, and free memory in LLVM.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2285
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2286</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2287
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2288<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2289<div class="doc_subsubsection">
2290 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2291</div>
2292
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2293<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2294
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2295<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2296
2297<pre>
2298 &lt;result&gt; = malloc &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2299</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2300
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2301<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2302
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2303<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2304heap and returns a pointer to it.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2305
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2306<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2307
2308<p>The '<tt>malloc</tt>' instruction allocates
2309<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]2310bytes of memory from the operating system and returns a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2311appropriate type to the program. If "NumElements" is specified, it is the
2312number of elements allocated. If an alignment is specified, the value result
2313of the allocation is guaranteed to be aligned to at least that boundary. If
2314not specified, or if zero, the target can choose to align the allocation on any
2315convenient boundary.</p>
2316
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2317<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2318
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2319<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2320
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2321<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2322a pointer is returned.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2323
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2324<h5>Example:</h5>
2325
2326<pre>
2327 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
2328
2329 %size = <a 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]2330 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
2331 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2332 %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
2333 %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2334</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2335</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2336
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2337<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2338<div class="doc_subsubsection">
2339 <a name="i_free">'<tt>free</tt>' Instruction</a>
2340</div>
2341
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2342<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2343
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2344<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2345
2346<pre>
2347 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2348</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2349
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2350<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2351
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2352<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2353memory heap to be reallocated in the future.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2354
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2355<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2356
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2357<p>'<tt>value</tt>' shall be a pointer value that points to a value
2358that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2359instruction.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2360
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2361<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2362
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2363<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2364after this instruction executes.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2365
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2366<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2367
2368<pre>
2369 %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]2370 free [4 x ubyte]* %array
2371</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2372</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2373
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2374<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2375<div class="doc_subsubsection">
2376 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2377</div>
2378
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2379<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2380
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2381<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2382
2383<pre>
2384 &lt;result&gt; = alloca &lt;type&gt;[, uint &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2385</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2386
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2387<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2388
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2389<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2390stack frame of the procedure that is live until the current function
2391returns to its caller.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2392
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2393<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2394
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2395<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2396bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2397appropriate type to the program. If "NumElements" is specified, it is the
2398number of elements allocated. If an alignment is specified, the value result
2399of the allocation is guaranteed to be aligned to at least that boundary. If
2400not specified, or if zero, the target can choose to align the allocation on any
2401convenient boundary.</p>
2402
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2403<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2404
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2405<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2406
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2407<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2408memory is automatically released when the function returns. The '<tt>alloca</tt>'
2409instruction is commonly used to represent automatic variables that must
2410have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]2411 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]2412instructions), the memory is reclaimed.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2413
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2414<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2415
2416<pre>
2417 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2418 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2419 %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
2420 %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2421</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2422</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2423
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2424<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2425<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2426Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2427<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2428<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2429<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]2430<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2431<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2432<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2433<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2434address from which to load. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2435 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2436marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2437the number or order of execution of this <tt>load</tt> with other
2438volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2439instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2440<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2441<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2442<h5>Examples:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2443<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
2444 <a
2445 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2446 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
2447</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2448</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2449<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2450<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2451Instruction</a> </div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2452<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2453<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]2454 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]2455</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2456<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2457<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2458<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2459<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2460to store and an address in which to store it. The type of the '<tt>&lt;pointer&gt;</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2461operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2462operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2463optimizer is not allowed to modify the number or order of execution of
2464this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2465 href="#i_store">store</a></tt> instructions.</p>
2466<h5>Semantics:</h5>
2467<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2468at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2469<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2470<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
2471 <a
2472 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2473 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
2474</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2475<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2476<div class="doc_subsubsection">
2477 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2478</div>
2479
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2480<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2481<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2482<pre>
2483 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2484</pre>
2485
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2486<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2487
2488<p>
2489The '<tt>getelementptr</tt>' instruction is used to get the address of a
2490subelement of an aggregate data structure.</p>
2491
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2492<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2493
2494<p>This instruction takes a list of integer constants that indicate what
2495elements of the aggregate object to index to. The actual types of the arguments
2496provided depend on the type of the first pointer argument. The
2497'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2498levels of a structure or to a specific index in an array. When indexing into a
2499structure, only <tt>uint</tt>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2500integer constants are allowed. When indexing into an array or pointer,
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2501<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
2502
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2503<p>For example, let's consider a C code fragment and how it gets
2504compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2505
2506<pre>
2507 struct RT {
2508 char A;
2509 int B[10][20];
2510 char C;
2511 };
2512 struct ST {
2513 int X;
2514 double Y;
2515 struct RT Z;
2516 };
2517
2518 int *foo(struct ST *s) {
2519 return &amp;s[1].Z.B[5][13];
2520 }
2521</pre>
2522
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2523<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2524
2525<pre>
2526 %RT = type { sbyte, [10 x [20 x int]], sbyte }
2527 %ST = type { int, double, %RT }
2528
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2529 implementation
2530
2531 int* %foo(%ST* %s) {
2532 entry:
2533 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2534 ret int* %reg
2535 }
2536</pre>
2537
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2538<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2539
2540<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2541on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2542and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
2543<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]2544types require <tt>uint</tt> <b>constants</b>.</p>
2545
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2546<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]2547type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
2548}</tt>' type, a structure. The second index indexes into the third element of
2549the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
2550sbyte }</tt>' type, another structure. The third index indexes into the second
2551element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
2552array. The two dimensions of the array are subscripted into, yielding an
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2553'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2554to this element, thus computing a value of '<tt>int*</tt>' type.</p>
2555
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2556<p>Note that it is perfectly legal to index partially through a
2557structure, returning a pointer to an inner element. Because of this,
2558the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2559
2560<pre>
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]2561 int* %foo(%ST* %s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2562 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
2563 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
2564 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
2565 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
2566 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
2567 ret int* %t5
2568 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2569</pre>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2570
2571<p>Note that it is undefined to access an array out of bounds: array and
2572pointer indexes must always be within the defined bounds of the array type.
