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gerrit-public.fairphone.software / toolchain / llvm-project / c7f9f3df24a050a34537871daed7985c08fb293e / . / 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>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]29 </ol>
30 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]31 <li><a href="#typesystem">Type System</a>
32 <ol>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]33 <li><a href="#t_primitive">Primitive Types</a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]34 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]35 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]36 </ol>
37 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]38 <li><a href="#t_derived">Derived Types</a>
39 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]40 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]41 <li><a href="#t_function">Function Type</a></li>
42 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]43 <li><a href="#t_struct">Structure Type</a></li>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]44 <li><a href="#t_pstruct">Packed Structure Type</a></li>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]45 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]46 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]47 </ol>
48 </li>
49 </ol>
50 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]51 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]52 <ol>
53 <li><a href="#simpleconstants">Simple Constants</a>
54 <li><a href="#aggregateconstants">Aggregate Constants</a>
55 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
56 <li><a href="#undefvalues">Undefined Values</a>
57 <li><a href="#constantexprs">Constant Expressions</a>
58 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]59 </li>
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]60 <li><a href="#othervalues">Other Values</a>
61 <ol>
62 <li><a href="#inlineasm">Inline Assembler Expressions</a>
63 </ol>
64 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]65 <li><a href="#instref">Instruction Reference</a>
66 <ol>
67 <li><a href="#terminators">Terminator Instructions</a>
68 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]69 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
70 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]71 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
72 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]73 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]74 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]75 </ol>
76 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]77 <li><a href="#binaryops">Binary Operations</a>
78 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]79 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
80 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
81 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]82 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
83 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
84 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]85 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
86 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
87 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]88 </ol>
89 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]90 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
91 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]92 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]93 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]94 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
95 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]96 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
97 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]98 </ol>
99 </li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]100 <li><a href="#vectorops">Vector Operations</a>
101 <ol>
102 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
103 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
104 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]105 </ol>
106 </li>
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]107 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]108 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]109 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
110 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
111 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]112 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
113 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
114 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]115 </ol>
116 </li>
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]117 <li><a href="#convertops">Conversion Operations</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]118 <ol>
119 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
120 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
121 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
122 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
123 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]124 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
125 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
126 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
127 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]128 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
129 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]130 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]131 </ol>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]132 <li><a href="#otherops">Other Operations</a>
133 <ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]134 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
135 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]136 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]137 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]138 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]139 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]140 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]141 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]142 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]143 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]144 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]145 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]146 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
147 <ol>
148 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
149 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
150 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
151 </ol>
152 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]153 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
154 <ol>
155 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
156 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
157 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
158 </ol>
159 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]160 <li><a href="#int_codegen">Code Generator Intrinsics</a>
161 <ol>
162 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
163 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]164 <li><a href="#i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
165 <li><a href="#i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]166 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]167 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]168 <li><a href="#i_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]169 </ol>
170 </li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]171 <li><a href="#int_libc">Standard C Library Intrinsics</a>
172 <ol>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]173 <li><a href="#i_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
174 <li><a href="#i_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
175 <li><a href="#i_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]176 <li><a href="#i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]177 <li><a href="#i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]178 </ol>
179 </li>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]180 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]181 <ol>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]182 <li><a href="#i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]183 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
184 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
185 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]186 </ol>
187 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]188 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]189 </ol>
190 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]191</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]192
193<div class="doc_author">
194 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
195 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]196</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]197
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]198<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]199<div class="doc_section"> <a name="abstract">Abstract </a></div>
200<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]201
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]202<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]203<p>This document is a reference manual for the LLVM assembly language.
204LLVM is an SSA based representation that provides type safety,
205low-level operations, flexibility, and the capability of representing
206'all' high-level languages cleanly. It is the common code
207representation used throughout all phases of the LLVM compilation
208strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]209</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]210
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]211<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]212<div class="doc_section"> <a name="introduction">Introduction</a> </div>
213<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]214
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]215<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]216
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]217<p>The LLVM code representation is designed to be used in three
218different forms: as an in-memory compiler IR, as an on-disk bytecode
219representation (suitable for fast loading by a Just-In-Time compiler),
220and as a human readable assembly language representation. This allows
221LLVM to provide a powerful intermediate representation for efficient
222compiler transformations and analysis, while providing a natural means
223to debug and visualize the transformations. The three different forms
224of LLVM are all equivalent. This document describes the human readable
225representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]226
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]227<p>The LLVM representation aims to be light-weight and low-level
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]228while being expressive, typed, and extensible at the same time. It
229aims to be a "universal IR" of sorts, by being at a low enough level
230that high-level ideas may be cleanly mapped to it (similar to how
231microprocessors are "universal IR's", allowing many source languages to
232be mapped to them). By providing type information, LLVM can be used as
233the target of optimizations: for example, through pointer analysis, it
234can be proven that a C automatic variable is never accessed outside of
235the current function... allowing it to be promoted to a simple SSA
236value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]237
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]238</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]239
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]240<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]241<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]242
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]243<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]244
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]245<p>It is important to note that this document describes 'well formed'
246LLVM assembly language. There is a difference between what the parser
247accepts and what is considered 'well formed'. For example, the
248following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]249
250<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]251 %x = <a href="#i_add">add</a> i32 1, %x
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]252</pre>
253
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]254<p>...because the definition of <tt>%x</tt> does not dominate all of
255its uses. The LLVM infrastructure provides a verification pass that may
256be used to verify that an LLVM module is well formed. This pass is
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]257automatically run by the parser after parsing input assembly and by
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]258the optimizer before it outputs bytecode. The violations pointed out
259by the verifier pass indicate bugs in transformation passes or input to
260the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]261
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]262<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]263
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]264<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]265<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]266<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]267
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]268<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]269
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]270<p>LLVM uses three different forms of identifiers, for different
271purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]272
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]273<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]274 <li>Named values are represented as a string of characters with a '%' prefix.
275 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
276 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
277 Identifiers which require other characters in their names can be surrounded
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]278 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]279 in a name.</li>
280
281 <li>Unnamed values are represented as an unsigned numeric value with a '%'
282 prefix. For example, %12, %2, %44.</li>
283
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]284 <li>Constants, which are described in a <a href="#constants">section about
285 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]286</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]287
288<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
289don't need to worry about name clashes with reserved words, and the set of
290reserved words may be expanded in the future without penalty. Additionally,
291unnamed identifiers allow a compiler to quickly come up with a temporary
292variable without having to avoid symbol table conflicts.</p>
293
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]294<p>Reserved words in LLVM are very similar to reserved words in other
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]295languages. There are keywords for different opcodes
296('<tt><a href="#i_add">add</a></tt>',
297 '<tt><a href="#i_bitcast">bitcast</a></tt>',
298 '<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]299href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]300and others. These reserved words cannot conflict with variable names, because
301none of them start with a '%' character.</p>
302
303<p>Here is an example of LLVM code to multiply the integer variable
304'<tt>%X</tt>' by 8:</p>
305
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]306<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]307
308<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]309 %result = <a href="#i_mul">mul</a> i32 %X, 8
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]310</pre>
311
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]312<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]313
314<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]315 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]316</pre>
317
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]318<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]319
320<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]321 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
322 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
323 %result = <a href="#i_add">add</a> i32 %1, %1
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]324</pre>
325
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]326<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
327important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]328
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]329<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]330
331 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
332 line.</li>
333
334 <li>Unnamed temporaries are created when the result of a computation is not
335 assigned to a named value.</li>
336
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]337 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]338
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]339</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]340
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]341<p>...and it also shows a convention that we follow in this document. When
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]342demonstrating instructions, we will follow an instruction with a comment that
343defines the type and name of value produced. Comments are shown in italic
344text.</p>
345
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]346</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]347
348<!-- *********************************************************************** -->
349<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
350<!-- *********************************************************************** -->
351
352<!-- ======================================================================= -->
353<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
354</div>
355
356<div class="doc_text">
357
358<p>LLVM programs are composed of "Module"s, each of which is a
359translation unit of the input programs. Each module consists of
360functions, global variables, and symbol table entries. Modules may be
361combined together with the LLVM linker, which merges function (and
362global variable) definitions, resolves forward declarations, and merges
363symbol table entries. Here is an example of the "hello world" module:</p>
364
365<pre><i>; Declare the string constant as a global constant...</i>
366<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]367 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]368
369<i>; External declaration of the puts function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]370<a href="#functionstructure">declare</a> i32 %puts(i8 *) <i>; i32(i8 *)* </i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]371
Chris Lattnerd2d29a02006-06-13 03:05:47 +0000[diff] [blame]372<i>; Global variable / Function body section separator</i>
373implementation
374
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]375<i>; Definition of main function</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]376define i32 %main() { <i>; i32()* </i>
377 <i>; Convert [13x i8 ]* to i8 *...</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]378 %cast210 = <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]379 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* %.LC0, i64 0, i64 0 <i>; i8 *</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]380
381 <i>; Call puts function to write out the string to stdout...</i>
382 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]383 href="#i_call">call</a> i32 %puts(i8 * %cast210) <i>; i32</i>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]384 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]385 href="#i_ret">ret</a> i32 0<br>}<br></pre>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]386
387<p>This example is made up of a <a href="#globalvars">global variable</a>
388named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
389function, and a <a href="#functionstructure">function definition</a>
390for "<tt>main</tt>".</p>
391
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]392<p>In general, a module is made up of a list of global values,
393where both functions and global variables are global values. Global values are
394represented by a pointer to a memory location (in this case, a pointer to an
395array of char, and a pointer to a function), and have one of the following <a
396href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]397
Chris Lattnerd2d29a02006-06-13 03:05:47 +0000[diff] [blame]398<p>Due to a limitation in the current LLVM assembly parser (it is limited by
399one-token lookahead), modules are split into two pieces by the "implementation"
400keyword. Global variable prototypes and definitions must occur before the
401keyword, and function definitions must occur after it. Function prototypes may
402occur either before or after it. In the future, the implementation keyword may
403become a noop, if the parser gets smarter.</p>
404
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]405</div>
406
407<!-- ======================================================================= -->
408<div class="doc_subsection">
409 <a name="linkage">Linkage Types</a>
410</div>
411
412<div class="doc_text">
413
414<p>
415All Global Variables and Functions have one of the following types of linkage:
416</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]417
418<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]419
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]420 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]421
422 <dd>Global values with internal linkage are only directly accessible by
423 objects in the current module. In particular, linking code into a module with
424 an internal global value may cause the internal to be renamed as necessary to
425 avoid collisions. Because the symbol is internal to the module, all
426 references can be updated. This corresponds to the notion of the
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]427 '<tt>static</tt>' keyword in C.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]428 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]429
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]430 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]431
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]432 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
433 the same name when linkage occurs. This is typically used to implement
434 inline functions, templates, or other code which must be generated in each
435 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
436 allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]437 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]438
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]439 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]440
441 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
442 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
Chris Lattnere20b4702007-01-14 06:51:48 +0000[diff] [blame]443 used for globals that may be emitted in multiple translation units, but that
444 are not guaranteed to be emitted into every translation unit that uses them.
445 One example of this are common globals in C, such as "<tt>int X;</tt>" at
446 global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]447 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]448
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]449 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]450
451 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
452 pointer to array type. When two global variables with appending linkage are
453 linked together, the two global arrays are appended together. This is the
454 LLVM, typesafe, equivalent of having the system linker append together
455 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]456 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]457
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]458 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
459 <dd>The semantics of this linkage follow the ELF model: the symbol is weak
460 until linked, if not linked, the symbol becomes null instead of being an
461 undefined reference.
462 </dd>
463</dl>
464
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]465 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]466
467 <dd>If none of the above identifiers are used, the global is externally
468 visible, meaning that it participates in linkage and can be used to resolve
469 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]470 </dd>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]471
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]472 <p>
473 The next two types of linkage are targeted for Microsoft Windows platform
474 only. They are designed to support importing (exporting) symbols from (to)
475 DLLs.
476 </p>
477
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]478 <dl>
Anton Korobeynikovd61d39e2006-09-14 18:23:27 +0000[diff] [blame]479 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
480
481 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
482 or variable via a global pointer to a pointer that is set up by the DLL
483 exporting the symbol. On Microsoft Windows targets, the pointer name is
484 formed by combining <code>_imp__</code> and the function or variable name.
485 </dd>
486
487 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
488
489 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
490 pointer to a pointer in a DLL, so that it can be referenced with the
491 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
492 name is formed by combining <code>_imp__</code> and the function or variable
493 name.
494 </dd>
495
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]496</dl>
497
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]498<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]499variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
500variable and was linked with this one, one of the two would be renamed,
501preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
502external (i.e., lacking any linkage declarations), they are accessible
Reid Spencer92c671e2007-01-05 00:59:10 +0000[diff] [blame]503outside of the current module.</p>
504<p>It is illegal for a function <i>declaration</i>
505to have any linkage type other than "externally visible", <tt>dllimport</tt>,
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]506or <tt>extern_weak</tt>.</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]507
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]508</div>
509
510<!-- ======================================================================= -->
511<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]512 <a name="callingconv">Calling Conventions</a>
513</div>
514
515<div class="doc_text">
516
517<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
518and <a href="#i_invoke">invokes</a> can all have an optional calling convention
519specified for the call. The calling convention of any pair of dynamic
520caller/callee must match, or the behavior of the program is undefined. The
521following calling conventions are supported by LLVM, and more may be added in
522the future:</p>
523
524<dl>
525 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
526
527 <dd>This calling convention (the default if no other calling convention is
528 specified) matches the target C calling conventions. This calling convention
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]529 supports varargs function calls and tolerates some mismatch in the declared
Reid Spencer72ba4992006-12-31 21:30:18 +0000[diff] [blame]530 prototype and implemented declaration of the function (as does normal C).
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]531 </dd>
532
Chris Lattner95ff1952006-05-19 21:15:36 +0000[diff] [blame]533 <dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
534
535 <dd>This calling convention matches the target C calling conventions, except
536 that functions with this convention are required to take a pointer as their
537 first argument, and the return type of the function must be void. This is
538 used for C functions that return aggregates by-value. In this case, the
539 function has been transformed to take a pointer to the struct as the first
540 argument to the function. For targets where the ABI specifies specific
541 behavior for structure-return calls, the calling convention can be used to
542 distinguish between struct return functions and other functions that take a
543 pointer to a struct as the first argument.
544 </dd>
545
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]546 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
547
548 <dd>This calling convention attempts to make calls as fast as possible
549 (e.g. by passing things in registers). This calling convention allows the
550 target to use whatever tricks it wants to produce fast code for the target,
Chris Lattnerc792eb32005-05-06 23:08:23 +0000[diff] [blame]551 without having to conform to an externally specified ABI. Implementations of
552 this convention should allow arbitrary tail call optimization to be supported.
553 This calling convention does not support varargs and requires the prototype of
554 all callees to exactly match the prototype of the function definition.
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]555 </dd>
556
557 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
558
559 <dd>This calling convention attempts to make code in the caller as efficient
560 as possible under the assumption that the call is not commonly executed. As
561 such, these calls often preserve all registers so that the call does not break
562 any live ranges in the caller side. This calling convention does not support
563 varargs and requires the prototype of all callees to exactly match the
564 prototype of the function definition.
565 </dd>
566
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]567 <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]568
569 <dd>Any calling convention may be specified by number, allowing
570 target-specific calling conventions to be used. Target specific calling
571 conventions start at 64.
