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gerrit-public.fairphone.software / toolchain / llvm-project / 5bf54c868bbd8635cc0ebfe8e20c847b603154ce / . / llvm / docs / LangRef.html
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5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
8 <meta name="description"
9 content="LLVM Assembly Language Reference Manual.">
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11</head>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]12
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]13<body>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]14
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]15<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]16<ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]20 <li><a href="#highlevel">High Level Structure</a>
21 <ol>
22 <li><a href="#modulestructure">Module Structure</a></li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]23 <li><a href="#linkage">Linkage Types</a></li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]24 <li><a href="#callingconv">Calling Conventions</a></li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]25 <li><a href="#globalvars">Global Variables</a></li>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]26 <li><a href="#functionstructure">Functions</a></li>
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 Spencer5bf54c82007-04-11 23:23:49 +0000[diff] [blame^]187 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
188 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]189 </ol>
190 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]191 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Jim Laskey2211f492007-03-14 19:31:19 +0000[diff] [blame]192 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]193 </ol>
194 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]195</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]196
197<div class="doc_author">
198 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
199 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]200</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]201
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]202<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]203<div class="doc_section"> <a name="abstract">Abstract </a></div>
204<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]205
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]206<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]207<p>This document is a reference manual for the LLVM assembly language.
208LLVM is an SSA based representation that provides type safety,
209low-level operations, flexibility, and the capability of representing
210'all' high-level languages cleanly. It is the common code
211representation used throughout all phases of the LLVM compilation
212strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]213</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]214
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]215<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]216<div class="doc_section"> <a name="introduction">Introduction</a> </div>
217<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]218
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]219<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]220
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]221<p>The LLVM code representation is designed to be used in three
222different forms: as an in-memory compiler IR, as an on-disk bytecode
223representation (suitable for fast loading by a Just-In-Time compiler),
224and as a human readable assembly language representation. This allows
225LLVM to provide a powerful intermediate representation for efficient
226compiler transformations and analysis, while providing a natural means
227to debug and visualize the transformations. The three different forms
228of LLVM are all equivalent. This document describes the human readable
229representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]230
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]231<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]232while being expressive, typed, and extensible at the same time. It
233aims to be a "universal IR" of sorts, by being at a low enough level
234that high-level ideas may be cleanly mapped to it (similar to how
235microprocessors are "universal IR's", allowing many source languages to
236be mapped to them). By providing type information, LLVM can be used as
237the target of optimizations: for example, through pointer analysis, it
238can be proven that a C automatic variable is never accessed outside of
239the current function... allowing it to be promoted to a simple SSA
240value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]241
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]242</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]243
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]244<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]245<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]246
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]247<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]248
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]249<p>It is important to note that this document describes 'well formed'
250LLVM assembly language. There is a difference between what the parser
251accepts and what is considered 'well formed'. For example, the
252following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]253
254<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]255 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]256</pre>
257
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]258<p>...because the definition of <tt>%x</tt> does not dominate all of
259its uses. The LLVM infrastructure provides a verification pass that may
260be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]261automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]262the optimizer before it outputs bytecode. The violations pointed out
263by the verifier pass indicate bugs in transformation passes or input to
264the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]265
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]266<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]267
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]268<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]269<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]270<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]271
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]272<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]273
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]274<p>LLVM uses three different forms of identifiers, for different
275purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]276
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]277<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]278 <li>Named values are represented as a string of characters with a '%' prefix.
279 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
280 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
281 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]282 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]283 in a name.</li>
284
285 <li>Unnamed values are represented as an unsigned numeric value with a '%'
286 prefix. For example, %12, %2, %44.</li>
287
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]288 <li>Constants, which are described in a <a href="#constants">section about
289 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]290</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]291
292<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
293don't need to worry about name clashes with reserved words, and the set of
294reserved words may be expanded in the future without penalty. Additionally,
295unnamed identifiers allow a compiler to quickly come up with a temporary
296variable without having to avoid symbol table conflicts.</p>
297
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]298<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]299languages. There are keywords for different opcodes
300('<tt><a href="#i_add">add</a></tt>',
301 '<tt><a href="#i_bitcast">bitcast</a></tt>',
302 '<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]303href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]304and others. These reserved words cannot conflict with variable names, because
305none of them start with a '%' character.</p>
306
307<p>Here is an example of LLVM code to multiply the integer variable
308'<tt>%X</tt>' by 8:</p>
309
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]310<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]311
312<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]313 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]314</pre>
315
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]316<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]317
318<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]319 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]320</pre>
321
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]322<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]323
324<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]325 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
326 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
327 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]328</pre>
329
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]330<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
331important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]332
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]333<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]334
335 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
336 line.</li>
337
338 <li>Unnamed temporaries are created when the result of a computation is not
339 assigned to a named value.</li>
340
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]341 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]342
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]343</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]344
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]345<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]346demonstrating instructions, we will follow an instruction with a comment that
347defines the type and name of value produced. Comments are shown in italic
348text.</p>
349
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]350</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]351
352<!-- *********************************************************************** -->
353<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
354<!-- *********************************************************************** -->
355
356<!-- ======================================================================= -->
357<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
358</div>
359
360<div class="doc_text">
361
362<p>LLVM programs are composed of "Module"s, each of which is a
363translation unit of the input programs. Each module consists of
364functions, global variables, and symbol table entries. Modules may be
365combined together with the LLVM linker, which merges function (and
366global variable) definitions, resolves forward declarations, and merges
367symbol table entries. Here is an example of the "hello world" module:</p>
368
369<pre><i>; Declare the string constant as a global constant...</i>
370<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]371 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]372
373<i>; External declaration of the puts function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]374<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]375
376<i>; Definition of main function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]377define i32 %main() { <i>; i32()* </i>
378 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]379 %cast210 = <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]380 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]381
382 <i>; Call puts function to write out the string to stdout...</i>
383 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]384 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]385 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]386 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]387
388<p>This example is made up of a <a href="#globalvars">global variable</a>
389named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
390function, and a <a href="#functionstructure">function definition</a>
391for "<tt>main</tt>".</p>
392
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]393<p>In general, a module is made up of a list of global values,
394where both functions and global variables are global values. Global values are
395represented by a pointer to a memory location (in this case, a pointer to an
396array of char, and a pointer to a function), and have one of the following <a
397href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]398
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]399</div>
400
401<!-- ======================================================================= -->
402<div class="doc_subsection">
403 <a name="linkage">Linkage Types</a>
404</div>
405
406<div class="doc_text">
407
408<p>
409All Global Variables and Functions have one of the following types of linkage:
410</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]411
412<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]413
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]414 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]415
416 <dd>Global values with internal linkage are only directly accessible by
417 objects in the current module. In particular, linking code into a module with
418 an internal global value may cause the internal to be renamed as necessary to
419 avoid collisions. Because the symbol is internal to the module, all
420 references can be updated. This corresponds to the notion of the
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]421 '<tt>static</tt>' keyword in C.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]422 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]423
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]424 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]425
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]426 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
427 the same name when linkage occurs. This is typically used to implement
428 inline functions, templates, or other code which must be generated in each
429 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
430 allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]431 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]432
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]433 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]434
435 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
436 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]437 used for globals that may be emitted in multiple translation units, but that
438 are not guaranteed to be emitted into every translation unit that uses them.
439 One example of this are common globals in C, such as "<tt>int X;</tt>" at
440 global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]441 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]442
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]443 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]444
445 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
446 pointer to array type. When two global variables with appending linkage are
447 linked together, the two global arrays are appended together. This is the
448 LLVM, typesafe, equivalent of having the system linker append together
449 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]450 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]451
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]452 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
453 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
454 until linked, if not linked, the symbol becomes null instead of being an
455 undefined reference.
456 </dd>
457</dl>
458
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]459 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]460
461 <dd>If none of the above identifiers are used, the global is externally
462 visible, meaning that it participates in linkage and can be used to resolve
463 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]464 </dd>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]465
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]466 <p>
467 The next two types of linkage are targeted for Microsoft Windows platform
468 only. They are designed to support importing (exporting) symbols from (to)
469 DLLs.
470 </p>
471
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]472 <dl>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]473 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
474
475 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
476 or variable via a global pointer to a pointer that is set up by the DLL
477 exporting the symbol. On Microsoft Windows targets, the pointer name is
478 formed by combining <code>_imp__</code> and the function or variable name.
479 </dd>
480
481 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
482
483 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
484 pointer to a pointer in a DLL, so that it can be referenced with the
485 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
486 name is formed by combining <code>_imp__</code> and the function or variable
487 name.
488 </dd>
489
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]490</dl>
491
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]492<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]493variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
494variable and was linked with this one, one of the two would be renamed,
495preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
496external (i.e., lacking any linkage declarations), they are accessible
Reid Spencer92c671e2007-01-05 00:59:10 +0000[diff] [blame]497outside of the current module.</p>
498<p>It is illegal for a function <i>declaration</i>
499to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]500or <tt>extern_weak</tt>.</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]501
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]502</div>
503
504<!-- ======================================================================= -->
505<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]506 <a name="callingconv">Calling Conventions</a>
507</div>
508
509<div class="doc_text">
510
511<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
512and <a href="#i_invoke">invokes</a> can all have an optional calling convention
513specified for the call. The calling convention of any pair of dynamic
514caller/callee must match, or the behavior of the program is undefined. The
515following calling conventions are supported by LLVM, and more may be added in
516the future:</p>
517
518<dl>
519 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
520
521 <dd>This calling convention (the default if no other calling convention is
522 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]523 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencer72ba4992006-12-31 21:30:18 +0000[diff] [blame]524 prototype and implemented declaration of the function (as does normal C).
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]525 </dd>
526
527 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
528
529 <dd>This calling convention attempts to make calls as fast as possible
530 (e.g. by passing things in registers). This calling convention allows the
531 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]532 without having to conform to an externally specified ABI. Implementations of
533 this convention should allow arbitrary tail call optimization to be supported.
534 This calling convention does not support varargs and requires the prototype of
535 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]536 </dd>
537
538 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
539
540 <dd>This calling convention attempts to make code in the caller as efficient
541 as possible under the assumption that the call is not commonly executed. As
542 such, these calls often preserve all registers so that the call does not break
543 any live ranges in the caller side. This calling convention does not support
544 varargs and requires the prototype of all callees to exactly match the
545 prototype of the function definition.
546 </dd>
547
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]548 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]549
550 <dd>Any calling convention may be specified by number, allowing
551 target-specific calling conventions to be used. Target specific calling
552 conventions start at 64.
553 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]554</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]555
556<p>More calling conventions can be added/defined on an as-needed basis, to
557support pascal conventions or any other well-known target-independent
558convention.</p>
559
560</div>
561
562<!-- ======================================================================= -->
563<div class="doc_subsection">
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]564 <a name="visibility">Visibility Styles</a>
565</div>
566
567<div class="doc_text">
568
569<p>
570All Global Variables and Functions have one of the following visibility styles:
571</p>
572
573<dl>
574 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
575
576 <dd>On ELF, default visibility means that the declaration is visible to other
577 modules and, in shared libraries, means that the declared entity may be
578 overridden. On Darwin, default visibility means that the declaration is
579 visible to other modules. Default visibility corresponds to "external
580 linkage" in the language.
581 </dd>
582
583 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
584
585 <dd>Two declarations of an object with hidden visibility refer to the same
586 object if they are in the same shared object. Usually, hidden visibility
587 indicates that the symbol will not be placed into the dynamic symbol table,
588 so no other module (executable or shared library) can reference it
589 directly.
590 </dd>
591
592</dl>
593
594</div>
595
596<!-- ======================================================================= -->
597<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]598 <a name="globalvars">Global Variables</a>
599</div>
600
601<div class="doc_text">
602
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]603<p>Global variables define regions of memory allocated at compilation time
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]604instead of run-time. Global variables may optionally be initialized, may have
605an explicit section to be placed in, and may
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]606have an optional explicit alignment specified. A
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]607variable may be defined as a global "constant," which indicates that the
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]608contents of the variable will <b>never</b> be modified (enabling better
609optimization, allowing the global data to be placed in the read-only section of
610an executable, etc). Note that variables that need runtime initialization
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]611cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]612
613<p>
614LLVM explicitly allows <em>declarations</em> of global variables to be marked
615constant, even if the final definition of the global is not. This capability
616can be used to enable slightly better optimization of the program, but requires
617the language definition to guarantee that optimizations based on the
618'constantness' are valid for the translation units that do not include the
619definition.
620</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]621
622<p>As SSA values, global variables define pointer values that are in
623scope (i.e. they dominate) all basic blocks in the program. Global
624variables always define a pointer to their "content" type because they
625describe a region of memory, and all memory objects in LLVM are
626accessed through pointers.</p>
627
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]628<p>LLVM allows an explicit section to be specified for globals. If the target
629supports it, it will emit globals to the section specified.</p>
630
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]631<p>An explicit alignment may be specified for a global. If not present, or if
632the alignment is set to zero, the alignment of the global is set by the target
633to whatever it feels convenient. If an explicit alignment is specified, the
634global is forced to have at least that much alignment. All alignments must be
635a power of 2.</p>
636
Chris Lattner5760c502007-01-14 00:27:09 +0000[diff] [blame]637<p>For example, the following defines a global with an initializer, section,
638 and alignment:</p>
639
640<pre>
641 %G = constant float 1.0, section "foo", align 4
642</pre>
643
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]644</div>
645
646
647<!-- ======================================================================= -->
648<div class="doc_subsection">
649 <a name="functionstructure">Functions</a>
650</div>
651
652<div class="doc_text">
653
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]654<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
655an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]656<a href="#visibility">visibility style</a>, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]657<a href="#callingconv">calling convention</a>, a return type, an optional
658<a href="#paramattrs">parameter attribute</a> for the return type, a function
659name, a (possibly empty) argument list (each with optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame]660<a href="#paramattrs">parameter attributes</a>), an optional section, an
661optional alignment, an opening curly brace, a list of basic blocks, and a
662closing curly brace.