2573The one exception for this rules is zero length arrays. These arrays are
2574defined to be accessible as variable length arrays, which requires access
2575beyond the zero'th element.</p>
2576
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2577<p>The getelementptr instruction is often confusing. For some more insight
2578into how it works, see <a href="GetElementPtr.html">the getelementptr
2579FAQ</a>.</p>
2580
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2581<h5>Example:</h5>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2582
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2583<pre>
2584 <i>; yields [12 x ubyte]*:aptr</i>
2585 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
2586</pre>
2587
2588</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2589<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2590<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2591<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]2592<p>The instructions in this category are the "miscellaneous"
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2593instructions, which defy better classification.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2594</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2595<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2596<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2597Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2598<div class="doc_text">
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2599<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2600<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]2601<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2602<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2603the SSA graph representing the function.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2604<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2605<p>The type of the incoming values are specified with the first type
2606field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2607as arguments, with one pair for each predecessor basic block of the
2608current block. Only values of <a href="#t_firstclass">first class</a>
2609type may be used as the value arguments to the PHI node. Only labels
2610may be used as the label arguments.</p>
2611<p>There must be no non-phi instructions between the start of a basic
2612block and the PHI instructions: i.e. PHI instructions must be first in
2613a basic block.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2614<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2615<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2616value specified by the parameter, depending on which basic block we
2617came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2618<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2619<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]2620</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2621
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2622<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2623<div class="doc_subsubsection">
2624 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2625</div>
2626
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2627<div class="doc_text">
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2628
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2629<h5>Syntax:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2630
2631<pre>
2632 &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]2633</pre>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2634
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2635<h5>Overview:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2636
2637<p>
2638The '<tt>cast</tt>' instruction is used as the primitive means to convert
2639integers to floating point, change data type sizes, and break type safety (by
2640casting pointers).
2641</p>
2642
2643
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2644<h5>Arguments:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2645
2646<p>
2647The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2648class value, and a type to cast it to, which must also be a <a
2649href="#t_firstclass">first class</a> type.
2650</p>
2651
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2652<h5>Semantics:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2653
2654<p>
2655This instruction follows the C rules for explicit casts when determining how the
2656data being cast must change to fit in its new container.
2657</p>
2658
2659<p>
2660When casting to bool, any value that would be considered true in the context of
2661a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2662all else are '<tt>false</tt>'.
2663</p>
2664
2665<p>
2666When extending an integral value from a type of one signness to another (for
2667example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2668<b>source</b> value is signed, and zero-extended if the source value is
2669unsigned. <tt>bool</tt> values are always zero extended into either zero or
2670one.
2671</p>
2672
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2673<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2674
2675<pre>
2676 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattnerd8f8ede2002-06-25 18:03:17 +0000[diff] [blame]2677 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2678</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2679</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2680
2681<!-- _______________________________________________________________________ -->
2682<div class="doc_subsubsection">
2683 <a name="i_select">'<tt>select</tt>' Instruction</a>
2684</div>
2685
2686<div class="doc_text">
2687
2688<h5>Syntax:</h5>
2689
2690<pre>
2691 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2692</pre>
2693
2694<h5>Overview:</h5>
2695
2696<p>
2697The '<tt>select</tt>' instruction is used to choose one value based on a
2698condition, without branching.
2699</p>
2700
2701
2702<h5>Arguments:</h5>
2703
2704<p>
2705The '<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.