572 </dd>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]573</dl>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]574
575<p>More calling conventions can be added/defined on an as-needed basis, to
576support pascal conventions or any other well-known target-independent
577convention.</p>
578
579</div>
580
581<!-- ======================================================================= -->
582<div class="doc_subsection">
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame^]583 <a name="visibility">Visibility Styles</a>
584</div>
585
586<div class="doc_text">
587
588<p>
589All Global Variables and Functions have one of the following visibility styles:
590</p>
591
592<dl>
593 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
594
595 <dd>On ELF, default visibility means that the declaration is visible to other
596 modules and, in shared libraries, means that the declared entity may be
597 overridden. On Darwin, default visibility means that the declaration is
598 visible to other modules. Default visibility corresponds to "external
599 linkage" in the language.
600 </dd>
601
602 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
603
604 <dd>Two declarations of an object with hidden visibility refer to the same
605 object if they are in the same shared object. Usually, hidden visibility
606 indicates that the symbol will not be placed into the dynamic symbol table,
607 so no other module (executable or shared library) can reference it
608 directly.
609 </dd>
610
611</dl>
612
613</div>
614
615<!-- ======================================================================= -->
616<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]617 <a name="globalvars">Global Variables</a>
618</div>
619
620<div class="doc_text">
621
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]622<p>Global variables define regions of memory allocated at compilation time
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]623instead of run-time. Global variables may optionally be initialized, may have
624an explicit section to be placed in, and may
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]625have an optional explicit alignment specified. A
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]626variable may be defined as a global "constant," which indicates that the
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]627contents of the variable will <b>never</b> be modified (enabling better
628optimization, allowing the global data to be placed in the read-only section of
629an executable, etc). Note that variables that need runtime initialization
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]630cannot be marked "constant" as there is a store to the variable.</p>
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]631
632<p>
633LLVM explicitly allows <em>declarations</em> of global variables to be marked
634constant, even if the final definition of the global is not. This capability
635can be used to enable slightly better optimization of the program, but requires
636the language definition to guarantee that optimizations based on the
637'constantness' are valid for the translation units that do not include the
638definition.
639</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]640
641<p>As SSA values, global variables define pointer values that are in
642scope (i.e. they dominate) all basic blocks in the program. Global
643variables always define a pointer to their "content" type because they
644describe a region of memory, and all memory objects in LLVM are
645accessed through pointers.</p>
646
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]647<p>LLVM allows an explicit section to be specified for globals. If the target
648supports it, it will emit globals to the section specified.</p>
649
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]650<p>An explicit alignment may be specified for a global. If not present, or if
651the alignment is set to zero, the alignment of the global is set by the target
652to whatever it feels convenient. If an explicit alignment is specified, the
653global is forced to have at least that much alignment. All alignments must be
654a power of 2.</p>
655
Chris Lattner5760c502007-01-14 00:27:09 +0000[diff] [blame]656<p>For example, the following defines a global with an initializer, section,
657 and alignment:</p>
658
659<pre>
660 %G = constant float 1.0, section "foo", align 4
661</pre>
662
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]663</div>
664
665
666<!-- ======================================================================= -->
667<div class="doc_subsection">
668 <a name="functionstructure">Functions</a>
669</div>
670
671<div class="doc_text">
672
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]673<p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
674an optional <a href="#linkage">linkage type</a>, an optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame^]675<a href="#visibility">visibility style</a>, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]676<a href="#callingconv">calling convention</a>, a return type, an optional
677<a href="#paramattrs">parameter attribute</a> for the return type, a function
678name, a (possibly empty) argument list (each with optional
Anton Korobeynikovc7f9f3d2007-01-23 12:35:46 +0000[diff] [blame^]679<a href="#paramattrs">parameter attributes</a>), an optional section, an
680optional alignment, an opening curly brace, a list of basic blocks, and a
681closing curly brace.
682
683LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
684optional <a href="#linkage">linkage type</a>, an optional
685<a href="#visibility">visibility style</a>, an optional
686<a href="#callingconv">calling convention</a>, a return type, an optional
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]687<a href="#paramattrs">parameter attribute</a> for the return type, a function
688name, a possibly empty list of arguments, and an optional alignment.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]689
690<p>A function definition contains a list of basic blocks, forming the CFG for
691the function. Each basic block may optionally start with a label (giving the
692basic block a symbol table entry), contains a list of instructions, and ends
693with a <a href="#terminators">terminator</a> instruction (such as a branch or
694function return).</p>
695
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]696<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]697executed on entrance to the function, and it is not allowed to have predecessor
698basic blocks (i.e. there can not be any branches to the entry block of a
699function). Because the block can have no predecessors, it also cannot have any
700<a href="#i_phi">PHI nodes</a>.</p>
701
702<p>LLVM functions are identified by their name and type signature. Hence, two
703functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]704considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]705appropriately.</p>
706
Chris Lattner662c8722005-11-12 00:45:07 +0000[diff] [blame]707<p>LLVM allows an explicit section to be specified for functions. If the target
708supports it, it will emit functions to the section specified.</p>
709
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]710<p>An explicit alignment may be specified for a function. If not present, or if
711the alignment is set to zero, the alignment of the function is set by the target
712to whatever it feels convenient. If an explicit alignment is specified, the
713function is forced to have at least that much alignment. All alignments must be
714a power of 2.</p>
715
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]716</div>
717
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]718<!-- ======================================================================= -->
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]719<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
720<div class="doc_text">
721 <p>The return type and each parameter of a function type may have a set of
722 <i>parameter attributes</i> associated with them. Parameter attributes are
723 used to communicate additional information about the result or parameters of
724 a function. Parameter attributes are considered to be part of the function
725 type so two functions types that differ only by the parameter attributes
726 are different function types.</p>
727
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]728 <p>Parameter attributes are simple keywords that follow the type specified. If
729 multiple parameter attributes are needed, they are space separated. For
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]730 example:</p><pre>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]731 %someFunc = i16 (i8 sext %someParam) zext
732 %someFunc = i16 (i8 zext %someParam) zext</pre>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]733 <p>Note that the two function types above are unique because the parameter has
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]734 a different attribute (sext in the first one, zext in the second). Also note
735 that the attribute for the function result (zext) comes immediately after the
736 argument list.</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]737
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]738 <p>Currently, only the following parameter attributes are defined:</p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]739 <dl>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]740 <dt><tt>zext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]741 <dd>This indicates that the parameter should be zero extended just before
742 a call to this function.</dd>
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]743 <dt><tt>sext</tt></dt>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]744 <dd>This indicates that the parameter should be sign extended just before
745 a call to this function.</dd>
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]746 </dl>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]747
748 <p>The current motivation for parameter attributes is to enable the sign and
749 zero extend information necessary for the C calling convention to be passed
Reid Spencercf7ebf52007-01-15 18:27:39 +0000[diff] [blame]750 from the front end to LLVM. The <tt>zext</tt> and <tt>sext</tt> attributes
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]751 are used by the code generator to perform the required extension. However,
752 parameter attributes are an orthogonal feature to calling conventions and
753 may be used for other purposes in the future.</p>
754</div>
755
756<!-- ======================================================================= -->
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]757<div class="doc_subsection">
Chris Lattner93564892006-04-08 04:40:53 +0000[diff] [blame]758 <a name="moduleasm">Module-Level Inline Assembly</a>
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]759</div>
760
761<div class="doc_text">
762<p>
763Modules may contain "module-level inline asm" blocks, which corresponds to the
764GCC "file scope inline asm" blocks. These blocks are internally concatenated by
765LLVM and treated as a single unit, but may be separated in the .ll file if
766desired. The syntax is very simple:
767</p>
768
769<div class="doc_code"><pre>
Chris Lattnera1280ad2006-01-24 00:37:20 +0000[diff] [blame]770 module asm "inline asm code goes here"
771 module asm "more can go here"
Chris Lattner91c15c42006-01-23 23:23:47 +0000[diff] [blame]772</pre></div>
773
774<p>The strings can contain any character by escaping non-printable characters.
775 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
776 for the number.
777</p>
778
779<p>
780 The inline asm code is simply printed to the machine code .s file when
781 assembly code is generated.
782</p>
783</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]784
785
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]786<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]787<div class="doc_section"> <a name="typesystem">Type System</a> </div>
788<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]789
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]790<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]791
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]792<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]793intermediate representation. Being typed enables a number of
794optimizations to be performed on the IR directly, without having to do
795extra analyses on the side before the transformation. A strong type
796system makes it easier to read the generated code and enables novel
797analyses and transformations that are not feasible to perform on normal
798three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]799
800</div>
801
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]802<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]803<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]804<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]805<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]806system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]807
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]808<table class="layout">
809 <tr class="layout">
810 <td class="left">
811 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]812 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]813 <tr><th>Type</th><th>Description</th></tr>
814 <tr><td><tt>void</tt></td><td>No value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]815 <tr><td><tt>i8</tt></td><td>8-bit value</td></tr>
816 <tr><td><tt>i32</tt></td><td>32-bit value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]817 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]818 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]819 </tbody>
820 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]821 </td>
822 <td class="right">
823 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]824 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]825 <tr><th>Type</th><th>Description</th></tr>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]826 <tr><td><tt>i1</tt></td><td>True or False value</td></tr>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]827 <tr><td><tt>i16</tt></td><td>16-bit value</td></tr>
828 <tr><td><tt>i64</tt></td><td>64-bit value</td></tr>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]829 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]830 </tbody>
831 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]832 </td>
833 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]834</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]835</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]836
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]837<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]838<div class="doc_subsubsection"> <a name="t_classifications">Type
839Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]840<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]841<p>These different primitive types fall into a few useful
842classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]843
844<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]845 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]846 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]847 <tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]848 <td><a name="t_integer">integer</a></td>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]849 <td><tt>i1, i8, i16, i32, i64</tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]850 </tr>
851 <tr>
852 <td><a name="t_floating">floating point</a></td>
853 <td><tt>float, double</tt></td>
854 </tr>
855 <tr>
856 <td><a name="t_firstclass">first class</a></td>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]857 <td><tt>i1, i8, i16, i32, i64, float, double, <br/>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]858 <a href="#t_pointer">pointer</a>,<a href="#t_packed">packed</a></tt>
859 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]860 </tr>
861 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]862</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]863
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]864<p>The <a href="#t_firstclass">first class</a> types are perhaps the
865most important. Values of these types are the only ones which can be
866produced by instructions, passed as arguments, or used as operands to
867instructions. This means that all structures and arrays must be
868manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]869</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]870
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]871<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]872<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]873
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]874<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]875
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]876<p>The real power in LLVM comes from the derived types in the system.
877This is what allows a programmer to represent arrays, functions,
878pointers, and other useful types. Note that these derived types may be
879recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]880
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]881</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]882
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]883<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]884<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]885
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]886<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]887
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]888<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]889
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]890<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]891sequentially in memory. The array type requires a size (number of
892elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]893
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]894<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]895
896<pre>
897 [&lt;# elements&gt; x &lt;elementtype&gt;]
898</pre>
899
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]900<p>The number of elements is a constant integer value; elementtype may
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]901be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]902
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]903<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]904<table class="layout">
905 <tr class="layout">
906 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]907 <tt>[40 x i32 ]</tt><br/>
908 <tt>[41 x i32 ]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]909 <tt>[40 x i8]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]910 </td>
911 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]912 Array of 40 32-bit integer values.<br/>
913 Array of 41 32-bit integer values.<br/>
914 Array of 40 8-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]915 </td>
916 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]917</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]918<p>Here are some examples of multidimensional arrays:</p>
919<table class="layout">
920 <tr class="layout">
921 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]922 <tt>[3 x [4 x i32]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]923 <tt>[12 x [10 x float]]</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]924 <tt>[2 x [3 x [4 x i16]]]</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]925 </td>
926 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]927 3x4 array of 32-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]928 12x10 array of single precision floating point values.<br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]929 2x3x4 array of 16-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]930 </td>
931 </tr>
932</table>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]933
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]934<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
935length array. Normally, accesses past the end of an array are undefined in
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]936LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
937As a special case, however, zero length arrays are recognized to be variable
938length. This allows implementation of 'pascal style arrays' with the LLVM
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]939type "{ i32, [0 x float]}", for example.</p>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]940
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]941</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]942
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]943<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]944<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]945<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]946<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]947<p>The function type can be thought of as a function signature. It
948consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]949Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]950(which are structures of pointers to functions), for indirect function
951calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]952<p>
953The return type of a function type cannot be an aggregate type.
954</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]955<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]956<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]957<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]958specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]959which indicates that the function takes a variable number of arguments.
960Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]961 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]962<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]963<table class="layout">
964 <tr class="layout">
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]965 <td class="left"><tt>i32 (i32)</tt></td>
966 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]967 </td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]968 </tr><tr class="layout">
Reid Spencere6a338d2007-01-15 18:28:34 +0000[diff] [blame]969 <td class="left"><tt>float&nbsp;(i16&nbsp;sext,&nbsp;i32&nbsp;*)&nbsp;*
Reid Spencer655dcc62006-12-31 07:20:23 +0000[diff] [blame]970 </tt></td>
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]971 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
972 an <tt>i16</tt> that should be sign extended and a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]973 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]974 <tt>float</tt>.
975 </td>
976 </tr><tr class="layout">
977 <td class="left"><tt>i32 (i8*, ...)</tt></td>
978 <td class="left">A vararg function that takes at least one
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]979 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
Reid Spencer58c08712006-12-31 07:18:34 +0000[diff] [blame]980 which returns an integer. This is the signature for <tt>printf</tt> in
981 LLVM.
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]982 </td>
983 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]984</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]985
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]986</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]987<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]988<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]989<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]990<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]991<p>The structure type is used to represent a collection of data members
992together in memory. The packing of the field types is defined to match
993the ABI of the underlying processor. The elements of a structure may
994be any type that has a size.</p>
995<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
996and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
997field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
998instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]999<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1000<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1001<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1002<table class="layout">
1003 <tr class="layout">
1004 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1005 <tt>{ i32, i32, i32 }</tt><br/>
1006 <tt>{ float, i32 (i32) * }</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1007 </td>
1008 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1009 a triple of three <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1010 A pair, where the first element is a <tt>float</tt> and the second element
1011 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]1012 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1013 </td>
1014 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1015</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1016</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1017
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1018<!-- _______________________________________________________________________ -->
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1019<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1020</div>
1021<div class="doc_text">
1022<h5>Overview:</h5>
1023<p>The packed structure type is used to represent a collection of data members
1024together in memory. There is no padding between fields. Further, the alignment
1025of a packed structure is 1 byte. The elements of a packed structure may
1026be any type that has a size.</p>
1027<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1028and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1029field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1030instruction.</p>
1031<h5>Syntax:</h5>
1032<pre> &lt; { &lt;type list&gt; } &gt; <br></pre>
1033<h5>Examples:</h5>
1034<table class="layout">
1035 <tr class="layout">
1036 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1037 <tt> &lt; { i32, i32, i32 } &gt; </tt><br/>
1038 <tt> &lt; { float, i32 (i32) * } &gt; </tt><br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1039 </td>
1040 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1041 a triple of three <tt>i32</tt> values<br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1042 A pair, where the first element is a <tt>float</tt> and the second element
1043 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]1044 that takes an <tt>i32</tt>, returning an <tt>i32</tt>.<br/>
Andrew Lenharth8df88e22006-12-08 17:13:00 +0000[diff] [blame]1045 </td>
1046 </tr>
1047</table>
1048</div>
1049
1050<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1051<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1052<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1053<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1054<p>As in many languages, the pointer type represents a pointer or
1055reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1056<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1057<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1058<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1059<table class="layout">
1060 <tr class="layout">
1061 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1062 <tt>[4x i32]*</tt><br/>
1063 <tt>i32 (i32 *) *</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1064 </td>
1065 <td class="left">
1066 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]1067 four <tt>i32</tt> values<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1068 A <a href="#t_pointer">pointer</a> to a <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1069 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1070 <tt>i32</tt>.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1071 </td>
1072 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1073</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1074</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1075
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1076<!-- _______________________________________________________________________ -->
1077<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1078<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1079
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1080<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1081
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1082<p>A packed type is a simple derived type that represents a vector
1083of elements. Packed types are used when multiple primitive data
1084are operated in parallel using a single instruction (SIMD).