663
664LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
665optional <a href="#linkage">linkage type</a>, an optional
666<a href="#visibility">visibility style</a>, an optional
667<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]668<a href="#paramattrs">parameter attribute</a> for the return type, a function
669name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]670
671<p>A function definition contains a list of basic blocks, forming the CFG for
672the function. Each basic block may optionally start with a label (giving the
673basic block a symbol table entry), contains a list of instructions, and ends
674with a <a href="#terminators">terminator</a> instruction (such as a branch or
675function return).</p>
676
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]677<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]678executed on entrance to the function, and it is not allowed to have predecessor
679basic blocks (i.e. there can not be any branches to the entry block of a
680function). Because the block can have no predecessors, it also cannot have any
681<a href="#i_phi">PHI nodes</a>.</p>
682
683<p>LLVM functions are identified by their name and type signature. Hence, two
684functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]685considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]686appropriately.</p>
687
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]688<p>LLVM allows an explicit section to be specified for functions. If the target
689supports it, it will emit functions to the section specified.</p>
690
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]691<p>An explicit alignment may be specified for a function. If not present, or if
692the alignment is set to zero, the alignment of the function is set by the target
693to whatever it feels convenient. If an explicit alignment is specified, the
694function is forced to have at least that much alignment. All alignments must be
695a power of 2.</p>
696
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]697</div>
698
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]699<!-- ======================================================================= -->
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]700<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
701<div class="doc_text">
702 <p>The return type and each parameter of a function type may have a set of
703 <i>parameter attributes</i> associated with them. Parameter attributes are
704 used to communicate additional information about the result or parameters of
705 a function. Parameter attributes are considered to be part of the function
706 type so two functions types that differ only by the parameter attributes
707 are different function types.</p>
708
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]709 <p>Parameter attributes are simple keywords that follow the type specified. If
710 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]711 example:</p><pre>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]712 %someFunc = i16 (i8 sext %someParam) zext
713 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]714 <p>Note that the two function types above are unique because the parameter has
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]715 a different attribute (sext in the first one, zext in the second). Also note
716 that the attribute for the function result (zext) comes immediately after the
717 argument list.</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]718
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]719 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]720 <dl>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]721 <dt><tt>zext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]722 <dd>This indicates that the parameter should be zero extended just before
723 a call to this function.</dd>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]724 <dt><tt>sext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]725 <dd>This indicates that the parameter should be sign extended just before
726 a call to this function.</dd>
Anton Korobeynikove8166852007-01-28 14:30:45 +0000[diff] [blame]727 <dt><tt>inreg</tt></dt>
728 <dd>This indicates that the parameter should be placed in register (if
Anton Korobeynikove93c6e82007-01-28 15:27:21 +0000[diff] [blame]729 possible) during assembling function call. Support for this attribute is
730 target-specific</dd>
Anton Korobeynikove8166852007-01-28 14:30:45 +0000[diff] [blame]731 <dt><tt>sret</tt></dt>
Anton Korobeynikove93c6e82007-01-28 15:27:21 +0000[diff] [blame]732 <dd>This indicates that the parameter specifies the address of a structure
Reid Spencer05dbb9d2007-03-22 02:02:11 +0000[diff] [blame]733 that is the return value of the function in the source program.</dd>
Reid Spencer9d1700e2007-03-22 02:18:56 +0000[diff] [blame]734 <dt><tt>noreturn</tt></dt>
735 <dd>This function attribute indicates that the function never returns. This
736 indicates to LLVM that every call to this function should be treated as if
737 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
Reid Spencer05dbb9d2007-03-22 02:02:11 +0000[diff] [blame]738 <dt><tt>nounwind</tt></dt>
739 <dd>This function attribute indicates that the function type does not use
740 the unwind instruction and does not allow stack unwinding to propagate
741 through it.</dd>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]742 </dl>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]743
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]744</div>
745
746<!-- ======================================================================= -->
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]747<div class="doc_subsection">
Chris Lattner93564892006-04-08 04:40:53 +0000[diff] [blame]748 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]749</div>
750
751<div class="doc_text">
752<p>
753Modules may contain "module-level inline asm" blocks, which corresponds to the
754GCC "file scope inline asm" blocks. These blocks are internally concatenated by
755LLVM and treated as a single unit, but may be separated in the .ll file if
756desired. The syntax is very simple:
757</p>
758
759<div class="doc_code"><pre>
Chris Lattnera1280ad2006-01-24 00:37:20 +0000[diff] [blame]760 module asm "inline asm code goes here"
761 module asm "more can go here"
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]762</pre></div>
763
764<p>The strings can contain any character by escaping non-printable characters.
765 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
766 for the number.
767</p>
768
769<p>
770 The inline asm code is simply printed to the machine code .s file when
771 assembly code is generated.
772</p>
773</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]774
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]775<!-- ======================================================================= -->
776<div class="doc_subsection">
777 <a name="datalayout">Data Layout</a>
778</div>
779
780<div class="doc_text">
781<p>A module may specify a target specific data layout string that specifies how
782data is to be laid out in memory. The syntax for the data layout is simply:<br/>
783<pre> target datalayout = "<i>layout specification</i>"
784</pre>
785The <i>layout specification</i> consists of a list of specifications separated
786by the minus sign character ('-'). Each specification starts with a letter
787and may include other information after the letter to define some aspect of the
788data layout. The specifications accepted are as follows: </p>
789<dl>
790 <dt><tt>E</tt></dt>
791 <dd>Specifies that the target lays out data in big-endian form. That is, the
792 bits with the most significance have the lowest address location.</dd>
793 <dt><tt>e</tt></dt>
794 <dd>Specifies that hte target lays out data in little-endian form. That is,
795 the bits with the least significance have the lowest address location.</dd>
796 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
797 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
798 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
799 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
800 too.</dd>
801 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
802 <dd>This specifies the alignment for an integer type of a given bit
803 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
804 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
805 <dd>This specifies the alignment for a vector type of a given bit
806 <i>size</i>.</dd>
807 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
808 <dd>This specifies the alignment for a floating point type of a given bit
809 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
810 (double).</dd>
811 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
812 <dd>This specifies the alignment for an aggregate type of a given bit
813 <i>size</i>.</dd>
814</dl>
815<p>When constructing the data layout for a given target, LLVM starts with a
816default set of specifications which are then (possibly) overriden by the
817specifications in the <tt>datalayout</tt> keyword. The default specifications
818are given in this list:</p>
819<ul>
820 <li><tt>E</tt> - big endian</li>
821 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
822 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
823 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
824 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
825 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
826 <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
827 alignment of 64-bits</li>
828 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
829 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
830 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
831 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
832 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
833</ul>
834<p>When llvm is determining the alignment for a given type, it uses the
835following rules:
836<ol>
837 <li>If the type sought is an exact match for one of the specifications, that
838 specification is used.</li>
839 <li>If no match is found, and the type sought is an integer type, then the
840 smallest integer type that is larger than the bitwidth of the sought type is
841 used. If none of the specifications are larger than the bitwidth then the the
842 largest integer type is used. For example, given the default specifications
843 above, the i7 type will use the alignment of i8 (next largest) while both
844 i65 and i256 will use the alignment of i64 (largest specified).</li>
845 <li>If no match is found, and the type sought is a vector type, then the
846 largest vector type that is smaller than the sought vector type will be used
847 as a fall back. This happens because <128 x double> can be implemented in
848 terms of 64 <2 x double>, for example.</li>
849</ol>
850</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]851
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]852<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]853<div class="doc_section"> <a name="typesystem">Type System</a> </div>
854<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]855
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]856<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]857
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]858<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]859intermediate representation. Being typed enables a number of
860optimizations to be performed on the IR directly, without having to do
861extra analyses on the side before the transformation. A strong type
862system makes it easier to read the generated code and enables novel
863analyses and transformations that are not feasible to perform on normal
864three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]865
866</div>
867
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]868<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]869<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]870<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]871<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]872system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]873
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]874<table class="layout">
875 <tr class="layout">
876 <td class="left">
877 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]878 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]879 <tr><th>Type</th><th>Description</th></tr>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]880 <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]881 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
882 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]883 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]884 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]885 </tbody>
886 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]887 </td>
888 <td class="right">
889 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]890 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]891 <tr><th>Type</th><th>Description</th></tr>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]892 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]893 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
894 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]895 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]896 </tbody>
897 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]898 </td>
899 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]900</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]901</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]902
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]903<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]904<div class="doc_subsubsection"> <a name="t_classifications">Type
905Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]906<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]907<p>These different primitive types fall into a few useful
908classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]909
910<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]911 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]912 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]913 <tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]914 <td><a name="t_integer">integer</a></td>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]915 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]916 </tr>
917 <tr>
918 <td><a name="t_floating">floating point</a></td>
919 <td><tt>float, double</tt></td>
920 </tr>
921 <tr>
922 <td><a name="t_firstclass">first class</a></td>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]923 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]924 <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]925 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]926 </tr>
927 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]928</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]929
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]930<p>The <a href="#t_firstclass">first class</a> types are perhaps the
931most important. Values of these types are the only ones which can be
932produced by instructions, passed as arguments, or used as operands to
933instructions. This means that all structures and arrays must be
934manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]935</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]936
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]937<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]938<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]939
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]940<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]941
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]942<p>The real power in LLVM comes from the derived types in the system.
943This is what allows a programmer to represent arrays, functions,
944pointers, and other useful types. Note that these derived types may be
945recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]946
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]947</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]948
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]949<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]950<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]951
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]952<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]953
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]954<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]955
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]956<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]957sequentially in memory. The array type requires a size (number of
958elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]959
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]960<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]961
962<pre>
963 [&lt;# elements&gt; x &lt;elementtype&gt;]
964</pre>
965
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]966<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]967be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]968
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]969<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]970<table class="layout">
971 <tr class="layout">
972 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]973 <tt>[40 x i32 ]</tt><br/>
974 <tt>[41 x i32 ]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]975 <tt>[40 x i8]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]976 </td>
977 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]978 Array of 40 32-bit integer values.<br/>
979 Array of 41 32-bit integer values.<br/>
980 Array of 40 8-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]981 </td>
982 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]983</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]984<p>Here are some examples of multidimensional arrays:</p>
985<table class="layout">
986 <tr class="layout">
987 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]988 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]989 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]990 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]991 </td>
992 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]993 3x4 array of 32-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]994 12x10 array of single precision floating point values.<br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]995 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]996 </td>
997 </tr>
998</table>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]999
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1000<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1001length array. Normally, accesses past the end of an array are undefined in
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1002LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1003As a special case, however, zero length arrays are recognized to be variable
1004length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1005type "{ i32, [0 x float]}", for example.</p>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]1006
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1007</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1008
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1009<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1010<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1011<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1012<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1013<p>The function type can be thought of as a function signature. It
1014consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]1015Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1016(which are structures of pointers to functions), for indirect function
1017calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]1018<p>
1019The return type of a function type cannot be an aggregate type.
1020</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1021<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1022<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1023<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]1024specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1025which indicates that the function takes a variable number of arguments.
1026Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1027 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1028<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1029<table class="layout">
1030 <tr class="layout">
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1031 <td class="left"><tt>i32 (i32)</tt></td>
1032 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1033 </td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1034 </tr><tr class="layout">
Reid Spencere6a338d2007-01-15 18:28:34 +0000[diff] [blame]1035 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencer655dcc62006-12-31 07:20:23 +0000[diff] [blame]1036 </tt></td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1037 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1038 an <tt>i16</tt> that should be sign extended and a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1039 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1040 <tt>float</tt>.
1041 </td>
1042 </tr><tr class="layout">
1043 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1044 <td class="left">A vararg function that takes at least one
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1045 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]1046 which returns an integer. This is the signature for <tt>printf</tt> in
1047 LLVM.
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1048 </td>
1049 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1050</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1051
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1052</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1053<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1054<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1055<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1056<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1057<p>The structure type is used to represent a collection of data members
1058together in memory. The packing of the field types is defined to match
1059the ABI of the underlying processor. The elements of a structure may
1060be any type that has a size.</p>
1061<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1062and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1063field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1064instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1065<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1066<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1067<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1068<table class="layout">
1069 <tr class="layout">
1070 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1071 <tt>{ i32, i32, i32 }</tt><br/>
1072 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1073 </td>
1074 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1075 a triple of three <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1076 A pair, where the first element is a <tt>float</tt> and the second element
1077 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]1078 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1079 </td>
1080 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1081</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1082</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1083
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1084<!-- _______________________________________________________________________ -->
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1085<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1086</div>
1087<div class="doc_text">
1088<h5>Overview:</h5>
1089<p>The packed structure type is used to represent a collection of data members
1090together in memory. There is no padding between fields. Further, the alignment
1091of a packed structure is 1 byte. The elements of a packed structure may
1092be any type that has a size.</p>
1093<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1094and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1095field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1096instruction.</p>
1097<h5>Syntax:</h5>
1098<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1099<h5>Examples:</h5>
1100<table class="layout">
1101 <tr class="layout">
1102 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1103 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1104 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1105 </td>
1106 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1107 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1108 A pair, where the first element is a <tt>float</tt> and the second element
1109 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]1110 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1111 </td>
1112 </tr>
1113</table>
1114</div>
1115
1116<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1117<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1118<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1119<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1120<p>As in many languages, the pointer type represents a pointer or
1121reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1122<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1123<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1124<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1125<table class="layout">
1126 <tr class="layout">
1127 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1128 <tt>[4x i32]*</tt><br/>
1129 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1130 </td>
1131 <td class="left">
1132 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]1133 four <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1134 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1135 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1136 <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1137 </td>
1138 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1139</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1140</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1141
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1142<!-- _______________________________________________________________________ -->
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1143<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1144<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1145
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1146<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1147
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1148<p>A vector type is a simple derived type that represents a vector
1149of elements. Vector types are used when multiple primitive data
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1150are operated in parallel using a single instruction (SIMD).