2706</p>
2707
2708<h5>Semantics:</h5>
2709
2710<p>
2711If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2712value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2713</p>
2714
2715<h5>Example:</h5>
2716
2717<pre>
2718 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2719</pre>
2720</div>
2721
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]2722
2723<!-- _______________________________________________________________________ -->
2724<div class="doc_subsubsection">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2725 <a name="i_call">'<tt>call</tt>' Instruction</a>
2726</div>
2727
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2728<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2729
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2730<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2731<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2732 &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]2733</pre>
2734
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2735<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2736
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2737<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2738
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2739<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2740
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2741<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2742
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2743<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2744 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2745 <p>The optional "tail" marker indicates whether the callee function accesses
2746 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2747 function call is eligible for tail call optimization. Note that calls may
2748 be marked "tail" even if they do not occur before a <a
2749 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2750 </li>
2751 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2752 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2753 convention</a> the call should use. If none is specified, the call defaults
2754 to using C calling conventions.
2755 </li>
2756 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2757 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2758 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2759 signature. This type can be omitted if the function is not varargs and
2760 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2761 </li>
2762 <li>
2763 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2764 be invoked. In most cases, this is a direct function invocation, but
2765 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2766 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2767 </li>
2768 <li>
2769 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]2770 function signature argument types. All arguments must be of
2771 <a href="#t_firstclass">first class</a> type. If the function signature
2772 indicates the function accepts a variable number of arguments, the extra
2773 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2774 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2775</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2776
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2777<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2778
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2779<p>The '<tt>call</tt>' instruction is used to cause control flow to
2780transfer to a specified function, with its incoming arguments bound to
2781the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2782instruction in the called function, control flow continues with the
2783instruction after the function call, and the return value of the
2784function is bound to the result argument. This is a simpler case of
2785the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2786
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2787<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2788
2789<pre>
2790 %retval = call int %test(int %argc)
2791 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2792 %X = tail call int %foo()
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]2793 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2794</pre>
2795
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2796</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2797
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2798<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2799<div class="doc_subsubsection">
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]2800 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2801</div>
2802
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2803<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2804
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2805<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2806
2807<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2808 &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2809</pre>
2810
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2811<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2812
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2813<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2814the "variable argument" area of a function call. It is used to implement the
2815<tt>va_arg</tt> macro in C.</p>
2816
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2817<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2818
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2819<p>This instruction takes a <tt>va_list*</tt> value and the type of
2820the argument. It returns a value of the specified argument type and
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]2821increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2822actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2823
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2824<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2825
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2826<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
2827type from the specified <tt>va_list</tt> and causes the
2828<tt>va_list</tt> to point to the next argument. For more information,
2829see the variable argument handling <a href="#int_varargs">Intrinsic
2830Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2831
2832<p>It is legal for this instruction to be called in a function which does not
2833take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2834function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2835
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2836<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2837href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2838argument.</p>
2839
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2840<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2841
2842<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2843
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2844</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2845
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2846<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2847<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2848<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2849
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2850<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2851
2852<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2853well known names and semantics and are required to follow certain
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2854restrictions. Overall, these instructions represent an extension mechanism for
2855the LLVM language that does not require changing all of the transformations in
2856LLVM to add to the language (or the bytecode reader/writer, the parser,
2857etc...).</p>
2858
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2859<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
2860prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2861this. Intrinsic functions must always be external functions: you cannot define
2862the body of intrinsic functions. Intrinsic functions may only be used in call
2863or invoke instructions: it is illegal to take the address of an intrinsic
2864function. Additionally, because intrinsic functions are part of the LLVM
2865language, it is required that they all be documented here if any are added.</p>
2866
2867
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2868<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner90391c12005-05-11 03:35:57 +0000[diff] [blame]2869href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2870</p>
2871
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2872</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2873
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2874<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2875<div class="doc_subsection">
2876 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2877</div>
2878
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2879<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2880
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2881<p>Variable argument support is defined in LLVM with the <a
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]2882 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2883intrinsic functions. These functions are related to the similarly
2884named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2885
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2886<p>All of these functions operate on arguments that use a
2887target-specific value type "<tt>va_list</tt>". The LLVM assembly
2888language reference manual does not define what this type is, so all
2889transformations should be prepared to handle intrinsics with any type
2890used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2891
Chris Lattner30b868d2006-05-15 17:26:46 +0000[diff] [blame]2892<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2893instruction and the variable argument handling intrinsic functions are
2894used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2895
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2896<pre>
2897int %test(int %X, ...) {
2898 ; Initialize variable argument processing
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2899 %ap = alloca sbyte*
2900 call void %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2901
2902 ; Read a single integer argument
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2903 %tmp = va_arg sbyte** %ap, int
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2904
2905 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2906 %aq = alloca sbyte*
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]2907 call void %<a href="#i_va_copy">llvm.va_copy</a>(sbyte** %aq, sbyte** %ap)
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2908 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2909
2910 ; Stop processing of arguments.