1085A packed type requires a size (number of
Chris Lattner330ce692005-11-10 01:44:22 +0000[diff] [blame]1086elements) and an underlying primitive data type. Vectors must have a power
1087of two length (1, 2, 4, 8, 16 ...). Packed types are
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1088considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1089
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1090<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1091
1092<pre>
1093 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
1094</pre>
1095
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1096<p>The number of elements is a constant integer value; elementtype may
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1097be any integer or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1098
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1099<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1100
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1101<table class="layout">
1102 <tr class="layout">
1103 <td class="left">
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1104 <tt>&lt;4 x i32&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1105 <tt>&lt;8 x float&gt;</tt><br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1106 <tt>&lt;2 x i64&gt;</tt><br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1107 </td>
1108 <td class="left">
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1109 Packed vector of 4 32-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1110 Packed vector of 8 floating-point values.<br/>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1111 Packed vector of 2 64-bit integer values.<br/>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]1112 </td>
1113 </tr>
1114</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1115</div>
1116
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]1117<!-- _______________________________________________________________________ -->
1118<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1119<div class="doc_text">
1120
1121<h5>Overview:</h5>
1122
1123<p>Opaque types are used to represent unknown types in the system. This
1124corresponds (for example) to the C notion of a foward declared structure type.
1125In LLVM, opaque types can eventually be resolved to any type (not just a
1126structure type).</p>
1127
1128<h5>Syntax:</h5>
1129
1130<pre>
1131 opaque
1132</pre>
1133
1134<h5>Examples:</h5>
1135
1136<table class="layout">
1137 <tr class="layout">
1138 <td class="left">
1139 <tt>opaque</tt>
1140 </td>
1141 <td class="left">
1142 An opaque type.<br/>
1143 </td>
1144 </tr>
1145</table>
1146</div>
1147
1148
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1149<!-- *********************************************************************** -->
1150<div class="doc_section"> <a name="constants">Constants</a> </div>
1151<!-- *********************************************************************** -->
1152
1153<div class="doc_text">
1154
1155<p>LLVM has several different basic types of constants. This section describes
1156them all and their syntax.</p>
1157
1158</div>
1159
1160<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1161<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1162
1163<div class="doc_text">
1164
1165<dl>
1166 <dt><b>Boolean constants</b></dt>
1167
1168 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1169 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1170 </dd>
1171
1172 <dt><b>Integer constants</b></dt>
1173
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1174 <dd>Standard integers (such as '4') are constants of the <a
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1175 href="#t_integer">integer</a> type. Negative numbers may be used with
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1176 integer types.
1177 </dd>
1178
1179 <dt><b>Floating point constants</b></dt>
1180
1181 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1182 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1183 notation (see below). Floating point constants must have a <a
1184 href="#t_floating">floating point</a> type. </dd>
1185
1186 <dt><b>Null pointer constants</b></dt>
1187
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1188 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1189 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1190
1191</dl>
1192
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1193<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1194of floating point constants. For example, the form '<tt>double
11950x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
11964.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]1197(and the only time that they are generated by the disassembler) is when a
1198floating point constant must be emitted but it cannot be represented as a
1199decimal floating point number. For example, NaN's, infinities, and other
1200special values are represented in their IEEE hexadecimal format so that
1201assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1202
1203</div>
1204
1205<!-- ======================================================================= -->
1206<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1207</div>
1208
1209<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1210<p>Aggregate constants arise from aggregation of simple constants
1211and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1212
1213<dl>
1214 <dt><b>Structure constants</b></dt>
1215
1216 <dd>Structure constants are represented with notation similar to structure
1217 type definitions (a comma separated list of elements, surrounded by braces
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1218 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
1219 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]1220 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1221 types of elements must match those specified by the type.
1222 </dd>
1223
1224 <dt><b>Array constants</b></dt>
1225
1226 <dd>Array constants are represented with notation similar to array type
1227 definitions (a comma separated list of elements, surrounded by square brackets
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1228 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1229 constants must have <a href="#t_array">array type</a>, and the number and
1230 types of elements must match those specified by the type.
1231 </dd>
1232
1233 <dt><b>Packed constants</b></dt>
1234
1235 <dd>Packed constants are represented with notation similar to packed type
1236 definitions (a comma separated list of elements, surrounded by
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1237 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; i32 42,
1238 i32 11, i32 74, i32 100 &gt;</tt>". Packed constants must have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1239 href="#t_packed">packed type</a>, and the number and types of elements must
1240 match those specified by the type.
1241 </dd>
1242
1243 <dt><b>Zero initialization</b></dt>
1244
1245 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1246 value to zero of <em>any</em> type, including scalar and aggregate types.
1247 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]1248 large arrays) and is always exactly equivalent to using explicit zero
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1249 initializers.
1250 </dd>
1251</dl>
1252
1253</div>
1254
1255<!-- ======================================================================= -->
1256<div class="doc_subsection">
1257 <a name="globalconstants">Global Variable and Function Addresses</a>
1258</div>
1259
1260<div class="doc_text">
1261
1262<p>The addresses of <a href="#globalvars">global variables</a> and <a
1263href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1264constants. These constants are explicitly referenced when the <a
1265href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1266href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1267file:</p>
1268
1269<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1270 %X = global i32 17
1271 %Y = global i32 42
1272 %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1273</pre>
1274
1275</div>
1276
1277<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1278<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1279<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1280 <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]1281 no specific value. Undefined values may be of any type and be used anywhere
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1282 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1283
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1284 <p>Undefined values indicate to the compiler that the program is well defined
1285 no matter what value is used, giving the compiler more freedom to optimize.
1286 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1287</div>
1288
1289<!-- ======================================================================= -->
1290<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1291</div>
1292
1293<div class="doc_text">
1294
1295<p>Constant expressions are used to allow expressions involving other constants
1296to be used as constants. Constant expressions may be of any <a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1297href="#t_firstclass">first class</a> type and may involve any LLVM operation
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1298that does not have side effects (e.g. load and call are not supported). The
1299following is the syntax for constant expressions:</p>
1300
1301<dl>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1302 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1303 <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]1304 than the bit size of TYPE. Both types must be integers.</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1305
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1306 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1307 <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]1308 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]1309
1310 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1311 <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]1312 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]1313
1314 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1315 <dd>Truncate a floating point constant to another floating point type. The
1316 size of CST must be larger than the size of TYPE. Both types must be
1317 floating point.</dd>
1318
1319 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1320 <dd>Floating point extend a constant to another type. The size of CST must be
1321 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1322
1323 <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
1324 <dd>Convert a floating point constant to the corresponding unsigned integer
1325 constant. TYPE must be an integer type. CST must be floating point. If the
1326 value won't fit in the integer type, the results are undefined.</dd>
1327
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1328 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1329 <dd>Convert a floating point constant to the corresponding signed integer
1330 constant. TYPE must be an integer type. CST must be floating point. If the
1331 value won't fit in the integer type, the results are undefined.</dd>
1332
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1333 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1334 <dd>Convert an unsigned integer constant to the corresponding floating point
1335 constant. TYPE must be floating point. CST must be of integer type. If the
1336 value won't fit in the floating point type, the results are undefined.</dd>
1337
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]1338 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1339 <dd>Convert a signed integer constant to the corresponding floating point
1340 constant. TYPE must be floating point. CST must be of integer type. If the
1341 value won't fit in the floating point type, the results are undefined.</dd>
1342
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]1343 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1344 <dd>Convert a pointer typed constant to the corresponding integer constant
1345 TYPE must be an integer type. CST must be of pointer type. The CST value is
1346 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1347
1348 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1349 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1350 pointer type. CST must be of integer type. The CST value is zero extended,
1351 truncated, or unchanged to make it fit in a pointer size. This one is
1352 <i>really</i> dangerous!</dd>
1353
1354 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1355 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1356 identical (same number of bits). The conversion is done as if the CST value
1357 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]1358 with this operator, just the type. This can be used for conversion of
1359 packed types to any other type, as long as they have the same bit width. For
1360 pointers it is only valid to cast to another pointer type.
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]1361 </dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1362
1363 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1364
1365 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1366 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1367 instruction, the index list may have zero or more indexes, which are required
1368 to make sense for the type of "CSTPTR".</dd>
1369
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1370 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1371
1372 <dd>Perform the <a href="#i_select">select operation</a> on
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1373 constants.</dd>
1374
1375 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1376 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1377
1378 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1379 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
Robert Bocchino7e97a6d2006-01-10 19:31:34 +0000[diff] [blame]1380
1381 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1382
1383 <dd>Perform the <a href="#i_extractelement">extractelement
1384 operation</a> on constants.
1385
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1386 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1387
1388 <dd>Perform the <a href="#i_insertelement">insertelement
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1389 operation</a> on constants.</dd>
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]1390
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1391
1392 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1393
1394 <dd>Perform the <a href="#i_shufflevector">shufflevector
Reid Spencer9965ee72006-12-04 19:23:19 +0000[diff] [blame]1395 operation</a> on constants.</dd>
Chris Lattner016a0e52006-04-08 00:13:41 +0000[diff] [blame]1396
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1397 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1398
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1399 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1400 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1401 binary</a> operations. The constraints on operands are the same as those for
1402 the corresponding instruction (e.g. no bitwise operations on floating point
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1403 values are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1404</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1405</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1406
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1407<!-- *********************************************************************** -->
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1408<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1409<!-- *********************************************************************** -->
1410
1411<!-- ======================================================================= -->
1412<div class="doc_subsection">
1413<a name="inlineasm">Inline Assembler Expressions</a>
1414</div>
1415
1416<div class="doc_text">
1417
1418<p>
1419LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1420Module-Level Inline Assembly</a>) through the use of a special value. This
1421value represents the inline assembler as a string (containing the instructions
1422to emit), a list of operand constraints (stored as a string), and a flag that
1423indicates whether or not the inline asm expression has side effects. An example
1424inline assembler expression is:
1425</p>
1426
1427<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1428 i32 (i32) asm "bswap $0", "=r,r"
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1429</pre>
1430
1431<p>
1432Inline assembler expressions may <b>only</b> be used as the callee operand of
1433a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1434</p>
1435
1436<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1437 %X = call i32 asm "<a href="#i_bswap">bswap</a> $0", "=r,r"(i32 %Y)
Chris Lattner98f013c2006-01-25 23:47:57 +0000[diff] [blame]1438</pre>
1439
1440<p>
1441Inline asms with side effects not visible in the constraint list must be marked
1442as having side effects. This is done through the use of the
1443'<tt>sideeffect</tt>' keyword, like so:
1444</p>
1445
1446<pre>
1447 call void asm sideeffect "eieio", ""()
1448</pre>
1449
1450<p>TODO: The format of the asm and constraints string still need to be
1451documented here. Constraints on what can be done (e.g. duplication, moving, etc
1452need to be documented).
1453</p>
1454
1455</div>
1456
1457<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1458<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1459<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1460
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1461<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1462
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1463<p>The LLVM instruction set consists of several different
1464classifications of instructions: <a href="#terminators">terminator
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1465instructions</a>, <a href="#binaryops">binary instructions</a>,
1466<a href="#bitwiseops">bitwise binary instructions</a>, <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1467 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1468instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1469
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1470</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1471
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1472<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1473<div class="doc_subsection"> <a name="terminators">Terminator
1474Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1475
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1476<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1477
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1478<p>As mentioned <a href="#functionstructure">previously</a>, every
1479basic block in a program ends with a "Terminator" instruction, which
1480indicates which block should be executed after the current block is
1481finished. These terminator instructions typically yield a '<tt>void</tt>'
1482value: they produce control flow, not values (the one exception being
1483the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1484<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1485 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1486instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1487the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1488 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1489 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1490
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1491</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1492
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1493<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1494<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1495Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1496<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1497<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1498<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]1499 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1500</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1501<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1502<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1503value) from a function back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1504<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1505returns a value and then causes control flow, and one that just causes
1506control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1507<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1508<p>The '<tt>ret</tt>' instruction may return any '<a
1509 href="#t_firstclass">first class</a>' type. Notice that a function is
1510not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1511instruction inside of the function that returns a value that does not
1512match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1513<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1514<p>When the '<tt>ret</tt>' instruction is executed, control flow
1515returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1516 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1517the instruction after the call. If the caller was an "<a
1518 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1519at the beginning of the "normal" destination block. If the instruction
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1520returns a value, that value shall set the call or invoke instruction's
1521return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1522<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1523<pre> ret i32 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1524 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1525</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1526</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1527<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1528<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1529<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1530<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1531<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]1532</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1533<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1534<p>The '<tt>br</tt>' instruction is used to cause control flow to
1535transfer to a different basic block in the current function. There are
1536two forms of this instruction, corresponding to a conditional branch
1537and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1538<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1539<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1540single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1541unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1542value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1543<h5>Semantics:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1544<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1545argument is evaluated. If the value is <tt>true</tt>, control flows
1546to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1547control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1548<h5>Example:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1549<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]1550 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]1551</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1552<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1553<div class="doc_subsubsection">
1554 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1555</div>
1556
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1557<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1558<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1559
1560<pre>
1561 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1562</pre>
1563
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1564<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1565
1566<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1567several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1568instruction, allowing a branch to occur to one of many possible
1569destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1570
1571
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1572<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1573
1574<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1575comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1576an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1577table is not allowed to contain duplicate constant entries.</p>
1578
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1579<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1580
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1581<p>The <tt>switch</tt> instruction specifies a table of values and
1582destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1583table is searched for the given value. If the value is found, control flow is
1584transfered to the corresponding destination; otherwise, control flow is
1585transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1586
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1587<h5>Implementation:</h5>
1588
1589<p>Depending on properties of the target machine and the particular
1590<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1591ways. For example, it could be generated as a series of chained conditional
1592branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1593
1594<h5>Example:</h5>
1595
1596<pre>
1597 <i>; Emulate a conditional br instruction</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]1598 %Val = <a href="#i_zext">zext</a> i1 %value to i32
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1599 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1600
1601 <i>; Emulate an unconditional br instruction</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1602 switch i32 0, label %dest [ ]
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1603
1604 <i>; Implement a jump table:</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1605 switch i32 %val, label %otherwise [ i32 0, label %onzero
1606 i32 1, label %onone
1607 i32 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1608</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1609</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1610
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1611<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1612<div class="doc_subsubsection">
1613 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1614</div>
1615
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1616<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1617
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1618<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1619
1620<pre>
1621 &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]1622 to label &lt;normal label&gt; unwind label &lt;exception label&gt;
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1623</pre>
1624
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1625<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1626
1627<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1628function, with the possibility of control flow transfer to either the
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1629'<tt>normal</tt>' label or the
1630'<tt>exception</tt>' label. If the callee function returns with the
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1631"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1632"normal" label. If the callee (or any indirect callees) returns with the "<a
John Criswell02fdc6f2005-05-12 16:52:32 +0000[diff] [blame]1633href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
1634continued at the dynamically nearest "exception" label.</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1635
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1636<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1637
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1638<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1639
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1640<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1641 <li>
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]1642 The optional "cconv" marker indicates which <a href="callingconv">calling
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1643 convention</a> the call should use. If none is specified, the call defaults
1644 to using C calling conventions.
