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gerrit-public.fairphone.software / toolchain / llvm-project / 96a5f023929855db080afd381830ddab87a0c958 / . / llvm / docs / LangRef.html
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4<head>
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>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]27 <li><a href="#paramattrs">Parameter Attributes</a></li>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]28 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]29 <li><a href="#datalayout">Data Layout</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]30 </ol>
31 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]32 <li><a href="#typesystem">Type System</a>
33 <ol>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]34 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]35 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]36 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]37 </ol>
38 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]39 <li><a href="#t_derived">Derived Types</a>
40 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]41 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]42 <li><a href="#t_function">Function Type</a></li>
43 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]44 <li><a href="#t_struct">Structure Type</a></li>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]45 <li><a href="#t_pstruct">Packed Structure Type</a></li>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]46 <li><a href="#t_vector">Vector Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]47 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]48 </ol>
49 </li>
50 </ol>
51 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]52 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]53 <ol>
54 <li><a href="#simpleconstants">Simple Constants</a>
55 <li><a href="#aggregateconstants">Aggregate Constants</a>
56 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
57 <li><a href="#undefvalues">Undefined Values</a>
58 <li><a href="#constantexprs">Constant Expressions</a>
59 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]60 </li>
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]61 <li><a href="#othervalues">Other Values</a>
62 <ol>
63 <li><a href="#inlineasm">Inline Assembler Expressions</a>
64 </ol>
65 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]66 <li><a href="#instref">Instruction Reference</a>
67 <ol>
68 <li><a href="#terminators">Terminator Instructions</a>
69 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]70 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
71 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]72 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
73 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]74 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]75 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]76 </ol>
77 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]78 <li><a href="#binaryops">Binary Operations</a>
79 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]80 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
81 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
82 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]83 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
84 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
85 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]86 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
87 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
88 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]89 </ol>
90 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]91 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
92 <ol>
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]93 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
94 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
95 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]96 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]97 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]98 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]99 </ol>
100 </li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]101 <li><a href="#vectorops">Vector Operations</a>
102 <ol>
103 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
104 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
105 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]106 </ol>
107 </li>
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]108 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]109 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]110 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
111 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
112 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]113 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
114 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
115 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]116 </ol>
117 </li>
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]118 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]119 <ol>
120 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
121 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
122 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
123 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
124 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]125 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
126 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
127 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
128 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]129 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
130 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]131 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]132 </ol>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]133 <li><a href="#otherops">Other Operations</a>
134 <ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]135 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
136 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]137 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]138 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]139 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]140 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]141 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]142 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]143 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]144 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]145 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]146 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]147 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
148 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]149 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
150 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
151 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]152 </ol>
153 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]154 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
155 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]156 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
157 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
158 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]159 </ol>
160 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]161 <li><a href="#int_codegen">Code Generator Intrinsics</a>
162 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]163 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
164 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
165 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
166 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
167 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
168 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
169 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]170 </ol>
171 </li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]172 <li><a href="#int_libc">Standard C Library Intrinsics</a>
173 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]174 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
175 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
176 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
177 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
178 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]179 </ol>
180 </li>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]181 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]182 <ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]183 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]184 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
185 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
186 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]187 <li><a href="#int_bit_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]188 </ol>
189 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]190 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Jim Laskey2211f492007-03-14 19:31:19 +0000[diff] [blame]191 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]192 </ol>
193 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]194</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]195
196<div class="doc_author">
197 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
198 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]199</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]200
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]201<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]202<div class="doc_section"> <a name="abstract">Abstract </a></div>
203<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]204
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]205<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]206<p>This document is a reference manual for the LLVM assembly language.
207LLVM is an SSA based representation that provides type safety,
208low-level operations, flexibility, and the capability of representing
209'all' high-level languages cleanly. It is the common code
210representation used throughout all phases of the LLVM compilation
211strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]212</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]213
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]214<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]215<div class="doc_section"> <a name="introduction">Introduction</a> </div>
216<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]217
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]218<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]219
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]220<p>The LLVM code representation is designed to be used in three
221different forms: as an in-memory compiler IR, as an on-disk bytecode
222representation (suitable for fast loading by a Just-In-Time compiler),
223and as a human readable assembly language representation. This allows
224LLVM to provide a powerful intermediate representation for efficient
225compiler transformations and analysis, while providing a natural means
226to debug and visualize the transformations. The three different forms
227of LLVM are all equivalent. This document describes the human readable
228representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]229
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]230<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]231while being expressive, typed, and extensible at the same time. It
232aims to be a "universal IR" of sorts, by being at a low enough level
233that high-level ideas may be cleanly mapped to it (similar to how
234microprocessors are "universal IR's", allowing many source languages to
235be mapped to them). By providing type information, LLVM can be used as
236the target of optimizations: for example, through pointer analysis, it
237can be proven that a C automatic variable is never accessed outside of
238the current function... allowing it to be promoted to a simple SSA
239value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]240
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]241</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]242
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]243<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]244<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]245
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]246<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]247
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]248<p>It is important to note that this document describes 'well formed'
249LLVM assembly language. There is a difference between what the parser
250accepts and what is considered 'well formed'. For example, the
251following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]252
253<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]254 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]255</pre>
256
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]257<p>...because the definition of <tt>%x</tt> does not dominate all of
258its uses. The LLVM infrastructure provides a verification pass that may
259be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]260automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]261the optimizer before it outputs bytecode. The violations pointed out
262by the verifier pass indicate bugs in transformation passes or input to
263the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]264
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]265<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]266
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]267<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]268<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]269<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]270
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]271<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]272
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]273<p>LLVM uses three different forms of identifiers, for different
274purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]275
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]276<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]277 <li>Named values are represented as a string of characters with a '%' prefix.
278 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
279 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
280 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]281 with quotes. In this way, anything except a <tt>&quot;</tt> character can be used
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]282 in a name.</li>
283
284 <li>Unnamed values are represented as an unsigned numeric value with a '%'
285 prefix. For example, %12, %2, %44.</li>
286
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]287 <li>Constants, which are described in a <a href="#constants">section about
288 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]289</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]290
291<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
292don't need to worry about name clashes with reserved words, and the set of
293reserved words may be expanded in the future without penalty. Additionally,
294unnamed identifiers allow a compiler to quickly come up with a temporary
295variable without having to avoid symbol table conflicts.</p>
296
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]297<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]298languages. There are keywords for different opcodes
299('<tt><a href="#i_add">add</a></tt>',
300 '<tt><a href="#i_bitcast">bitcast</a></tt>',
301 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]302href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]303and others. These reserved words cannot conflict with variable names, because
304none of them start with a '%' character.</p>
305
306<p>Here is an example of LLVM code to multiply the integer variable
307'<tt>%X</tt>' by 8:</p>
308
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]309<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]310
311<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]312 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]313</pre>
314
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]315<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]316
317<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]318 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]319</pre>
320
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]321<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]322
323<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]324 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
325 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
326 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]327</pre>
328
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]329<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
330important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]331
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]332<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]333
334 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
335 line.</li>
336
337 <li>Unnamed temporaries are created when the result of a computation is not
338 assigned to a named value.</li>
339
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]340 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]341
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]342</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]343
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]344<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]345demonstrating instructions, we will follow an instruction with a comment that
346defines the type and name of value produced. Comments are shown in italic
347text.</p>
348
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]349</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]350
351<!-- *********************************************************************** -->
352<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
353<!-- *********************************************************************** -->
354
355<!-- ======================================================================= -->
356<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
357</div>
358
359<div class="doc_text">
360
361<p>LLVM programs are composed of "Module"s, each of which is a
362translation unit of the input programs. Each module consists of
363functions, global variables, and symbol table entries. Modules may be
364combined together with the LLVM linker, which merges function (and
365global variable) definitions, resolves forward declarations, and merges
366symbol table entries. Here is an example of the "hello world" module:</p>
367
368<pre><i>; Declare the string constant as a global constant...</i>
369<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]370 href="#globalvars">constant</a> <a href="#t_array">[13 x i8 ]</a> c"hello world\0A\00" <i>; [13 x i8 ]*</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]371
372<i>; External declaration of the puts function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]373<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]374
375<i>; Definition of main function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]376define i32 %main() { <i>; i32()* </i>
377 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]378 %cast210 = <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]379 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* %.LC0, i64 0, i64 0 <i>; i8 *</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]380
381 <i>; Call puts function to write out the string to stdout...</i>
382 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]383 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]384 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]385 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]386
387<p>This example is made up of a <a href="#globalvars">global variable</a>
388named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
389function, and a <a href="#functionstructure">function definition</a>
390for "<tt>main</tt>".</p>
391
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]392<p>In general, a module is made up of a list of global values,
393where both functions and global variables are global values. Global values are
394represented by a pointer to a memory location (in this case, a pointer to an
395array of char, and a pointer to a function), and have one of the following <a
396href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]397
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]398</div>
399
400<!-- ======================================================================= -->
401<div class="doc_subsection">
402 <a name="linkage">Linkage Types</a>
403</div>
404
405<div class="doc_text">
406
407<p>
408All Global Variables and Functions have one of the following types of linkage:
409</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]410
411<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]412
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]413 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]414
415 <dd>Global values with internal linkage are only directly accessible by
416 objects in the current module. In particular, linking code into a module with
417 an internal global value may cause the internal to be renamed as necessary to
418 avoid collisions. Because the symbol is internal to the module, all
419 references can be updated. This corresponds to the notion of the
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]420 '<tt>static</tt>' keyword in C.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]421 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]422
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]423 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]424
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]425 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
426 the same name when linkage occurs. This is typically used to implement
427 inline functions, templates, or other code which must be generated in each
428 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
429 allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]430 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]431
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]432 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]433
434 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
435 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]436 used for globals that may be emitted in multiple translation units, but that
437 are not guaranteed to be emitted into every translation unit that uses them.
438 One example of this are common globals in C, such as "<tt>int X;</tt>" at
439 global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]440 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]441
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]442 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]443
444 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
445 pointer to array type. When two global variables with appending linkage are
446 linked together, the two global arrays are appended together. This is the
447 LLVM, typesafe, equivalent of having the system linker append together
448 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]449 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]450
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]451 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
452 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
453 until linked, if not linked, the symbol becomes null instead of being an
454 undefined reference.
455 </dd>
456</dl>
457
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]458 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]459
460 <dd>If none of the above identifiers are used, the global is externally
461 visible, meaning that it participates in linkage and can be used to resolve
462 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]463 </dd>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]464
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]465 <p>
466 The next two types of linkage are targeted for Microsoft Windows platform
467 only. They are designed to support importing (exporting) symbols from (to)
468 DLLs.
469 </p>
470
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]471 <dl>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]472 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
473
474 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
475 or variable via a global pointer to a pointer that is set up by the DLL
476 exporting the symbol. On Microsoft Windows targets, the pointer name is
477 formed by combining <code>_imp__</code> and the function or variable name.
478 </dd>
479
480 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
481
482 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
483 pointer to a pointer in a DLL, so that it can be referenced with the
484 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
485 name is formed by combining <code>_imp__</code> and the function or variable
486 name.
487 </dd>
488
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]489</dl>
490
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]491<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]492variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
493variable and was linked with this one, one of the two would be renamed,
494preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
495external (i.e., lacking any linkage declarations), they are accessible
Reid Spencer92c671e2007-01-05 00:59:10 +0000[diff] [blame]496outside of the current module.</p>
497<p>It is illegal for a function <i>declaration</i>
498to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]499or <tt>extern_weak</tt>.</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]500
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]501</div>
502
503<!-- ======================================================================= -->
504<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]505 <a name="callingconv">Calling Conventions</a>
506</div>
507
508<div class="doc_text">
509
510<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
511and <a href="#i_invoke">invokes</a> can all have an optional calling convention
512specified for the call. The calling convention of any pair of dynamic
513caller/callee must match, or the behavior of the program is undefined. The
514following calling conventions are supported by LLVM, and more may be added in
515the future:</p>
516
517<dl>
518 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
519
520 <dd>This calling convention (the default if no other calling convention is
521 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]522 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencer72ba4992006-12-31 21:30:18 +0000[diff] [blame]523 prototype and implemented declaration of the function (as does normal C).
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]524 </dd>
525
526 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
527
528 <dd>This calling convention attempts to make calls as fast as possible
529 (e.g. by passing things in registers). This calling convention allows the
530 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]531 without having to conform to an externally specified ABI. Implementations of
532 this convention should allow arbitrary tail call optimization to be supported.
533 This calling convention does not support varargs and requires the prototype of
534 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]535 </dd>
536
537 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
538
539 <dd>This calling convention attempts to make code in the caller as efficient
540 as possible under the assumption that the call is not commonly executed. As
541 such, these calls often preserve all registers so that the call does not break
542 any live ranges in the caller side. This calling convention does not support
543 varargs and requires the prototype of all callees to exactly match the
544 prototype of the function definition.
545 </dd>
546
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]547 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]548
549 <dd>Any calling convention may be specified by number, allowing
550 target-specific calling conventions to be used. Target specific calling
551 conventions start at 64.
552 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]553</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]554
555<p>More calling conventions can be added/defined on an as-needed basis, to
556support pascal conventions or any other well-known target-independent
557convention.</p>
558
559</div>
560
561<!-- ======================================================================= -->
562<div class="doc_subsection">
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]563 <a name="visibility">Visibility Styles</a>
564</div>
565
566<div class="doc_text">
567
568<p>
569All Global Variables and Functions have one of the following visibility styles:
570</p>
571
572<dl>
573 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
574
575 <dd>On ELF, default visibility means that the declaration is visible to other
576 modules and, in shared libraries, means that the declared entity may be
577 overridden. On Darwin, default visibility means that the declaration is
578 visible to other modules. Default visibility corresponds to "external
579 linkage" in the language.
580 </dd>
581
582 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
583
584 <dd>Two declarations of an object with hidden visibility refer to the same
585 object if they are in the same shared object. Usually, hidden visibility
586 indicates that the symbol will not be placed into the dynamic symbol table,
587 so no other module (executable or shared library) can reference it
588 directly.
589 </dd>
590
591</dl>
592
593</div>
594
595<!-- ======================================================================= -->
596<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]597 <a name="globalvars">Global Variables</a>
598</div>
599
600<div class="doc_text">
601
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]602<p>Global variables define regions of memory allocated at compilation time
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]603instead of run-time. Global variables may optionally be initialized, may have
604an explicit section to be placed in, and may
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]605have an optional explicit alignment specified. A
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]606variable may be defined as a global "constant," which indicates that the
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]607contents of the variable will <b>never</b> be modified (enabling better
608optimization, allowing the global data to be placed in the read-only section of
609an executable, etc). Note that variables that need runtime initialization
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]610cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]611
612<p>
613LLVM explicitly allows <em>declarations</em> of global variables to be marked
614constant, even if the final definition of the global is not. This capability
615can be used to enable slightly better optimization of the program, but requires
616the language definition to guarantee that optimizations based on the
617'constantness' are valid for the translation units that do not include the
618definition.