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1151A vector type requires a size (number of
Chris Lattner330ce692005-11-10 01:44:22 +0000[diff] [blame]1152elements) and an underlying primitive data type. Vectors must have a power
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1153of two length (1, 2, 4, 8, 16 ...). Vector types are
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1154considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1155
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1156<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1157
1158<pre>
1159 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1160</pre>
1161
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1162<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1163be any integer or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1164
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1165<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1166
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1167<table class="layout">
1168 <tr class="layout">
1169 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1170 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1171 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1172 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1173 </td>
1174 <td class="left">
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1175 Vector of 4 32-bit integer values.<br/>
1176 Vector of 8 floating-point values.<br/>
1177 Vector of 2 64-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1178 </td>
1179 </tr>
1180</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1181</div>
1182
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1183<!-- _______________________________________________________________________ -->
1184<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1185<div class="doc_text">
1186
1187<h5>Overview:</h5>
1188
1189<p>Opaque types are used to represent unknown types in the system. This
1190corresponds (for example) to the C notion of a foward declared structure type.
1191In LLVM, opaque types can eventually be resolved to any type (not just a
1192structure type).</p>
1193
1194<h5>Syntax:</h5>
1195
1196<pre>
1197 opaque
1198</pre>
1199
1200<h5>Examples:</h5>
1201
1202<table class="layout">
1203 <tr class="layout">
1204 <td class="left">
1205 <tt>opaque</tt>
1206 </td>
1207 <td class="left">
1208 An opaque type.<br/>
1209 </td>
1210 </tr>
1211</table>
1212</div>
1213
1214
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1215<!-- *********************************************************************** -->
1216<div class="doc_section"> <a name="constants">Constants</a> </div>
1217<!-- *********************************************************************** -->
1218
1219<div class="doc_text">
1220
1221<p>LLVM has several different basic types of constants. This section describes
1222them all and their syntax.</p>
1223
1224</div>
1225
1226<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1227<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1228
1229<div class="doc_text">
1230
1231<dl>
1232 <dt><b>Boolean constants</b></dt>
1233
1234 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1235 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1236 </dd>
1237
1238 <dt><b>Integer constants</b></dt>
1239
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1240 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1241 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1242 integer types.
1243 </dd>
1244
1245 <dt><b>Floating point constants</b></dt>
1246
1247 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1248 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1249 notation (see below). Floating point constants must have a <a
1250 href="#t_floating">floating point</a> type. </dd>
1251
1252 <dt><b>Null pointer constants</b></dt>
1253
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1254 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1255 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1256
1257</dl>
1258
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1259<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1260of floating point constants. For example, the form '<tt>double
12610x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
12624.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1263(and the only time that they are generated by the disassembler) is when a
1264floating point constant must be emitted but it cannot be represented as a
1265decimal floating point number. For example, NaN's, infinities, and other
1266special values are represented in their IEEE hexadecimal format so that
1267assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1268
1269</div>
1270
1271<!-- ======================================================================= -->
1272<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1273</div>
1274
1275<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1276<p>Aggregate constants arise from aggregation of simple constants
1277and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1278
1279<dl>
1280 <dt><b>Structure constants</b></dt>
1281
1282 <dd>Structure constants are represented with notation similar to structure
1283 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1284 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1285 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]1286 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1287 types of elements must match those specified by the type.
1288 </dd>
1289
1290 <dt><b>Array constants</b></dt>
1291
1292 <dd>Array constants are represented with notation similar to array type
1293 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1294 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1295 constants must have <a href="#t_array">array type</a>, and the number and
1296 types of elements must match those specified by the type.
1297 </dd>
1298
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1299 <dt><b>Vector constants</b></dt>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1300
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1301 <dd>Vector constants are represented with notation similar to vector type
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1302 definitions (a comma separated list of elements, surrounded by
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1303 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]1304 i32 11, i32 74, i32 100 &gt;</tt>". VEctor constants must have <a
1305 href="#t_vector">vector type</a>, and the number and types of elements must
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1306 match those specified by the type.
1307 </dd>
1308
1309 <dt><b>Zero initialization</b></dt>
1310
1311 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1312 value to zero of <em>any</em> type, including scalar and aggregate types.
1313 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]1314 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1315 initializers.
1316 </dd>
1317</dl>
1318
1319</div>
1320
1321<!-- ======================================================================= -->
1322<div class="doc_subsection">
1323 <a name="globalconstants">Global Variable and Function Addresses</a>
1324</div>
1325
1326<div class="doc_text">
1327
1328<p>The addresses of <a href="#globalvars">global variables</a> and <a
1329href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1330constants. These constants are explicitly referenced when the <a
1331href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1332href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1333file:</p>
1334
1335<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1336 %X = global i32 17
1337 %Y = global i32 42
1338 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1339</pre>
1340
1341</div>
1342
1343<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1344<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1345<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1346 <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]1347 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1348 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1349
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1350 <p>Undefined values indicate to the compiler that the program is well defined
1351 no matter what value is used, giving the compiler more freedom to optimize.
1352 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1353</div>
1354
1355<!-- ======================================================================= -->
1356<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1357</div>
1358
1359<div class="doc_text">
1360
1361<p>Constant expressions are used to allow expressions involving other constants
1362to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1363href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1364that does not have side effects (e.g. load and call are not supported). The
1365following is the syntax for constant expressions:</p>
1366
1367<dl>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1368 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1369 <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]1370 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1371
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1372 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1373 <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]1374 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]1375
1376 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1377 <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]1378 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]1379
1380 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1381 <dd>Truncate a floating point constant to another floating point type. The
1382 size of CST must be larger than the size of TYPE. Both types must be
1383 floating point.</dd>
1384
1385 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1386 <dd>Floating point extend a constant to another type. The size of CST must be
1387 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1388
1389 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1390 <dd>Convert a floating point constant to the corresponding unsigned integer
1391 constant. TYPE must be an integer type. CST must be floating point. If the
1392 value won't fit in the integer type, the results are undefined.</dd>
1393
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1394 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1395 <dd>Convert a floating point constant to the corresponding signed integer
1396 constant. TYPE must be an integer type. CST must be floating point. If the
1397 value won't fit in the integer type, the results are undefined.</dd>
1398
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1399 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1400 <dd>Convert an unsigned integer constant to the corresponding floating point
1401 constant. TYPE must be floating point. CST must be of integer type. If the
1402 value won't fit in the floating point type, the results are undefined.</dd>
1403
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1404 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1405 <dd>Convert a signed integer constant to the corresponding floating point
1406 constant. TYPE must be floating point. CST must be of integer type. If the
1407 value won't fit in the floating point type, the results are undefined.</dd>
1408
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1409 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1410 <dd>Convert a pointer typed constant to the corresponding integer constant
1411 TYPE must be an integer type. CST must be of pointer type. The CST value is
1412 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1413
1414 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1415 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1416 pointer type. CST must be of integer type. The CST value is zero extended,
1417 truncated, or unchanged to make it fit in a pointer size. This one is
1418 <i>really</i> dangerous!</dd>
1419
1420 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1421 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1422 identical (same number of bits). The conversion is done as if the CST value
1423 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]1424 with this operator, just the type. This can be used for conversion of
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1425 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]1426 pointers it is only valid to cast to another pointer type.
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1427 </dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1428
1429 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1430
1431 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1432 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1433 instruction, the index list may have zero or more indexes, which are required
1434 to make sense for the type of "CSTPTR".</dd>
1435
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1436 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1437
1438 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1439 constants.</dd>
1440
1441 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1442 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1443
1444 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1445 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1446
1447 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1448
1449 <dd>Perform the <a href="#i_extractelement">extractelement
1450 operation</a> on constants.
1451
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1452 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1453
1454 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1455 operation</a> on constants.</dd>
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1456
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1457
1458 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1459
1460 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1461 operation</a> on constants.</dd>
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1462
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1463 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1464
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1465 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1466 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1467 binary</a> operations. The constraints on operands are the same as those for
1468 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1469 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1470</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1471</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1472
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1473<!-- *********************************************************************** -->
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1474<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1475<!-- *********************************************************************** -->
1476
1477<!-- ======================================================================= -->
1478<div class="doc_subsection">
1479<a name="inlineasm">Inline Assembler Expressions</a>
1480</div>
1481
1482<div class="doc_text">
1483
1484<p>
1485LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1486Module-Level Inline Assembly</a>) through the use of a special value. This
1487value represents the inline assembler as a string (containing the instructions
1488to emit), a list of operand constraints (stored as a string), and a flag that
1489indicates whether or not the inline asm expression has side effects. An example
1490inline assembler expression is:
1491</p>
1492
1493<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1494 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1495</pre>
1496
1497<p>
1498Inline assembler expressions may <b>only</b> be used as the callee operand of
1499a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1500</p>
1501
1502<pre>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]1503 %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]1504</pre>
1505
1506<p>
1507Inline asms with side effects not visible in the constraint list must be marked
1508as having side effects. This is done through the use of the
1509'<tt>sideeffect</tt>' keyword, like so:
1510</p>
1511
1512<pre>
1513 call void asm sideeffect "eieio", ""()
1514</pre>
1515
1516<p>TODO: The format of the asm and constraints string still need to be
1517documented here. Constraints on what can be done (e.g. duplication, moving, etc
1518need to be documented).
1519</p>
1520
1521</div>
1522
1523<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1524<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1525<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1526
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1527<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1528
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1529<p>The LLVM instruction set consists of several different
1530classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1531instructions</a>, <a href="#binaryops">binary instructions</a>,
1532<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1533 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1534instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1535
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1536</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1537
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1538<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1539<div class="doc_subsection"> <a name="terminators">Terminator
1540Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1541
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1542<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1543
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1544<p>As mentioned <a href="#functionstructure">previously</a>, every
1545basic block in a program ends with a "Terminator" instruction, which
1546indicates which block should be executed after the current block is
1547finished. These terminator instructions typically yield a '<tt>void</tt>'
1548value: they produce control flow, not values (the one exception being
1549the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1550<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1551 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1552instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1553the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1554 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1555 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1556
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1557</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1558
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1559<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1560<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1561Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1562<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1563<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1564<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]1565 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1566</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1567<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1568<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1569value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1570<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1571returns a value and then causes control flow, and one that just causes
1572control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1573<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1574<p>The '<tt>ret</tt>' instruction may return any '<a
1575 href="#t_firstclass">first class</a>' type. Notice that a function is
1576not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1577instruction inside of the function that returns a value that does not
1578match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1579<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1580<p>When the '<tt>ret</tt>' instruction is executed, control flow
1581returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1582 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1583the instruction after the call. If the caller was an "<a
1584 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1585at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1586returns a value, that value shall set the call or invoke instruction's
1587return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1588<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1589<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1590 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1591</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1592</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1593<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1594<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1595<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1596<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1597<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]1598</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1599<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1600<p>The '<tt>br</tt>' instruction is used to cause control flow to
1601transfer to a different basic block in the current function. There are
1602two forms of this instruction, corresponding to a conditional branch
1603and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1604<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1605<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1606single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Reid Spencer50c723a2007-02-19 23:54:10 +0000[diff] [blame]1607unconditional form of the '<tt>br</tt>' instruction takes a single
1608'<tt>label</tt>' value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1609<h5>Semantics:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1610<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1611argument is evaluated. If the value is <tt>true</tt>, control flows
1612to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1613control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1614<h5>Example:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1615<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]1616 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]1617</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1618<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1619<div class="doc_subsubsection">
1620 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1621</div>
1622
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1623<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1624<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1625
1626<pre>
1627 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1628</pre>
1629
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1630<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1631
1632<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1633several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1634instruction, allowing a branch to occur to one of many possible
1635destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1636
1637
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1638<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1639
1640<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1641comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1642an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1643table is not allowed to contain duplicate constant entries.</p>
1644
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1645<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1646
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1647<p>The <tt>switch</tt> instruction specifies a table of values and
1648destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1649table is searched for the given value. If the value is found, control flow is
1650transfered to the corresponding destination; otherwise, control flow is
1651transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1652
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1653<h5>Implementation:</h5>
1654
1655<p>Depending on properties of the target machine and the particular
1656<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1657ways. For example, it could be generated as a series of chained conditional
1658branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1659
1660<h5>Example:</h5>
1661
1662<pre>
1663 <i>; Emulate a conditional br instruction</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1664 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1665 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1666
1667 <i>; Emulate an unconditional br instruction</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1668 switch i32 0, label %dest [ ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1669
1670 <i>; Implement a jump table:</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1671 switch i32 %val, label %otherwise [ i32 0, label %onzero
1672 i32 1, label %onone
1673 i32 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1674</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1675</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1676
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1677<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1678<div class="doc_subsubsection">
1679 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1680</div>
1681
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1682<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1683
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1684<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1685
1686<pre>
1687 &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]1688 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1689</pre>
1690
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1691<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1692
1693<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1694function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1695'<tt>normal</tt>' label or the
1696'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1697"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1698"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1699href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1700continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1701
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1702<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1703
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1704<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1705
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1706<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1707 <li>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]1708 The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1709 convention</a> the call should use. If none is specified, the call defaults
1710 to using C calling conventions.
1711 </li>
1712 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1713 function value being invoked. In most cases, this is a direct function
1714 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1715 an arbitrary pointer to function value.