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2911 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2912 ret int %tmp
2913}
2914</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2915</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2916
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2917<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2918<div class="doc_subsubsection">
2919 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2920</div>
2921
2922
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2923<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2924<h5>Syntax:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2925<pre> declare void %llvm.va_start(&lt;va_list&gt;* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2926<h5>Overview:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2927<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
2928<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
2929href="#i_va_arg">va_arg</a></tt>.</p>
2930
2931<h5>Arguments:</h5>
2932
2933<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
2934
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2935<h5>Semantics:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2936
2937<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
2938macro available in C. In a target-dependent way, it initializes the
2939<tt>va_list</tt> element the argument points to, so that the next call to
2940<tt>va_arg</tt> will produce the first variable argument passed to the function.
2941Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2942last argument of the function, the compiler can figure that out.</p>
2943
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2944</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2945
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2946<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2947<div class="doc_subsubsection">
2948 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2949</div>
2950
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2951<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2952<h5>Syntax:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2953<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]2954<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2955<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2956which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2957or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2958<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2959<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2960<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2961<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]2962macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2963Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2964 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2965with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2966</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2967
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2968<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2969<div class="doc_subsubsection">
2970 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2971</div>
2972
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2973<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2974
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2975<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2976
2977<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2978 declare void %llvm.va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]2979 &lt;va_list&gt;* &lt;srcarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2980</pre>
2981
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2982<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2983
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2984<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
2985the source argument list to the destination argument list.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2986
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2987<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2988
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2989<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
Andrew Lenharth5305ea52005-06-22 20:38:11 +0000[diff] [blame]2990The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2991
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2992
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2993<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2994
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]2995<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
2996available in C. In a target-dependent way, it copies the source
2997<tt>va_list</tt> element into the destination list. This intrinsic is necessary
2998because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2999arbitrarily complex and require memory allocation, for example.</p>
3000
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3001</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3002
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3003<!-- ======================================================================= -->
3004<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3005 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3006</div>
3007
3008<div class="doc_text">
3009
3010<p>
3011LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3012Collection</a> requires the implementation and generation of these intrinsics.
3013These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
3014stack</a>, as well as garbage collector implementations that require <a
3015href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
3016Front-ends for type-safe garbage collected languages should generate these
3017intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3018href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3019</p>
3020</div>
3021
3022<!-- _______________________________________________________________________ -->
3023<div class="doc_subsubsection">
3024 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3025</div>
3026
3027<div class="doc_text">
3028
3029<h5>Syntax:</h5>
3030
3031<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3032 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3033</pre>
3034
3035<h5>Overview:</h5>
3036
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]3037<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]3038the code generator, and allows some metadata to be associated with it.</p>
3039
3040<h5>Arguments:</h5>
3041
3042<p>The first argument specifies the address of a stack object that contains the
3043root pointer. The second pointer (which must be either a constant or a global
3044value address) contains the meta-data to be associated with the root.</p>
3045
3046<h5>Semantics:</h5>
3047
3048<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3049location. At compile-time, the code generator generates information to allow
3050the runtime to find the pointer at GC safe points.
3051</p>
3052
3053</div>
3054
3055
3056<!-- _______________________________________________________________________ -->
3057<div class="doc_subsubsection">
3058 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
3059</div>
3060
3061<div class="doc_text">
3062
3063<h5>Syntax:</h5>
3064
3065<pre>
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3066 declare sbyte* %llvm.gcread(sbyte* %ObjPtr, sbyte** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3067</pre>
3068
3069<h5>Overview:</h5>
3070
3071<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3072locations, allowing garbage collector implementations that require read
3073barriers.</p>
3074
3075<h5>Arguments:</h5>
3076
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3077<p>The second argument is the address to read from, which should be an address
3078allocated from the garbage collector. The first object is a pointer to the
3079start of the referenced object, if needed by the language runtime (otherwise
3080null).</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3081
3082<h5>Semantics:</h5>
3083
3084<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3085instruction, but may be replaced with substantially more complex code by the
3086garbage collector runtime, as needed.</p>
3087
3088</div>
3089
3090
3091<!-- _______________________________________________________________________ -->
3092<div class="doc_subsubsection">
3093 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
3094</div>
3095
3096<div class="doc_text">
3097
3098<h5>Syntax:</h5>
3099
3100<pre>
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3101 declare void %llvm.gcwrite(sbyte* %P1, sbyte* %Obj, sbyte** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3102</pre>
3103
3104<h5>Overview:</h5>
3105
3106<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3107locations, allowing garbage collector implementations that require write
3108barriers (such as generational or reference counting collectors).</p>
3109
3110<h5>Arguments:</h5>
3111
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3112<p>The first argument is the reference to store, the second is the start of the
3113object to store it to, and the third is the address of the field of Obj to
3114store to. If the runtime does not require a pointer to the object, Obj may be
3115null.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3116
3117<h5>Semantics:</h5>
3118
3119<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3120instruction, but may be replaced with substantially more complex code by the
3121garbage collector runtime, as needed.</p>
3122
3123</div>
3124
3125
3126
3127<!-- ======================================================================= -->
3128<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3129 <a name="int_codegen">Code Generator Intrinsics</a>
3130</div>
3131
3132<div class="doc_text">
3133<p>
3134These intrinsics are provided by LLVM to expose special features that may only
3135be implemented with code generator support.