619</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]620
621<p>As SSA values, global variables define pointer values that are in
622scope (i.e. they dominate) all basic blocks in the program. Global
623variables always define a pointer to their "content" type because they
624describe a region of memory, and all memory objects in LLVM are
625accessed through pointers.</p>
626
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]627<p>LLVM allows an explicit section to be specified for globals. If the target
628supports it, it will emit globals to the section specified.</p>
629
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]630<p>An explicit alignment may be specified for a global. If not present, or if
631the alignment is set to zero, the alignment of the global is set by the target
632to whatever it feels convenient. If an explicit alignment is specified, the
633global is forced to have at least that much alignment. All alignments must be
634a power of 2.</p>
635
Chris Lattner5760c502007-01-14 00:27:09 +0000[diff] [blame]636<p>For example, the following defines a global with an initializer, section,
637 and alignment:</p>
638
639<pre>
640 %G = constant float 1.0, section "foo", align 4
641</pre>
642
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]643</div>
644
645
646<!-- ======================================================================= -->
647<div class="doc_subsection">
648 <a name="functionstructure">Functions</a>
649</div>
650
651<div class="doc_text">
652
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]653<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
654an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]655<a href="#visibility">visibility style</a>, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]656<a href="#callingconv">calling convention</a>, a return type, an optional
657<a href="#paramattrs">parameter attribute</a> for the return type, a function
658name, a (possibly empty) argument list (each with optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]659<a href="#paramattrs">parameter attributes</a>), an optional section, an
660optional alignment, an opening curly brace, a list of basic blocks, and a
661closing curly brace.
662
663LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
664optional <a href="#linkage">linkage type</a>, an optional
665<a href="#visibility">visibility style</a>, an optional
666<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]667<a href="#paramattrs">parameter attribute</a> for the return type, a function
668name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]669
670<p>A function definition contains a list of basic blocks, forming the CFG for
671the function. Each basic block may optionally start with a label (giving the
672basic block a symbol table entry), contains a list of instructions, and ends
673with a <a href="#terminators">terminator</a> instruction (such as a branch or
674function return).</p>
675
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]676<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]677executed on entrance to the function, and it is not allowed to have predecessor
678basic blocks (i.e. there can not be any branches to the entry block of a
679function). Because the block can have no predecessors, it also cannot have any
680<a href="#i_phi">PHI nodes</a>.</p>
681
682<p>LLVM functions are identified by their name and type signature. Hence, two
683functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]684considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]685appropriately.</p>
686
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]687<p>LLVM allows an explicit section to be specified for functions. If the target
688supports it, it will emit functions to the section specified.</p>
689
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]690<p>An explicit alignment may be specified for a function. If not present, or if
691the alignment is set to zero, the alignment of the function is set by the target
692to whatever it feels convenient. If an explicit alignment is specified, the
693function is forced to have at least that much alignment. All alignments must be
694a power of 2.</p>
695
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]696</div>
697
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]698<!-- ======================================================================= -->
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]699<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
700<div class="doc_text">
701 <p>The return type and each parameter of a function type may have a set of
702 <i>parameter attributes</i> associated with them. Parameter attributes are
703 used to communicate additional information about the result or parameters of
704 a function. Parameter attributes are considered to be part of the function
705 type so two functions types that differ only by the parameter attributes
706 are different function types.</p>
707
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]708 <p>Parameter attributes are simple keywords that follow the type specified. If
709 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]710 example:</p><pre>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]711 %someFunc = i16 (i8 sext %someParam) zext
712 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]713 <p>Note that the two function types above are unique because the parameter has
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]714 a different attribute (sext in the first one, zext in the second). Also note
715 that the attribute for the function result (zext) comes immediately after the
716 argument list.</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]717
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]718 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]719 <dl>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]720 <dt><tt>zext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]721 <dd>This indicates that the parameter should be zero extended just before
722 a call to this function.</dd>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]723 <dt><tt>sext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]724 <dd>This indicates that the parameter should be sign extended just before
725 a call to this function.</dd>
Anton Korobeynikove8166852007-01-28 14:30:45 +0000[diff] [blame]726 <dt><tt>inreg</tt></dt>
727 <dd>This indicates that the parameter should be placed in register (if
Anton Korobeynikove93c6e82007-01-28 15:27:21 +0000[diff] [blame]728 possible) during assembling function call. Support for this attribute is
729 target-specific</dd>
Anton Korobeynikove8166852007-01-28 14:30:45 +0000[diff] [blame]730 <dt><tt>sret</tt></dt>
Anton Korobeynikove93c6e82007-01-28 15:27:21 +0000[diff] [blame]731 <dd>This indicates that the parameter specifies the address of a structure
Reid Spencer05dbb9d2007-03-22 02:02:11 +0000[diff] [blame]732 that is the return value of the function in the source program.</dd>
Reid Spencer9d1700e2007-03-22 02:18:56 +0000[diff] [blame]733 <dt><tt>noreturn</tt></dt>
734 <dd>This function attribute indicates that the function never returns. This
735 indicates to LLVM that every call to this function should be treated as if
736 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Reid Spencer05dbb9d2007-03-22 02:02:11 +0000[diff] [blame]737 <dt><tt>nounwind</tt></dt>
738 <dd>This function attribute indicates that the function type does not use
739 the unwind instruction and does not allow stack unwinding to propagate
740 through it.</dd>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]741 </dl>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]742
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]743</div>
744
745<!-- ======================================================================= -->
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]746<div class="doc_subsection">
Chris Lattner93564892006-04-08 04:40:53 +0000[diff] [blame]747 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]748</div>
749
750<div class="doc_text">
751<p>
752Modules may contain "module-level inline asm" blocks, which corresponds to the
753GCC "file scope inline asm" blocks. These blocks are internally concatenated by
754LLVM and treated as a single unit, but may be separated in the .ll file if
755desired. The syntax is very simple:
756</p>
757
758<div class="doc_code"><pre>
Chris Lattnera1280ad2006-01-24 00:37:20 +0000[diff] [blame]759 module asm "inline asm code goes here"
760 module asm "more can go here"
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]761</pre></div>
762
763<p>The strings can contain any character by escaping non-printable characters.
764 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
765 for the number.
766</p>
767
768<p>
769 The inline asm code is simply printed to the machine code .s file when
770 assembly code is generated.
771</p>
772</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]773
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]774<!-- ======================================================================= -->
775<div class="doc_subsection">
776 <a name="datalayout">Data Layout</a>
777</div>
778
779<div class="doc_text">
780<p>A module may specify a target specific data layout string that specifies how
781data is to be laid out in memory. The syntax for the data layout is simply:<br/>
782<pre> target datalayout = "<i>layout specification</i>"
783</pre>
784The <i>layout specification</i> consists of a list of specifications separated
785by the minus sign character ('-'). Each specification starts with a letter
786and may include other information after the letter to define some aspect of the
787data layout. The specifications accepted are as follows: </p>
788<dl>
789 <dt><tt>E</tt></dt>
790 <dd>Specifies that the target lays out data in big-endian form. That is, the
791 bits with the most significance have the lowest address location.</dd>
792 <dt><tt>e</tt></dt>
793 <dd>Specifies that hte target lays out data in little-endian form. That is,
794 the bits with the least significance have the lowest address location.</dd>
795 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
796 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
797 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
798 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
799 too.</dd>
800 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
801 <dd>This specifies the alignment for an integer type of a given bit
802 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
803 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
804 <dd>This specifies the alignment for a vector type of a given bit
805 <i>size</i>.</dd>
806 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
807 <dd>This specifies the alignment for a floating point type of a given bit
808 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
809 (double).</dd>
810 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
811 <dd>This specifies the alignment for an aggregate type of a given bit
812 <i>size</i>.</dd>
813</dl>
814<p>When constructing the data layout for a given target, LLVM starts with a
815default set of specifications which are then (possibly) overriden by the
816specifications in the <tt>datalayout</tt> keyword. The default specifications
817are given in this list:</p>
818<ul>
819 <li><tt>E</tt> - big endian</li>
820 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
821 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
822 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
823 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
824 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
825 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
826 alignment of 64-bits</li>
827 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
828 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
829 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
830 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
831 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
832</ul>
833<p>When llvm is determining the alignment for a given type, it uses the
834following rules:
835<ol>
836 <li>If the type sought is an exact match for one of the specifications, that
837 specification is used.</li>
838 <li>If no match is found, and the type sought is an integer type, then the
839 smallest integer type that is larger than the bitwidth of the sought type is
840 used. If none of the specifications are larger than the bitwidth then the the
841 largest integer type is used. For example, given the default specifications
842 above, the i7 type will use the alignment of i8 (next largest) while both
843 i65 and i256 will use the alignment of i64 (largest specified).</li>
844 <li>If no match is found, and the type sought is a vector type, then the
845 largest vector type that is smaller than the sought vector type will be used
846 as a fall back. This happens because <128 x double> can be implemented in
847 terms of 64 <2 x double>, for example.</li>
848</ol>
849</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]850
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]851<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]852<div class="doc_section"> <a name="typesystem">Type System</a> </div>
853<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]854
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]855<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]856
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]857<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]858intermediate representation. Being typed enables a number of
859optimizations to be performed on the IR directly, without having to do
860extra analyses on the side before the transformation. A strong type
861system makes it easier to read the generated code and enables novel
862analyses and transformations that are not feasible to perform on normal
863three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]864
865</div>
866
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]867<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]868<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]869<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]870<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]871system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]872
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]873<table class="layout">
874 <tr class="layout">
875 <td class="left">
876 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]877 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]878 <tr><th>Type</th><th>Description</th></tr>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]879 <tr><td><tt><a name="t_void">void</a></tt></td><td>No value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]880 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
881 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]882 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]883 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]884 </tbody>
885 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]886 </td>
887 <td class="right">
888 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]889 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]890 <tr><th>Type</th><th>Description</th></tr>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]891 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]892 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
893 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]894 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]895 </tbody>
896 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]897 </td>
898 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]899</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]900</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]901
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]902<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]903<div class="doc_subsubsection"> <a name="t_classifications">Type
904Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]905<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]906<p>These different primitive types fall into a few useful
907classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]908
909<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]910 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]911 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]912 <tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]913 <td><a name="t_integer">integer</a></td>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]914 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]915 </tr>
916 <tr>
917 <td><a name="t_floating">floating point</a></td>
918 <td><tt>float, double</tt></td>
919 </tr>
920 <tr>
921 <td><a name="t_firstclass">first class</a></td>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]922 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]923 <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]924 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]925 </tr>
926 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]927</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]928
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]929<p>The <a href="#t_firstclass">first class</a> types are perhaps the
930most important. Values of these types are the only ones which can be
931produced by instructions, passed as arguments, or used as operands to
932instructions. This means that all structures and arrays must be
933manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]934</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]935
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]936<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]937<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]938
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]939<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]940
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]941<p>The real power in LLVM comes from the derived types in the system.
942This is what allows a programmer to represent arrays, functions,
943pointers, and other useful types. Note that these derived types may be
944recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]945
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]946</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]947
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]948<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]949<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]950
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]951<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]952
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]953<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]954
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]955<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]956sequentially in memory. The array type requires a size (number of
957elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]958
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]959<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]960
961<pre>
962 [&lt;# elements&gt; x &lt;elementtype&gt;]
963</pre>
964
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]965<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]966be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]967
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]968<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]969<table class="layout">
970 <tr class="layout">
971 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]972 <tt>[40 x i32 ]</tt><br/>
973 <tt>[41 x i32 ]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]974 <tt>[40 x i8]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]975 </td>
976 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]977 Array of 40 32-bit integer values.<br/>
978 Array of 41 32-bit integer values.<br/>
979 Array of 40 8-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]980 </td>
981 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]982</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]983<p>Here are some examples of multidimensional arrays:</p>
984<table class="layout">
985 <tr class="layout">
986 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]987 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]988 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]989 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]990 </td>
991 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]992 3x4 array of 32-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]993 12x10 array of single precision floating point values.<br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]994 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]995 </td>
996 </tr>
997</table>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]998
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]999<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1000length array. Normally, accesses past the end of an array are undefined in
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1001LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1002As a special case, however, zero length arrays are recognized to be variable
1003length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1004type "{ i32, [0 x float]}", for example.</p>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1005
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1006</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1007
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1008<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1009<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1010<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1011<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1012<p>The function type can be thought of as a function signature. It
1013consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]1014Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1015(which are structures of pointers to functions), for indirect function
1016calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]1017<p>
1018The return type of a function type cannot be an aggregate type.
1019</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1020<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1021<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1022<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]1023specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1024which indicates that the function takes a variable number of arguments.
1025Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1026 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1027<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1028<table class="layout">
1029 <tr class="layout">
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1030 <td class="left"><tt>i32 (i32)</tt></td>
1031 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1032 </td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1033 </tr><tr class="layout">
Reid Spencere6a338d2007-01-15 18:28:34 +0000[diff] [blame]1034 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencer655dcc62006-12-31 07:20:23 +0000[diff] [blame]1035 </tt></td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1036 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1037 an <tt>i16</tt> that should be sign extended and a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1038 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1039 <tt>float</tt>.