1716 </li>
1717
1718 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1719 function to be invoked. </li>
1720
1721 <li>'<tt>function args</tt>': argument list whose types match the function
1722 signature argument types. If the function signature indicates the function
1723 accepts a variable number of arguments, the extra arguments can be
1724 specified. </li>
1725
1726 <li>'<tt>normal label</tt>': the label reached when the called function
1727 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1728
1729 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1730 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1731
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1732</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1733
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1734<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1735
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1736<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1737href="#i_call">call</a></tt>' instruction in most regards. The primary
1738difference is that it establishes an association with a label, which is used by
1739the runtime library to unwind the stack.</p>
1740
1741<p>This instruction is used in languages with destructors to ensure that proper
1742cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1743exception. Additionally, this is important for implementation of
1744'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1745
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1746<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1747<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1748 %retval = invoke i32 %Test(i32 15) to label %Continue
1749 unwind label %TestCleanup <i>; {i32}:retval set</i>
1750 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1751 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1752</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1753</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1754
1755
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1756<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1757
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1758<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1759Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1760
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1761<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1762
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1763<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1764<pre>
1765 unwind
1766</pre>
1767
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1768<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1769
1770<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1771at the first callee in the dynamic call stack which used an <a
1772href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1773primarily used to implement exception handling.</p>
1774
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1775<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1776
1777<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1778immediately halt. The dynamic call stack is then searched for the first <a
1779href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1780execution continues at the "exceptional" destination block specified by the
1781<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1782dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1783</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1784
1785<!-- _______________________________________________________________________ -->
1786
1787<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1788Instruction</a> </div>
1789
1790<div class="doc_text">
1791
1792<h5>Syntax:</h5>
1793<pre>
1794 unreachable
1795</pre>
1796
1797<h5>Overview:</h5>
1798
1799<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1800instruction is used to inform the optimizer that a particular portion of the
1801code is not reachable. This can be used to indicate that the code after a
1802no-return function cannot be reached, and other facts.</p>
1803
1804<h5>Semantics:</h5>
1805
1806<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1807</div>
1808
1809
1810
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1811<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1812<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1813<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1814<p>Binary operators are used to do most of the computation in a
1815program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1816produce a single value. The operands might represent
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1817multiple 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]1818The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1819necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1820<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1821</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1822<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1823<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1824Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1825<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1826<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1827<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]1828</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1829<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1830<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1831<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1832<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1833 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1834 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]1835Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1836<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1837<p>The value produced is the integer or floating point sum of the two
1838operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1839<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1840<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]1841</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1842</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1843<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1844<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1845Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1846<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1847<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1848<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]1849</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1850<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1851<p>The '<tt>sub</tt>' instruction returns the difference of its two
1852operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1853<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1854instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1855<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1856<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1857 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1858values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1859This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1860Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1861<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1862<p>The value produced is the integer or floating point difference of
1863the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1864<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1865<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1866 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1867</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1868</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1869<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1870<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1871Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1872<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1873<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1874<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]1875</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1876<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1877<p>The '<tt>mul</tt>' instruction returns the product of its two
1878operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1879<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1880<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1881 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1882values.
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1883This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1884Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1885<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1886<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1887two operands.</p>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1888<p>Because the operands are the same width, the result of an integer
1889multiplication is the same whether the operands should be deemed unsigned or
1890signed.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1891<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1892<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]1893</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1894</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1895<!-- _______________________________________________________________________ -->
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1896<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1897</a></div>
1898<div class="doc_text">
1899<h5>Syntax:</h5>
1900<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1901</pre>
1902<h5>Overview:</h5>
1903<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1904operands.</p>
1905<h5>Arguments:</h5>
1906<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1907<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1908types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1909of the values in which case the elements must be integers.</p>
1910<h5>Semantics:</h5>
1911<p>The value produced is the unsigned integer quotient of the two operands. This
1912instruction always performs an unsigned division operation, regardless of
1913whether the arguments are unsigned or not.</p>
1914<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1915<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]1916</pre>
1917</div>
1918<!-- _______________________________________________________________________ -->
1919<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1920</a> </div>
1921<div class="doc_text">
1922<h5>Syntax:</h5>
1923<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1924</pre>
1925<h5>Overview:</h5>
1926<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1927operands.</p>
1928<h5>Arguments:</h5>
1929<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1930<a href="#t_integer">integer</a> values. Both arguments must have identical
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1931types. This instruction can also take <a href="#t_vector">vector</a> versions
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1932of the values in which case the elements must be integers.</p>
1933<h5>Semantics:</h5>
1934<p>The value produced is the signed integer quotient of the two operands. This
1935instruction always performs a signed division operation, regardless of whether
1936the arguments are signed or not.</p>
1937<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1938<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]1939</pre>
1940</div>
1941<!-- _______________________________________________________________________ -->
1942<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1943Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1944<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1945<h5>Syntax:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1946<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]1947</pre>
1948<h5>Overview:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1949<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1950operands.</p>
1951<h5>Arguments:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1952<p>The two arguments to the '<tt>div</tt>' instruction must be
1953<a href="#t_floating">floating point</a> values. Both arguments must have
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]1954identical types. This instruction can also take <a href="#t_vector">vector</a>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1955versions of the values in which case the elements must be floating point.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1956<h5>Semantics:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1957<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1958<h5>Example:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1959<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]1960</pre>
1961</div>
1962<!-- _______________________________________________________________________ -->
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1963<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1964</div>
1965<div class="doc_text">
1966<h5>Syntax:</h5>
1967<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1968</pre>
1969<h5>Overview:</h5>
1970<p>The '<tt>urem</tt>' instruction returns the remainder from the
1971unsigned division of its two arguments.</p>
1972<h5>Arguments:</h5>
1973<p>The two arguments to the '<tt>urem</tt>' instruction must be
1974<a href="#t_integer">integer</a> values. Both arguments must have identical
1975types.</p>
1976<h5>Semantics:</h5>
1977<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1978This instruction always performs an unsigned division to get the remainder,
1979regardless of whether the arguments are unsigned or not.</p>
1980<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1981<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]1982</pre>
1983
1984</div>
1985<!-- _______________________________________________________________________ -->
1986<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1987Instruction</a> </div>
1988<div class="doc_text">
1989<h5>Syntax:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1990<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]1991</pre>
1992<h5>Overview:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1993<p>The '<tt>srem</tt>' instruction returns the remainder from the
1994signed division of its two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1995<h5>Arguments:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1996<p>The two arguments to the '<tt>srem</tt>' instruction must be
1997<a href="#t_integer">integer</a> values. Both arguments must have identical
1998types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1999<h5>Semantics:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]2000<p>This instruction returns the <i>remainder</i> of a division (where the result
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2001has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i>
2002operator (where the result has the same sign as the divisor, <tt>var2</tt>) of
2003a value. For more information about the difference, see <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2004 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2005Math Forum</a>. For a table of how this is implemented in various languages,
Reid Spencerdb3b93b2007-03-24 22:40:44 +0000[diff] [blame]2006please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
Reid Spencer806ad6a2007-03-24 22:23:39 +0000[diff] [blame]2007Wikipedia: modulo operation</a>.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2008<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2009<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]2010</pre>
2011
2012</div>
2013<!-- _______________________________________________________________________ -->
2014<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
2015Instruction</a> </div>
2016<div class="doc_text">
2017<h5>Syntax:</h5>
2018<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2019</pre>
2020<h5>Overview:</h5>
2021<p>The '<tt>frem</tt>' instruction returns the remainder from the
2022division of its two operands.</p>
2023<h5>Arguments:</h5>
2024<p>The two arguments to the '<tt>frem</tt>' instruction must be
2025<a href="#t_floating">floating point</a> values. Both arguments must have
2026identical types.</p>
2027<h5>Semantics:</h5>
2028<p>This instruction returns the <i>remainder</i> of a division.</p>
2029<h5>Example:</h5>
2030<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]2031</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2032</div>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]2033
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]2034<!-- ======================================================================= -->
2035<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2036Operations</a> </div>
2037<div class="doc_text">
2038<p>Bitwise binary operators are used to do various forms of
2039bit-twiddling in a program. They are generally very efficient
2040instructions and can commonly be strength reduced from other
2041instructions. They require two operands, execute an operation on them,
2042and produce a single value. The resulting value of the bitwise binary
2043operators is always the same type as its first operand.</p>
2044</div>
2045
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2046<!-- _______________________________________________________________________ -->
2047<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2048Instruction</a> </div>
2049<div class="doc_text">
2050<h5>Syntax:</h5>
2051<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2052</pre>
2053<h5>Overview:</h5>
2054<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2055the left a specified number of bits.</p>
2056<h5>Arguments:</h5>
2057<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2058 href="#t_integer">integer</a> type.</p>
2059<h5>Semantics:</h5>
2060<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
2061<h5>Example:</h5><pre>
2062 &lt;result&gt; = shl i32 4, %var <i>; yields {i32}: 4 &lt;&lt; %var</i>
2063 &lt;result&gt; = shl i32 4, 2 <i>; yields {i32}: 16</i>
2064 &lt;result&gt; = shl i32 1, 10 <i>; yields {i32}: 1024</i>
2065</pre>
2066</div>
2067<!-- _______________________________________________________________________ -->
2068<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2069Instruction</a> </div>
2070<div class="doc_text">
2071<h5>Syntax:</h5>
2072<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2073</pre>
2074
2075<h5>Overview:</h5>
2076<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2077operand shifted to the right a specified number of bits.</p>
2078
2079<h5>Arguments:</h5>
2080<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2081<a href="#t_integer">integer</a> type.</p>
2082
2083<h5>Semantics:</h5>
2084<p>This instruction always performs a logical shift right operation. The most
2085significant bits of the result will be filled with zero bits after the
2086shift.</p>
2087
2088<h5>Example:</h5>
2089<pre>
2090 &lt;result&gt; = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2091 &lt;result&gt; = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2092 &lt;result&gt; = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2093 &lt;result&gt; = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2094</pre>
2095</div>
2096
Reid Spencer2ab01932007-02-02 13:57:07 +0000[diff] [blame]2097<!-- _______________________________________________________________________ -->
Reid Spencer04e259b2007-01-31 21:39:12 +0000[diff] [blame]2098<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2099Instruction</a> </div>
2100<div class="doc_text">
2101
2102<h5>Syntax:</h5>
2103<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
2104</pre>
2105
2106<h5>Overview:</h5>
2107<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2108operand shifted to the right a specified number of bits.</p>
2109
2110<h5>Arguments:</h5>
2111<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2112<a href="#t_integer">integer</a> type.</p>
2113
2114<h5>Semantics:</h5>
2115<p>This instruction always performs an arithmetic shift right operation,
2116The most significant bits of the result will be filled with the sign bit
2117of <tt>var1</tt>.</p>
2118
2119<h5>Example:</h5>
2120<pre>
2121 &lt;result&gt; = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2122 &lt;result&gt; = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2123 &lt;result&gt; = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2124 &lt;result&gt; = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
2125</pre>
2126</div>
2127
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2128<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2129<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2130Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2131<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2132<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2133<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]2134</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2135<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2136<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2137its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2138<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2139<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2140 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2141identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2142<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2143<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2144<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2145<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2146<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2147 <tbody>
2148 <tr>
2149 <td>In0</td>
2150 <td>In1</td>
2151 <td>Out</td>
2152 </tr>
2153 <tr>
2154 <td>0</td>
2155 <td>0</td>
2156 <td>0</td>
2157 </tr>
2158 <tr>
2159 <td>0</td>
2160 <td>1</td>
2161 <td>0</td>
2162 </tr>
2163 <tr>
2164 <td>1</td>
2165 <td>0</td>
2166 <td>0</td>
2167 </tr>
2168 <tr>
2169 <td>1</td>
2170 <td>1</td>
2171 <td>1</td>
2172 </tr>
2173 </tbody>
2174</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2175</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2176<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2177<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2178 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2179 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2180</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2181</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2182<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2183<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2184<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2185<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2186<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]2187</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2188<h5>Overview:</h5>
2189<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2190or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2191<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2192<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2193 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2194identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2195<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2196<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2197<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2198<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2199<table border="1" cellspacing="0" cellpadding="4">
2200 <tbody>
2201 <tr>
2202 <td>In0</td>
2203 <td>In1</td>
2204 <td>Out</td>
2205 </tr>
2206 <tr>
2207 <td>0</td>
2208 <td>0</td>
2209 <td>0</td>
2210 </tr>
2211 <tr>
2212 <td>0</td>
2213 <td>1</td>
2214 <td>1</td>
2215 </tr>
2216 <tr>
2217 <td>1</td>
2218 <td>0</td>
2219 <td>1</td>
2220 </tr>
2221 <tr>
2222 <td>1</td>
2223 <td>1</td>
2224 <td>1</td>
2225 </tr>
2226 </tbody>
2227</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2228</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2229<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2230<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2231 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2232 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2233</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2234</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2235<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2236<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2237Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2238<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2239<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2240<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]2241</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2242<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2243<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2244or of its two operands. The <tt>xor</tt> is used to implement the
2245"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2246<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2247<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2248 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2249identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2250<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2251<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2252<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2253<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2254<table border="1" cellspacing="0" cellpadding="4">
2255 <tbody>
2256 <tr>
2257 <td>In0</td>
2258 <td>In1</td>
2259 <td>Out</td>
2260 </tr>
2261 <tr>
2262 <td>0</td>
2263 <td>0</td>
2264 <td>0</td>
2265 </tr>
2266 <tr>
2267 <td>0</td>
2268 <td>1</td>
2269 <td>1</td>
2270 </tr>
2271 <tr>
2272 <td>1</td>
2273 <td>0</td>
2274 <td>1</td>
2275 </tr>
2276 <tr>
2277 <td>1</td>
2278 <td>1</td>
2279 <td>0</td>
2280 </tr>
2281 </tbody>
2282</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2283</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2284<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2285<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2286<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2287 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2288 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2289 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2290</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2291</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2292
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2293<!-- ======================================================================= -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2294<div class="doc_subsection">
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2295 <a name="vectorops">Vector Operations</a>
2296</div>
2297
2298<div class="doc_text">
2299
2300<p>LLVM supports several instructions to represent vector operations in a
2301target-independent manner. This instructions cover the element-access and
2302vector-specific operations needed to process vectors effectively. While LLVM
2303does directly support these vector operations, many sophisticated algorithms
2304will want to use target-specific intrinsics to take full advantage of a specific
2305target.</p>
2306
2307</div>
2308
2309<!-- _______________________________________________________________________ -->
2310<div class="doc_subsubsection">
2311 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2312</div>
2313
2314<div class="doc_text">
2315
2316<h5>Syntax:</h5>
2317
2318<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2319 &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]2320</pre>
2321
2322<h5>Overview:</h5>
2323
2324<p>
2325The '<tt>extractelement</tt>' instruction extracts a single scalar
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2326element from a vector at a specified index.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2327</p>
2328
2329
2330<h5>Arguments:</h5>
2331
2332<p>
2333The first operand of an '<tt>extractelement</tt>' instruction is a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2334value of <a href="#t_vector">vector</a> type. The second operand is
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2335an index indicating the position from which to extract the element.
2336The index may be a variable.</p>
2337
2338<h5>Semantics:</h5>
2339
2340<p>
2341The result is a scalar of the same type as the element type of
2342<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2343<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2344results are undefined.