3136</p>
3137
3138</div>
3139
3140<!-- _______________________________________________________________________ -->
3141<div class="doc_subsubsection">
3142 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
3143</div>
3144
3145<div class="doc_text">
3146
3147<h5>Syntax:</h5>
3148<pre>
Chris Lattnerb3d430e2006-01-13 01:20:27 +0000[diff] [blame]3149 declare sbyte *%llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3150</pre>
3151
3152<h5>Overview:</h5>
3153
3154<p>
3155The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
3156indicating the return address of the current function or one of its callers.
3157</p>
3158
3159<h5>Arguments:</h5>
3160
3161<p>
3162The argument to this intrinsic indicates which function to return the address
3163for. Zero indicates the calling function, one indicates its caller, etc. The
3164argument is <b>required</b> to be a constant integer value.
3165</p>
3166
3167<h5>Semantics:</h5>
3168
3169<p>
3170The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3171the return address of the specified call frame, or zero if it cannot be
3172identified. The value returned by this intrinsic is likely to be incorrect or 0
3173for arguments other than zero, so it should only be used for debugging purposes.
3174</p>
3175
3176<p>
3177Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3178aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3179source-language caller.
3180</p>
3181</div>
3182
3183
3184<!-- _______________________________________________________________________ -->
3185<div class="doc_subsubsection">
3186 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
3187</div>
3188
3189<div class="doc_text">
3190
3191<h5>Syntax:</h5>
3192<pre>
Chris Lattnerb3d430e2006-01-13 01:20:27 +0000[diff] [blame]3193 declare sbyte *%llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3194</pre>
3195
3196<h5>Overview:</h5>
3197
3198<p>
3199The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
3200pointer value for the specified stack frame.
3201</p>
3202
3203<h5>Arguments:</h5>
3204
3205<p>
3206The argument to this intrinsic indicates which function to return the frame
3207pointer for. Zero indicates the calling function, one indicates its caller,
3208etc. The argument is <b>required</b> to be a constant integer value.
3209</p>
3210
3211<h5>Semantics:</h5>
3212
3213<p>
3214The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3215the frame address of the specified call frame, or zero if it cannot be
3216identified. The value returned by this intrinsic is likely to be incorrect or 0
3217for arguments other than zero, so it should only be used for debugging purposes.
3218</p>
3219
3220<p>
3221Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3222aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3223source-language caller.
3224</p>
3225</div>
3226
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3227<!-- _______________________________________________________________________ -->
3228<div class="doc_subsubsection">
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3229 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
3230</div>
3231
3232<div class="doc_text">
3233
3234<h5>Syntax:</h5>
3235<pre>
3236 declare sbyte *%llvm.stacksave()
3237</pre>
3238
3239<h5>Overview:</h5>
3240
3241<p>
3242The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
3243the function stack, for use with <a href="#i_stackrestore">
3244<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3245features like scoped automatic variable sized arrays in C99.
3246</p>
3247
3248<h5>Semantics:</h5>
3249
3250<p>
3251This intrinsic returns a opaque pointer value that can be passed to <a
3252href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
3253<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
3254<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
3255state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
3256practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
3257that were allocated after the <tt>llvm.stacksave</tt> was executed.
3258</p>
3259
3260</div>
3261
3262<!-- _______________________________________________________________________ -->
3263<div class="doc_subsubsection">
3264 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
3265</div>
3266
3267<div class="doc_text">
3268
3269<h5>Syntax:</h5>
3270<pre>
3271 declare void %llvm.stackrestore(sbyte* %ptr)
3272</pre>
3273
3274<h5>Overview:</h5>
3275
3276<p>
3277The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
3278the function stack to the state it was in when the corresponding <a
3279href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
3280useful for implementing language features like scoped automatic variable sized
3281arrays in C99.
3282</p>
3283
3284<h5>Semantics:</h5>
3285
3286<p>
3287See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
3288</p>
3289
3290</div>
3291
3292
3293<!-- _______________________________________________________________________ -->
3294<div class="doc_subsubsection">
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3295 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
3296</div>
3297
3298<div class="doc_text">
3299
3300<h5>Syntax:</h5>
3301<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3302 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
3303 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3304</pre>
3305
3306<h5>Overview:</h5>
3307
3308
3309<p>
3310The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3311a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
3312no
3313effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]3314characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3315</p>
3316
3317<h5>Arguments:</h5>
3318
3319<p>
3320<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
3321determining if the fetch should be for a read (0) or write (1), and
3322<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]3323locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3324<tt>locality</tt> arguments must be constant integers.
3325</p>
3326
3327<h5>Semantics:</h5>
3328
3329<p>
3330This intrinsic does not modify the behavior of the program. In particular,
3331prefetches cannot trap and do not produce a value. On targets that support this
3332intrinsic, the prefetch can provide hints to the processor cache for better
3333performance.