1040 </td>
1041 </tr><tr class="layout">
1042 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1043 <td class="left">A vararg function that takes at least one
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1044 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1045 which returns an integer. This is the signature for <tt>printf</tt> in
1046 LLVM.
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1047 </td>
1048 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1049</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1050
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1051</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1052<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1053<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1054<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1055<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1056<p>The structure type is used to represent a collection of data members
1057together in memory. The packing of the field types is defined to match
1058the ABI of the underlying processor. The elements of a structure may
1059be any type that has a size.</p>
1060<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1061and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1062field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1063instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1064<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1065<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1066<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1067<table class="layout">
1068 <tr class="layout">
1069 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1070 <tt>{ i32, i32, i32 }</tt><br/>
1071 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1072 </td>
1073 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1074 a triple of three <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1075 A pair, where the first element is a <tt>float</tt> and the second element
1076 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1077 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1078 </td>
1079 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1080</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1081</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1082
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1083<!-- _______________________________________________________________________ -->
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1084<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1085</div>
1086<div class="doc_text">
1087<h5>Overview:</h5>
1088<p>The packed structure type is used to represent a collection of data members
1089together in memory. There is no padding between fields. Further, the alignment
1090of a packed structure is 1 byte. The elements of a packed structure may
1091be any type that has a size.</p>
1092<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1093and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1094field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1095instruction.</p>
1096<h5>Syntax:</h5>
1097<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1098<h5>Examples:</h5>
1099<table class="layout">
1100 <tr class="layout">
1101 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1102 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1103 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1104 </td>
1105 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1106 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1107 A pair, where the first element is a <tt>float</tt> and the second element
1108 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1109 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1110 </td>
1111 </tr>
1112</table>
1113</div>
1114
1115<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1116<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1117<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1118<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1119<p>As in many languages, the pointer type represents a pointer or
1120reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1121<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1122<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1123<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1124<table class="layout">
1125 <tr class="layout">
1126 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1127 <tt>[4x i32]*</tt><br/>
1128 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1129 </td>
1130 <td class="left">
1131 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1132 four <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1133 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1134 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1135 <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1136 </td>
1137 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1138</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1139</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1140
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1141<!-- _______________________________________________________________________ -->
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1142<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1143<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1144
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1145<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1146
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1147<p>A vector type is a simple derived type that represents a vector
1148of elements. Vector types are used when multiple primitive data
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1149are operated in parallel using a single instruction (SIMD).
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1150A vector type requires a size (number of
Chris Lattner330ce692005-11-10 01:44:22 +0000[diff] [blame]1151elements) and an underlying primitive data type. Vectors must have a power
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1152of two length (1, 2, 4, 8, 16 ...). Vector types are
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1153considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1154
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1155<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1156
1157<pre>
1158 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1159</pre>
1160
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1161<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1162be any integer or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1163
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1164<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1165
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1166<table class="layout">
1167 <tr class="layout">
1168 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1169 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1170 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1171 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1172 </td>
1173 <td class="left">
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1174 Vector of 4 32-bit integer values.<br/>
1175 Vector of 8 floating-point values.<br/>
1176 Vector of 2 64-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1177 </td>
1178 </tr>
1179</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1180</div>
1181
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1182<!-- _______________________________________________________________________ -->
1183<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1184<div class="doc_text">
1185
1186<h5>Overview:</h5>
1187
1188<p>Opaque types are used to represent unknown types in the system. This
1189corresponds (for example) to the C notion of a foward declared structure type.
1190In LLVM, opaque types can eventually be resolved to any type (not just a
1191structure type).</p>
1192
1193<h5>Syntax:</h5>
1194
1195<pre>
1196 opaque
1197</pre>
1198
1199<h5>Examples:</h5>
1200
1201<table class="layout">
1202 <tr class="layout">
1203 <td class="left">
1204 <tt>opaque</tt>
1205 </td>
1206 <td class="left">
1207 An opaque type.<br/>
1208 </td>
1209 </tr>
1210</table>
1211</div>
1212
1213
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1214<!-- *********************************************************************** -->
1215<div class="doc_section"> <a name="constants">Constants</a> </div>
1216<!-- *********************************************************************** -->
1217
1218<div class="doc_text">
1219
1220<p>LLVM has several different basic types of constants. This section describes
1221them all and their syntax.</p>
1222
1223</div>
1224
1225<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1226<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1227
1228<div class="doc_text">
1229
1230<dl>
1231 <dt><b>Boolean constants</b></dt>
1232
1233 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1234 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1235 </dd>
1236
1237 <dt><b>Integer constants</b></dt>
1238
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1239 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1240 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1241 integer types.
1242 </dd>
1243
1244 <dt><b>Floating point constants</b></dt>
1245
1246 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1247 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1248 notation (see below). Floating point constants must have a <a
1249 href="#t_floating">floating point</a> type. </dd>
1250
1251 <dt><b>Null pointer constants</b></dt>
1252
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1253 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1254 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1255
1256</dl>
1257
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1258<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1259of floating point constants. For example, the form '<tt>double
12600x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
12614.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1262(and the only time that they are generated by the disassembler) is when a
1263floating point constant must be emitted but it cannot be represented as a
1264decimal floating point number. For example, NaN's, infinities, and other
1265special values are represented in their IEEE hexadecimal format so that
1266assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1267
1268</div>
1269
1270<!-- ======================================================================= -->
1271<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1272</div>
1273
1274<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1275<p>Aggregate constants arise from aggregation of simple constants
1276and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1277
1278<dl>
1279 <dt><b>Structure constants</b></dt>
1280
1281 <dd>Structure constants are represented with notation similar to structure
1282 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1283 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1284 where "<tt>%G</tt>" is declared as "<tt>%G = external global i32</tt>". Structure constants
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1285 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1286 types of elements must match those specified by the type.
1287 </dd>
1288
1289 <dt><b>Array constants</b></dt>
1290
1291 <dd>Array constants are represented with notation similar to array type
1292 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1293 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1294 constants must have <a href="#t_array">array type</a>, and the number and
1295 types of elements must match those specified by the type.
1296 </dd>
1297
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1298 <dt><b>Vector constants</b></dt>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1299
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1300 <dd>Vector constants are represented with notation similar to vector type
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1301 definitions (a comma separated list of elements, surrounded by
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1302 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1303 i32 11, i32 74, i32 100 &gt;</tt>". VEctor constants must have <a
1304 href="#t_vector">vector type</a>, and the number and types of elements must
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1305 match those specified by the type.
1306 </dd>
1307
1308 <dt><b>Zero initialization</b></dt>
1309
1310 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1311 value to zero of <em>any</em> type, including scalar and aggregate types.
1312 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]1313 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1314 initializers.
1315 </dd>
1316</dl>
1317
1318</div>
1319
1320<!-- ======================================================================= -->
1321<div class="doc_subsection">
1322 <a name="globalconstants">Global Variable and Function Addresses</a>
1323</div>
1324
1325<div class="doc_text">
1326
1327<p>The addresses of <a href="#globalvars">global variables</a> and <a
1328href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1329constants. These constants are explicitly referenced when the <a
1330href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1331href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1332file:</p>
1333
1334<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1335 %X = global i32 17
1336 %Y = global i32 42
1337 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1338</pre>
1339
1340</div>
1341
1342<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1343<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1344<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1345 <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]1346 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1347 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1348
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1349 <p>Undefined values indicate to the compiler that the program is well defined
1350 no matter what value is used, giving the compiler more freedom to optimize.
1351 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1352</div>
1353
1354<!-- ======================================================================= -->
1355<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1356</div>
1357
1358<div class="doc_text">
1359
1360<p>Constant expressions are used to allow expressions involving other constants
1361to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1362href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1363that does not have side effects (e.g. load and call are not supported). The
1364following is the syntax for constant expressions:</p>
1365
1366<dl>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1367 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1368 <dd>Truncate a constant to another type. The bit size of CST must be larger
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1369 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1370
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1371 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1372 <dd>Zero extend a constant to another type. The bit size of CST must be
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1373 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1374
1375 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1376 <dd>Sign extend a constant to another type. The bit size of CST must be
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1377 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1378
1379 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1380 <dd>Truncate a floating point constant to another floating point type. The
1381 size of CST must be larger than the size of TYPE. Both types must be
1382 floating point.</dd>
1383
1384 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1385 <dd>Floating point extend a constant to another type. The size of CST must be
1386 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1387
1388 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1389 <dd>Convert a floating point constant to the corresponding unsigned integer
1390 constant. TYPE must be an integer type. CST must be floating point. If the
1391 value won't fit in the integer type, the results are undefined.</dd>
1392
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1393 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1394 <dd>Convert a floating point constant to the corresponding signed integer
1395 constant. TYPE must be an integer type. CST must be floating point. If the
1396 value won't fit in the integer type, the results are undefined.</dd>
1397
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1398 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1399 <dd>Convert an unsigned integer constant to the corresponding floating point
1400 constant. TYPE must be floating point. CST must be of integer type. If the
1401 value won't fit in the floating point type, the results are undefined.</dd>
1402
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1403 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1404 <dd>Convert a signed integer constant to the corresponding floating point
1405 constant. TYPE must be floating point. CST must be of integer type. If the
1406 value won't fit in the floating point type, the results are undefined.</dd>
1407
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1408 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1409 <dd>Convert a pointer typed constant to the corresponding integer constant
1410 TYPE must be an integer type. CST must be of pointer type. The CST value is
1411 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1412
1413 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1414 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1415 pointer type. CST must be of integer type. The CST value is zero extended,
1416 truncated, or unchanged to make it fit in a pointer size. This one is
1417 <i>really</i> dangerous!</dd>
1418
1419 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1420 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1421 identical (same number of bits). The conversion is done as if the CST value
1422 was stored to memory and read back as TYPE. In other words, no bits change
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1423 with this operator, just the type. This can be used for conversion of
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1424 vector types to any other type, as long as they have the same bit width. For
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1425 pointers it is only valid to cast to another pointer type.
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1426 </dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1427
1428 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1429
1430 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1431 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1432 instruction, the index list may have zero or more indexes, which are required
1433 to make sense for the type of "CSTPTR".</dd>
1434
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1435 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1436
1437 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1438 constants.</dd>
1439
1440 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1441 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1442
1443 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1444 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1445
1446 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1447
1448 <dd>Perform the <a href="#i_extractelement">extractelement
1449 operation</a> on constants.
1450
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1451 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1452
1453 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1454 operation</a> on constants.</dd>
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1455
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1456
1457 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1458
1459 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1460 operation</a> on constants.</dd>
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1461
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1462 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1463
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1464 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1465 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1466 binary</a> operations. The constraints on operands are the same as those for
1467 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1468 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1469</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1470</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1471
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1472<!-- *********************************************************************** -->
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1473<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1474<!-- *********************************************************************** -->
1475
1476<!-- ======================================================================= -->
1477<div class="doc_subsection">
1478<a name="inlineasm">Inline Assembler Expressions</a>
1479</div>
1480
1481<div class="doc_text">
1482
1483<p>
1484LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1485Module-Level Inline Assembly</a>) through the use of a special value. This
1486value represents the inline assembler as a string (containing the instructions
1487to emit), a list of operand constraints (stored as a string), and a flag that
1488indicates whether or not the inline asm expression has side effects. An example
1489inline assembler expression is:
1490</p>
1491
1492<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1493 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1494</pre>
1495
1496<p>
1497Inline assembler expressions may <b>only</b> be used as the callee operand of
1498a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1499</p>
1500
1501<pre>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]1502 %X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1503</pre>
1504
1505<p>
1506Inline asms with side effects not visible in the constraint list must be marked
1507as having side effects. This is done through the use of the
1508'<tt>sideeffect</tt>' keyword, like so:
1509</p>
1510
1511<pre>
1512 call void asm sideeffect "eieio", ""()
1513</pre>
1514
1515<p>TODO: The format of the asm and constraints string still need to be
1516documented here. Constraints on what can be done (e.g. duplication, moving, etc
1517need to be documented).
1518</p>
1519
1520</div>
1521
1522<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1523<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1524<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1525
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1526<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1527
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1528<p>The LLVM instruction set consists of several different
1529classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1530instructions</a>, <a href="#binaryops">binary instructions</a>,
1531<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1532 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1533instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1534
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1535</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1536
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1537<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1538<div class="doc_subsection"> <a name="terminators">Terminator
1539Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1540
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1541<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1542
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1543<p>As mentioned <a href="#functionstructure">previously</a>, every
1544basic block in a program ends with a "Terminator" instruction, which
1545indicates which block should be executed after the current block is
1546finished. These terminator instructions typically yield a '<tt>void</tt>'
1547value: they produce control flow, not values (the one exception being
1548the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1549<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1550 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1551instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1552the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1553 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1554 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1555
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1556</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1557
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1558<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1559<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1560Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1561<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1562<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1563<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]1564 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1565</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1566<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1567<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1568value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1569<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1570returns a value and then causes control flow, and one that just causes
1571control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1572<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1573<p>The '<tt>ret</tt>' instruction may return any '<a
1574 href="#t_firstclass">first class</a>' type. Notice that a function is
1575not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1576instruction inside of the function that returns a value that does not
1577match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1578<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1579<p>When the '<tt>ret</tt>' instruction is executed, control flow
1580returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1581 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1582the instruction after the call. If the caller was an "<a
1583 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1584at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1585returns a value, that value shall set the call or invoke instruction's
1586return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1587<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1588<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1589 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1590</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1591</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1592<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1593<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1594<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1595<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1596<pre> br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1597</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1598<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1599<p>The '<tt>br</tt>' instruction is used to cause control flow to
1600transfer to a different basic block in the current function. There are
1601two forms of this instruction, corresponding to a conditional branch
1602and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1603<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1604<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1605single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]1606unconditional form of the '<tt>br</tt>' instruction takes a single
1607'<tt>label</tt>' value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1608<h5>Semantics:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1609<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1610argument is evaluated. If the value is <tt>true</tt>, control flows
1611to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1612control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1613<h5>Example:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1614<pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq, i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1615 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1616</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1617<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1618<div class="doc_subsubsection">
1619 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1620</div>
1621
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1622<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1623<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1624
1625<pre>
1626 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1627</pre>
1628
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1629<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1630
1631<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1632several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1633instruction, allowing a branch to occur to one of many possible
1634destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1635
1636
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1637<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1638
1639<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1640comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1641an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1642table is not allowed to contain duplicate constant entries.</p>
1643
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1644<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1645
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1646<p>The <tt>switch</tt> instruction specifies a table of values and
1647destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1648table is searched for the given value. If the value is found, control flow is
1649transfered to the corresponding destination; otherwise, control flow is
1650transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1651
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1652<h5>Implementation:</h5>
1653
1654<p>Depending on properties of the target machine and the particular
1655<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1656ways. For example, it could be generated as a series of chained conditional
1657branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1658
1659<h5>Example:</h5>
1660
1661<pre>
1662 <i>; Emulate a conditional br instruction</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1663 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1664 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1665
1666 <i>; Emulate an unconditional br instruction</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1667 switch i32 0, label %dest [ ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1668
1669 <i>; Implement a jump table:</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1670 switch i32 %val, label %otherwise [ i32 0, label %onzero
1671 i32 1, label %onone
1672 i32 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1673</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1674</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1675
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1676<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1677<div class="doc_subsubsection">
1678 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1679</div>
1680
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1681<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1682
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1683<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1684
1685<pre>
1686 &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]1687 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1688</pre>
1689
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1690<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1691
1692<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1693function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1694'<tt>normal</tt>' label or the
1695'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1696"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1697"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1698href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1699continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1700
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1701<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1702
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1703<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1704
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1705<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1706 <li>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]1707 The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1708 convention</a> the call should use. If none is specified, the call defaults
1709 to using C calling conventions.