2345</p>
2346
2347<h5>Example:</h5>
2348
2349<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2350 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2351</pre>
2352</div>
2353
2354
2355<!-- _______________________________________________________________________ -->
2356<div class="doc_subsubsection">
2357 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2358</div>
2359
2360<div class="doc_text">
2361
2362<h5>Syntax:</h5>
2363
2364<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2365 &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]2366</pre>
2367
2368<h5>Overview:</h5>
2369
2370<p>
2371The '<tt>insertelement</tt>' instruction inserts a scalar
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2372element into a vector at a specified index.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2373</p>
2374
2375
2376<h5>Arguments:</h5>
2377
2378<p>
2379The first operand of an '<tt>insertelement</tt>' instruction is a
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2380value of <a href="#t_vector">vector</a> type. The second operand is a
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2381scalar value whose type must equal the element type of the first
2382operand. The third operand is an index indicating the position at
2383which to insert the value. The index may be a variable.</p>
2384
2385<h5>Semantics:</h5>
2386
2387<p>
Reid Spencer404a3252007-02-15 03:07:05 +0000[diff] [blame]2388The result is a vector of the same type as <tt>val</tt>. Its
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2389element values are those of <tt>val</tt> except at position
2390<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2391exceeds the length of <tt>val</tt>, the results are undefined.
2392</p>
2393
2394<h5>Example:</h5>
2395
2396<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2397 %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]2398</pre>
2399</div>
2400
2401<!-- _______________________________________________________________________ -->
2402<div class="doc_subsubsection">
2403 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2404</div>
2405
2406<div class="doc_text">
2407
2408<h5>Syntax:</h5>
2409
2410<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2411 &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]2412</pre>
2413
2414<h5>Overview:</h5>
2415
2416<p>
2417The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2418from two input vectors, returning a vector of the same type.
2419</p>
2420
2421<h5>Arguments:</h5>
2422
2423<p>
2424The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2425with types that match each other and types that match the result of the
2426instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2427of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2428</p>
2429
2430<p>
2431The shuffle mask operand is required to be a constant vector with either
2432constant integer or undef values.
2433</p>
2434
2435<h5>Semantics:</h5>
2436
2437<p>
2438The elements of the two input vectors are numbered from left to right across
2439both of the vectors. The shuffle mask operand specifies, for each element of
2440the result vector, which element of the two input registers the result element
2441gets. The element selector may be undef (meaning "don't care") and the second
2442operand may be undef if performing a shuffle from only one vector.
2443</p>
2444
2445<h5>Example:</h5>
2446
2447<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2448 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2449 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2450 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2451 &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]2452</pre>
2453</div>
2454
Tanya Lattnerb138bbe2006-04-14 19:24:33 +0000[diff] [blame]2455
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2456<!-- ======================================================================= -->
2457<div class="doc_subsection">
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2458 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2459</div>
2460
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2461<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2462
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2463<p>A key design point of an SSA-based representation is how it
2464represents memory. In LLVM, no memory locations are in SSA form, which
2465makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2466allocate, and free memory in LLVM.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2467
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2468</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2469
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2470<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2471<div class="doc_subsubsection">
2472 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2473</div>
2474
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2475<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2476
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2477<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2478
2479<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2480 &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]2481</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2482
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2483<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2484
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2485<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2486heap and returns a pointer to it.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2487
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2488<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2489
2490<p>The '<tt>malloc</tt>' instruction allocates
2491<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]2492bytes of memory from the operating system and returns a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2493appropriate type to the program. If "NumElements" is specified, it is the
2494number of elements allocated. If an alignment is specified, the value result
2495of the allocation is guaranteed to be aligned to at least that boundary. If
2496not specified, or if zero, the target can choose to align the allocation on any
2497convenient boundary.</p>
2498
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2499<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2500
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2501<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2502
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2503<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2504a pointer is returned.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2505
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2506<h5>Example:</h5>
2507
2508<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2509 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2510
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2511 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2512 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2513 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2514 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2515 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2516</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2517</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2518
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2519<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2520<div class="doc_subsubsection">
2521 <a name="i_free">'<tt>free</tt>' Instruction</a>
2522</div>
2523
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2524<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2525
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2526<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2527
2528<pre>
2529 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2530</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2531
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2532<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2533
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2534<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2535memory heap to be reallocated in the future.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2536
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2537<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2538
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2539<p>'<tt>value</tt>' shall be a pointer value that points to a value
2540that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2541instruction.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2542
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2543<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2544
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2545<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2546after this instruction executes.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2547
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2548<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2549
2550<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2551 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2552 free [4 x i8]* %array
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2553</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2554</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2555
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2556<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2557<div class="doc_subsubsection">
2558 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2559</div>
2560
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2561<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2562
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2563<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2564
2565<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2566 &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]2567</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2568
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2569<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2570
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2571<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2572stack frame of the procedure that is live until the current function
2573returns to its caller.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2574
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2575<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2576
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2577<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2578bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2579appropriate type to the program. If "NumElements" is specified, it is the
2580number of elements allocated. If an alignment is specified, the value result
2581of the allocation is guaranteed to be aligned to at least that boundary. If
2582not specified, or if zero, the target can choose to align the allocation on any
2583convenient boundary.</p>
2584
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2585<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2586
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2587<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2588
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2589<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2590memory is automatically released when the function returns. The '<tt>alloca</tt>'
2591instruction is commonly used to represent automatic variables that must
2592have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]2593 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]2594instructions), the memory is reclaimed.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2595
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2596<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2597
2598<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2599 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2600 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2601 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2602 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2603</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2604</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2605
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2606<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2607<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2608Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2609<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2610<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2611<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]2612<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2613<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2614<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2615<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2616address from which to load. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2617 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2618marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2619the number or order of execution of this <tt>load</tt> with other
2620volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2621instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2622<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2623<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2624<h5>Examples:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2625<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2626 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2627 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2628 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2629</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2630</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2631<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2632<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2633Instruction</a> </div>
Reid Spencera89fb182006-11-09 21:18:01 +0000[diff] [blame]2634<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2635<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2636<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]2637 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]2638</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2639<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2640<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2641<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2642<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2643to 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]2644operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2645operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2646optimizer is not allowed to modify the number or order of execution of
2647this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2648 href="#i_store">store</a></tt> instructions.</p>
2649<h5>Semantics:</h5>
2650<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2651at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2652<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2653<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2654 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2655 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2656 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2657</pre>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2658</div>
2659
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2660<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2661<div class="doc_subsubsection">
2662 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2663</div>
2664
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2665<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2666<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2667<pre>
2668 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2669</pre>
2670
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2671<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2672
2673<p>
2674The '<tt>getelementptr</tt>' instruction is used to get the address of a
2675subelement of an aggregate data structure.</p>
2676
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2677<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2678
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2679<p>This instruction takes a list of integer operands that indicate what
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2680elements of the aggregate object to index to. The actual types of the arguments
2681provided depend on the type of the first pointer argument. The
2682'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2683levels 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]2684structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2685into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2686be sign extended to 64-bit values.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2687
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2688<p>For example, let's consider a C code fragment and how it gets
2689compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2690
2691<pre>
2692 struct RT {
2693 char A;
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2694 i32 B[10][20];
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2695 char C;
2696 };
2697 struct ST {
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2698 i32 X;
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2699 double Y;
2700 struct RT Z;
2701 };
2702
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2703 define i32 *foo(struct ST *s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2704 return &amp;s[1].Z.B[5][13];
2705 }
2706</pre>
2707
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2708<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2709
2710<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2711 %RT = type { i8 , [10 x [20 x i32]], i8 }
2712 %ST = type { i32, double, %RT }
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2713
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2714 define i32* %foo(%ST* %s) {
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2715 entry:
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2716 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2717 ret i32* %reg
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2718 }
2719</pre>
2720
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2721<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2722
2723<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2724on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2725and <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]2726<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]2727to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencerc0312692006-12-03 16:53:48 +0000[diff] [blame]2728<b>constants</b>.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2729
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2730<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]2731type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2732}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2733the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2734i8 }</tt>' type, another structure. The third index indexes into the second
2735element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2736array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2737'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2738to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2739
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2740<p>Note that it is perfectly legal to index partially through a
2741structure, returning a pointer to an inner element. Because of this,
2742the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2743
2744<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2745 define i32* %foo(%ST* %s) {
2746 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2747 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2748 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2749 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2750 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2751 ret i32* %t5
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2752 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2753</pre>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2754
2755<p>Note that it is undefined to access an array out of bounds: array and
2756pointer indexes must always be within the defined bounds of the array type.
2757The one exception for this rules is zero length arrays. These arrays are
2758defined to be accessible as variable length arrays, which requires access
2759beyond the zero'th element.</p>
2760
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2761<p>The getelementptr instruction is often confusing. For some more insight
2762into how it works, see <a href="GetElementPtr.html">the getelementptr
2763FAQ</a>.</p>
2764
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2765<h5>Example:</h5>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2766
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2767<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2768 <i>; yields [12 x i8]*:aptr</i>
2769 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2770</pre>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2771</div>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2772
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2773<!-- ======================================================================= -->
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2774<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2775</div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2776<div class="doc_text">
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2777<p>The instructions in this category are the conversion instructions (casting)
2778which all take a single operand and a type. They perform various bit conversions
2779on the operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2780</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2781
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2782<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2783<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2784 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2785</div>
2786<div class="doc_text">
2787
2788<h5>Syntax:</h5>
2789<pre>
2790 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2791</pre>
2792
2793<h5>Overview:</h5>
2794<p>
2795The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2796</p>
2797
2798<h5>Arguments:</h5>
2799<p>
2800The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2801be 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]2802and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2803type. The bit size of <tt>value</tt> must be larger than the bit size of
2804<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2805
2806<h5>Semantics:</h5>
2807<p>
2808The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2809and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2810larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2811It will always truncate bits.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2812
2813<h5>Example:</h5>
2814<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2815 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2816 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2817 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2818</pre>
2819</div>
2820
2821<!-- _______________________________________________________________________ -->
2822<div class="doc_subsubsection">
2823 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2824</div>
2825<div class="doc_text">
2826
2827<h5>Syntax:</h5>
2828<pre>
2829 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2830</pre>
2831
2832<h5>Overview:</h5>
2833<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2834<tt>ty2</tt>.</p>
2835
2836
2837<h5>Arguments:</h5>
2838<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]2839<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2840also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2841<tt>value</tt> must be smaller than the bit size of the destination type,
2842<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2843
2844<h5>Semantics:</h5>
2845<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2846bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2847the operand and the type are the same size, no bit filling is done and the
2848cast is considered a <i>no-op cast</i> because no bits change (only the type
2849changes).</p>
2850
Reid Spencer07c9c682007-01-12 15:46:11 +0000[diff] [blame]2851<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]2852
2853<h5>Example:</h5>
2854<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2855 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2856 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2857</pre>
2858</div>
2859
2860<!-- _______________________________________________________________________ -->
2861<div class="doc_subsubsection">
2862 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2863</div>
2864<div class="doc_text">
2865
2866<h5>Syntax:</h5>
2867<pre>
2868 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2869</pre>
2870
2871<h5>Overview:</h5>
2872<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2873
2874<h5>Arguments:</h5>
2875<p>
2876The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2877<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2878also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2879<tt>value</tt> must be smaller than the bit size of the destination type,
2880<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2881
2882<h5>Semantics:</h5>
2883<p>
2884The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2885bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2886the type <tt>ty2</tt>. When the the operand and the type are the same size,
2887no bit filling is done and the cast is considered a <i>no-op cast</i> because
2888no bits change (only the type changes).</p>
2889
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2890<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]2891
2892<h5>Example:</h5>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2893<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2894 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2895 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2896</pre>
2897</div>
2898
2899<!-- _______________________________________________________________________ -->
2900<div class="doc_subsubsection">
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2901 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2902</div>
2903
2904<div class="doc_text">
2905
2906<h5>Syntax:</h5>
2907
2908<pre>
2909 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2910</pre>
2911
2912<h5>Overview:</h5>
2913<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2914<tt>ty2</tt>.</p>
2915
2916
2917<h5>Arguments:</h5>
2918<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2919 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2920cast it to. The size of <tt>value</tt> must be larger than the size of
2921<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2922<i>no-op cast</i>.</p>
2923
2924<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2925<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2926<a href="#t_floating">floating point</a> type to a smaller
2927<a href="#t_floating">floating point</a> type. If the value cannot fit within
2928the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2929
2930<h5>Example:</h5>
2931<pre>
2932 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2933 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2934</pre>
2935</div>
2936
2937<!-- _______________________________________________________________________ -->
2938<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2939 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2940</div>
2941<div class="doc_text">
2942
2943<h5>Syntax:</h5>
2944<pre>
2945 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2946</pre>
2947
2948<h5>Overview:</h5>
2949<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2950floating point value.</p>
2951
2952<h5>Arguments:</h5>
2953<p>The '<tt>fpext</tt>' instruction takes a
2954<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2955and a <a href="#t_floating">floating point</a> type to cast it to. The source
2956type must be smaller than the destination type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2957
2958<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2959<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]2960<a href="#t_floating">floating point</a> type to a larger
2961<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2962used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]2963<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]2964
2965<h5>Example:</h5>
2966<pre>
2967 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2968 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2969</pre>
2970</div>
2971
2972<!-- _______________________________________________________________________ -->
2973<div class="doc_subsubsection">
Reid Spencer2eadb532007-01-21 00:29:26 +0000[diff] [blame]2974 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2975</div>
2976<div class="doc_text">
2977
2978<h5>Syntax:</h5>
2979<pre>
2980 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2981</pre>
2982
2983<h5>Overview:</h5>
2984<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2985unsigned integer equivalent of type <tt>ty2</tt>.