3334</p>
3335
3336</div>
3337
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]3338<!-- _______________________________________________________________________ -->
3339<div class="doc_subsubsection">
3340 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
3341</div>
3342
3343<div class="doc_text">
3344
3345<h5>Syntax:</h5>
3346<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3347 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]3348</pre>
3349
3350<h5>Overview:</h5>
3351
3352
3353<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3354The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
3355(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]3356code to simulators and other tools. The method is target specific, but it is
3357expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]3358The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnere64d41d2005-11-15 06:07:55 +0000[diff] [blame]3359after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb40261e2006-03-24 07:16:10 +0000[diff] [blame]3360optimizations. The intended use is to be inserted after optimizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3361correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]3362</p>
3363
3364<h5>Arguments:</h5>
3365
3366<p>
3367<tt>id</tt> is a numerical id identifying the marker.
3368</p>
3369
3370<h5>Semantics:</h5>
3371
3372<p>
3373This intrinsic does not modify the behavior of the program. Backends that do not
3374support this intrinisic may ignore it.
3375</p>
3376
3377</div>
3378
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]3379<!-- _______________________________________________________________________ -->
3380<div class="doc_subsubsection">
3381 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
3382</div>
3383
3384<div class="doc_text">
3385
3386<h5>Syntax:</h5>
3387<pre>
3388 declare ulong %llvm.readcyclecounter( )
3389</pre>
3390
3391<h5>Overview:</h5>
3392
3393
3394<p>
3395The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
3396counter register (or similar low latency, high accuracy clocks) on those targets
3397that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
3398As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
3399should only be used for small timings.
3400</p>
3401
3402<h5>Semantics:</h5>
3403
3404<p>
3405When directly supported, reading the cycle counter should not modify any memory.
3406Implementations are allowed to either return a application specific value or a
3407system wide value. On backends without support, this is lowered to a constant 0.
3408</p>
3409
3410</div>
3411
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3412<!-- ======================================================================= -->
3413<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3414 <a name="int_libc">Standard C Library Intrinsics</a>
3415</div>
3416
3417<div class="doc_text">
3418<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3419LLVM provides intrinsics for a few important standard C library functions.
3420These intrinsics allow source-language front-ends to pass information about the
3421alignment of the pointer arguments to the code generator, providing opportunity
3422for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3423</p>
3424
3425</div>
3426
3427<!-- _______________________________________________________________________ -->
3428<div class="doc_subsubsection">
3429 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
3430</div>
3431
3432<div class="doc_text">
3433
3434<h5>Syntax:</h5>
3435<pre>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3436 declare void %llvm.memcpy.i32(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3437 uint &lt;len&gt;, uint &lt;align&gt;)
3438 declare void %llvm.memcpy.i64(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3439 ulong &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3440</pre>
3441
3442<h5>Overview:</h5>
3443
3444<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3445The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3446location to the destination location.
3447</p>
3448
3449<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3450Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
3451intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3452</p>
3453
3454<h5>Arguments:</h5>
3455
3456<p>
3457The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3458the source. The third argument is an integer argument
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3459specifying the number of bytes to copy, and the fourth argument is the alignment
3460of the source and destination locations.
3461</p>
3462
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3463<p>
3464If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattner5316e5d2006-03-04 00:02:10 +0000[diff] [blame]3465the caller guarantees that both the source and destination pointers are aligned
3466to that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3467</p>
3468
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3469<h5>Semantics:</h5>
3470
3471<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3472The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3473location to the destination location, which are not allowed to overlap. It
3474copies "len" bytes of memory over. If the argument is known to be aligned to
3475some boundary, this can be specified as the fourth argument, otherwise it should
3476be set to 0 or 1.
3477</p>
3478</div>
3479
3480
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3481<!-- _______________________________________________________________________ -->
3482<div class="doc_subsubsection">
3483 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3484</div>
3485
3486<div class="doc_text">
3487
3488<h5>Syntax:</h5>
3489<pre>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3490 declare void %llvm.memmove.i32(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3491 uint &lt;len&gt;, uint &lt;align&gt;)
3492 declare void %llvm.memmove.i64(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3493 ulong &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3494</pre>
3495
3496<h5>Overview:</h5>
3497
3498<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3499The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
3500location to the destination location. It is similar to the
3501'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3502</p>
3503
3504<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3505Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
3506intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3507</p>
3508
3509<h5>Arguments:</h5>
3510
3511<p>
3512The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3513the source. The third argument is an integer argument
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3514specifying the number of bytes to copy, and the fourth argument is the alignment
3515of the source and destination locations.
3516</p>
3517
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3518<p>
3519If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattner5316e5d2006-03-04 00:02:10 +0000[diff] [blame]3520the caller guarantees that the source and destination pointers are aligned to
3521that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3522</p>
3523
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3524<h5>Semantics:</h5>
3525
3526<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3527The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3528location to the destination location, which may overlap. It
3529copies "len" bytes of memory over. If the argument is known to be aligned to
3530some boundary, this can be specified as the fourth argument, otherwise it should
3531be set to 0 or 1.