1710 </li>
1711 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1712 function value being invoked. In most cases, this is a direct function
1713 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1714 an arbitrary pointer to function value.
1715 </li>
1716
1717 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1718 function to be invoked. </li>
1719
1720 <li>'<tt>function args</tt>': argument list whose types match the function
1721 signature argument types. If the function signature indicates the function
1722 accepts a variable number of arguments, the extra arguments can be
1723 specified. </li>
1724
1725 <li>'<tt>normal label</tt>': the label reached when the called function
1726 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1727
1728 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1729 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1730
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1731</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1732
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1733<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1734
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1735<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1736href="#i_call">call</a></tt>' instruction in most regards. The primary
1737difference is that it establishes an association with a label, which is used by
1738the runtime library to unwind the stack.</p>
1739
1740<p>This instruction is used in languages with destructors to ensure that proper
1741cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1742exception. Additionally, this is important for implementation of
1743'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1744
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1745<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1746<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1747 %retval = invoke i32 %Test(i32 15) to label %Continue
1748 unwind label %TestCleanup <i>; {i32}:retval set</i>
1749 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1750 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1751</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1752</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1753
1754
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1755<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1756
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1757<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1758Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1759
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1760<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1761
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1762<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1763<pre>
1764 unwind
1765</pre>
1766
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1767<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1768
1769<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1770at the first callee in the dynamic call stack which used an <a
1771href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1772primarily used to implement exception handling.</p>
1773
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1774<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1775
1776<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1777immediately halt. The dynamic call stack is then searched for the first <a
1778href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1779execution continues at the "exceptional" destination block specified by the
1780<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1781dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1782</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1783
1784<!-- _______________________________________________________________________ -->
1785
1786<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1787Instruction</a> </div>
1788
1789<div class="doc_text">
1790
1791<h5>Syntax:</h5>
1792<pre>
1793 unreachable
1794</pre>
1795
1796<h5>Overview:</h5>
1797
1798<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1799instruction is used to inform the optimizer that a particular portion of the
1800code is not reachable. This can be used to indicate that the code after a
1801no-return function cannot be reached, and other facts.</p>
1802
1803<h5>Semantics:</h5>
1804
1805<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1806</div>
1807
1808
1809
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1810<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1811<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1812<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1813<p>Binary operators are used to do most of the computation in a
1814program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1815produce a single value. The operands might represent
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1816multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1817The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1818necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1819<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1820</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1821<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1822<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1823Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1824<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1825<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1826<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]1827</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1828<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1829<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1830<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1831<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1832 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1833 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1834Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1835<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1836<p>The value produced is the integer or floating point sum of the two
1837operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1838<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1839<pre> &lt;result&gt; = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1840</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1841</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1842<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1843<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1844Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1845<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1846<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1847<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]1848</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1849<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1850<p>The '<tt>sub</tt>' instruction returns the difference of its two
1851operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1852<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1853instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1854<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1855<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1856 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1857values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1858This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1859Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1860<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1861<p>The value produced is the integer or floating point difference of
1862the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1863<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1864<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1865 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1866</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1867</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1868<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1869<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1870Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1871<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1872<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1873<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]1874</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1875<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1876<p>The '<tt>mul</tt>' instruction returns the product of its two
1877operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1878<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1879<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1880 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1881values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1882This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1883Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1884<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1885<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1886two operands.</p>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1887<p>Because the operands are the same width, the result of an integer
1888multiplication is the same whether the operands should be deemed unsigned or
1889signed.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1890<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1891<pre> &lt;result&gt; = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1892</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1893</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1894<!-- _______________________________________________________________________ -->
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1895<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1896</a></div>
1897<div class="doc_text">
1898<h5>Syntax:</h5>
1899<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1900</pre>
1901<h5>Overview:</h5>
1902<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1903operands.</p>
1904<h5>Arguments:</h5>
1905<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1906<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1907types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1908of the values in which case the elements must be integers.</p>
1909<h5>Semantics:</h5>
1910<p>The value produced is the unsigned integer quotient of the two operands. This
1911instruction always performs an unsigned division operation, regardless of
1912whether the arguments are unsigned or not.</p>
1913<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1914<pre> &lt;result&gt; = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1915</pre>
1916</div>
1917<!-- _______________________________________________________________________ -->
1918<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1919</a> </div>
1920<div class="doc_text">
1921<h5>Syntax:</h5>
1922<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1923</pre>
1924<h5>Overview:</h5>
1925<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1926operands.</p>
1927<h5>Arguments:</h5>
1928<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1929<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1930types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1931of the values in which case the elements must be integers.</p>
1932<h5>Semantics:</h5>
1933<p>The value produced is the signed integer quotient of the two operands. This
1934instruction always performs a signed division operation, regardless of whether
1935the arguments are signed or not.</p>
1936<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1937<pre> &lt;result&gt; = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1938</pre>
1939</div>
1940<!-- _______________________________________________________________________ -->
1941<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1942Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1943<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1944<h5>Syntax:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1945<pre> &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1946</pre>
1947<h5>Overview:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1948<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1949operands.</p>
1950<h5>Arguments:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1951<p>The two arguments to the '<tt>div</tt>' instruction must be
1952<a href="#t_floating">floating point</a> values. Both arguments must have
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1953identical types. This instruction can also take <a href="#t_vector">vector</a>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1954versions of the values in which case the elements must be floating point.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1955<h5>Semantics:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1956<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1957<h5>Example:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1958<pre> &lt;result&gt; = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1959</pre>
1960</div>
1961<!-- _______________________________________________________________________ -->
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1962<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1963</div>
1964<div class="doc_text">
1965<h5>Syntax:</h5>
1966<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1967</pre>
1968<h5>Overview:</h5>
1969<p>The '<tt>urem</tt>' instruction returns the remainder from the
1970unsigned division of its two arguments.</p>
1971<h5>Arguments:</h5>
1972<p>The two arguments to the '<tt>urem</tt>' instruction must be
1973<a href="#t_integer">integer</a> values. Both arguments must have identical
1974types.</p>
1975<h5>Semantics:</h5>
1976<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1977This instruction always performs an unsigned division to get the remainder,
1978regardless of whether the arguments are unsigned or not.</p>
1979<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1980<pre> &lt;result&gt; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1981</pre>
1982
1983</div>
1984<!-- _______________________________________________________________________ -->
1985<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1986Instruction</a> </div>
1987<div class="doc_text">
1988<h5>Syntax:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1989<pre> &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1990</pre>
1991<h5>Overview:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1992<p>The '<tt>srem</tt>' instruction returns the remainder from the
1993signed division of its two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1994<h5>Arguments:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1995<p>The two arguments to the '<tt>srem</tt>' instruction must be
1996<a href="#t_integer">integer</a> values. Both arguments must have identical
1997types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1998<h5>Semantics:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1999<p>This instruction returns the <i>remainder</i> of a division (where the result
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2000has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2001operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2002a value. For more information about the difference, see <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2003 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2004Math Forum</a>. For a table of how this is implemented in various languages,
Reid Spencerdb3b93b2007-03-24 22:40:44 +0000[diff] [blame]2005please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2006Wikipedia: modulo operation</a>.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2007<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2008<pre> &lt;result&gt; = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2009</pre>
2010
2011</div>
2012<!-- _______________________________________________________________________ -->
2013<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2014Instruction</a> </div>
2015<div class="doc_text">
2016<h5>Syntax:</h5>
2017<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2018</pre>
2019<h5>Overview:</h5>
2020<p>The '<tt>frem</tt>' instruction returns the remainder from the
2021division of its two operands.</p>
2022<h5>Arguments:</h5>
2023<p>The two arguments to the '<tt>frem</tt>' instruction must be
2024<a href="#t_floating">floating point</a> values. Both arguments must have
2025identical types.</p>
2026<h5>Semantics:</h5>
2027<p>This instruction returns the <i>remainder</i> of a division.</p>
2028<h5>Example:</h5>
2029<pre> &lt;result&gt; = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2030</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2031</div>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]2032
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]2033<!-- ======================================================================= -->
2034<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2035Operations</a> </div>
2036<div class="doc_text">
2037<p>Bitwise binary operators are used to do various forms of
2038bit-twiddling in a program. They are generally very efficient
2039instructions and can commonly be strength reduced from other
2040instructions. They require two operands, execute an operation on them,
2041and produce a single value. The resulting value of the bitwise binary
2042operators is always the same type as its first operand.</p>
2043</div>
2044
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2045<!-- _______________________________________________________________________ -->
2046<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2047Instruction</a> </div>
2048<div class="doc_text">
2049<h5>Syntax:</h5>
2050<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2051</pre>
2052<h5>Overview:</h5>
2053<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2054the left a specified number of bits.</p>
2055<h5>Arguments:</h5>
2056<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2057 href="#t_integer">integer</a> type.</p>
2058<h5>Semantics:</h5>
2059<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
2060<h5>Example:</h5><pre>
2061 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2062 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2063 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
2064</pre>
2065</div>
2066<!-- _______________________________________________________________________ -->
2067<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2068Instruction</a> </div>
2069<div class="doc_text">
2070<h5>Syntax:</h5>
2071<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2072</pre>
2073
2074<h5>Overview:</h5>
2075<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2076operand shifted to the right a specified number of bits.</p>
2077
2078<h5>Arguments:</h5>
2079<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2080<a href="#t_integer">integer</a> type.</p>
2081
2082<h5>Semantics:</h5>
2083<p>This instruction always performs a logical shift right operation. The most
2084significant bits of the result will be filled with zero bits after the
2085shift.</p>
2086
2087<h5>Example:</h5>
2088<pre>
2089 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2090 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2091 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2092 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2093</pre>
2094</div>
2095
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]2096<!-- _______________________________________________________________________ -->
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2097<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2098Instruction</a> </div>
2099<div class="doc_text">
2100
2101<h5>Syntax:</h5>
2102<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2103</pre>
2104
2105<h5>Overview:</h5>
2106<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2107operand shifted to the right a specified number of bits.</p>
2108
2109<h5>Arguments:</h5>
2110<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2111<a href="#t_integer">integer</a> type.</p>
2112
2113<h5>Semantics:</h5>
2114<p>This instruction always performs an arithmetic shift right operation,
2115The most significant bits of the result will be filled with the sign bit
2116of <tt>var1</tt>.</p>
2117
2118<h5>Example:</h5>
2119<pre>
2120 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2121 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2122 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2123 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
2124</pre>
2125</div>
2126
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2127<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2128<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2129Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2130<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2131<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2132<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]2133</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2134<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2135<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2136its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2137<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2138<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2139 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2140identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2141<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2142<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2143<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2144<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2145<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2146 <tbody>
2147 <tr>
2148 <td>In0</td>
2149 <td>In1</td>
2150 <td>Out</td>
2151 </tr>
2152 <tr>
2153 <td>0</td>
2154 <td>0</td>
2155 <td>0</td>
2156 </tr>
2157 <tr>
2158 <td>0</td>
2159 <td>1</td>
2160 <td>0</td>
2161 </tr>
2162 <tr>
2163 <td>1</td>
2164 <td>0</td>
2165 <td>0</td>
2166 </tr>
2167 <tr>
2168 <td>1</td>
2169 <td>1</td>
2170 <td>1</td>
2171 </tr>
2172 </tbody>
2173</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2174</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2175<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2176<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2177 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2178 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2179</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2180</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2181<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2182<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2183<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2184<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2185<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]2186</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2187<h5>Overview:</h5>
2188<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2189or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2190<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2191<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2192 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2193identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2194<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2195<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2196<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2197<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2198<table border="1" cellspacing="0" cellpadding="4">
2199 <tbody>
2200 <tr>
2201 <td>In0</td>
2202 <td>In1</td>
2203 <td>Out</td>
2204 </tr>
2205 <tr>
2206 <td>0</td>
2207 <td>0</td>
2208 <td>0</td>
2209 </tr>
2210 <tr>
2211 <td>0</td>
2212 <td>1</td>
2213 <td>1</td>
2214 </tr>
2215 <tr>
2216 <td>1</td>
2217 <td>0</td>
2218 <td>1</td>
2219 </tr>
2220 <tr>
2221 <td>1</td>
2222 <td>1</td>
2223 <td>1</td>
2224 </tr>
2225 </tbody>
2226</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2227</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2228<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2229<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2230 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2231 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2232</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2233</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2234<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2235<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2236Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2237<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2238<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2239<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]2240</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2241<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2242<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2243or of its two operands. The <tt>xor</tt> is used to implement the
2244"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2245<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2246<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2247 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2248identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2249<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2250<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2251<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2252<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2253<table border="1" cellspacing="0" cellpadding="4">
2254 <tbody>
2255 <tr>
2256 <td>In0</td>
2257 <td>In1</td>
2258 <td>Out</td>
2259 </tr>
2260 <tr>
2261 <td>0</td>
2262 <td>0</td>
2263 <td>0</td>
2264 </tr>
2265 <tr>
2266 <td>0</td>
2267 <td>1</td>
2268 <td>1</td>
2269 </tr>
2270 <tr>
2271 <td>1</td>
2272 <td>0</td>
2273 <td>1</td>
2274 </tr>
2275 <tr>
2276 <td>1</td>
2277 <td>1</td>
2278 <td>0</td>
2279 </tr>
2280 </tbody>
2281</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2282</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2283<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2284<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2285<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2286 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2287 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2288 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2289</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2290</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2291
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2292<!-- ======================================================================= -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2293<div class="doc_subsection">
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2294 <a name="vectorops">Vector Operations</a>
2295</div>
2296
2297<div class="doc_text">
2298
2299<p>LLVM supports several instructions to represent vector operations in a
2300target-independent manner. This instructions cover the element-access and
2301vector-specific operations needed to process vectors effectively. While LLVM
2302does directly support these vector operations, many sophisticated algorithms
2303will want to use target-specific intrinsics to take full advantage of a specific
2304target.</p>
2305
2306</div>
2307
2308<!-- _______________________________________________________________________ -->
2309<div class="doc_subsubsection">
2310 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2311</div>
2312
2313<div class="doc_text">
2314
2315<h5>Syntax:</h5>
2316
2317<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2318 &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt; <i>; yields &lt;ty&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2319</pre>
2320
2321<h5>Overview:</h5>
2322
2323<p>
2324The '<tt>extractelement</tt>' instruction extracts a single scalar
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2325element from a vector at a specified index.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2326</p>
2327
2328
2329<h5>Arguments:</h5>
2330
2331<p>
2332The first operand of an '<tt>extractelement</tt>' instruction is a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2333value of <a href="#t_vector">vector</a> type. The second operand is
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2334an index indicating the position from which to extract the element.