1645 </li>
1646 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1647 function value being invoked. In most cases, this is a direct function
1648 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1649 an arbitrary pointer to function value.
1650 </li>
1651
1652 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1653 function to be invoked. </li>
1654
1655 <li>'<tt>function args</tt>': argument list whose types match the function
1656 signature argument types. If the function signature indicates the function
1657 accepts a variable number of arguments, the extra arguments can be
1658 specified. </li>
1659
1660 <li>'<tt>normal label</tt>': the label reached when the called function
1661 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1662
1663 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1664 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1665
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1666</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1667
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1668<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1669
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1670<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1671href="#i_call">call</a></tt>' instruction in most regards. The primary
1672difference is that it establishes an association with a label, which is used by
1673the runtime library to unwind the stack.</p>
1674
1675<p>This instruction is used in languages with destructors to ensure that proper
1676cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1677exception. Additionally, this is important for implementation of
1678'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1679
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1680<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]1681<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1682 %retval = invoke i32 %Test(i32 15) to label %Continue
1683 unwind label %TestCleanup <i>; {i32}:retval set</i>
1684 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
1685 unwind label %TestCleanup <i>; {i32}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1686</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1687</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1688
1689
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1690<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1691
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1692<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1693Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1694
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1695<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1696
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1697<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1698<pre>
1699 unwind
1700</pre>
1701
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1702<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1703
1704<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1705at the first callee in the dynamic call stack which used an <a
1706href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1707primarily used to implement exception handling.</p>
1708
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1709<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1710
1711<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1712immediately halt. The dynamic call stack is then searched for the first <a
1713href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1714execution continues at the "exceptional" destination block specified by the
1715<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1716dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1717</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1718
1719<!-- _______________________________________________________________________ -->
1720
1721<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1722Instruction</a> </div>
1723
1724<div class="doc_text">
1725
1726<h5>Syntax:</h5>
1727<pre>
1728 unreachable
1729</pre>
1730
1731<h5>Overview:</h5>
1732
1733<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1734instruction is used to inform the optimizer that a particular portion of the
1735code is not reachable. This can be used to indicate that the code after a
1736no-return function cannot be reached, and other facts.</p>
1737
1738<h5>Semantics:</h5>
1739
1740<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1741</div>
1742
1743
1744
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1745<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1746<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1747<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1748<p>Binary operators are used to do most of the computation in a
1749program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1750produce a single value. The operands might represent
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1751multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1752The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1753necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1754<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1755</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1756<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1757<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1758Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1759<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1760<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1761<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]1762</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1763<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1764<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1765<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1766<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1767 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1768 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1769Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1770<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1771<p>The value produced is the integer or floating point sum of the two
1772operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1773<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1774<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]1775</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1776</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1777<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1778<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1779Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1780<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1781<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1782<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]1783</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1784<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1785<p>The '<tt>sub</tt>' instruction returns the difference of its two
1786operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1787<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1788instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1789<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1790<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1791 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1792values.
1793This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1794Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1795<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1796<p>The value produced is the integer or floating point difference of
1797the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1798<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1799<pre> &lt;result&gt; = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
1800 &lt;result&gt; = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1801</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1802</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1803<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1804<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1805Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1806<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1807<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1808<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]1809</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1810<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1811<p>The '<tt>mul</tt>' instruction returns the product of its two
1812operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1813<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1814<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1815 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1816values.
1817This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1818Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1819<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1820<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1821two operands.</p>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]1822<p>Because the operands are the same width, the result of an integer
1823multiplication is the same whether the operands should be deemed unsigned or
1824signed.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1825<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1826<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]1827</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1828</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1829<!-- _______________________________________________________________________ -->
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1830<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
1831</a></div>
1832<div class="doc_text">
1833<h5>Syntax:</h5>
1834<pre> &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1835</pre>
1836<h5>Overview:</h5>
1837<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
1838operands.</p>
1839<h5>Arguments:</h5>
1840<p>The two arguments to the '<tt>udiv</tt>' instruction must be
1841<a href="#t_integer">integer</a> values. Both arguments must have identical
1842types. This instruction can also take <a href="#t_packed">packed</a> versions
1843of the values in which case the elements must be integers.</p>
1844<h5>Semantics:</h5>
1845<p>The value produced is the unsigned integer quotient of the two operands. This
1846instruction always performs an unsigned division operation, regardless of
1847whether the arguments are unsigned or not.</p>
1848<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1849<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]1850</pre>
1851</div>
1852<!-- _______________________________________________________________________ -->
1853<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
1854</a> </div>
1855<div class="doc_text">
1856<h5>Syntax:</h5>
1857<pre> &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1858</pre>
1859<h5>Overview:</h5>
1860<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
1861operands.</p>
1862<h5>Arguments:</h5>
1863<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
1864<a href="#t_integer">integer</a> values. Both arguments must have identical
1865types. This instruction can also take <a href="#t_packed">packed</a> versions
1866of the values in which case the elements must be integers.</p>
1867<h5>Semantics:</h5>
1868<p>The value produced is the signed integer quotient of the two operands. This
1869instruction always performs a signed division operation, regardless of whether
1870the arguments are signed or not.</p>
1871<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1872<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]1873</pre>
1874</div>
1875<!-- _______________________________________________________________________ -->
1876<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1877Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1878<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1879<h5>Syntax:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1880<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]1881</pre>
1882<h5>Overview:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1883<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1884operands.</p>
1885<h5>Arguments:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1886<p>The two arguments to the '<tt>div</tt>' instruction must be
1887<a href="#t_floating">floating point</a> values. Both arguments must have
1888identical types. This instruction can also take <a href="#t_packed">packed</a>
1889versions of the values in which case the elements must be floating point.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1890<h5>Semantics:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1891<p>The value produced is the floating point quotient of the two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1892<h5>Example:</h5>
Reid Spencer7e80b0b2006-10-26 06:15:43 +0000[diff] [blame]1893<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]1894</pre>
1895</div>
1896<!-- _______________________________________________________________________ -->
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1897<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
1898</div>
1899<div class="doc_text">
1900<h5>Syntax:</h5>
1901<pre> &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1902</pre>
1903<h5>Overview:</h5>
1904<p>The '<tt>urem</tt>' instruction returns the remainder from the
1905unsigned division of its two arguments.</p>
1906<h5>Arguments:</h5>
1907<p>The two arguments to the '<tt>urem</tt>' instruction must be
1908<a href="#t_integer">integer</a> values. Both arguments must have identical
1909types.</p>
1910<h5>Semantics:</h5>
1911<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
1912This instruction always performs an unsigned division to get the remainder,
1913regardless of whether 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; = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1916</pre>
1917
1918</div>
1919<!-- _______________________________________________________________________ -->
1920<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1921Instruction</a> </div>
1922<div class="doc_text">
1923<h5>Syntax:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1924<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]1925</pre>
1926<h5>Overview:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1927<p>The '<tt>srem</tt>' instruction returns the remainder from the
1928signed division of its two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1929<h5>Arguments:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1930<p>The two arguments to the '<tt>srem</tt>' instruction must be
1931<a href="#t_integer">integer</a> values. Both arguments must have identical
1932types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1933<h5>Semantics:</h5>
Reid Spencer7eb55b32006-11-02 01:53:59 +0000[diff] [blame]1934<p>This instruction returns the <i>remainder</i> of a division (where the result
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1935has the same sign as the divisor), not the <i>modulus</i> (where the
1936result has the same sign as the dividend) of a value. For more
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]1937information about the difference, see <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1938 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1939Math Forum</a>.</p>
1940<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]1941<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]1942</pre>
1943
1944</div>
1945<!-- _______________________________________________________________________ -->
1946<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
1947Instruction</a> </div>
1948<div class="doc_text">
1949<h5>Syntax:</h5>
1950<pre> &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1951</pre>
1952<h5>Overview:</h5>
1953<p>The '<tt>frem</tt>' instruction returns the remainder from the
1954division of its two operands.</p>
1955<h5>Arguments:</h5>
1956<p>The two arguments to the '<tt>frem</tt>' instruction must be
1957<a href="#t_floating">floating point</a> values. Both arguments must have
1958identical types.</p>
1959<h5>Semantics:</h5>
1960<p>This instruction returns the <i>remainder</i> of a division.</p>
1961<h5>Example:</h5>
1962<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]1963</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1964</div>
Robert Bocchino820bc75b2006-02-17 21:18:08 +0000[diff] [blame]1965
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1966<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1967<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1968Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1969<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1970<p>Bitwise binary operators are used to do various forms of
1971bit-twiddling in a program. They are generally very efficient
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1972instructions and can commonly be strength reduced from other
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1973instructions. They require two operands, execute an operation on them,
1974and produce a single value. The resulting value of the bitwise binary
1975operators is always the same type as its first operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1976</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1977<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1978<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1979Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1980<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1981<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1982<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]1983</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1984<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1985<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1986its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1987<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1988<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]1989 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1990identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1991<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1992<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1993<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1994<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1995<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1996 <tbody>
1997 <tr>
1998 <td>In0</td>
1999 <td>In1</td>
2000 <td>Out</td>
2001 </tr>
2002 <tr>
2003 <td>0</td>
2004 <td>0</td>
2005 <td>0</td>
2006 </tr>
2007 <tr>
2008 <td>0</td>
2009 <td>1</td>
2010 <td>0</td>
2011 </tr>
2012 <tr>
2013 <td>1</td>
2014 <td>0</td>
2015 <td>0</td>
2016 </tr>
2017 <tr>
2018 <td>1</td>
2019 <td>1</td>
2020 <td>1</td>
2021 </tr>
2022 </tbody>
2023</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2024</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2025<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2026<pre> &lt;result&gt; = and i32 4, %var <i>; yields {i32}:result = 4 &amp; %var</i>
2027 &lt;result&gt; = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2028 &lt;result&gt; = and i32 4, 8 <i>; yields {i32}:result = 0</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2029</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2030</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2031<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2032<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2033<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2034<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2035<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]2036</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2037<h5>Overview:</h5>
2038<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2039or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2040<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2041<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2042 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2043identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2044<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2045<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2046<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2047<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2048<table border="1" cellspacing="0" cellpadding="4">
2049 <tbody>
2050 <tr>
2051 <td>In0</td>
2052 <td>In1</td>
2053 <td>Out</td>
2054 </tr>
2055 <tr>
2056 <td>0</td>
2057 <td>0</td>
2058 <td>0</td>
2059 </tr>
2060 <tr>
2061 <td>0</td>
2062 <td>1</td>
2063 <td>1</td>
2064 </tr>
2065 <tr>
2066 <td>1</td>
2067 <td>0</td>
2068 <td>1</td>
2069 </tr>
2070 <tr>
2071 <td>1</td>
2072 <td>1</td>
2073 <td>1</td>
2074 </tr>
2075 </tbody>
2076</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2077</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2078<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2079<pre> &lt;result&gt; = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2080 &lt;result&gt; = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2081 &lt;result&gt; = or i32 4, 8 <i>; yields {i32}:result = 12</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2082</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2083</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2084<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2085<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2086Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2087<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2088<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2089<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]2090</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2091<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2092<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2093or of its two operands. The <tt>xor</tt> is used to implement the
2094"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2095<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2096<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2097 href="#t_integer">integer</a> values. Both arguments must have
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2098identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2099<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2100<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2101<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2102<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2103<table border="1" cellspacing="0" cellpadding="4">
2104 <tbody>
2105 <tr>
2106 <td>In0</td>
2107 <td>In1</td>
2108 <td>Out</td>
2109 </tr>
2110 <tr>
2111 <td>0</td>
2112 <td>0</td>
2113 <td>0</td>
2114 </tr>
2115 <tr>
2116 <td>0</td>
2117 <td>1</td>
2118 <td>1</td>
2119 </tr>
2120 <tr>
2121 <td>1</td>
2122 <td>0</td>
2123 <td>1</td>
2124 </tr>
2125 <tr>
2126 <td>1</td>
2127 <td>1</td>
2128 <td>0</td>
2129 </tr>
2130 </tbody>
2131</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2132</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2133<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2134<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2135<pre> &lt;result&gt; = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2136 &lt;result&gt; = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2137 &lt;result&gt; = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2138 &lt;result&gt; = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2139</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2140</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2141<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2142<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2143Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2144<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2145<h5>Syntax:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2146<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2147</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2148<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2149<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2150the left a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2151<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2152<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2153 href="#t_integer">integer</a> type. The second argument must be an '<tt>i8</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2154type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2155<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2156<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2157<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2158<pre> &lt;result&gt; = shl i32 4, i8 %var <i>; yields {i32}:result = 4 &lt;&lt; %var</i>
2159 &lt;result&gt; = shl i32 4, i8 2 <i>; yields {i32}:result = 16</i>
2160 &lt;result&gt; = shl i32 1, i8 10 <i>; yields {i32}:result = 1024</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2161</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2162</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2163<!-- _______________________________________________________________________ -->
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2164<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2165Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2166<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2167<h5>Syntax:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2168<pre> &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2169</pre>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2170
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2171<h5>Overview:</h5>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2172<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2173operand shifted to the right a specified number of bits.</p>
2174
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2175<h5>Arguments:</h5>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2176<p>The first argument to the '<tt>lshr</tt>' instruction must be an <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2177 href="#t_integer">integer</a> type. The second argument must be an '<tt>i8</tt>' type.</p>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2178
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2179<h5>Semantics:</h5>
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]2180<p>This instruction always performs a logical shift right operation. The
2181<tt>var2</tt> most significant bits will be filled with zero bits after the
2182shift.</p>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2183
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2184<h5>Example:</h5>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2185<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2186 &lt;result&gt; = lshr i32 4, i8 1 <i>; yields {i32}:result = 2</i>
2187 &lt;result&gt; = lshr i32 4, i8 2 <i>; yields {i32}:result = 1</i>
2188 &lt;result&gt; = lshr i8 4, i8 3 <i>; yields {i8 }:result = 0</i>
2189 &lt;result&gt; = lshr i8 -2, i8 1 <i>; yields {i8 }:result = 0x7FFFFFFF </i>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2190</pre>
2191</div>
2192
2193<!-- ======================================================================= -->
2194<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2195Instruction</a> </div>
2196<div class="doc_text">
2197
2198<h5>Syntax:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2199<pre> &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, i8 &lt;var2&gt; <i>; yields {ty}:result</i>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2200</pre>
2201
2202<h5>Overview:</h5>
2203<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2204operand shifted to the right a specified number of bits.</p>
2205
2206<h5>Arguments:</h5>
2207<p>The first argument to the '<tt>ashr</tt>' instruction must be an
2208<a href="#t_integer">integer</a> type. The second argument must be an
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2209'<tt>i8</tt>' type.</p>
Reid Spencerfdff9382006-11-08 06:47:33 +0000[diff] [blame]2210
2211<h5>Semantics:</h5>
2212<p>This instruction always performs an arithmetic shift right operation,
2213regardless of whether the arguments are signed or not. The <tt>var2</tt> most
2214significant bits will be filled with the sign bit of <tt>var1</tt>.</p>
2215
2216<h5>Example:</h5>
2217<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2218 &lt;result&gt; = ashr i32 4, i8 1 <i>; yields {i32}:result = 2</i>
2219 &lt;result&gt; = ashr i32 4, i8 2 <i>; yields {i32}:result = 1</i>
2220 &lt;result&gt; = ashr i8 4, i8 3 <i>; yields {i8}:result = 0</i>
2221 &lt;result&gt; = ashr i8 -2, i8 1 <i>; yields {i8 }:result = -1</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2222</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2223</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2224
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2225<!-- ======================================================================= -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2226<div class="doc_subsection">
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2227 <a name="vectorops">Vector Operations</a>
2228</div>
2229
2230<div class="doc_text">
2231
2232<p>LLVM supports several instructions to represent vector operations in a
2233target-independent manner. This instructions cover the element-access and
2234vector-specific operations needed to process vectors effectively. While LLVM
2235does directly support these vector operations, many sophisticated algorithms
2236will want to use target-specific intrinsics to take full advantage of a specific
2237target.</p>
2238
2239</div>
2240
2241<!-- _______________________________________________________________________ -->
2242<div class="doc_subsubsection">
2243 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2244</div>
2245
2246<div class="doc_text">
2247
2248<h5>Syntax:</h5>
2249
2250<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2251 &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]2252</pre>
2253
2254<h5>Overview:</h5>
2255
2256<p>
2257The '<tt>extractelement</tt>' instruction extracts a single scalar
2258element from a packed vector at a specified index.