3532</p>
3533</div>
3534
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3535
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3536<!-- _______________________________________________________________________ -->
3537<div class="doc_subsubsection">
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3538 <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3539</div>
3540
3541<div class="doc_text">
3542
3543<h5>Syntax:</h5>
3544<pre>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3545 declare void %llvm.memset.i32(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3546 uint &lt;len&gt;, uint &lt;align&gt;)
3547 declare void %llvm.memset.i64(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3548 ulong &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3549</pre>
3550
3551<h5>Overview:</h5>
3552
3553<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3554The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3555byte value.
3556</p>
3557
3558<p>
3559Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3560does not return a value, and takes an extra alignment argument.
3561</p>
3562
3563<h5>Arguments:</h5>
3564
3565<p>
3566The first argument is a pointer to the destination to fill, the second is the
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3567byte value to fill it with, the third argument is an integer
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3568argument specifying the number of bytes to fill, and the fourth argument is the
3569known alignment of destination location.
3570</p>
3571
3572<p>
3573If the call to this intrinisic has an alignment value that is not 0 or 1, then
Chris Lattner5316e5d2006-03-04 00:02:10 +0000[diff] [blame]3574the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3575</p>
3576
3577<h5>Semantics:</h5>
3578
3579<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]3580The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
3581the
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3582destination location. If the argument is known to be aligned to some boundary,
3583this can be specified as the fourth argument, otherwise it should be set to 0 or
35841.
3585</p>
3586</div>
3587
3588
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3589<!-- _______________________________________________________________________ -->
3590<div class="doc_subsubsection">
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3591 <a name="i_isunordered">'<tt>llvm.isunordered.*</tt>' Intrinsic</a>
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3592</div>
3593
3594<div class="doc_text">
3595
3596<h5>Syntax:</h5>
3597<pre>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3598 declare bool %llvm.isunordered.f32(float Val1, float Val2)
3599 declare bool %llvm.isunordered.f64(double Val1, double Val2)
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3600</pre>
3601
3602<h5>Overview:</h5>
3603
3604<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3605The '<tt>llvm.isunordered</tt>' intrinsics return true if either or both of the
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3606specified floating point values is a NAN.
3607</p>
3608
3609<h5>Arguments:</h5>
3610
3611<p>
3612The arguments are floating point numbers of the same type.
3613</p>
3614
3615<h5>Semantics:</h5>
3616
3617<p>
3618If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3619false.
3620</p>
3621</div>
3622
3623
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]3624<!-- _______________________________________________________________________ -->
3625<div class="doc_subsubsection">
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3626 <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]3627</div>
3628
3629<div class="doc_text">
3630
3631<h5>Syntax:</h5>
3632<pre>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame^]3633 declare float %llvm.sqrt.f32(float %Val)
3634 declare double %llvm.sqrt.f64(double %Val)
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]3635</pre>
3636
3637<h5>Overview:</h5>
3638
3639<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3640The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]3641returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
3642<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
3643negative numbers (which allows for better optimization).
3644</p>
3645
3646<h5>Arguments:</h5>
3647
3648<p>
3649The argument and return value are floating point numbers of the same type.
3650</p>
3651
3652<h5>Semantics:</h5>
3653
3654<p>
3655This function returns the sqrt of the specified operand if it is a positive
3656floating point number.
3657</p>
3658</div>
3659
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame^]3660<!-- _______________________________________________________________________ -->
3661<div class="doc_subsubsection">
3662 <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
3663</div>
3664
3665<div class="doc_text">
3666
3667<h5>Syntax:</h5>
3668<pre>
3669 declare float %llvm.powi.f32(float %Val, int %power)
3670 declare double %llvm.powi.f64(double %Val, int %power)
3671</pre>
3672
3673<h5>Overview:</h5>
3674
3675<p>
3676The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
3677specified (positive or negative) power. The order of evaluation of
3678multiplications is not defined.
3679</p>
3680
3681<h5>Arguments:</h5>
3682
3683<p>
3684The second argument is an integer power, and the first is a value to raise to
3685that power.
3686</p>
3687
3688<h5>Semantics:</h5>
3689
3690<p>
3691This function returns the first value raised to the second power with an
3692unspecified sequence of rounding operations.</p>
3693</div>
3694
3695
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3696<!-- ======================================================================= -->
3697<div class="doc_subsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3698 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3699</div>
3700
3701<div class="doc_text">
3702<p>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3703LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3704These allow efficient code generation for some algorithms.