2335The index may be a variable.</p>
2336
2337<h5>Semantics:</h5>
2338
2339<p>
2340The result is a scalar of the same type as the element type of
2341<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2342<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2343results are undefined.
2344</p>
2345
2346<h5>Example:</h5>
2347
2348<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2349 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2350</pre>
2351</div>
2352
2353
2354<!-- _______________________________________________________________________ -->
2355<div class="doc_subsubsection">
2356 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2357</div>
2358
2359<div class="doc_text">
2360
2361<h5>Syntax:</h5>
2362
2363<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2364 &lt;result&gt; = insertelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, &lt;ty&gt; &lt;elt&gt, i32 &lt;idx&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2365</pre>
2366
2367<h5>Overview:</h5>
2368
2369<p>
2370The '<tt>insertelement</tt>' instruction inserts a scalar
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2371element into a vector at a specified index.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2372</p>
2373
2374
2375<h5>Arguments:</h5>
2376
2377<p>
2378The first operand of an '<tt>insertelement</tt>' instruction is a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2379value of <a href="#t_vector">vector</a> type. The second operand is a
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2380scalar value whose type must equal the element type of the first
2381operand. The third operand is an index indicating the position at
2382which to insert the value. The index may be a variable.</p>
2383
2384<h5>Semantics:</h5>
2385
2386<p>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2387The result is a vector of the same type as <tt>val</tt>. Its
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2388element values are those of <tt>val</tt> except at position
2389<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2390exceeds the length of <tt>val</tt>, the results are undefined.
2391</p>
2392
2393<h5>Example:</h5>
2394
2395<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2396 %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0 <i>; yields &lt;4 x i32&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2397</pre>
2398</div>
2399
2400<!-- _______________________________________________________________________ -->
2401<div class="doc_subsubsection">
2402 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2403</div>
2404
2405<div class="doc_text">
2406
2407<h5>Syntax:</h5>
2408
2409<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2410 &lt;result&gt; = shufflevector &lt;n x &lt;ty&gt;&gt; &lt;v1&gt;, &lt;n x &lt;ty&gt;&gt; &lt;v2&gt;, &lt;n x i32&gt; &lt;mask&gt; <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2411</pre>
2412
2413<h5>Overview:</h5>
2414
2415<p>
2416The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2417from two input vectors, returning a vector of the same type.
2418</p>
2419
2420<h5>Arguments:</h5>
2421
2422<p>
2423The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2424with types that match each other and types that match the result of the
2425instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2426of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2427</p>
2428
2429<p>
2430The shuffle mask operand is required to be a constant vector with either
2431constant integer or undef values.
2432</p>
2433
2434<h5>Semantics:</h5>
2435
2436<p>
2437The elements of the two input vectors are numbered from left to right across
2438both of the vectors. The shuffle mask operand specifies, for each element of
2439the result vector, which element of the two input registers the result element
2440gets. The element selector may be undef (meaning "don't care") and the second
2441operand may be undef if performing a shuffle from only one vector.
2442</p>
2443
2444<h5>Example:</h5>
2445
2446<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2447 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2448 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2449 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2450 &lt;4 x i32&gt; &lt;i32 0, i32 1, i32 2, i32 3&gt; <i>; yields &lt;4 x i32&gt;</i> - Identity shuffle.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2451</pre>
2452</div>
2453
Tanya Lattnerb138bbe2006-04-14 19:24:33 +0000[diff] [blame]2454
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2455<!-- ======================================================================= -->
2456<div class="doc_subsection">
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2457 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2458</div>
2459
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2460<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2461
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2462<p>A key design point of an SSA-based representation is how it
2463represents memory. In LLVM, no memory locations are in SSA form, which
2464makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2465allocate, and free memory in LLVM.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2466
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2467</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2468
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2469<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2470<div class="doc_subsubsection">
2471 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2472</div>
2473
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2474<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2475
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2476<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2477
2478<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2479 &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2480</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2481
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2482<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2483
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2484<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2485heap and returns a pointer to it.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2486
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2487<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2488
2489<p>The '<tt>malloc</tt>' instruction allocates
2490<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]2491bytes of memory from the operating system and returns a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2492appropriate type to the program. If "NumElements" is specified, it is the
2493number of elements allocated. If an alignment is specified, the value result
2494of the allocation is guaranteed to be aligned to at least that boundary. If
2495not specified, or if zero, the target can choose to align the allocation on any
2496convenient boundary.</p>
2497
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2498<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2499
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2500<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2501
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2502<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2503a pointer is returned.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2504
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2505<h5>Example:</h5>
2506
2507<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2508 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2509
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2510 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2511 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2512 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2513 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2514 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2515</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2516</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2517
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2518<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2519<div class="doc_subsubsection">
2520 <a name="i_free">'<tt>free</tt>' Instruction</a>
2521</div>
2522
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2523<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2524
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2525<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2526
2527<pre>
2528 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2529</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2530
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2531<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2532
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2533<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2534memory heap to be reallocated in the future.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2535
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2536<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2537
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2538<p>'<tt>value</tt>' shall be a pointer value that points to a value
2539that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2540instruction.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2541
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2542<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2543
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2544<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2545after this instruction executes.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2546
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2547<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2548
2549<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2550 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2551 free [4 x i8]* %array
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2552</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2553</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2554
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2555<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2556<div class="doc_subsubsection">
2557 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2558</div>
2559
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2560<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2561
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2562<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2563
2564<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2565 &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;] <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2566</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2567
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2568<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2569
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2570<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2571stack frame of the procedure that is live until the current function
2572returns to its caller.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2573
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2574<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2575
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2576<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2577bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2578appropriate type to the program. If "NumElements" is specified, it is the
2579number of elements allocated. If an alignment is specified, the value result
2580of the allocation is guaranteed to be aligned to at least that boundary. If
2581not specified, or if zero, the target can choose to align the allocation on any
2582convenient boundary.</p>
2583
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2584<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2585
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2586<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2587
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2588<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2589memory is automatically released when the function returns. The '<tt>alloca</tt>'
2590instruction is commonly used to represent automatic variables that must
2591have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]2592 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]2593instructions), the memory is reclaimed.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2594
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2595<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2596
2597<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2598 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2599 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2600 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2601 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2602</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2603</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2604
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2605<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2606<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2607Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2608<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2609<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2610<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]2611<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2612<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2613<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2614<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2615address from which to load. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2616 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2617marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2618the number or order of execution of this <tt>load</tt> with other
2619volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2620instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2621<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2622<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2623<h5>Examples:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2624<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2625 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2626 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2627 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2628</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2629</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2630<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2631<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2632Instruction</a> </div>
Reid Spencera89fb182006-11-09 21:18:01 +0000[diff] [blame]2633<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2634<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2635<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]2636 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]2637</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2638<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2639<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2640<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2641<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2642to 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]2643operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2644operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2645optimizer is not allowed to modify the number or order of execution of
2646this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2647 href="#i_store">store</a></tt> instructions.</p>
2648<h5>Semantics:</h5>
2649<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2650at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2651<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2652<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2653 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2654 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2655 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2656</pre>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2657</div>
2658
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2659<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2660<div class="doc_subsubsection">
2661 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2662</div>
2663
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2664<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2665<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2666<pre>
2667 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2668</pre>
2669
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2670<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2671
2672<p>
2673The '<tt>getelementptr</tt>' instruction is used to get the address of a
2674subelement of an aggregate data structure.</p>
2675
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2676<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2677
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2678<p>This instruction takes a list of integer operands that indicate what
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2679elements of the aggregate object to index to. The actual types of the arguments
2680provided depend on the type of the first pointer argument. The
2681'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2682levels of a structure or to a specific index in an array. When indexing into a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2683structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2684into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2685be sign extended to 64-bit values.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2686
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2687<p>For example, let's consider a C code fragment and how it gets
2688compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2689
2690<pre>
2691 struct RT {
2692 char A;
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2693 i32 B[10][20];
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2694 char C;
2695 };
2696 struct ST {
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2697 i32 X;
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2698 double Y;
2699 struct RT Z;
2700 };
2701
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2702 define i32 *foo(struct ST *s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2703 return &amp;s[1].Z.B[5][13];
2704 }
2705</pre>
2706
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2707<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2708
2709<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2710 %RT = type { i8 , [10 x [20 x i32]], i8 }
2711 %ST = type { i32, double, %RT }
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2712
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2713 define i32* %foo(%ST* %s) {
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2714 entry:
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2715 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2716 ret i32* %reg
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2717 }
2718</pre>
2719
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2720<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2721
2722<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2723on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2724and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
Reid Spencerc0312692006-12-03 16:53:48 +0000[diff] [blame]2725<a href="#t_integer">integer</a> type but the value will always be sign extended
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2726to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencerc0312692006-12-03 16:53:48 +0000[diff] [blame]2727<b>constants</b>.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2728
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2729<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2730type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2731}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2732the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2733i8 }</tt>' type, another structure. The third index indexes into the second
2734element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2735array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2736'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2737to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2738
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2739<p>Note that it is perfectly legal to index partially through a
2740structure, returning a pointer to an inner element. Because of this,
2741the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2742
2743<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2744 define i32* %foo(%ST* %s) {
2745 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2746 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2747 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2748 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2749 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2750 ret i32* %t5
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2751 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2752</pre>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2753
2754<p>Note that it is undefined to access an array out of bounds: array and
2755pointer indexes must always be within the defined bounds of the array type.
2756The one exception for this rules is zero length arrays. These arrays are
2757defined to be accessible as variable length arrays, which requires access
2758beyond the zero'th element.</p>
2759
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2760<p>The getelementptr instruction is often confusing. For some more insight
2761into how it works, see <a href="GetElementPtr.html">the getelementptr
2762FAQ</a>.</p>
2763
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2764<h5>Example:</h5>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2765
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2766<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2767 <i>; yields [12 x i8]*:aptr</i>
2768 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2769</pre>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2770</div>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2771
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2772<!-- ======================================================================= -->
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2773<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2774</div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2775<div class="doc_text">
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2776<p>The instructions in this category are the conversion instructions (casting)
2777which all take a single operand and a type. They perform various bit conversions
2778on the operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2779</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2780
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2781<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2782<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2783 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2784</div>
2785<div class="doc_text">
2786
2787<h5>Syntax:</h5>
2788<pre>
2789 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2790</pre>
2791
2792<h5>Overview:</h5>
2793<p>
2794The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2795</p>
2796
2797<h5>Arguments:</h5>
2798<p>
2799The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2800be an <a href="#t_integer">integer</a> type, and a type that specifies the size
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2801and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2802type. The bit size of <tt>value</tt> must be larger than the bit size of
2803<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2804
2805<h5>Semantics:</h5>
2806<p>
2807The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2808and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2809larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2810It will always truncate bits.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2811
2812<h5>Example:</h5>
2813<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2814 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2815 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2816 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2817</pre>
2818</div>
2819
2820<!-- _______________________________________________________________________ -->
2821<div class="doc_subsubsection">
2822 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2823</div>
2824<div class="doc_text">
2825
2826<h5>Syntax:</h5>
2827<pre>
2828 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2829</pre>
2830
2831<h5>Overview:</h5>
2832<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2833<tt>ty2</tt>.</p>
2834
2835
2836<h5>Arguments:</h5>
2837<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2838<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2839also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2840<tt>value</tt> must be smaller than the bit size of the destination type,
2841<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2842
2843<h5>Semantics:</h5>
2844<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2845bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2846the operand and the type are the same size, no bit filling is done and the
2847cast is considered a <i>no-op cast</i> because no bits change (only the type
2848changes).</p>
2849
Reid Spencer07c9c682007-01-12 15:46:11 +0000[diff] [blame]2850<p>When zero extending from i1, the result will always be either 0 or 1.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2851
2852<h5>Example:</h5>
2853<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2854 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2855 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2856</pre>
2857</div>
2858
2859<!-- _______________________________________________________________________ -->
2860<div class="doc_subsubsection">
2861 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2862</div>
2863<div class="doc_text">
2864
2865<h5>Syntax:</h5>
2866<pre>
2867 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2868</pre>
2869
2870<h5>Overview:</h5>
2871<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2872
2873<h5>Arguments:</h5>
2874<p>
2875The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2876<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2877also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2878<tt>value</tt> must be smaller than the bit size of the destination type,
2879<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2880
2881<h5>Semantics:</h5>
2882<p>
2883The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2884bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2885the type <tt>ty2</tt>. When the the operand and the type are the same size,
2886no bit filling is done and the cast is considered a <i>no-op cast</i> because
2887no bits change (only the type changes).</p>
2888
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2889<p>When sign extending from i1, the extension always results in -1 or 0.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2890
2891<h5>Example:</h5>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2892<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2893 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2894 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2895</pre>
2896</div>
2897
2898<!-- _______________________________________________________________________ -->
2899<div class="doc_subsubsection">
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2900 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2901</div>
2902
2903<div class="doc_text">
2904
2905<h5>Syntax:</h5>
2906
2907<pre>
2908 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2909</pre>
2910
2911<h5>Overview:</h5>
2912<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2913<tt>ty2</tt>.</p>
2914
2915
2916<h5>Arguments:</h5>
2917<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2918 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2919cast it to. The size of <tt>value</tt> must be larger than the size of
2920<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2921<i>no-op cast</i>.</p>
2922
2923<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2924<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2925<a href="#t_floating">floating point</a> type to a smaller
2926<a href="#t_floating">floating point</a> type. If the value cannot fit within
2927the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2928
2929<h5>Example:</h5>
2930<pre>
2931 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2932 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2933</pre>
2934</div>
2935
2936<!-- _______________________________________________________________________ -->
2937<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2938 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2939</div>
2940<div class="doc_text">
2941
2942<h5>Syntax:</h5>
2943<pre>
2944 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2945</pre>
2946
2947<h5>Overview:</h5>
2948<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2949floating point value.</p>
2950
2951<h5>Arguments:</h5>
2952<p>The '<tt>fpext</tt>' instruction takes a
2953<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2954and a <a href="#t_floating">floating point</a> type to cast it to. The source
2955type must be smaller than the destination type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2956
2957<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2958<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]2959<a href="#t_floating">floating point</a> type to a larger
2960<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2961used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]2962<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2963
2964<h5>Example:</h5>
2965<pre>
2966 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2967 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2968</pre>
2969</div>
2970
2971<!-- _______________________________________________________________________ -->
2972<div class="doc_subsubsection">
Reid Spencer2eadb532007-01-21 00:29:26 +0000[diff] [blame]2973 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2974</div>
2975<div class="doc_text">
2976
2977<h5>Syntax:</h5>
2978<pre>
2979 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2980</pre>
2981
2982<h5>Overview:</h5>
2983<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2984unsigned integer equivalent of type <tt>ty2</tt>.