2259</p>
2260
2261
2262<h5>Arguments:</h5>
2263
2264<p>
2265The first operand of an '<tt>extractelement</tt>' instruction is a
2266value of <a href="#t_packed">packed</a> type. The second operand is
2267an index indicating the position from which to extract the element.
2268The index may be a variable.</p>
2269
2270<h5>Semantics:</h5>
2271
2272<p>
2273The result is a scalar of the same type as the element type of
2274<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2275<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2276results are undefined.
2277</p>
2278
2279<h5>Example:</h5>
2280
2281<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2282 %result = extractelement &lt;4 x i32&gt; %vec, i32 0 <i>; yields i32</i>
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2283</pre>
2284</div>
2285
2286
2287<!-- _______________________________________________________________________ -->
2288<div class="doc_subsubsection">
2289 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2290</div>
2291
2292<div class="doc_text">
2293
2294<h5>Syntax:</h5>
2295
2296<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2297 &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]2298</pre>
2299
2300<h5>Overview:</h5>
2301
2302<p>
2303The '<tt>insertelement</tt>' instruction inserts a scalar
2304element into a packed vector at a specified index.
2305</p>
2306
2307
2308<h5>Arguments:</h5>
2309
2310<p>
2311The first operand of an '<tt>insertelement</tt>' instruction is a
2312value of <a href="#t_packed">packed</a> type. The second operand is a
2313scalar value whose type must equal the element type of the first
2314operand. The third operand is an index indicating the position at
2315which to insert the value. The index may be a variable.</p>
2316
2317<h5>Semantics:</h5>
2318
2319<p>
2320The result is a packed vector of the same type as <tt>val</tt>. Its
2321element values are those of <tt>val</tt> except at position
2322<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2323exceeds the length of <tt>val</tt>, the results are undefined.
2324</p>
2325
2326<h5>Example:</h5>
2327
2328<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2329 %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]2330</pre>
2331</div>
2332
2333<!-- _______________________________________________________________________ -->
2334<div class="doc_subsubsection">
2335 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2336</div>
2337
2338<div class="doc_text">
2339
2340<h5>Syntax:</h5>
2341
2342<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2343 &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]2344</pre>
2345
2346<h5>Overview:</h5>
2347
2348<p>
2349The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2350from two input vectors, returning a vector of the same type.
2351</p>
2352
2353<h5>Arguments:</h5>
2354
2355<p>
2356The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2357with types that match each other and types that match the result of the
2358instruction. The third argument is a shuffle mask, which has the same number
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2359of elements as the other vector type, but whose element type is always 'i32'.
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2360</p>
2361
2362<p>
2363The shuffle mask operand is required to be a constant vector with either
2364constant integer or undef values.
2365</p>
2366
2367<h5>Semantics:</h5>
2368
2369<p>
2370The elements of the two input vectors are numbered from left to right across
2371both of the vectors. The shuffle mask operand specifies, for each element of
2372the result vector, which element of the two input registers the result element
2373gets. The element selector may be undef (meaning "don't care") and the second
2374operand may be undef if performing a shuffle from only one vector.
2375</p>
2376
2377<h5>Example:</h5>
2378
2379<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2380 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2,
2381 &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt; <i>; yields &lt;4 x i32&gt;</i>
2382 %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef,
2383 &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]2384</pre>
2385</div>
2386
Tanya Lattnerb138bbe2006-04-14 19:24:33 +0000[diff] [blame]2387
Chris Lattnerce83bff2006-04-08 23:07:04 +0000[diff] [blame]2388<!-- ======================================================================= -->
2389<div class="doc_subsection">
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2390 <a name="memoryops">Memory Access and Addressing Operations</a>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2391</div>
2392
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2393<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2394
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2395<p>A key design point of an SSA-based representation is how it
2396represents memory. In LLVM, no memory locations are in SSA form, which
2397makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2398allocate, and free memory in LLVM.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2399
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2400</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2401
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2402<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2403<div class="doc_subsubsection">
2404 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
2405</div>
2406
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2407<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2408
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2409<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2410
2411<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2412 &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]2413</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2414
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2415<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2416
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2417<p>The '<tt>malloc</tt>' instruction allocates memory from the system
2418heap and returns a pointer to it.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2419
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2420<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2421
2422<p>The '<tt>malloc</tt>' instruction allocates
2423<tt>sizeof(&lt;type&gt;)*NumElements</tt>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]2424bytes of memory from the operating system and returns a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2425appropriate type to the program. If "NumElements" is specified, it is the
2426number of elements allocated. If an alignment is specified, the value result
2427of the allocation is guaranteed to be aligned to at least that boundary. If
2428not specified, or if zero, the target can choose to align the allocation on any
2429convenient boundary.</p>
2430
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2431<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2432
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2433<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2434
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2435<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
2436a pointer is returned.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2437
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2438<h5>Example:</h5>
2439
2440<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2441 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2442
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2443 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
2444 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
2445 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
2446 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
2447 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2448</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2449</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2450
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2451<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2452<div class="doc_subsubsection">
2453 <a name="i_free">'<tt>free</tt>' Instruction</a>
2454</div>
2455
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2456<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2457
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2458<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2459
2460<pre>
2461 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2462</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2463
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2464<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2465
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2466<p>The '<tt>free</tt>' instruction returns memory back to the unused
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2467memory heap to be reallocated in the future.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2468
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2469<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2470
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2471<p>'<tt>value</tt>' shall be a pointer value that points to a value
2472that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
2473instruction.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2474
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2475<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2476
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2477<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2478after this instruction executes.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2479
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2480<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2481
2482<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2483 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
2484 free [4 x i8]* %array
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2485</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2486</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2487
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2488<!-- _______________________________________________________________________ -->
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2489<div class="doc_subsubsection">
2490 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
2491</div>
2492
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2493<div class="doc_text">
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2494
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2495<h5>Syntax:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2496
2497<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2498 &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]2499</pre>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2500
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2501<h5>Overview:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2502
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2503<p>The '<tt>alloca</tt>' instruction allocates memory on the current
2504stack frame of the procedure that is live until the current function
2505returns to its caller.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2506
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2507<h5>Arguments:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2508
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2509<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2510bytes of memory on the runtime stack, returning a pointer of the
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2511appropriate type to the program. If "NumElements" is specified, it is the
2512number of elements allocated. If an alignment is specified, the value result
2513of the allocation is guaranteed to be aligned to at least that boundary. If
2514not specified, or if zero, the target can choose to align the allocation on any
2515convenient boundary.</p>
2516
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2517<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2518
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2519<h5>Semantics:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2520
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2521<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2522memory is automatically released when the function returns. The '<tt>alloca</tt>'
2523instruction is commonly used to represent automatic variables that must
2524have an address available. When the function returns (either with the <tt><a
John Criswellc932bef2005-05-12 16:55:34 +0000[diff] [blame]2525 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]2526instructions), the memory is reclaimed.</p>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2527
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2528<h5>Example:</h5>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2529
2530<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2531 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
2532 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
2533 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
2534 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2535</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2536</div>
Chris Lattner54611b42005-11-06 08:02:57 +0000[diff] [blame]2537
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2538<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2539<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
2540Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2541<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2542<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2543<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]2544<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2545<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2546<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2547<p>The argument to the '<tt>load</tt>' instruction specifies the memory
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2548address from which to load. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]2549 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2550marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2551the number or order of execution of this <tt>load</tt> with other
2552volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
2553instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2554<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2555<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2556<h5>Examples:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2557<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2558 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2559 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2560 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2561</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2562</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2563<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2564<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
2565Instruction</a> </div>
Reid Spencera89fb182006-11-09 21:18:01 +0000[diff] [blame]2566<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2567<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2568<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]2569 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]2570</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2571<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2572<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2573<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2574<p>There are two arguments to the '<tt>store</tt>' instruction: a value
John Criswell4c0cf7f2005-10-24 16:17:18 +0000[diff] [blame]2575to 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]2576operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2577operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2578optimizer is not allowed to modify the number or order of execution of
2579this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
2580 href="#i_store">store</a></tt> instructions.</p>
2581<h5>Semantics:</h5>
2582<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
2583at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2584<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2585<pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2586 <a
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2587 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
2588 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2589</pre>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2590</div>
2591
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2592<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2593<div class="doc_subsubsection">
2594 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
2595</div>
2596
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2597<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2598<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2599<pre>
2600 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
2601</pre>
2602
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2603<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2604
2605<p>
2606The '<tt>getelementptr</tt>' instruction is used to get the address of a
2607subelement of an aggregate data structure.</p>
2608
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2609<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2610
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2611<p>This instruction takes a list of integer operands that indicate what
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2612elements of the aggregate object to index to. The actual types of the arguments
2613provided depend on the type of the first pointer argument. The
2614'<tt>getelementptr</tt>' instruction is used to index down through the type
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]2615levels 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]2616structure, only <tt>i32</tt> integer constants are allowed. When indexing
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2617into an array or pointer, only integers of 32 or 64 bits are allowed, and will
2618be sign extended to 64-bit values.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2619
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2620<p>For example, let's consider a C code fragment and how it gets
2621compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2622
2623<pre>
2624 struct RT {
2625 char A;
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2626 i32 B[10][20];
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2627 char C;
2628 };
2629 struct ST {
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2630 i32 X;
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2631 double Y;
2632 struct RT Z;
2633 };
2634
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2635 define i32 *foo(struct ST *s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2636 return &amp;s[1].Z.B[5][13];
2637 }
2638</pre>
2639
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2640<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2641
2642<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2643 %RT = type { i8 , [10 x [20 x i32]], i8 }
2644 %ST = type { i32, double, %RT }
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2645
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2646 implementation
2647
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2648 define i32* %foo(%ST* %s) {
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]2649 entry:
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2650 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
2651 ret i32* %reg
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2652 }
2653</pre>
2654
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2655<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2656
2657<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
John Criswell4a3327e2005-05-13 22:25:59 +0000[diff] [blame]2658on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
Reid Spencercee005c2006-12-04 21:29:24 +0000[diff] [blame]2659and <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]2660<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]2661to 64-bits. <a href="#t_struct">Structure</a> types, require <tt>i32</tt>
Reid Spencerc0312692006-12-03 16:53:48 +0000[diff] [blame]2662<b>constants</b>.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2663
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2664<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]2665type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2666}</tt>' type, a structure. The second index indexes into the third element of
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2667the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
2668i8 }</tt>' type, another structure. The third index indexes into the second
2669element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2670array. The two dimensions of the array are subscripted into, yielding an
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2671'<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
2672to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2673
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2674<p>Note that it is perfectly legal to index partially through a
2675structure, returning a pointer to an inner element. Because of this,
2676the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2677
2678<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2679 define i32* %foo(%ST* %s) {
2680 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
2681 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
2682 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
2683 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
2684 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
2685 ret i32* %t5
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2686 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2687</pre>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2688
2689<p>Note that it is undefined to access an array out of bounds: array and
2690pointer indexes must always be within the defined bounds of the array type.
2691The one exception for this rules is zero length arrays. These arrays are
2692defined to be accessible as variable length arrays, which requires access
2693beyond the zero'th element.</p>
2694
Chris Lattner6ab66722006-08-15 00:45:58 +0000[diff] [blame]2695<p>The getelementptr instruction is often confusing. For some more insight
2696into how it works, see <a href="GetElementPtr.html">the getelementptr
2697FAQ</a>.</p>
2698
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]2699<h5>Example:</h5>
Chris Lattnerc0ad71e2005-06-24 17:22:57 +0000[diff] [blame]2700
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2701<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2702 <i>; yields [12 x i8]*:aptr</i>
2703 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2704</pre>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]2705</div>
Reid Spencer443460a2006-11-09 21:15:49 +0000[diff] [blame]2706
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2707<!-- ======================================================================= -->
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2708<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2709</div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2710<div class="doc_text">
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]2711<p>The instructions in this category are the conversion instructions (casting)
2712which all take a single operand and a type. They perform various bit conversions
2713on the operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2714</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2715
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2716<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2717<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2718 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
2719</div>
2720<div class="doc_text">
2721
2722<h5>Syntax:</h5>
2723<pre>
2724 &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2725</pre>
2726
2727<h5>Overview:</h5>
2728<p>
2729The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
2730</p>
2731
2732<h5>Arguments:</h5>
2733<p>
2734The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
2735be 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]2736and type of the result, which must be an <a href="#t_integer">integer</a>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2737type. The bit size of <tt>value</tt> must be larger than the bit size of
2738<tt>ty2</tt>. Equal sized types are not allowed.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2739
2740<h5>Semantics:</h5>
2741<p>
2742The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2743and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
2744larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
2745It will always truncate bits.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2746
2747<h5>Example:</h5>
2748<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2749 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2750 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
2751 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2752</pre>
2753</div>
2754
2755<!-- _______________________________________________________________________ -->
2756<div class="doc_subsubsection">
2757 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
2758</div>
2759<div class="doc_text">
2760
2761<h5>Syntax:</h5>
2762<pre>
2763 &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2764</pre>
2765
2766<h5>Overview:</h5>
2767<p>The '<tt>zext</tt>' instruction zero extends its operand to type
2768<tt>ty2</tt>.</p>
2769
2770
2771<h5>Arguments:</h5>
2772<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]2773<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2774also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2775<tt>value</tt> must be smaller than the bit size of the destination type,
2776<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2777
2778<h5>Semantics:</h5>
2779<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
2780bits until it reaches the size of the destination type, <tt>ty2</tt>. When the
2781the operand and the type are the same size, no bit filling is done and the
2782cast is considered a <i>no-op cast</i> because no bits change (only the type
2783changes).</p>
2784
Reid Spencer07c9c682007-01-12 15:46:11 +0000[diff] [blame]2785<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]2786
2787<h5>Example:</h5>
2788<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2789 %X = zext i32 257 to i64 <i>; yields i64:257</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2790 %Y = zext i1 true to i32 <i>; yields i32:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2791</pre>
2792</div>
2793
2794<!-- _______________________________________________________________________ -->
2795<div class="doc_subsubsection">
2796 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
2797</div>
2798<div class="doc_text">
2799
2800<h5>Syntax:</h5>
2801<pre>
2802 &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2803</pre>
2804
2805<h5>Overview:</h5>
2806<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
2807
2808<h5>Arguments:</h5>
2809<p>
2810The '<tt>sext</tt>' instruction takes a value to cast, which must be of
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]2811<a href="#t_integer">integer</a> type, and a type to cast it to, which must
2812also be of <a href="#t_integer">integer</a> type. The bit size of the
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2813<tt>value</tt> must be smaller than the bit size of the destination type,
2814<tt>ty2</tt>.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2815
2816<h5>Semantics:</h5>
2817<p>
2818The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
2819bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
2820the type <tt>ty2</tt>. When the the operand and the type are the same size,
2821no bit filling is done and the cast is considered a <i>no-op cast</i> because
2822no bits change (only the type changes).</p>
2823
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2824<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]2825
2826<h5>Example:</h5>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2827<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2828 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2829 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2830</pre>
2831</div>
2832
2833<!-- _______________________________________________________________________ -->
2834<div class="doc_subsubsection">
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2835 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
2836</div>
2837
2838<div class="doc_text">
2839
2840<h5>Syntax:</h5>
2841
2842<pre>
2843 &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2844</pre>
2845
2846<h5>Overview:</h5>
2847<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
2848<tt>ty2</tt>.</p>
2849
2850
2851<h5>Arguments:</h5>
2852<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
2853 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
2854cast it to. The size of <tt>value</tt> must be larger than the size of
2855<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
2856<i>no-op cast</i>.</p>
2857
2858<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2859<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
2860<a href="#t_floating">floating point</a> type to a smaller
2861<a href="#t_floating">floating point</a> type. If the value cannot fit within
2862the destination type, <tt>ty2</tt>, then the results are undefined.</p>
Reid Spencer2e2740d2006-11-09 21:48:10 +0000[diff] [blame]2863
2864<h5>Example:</h5>
2865<pre>
2866 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
2867 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
2868</pre>
2869</div>
2870
2871<!-- _______________________________________________________________________ -->
2872<div class="doc_subsubsection">
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2873 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
2874</div>
2875<div class="doc_text">
2876
2877<h5>Syntax:</h5>
2878<pre>
2879 &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2880</pre>
2881
2882<h5>Overview:</h5>
2883<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
2884floating point value.</p>
2885
2886<h5>Arguments:</h5>
2887<p>The '<tt>fpext</tt>' instruction takes a
2888<a href="#t_floating">floating point</a> <tt>value</tt> to cast,
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2889and a <a href="#t_floating">floating point</a> type to cast it to. The source
2890type must be smaller than the destination type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2891
2892<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2893<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
2894<a href="t_floating">floating point</a> type to a larger
2895<a href="t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
2896used to make a <i>no-op cast</i> because it always changes bits. Use
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]2897<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]2898
2899<h5>Example:</h5>
2900<pre>
2901 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
2902 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
2903</pre>
2904</div>
2905
2906<!-- _______________________________________________________________________ -->
2907<div class="doc_subsubsection">
Reid Spencer2eadb532007-01-21 00:29:26 +0000[diff] [blame]2908 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2909</div>
2910<div class="doc_text">
2911
2912<h5>Syntax:</h5>
2913<pre>
2914 &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
2915</pre>
2916
2917<h5>Overview:</h5>
2918<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
2919unsigned integer equivalent of type <tt>ty2</tt>.