2986</p>
2987
2988<h5>Arguments:</h5>
2989<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2990<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]2991must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2992
2993<h5>Semantics:</h5>
2994<p> The '<tt>fp2uint</tt>' instruction converts its
2995<a href="#t_floating">floating point</a> operand into the nearest (rounding
2996towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2997the results are undefined.</p>
2998
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2999<p>When converting to i1, the conversion is done as a comparison against
3000zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3001If 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]3002
3003<h5>Example:</h5>
3004<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3005 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
3006 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3007 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3008</pre>
3009</div>
3010
3011<!-- _______________________________________________________________________ -->
3012<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3013 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3014</div>
3015<div class="doc_text">
3016
3017<h5>Syntax:</h5>
3018<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3019 &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]3020</pre>
3021
3022<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3023<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3024<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]3025</p>
3026
3027
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3028<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3029<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]3030<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]3031must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3032
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3033<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3034<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3035<a href="#t_floating">floating point</a> operand into the nearest (rounding
3036towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3037the results are undefined.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3038
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3039<p>When converting to i1, the conversion is done as a comparison against
3040zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
3041If 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]3042
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3043<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3044<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3045 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
3046 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3047 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3048</pre>
3049</div>
3050
3051<!-- _______________________________________________________________________ -->
3052<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3053 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3054</div>
3055<div class="doc_text">
3056
3057<h5>Syntax:</h5>
3058<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3059 &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]3060</pre>
3061
3062<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3063<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3064integer and converts that value to the <tt>ty2</tt> type.</p>
3065
3066
3067<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3068<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]3069<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]3070be a <a href="#t_floating">floating point</a> type.</p>
3071
3072<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3073<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3074integer quantity and converts it to the corresponding floating point value. If
3075the value cannot fit in the floating point value, the results are undefined.</p>
3076
3077
3078<h5>Example:</h5>
3079<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3080 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3081 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3082</pre>
3083</div>
3084
3085<!-- _______________________________________________________________________ -->
3086<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3087 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3088</div>
3089<div class="doc_text">
3090
3091<h5>Syntax:</h5>
3092<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3093 &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]3094</pre>
3095
3096<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3097<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3098integer and converts that value to the <tt>ty2</tt> type.</p>
3099
3100<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3101<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]3102<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]3103a <a href="#t_floating">floating point</a> type.</p>
3104
3105<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3106<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3107integer quantity and converts it to the corresponding floating point value. If
3108the value cannot fit in the floating point value, the results are undefined.</p>
3109
3110<h5>Example:</h5>
3111<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3112 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3113 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3114</pre>
3115</div>
3116
3117<!-- _______________________________________________________________________ -->
3118<div class="doc_subsubsection">
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3119 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3120</div>
3121<div class="doc_text">
3122
3123<h5>Syntax:</h5>
3124<pre>
3125 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3126</pre>
3127
3128<h5>Overview:</h5>
3129<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3130the integer type <tt>ty2</tt>.</p>
3131
3132<h5>Arguments:</h5>
3133<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3134must 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]3135<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3136
3137<h5>Semantics:</h5>
3138<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3139<tt>ty2</tt> by interpreting the pointer value as an integer and either
3140truncating or zero extending that value to the size of the integer type. If
3141<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3142<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3143are the same size, then nothing is done (<i>no-op cast</i>).</p>
3144
3145<h5>Example:</h5>
3146<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3147 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3148 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3149</pre>
3150</div>
3151
3152<!-- _______________________________________________________________________ -->
3153<div class="doc_subsubsection">
3154 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3155</div>
3156<div class="doc_text">
3157
3158<h5>Syntax:</h5>
3159<pre>
3160 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3161</pre>
3162
3163<h5>Overview:</h5>
3164<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3165a pointer type, <tt>ty2</tt>.</p>
3166
3167<h5>Arguments:</h5>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3168<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3169value to cast, and a type to cast it to, which must be a
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]3170<a href="#t_pointer">pointer</a> type.
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3171
3172<h5>Semantics:</h5>
3173<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3174<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3175the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3176size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3177the size of a pointer then a zero extension is done. If they are the same size,
3178nothing is done (<i>no-op cast</i>).</p>
3179
3180<h5>Example:</h5>
3181<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3182 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3183 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3184 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3185</pre>
3186</div>
3187
3188<!-- _______________________________________________________________________ -->
3189<div class="doc_subsubsection">
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3190 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3191</div>
3192<div class="doc_text">
3193
3194<h5>Syntax:</h5>
3195<pre>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3196 &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]3197</pre>
3198
3199<h5>Overview:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3200<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3201<tt>ty2</tt> without changing any bits.</p>
3202
3203<h5>Arguments:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3204<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3205a first class value, and a type to cast it to, which must also be a <a
3206 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencere3db84c2007-01-09 20:08:58 +0000[diff] [blame]3207and the destination type, <tt>ty2</tt>, must be identical. If the source
3208type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3209
3210<h5>Semantics:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3211<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3212<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3213this conversion. The conversion is done as if the <tt>value</tt> had been
3214stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3215converted to other pointer types with this instruction. To convert pointers to
3216other types, use the <a href="#i_inttoptr">inttoptr</a> or
3217<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3218
3219<h5>Example:</h5>
3220<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3221 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3222 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3223 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3224</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3225</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3226
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3227<!-- ======================================================================= -->
3228<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3229<div class="doc_text">
3230<p>The instructions in this category are the "miscellaneous"
3231instructions, which defy better classification.</p>
3232</div>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3233
3234<!-- _______________________________________________________________________ -->
3235<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3236</div>
3237<div class="doc_text">
3238<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3239<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3240<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3241</pre>
3242<h5>Overview:</h5>
3243<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3244of its two integer operands.</p>
3245<h5>Arguments:</h5>
3246<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3247the condition code which indicates the kind of comparison to perform. It is not
3248a value, just a keyword. The possibilities for the condition code are:
3249<ol>
3250 <li><tt>eq</tt>: equal</li>
3251 <li><tt>ne</tt>: not equal </li>
3252 <li><tt>ugt</tt>: unsigned greater than</li>
3253 <li><tt>uge</tt>: unsigned greater or equal</li>
3254 <li><tt>ult</tt>: unsigned less than</li>
3255 <li><tt>ule</tt>: unsigned less or equal</li>
3256 <li><tt>sgt</tt>: signed greater than</li>
3257 <li><tt>sge</tt>: signed greater or equal</li>
3258 <li><tt>slt</tt>: signed less than</li>
3259 <li><tt>sle</tt>: signed less or equal</li>
3260</ol>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3261<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3262<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3263<h5>Semantics:</h5>
3264<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3265the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3266yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3267<ol>
3268 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3269 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3270 </li>
3271 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3272 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3273 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3274 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3275 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3276 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3277 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3278 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3279 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3280 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3281 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3282 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3283 <li><tt>sge</tt>: interprets the operands as signed values and yields
3284 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3285 <li><tt>slt</tt>: interprets the operands as signed values and yields
3286 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3287 <li><tt>sle</tt>: interprets the operands as signed values and yields
3288 <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]3289</ol>
3290<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3291values are treated as integers and then compared.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3292
3293<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3294<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3295 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3296 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3297 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3298 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3299 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3300</pre>
3301</div>
3302
3303<!-- _______________________________________________________________________ -->
3304<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3305</div>
3306<div class="doc_text">
3307<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3308<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3309<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3310</pre>
3311<h5>Overview:</h5>
3312<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3313of its floating point operands.</p>
3314<h5>Arguments:</h5>
3315<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3316the condition code which indicates the kind of comparison to perform. It is not
3317a value, just a keyword. The possibilities for the condition code are:
3318<ol>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3319 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3320 <li><tt>oeq</tt>: ordered and equal</li>
3321 <li><tt>ogt</tt>: ordered and greater than </li>
3322 <li><tt>oge</tt>: ordered and greater than or equal</li>
3323 <li><tt>olt</tt>: ordered and less than </li>
3324 <li><tt>ole</tt>: ordered and less than or equal</li>
3325 <li><tt>one</tt>: ordered and not equal</li>
3326 <li><tt>ord</tt>: ordered (no nans)</li>
3327 <li><tt>ueq</tt>: unordered or equal</li>
3328 <li><tt>ugt</tt>: unordered or greater than </li>
3329 <li><tt>uge</tt>: unordered or greater than or equal</li>
3330 <li><tt>ult</tt>: unordered or less than </li>
3331 <li><tt>ule</tt>: unordered or less than or equal</li>
3332 <li><tt>une</tt>: unordered or not equal</li>
3333 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3334 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3335</ol>
Reid Spencer02e0d1d2006-12-06 07:08:07 +0000[diff] [blame]3336<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3337<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3338<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3339<a href="#t_floating">floating point</a> typed. They must have identical
3340types.</p>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3341<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3342<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3343<h5>Semantics:</h5>
3344<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3345the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3346yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3347<ol>
3348 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3349 <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]3350 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3351 <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]3352 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3353 <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]3354 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3355 <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]3356 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3357 <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]3358 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3359 <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]3360 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3361 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3362 <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]3363 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3364 <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]3365 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3366 <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]3367 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3368 <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]3369 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3370 <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]3371 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3372 <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]3373 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3374 <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]3375 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3376</ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3377
3378<h5>Example:</h5>
3379<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3380 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3381 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3382 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3383</pre>
3384</div>
3385
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3386<!-- _______________________________________________________________________ -->
3387<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3388Instruction</a> </div>
3389<div class="doc_text">
3390<h5>Syntax:</h5>
3391<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3392<h5>Overview:</h5>
3393<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3394the SSA graph representing the function.</p>
3395<h5>Arguments:</h5>
3396<p>The type of the incoming values are specified with the first type
3397field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3398as arguments, with one pair for each predecessor basic block of the
3399current block. Only values of <a href="#t_firstclass">first class</a>
3400type may be used as the value arguments to the PHI node. Only labels
3401may be used as the label arguments.</p>
3402<p>There must be no non-phi instructions between the start of a basic
3403block and the PHI instructions: i.e. PHI instructions must be first in
3404a basic block.</p>
3405<h5>Semantics:</h5>
3406<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3407value specified by the parameter, depending on which basic block we
3408came from in the last <a href="#terminators">terminator</a> instruction.</p>
3409<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3410<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]3411</div>
3412
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3413<!-- _______________________________________________________________________ -->
3414<div class="doc_subsubsection">
3415 <a name="i_select">'<tt>select</tt>' Instruction</a>
3416</div>
3417
3418<div class="doc_text">
3419
3420<h5>Syntax:</h5>
3421
3422<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3423 &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]3424</pre>
3425
3426<h5>Overview:</h5>
3427
3428<p>
3429The '<tt>select</tt>' instruction is used to choose one value based on a
3430condition, without branching.
3431</p>
3432
3433
3434<h5>Arguments:</h5>
3435
3436<p>
3437The '<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.
3438</p>
3439
3440<h5>Semantics:</h5>
3441
3442<p>
3443If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3444value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3445</p>
3446
3447<h5>Example:</h5>
3448
3449<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3450 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3451</pre>
3452</div>
3453
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]3454
3455<!-- _______________________________________________________________________ -->
3456<div class="doc_subsubsection">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3457 <a name="i_call">'<tt>call</tt>' Instruction</a>
3458</div>
3459
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3460<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3461
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3462<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3463<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3464 &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]3465</pre>
3466
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3467<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3468
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3469<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3470
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3471<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3472
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3473<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3474
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3475<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3476 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3477 <p>The optional "tail" marker indicates whether the callee function accesses
3478 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3479 function call is eligible for tail call optimization. Note that calls may
3480 be marked "tail" even if they do not occur before a <a
3481 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3482 </li>
3483 <li>
Duncan Sands16f122e2007-03-30 12:22:09 +0000[diff] [blame]3484 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3485 convention</a> the call should use. If none is specified, the call defaults
3486 to using C calling conventions.
3487 </li>
3488 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3489 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3490 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3491 signature. This type can be omitted if the function is not varargs and
3492 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3493 </li>
3494 <li>
3495 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3496 be invoked. In most cases, this is a direct function invocation, but
3497 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3498 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3499 </li>
3500 <li>
3501 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]3502 function signature argument types. All arguments must be of
3503 <a href="#t_firstclass">first class</a> type. If the function signature
3504 indicates the function accepts a variable number of arguments, the extra
3505 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3506 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3507</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3508
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3509<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3510
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3511<p>The '<tt>call</tt>' instruction is used to cause control flow to
3512transfer to a specified function, with its incoming arguments bound to
3513the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3514instruction in the called function, control flow continues with the
3515instruction after the function call, and the return value of the
3516function is bound to the result argument. This is a simpler case of
3517the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3518
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3519<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3520
3521<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3522 %retval = call i32 %test(i32 %argc)
3523 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3524 %X = tail call i32 %foo()
3525 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3526</pre>
3527
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3528</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3529
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3530<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3531<div class="doc_subsubsection">
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3532 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3533</div>
3534
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3535<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3536
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3537<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3538
3539<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3540 &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]3541</pre>
3542
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3543<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3544
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3545<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3546the "variable argument" area of a function call. It is used to implement the
3547<tt>va_arg</tt> macro in C.</p>
3548
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3549<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3550
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3551<p>This instruction takes a <tt>va_list*</tt> value and the type of
3552the argument. It returns a value of the specified argument type and
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]3553increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3554actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3555
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3556<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3557
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3558<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3559type from the specified <tt>va_list</tt> and causes the
3560<tt>va_list</tt> to point to the next argument. For more information,
3561see the variable argument handling <a href="#int_varargs">Intrinsic
3562Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3563
3564<p>It is legal for this instruction to be called in a function which does not
3565take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3566function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3567
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3568<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3569href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3570argument.</p>
3571
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3572<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3573
3574<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3575
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3576</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3577
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3578<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3579<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3580<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3581
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3582<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3583
3584<p>LLVM supports the notion of an "intrinsic function". These functions have
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3585well known names and semantics and are required to follow certain restrictions.
3586Overall, these intrinsics represent an extension mechanism for the LLVM
3587language that does not require changing all of the transformations in LLVM to
3588add to the language (or the bytecode reader/writer, the parser,
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3589etc...).</p>
3590
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3591<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3592prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3593this. Intrinsic functions must always be external functions: you cannot define
3594the body of intrinsic functions. Intrinsic functions may only be used in call
3595or invoke instructions: it is illegal to take the address of an intrinsic
3596function. Additionally, because intrinsic functions are part of the LLVM
3597language, it is required that they all be documented here if any are added.</p>
3598
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3599<p>Some intrinsic functions can be overloaded. That is, the intrinsic represents
3600a family of functions that perform the same operation but on different data
3601types. This is most frequent with the integer types. Since LLVM can represent
3602over 8 million different integer types, there is a way to declare an intrinsic
3603that can be overloaded based on its arguments. Such intrinsics will have the
3604names of the arbitrary types encoded into the intrinsic function name, each
3605preceded by a period. For example, the <tt>llvm.ctpop</tt> function can take an
3606integer of any width. This leads to a family of functions such as
3607<tt>i32 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i32 @llvm.ctpop.i29(i29 %val)</tt>.