2985</p>
2986
2987<h5>Arguments:</h5>
2988<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2989<a href="#t_floating">floating point</a> value, and a type to cast it to, which
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2990must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2991
2992<h5>Semantics:</h5>
2993<p> The '<tt>fp2uint</tt>' instruction converts its
2994<a href="#t_floating">floating point</a> operand into the nearest (rounding
2995towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2996the results are undefined.</p>
2997
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2998<p>When converting to i1, the conversion is done as a comparison against
2999zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3000If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3001
3002<h5>Example:</h5>
3003<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3004 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
3005 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3006 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3007</pre>
3008</div>
3009
3010<!-- _______________________________________________________________________ -->
3011<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3012 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3013</div>
3014<div class="doc_text">
3015
3016<h5>Syntax:</h5>
3017<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3018 &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3019</pre>
3020
3021<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3022<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3023<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3024</p>
3025
3026
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3027<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3028<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3029<a href="#t_floating">floating point</a> value, and a type to cast it to, which
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3030must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3031
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3032<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3033<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3034<a href="#t_floating">floating point</a> operand into the nearest (rounding
3035towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3036the results are undefined.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3037
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3038<p>When converting to i1, the conversion is done as a comparison against
3039zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3040If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3041
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3042<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3043<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3044 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
3045 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3046 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3047</pre>
3048</div>
3049
3050<!-- _______________________________________________________________________ -->
3051<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3052 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3053</div>
3054<div class="doc_text">
3055
3056<h5>Syntax:</h5>
3057<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3058 &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3059</pre>
3060
3061<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3062<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3063integer and converts that value to the <tt>ty2</tt> type.</p>
3064
3065
3066<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3067<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be an
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3068<a href="#t_integer">integer</a> value, and a type to cast it to, which must
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3069be a <a href="#t_floating">floating point</a> type.</p>
3070
3071<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3072<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3073integer quantity and converts it to the corresponding floating point value. If
3074the value cannot fit in the floating point value, the results are undefined.</p>
3075
3076
3077<h5>Example:</h5>
3078<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3079 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3080 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3081</pre>
3082</div>
3083
3084<!-- _______________________________________________________________________ -->
3085<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3086 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3087</div>
3088<div class="doc_text">
3089
3090<h5>Syntax:</h5>
3091<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3092 &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3093</pre>
3094
3095<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3096<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3097integer and converts that value to the <tt>ty2</tt> type.</p>
3098
3099<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3100<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be an
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3101<a href="#t_integer">integer</a> value, and a type to cast it to, which must be
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3102a <a href="#t_floating">floating point</a> type.</p>
3103
3104<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3105<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3106integer quantity and converts it to the corresponding floating point value. If
3107the value cannot fit in the floating point value, the results are undefined.</p>
3108
3109<h5>Example:</h5>
3110<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3111 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3112 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3113</pre>
3114</div>
3115
3116<!-- _______________________________________________________________________ -->
3117<div class="doc_subsubsection">
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3118 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3119</div>
3120<div class="doc_text">
3121
3122<h5>Syntax:</h5>
3123<pre>
3124 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3125</pre>
3126
3127<h5>Overview:</h5>
3128<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3129the integer type <tt>ty2</tt>.</p>
3130
3131<h5>Arguments:</h5>
3132<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3133must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3134<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3135
3136<h5>Semantics:</h5>
3137<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3138<tt>ty2</tt> by interpreting the pointer value as an integer and either
3139truncating or zero extending that value to the size of the integer type. If
3140<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3141<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3142are the same size, then nothing is done (<i>no-op cast</i>).</p>
3143
3144<h5>Example:</h5>
3145<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3146 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3147 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3148</pre>
3149</div>
3150
3151<!-- _______________________________________________________________________ -->
3152<div class="doc_subsubsection">
3153 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3154</div>
3155<div class="doc_text">
3156
3157<h5>Syntax:</h5>
3158<pre>
3159 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3160</pre>
3161
3162<h5>Overview:</h5>
3163<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3164a pointer type, <tt>ty2</tt>.</p>
3165
3166<h5>Arguments:</h5>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3167<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3168value to cast, and a type to cast it to, which must be a
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]3169<a href="#t_pointer">pointer</a> type.
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3170
3171<h5>Semantics:</h5>
3172<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3173<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3174the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3175size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3176the size of a pointer then a zero extension is done. If they are the same size,
3177nothing is done (<i>no-op cast</i>).</p>
3178
3179<h5>Example:</h5>
3180<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3181 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3182 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3183 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3184</pre>
3185</div>
3186
3187<!-- _______________________________________________________________________ -->
3188<div class="doc_subsubsection">
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3189 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3190</div>
3191<div class="doc_text">
3192
3193<h5>Syntax:</h5>
3194<pre>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3195 &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3196</pre>
3197
3198<h5>Overview:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3199<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3200<tt>ty2</tt> without changing any bits.</p>
3201
3202<h5>Arguments:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3203<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3204a first class value, and a type to cast it to, which must also be a <a
3205 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencere3db84c2007-01-09 20:08:58 +0000[diff] [blame]3206and the destination type, <tt>ty2</tt>, must be identical. If the source
3207type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3208
3209<h5>Semantics:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3210<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3211<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3212this conversion. The conversion is done as if the <tt>value</tt> had been
3213stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3214converted to other pointer types with this instruction. To convert pointers to
3215other types, use the <a href="#i_inttoptr">inttoptr</a> or
3216<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3217
3218<h5>Example:</h5>
3219<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3220 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3221 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3222 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3223</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3224</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3225
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3226<!-- ======================================================================= -->
3227<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3228<div class="doc_text">
3229<p>The instructions in this category are the "miscellaneous"
3230instructions, which defy better classification.</p>
3231</div>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3232
3233<!-- _______________________________________________________________________ -->
3234<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3235</div>
3236<div class="doc_text">
3237<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3238<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3239<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3240</pre>
3241<h5>Overview:</h5>
3242<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3243of its two integer operands.</p>
3244<h5>Arguments:</h5>
3245<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3246the condition code which indicates the kind of comparison to perform. It is not
3247a value, just a keyword. The possibilities for the condition code are:
3248<ol>
3249 <li><tt>eq</tt>: equal</li>
3250 <li><tt>ne</tt>: not equal </li>
3251 <li><tt>ugt</tt>: unsigned greater than</li>
3252 <li><tt>uge</tt>: unsigned greater or equal</li>
3253 <li><tt>ult</tt>: unsigned less than</li>
3254 <li><tt>ule</tt>: unsigned less or equal</li>
3255 <li><tt>sgt</tt>: signed greater than</li>
3256 <li><tt>sge</tt>: signed greater or equal</li>
3257 <li><tt>slt</tt>: signed less than</li>
3258 <li><tt>sle</tt>: signed less or equal</li>
3259</ol>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3260<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3261<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3262<h5>Semantics:</h5>
3263<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3264the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3265yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3266<ol>
3267 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3268 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3269 </li>
3270 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3271 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3272 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3273 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3274 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3275 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3276 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3277 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3278 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3279 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3280 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3281 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3282 <li><tt>sge</tt>: interprets the operands as signed values and yields
3283 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3284 <li><tt>slt</tt>: interprets the operands as signed values and yields
3285 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3286 <li><tt>sle</tt>: interprets the operands as signed values and yields
3287 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3288</ol>
3289<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3290values are treated as integers and then compared.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3291
3292<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3293<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3294 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3295 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3296 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3297 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3298 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3299</pre>
3300</div>
3301
3302<!-- _______________________________________________________________________ -->
3303<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3304</div>
3305<div class="doc_text">
3306<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3307<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3308<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3309</pre>
3310<h5>Overview:</h5>
3311<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3312of its floating point operands.</p>
3313<h5>Arguments:</h5>
3314<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3315the condition code which indicates the kind of comparison to perform. It is not
3316a value, just a keyword. The possibilities for the condition code are:
3317<ol>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3318 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3319 <li><tt>oeq</tt>: ordered and equal</li>
3320 <li><tt>ogt</tt>: ordered and greater than </li>
3321 <li><tt>oge</tt>: ordered and greater than or equal</li>
3322 <li><tt>olt</tt>: ordered and less than </li>
3323 <li><tt>ole</tt>: ordered and less than or equal</li>
3324 <li><tt>one</tt>: ordered and not equal</li>
3325 <li><tt>ord</tt>: ordered (no nans)</li>
3326 <li><tt>ueq</tt>: unordered or equal</li>
3327 <li><tt>ugt</tt>: unordered or greater than </li>
3328 <li><tt>uge</tt>: unordered or greater than or equal</li>
3329 <li><tt>ult</tt>: unordered or less than </li>
3330 <li><tt>ule</tt>: unordered or less than or equal</li>
3331 <li><tt>une</tt>: unordered or not equal</li>
3332 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3333 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3334</ol>
Reid Spencer02e0d1d2006-12-06 07:08:07 +0000[diff] [blame]3335<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3336<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3337<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3338<a href="#t_floating">floating point</a> typed. They must have identical
3339types.</p>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3340<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3341<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3342<h5>Semantics:</h5>
3343<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3344the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3345yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3346<ol>
3347 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3348 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3349 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3350 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3351 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3352 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3353 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3354 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3355 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3356 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3357 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3358 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3359 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3360 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3361 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3362 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3363 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3364 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3365 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3366 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3367 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3368 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3369 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3370 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3371 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3372 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3373 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3374 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3375</ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3376
3377<h5>Example:</h5>
3378<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3379 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3380 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3381 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3382</pre>
3383</div>
3384
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3385<!-- _______________________________________________________________________ -->
3386<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3387Instruction</a> </div>
3388<div class="doc_text">
3389<h5>Syntax:</h5>
3390<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3391<h5>Overview:</h5>
3392<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3393the SSA graph representing the function.</p>
3394<h5>Arguments:</h5>
3395<p>The type of the incoming values are specified with the first type
3396field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3397as arguments, with one pair for each predecessor basic block of the
3398current block. Only values of <a href="#t_firstclass">first class</a>
3399type may be used as the value arguments to the PHI node. Only labels
3400may be used as the label arguments.</p>
3401<p>There must be no non-phi instructions between the start of a basic
3402block and the PHI instructions: i.e. PHI instructions must be first in
3403a basic block.</p>
3404<h5>Semantics:</h5>
3405<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3406value specified by the parameter, depending on which basic block we
3407came from in the last <a href="#terminators">terminator</a> instruction.</p>
3408<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3409<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add i32 %indvar, 1<br> br label %Loop<br></pre>
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3410</div>
3411
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3412<!-- _______________________________________________________________________ -->
3413<div class="doc_subsubsection">
3414 <a name="i_select">'<tt>select</tt>' Instruction</a>
3415</div>
3416
3417<div class="doc_text">
3418
3419<h5>Syntax:</h5>
3420
3421<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3422 &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3423</pre>
3424
3425<h5>Overview:</h5>
3426
3427<p>
3428The '<tt>select</tt>' instruction is used to choose one value based on a
3429condition, without branching.
3430</p>
3431
3432
3433<h5>Arguments:</h5>
3434
3435<p>
3436The '<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.
3437</p>
3438
3439<h5>Semantics:</h5>
3440
3441<p>
3442If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3443value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3444</p>
3445
3446<h5>Example:</h5>
3447
3448<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3449 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3450</pre>
3451</div>
3452
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]3453
3454<!-- _______________________________________________________________________ -->
3455<div class="doc_subsubsection">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3456 <a name="i_call">'<tt>call</tt>' Instruction</a>
3457</div>
3458
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3459<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3460
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3461<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3462<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3463 &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]3464</pre>
3465
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3466<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3467
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3468<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3469
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3470<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3471
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3472<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3473
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3474<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3475 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3476 <p>The optional "tail" marker indicates whether the callee function accesses
3477 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3478 function call is eligible for tail call optimization. Note that calls may
3479 be marked "tail" even if they do not occur before a <a
3480 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3481 </li>
3482 <li>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3483 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3484 convention</a> the call should use. If none is specified, the call defaults
3485 to using C calling conventions.
3486 </li>
3487 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3488 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3489 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3490 signature. This type can be omitted if the function is not varargs and
3491 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3492 </li>
3493 <li>
3494 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3495 be invoked. In most cases, this is a direct function invocation, but
3496 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3497 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3498 </li>
3499 <li>
3500 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]3501 function signature argument types. All arguments must be of
3502 <a href="#t_firstclass">first class</a> type. If the function signature
3503 indicates the function accepts a variable number of arguments, the extra
3504 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3505 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3506</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3507
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3508<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3509
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3510<p>The '<tt>call</tt>' instruction is used to cause control flow to
3511transfer to a specified function, with its incoming arguments bound to
3512the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3513instruction in the called function, control flow continues with the
3514instruction after the function call, and the return value of the
3515function is bound to the result argument. This is a simpler case of
3516the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3517
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3518<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3519
3520<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3521 %retval = call i32 %test(i32 %argc)
3522 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3523 %X = tail call i32 %foo()
3524 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3525</pre>
3526
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3527</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3528
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3529<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3530<div class="doc_subsubsection">
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3531 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3532</div>
3533
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3534<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3535
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3536<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3537
3538<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3539 &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]3540</pre>
3541
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3542<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3543
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3544<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3545the "variable argument" area of a function call. It is used to implement the
3546<tt>va_arg</tt> macro in C.</p>
3547
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3548<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3549
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3550<p>This instruction takes a <tt>va_list*</tt> value and the type of
3551the argument. It returns a value of the specified argument type and
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]3552increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3553actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3554
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3555<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3556
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3557<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3558type from the specified <tt>va_list</tt> and causes the
3559<tt>va_list</tt> to point to the next argument. For more information,
3560see the variable argument handling <a href="#int_varargs">Intrinsic
3561Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3562
3563<p>It is legal for this instruction to be called in a function which does not
3564take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3565function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3566
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3567<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3568href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3569argument.</p>
3570
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3571<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3572
3573<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3574
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3575</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3576
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3577<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3578<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3579<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3580
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3581<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3582
3583<p>LLVM supports the notion of an "intrinsic function". These functions have
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3584well known names and semantics and are required to follow certain restrictions.