2920</p>
2921
2922<h5>Arguments:</h5>
2923<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a
2924<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]2925must be an <a href="#t_integer">integer</a> type.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2926
2927<h5>Semantics:</h5>
2928<p> The '<tt>fp2uint</tt>' instruction converts its
2929<a href="#t_floating">floating point</a> operand into the nearest (rounding
2930towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
2931the results are undefined.</p>
2932
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2933<p>When converting to i1, the conversion is done as a comparison against
2934zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2935If 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]2936
2937<h5>Example:</h5>
2938<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2939 %X = fp2uint double 123.0 to i32 <i>; yields i32:123</i>
2940 %Y = fp2uint float 1.0E+300 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2941 %X = fp2uint float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2942</pre>
2943</div>
2944
2945<!-- _______________________________________________________________________ -->
2946<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2947 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2948</div>
2949<div class="doc_text">
2950
2951<h5>Syntax:</h5>
2952<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2953 &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]2954</pre>
2955
2956<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2957<p>The '<tt>fptosi</tt>' instruction converts
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2958<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]2959</p>
2960
2961
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2962<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2963<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]2964<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]2965must also be an <a href="#t_integer">integer</a> type.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2966
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2967<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2968<p>The '<tt>fptosi</tt>' instruction converts its
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2969<a href="#t_floating">floating point</a> operand into the nearest (rounding
2970towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
2971the results are undefined.</p>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2972
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2973<p>When converting to i1, the conversion is done as a comparison against
2974zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>.
2975If 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]2976
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2977<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2978<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]2979 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
2980 %Y = fptosi float 1.0E-247 to i1 <i>; yields i1:true</i>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]2981 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2982</pre>
2983</div>
2984
2985<!-- _______________________________________________________________________ -->
2986<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2987 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2988</div>
2989<div class="doc_text">
2990
2991<h5>Syntax:</h5>
2992<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2993 &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]2994</pre>
2995
2996<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]2997<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]2998integer and converts that value to the <tt>ty2</tt> type.</p>
2999
3000
3001<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3002<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]3003<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]3004be a <a href="#t_floating">floating point</a> type.</p>
3005
3006<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3007<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3008integer quantity and converts it to the corresponding floating point value. If
3009the value cannot fit in the floating point value, the results are undefined.</p>
3010
3011
3012<h5>Example:</h5>
3013<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3014 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3015 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3016</pre>
3017</div>
3018
3019<!-- _______________________________________________________________________ -->
3020<div class="doc_subsubsection">
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3021 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3022</div>
3023<div class="doc_text">
3024
3025<h5>Syntax:</h5>
3026<pre>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3027 &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]3028</pre>
3029
3030<h5>Overview:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3031<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3032integer and converts that value to the <tt>ty2</tt> type.</p>
3033
3034<h5>Arguments:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3035<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]3036<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]3037a <a href="#t_floating">floating point</a> type.</p>
3038
3039<h5>Semantics:</h5>
Reid Spencer51b07252006-11-09 23:03:26 +0000[diff] [blame]3040<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3041integer quantity and converts it to the corresponding floating point value. If
3042the value cannot fit in the floating point value, the results are undefined.</p>
3043
3044<h5>Example:</h5>
3045<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3046 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3047 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3048</pre>
3049</div>
3050
3051<!-- _______________________________________________________________________ -->
3052<div class="doc_subsubsection">
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3053 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3054</div>
3055<div class="doc_text">
3056
3057<h5>Syntax:</h5>
3058<pre>
3059 &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3060</pre>
3061
3062<h5>Overview:</h5>
3063<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3064the integer type <tt>ty2</tt>.</p>
3065
3066<h5>Arguments:</h5>
3067<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3068must be a <a href="t_pointer">pointer</a> value, and a type to cast it to
3069<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3070
3071<h5>Semantics:</h5>
3072<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3073<tt>ty2</tt> by interpreting the pointer value as an integer and either
3074truncating or zero extending that value to the size of the integer type. If
3075<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3076<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3077are the same size, then nothing is done (<i>no-op cast</i>).</p>
3078
3079<h5>Example:</h5>
3080<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3081 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit</i>
3082 %Y = ptrtoint i32* %x to i64 <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3083</pre>
3084</div>
3085
3086<!-- _______________________________________________________________________ -->
3087<div class="doc_subsubsection">
3088 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3089</div>
3090<div class="doc_text">
3091
3092<h5>Syntax:</h5>
3093<pre>
3094 &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
3095</pre>
3096
3097<h5>Overview:</h5>
3098<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3099a pointer type, <tt>ty2</tt>.</p>
3100
3101<h5>Arguments:</h5>
3102<p>The '<tt>inttoptr</tt>' instruction takes an <a href="i_integer">integer</a>
3103value to cast, and a type to cast it to, which must be a
Anton Korobeynikova0554d92007-01-12 19:20:47 +0000[diff] [blame]3104<a href="#t_pointer">pointer</a> type.
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3105
3106<h5>Semantics:</h5>
3107<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3108<tt>ty2</tt> by applying either a zero extension or a truncation depending on
3109the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3110size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3111the size of a pointer then a zero extension is done. If they are the same size,
3112nothing is done (<i>no-op cast</i>).</p>
3113
3114<h5>Example:</h5>
3115<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3116 %X = inttoptr i32 255 to i32* <i>; yields zero extend on 64-bit</i>
3117 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit </i>
3118 %Y = inttoptr i16 0 to i32* <i>; yields zero extend on 32-bit</i>
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3119</pre>
3120</div>
3121
3122<!-- _______________________________________________________________________ -->
3123<div class="doc_subsubsection">
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3124 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3125</div>
3126<div class="doc_text">
3127
3128<h5>Syntax:</h5>
3129<pre>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3130 &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]3131</pre>
3132
3133<h5>Overview:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3134<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3135<tt>ty2</tt> without changing any bits.</p>
3136
3137<h5>Arguments:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3138<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3139a first class value, and a type to cast it to, which must also be a <a
3140 href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
Reid Spencere3db84c2007-01-09 20:08:58 +0000[diff] [blame]3141and the destination type, <tt>ty2</tt>, must be identical. If the source
3142type is a pointer, the destination type must also be a pointer.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3143
3144<h5>Semantics:</h5>
Reid Spencer5b950642006-11-11 23:08:07 +0000[diff] [blame]3145<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
Reid Spencerb7344ff2006-11-11 21:00:47 +0000[diff] [blame]3146<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3147this conversion. The conversion is done as if the <tt>value</tt> had been
3148stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3149converted to other pointer types with this instruction. To convert pointers to
3150other types, use the <a href="#i_inttoptr">inttoptr</a> or
3151<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
Reid Spencer59b6b7d2006-11-08 01:11:31 +0000[diff] [blame]3152
3153<h5>Example:</h5>
3154<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3155 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3156 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3157 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]3158</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3159</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3160
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3161<!-- ======================================================================= -->
3162<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3163<div class="doc_text">
3164<p>The instructions in this category are the "miscellaneous"
3165instructions, which defy better classification.</p>
3166</div>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3167
3168<!-- _______________________________________________________________________ -->
3169<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3170</div>
3171<div class="doc_text">
3172<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3173<pre> &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3174<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3175</pre>
3176<h5>Overview:</h5>
3177<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
3178of its two integer operands.</p>
3179<h5>Arguments:</h5>
3180<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3181the condition code which indicates the kind of comparison to perform. It is not
3182a value, just a keyword. The possibilities for the condition code are:
3183<ol>
3184 <li><tt>eq</tt>: equal</li>
3185 <li><tt>ne</tt>: not equal </li>
3186 <li><tt>ugt</tt>: unsigned greater than</li>
3187 <li><tt>uge</tt>: unsigned greater or equal</li>
3188 <li><tt>ult</tt>: unsigned less than</li>
3189 <li><tt>ule</tt>: unsigned less or equal</li>
3190 <li><tt>sgt</tt>: signed greater than</li>
3191 <li><tt>sge</tt>: signed greater or equal</li>
3192 <li><tt>slt</tt>: signed less than</li>
3193 <li><tt>sle</tt>: signed less or equal</li>
3194</ol>
Chris Lattnerc0f423a2007-01-15 01:54:13 +0000[diff] [blame]3195<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3196<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3197<h5>Semantics:</h5>
3198<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3199the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3200yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3201<ol>
3202 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3203 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3204 </li>
3205 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3206 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3207 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3208 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3209 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3210 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3211 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3212 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3213 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3214 <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
3215 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3216 <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
3217 <li><tt>sge</tt>: interprets the operands as signed values and yields
3218 <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
3219 <li><tt>slt</tt>: interprets the operands as signed values and yields
3220 <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
3221 <li><tt>sle</tt>: interprets the operands as signed values and yields
3222 <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]3223</ol>
3224<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3225values are treated as integers and then compared.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3226
3227<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3228<pre> &lt;result&gt; = icmp eq i32 4, 5 <i>; yields: result=false</i>
3229 &lt;result&gt; = icmp ne float* %X, %X <i>; yields: result=false</i>
3230 &lt;result&gt; = icmp ult i16 4, 5 <i>; yields: result=true</i>
3231 &lt;result&gt; = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3232 &lt;result&gt; = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3233 &lt;result&gt; = icmp sge i16 4, 5 <i>; yields: result=false</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3234</pre>
3235</div>
3236
3237<!-- _______________________________________________________________________ -->
3238<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3239</div>
3240<div class="doc_text">
3241<h5>Syntax:</h5>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3242<pre> &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;
3243<i>; yields {i1}:result</i>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3244</pre>
3245<h5>Overview:</h5>
3246<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
3247of its floating point operands.</p>
3248<h5>Arguments:</h5>
3249<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3250the condition code which indicates the kind of comparison to perform. It is not
3251a value, just a keyword. The possibilities for the condition code are:
3252<ol>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3253 <li><tt>false</tt>: no comparison, always returns false</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3254 <li><tt>oeq</tt>: ordered and equal</li>
3255 <li><tt>ogt</tt>: ordered and greater than </li>
3256 <li><tt>oge</tt>: ordered and greater than or equal</li>
3257 <li><tt>olt</tt>: ordered and less than </li>
3258 <li><tt>ole</tt>: ordered and less than or equal</li>
3259 <li><tt>one</tt>: ordered and not equal</li>
3260 <li><tt>ord</tt>: ordered (no nans)</li>
3261 <li><tt>ueq</tt>: unordered or equal</li>
3262 <li><tt>ugt</tt>: unordered or greater than </li>
3263 <li><tt>uge</tt>: unordered or greater than or equal</li>
3264 <li><tt>ult</tt>: unordered or less than </li>
3265 <li><tt>ule</tt>: unordered or less than or equal</li>
3266 <li><tt>une</tt>: unordered or not equal</li>
3267 <li><tt>uno</tt>: unordered (either nans)</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3268 <li><tt>true</tt>: no comparison, always returns true</li>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3269</ol>
Reid Spencer02e0d1d2006-12-06 07:08:07 +0000[diff] [blame]3270<p>In the preceding, <i>ordered</i> means that neither operand is a QNAN while
3271<i>unordered</i> means that either operand may be a QNAN.</p>
Reid Spencer784ef792007-01-04 05:19:58 +0000[diff] [blame]3272<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
3273<a href="#t_floating">floating point</a> typed. They must have identical
3274types.</p>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3275<p>In the foregoing, <i>ordered</i> means that neither operand is a QNAN and
3276<i>unordered</i> means that either operand is a QNAN.</p>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3277<h5>Semantics:</h5>
3278<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to
3279the condition code given as <tt>cond</tt>. The comparison performed always
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3280yields a <a href="#t_primitive">i1</a> result, as follows:
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3281<ol>
3282 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3283 <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]3284 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3285 <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]3286 <tt>var1</tt> is greather than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3287 <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]3288 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3289 <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]3290 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3291 <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]3292 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3293 <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]3294 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3295 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3296 <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]3297 <tt>var1</tt> is equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3298 <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]3299 <tt>var1</tt> is greater than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3300 <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]3301 <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3302 <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]3303 <tt>var1</tt> is less than <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3304 <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]3305 <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3306 <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]3307 <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
Reid Spencerf69acf32006-11-19 03:00:14 +0000[diff] [blame]3308 <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]3309 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
3310</ol>
Reid Spencerc828a0e2006-11-18 21:50:54 +0000[diff] [blame]3311
3312<h5>Example:</h5>
3313<pre> &lt;result&gt; = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
3314 &lt;result&gt; = icmp one float 4.0, 5.0 <i>; yields: result=true</i>
3315 &lt;result&gt; = icmp olt float 4.0, 5.0 <i>; yields: result=true</i>
3316 &lt;result&gt; = icmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
3317</pre>
3318</div>
3319
Reid Spencer97c5fa42006-11-08 01:18:52 +0000[diff] [blame]3320<!-- _______________________________________________________________________ -->
3321<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
3322Instruction</a> </div>
3323<div class="doc_text">
3324<h5>Syntax:</h5>
3325<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
3326<h5>Overview:</h5>
3327<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
3328the SSA graph representing the function.</p>
3329<h5>Arguments:</h5>
3330<p>The type of the incoming values are specified with the first type
3331field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
3332as arguments, with one pair for each predecessor basic block of the
3333current block. Only values of <a href="#t_firstclass">first class</a>
3334type may be used as the value arguments to the PHI node. Only labels
3335may be used as the label arguments.</p>
3336<p>There must be no non-phi instructions between the start of a basic
3337block and the PHI instructions: i.e. PHI instructions must be first in
3338a basic block.</p>
3339<h5>Semantics:</h5>
3340<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
3341value specified by the parameter, depending on which basic block we
3342came from in the last <a href="#terminators">terminator</a> instruction.</p>
3343<h5>Example:</h5>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3344<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]3345</div>
3346
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3347<!-- _______________________________________________________________________ -->
3348<div class="doc_subsubsection">
3349 <a name="i_select">'<tt>select</tt>' Instruction</a>
3350</div>
3351
3352<div class="doc_text">
3353
3354<h5>Syntax:</h5>
3355
3356<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3357 &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]3358</pre>
3359
3360<h5>Overview:</h5>
3361
3362<p>
3363The '<tt>select</tt>' instruction is used to choose one value based on a
3364condition, without branching.