3705</p>
3706
3707</div>
3708
3709<!-- _______________________________________________________________________ -->
3710<div class="doc_subsubsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3711 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
3712</div>
3713
3714<div class="doc_text">
3715
3716<h5>Syntax:</h5>
3717<pre>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3718 declare ushort %llvm.bswap.i16(ushort &lt;id&gt;)
3719 declare uint %llvm.bswap.i32(uint &lt;id&gt;)
3720 declare ulong %llvm.bswap.i64(ulong &lt;id&gt;)
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3721</pre>
3722
3723<h5>Overview:</h5>
3724
3725<p>
3726The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
372764 bit quantity. These are useful for performing operations on data that is not
3728in the target's native byte order.
3729</p>
3730
3731<h5>Semantics:</h5>
3732
3733<p>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3734The <tt>llvm.bswap.16</tt> intrinsic returns a ushort value that has the high and low
3735byte of the input ushort swapped. Similarly, the <tt>llvm.bswap.i32</tt> intrinsic
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3736returns a uint value that has the four bytes of the input uint swapped, so that
3737if the input bytes are numbered 0, 1, 2, 3 then the returned uint will have its
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3738bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt> intrinsic extends this concept
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]3739to 64 bits.
3740</p>
3741
3742</div>
3743
3744<!-- _______________________________________________________________________ -->
3745<div class="doc_subsubsection">
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3746 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3747</div>
3748
3749<div class="doc_text">
3750
3751<h5>Syntax:</h5>
3752<pre>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3753 declare ubyte %llvm.ctpop.i8 (ubyte &lt;src&gt;)
3754 declare ushort %llvm.ctpop.i16(ushort &lt;src&gt;)
3755 declare uint %llvm.ctpop.i32(uint &lt;src&gt;)
3756 declare ulong %llvm.ctpop.i64(ulong &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3757</pre>
3758
3759<h5>Overview:</h5>
3760
3761<p>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3762The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
3763value.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3764</p>
3765
3766<h5>Arguments:</h5>
3767
3768<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3769The only argument is the value to be counted. The argument may be of any
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3770unsigned integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3771</p>
3772
3773<h5>Semantics:</h5>
3774
3775<p>
3776The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3777</p>
3778</div>
3779
3780<!-- _______________________________________________________________________ -->
3781<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]3782 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3783</div>
3784
3785<div class="doc_text">
3786
3787<h5>Syntax:</h5>
3788<pre>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3789 declare ubyte %llvm.ctlz.i8 (ubyte &lt;src&gt;)
3790 declare ushort %llvm.ctlz.i16(ushort &lt;src&gt;)
3791 declare uint %llvm.ctlz.i32(uint &lt;src&gt;)
3792 declare ulong %llvm.ctlz.i64(ulong &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3793</pre>
3794
3795<h5>Overview:</h5>
3796
3797<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3798The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
3799leading zeros in a variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3800</p>
3801
3802<h5>Arguments:</h5>
3803
3804<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]3805The only argument is the value to be counted. The argument may be of any
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3806unsigned integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3807</p>
3808
3809<h5>Semantics:</h5>
3810
3811<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3812The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
3813in a variable. If the src == 0 then the result is the size in bits of the type
Chris Lattner905bd172006-04-21 21:37:40 +0000[diff] [blame]3814of src. For example, <tt>llvm.ctlz(int 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3815</p>
3816</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3817
3818
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3819
3820<!-- _______________________________________________________________________ -->
3821<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]3822 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3823</div>
3824
3825<div class="doc_text">
3826
3827<h5>Syntax:</h5>
3828<pre>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3829 declare ubyte %llvm.cttz.i8 (ubyte &lt;src&gt;)
3830 declare ushort %llvm.cttz.i16(ushort &lt;src&gt;)
3831 declare uint %llvm.cttz.i32(uint &lt;src&gt;)
3832 declare ulong %llvm.cttz.i64(ulong &lt;src&gt;)
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3833</pre>
3834
3835<h5>Overview:</h5>
3836
3837<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]3838The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
3839trailing zeros.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3840</p>
3841
3842<h5>Arguments:</h5>
3843
3844<p>
3845The only argument is the value to be counted. The argument may be of any
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]3846unsigned integer type. The return type must match the argument type.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]3847</p>
3848
3849<h5>Semantics:</h5>
3850
3851<p>
3852The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
3853in a variable. If the src == 0 then the result is the size in bits of the type
3854of src. For example, <tt>llvm.cttz(2) = 1</tt>.
3855</p>
3856</div>
3857
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3858<!-- ======================================================================= -->
3859<div class="doc_subsection">
3860 <a name="int_debugger">Debugger Intrinsics</a>
3861</div>
3862
3863<div class="doc_text">
3864<p>
3865The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3866are described in the <a
3867href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3868Debugging</a> document.
3869</p>
3870</div>
3871
3872
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3873<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3874<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]3875<address>
3876 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
3877 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
3878 <a href="http://validator.w3.org/check/referer"><img
3879 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
3880
3881 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +0000[diff] [blame]3882 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]3883 Last modified: $Date$
3884</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3885</body>
3886</html>