3608</p>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3609
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]3610
3611<p>To learn how to add an intrinsic function, please see the
3612<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3613</p>
3614
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3615</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3616
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3617<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3618<div class="doc_subsection">
3619 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3620</div>
3621
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3622<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3623
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3624<p>Variable argument support is defined in LLVM with the <a
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3625 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3626intrinsic functions. These functions are related to the similarly
3627named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3628
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3629<p>All of these functions operate on arguments that use a
3630target-specific value type "<tt>va_list</tt>". The LLVM assembly
3631language reference manual does not define what this type is, so all
3632transformations should be prepared to handle intrinsics with any type
3633used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3634
Chris Lattner30b868d2006-05-15 17:26:46 +0000[diff] [blame]3635<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]3636instruction and the variable argument handling intrinsic functions are
3637used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3638
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3639<pre>
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3640define i32 @test(i32 %X, ...) {
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3641 ; Initialize variable argument processing
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3642 %ap = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3643 %ap2 = bitcast i8** %ap to i8*
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3644 call void @llvm.va_start(i8* %ap2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3645
3646 ; Read a single integer argument
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3647 %tmp = va_arg i8 ** %ap, i32
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3648
3649 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3650 %aq = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3651 %aq2 = bitcast i8** %aq to i8*
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3652 call void @llvm.va_copy(i8 *%aq2, i8* %ap2)
3653 call void @llvm.va_end(i8* %aq2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3654
3655 ; Stop processing of arguments.
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3656 call void @llvm.va_end(i8* %ap2)
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3657 ret i32 %tmp
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3658}
Anton Korobeynikov640bbe02007-03-21 23:58:04 +0000[diff] [blame]3659
3660declare void @llvm.va_start(i8*)
3661declare void @llvm.va_copy(i8*, i8*)
3662declare void @llvm.va_end(i8*)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3663</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3664</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3665
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3666<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3667<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3668 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3669</div>
3670
3671
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3672<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3673<h5>Syntax:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3674<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3675<h5>Overview:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3676<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3677<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3678href="#i_va_arg">va_arg</a></tt>.</p>
3679
3680<h5>Arguments:</h5>
3681
3682<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3683
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3684<h5>Semantics:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3685
3686<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3687macro available in C. In a target-dependent way, it initializes the
3688<tt>va_list</tt> element the argument points to, so that the next call to
3689<tt>va_arg</tt> will produce the first variable argument passed to the function.
3690Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3691last argument of the function, the compiler can figure that out.</p>
3692
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3693</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3694
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3695<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3696<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3697 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3698</div>
3699
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3700<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3701<h5>Syntax:</h5>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3702<pre> declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3703<h5>Overview:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3704
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3705<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3706which 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]3707or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3708
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3709<h5>Arguments:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3710
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3711<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3712
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3713<h5>Semantics:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3714
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3715<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]3716macro 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]3717Calls to <a href="#int_va_start"><tt>llvm.va_start</tt></a> and <a
3718 href="#int_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3719with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3720
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3721</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3722
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3723<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3724<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3725 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3726</div>
3727
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3728<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3729
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3730<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3731
3732<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3733 declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3734</pre>
3735
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3736<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3737
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3738<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3739the source argument list to the destination argument list.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3740
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3741<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3742
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3743<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]3744The 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]3745
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3746
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3747<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3748
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3749<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3750available in C. In a target-dependent way, it copies the source
3751<tt>va_list</tt> element into the destination list. This intrinsic is necessary
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3752because 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]3753arbitrarily complex and require memory allocation, for example.</p>
3754
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3755</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3756
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3757<!-- ======================================================================= -->
3758<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3759 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3760</div>
3761
3762<div class="doc_text">
3763
3764<p>
3765LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3766Collection</a> requires the implementation and generation of these intrinsics.
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3767These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3768stack</a>, as well as garbage collector implementations that require <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3769href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3770Front-ends for type-safe garbage collected languages should generate these
3771intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3772href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3773</p>
3774</div>
3775
3776<!-- _______________________________________________________________________ -->
3777<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3778 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3779</div>
3780
3781<div class="doc_text">
3782
3783<h5>Syntax:</h5>
3784
3785<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3786 declare void @llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3787</pre>
3788
3789<h5>Overview:</h5>
3790
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]3791<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]3792the code generator, and allows some metadata to be associated with it.</p>
3793
3794<h5>Arguments:</h5>
3795
3796<p>The first argument specifies the address of a stack object that contains the
3797root pointer. The second pointer (which must be either a constant or a global
3798value address) contains the meta-data to be associated with the root.</p>
3799
3800<h5>Semantics:</h5>
3801
3802<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3803location. At compile-time, the code generator generates information to allow
3804the runtime to find the pointer at GC safe points.
3805</p>
3806
3807</div>
3808
3809
3810<!-- _______________________________________________________________________ -->
3811<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3812 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3813</div>
3814
3815<div class="doc_text">
3816
3817<h5>Syntax:</h5>
3818
3819<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3820 declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3821</pre>
3822
3823<h5>Overview:</h5>
3824
3825<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3826locations, allowing garbage collector implementations that require read
3827barriers.</p>
3828
3829<h5>Arguments:</h5>
3830
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3831<p>The second argument is the address to read from, which should be an address
3832allocated from the garbage collector. The first object is a pointer to the
3833start of the referenced object, if needed by the language runtime (otherwise
3834null).</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3835
3836<h5>Semantics:</h5>
3837
3838<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3839instruction, but may be replaced with substantially more complex code by the
3840garbage collector runtime, as needed.</p>
3841
3842</div>
3843
3844
3845<!-- _______________________________________________________________________ -->
3846<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3847 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3848</div>
3849
3850<div class="doc_text">
3851
3852<h5>Syntax:</h5>
3853
3854<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3855 declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3856</pre>
3857
3858<h5>Overview:</h5>
3859
3860<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3861locations, allowing garbage collector implementations that require write
3862barriers (such as generational or reference counting collectors).</p>
3863
3864<h5>Arguments:</h5>
3865
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3866<p>The first argument is the reference to store, the second is the start of the
3867object to store it to, and the third is the address of the field of Obj to
3868store to. If the runtime does not require a pointer to the object, Obj may be
3869null.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3870
3871<h5>Semantics:</h5>
3872
3873<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3874instruction, but may be replaced with substantially more complex code by the
3875garbage collector runtime, as needed.</p>
3876
3877</div>
3878
3879
3880
3881<!-- ======================================================================= -->
3882<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3883 <a name="int_codegen">Code Generator Intrinsics</a>
3884</div>
3885
3886<div class="doc_text">
3887<p>
3888These intrinsics are provided by LLVM to expose special features that may only
3889be implemented with code generator support.
3890</p>
3891
3892</div>
3893
3894<!-- _______________________________________________________________________ -->
3895<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3896 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3897</div>
3898
3899<div class="doc_text">
3900
3901<h5>Syntax:</h5>
3902<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3903 declare i8 *@llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3904</pre>
3905
3906<h5>Overview:</h5>
3907
3908<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3909The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3910target-specific value indicating the return address of the current function
3911or one of its callers.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3912</p>
3913
3914<h5>Arguments:</h5>
3915
3916<p>
3917The argument to this intrinsic indicates which function to return the address
3918for. Zero indicates the calling function, one indicates its caller, etc. The
3919argument is <b>required</b> to be a constant integer value.
3920</p>
3921
3922<h5>Semantics:</h5>
3923
3924<p>
3925The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3926the return address of the specified call frame, or zero if it cannot be
3927identified. The value returned by this intrinsic is likely to be incorrect or 0
3928for arguments other than zero, so it should only be used for debugging purposes.
3929</p>
3930
3931<p>
3932Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3933aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3934source-language caller.
3935</p>
3936</div>
3937
3938
3939<!-- _______________________________________________________________________ -->
3940<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3941 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3942</div>
3943
3944<div class="doc_text">
3945
3946<h5>Syntax:</h5>
3947<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3948 declare i8 *@llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3949</pre>
3950
3951<h5>Overview:</h5>
3952
3953<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3954The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3955target-specific frame pointer value for the specified stack frame.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3956</p>
3957
3958<h5>Arguments:</h5>
3959
3960<p>
3961The argument to this intrinsic indicates which function to return the frame
3962pointer for. Zero indicates the calling function, one indicates its caller,
3963etc. The argument is <b>required</b> to be a constant integer value.
3964</p>
3965
3966<h5>Semantics:</h5>
3967
3968<p>
3969The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3970the frame address of the specified call frame, or zero if it cannot be
3971identified. The value returned by this intrinsic is likely to be incorrect or 0
3972for arguments other than zero, so it should only be used for debugging purposes.
3973</p>
3974
3975<p>
3976Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3977aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3978source-language caller.
3979</p>
3980</div>
3981
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3982<!-- _______________________________________________________________________ -->
3983<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3984 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3985</div>
3986
3987<div class="doc_text">
3988
3989<h5>Syntax:</h5>
3990<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]3991 declare i8 *@llvm.stacksave()
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3992</pre>
3993
3994<h5>Overview:</h5>
3995
3996<p>
3997The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]3998the function stack, for use with <a href="#int_stackrestore">
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3999<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4000features like scoped automatic variable sized arrays in C99.
4001</p>
4002
4003<h5>Semantics:</h5>
4004
4005<p>
4006This intrinsic returns a opaque pointer value that can be passed to <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4007href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4008<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4009<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4010state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4011practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4012that were allocated after the <tt>llvm.stacksave</tt> was executed.
4013</p>
4014
4015</div>
4016
4017<!-- _______________________________________________________________________ -->
4018<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4019 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4020</div>
4021
4022<div class="doc_text">
4023
4024<h5>Syntax:</h5>
4025<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4026 declare void @llvm.stackrestore(i8 * %ptr)
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4027</pre>
4028
4029<h5>Overview:</h5>
4030
4031<p>
4032The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4033the function stack to the state it was in when the corresponding <a
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4034href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4035useful for implementing language features like scoped automatic variable sized
4036arrays in C99.
4037</p>
4038
4039<h5>Semantics:</h5>
4040
4041<p>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4042See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]4043</p>
4044
4045</div>
4046
4047
4048<!-- _______________________________________________________________________ -->
4049<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4050 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4051</div>
4052
4053<div class="doc_text">
4054
4055<h5>Syntax:</h5>
4056<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4057 declare void @llvm.prefetch(i8 * &lt;address&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4058 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4059</pre>
4060
4061<h5>Overview:</h5>
4062
4063
4064<p>
4065The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4066a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4067no
4068effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]4069characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4070</p>
4071
4072<h5>Arguments:</h5>
4073
4074<p>
4075<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4076determining if the fetch should be for a read (0) or write (1), and
4077<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]4078locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]4079<tt>locality</tt> arguments must be constant integers.
4080</p>
4081
4082<h5>Semantics:</h5>
4083
4084<p>
4085This intrinsic does not modify the behavior of the program. In particular,
4086prefetches cannot trap and do not produce a value. On targets that support this
4087intrinsic, the prefetch can provide hints to the processor cache for better
4088performance.
4089</p>
4090
4091</div>
4092
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4093<!-- _______________________________________________________________________ -->
4094<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4095 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4096</div>
4097
4098<div class="doc_text">
4099
4100<h5>Syntax:</h5>
4101<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4102 declare void @llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4103</pre>
4104
4105<h5>Overview:</h5>
4106
4107
4108<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4109The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4110(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4111code to simulators and other tools. The method is target specific, but it is
4112expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]4113The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnere64d41d2005-11-15 06:07:55 +0000[diff] [blame]4114after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb40261e2006-03-24 07:16:10 +0000[diff] [blame]4115optimizations. The intended use is to be inserted after optimizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4116correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4117</p>
4118
4119<h5>Arguments:</h5>
4120
4121<p>
4122<tt>id</tt> is a numerical id identifying the marker.
4123</p>
4124
4125<h5>Semantics:</h5>
4126
4127<p>
4128This intrinsic does not modify the behavior of the program. Backends that do not
4129support this intrinisic may ignore it.
4130</p>
4131
4132</div>
4133
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4134<!-- _______________________________________________________________________ -->
4135<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4136 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4137</div>
4138
4139<div class="doc_text">
4140
4141<h5>Syntax:</h5>
4142<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4143 declare i64 @llvm.readcyclecounter( )
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4144</pre>
4145
4146<h5>Overview:</h5>
4147
4148
4149<p>
4150The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4151counter register (or similar low latency, high accuracy clocks) on those targets
4152that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4153As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4154should only be used for small timings.
4155</p>
4156
4157<h5>Semantics:</h5>
4158
4159<p>
4160When directly supported, reading the cycle counter should not modify any memory.
4161Implementations are allowed to either return a application specific value or a
4162system wide value. On backends without support, this is lowered to a constant 0.
4163</p>
4164
4165</div>
4166
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4167<!-- ======================================================================= -->
4168<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4169 <a name="int_libc">Standard C Library Intrinsics</a>
4170</div>
4171
4172<div class="doc_text">
4173<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4174LLVM provides intrinsics for a few important standard C library functions.
4175These intrinsics allow source-language front-ends to pass information about the
4176alignment of the pointer arguments to the code generator, providing opportunity
4177for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4178</p>
4179
4180</div>
4181
4182<!-- _______________________________________________________________________ -->
4183<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4184 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4185</div>
4186
4187<div class="doc_text">
4188
4189<h5>Syntax:</h5>
4190<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4191 declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4192 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4193 declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4194 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4195</pre>
4196
4197<h5>Overview:</h5>
4198
4199<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4200The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4201location to the destination location.
4202</p>
4203
4204<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4205Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4206intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4207</p>
4208
4209<h5>Arguments:</h5>
4210
4211<p>
4212The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4213the source. The third argument is an integer argument
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4214specifying the number of bytes to copy, and the fourth argument is the alignment
4215of the source and destination locations.