3365</p>
3366
3367
3368<h5>Arguments:</h5>
3369
3370<p>
3371The '<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.
3372</p>
3373
3374<h5>Semantics:</h5>
3375
3376<p>
3377If the boolean condition evaluates to true, the instruction returns the first
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3378value argument; otherwise, it returns the second value argument.
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3379</p>
3380
3381<h5>Example:</h5>
3382
3383<pre>
Reid Spencer36a15422007-01-12 03:35:51 +0000[diff] [blame]3384 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]3385</pre>
3386</div>
3387
Robert Bocchinof72fdfe2006-01-15 20:48:27 +0000[diff] [blame]3388
3389<!-- _______________________________________________________________________ -->
3390<div class="doc_subsubsection">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3391 <a name="i_call">'<tt>call</tt>' Instruction</a>
3392</div>
3393
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3394<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3395
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3396<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3397<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3398 &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]3399</pre>
3400
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3401<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3402
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3403<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3404
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3405<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3406
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3407<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3408
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3409<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3410 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3411 <p>The optional "tail" marker indicates whether the callee function accesses
3412 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3413 function call is eligible for tail call optimization. Note that calls may
3414 be marked "tail" even if they do not occur before a <a
3415 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3416 </li>
3417 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame]3418 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
3419 convention</a> the call should use. If none is specified, the call defaults
3420 to using C calling conventions.
3421 </li>
3422 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3423 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
3424 being invoked. The argument types must match the types implied by this
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3425 signature. This type can be omitted if the function is not varargs and
3426 if the function type does not return a pointer to a function.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3427 </li>
3428 <li>
3429 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
3430 be invoked. In most cases, this is a direct function invocation, but
3431 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3432 to function value.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3433 </li>
3434 <li>
3435 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]3436 function signature argument types. All arguments must be of
3437 <a href="#t_firstclass">first class</a> type. If the function signature
3438 indicates the function accepts a variable number of arguments, the extra
3439 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3440 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]3441</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3442
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3443<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3444
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3445<p>The '<tt>call</tt>' instruction is used to cause control flow to
3446transfer to a specified function, with its incoming arguments bound to
3447the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
3448instruction in the called function, control flow continues with the
3449instruction after the function call, and the return value of the
3450function is bound to the result argument. This is a simpler case of
3451the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3452
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3453<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3454
3455<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3456 %retval = call i32 %test(i32 %argc)
3457 call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
3458 %X = tail call i32 %foo()
3459 %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]3460</pre>
3461
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3462</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3463
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3464<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3465<div class="doc_subsubsection">
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3466 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3467</div>
3468
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3469<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3470
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3471<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3472
3473<pre>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3474 &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]3475</pre>
3476
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3477<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3478
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3479<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3480the "variable argument" area of a function call. It is used to implement the
3481<tt>va_arg</tt> macro in C.</p>
3482
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3483<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3484
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3485<p>This instruction takes a <tt>va_list*</tt> value and the type of
3486the argument. It returns a value of the specified argument type and
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]3487increments the <tt>va_list</tt> to point to the next argument. Again, the
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3488actual type of <tt>va_list</tt> is target specific.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3489
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3490<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3491
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3492<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
3493type from the specified <tt>va_list</tt> and causes the
3494<tt>va_list</tt> to point to the next argument. For more information,
3495see the variable argument handling <a href="#int_varargs">Intrinsic
3496Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3497
3498<p>It is legal for this instruction to be called in a function which does not
3499take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3500function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3501
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3502<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3503href="#intrinsics">intrinsic function</a> because it takes a type as an
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3504argument.</p>
3505
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]3506<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]3507
3508<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
3509
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3510</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3511
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3512<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3513<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
3514<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3515
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3516<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3517
3518<p>LLVM supports the notion of an "intrinsic function". These functions have
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3519well known names and semantics and are required to follow certain
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3520restrictions. Overall, these instructions represent an extension mechanism for
3521the LLVM language that does not require changing all of the transformations in
3522LLVM to add to the language (or the bytecode reader/writer, the parser,
3523etc...).</p>
3524
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3525<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
3526prefix is reserved in LLVM for intrinsic names; thus, functions may not be named
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3527this. Intrinsic functions must always be external functions: you cannot define
3528the body of intrinsic functions. Intrinsic functions may only be used in call
3529or invoke instructions: it is illegal to take the address of an intrinsic
3530function. Additionally, because intrinsic functions are part of the LLVM
3531language, it is required that they all be documented here if any are added.</p>
3532
3533
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3534<p>To learn how to add an intrinsic function, please see the <a
Chris Lattner90391c12005-05-11 03:35:57 +0000[diff] [blame]3535href="ExtendingLLVM.html">Extending LLVM Guide</a>.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3536</p>
3537
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3538</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3539
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3540<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3541<div class="doc_subsection">
3542 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
3543</div>
3544
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3545<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3546
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3547<p>Variable argument support is defined in LLVM with the <a
Chris Lattner33337472006-01-13 23:26:01 +0000[diff] [blame]3548 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3549intrinsic functions. These functions are related to the similarly
3550named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3551
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3552<p>All of these functions operate on arguments that use a
3553target-specific value type "<tt>va_list</tt>". The LLVM assembly
3554language reference manual does not define what this type is, so all
3555transformations should be prepared to handle intrinsics with any type
3556used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3557
Chris Lattner30b868d2006-05-15 17:26:46 +0000[diff] [blame]3558<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]3559instruction and the variable argument handling intrinsic functions are
3560used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3561
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3562<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3563define i32 %test(i32 %X, ...) {
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3564 ; Initialize variable argument processing
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3565 %ap = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3566 %ap2 = bitcast i8** %ap to i8*
3567 call void %<a href="#i_va_start">llvm.va_start</a>(i8* %ap2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3568
3569 ; Read a single integer argument
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3570 %tmp = va_arg i8 ** %ap, i32
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3571
3572 ; Demonstrate usage of llvm.va_copy and llvm.va_end
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3573 %aq = alloca i8 *
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3574 %aq2 = bitcast i8** %aq to i8*
3575 call void %<a href="#i_va_copy">llvm.va_copy</a>(i8 *%aq2, i8* %ap2)
3576 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %aq2)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3577
3578 ; Stop processing of arguments.
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3579 call void %<a href="#i_va_end">llvm.va_end</a>(i8* %ap2)
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3580 ret i32 %tmp
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3581}
3582</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3583</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3584
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3585<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3586<div class="doc_subsubsection">
3587 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
3588</div>
3589
3590
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3591<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3592<h5>Syntax:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3593<pre> declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3594<h5>Overview:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3595<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
3596<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
3597href="#i_va_arg">va_arg</a></tt>.</p>
3598
3599<h5>Arguments:</h5>
3600
3601<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
3602
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3603<h5>Semantics:</h5>
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3604
3605<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
3606macro available in C. In a target-dependent way, it initializes the
3607<tt>va_list</tt> element the argument points to, so that the next call to
3608<tt>va_arg</tt> will produce the first variable argument passed to the function.
3609Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
3610last argument of the function, the compiler can figure that out.</p>
3611
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3612</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3613
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3614<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3615<div class="doc_subsubsection">
3616 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
3617</div>
3618
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3619<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3620<h5>Syntax:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3621<pre> declare void %llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3622<h5>Overview:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3623
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]3624<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
3625which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
3626or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3627
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3628<h5>Arguments:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3629
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3630<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3631
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3632<h5>Semantics:</h5>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3633
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3634<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]3635macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
3636Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
3637 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
3638with calls to <tt>llvm.va_end</tt>.</p>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3639
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3640</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3641
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3642<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3643<div class="doc_subsubsection">
3644 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
3645</div>
3646
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3647<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3648
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3649<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3650
3651<pre>
Chris Lattnerdb0790c2007-01-08 07:55:15 +0000[diff] [blame]3652 declare void %llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3653</pre>
3654
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3655<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3656
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3657<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
3658the source argument list to the destination argument list.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3659
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3660<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3661
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3662<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]3663The 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]3664
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3665
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]3666<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3667
Andrew Lenharth5fb787c2005-06-18 18:28:17 +0000[diff] [blame]3668<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
3669available in C. In a target-dependent way, it copies the source
3670<tt>va_list</tt> element into the destination list. This intrinsic is necessary
3671because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3672arbitrarily complex and require memory allocation, for example.</p>
3673
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3674</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3675
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3676<!-- ======================================================================= -->
3677<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3678 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
3679</div>
3680
3681<div class="doc_text">
3682
3683<p>
3684LLVM support for <a href="GarbageCollection.html">Accurate Garbage
3685Collection</a> requires the implementation and generation of these intrinsics.
3686These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
3687stack</a>, as well as garbage collector implementations that require <a
3688href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
3689Front-ends for type-safe garbage collected languages should generate these
3690intrinsics to make use of the LLVM garbage collectors. For more details, see <a
3691href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
3692</p>
3693</div>
3694
3695<!-- _______________________________________________________________________ -->
3696<div class="doc_subsubsection">
3697 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
3698</div>
3699
3700<div class="doc_text">
3701
3702<h5>Syntax:</h5>
3703
3704<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3705 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3706</pre>
3707
3708<h5>Overview:</h5>
3709
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]3710<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]3711the code generator, and allows some metadata to be associated with it.</p>
3712
3713<h5>Arguments:</h5>
3714
3715<p>The first argument specifies the address of a stack object that contains the
3716root pointer. The second pointer (which must be either a constant or a global
3717value address) contains the meta-data to be associated with the root.</p>
3718
3719<h5>Semantics:</h5>
3720
3721<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
3722location. At compile-time, the code generator generates information to allow
3723the runtime to find the pointer at GC safe points.
3724</p>
3725
3726</div>
3727
3728
3729<!-- _______________________________________________________________________ -->
3730<div class="doc_subsubsection">
3731 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
3732</div>
3733
3734<div class="doc_text">
3735
3736<h5>Syntax:</h5>
3737
3738<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3739 declare i8 * %llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3740</pre>
3741
3742<h5>Overview:</h5>
3743
3744<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
3745locations, allowing garbage collector implementations that require read
3746barriers.</p>
3747
3748<h5>Arguments:</h5>
3749
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3750<p>The second argument is the address to read from, which should be an address
3751allocated from the garbage collector. The first object is a pointer to the
3752start of the referenced object, if needed by the language runtime (otherwise
3753null).</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3754
3755<h5>Semantics:</h5>
3756
3757<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
3758instruction, but may be replaced with substantially more complex code by the
3759garbage collector runtime, as needed.</p>
3760
3761</div>
3762
3763
3764<!-- _______________________________________________________________________ -->
3765<div class="doc_subsubsection">
3766 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
3767</div>
3768
3769<div class="doc_text">
3770
3771<h5>Syntax:</h5>
3772
3773<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3774 declare void %llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3775</pre>
3776
3777<h5>Overview:</h5>
3778
3779<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
3780locations, allowing garbage collector implementations that require write
3781barriers (such as generational or reference counting collectors).</p>
3782
3783<h5>Arguments:</h5>
3784
Chris Lattnerf9228072006-03-14 20:02:51 +0000[diff] [blame]3785<p>The first argument is the reference to store, the second is the start of the
3786object to store it to, and the third is the address of the field of Obj to
3787store to. If the runtime does not require a pointer to the object, Obj may be
3788null.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]3789
3790<h5>Semantics:</h5>
3791
3792<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
3793instruction, but may be replaced with substantially more complex code by the
3794garbage collector runtime, as needed.</p>
3795
3796</div>
3797
3798
3799
3800<!-- ======================================================================= -->
3801<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3802 <a name="int_codegen">Code Generator Intrinsics</a>
3803</div>
3804
3805<div class="doc_text">
3806<p>
3807These intrinsics are provided by LLVM to expose special features that may only
3808be implemented with code generator support.
3809</p>
3810
3811</div>
3812
3813<!-- _______________________________________________________________________ -->
3814<div class="doc_subsubsection">
3815 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
3816</div>
3817
3818<div class="doc_text">
3819
3820<h5>Syntax:</h5>
3821<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3822 declare i8 *%llvm.returnaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3823</pre>
3824
3825<h5>Overview:</h5>
3826
3827<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3828The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
3829target-specific value indicating the return address of the current function
3830or one of its callers.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3831</p>
3832
3833<h5>Arguments:</h5>
3834
3835<p>
3836The argument to this intrinsic indicates which function to return the address
3837for. Zero indicates the calling function, one indicates its caller, etc. The
3838argument is <b>required</b> to be a constant integer value.
3839</p>
3840
3841<h5>Semantics:</h5>
3842
3843<p>
3844The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
3845the return address of the specified call frame, or zero if it cannot be
3846identified. The value returned by this intrinsic is likely to be incorrect or 0
3847for arguments other than zero, so it should only be used for debugging purposes.
3848</p>
3849
3850<p>
3851Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3852aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3853source-language caller.
3854</p>
3855</div>
3856
3857
3858<!-- _______________________________________________________________________ -->
3859<div class="doc_subsubsection">
3860 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
3861</div>
3862
3863<div class="doc_text">
3864
3865<h5>Syntax:</h5>
3866<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3867 declare i8 *%llvm.frameaddress(i32 &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3868</pre>
3869
3870<h5>Overview:</h5>
3871
3872<p>
Chris Lattnerc1fb4262006-10-15 20:05:59 +0000[diff] [blame]3873The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
3874target-specific frame pointer value for the specified stack frame.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3875</p>
3876
3877<h5>Arguments:</h5>
3878
3879<p>
3880The argument to this intrinsic indicates which function to return the frame
3881pointer for. Zero indicates the calling function, one indicates its caller,
3882etc. The argument is <b>required</b> to be a constant integer value.
3883</p>
3884
3885<h5>Semantics:</h5>
3886
3887<p>
3888The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
3889the frame address of the specified call frame, or zero if it cannot be
3890identified. The value returned by this intrinsic is likely to be incorrect or 0
3891for arguments other than zero, so it should only be used for debugging purposes.
3892</p>
3893
3894<p>
3895Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]3896aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3897source-language caller.
3898</p>
3899</div>
3900
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3901<!-- _______________________________________________________________________ -->
3902<div class="doc_subsubsection">
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3903 <a name="i_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
3904</div>
3905
3906<div class="doc_text">
3907
3908<h5>Syntax:</h5>
3909<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3910 declare i8 *%llvm.stacksave()
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3911</pre>
3912
3913<h5>Overview:</h5>
3914
3915<p>
3916The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
3917the function stack, for use with <a href="#i_stackrestore">
3918<tt>llvm.stackrestore</tt></a>. This is useful for implementing language
3919features like scoped automatic variable sized arrays in C99.