3585Overall, these intrinsics represent an extension mechanism for the LLVM
3586language that does not require changing all of the transformations in LLVM to
3587add to the language (or the bytecode reader/writer, the parser,
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3588etc...).</p>
3589
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3590<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3591prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3592this. Intrinsic functions must always be external functions: you cannot define
3593the body of intrinsic functions. Intrinsic functions may only be used in call
3594or invoke instructions: it is illegal to take the address of an intrinsic
3595function. Additionally, because intrinsic functions are part of the LLVM
3596language, it is required that they all be documented here if any are added.</p>
3597
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3598<p>Some intrinsic functions can be overloaded. That is, the intrinsic represents
3599a family of functions that perform the same operation but on different data
3600types. This is most frequent with the integer types. Since LLVM can represent
3601over 8 million different integer types, there is a way to declare an intrinsic
3602that can be overloaded based on its arguments. Such intrinsics will have the
3603names of the arbitrary types encoded into the intrinsic function name, each
3604preceded by a period. For example, the <tt>llvm.ctpop</tt> function can take an
3605integer of any width. This leads to a family of functions such as
3606<tt>i32 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i32 @llvm.ctpop.i29(i29 %val)</tt>.
3607</p>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3608
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3609
3610<p>To learn how to add an intrinsic function, please see the
3611<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3612</p>
3613
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3614</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3615
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3616<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3617<div class="doc_subsection">
3618 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3619</div>
3620
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3621<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3622
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3623<p>Variable argument support is defined in LLVM with the <a
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3624 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3625intrinsic functions. These functions are related to the similarly
3626named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3627
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3628<p>All of these functions operate on arguments that use a
3629target-specific value type "<tt>va_list</tt>". The LLVM assembly
3630language reference manual does not define what this type is, so all
3631transformations should be prepared to handle intrinsics with any type
3632used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3633
Chris Lattner30b868d2006-05-15 17:26:46 +0000[diff] [blame]3634<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]3635instruction and the variable argument handling intrinsic functions are
3636used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3637
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3638<pre>
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3639define i32 @test(i32 %X, ...) {
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3640 ; Initialize variable argument processing
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3641 %ap = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3642 %ap2 = bitcast i8** %ap to i8*
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3643 call void @llvm.va_start(i8* %ap2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3644
3645 ; Read a single integer argument
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3646 %tmp = va_arg i8 ** %ap, i32
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3647
3648 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3649 %aq = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3650 %aq2 = bitcast i8** %aq to i8*
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3651 call void @llvm.va_copy(i8 *%aq2, i8* %ap2)
3652 call void @llvm.va_end(i8* %aq2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3653
3654 ; Stop processing of arguments.
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3655 call void @llvm.va_end(i8* %ap2)
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3656 ret i32 %tmp
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3657}
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3658
3659declare void @llvm.va_start(i8*)
3660declare void @llvm.va_copy(i8*, i8*)
3661declare void @llvm.va_end(i8*)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3662</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3663</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3664
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3665<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3666<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3667 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3668</div>
3669
3670
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3671<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3672<h5>Syntax:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3673<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3674<h5>Overview:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3675<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3676<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3677href="#i_va_arg">va_arg</a></tt>.</p>
3678
3679<h5>Arguments:</h5>
3680
3681<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3682
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3683<h5>Semantics:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3684
3685<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3686macro available in C. In a target-dependent way, it initializes the
3687<tt>va_list</tt> element the argument points to, so that the next call to
3688<tt>va_arg</tt> will produce the first variable argument passed to the function.
3689Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3690last argument of the function, the compiler can figure that out.</p>
3691
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3692</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3693
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3694<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3695<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3696 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3697</div>
3698
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3699<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3700<h5>Syntax:</h5>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3701<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3702<h5>Overview:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3703
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3704<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3705which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3706or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3707
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3708<h5>Arguments:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3709
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3710<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3711
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3712<h5>Semantics:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3713
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3714<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]3715macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3716Calls to <a href="#int_va_start"><tt>llvm.va_start</tt></a> and <a
3717 href="#int_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3718with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3719
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3720</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3721
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3722<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3723<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3724 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3725</div>
3726
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3727<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3728
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3729<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3730
3731<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3732 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3733</pre>
3734
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3735<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3736
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3737<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3738the source argument list to the destination argument list.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3739
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3740<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3741
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3742<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]3743The 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]3744
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3745
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3746<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3747
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3748<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3749available in C. In a target-dependent way, it copies the source
3750<tt>va_list</tt> element into the destination list. This intrinsic is necessary
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3751because the <tt><a href="#int_va_start">llvm.va_start</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3752arbitrarily complex and require memory allocation, for example.</p>
3753
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3754</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3755
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3756<!-- ======================================================================= -->
3757<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3758 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3759</div>
3760
3761<div class="doc_text">
3762
3763<p>
3764LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3765Collection</a> requires the implementation and generation of these intrinsics.
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3766These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3767stack</a>, as well as garbage collector implementations that require <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3768href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3769Front-ends for type-safe garbage collected languages should generate these
3770intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3771href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3772</p>
3773</div>
3774
3775<!-- _______________________________________________________________________ -->
3776<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3777 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3778</div>
3779
3780<div class="doc_text">
3781
3782<h5>Syntax:</h5>
3783
3784<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3785 declare void @llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3786</pre>
3787
3788<h5>Overview:</h5>
3789
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]3790<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]3791the code generator, and allows some metadata to be associated with it.</p>
3792
3793<h5>Arguments:</h5>
3794
3795<p>The first argument specifies the address of a stack object that contains the
3796root pointer. The second pointer (which must be either a constant or a global
3797value address) contains the meta-data to be associated with the root.</p>
3798
3799<h5>Semantics:</h5>
3800
3801<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3802location. At compile-time, the code generator generates information to allow
3803the runtime to find the pointer at GC safe points.
3804</p>
3805
3806</div>
3807
3808
3809<!-- _______________________________________________________________________ -->
3810<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3811 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3812</div>
3813
3814<div class="doc_text">
3815
3816<h5>Syntax:</h5>
3817
3818<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3819 declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3820</pre>
3821
3822<h5>Overview:</h5>
3823
3824<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3825locations, allowing garbage collector implementations that require read
3826barriers.</p>
3827
3828<h5>Arguments:</h5>
3829
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3830<p>The second argument is the address to read from, which should be an address
3831allocated from the garbage collector. The first object is a pointer to the
3832start of the referenced object, if needed by the language runtime (otherwise
3833null).</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3834
3835<h5>Semantics:</h5>
3836
3837<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3838instruction, but may be replaced with substantially more complex code by the
3839garbage collector runtime, as needed.</p>
3840
3841</div>
3842
3843
3844<!-- _______________________________________________________________________ -->
3845<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3846 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3847</div>
3848
3849<div class="doc_text">
3850
3851<h5>Syntax:</h5>
3852
3853<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3854 declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3855</pre>
3856
3857<h5>Overview:</h5>
3858
3859<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3860locations, allowing garbage collector implementations that require write
3861barriers (such as generational or reference counting collectors).</p>
3862
3863<h5>Arguments:</h5>
3864
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3865<p>The first argument is the reference to store, the second is the start of the
3866object to store it to, and the third is the address of the field of Obj to
3867store to. If the runtime does not require a pointer to the object, Obj may be
3868null.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3869
3870<h5>Semantics:</h5>
3871
3872<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3873instruction, but may be replaced with substantially more complex code by the
3874garbage collector runtime, as needed.</p>
3875
3876</div>
3877
3878
3879
3880<!-- ======================================================================= -->
3881<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3882 <a name="int_codegen">Code Generator Intrinsics</a>
3883</div>
3884
3885<div class="doc_text">
3886<p>
3887These intrinsics are provided by LLVM to expose special features that may only
3888be implemented with code generator support.
3889</p>
3890
3891</div>
3892
3893<!-- _______________________________________________________________________ -->
3894<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3895 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3896</div>
3897
3898<div class="doc_text">
3899
3900<h5>Syntax:</h5>
3901<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3902 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3903</pre>
3904
3905<h5>Overview:</h5>
3906
3907<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3908The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3909target-specific value indicating the return address of the current function
3910or one of its callers.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3911</p>
3912
3913<h5>Arguments:</h5>
3914
3915<p>
3916The argument to this intrinsic indicates which function to return the address
3917for. Zero indicates the calling function, one indicates its caller, etc. The
3918argument is <b>required</b> to be a constant integer value.
3919</p>
3920
3921<h5>Semantics:</h5>
3922
3923<p>
3924The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3925the return address of the specified call frame, or zero if it cannot be
3926identified. The value returned by this intrinsic is likely to be incorrect or 0
3927for arguments other than zero, so it should only be used for debugging purposes.
3928</p>
3929
3930<p>
3931Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3932aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3933source-language caller.
3934</p>
3935</div>
3936
3937
3938<!-- _______________________________________________________________________ -->
3939<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3940 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3941</div>
3942
3943<div class="doc_text">
3944
3945<h5>Syntax:</h5>
3946<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3947 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3948</pre>
3949
3950<h5>Overview:</h5>
3951
3952<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3953The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3954target-specific frame pointer value for the specified stack frame.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3955</p>
3956
3957<h5>Arguments:</h5>
3958
3959<p>
3960The argument to this intrinsic indicates which function to return the frame
3961pointer for. Zero indicates the calling function, one indicates its caller,
3962etc. The argument is <b>required</b> to be a constant integer value.
3963</p>
3964
3965<h5>Semantics:</h5>
3966
3967<p>
3968The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3969the frame address of the specified call frame, or zero if it cannot be
3970identified. The value returned by this intrinsic is likely to be incorrect or 0
3971for arguments other than zero, so it should only be used for debugging purposes.
3972</p>
3973
3974<p>
3975Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3976aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3977source-language caller.
3978</p>
3979</div>
3980
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3981<!-- _______________________________________________________________________ -->
3982<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3983 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3984</div>
3985
3986<div class="doc_text">
3987
3988<h5>Syntax:</h5>
3989<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3990 declare i8 *@llvm.stacksave()
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3991</pre>
3992
3993<h5>Overview:</h5>
3994
3995<p>
3996The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]3997the function stack, for use with <a href="#int_stackrestore">
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3998<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3999features like scoped automatic variable sized arrays in C99.
4000</p>
4001
4002<h5>Semantics:</h5>
4003
4004<p>
4005This intrinsic returns a opaque pointer value that can be passed to <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4006href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4007<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4008<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4009state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4010practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4011that were allocated after the <tt>llvm.stacksave</tt> was executed.
4012</p>
4013
4014</div>
4015
4016<!-- _______________________________________________________________________ -->
4017<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4018 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4019</div>
4020
4021<div class="doc_text">
4022
4023<h5>Syntax:</h5>
4024<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4025 declare void @llvm.stackrestore(i8 * %ptr)
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4026</pre>
4027
4028<h5>Overview:</h5>
4029
4030<p>
4031The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4032the function stack to the state it was in when the corresponding <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4033href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4034useful for implementing language features like scoped automatic variable sized
4035arrays in C99.
4036</p>
4037
4038<h5>Semantics:</h5>
4039
4040<p>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4041See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4042</p>
4043
4044</div>
4045
4046
4047<!-- _______________________________________________________________________ -->
4048<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4049 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4050</div>
4051
4052<div class="doc_text">
4053
4054<h5>Syntax:</h5>
4055<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4056 declare void @llvm.prefetch(i8 * &lt;address&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4057 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4058</pre>
4059
4060<h5>Overview:</h5>
4061
4062
4063<p>
4064The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4065a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4066no
4067effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]4068characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4069</p>
4070
4071<h5>Arguments:</h5>
4072
4073<p>
4074<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4075determining if the fetch should be for a read (0) or write (1), and
4076<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]4077locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4078<tt>locality</tt> arguments must be constant integers.
4079</p>
4080
4081<h5>Semantics:</h5>
4082
4083<p>
4084This intrinsic does not modify the behavior of the program. In particular,
4085prefetches cannot trap and do not produce a value. On targets that support this
4086intrinsic, the prefetch can provide hints to the processor cache for better
4087performance.
4088</p>
4089
4090</div>
4091
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4092<!-- _______________________________________________________________________ -->
4093<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4094 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4095</div>
4096
4097<div class="doc_text">
4098
4099<h5>Syntax:</h5>
4100<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4101 declare void @llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4102</pre>
4103
4104<h5>Overview:</h5>
4105
4106
4107<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4108The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4109(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4110code to simulators and other tools. The method is target specific, but it is
4111expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]4112The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnere64d41d2005-11-15 06:07:55 +0000[diff] [blame]4113after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb40261e2006-03-24 07:16:10 +0000[diff] [blame]4114optimizations. The intended use is to be inserted after optimizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4115correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4116</p>
4117
4118<h5>Arguments:</h5>
4119
4120<p>
4121<tt>id</tt> is a numerical id identifying the marker.
4122</p>
4123
4124<h5>Semantics:</h5>
4125
4126<p>
4127This intrinsic does not modify the behavior of the program. Backends that do not
4128support this intrinisic may ignore it.
4129</p>
4130
4131</div>
4132
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4133<!-- _______________________________________________________________________ -->
4134<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4135 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4136</div>
4137
4138<div class="doc_text">
4139
4140<h5>Syntax:</h5>
4141<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4142 declare i64 @llvm.readcyclecounter( )
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4143</pre>
4144
4145<h5>Overview:</h5>
4146
4147
4148<p>
4149The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4150counter register (or similar low latency, high accuracy clocks) on those targets
4151that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4152As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4153should only be used for small timings.
4154</p>
4155
4156<h5>Semantics:</h5>
4157
4158<p>
4159When directly supported, reading the cycle counter should not modify any memory.
4160Implementations are allowed to either return a application specific value or a
4161system wide value. On backends without support, this is lowered to a constant 0.
4162</p>
4163
4164</div>
4165
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4166<!-- ======================================================================= -->
4167<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4168 <a name="int_libc">Standard C Library Intrinsics</a>
4169</div>
4170
4171<div class="doc_text">
4172<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4173LLVM provides intrinsics for a few important standard C library functions.