4216</p>
4217
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4218<p>
4219If 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]4220the caller guarantees that both the source and destination pointers are aligned
4221to that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4222</p>
4223
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4224<h5>Semantics:</h5>
4225
4226<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4227The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4228location to the destination location, which are not allowed to overlap. It
4229copies "len" bytes of memory over. If the argument is known to be aligned to
4230some boundary, this can be specified as the fourth argument, otherwise it should
4231be set to 0 or 1.
4232</p>
4233</div>
4234
4235
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4236<!-- _______________________________________________________________________ -->
4237<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4238 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4239</div>
4240
4241<div class="doc_text">
4242
4243<h5>Syntax:</h5>
4244<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4245 declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4246 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4247 declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4248 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4249</pre>
4250
4251<h5>Overview:</h5>
4252
4253<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4254The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4255location to the destination location. It is similar to the
4256'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4257</p>
4258
4259<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4260Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4261intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4262</p>
4263
4264<h5>Arguments:</h5>
4265
4266<p>
4267The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4268the source. The third argument is an integer argument
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4269specifying the number of bytes to copy, and the fourth argument is the alignment
4270of the source and destination locations.
4271</p>
4272
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4273<p>
4274If 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]4275the caller guarantees that the source and destination pointers are aligned to
4276that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4277</p>
4278
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4279<h5>Semantics:</h5>
4280
4281<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4282The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4283location to the destination location, which may overlap. It
4284copies "len" bytes of memory over. If the argument is known to be aligned to
4285some boundary, this can be specified as the fourth argument, otherwise it should
4286be set to 0 or 1.
4287</p>
4288</div>
4289
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4290
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4291<!-- _______________________________________________________________________ -->
4292<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4293 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4294</div>
4295
4296<div class="doc_text">
4297
4298<h5>Syntax:</h5>
4299<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4300 declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4301 i32 &lt;len&gt;, i32 &lt;align&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4302 declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4303 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4304</pre>
4305
4306<h5>Overview:</h5>
4307
4308<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4309The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4310byte value.
4311</p>
4312
4313<p>
4314Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4315does not return a value, and takes an extra alignment argument.
4316</p>
4317
4318<h5>Arguments:</h5>
4319
4320<p>
4321The first argument is a pointer to the destination to fill, the second is the
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4322byte value to fill it with, the third argument is an integer
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4323argument specifying the number of bytes to fill, and the fourth argument is the
4324known alignment of destination location.
4325</p>
4326
4327<p>
4328If 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]4329the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4330</p>
4331
4332<h5>Semantics:</h5>
4333
4334<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4335The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4336the
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4337destination location. If the argument is known to be aligned to some boundary,
4338this can be specified as the fourth argument, otherwise it should be set to 0 or
43391.
4340</p>
4341</div>
4342
4343
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4344<!-- _______________________________________________________________________ -->
4345<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4346 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4347</div>
4348
4349<div class="doc_text">
4350
4351<h5>Syntax:</h5>
4352<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4353 declare float @llvm.sqrt.f32(float %Val)
4354 declare double @llvm.sqrt.f64(double %Val)
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4355</pre>
4356
4357<h5>Overview:</h5>
4358
4359<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4360The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4361returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4362<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4363negative numbers (which allows for better optimization).
4364</p>
4365
4366<h5>Arguments:</h5>
4367
4368<p>
4369The argument and return value are floating point numbers of the same type.
4370</p>
4371
4372<h5>Semantics:</h5>
4373
4374<p>
4375This function returns the sqrt of the specified operand if it is a positive
4376floating point number.
4377</p>
4378</div>
4379
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4380<!-- _______________________________________________________________________ -->
4381<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4382 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4383</div>
4384
4385<div class="doc_text">
4386
4387<h5>Syntax:</h5>
4388<pre>
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4389 declare float @llvm.powi.f32(float %Val, i32 %power)
4390 declare double @llvm.powi.f64(double %Val, i32 %power)
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4391</pre>
4392
4393<h5>Overview:</h5>
4394
4395<p>
4396The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4397specified (positive or negative) power. The order of evaluation of
4398multiplications is not defined.
4399</p>
4400
4401<h5>Arguments:</h5>
4402
4403<p>
4404The second argument is an integer power, and the first is a value to raise to
4405that power.
4406</p>
4407
4408<h5>Semantics:</h5>
4409
4410<p>
4411This function returns the first value raised to the second power with an
4412unspecified sequence of rounding operations.</p>
4413</div>
4414
4415
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4416<!-- ======================================================================= -->
4417<div class="doc_subsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4418 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4419</div>
4420
4421<div class="doc_text">
4422<p>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4423LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4424These allow efficient code generation for some algorithms.
4425</p>
4426
4427</div>
4428
4429<!-- _______________________________________________________________________ -->
4430<div class="doc_subsubsection">
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4431 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4432</div>
4433
4434<div class="doc_text">
4435
4436<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4437<p>This is an overloaded intrinsic function. You can use bswap on any integer
4438type that is an even number of bytes (i.e. BitWidth % 16 == 0). Note the suffix
4439that includes the type for the result and the operand.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4440<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4441 declare i16 @llvm.bswap.i16.i16(i16 &lt;id&gt;)
4442 declare i32 @llvm.bswap.i32.i32(i32 &lt;id&gt;)
Reid Spencer403a1c42007-04-02 00:19:52 +0000[diff] [blame]4443 declare i64 @llvm.bswap.i64.i64(i64 &lt;id&gt;)
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4444</pre>
4445
4446<h5>Overview:</h5>
4447
4448<p>
Reid Spencerf361c4f2007-04-02 02:25:19 +0000[diff] [blame]4449The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4450values with an even number of bytes (positive multiple of 16 bits). These are
4451useful for performing operations on data that is not in the target's native
4452byte order.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4453</p>
4454
4455<h5>Semantics:</h5>
4456
4457<p>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4458The <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]4459and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4460intrinsic returns an i32 value that has the four bytes of the input i32
4461swapped, 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]4462i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48.i48</tt>,
4463<tt>llvm.bswap.i64.i64</tt> and other intrinsics extend this concept to
4464additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4465</p>
4466
4467</div>
4468
4469<!-- _______________________________________________________________________ -->
4470<div class="doc_subsubsection">
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4471 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4472</div>
4473
4474<div class="doc_text">
4475
4476<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4477<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
4478width. Not all targets support all bit widths however.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4479<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4480 declare i32 @llvm.ctpop.i8 (i8 &lt;src&gt;)
4481 declare i32 @llvm.ctpop.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4482 declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4483 declare i32 @llvm.ctpop.i64(i64 &lt;src&gt;)
4484 declare i32 @llvm.ctpop.i256(i256 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4485</pre>
4486
4487<h5>Overview:</h5>
4488
4489<p>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]4490The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4491value.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4492</p>
4493
4494<h5>Arguments:</h5>
4495
4496<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4497The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4498integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4499</p>
4500
4501<h5>Semantics:</h5>
4502
4503<p>
4504The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4505</p>
4506</div>
4507
4508<!-- _______________________________________________________________________ -->
4509<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4510 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4511</div>
4512
4513<div class="doc_text">
4514
4515<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4516<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
4517integer bit width. Not all targets support all bit widths however.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4518<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4519 declare i32 @llvm.ctlz.i8 (i8 &lt;src&gt;)
4520 declare i32 @llvm.ctlz.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4521 declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4522 declare i32 @llvm.ctlz.i64(i64 &lt;src&gt;)
4523 declare i32 @llvm.ctlz.i256(i256 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4524</pre>
4525
4526<h5>Overview:</h5>
4527
4528<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4529The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4530leading zeros in a variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4531</p>
4532
4533<h5>Arguments:</h5>
4534
4535<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4536The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4537integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4538</p>
4539
4540<h5>Semantics:</h5>
4541
4542<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4543The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4544in 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]4545of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4546</p>
4547</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4548
4549
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4550
4551<!-- _______________________________________________________________________ -->
4552<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4553 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4554</div>
4555
4556<div class="doc_text">
4557
4558<h5>Syntax:</h5>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4559<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
4560integer bit width. Not all targets support all bit widths however.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4561<pre>
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4562 declare i32 @llvm.cttz.i8 (i8 &lt;src&gt;)
4563 declare i32 @llvm.cttz.i16(i16 &lt;src&gt;)
Anton Korobeynikovbe9c93c2007-03-22 00:02:17 +0000[diff] [blame]4564 declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
Reid Spencer4eefaab2007-04-01 08:04:23 +0000[diff] [blame]4565 declare i32 @llvm.cttz.i64(i64 &lt;src&gt;)
4566 declare i32 @llvm.cttz.i256(i256 &lt;src&gt;)
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4567</pre>
4568
4569<h5>Overview:</h5>
4570
4571<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4572The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4573trailing zeros.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4574</p>
4575
4576<h5>Arguments:</h5>
4577
4578<p>
4579The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4580integer type. The return type must match the argument type.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4581</p>
4582
4583<h5>Semantics:</h5>
4584
4585<p>
4586The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4587in a variable. If the src == 0 then the result is the size in bits of the type
4588of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4589</p>
4590</div>
4591
Reid Spencer8a5799f2007-04-01 08:27:01 +0000[diff] [blame]4592<!-- _______________________________________________________________________ -->
4593<div class="doc_subsubsection">
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4594 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4595</div>
4596
4597<div class="doc_text">
4598
4599<h5>Syntax:</h5>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4600<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4601on any integer bit width.
4602<pre>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4603 declare i17 @llvm.part.select.i17.i17 (i17 %val, i32 %loBit, i32 %hiBit)
4604 declare i29 @llvm.part.select.i29.i29 (i29 %val, i32 %loBit, i32 %hiBit)
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4605</pre>
4606
4607<h5>Overview:</h5>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4608<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4609range of bits from an integer value and returns them in the same bit width as
4610the original value.</p>
4611
4612<h5>Arguments:</h5>
4613<p>The first argument, <tt>%val</tt> and the result may be integer types of
4614any bit width but they must have the same bit width. The second and third
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4615arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4616
4617<h5>Semantics:</h5>
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4618<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4619of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
4620<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
4621operates in forward mode.</p>
4622<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
4623right by <tt>%loBit</tt> bits and then ANDing it with a mask with
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4624only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
4625<ol>
4626 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
4627 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
4628 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
4629 to determine the number of bits to retain.</li>
4630 <li>A mask of the retained bits is created by shifting a -1 value.</li>
4631 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
4632</ol>
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4633<p>In reverse mode, a similar computation is made except that:</p>
4634<ol>
4635 <li>The bits selected wrap around to include both the highest and lowest bits.
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4636 For example, part.select(i16 X, 4, 7) selects bits from X with a mask of
4637 0x00F0 (forwards case) while part.select(i16 X, 8, 3) selects bits from X
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4638 with a mask of 0xFF0F.</li>
4639 <li>The bits returned in the reverse case are reversed. So, if X has the value
Reid Spencerea2945e2007-04-10 02:51:31 +0000[diff] [blame]4640 0x6ACF and we apply part.select(i16 X, 8, 3) to it, we get back the value
Reid Spencer96a5f022007-04-04 02:42:35 +0000[diff] [blame]4641 0x0A6F.</li>
4642</ol>
Reid Spencer8bc7d952007-04-01 19:00:37 +0000[diff] [blame]4643</div>
4644
Reid Spencer5bf54c82007-04-11 23:23:49 +0000[diff] [blame^]4645<div class="doc_subsubsection">
4646 <a name="int_part_set">'<tt>llvm.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.part.set</tt>
4653on any integer bit width.
4654<pre>
4655 declare i17 @llvm.part.set.i17.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
4656 declare i29 @llvm.part.set.i29.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
4657</pre>
4658
4659<h5>Overview:</h5>
4660<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
4661of bits in an integer value with another integer value. It returns the integer
4662with the replaced bits.</p>
4663
4664<h5>Arguments:</h5>
4665<p>The first argument, <tt>%val</tt> and the result may be integer types of
4666any bit width but they must have the same bit width. <tt>%val</tt> is the value
4667whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
4668integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
4669type since they specify only a bit index.</p>
4670
4671<h5>Semantics:</h5>
4672<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
4673of operation: forwards and reverse. If <tt>%lo</tt> is greater than
4674<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
4675operates in forward mode.</p>
4676<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
4677truncating it down to the size of the replacement area or zero extending it
4678up to that size.</p>
4679<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
4680are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
4681in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
4682to the <tt>%hi</tt>th bit.
4683<p>In reverse mode, a similar computation is made except that the bits replaced
4684wrap around to include both the highest and lowest bits. For example, if a
468516 bit value is being replaced then <tt>%lo=8</tt> and <tt>%hi=4</tt> would
4686cause these bits to be set: <tt>0xFF1F</p>.
4687<h5>Examples:</h5>
4688<pre>
4689 llvm.part.set(0xFFFF, 0, Y, 4, 7) -&gt; 0xFF0F
4690 llvm.part.set(0xFFFF, 0, Y, 7, 4) -&gt; 0x0060
4691 llvm.part.set(0xFFFF, 0, Y, 8, 3) -&gt; 0x00F0
4692 llvm.part.set(0xFFFF, 0, Y, 3, 8) -&gt; 0xFE07
4693</div>
4694
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4695<!-- ======================================================================= -->
4696<div class="doc_subsection">
4697 <a name="int_debugger">Debugger Intrinsics</a>
4698</div>
4699
4700<div class="doc_text">
4701<p>
4702The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4703are described in the <a
4704href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4705Debugging</a> document.
4706</p>
4707</div>
4708
4709
Jim Laskey2211f492007-03-14 19:31:19 +0000[diff] [blame]4710<!-- ======================================================================= -->
4711<div class="doc_subsection">
4712 <a name="int_eh">Exception Handling Intrinsics</a>
4713</div>
4714
4715<div class="doc_text">
4716<p> The LLVM exception handling intrinsics (which all start with
4717<tt>llvm.eh.</tt> prefix), are described in the <a
4718href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
4719Handling</a> document. </p>
4720</div>
4721
4722
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4723<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4724<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4725<address>
4726 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4727 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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4729 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4730
4731 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +0000[diff] [blame]4732 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4733 Last modified: $Date$
4734</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]4735</body>
4736</html>