4174These intrinsics allow source-language front-ends to pass information about the
4175alignment of the pointer arguments to the code generator, providing opportunity
4176for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4177</p>
4178
4179</div>
4180
4181<!-- _______________________________________________________________________ -->
4182<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4183 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4184</div>
4185
4186<div class="doc_text">
4187
4188<h5>Syntax:</h5>
4189<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4190 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4191 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4192 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4193 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4194</pre>
4195
4196<h5>Overview:</h5>
4197
4198<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4199The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4200location to the destination location.
4201</p>
4202
4203<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4204Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4205intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4206</p>
4207
4208<h5>Arguments:</h5>
4209
4210<p>
4211The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4212the source. The third argument is an integer argument
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4213specifying the number of bytes to copy, and the fourth argument is the alignment
4214of the source and destination locations.
4215</p>
4216
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4217<p>
4218If 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]4219the caller guarantees that both the source and destination pointers are aligned
4220to that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4221</p>
4222
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4223<h5>Semantics:</h5>
4224
4225<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4226The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4227location to the destination location, which are not allowed to overlap. It
4228copies "len" bytes of memory over. If the argument is known to be aligned to
4229some boundary, this can be specified as the fourth argument, otherwise it should
4230be set to 0 or 1.
4231</p>
4232</div>
4233
4234
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4235<!-- _______________________________________________________________________ -->
4236<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4237 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4238</div>
4239
4240<div class="doc_text">
4241
4242<h5>Syntax:</h5>
4243<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4244 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4245 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4246 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4247 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4248</pre>
4249
4250<h5>Overview:</h5>
4251
4252<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4253The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4254location to the destination location. It is similar to the
4255'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4256</p>
4257
4258<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4259Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4260intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4261</p>
4262
4263<h5>Arguments:</h5>
4264
4265<p>
4266The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4267the source. The third argument is an integer argument
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4268specifying the number of bytes to copy, and the fourth argument is the alignment
4269of the source and destination locations.
4270</p>
4271
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4272<p>
4273If 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]4274the caller guarantees that the source and destination pointers are aligned to
4275that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4276</p>
4277
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4278<h5>Semantics:</h5>
4279
4280<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4281The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4282location to the destination location, which may overlap. It
4283copies "len" bytes of memory over. If the argument is known to be aligned to
4284some boundary, this can be specified as the fourth argument, otherwise it should
4285be set to 0 or 1.
4286</p>
4287</div>
4288
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4289
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4290<!-- _______________________________________________________________________ -->
4291<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4292 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4293</div>
4294
4295<div class="doc_text">
4296
4297<h5>Syntax:</h5>
4298<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4299 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4300 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4301 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4302 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4303</pre>
4304
4305<h5>Overview:</h5>
4306
4307<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4308The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4309byte value.
4310</p>
4311
4312<p>
4313Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4314does not return a value, and takes an extra alignment argument.
4315</p>
4316
4317<h5>Arguments:</h5>
4318
4319<p>
4320The first argument is a pointer to the destination to fill, the second is the
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4321byte value to fill it with, the third argument is an integer
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4322argument specifying the number of bytes to fill, and the fourth argument is the
4323known alignment of destination location.
4324</p>
4325
4326<p>
4327If 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]4328the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4329</p>
4330
4331<h5>Semantics:</h5>
4332
4333<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4334The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4335the
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4336destination location. If the argument is known to be aligned to some boundary,
4337this can be specified as the fourth argument, otherwise it should be set to 0 or
43381.
4339</p>
4340</div>
4341
4342
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4343<!-- _______________________________________________________________________ -->
4344<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4345 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4346</div>
4347
4348<div class="doc_text">
4349
4350<h5>Syntax:</h5>
4351<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4352 declare float @llvm.sqrt.f32(float %Val)
4353 declare double @llvm.sqrt.f64(double %Val)
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4354</pre>
4355
4356<h5>Overview:</h5>
4357
4358<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4359The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4360returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4361<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4362negative numbers (which allows for better optimization).
4363</p>
4364
4365<h5>Arguments:</h5>
4366
4367<p>
4368The argument and return value are floating point numbers of the same type.
4369</p>
4370
4371<h5>Semantics:</h5>
4372
4373<p>
4374This function returns the sqrt of the specified operand if it is a positive
4375floating point number.
4376</p>
4377</div>
4378
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4379<!-- _______________________________________________________________________ -->
4380<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4381 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4382</div>
4383
4384<div class="doc_text">
4385
4386<h5>Syntax:</h5>
4387<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4388 declare float @llvm.powi.f32(float %Val, i32 %power)
4389 declare double @llvm.powi.f64(double %Val, i32 %power)
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4390</pre>
4391
4392<h5>Overview:</h5>
4393
4394<p>
4395The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4396specified (positive or negative) power. The order of evaluation of
4397multiplications is not defined.
4398</p>
4399
4400<h5>Arguments:</h5>
4401
4402<p>
4403The second argument is an integer power, and the first is a value to raise to
4404that power.
4405</p>
4406
4407<h5>Semantics:</h5>
4408
4409<p>
4410This function returns the first value raised to the second power with an
4411unspecified sequence of rounding operations.</p>
4412</div>
4413
4414
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4415<!-- ======================================================================= -->
4416<div class="doc_subsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4417 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4418</div>
4419
4420<div class="doc_text">
4421<p>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4422LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4423These allow efficient code generation for some algorithms.
4424</p>
4425
4426</div>
4427
4428<!-- _______________________________________________________________________ -->
4429<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4430 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4431</div>
4432
4433<div class="doc_text">
4434
4435<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4436<p>This is an overloaded intrinsic function. You can use bswap on any integer
4437type that is an even number of bytes (i.e. BitWidth % 16 == 0). Note the suffix
4438that includes the type for the result and the operand.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4439<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4440 declare i16 @llvm.bswap.i16.i16(i16 &lt;id&gt;)
4441 declare i32 @llvm.bswap.i32.i32(i32 &lt;id&gt;)
Reid Spencer403a1c42007-04-02 00:19:52 +0000[diff] [blame]4442 declare i64 @llvm.bswap.i64.i64(i64 &lt;id&gt;)
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4443</pre>
4444
4445<h5>Overview:</h5>
4446
4447<p>
Reid Spencerf361c4f2007-04-02 02:25:19 +0000[diff] [blame]4448The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4449values with an even number of bytes (positive multiple of 16 bits). These are
4450useful for performing operations on data that is not in the target's native
4451byte order.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4452</p>
4453
4454<h5>Semantics:</h5>
4455
4456<p>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4457The <tt>llvm.bswap.16.i16</tt> intrinsic returns an i16 value that has the high
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4458and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4459intrinsic returns an i32 value that has the four bytes of the input i32
4460swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4461i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48.i48</tt>,
4462<tt>llvm.bswap.i64.i64</tt> and other intrinsics extend this concept to
4463additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4464</p>
4465
4466</div>
4467
4468<!-- _______________________________________________________________________ -->
4469<div class="doc_subsubsection">
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4470 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4471</div>
4472
4473<div class="doc_text">
4474
4475<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4476<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4477width. Not all targets support all bit widths however.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4478<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4479 declare i32 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4480 declare i32 @llvm.ctpop.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4481 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4482 declare i32 @llvm.ctpop.i64(i64 &lt;src&gt;)
4483 declare i32 @llvm.ctpop.i256(i256 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4484</pre>
4485
4486<h5>Overview:</h5>
4487
4488<p>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]4489The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4490value.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4491</p>
4492
4493<h5>Arguments:</h5>
4494
4495<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4496The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4497integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4498</p>
4499
4500<h5>Semantics:</h5>
4501
4502<p>
4503The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4504</p>
4505</div>
4506
4507<!-- _______________________________________________________________________ -->
4508<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4509 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4510</div>
4511
4512<div class="doc_text">
4513
4514<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4515<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4516integer bit width. Not all targets support all bit widths however.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4517<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4518 declare i32 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4519 declare i32 @llvm.ctlz.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4520 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4521 declare i32 @llvm.ctlz.i64(i64 &lt;src&gt;)
4522 declare i32 @llvm.ctlz.i256(i256 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4523</pre>
4524
4525<h5>Overview:</h5>
4526
4527<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4528The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4529leading zeros in a variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4530</p>
4531
4532<h5>Arguments:</h5>
4533
4534<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4535The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4536integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4537</p>
4538
4539<h5>Semantics:</h5>
4540
4541<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4542The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4543in a variable. If the src == 0 then the result is the size in bits of the type
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4544of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4545</p>
4546</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4547
4548
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4549
4550<!-- _______________________________________________________________________ -->
4551<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4552 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4553</div>
4554
4555<div class="doc_text">
4556
4557<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4558<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4559integer bit width. Not all targets support all bit widths however.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4560<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4561 declare i32 @llvm.cttz.i8 (i8 &lt;src&gt;)
4562 declare i32 @llvm.cttz.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4563 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4564 declare i32 @llvm.cttz.i64(i64 &lt;src&gt;)
4565 declare i32 @llvm.cttz.i256(i256 &lt;src&gt;)
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4566</pre>
4567
4568<h5>Overview:</h5>
4569
4570<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4571The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4572trailing zeros.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4573</p>
4574
4575<h5>Arguments:</h5>
4576
4577<p>
4578The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4579integer type. The return type must match the argument type.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4580</p>
4581
4582<h5>Semantics:</h5>
4583
4584<p>
4585The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4586in a variable. If the src == 0 then the result is the size in bits of the type
4587of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4588</p>
4589</div>
4590
Reid Spencer8a5799f2007-04-01 08:27:01 +0000[diff] [blame]4591<!-- _______________________________________________________________________ -->
4592<div class="doc_subsubsection">
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4593 <a name="int_bit_part_select">'<tt>llvm.bit.part.select.*</tt>' Intrinsic</a>
4594</div>
4595
4596<div class="doc_text">
4597
4598<h5>Syntax:</h5>
4599<p>This is an overloaded intrinsic. You can use <tt>llvm.bit.part.select</tt>
4600on any integer bit width.
4601<pre>
4602 declare i17 @llvm.bit.part.select.i17.i17 (i17 %val, i32 %loBit, i32 %hiBit)
4603 declare i29 @llvm.bit.part.select.i29.i29 (i29 %val, i32 %loBit, i32 %hiBit)
4604</pre>
4605
4606<h5>Overview:</h5>
4607<p>The '<tt>llvm.bit.part.select</tt>' family of intrinsic functions selects a
4608range of bits from an integer value and returns them in the same bit width as
4609the original value.</p>
4610
4611<h5>Arguments:</h5>
4612<p>The first argument, <tt>%val</tt> and the result may be integer types of
4613any bit width but they must have the same bit width. The second and third
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4614arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4615
4616<h5>Semantics:</h5>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4617<p>The operation of the '<tt>llvm.bit.part.select</tt>' intrinsic has two modes
4618of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
4619<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
4620operates in forward mode.</p>
4621<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
4622right by <tt>%loBit</tt> bits and then ANDing it with a mask with
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4623only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
4624<ol>
4625 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
4626 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
4627 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
4628 to determine the number of bits to retain.</li>
4629 <li>A mask of the retained bits is created by shifting a -1 value.</li>
4630 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
4631</ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame^]4632<p>In reverse mode, a similar computation is made except that:</p>
4633<ol>
4634 <li>The bits selected wrap around to include both the highest and lowest bits.
4635 For example, part_select(i16 X, 4, 7) selects bits from X with a mask of
4636 0x00F0 (forwards case) while part_select(i16 X, 8, 3) selects bits from X
4637 with a mask of 0xFF0F.</li>
4638 <li>The bits returned in the reverse case are reversed. So, if X has the value
4639 0x6ACF and we apply part_select(i16 X, 8, 3) to it, we get back the value
4640 0x0A6F.</li>
4641</ol>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4642</div>
4643
4644<!-- _______________________________________________________________________ -->
4645<div class="doc_subsubsection">
4646 <a name="int_bit_part_set">'<tt>llvm.bit.part.set.*</tt>' Intrinsic</a>
4647</div>
4648
4649<div class="doc_text">
4650
4651<h5>Syntax:</h5>
4652<p>This is an overloaded intrinsic. You can use <tt>llvm.bit.part.set</tt> on
4653any integer bit width.
4654<pre>
4655 declare i17 @llvm.bit.part.set.i17.i17.i9 (i17 %val, i32 %bit, i9 %newbits)
4656 declare i29 @llvm.bit.part.set.i29.i29.i13(i29 %val, i32 %bit, i13 %newbits)
4657</pre>
4658
4659<h5>Overview:</h5>
4660<p>The '<tt>llvm.bit.part.set</tt>' family of intrinsic functions sets a range
4661of bits in a given value to a new value and returns the result.</p>
4662
4663<h5>Arguments:</h5>
4664<p>The first argument and the result may be an integer type of any bit width but
4665they must have the same bit width. The second argument must be an <tt>i32</tt>.
4666The third argument may be any any bit width less than or equal to the bit width
4667of the first argument.</p>
4668
4669<h5>Semantics:</h5>
4670<p>The '<tt>llvm.bit.part.set</tt>' intrinsic sets the value given by
4671<tt>%newbits</tt> into <tt>%val</tt> at the bit index given by <tt>%bit</tt>.
4672This is equivalent to the following sequence:</p>
4673<ol>
4674 <li>The bits in <tt>%val</tt> starting at <tt>%bit</tt> and up to the width
4675 of <tt>%newbits</tt> are cleared by ANDing them with a zero mask.</li>
4676 <li>The bits in <tt>%newbits</tt> are shifted left by <tt>%bit</tt> bits.
4677 <li>The shifted <tt>%newbits</tt> value is OR'd into <tt>%val</tt> to produce
4678 the result.</li>
4679</ol>
4680</div>
4681
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4682<!-- ======================================================================= -->
4683<div class="doc_subsection">
4684 <a name="int_debugger">Debugger Intrinsics</a>
4685</div>
4686
4687<div class="doc_text">
4688<p>
4689The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4690are described in the <a
4691href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4692Debugging</a> document.
4693</p>
4694</div>
4695
4696
Jim Laskey2211f492007-03-14 19:31:19 +0000[diff] [blame]4697<!-- ======================================================================= -->
4698<div class="doc_subsection">
4699 <a name="int_eh">Exception Handling Intrinsics</a>
4700</div>
4701
4702<div class="doc_text">
4703<p> The LLVM exception handling intrinsics (which all start with
4704<tt>llvm.eh.</tt> prefix), are described in the <a
4705href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
4706Handling</a> document. </p>
4707</div>
4708
4709
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4710<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4711<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4712<address>
4713 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4714 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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4717
4718 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +0000[diff] [blame]4719 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4720 Last modified: $Date$
4721</address>
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4723</html>