3920</p>
3921
3922<h5>Semantics:</h5>
3923
3924<p>
3925This intrinsic returns a opaque pointer value that can be passed to <a
3926href="#i_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
3927<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
3928<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
3929state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
3930practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
3931that were allocated after the <tt>llvm.stacksave</tt> was executed.
3932</p>
3933
3934</div>
3935
3936<!-- _______________________________________________________________________ -->
3937<div class="doc_subsubsection">
3938 <a name="i_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
3939</div>
3940
3941<div class="doc_text">
3942
3943<h5>Syntax:</h5>
3944<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3945 declare void %llvm.stackrestore(i8 * %ptr)
Chris Lattner2f0f0012006-01-13 02:03:13 +0000[diff] [blame]3946</pre>
3947
3948<h5>Overview:</h5>
3949
3950<p>
3951The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
3952the function stack to the state it was in when the corresponding <a
3953href="#llvm.stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
3954useful for implementing language features like scoped automatic variable sized
3955arrays in C99.
3956</p>
3957
3958<h5>Semantics:</h5>
3959
3960<p>
3961See the description for <a href="#i_stacksave"><tt>llvm.stacksave</tt></a>.
3962</p>
3963
3964</div>
3965
3966
3967<!-- _______________________________________________________________________ -->
3968<div class="doc_subsubsection">
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3969 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
3970</div>
3971
3972<div class="doc_text">
3973
3974<h5>Syntax:</h5>
3975<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]3976 declare void %llvm.prefetch(i8 * &lt;address&gt;,
3977 i32 &lt;rw&gt;, i32 &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3978</pre>
3979
3980<h5>Overview:</h5>
3981
3982
3983<p>
3984The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]3985a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
3986no
3987effect on the behavior of the program but can change its performance
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]3988characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3989</p>
3990
3991<h5>Arguments:</h5>
3992
3993<p>
3994<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
3995determining if the fetch should be for a read (0) or write (1), and
3996<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]3997locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]3998<tt>locality</tt> arguments must be constant integers.
3999</p>
4000
4001<h5>Semantics:</h5>
4002
4003<p>
4004This intrinsic does not modify the behavior of the program. In particular,
4005prefetches cannot trap and do not produce a value. On targets that support this
4006intrinsic, the prefetch can provide hints to the processor cache for better
4007performance.
4008</p>
4009
4010</div>
4011
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4012<!-- _______________________________________________________________________ -->
4013<div class="doc_subsubsection">
4014 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4015</div>
4016
4017<div class="doc_text">
4018
4019<h5>Syntax:</h5>
4020<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4021 declare void %llvm.pcmarker( i32 &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4022</pre>
4023
4024<h5>Overview:</h5>
4025
4026
4027<p>
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4028The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4029(PC) in a region of
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4030code to simulators and other tools. The method is target specific, but it is
4031expected that the marker will use exported symbols to transmit the PC of the marker.
Jeff Cohendc6bfea2005-11-11 02:15:27 +0000[diff] [blame]4032The marker makes no guarantees that it will remain with any specific instruction
Chris Lattnere64d41d2005-11-15 06:07:55 +0000[diff] [blame]4033after optimizations. It is possible that the presence of a marker will inhibit
Chris Lattnerb40261e2006-03-24 07:16:10 +0000[diff] [blame]4034optimizations. The intended use is to be inserted after optimizations to allow
John Criswell88190562005-05-16 16:17:45 +0000[diff] [blame]4035correlations of simulation runs.
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]4036</p>
4037
4038<h5>Arguments:</h5>
4039
4040<p>
4041<tt>id</tt> is a numerical id identifying the marker.
4042</p>
4043
4044<h5>Semantics:</h5>
4045
4046<p>
4047This intrinsic does not modify the behavior of the program. Backends that do not
4048support this intrinisic may ignore it.
4049</p>
4050
4051</div>
4052
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4053<!-- _______________________________________________________________________ -->
4054<div class="doc_subsubsection">
4055 <a name="i_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4056</div>
4057
4058<div class="doc_text">
4059
4060<h5>Syntax:</h5>
4061<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4062 declare i64 %llvm.readcyclecounter( )
Andrew Lenharth01aa5632005-11-11 16:47:30 +0000[diff] [blame]4063</pre>
4064
4065<h5>Overview:</h5>
4066
4067
4068<p>
4069The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4070counter register (or similar low latency, high accuracy clocks) on those targets
4071that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4072As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4073should only be used for small timings.
4074</p>
4075
4076<h5>Semantics:</h5>
4077
4078<p>
4079When directly supported, reading the cycle counter should not modify any memory.
4080Implementations are allowed to either return a application specific value or a
4081system wide value. On backends without support, this is lowered to a constant 0.
4082</p>
4083
4084</div>
4085
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4086<!-- ======================================================================= -->
4087<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4088 <a name="int_libc">Standard C Library Intrinsics</a>
4089</div>
4090
4091<div class="doc_text">
4092<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4093LLVM provides intrinsics for a few important standard C library functions.
4094These intrinsics allow source-language front-ends to pass information about the
4095alignment of the pointer arguments to the code generator, providing opportunity
4096for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4097</p>
4098
4099</div>
4100
4101<!-- _______________________________________________________________________ -->
4102<div class="doc_subsubsection">
4103 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
4104</div>
4105
4106<div class="doc_text">
4107
4108<h5>Syntax:</h5>
4109<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4110 declare void %llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4111 i32 &lt;len&gt;, i32 &lt;align&gt;)
4112 declare void %llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4113 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4114</pre>
4115
4116<h5>Overview:</h5>
4117
4118<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4119The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4120location to the destination location.
4121</p>
4122
4123<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4124Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
4125intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4126</p>
4127
4128<h5>Arguments:</h5>
4129
4130<p>
4131The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4132the source. The third argument is an integer argument
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4133specifying the number of bytes to copy, and the fourth argument is the alignment
4134of the source and destination locations.
4135</p>
4136
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4137<p>
4138If 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]4139the caller guarantees that both the source and destination pointers are aligned
4140to that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4141</p>
4142
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4143<h5>Semantics:</h5>
4144
4145<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4146The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]4147location to the destination location, which are not allowed to overlap. It
4148copies "len" bytes of memory over. If the argument is known to be aligned to
4149some boundary, this can be specified as the fourth argument, otherwise it should
4150be set to 0 or 1.
4151</p>
4152</div>
4153
4154
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4155<!-- _______________________________________________________________________ -->
4156<div class="doc_subsubsection">
4157 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
4158</div>
4159
4160<div class="doc_text">
4161
4162<h5>Syntax:</h5>
4163<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4164 declare void %llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4165 i32 &lt;len&gt;, i32 &lt;align&gt;)
4166 declare void %llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
4167 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4168</pre>
4169
4170<h5>Overview:</h5>
4171
4172<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4173The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
4174location to the destination location. It is similar to the
4175'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4176</p>
4177
4178<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4179Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
4180intrinsics do not return a value, and takes an extra alignment argument.
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4181</p>
4182
4183<h5>Arguments:</h5>
4184
4185<p>
4186The first argument is a pointer to the destination, the second is a pointer to
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4187the source. The third argument is an integer argument
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4188specifying the number of bytes to copy, and the fourth argument is the alignment
4189of the source and destination locations.
4190</p>
4191
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4192<p>
4193If 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]4194the caller guarantees that the source and destination pointers are aligned to
4195that boundary.
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]4196</p>
4197
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4198<h5>Semantics:</h5>
4199
4200<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4201The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]4202location to the destination location, which may overlap. It
4203copies "len" bytes of memory over. If the argument is known to be aligned to
4204some boundary, this can be specified as the fourth argument, otherwise it should
4205be set to 0 or 1.
4206</p>
4207</div>
4208
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4209
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4210<!-- _______________________________________________________________________ -->
4211<div class="doc_subsubsection">
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4212 <a name="i_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4213</div>
4214
4215<div class="doc_text">
4216
4217<h5>Syntax:</h5>
4218<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4219 declare void %llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4220 i32 &lt;len&gt;, i32 &lt;align&gt;)
4221 declare void %llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
4222 i64 &lt;len&gt;, i32 &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4223</pre>
4224
4225<h5>Overview:</h5>
4226
4227<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4228The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4229byte value.
4230</p>
4231
4232<p>
4233Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
4234does not return a value, and takes an extra alignment argument.
4235</p>
4236
4237<h5>Arguments:</h5>
4238
4239<p>
4240The first argument is a pointer to the destination to fill, the second is the
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4241byte value to fill it with, the third argument is an integer
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4242argument specifying the number of bytes to fill, and the fourth argument is the
4243known alignment of destination location.
4244</p>
4245
4246<p>
4247If 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]4248the caller guarantees that the destination pointer is aligned to that boundary.
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4249</p>
4250
4251<h5>Semantics:</h5>
4252
4253<p>
Chris Lattner0c8b2592006-03-03 00:07:20 +0000[diff] [blame]4254The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
4255the
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]4256destination location. If the argument is known to be aligned to some boundary,
4257this can be specified as the fourth argument, otherwise it should be set to 0 or
42581.
4259</p>
4260</div>
4261
4262
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4263<!-- _______________________________________________________________________ -->
4264<div class="doc_subsubsection">
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]4265 <a name="i_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4266</div>
4267
4268<div class="doc_text">
4269
4270<h5>Syntax:</h5>
4271<pre>
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4272 declare float %llvm.sqrt.f32(float %Val)
4273 declare double %llvm.sqrt.f64(double %Val)
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4274</pre>
4275
4276<h5>Overview:</h5>
4277
4278<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4279The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
Chris Lattner8a8f2e52005-07-21 01:29:16 +0000[diff] [blame]4280returning the same value as the libm '<tt>sqrt</tt>' function would. Unlike
4281<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
4282negative numbers (which allows for better optimization).
4283</p>
4284
4285<h5>Arguments:</h5>
4286
4287<p>
4288The argument and return value are floating point numbers of the same type.
4289</p>
4290
4291<h5>Semantics:</h5>
4292
4293<p>
4294This function returns the sqrt of the specified operand if it is a positive
4295floating point number.
4296</p>
4297</div>
4298
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4299<!-- _______________________________________________________________________ -->
4300<div class="doc_subsubsection">
4301 <a name="i_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
4302</div>
4303
4304<div class="doc_text">
4305
4306<h5>Syntax:</h5>
4307<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4308 declare float %llvm.powi.f32(float %Val, i32 %power)
4309 declare double %llvm.powi.f64(double %Val, i32 %power)
Chris Lattner33b73f92006-09-08 06:34:02 +0000[diff] [blame]4310</pre>
4311
4312<h5>Overview:</h5>
4313
4314<p>
4315The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
4316specified (positive or negative) power. The order of evaluation of
4317multiplications is not defined.
4318</p>
4319
4320<h5>Arguments:</h5>
4321
4322<p>
4323The second argument is an integer power, and the first is a value to raise to
4324that power.
4325</p>
4326
4327<h5>Semantics:</h5>
4328
4329<p>
4330This function returns the first value raised to the second power with an
4331unspecified sequence of rounding operations.</p>
4332</div>
4333
4334
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4335<!-- ======================================================================= -->
4336<div class="doc_subsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4337 <a name="int_manip">Bit Manipulation Intrinsics</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4338</div>
4339
4340<div class="doc_text">
4341<p>
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4342LLVM provides intrinsics for a few important bit manipulation operations.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4343These allow efficient code generation for some algorithms.
4344</p>
4345
4346</div>
4347
4348<!-- _______________________________________________________________________ -->
4349<div class="doc_subsubsection">
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4350 <a name="i_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
4351</div>
4352
4353<div class="doc_text">
4354
4355<h5>Syntax:</h5>
4356<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4357 declare i16 %llvm.bswap.i16(i16 &lt;id&gt;)
4358 declare i32 %llvm.bswap.i32(i32 &lt;id&gt;)
4359 declare i64 %llvm.bswap.i64(i64 &lt;id&gt;)
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4360</pre>
4361
4362<h5>Overview:</h5>
4363
4364<p>
4365The '<tt>llvm.bwsap</tt>' family of intrinsics is used to byteswap a 16, 32 or
436664 bit quantity. These are useful for performing operations on data that is not
4367in the target's native byte order.
4368</p>
4369
4370<h5>Semantics:</h5>
4371
4372<p>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4373The <tt>llvm.bswap.16</tt> intrinsic returns an i16 value that has the high
4374and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
4375intrinsic returns an i32 value that has the four bytes of the input i32
4376swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
4377i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i64</tt>
4378intrinsic extends this concept to 64 bits.
Nate Begeman0f223bb2006-01-13 23:26:38 +0000[diff] [blame]4379</p>
4380
4381</div>
4382
4383<!-- _______________________________________________________________________ -->
4384<div class="doc_subsubsection">
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4385 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4386</div>
4387
4388<div class="doc_text">
4389
4390<h5>Syntax:</h5>
4391<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4392 declare i8 %llvm.ctpop.i8 (i8 &lt;src&gt;)
4393 declare i16 %llvm.ctpop.i16(i16 &lt;src&gt;)
4394 declare i32 %llvm.ctpop.i32(i32 &lt;src&gt;)
4395 declare i64 %llvm.ctpop.i64(i64 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4396</pre>
4397
4398<h5>Overview:</h5>
4399
4400<p>
Chris Lattner069b5bd2006-01-16 22:38:59 +0000[diff] [blame]4401The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
4402value.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4403</p>
4404
4405<h5>Arguments:</h5>
4406
4407<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4408The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4409integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4410</p>
4411
4412<h5>Semantics:</h5>
4413
4414<p>
4415The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
4416</p>
4417</div>
4418
4419<!-- _______________________________________________________________________ -->
4420<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4421 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4422</div>
4423
4424<div class="doc_text">
4425
4426<h5>Syntax:</h5>
4427<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4428 declare i8 %llvm.ctlz.i8 (i8 &lt;src&gt;)
4429 declare i16 %llvm.ctlz.i16(i16 &lt;src&gt;)
4430 declare i32 %llvm.ctlz.i32(i32 &lt;src&gt;)
4431 declare i64 %llvm.ctlz.i64(i64 &lt;src&gt;)
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4432</pre>
4433
4434<h5>Overview:</h5>
4435
4436<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4437The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
4438leading zeros in a variable.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4439</p>
4440
4441<h5>Arguments:</h5>
4442
4443<p>
Chris Lattner573f64e2005-05-07 01:46:40 +0000[diff] [blame]4444The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4445integer type. The return type must match the argument type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4446</p>
4447
4448<h5>Semantics:</h5>
4449
4450<p>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4451The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
4452in 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]4453of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]4454</p>
4455</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]4456
4457
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4458
4459<!-- _______________________________________________________________________ -->
4460<div class="doc_subsubsection">
Chris Lattnerb748c672006-01-16 22:34:14 +0000[diff] [blame]4461 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4462</div>
4463
4464<div class="doc_text">
4465
4466<h5>Syntax:</h5>
4467<pre>
Reid Spencerb5ebf3d2006-12-31 07:07:53 +0000[diff] [blame]4468 declare i8 %llvm.cttz.i8 (i8 &lt;src&gt;)
4469 declare i16 %llvm.cttz.i16(i16 &lt;src&gt;)
4470 declare i32 %llvm.cttz.i32(i32 &lt;src&gt;)
4471 declare i64 %llvm.cttz.i64(i64 &lt;src&gt;)
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4472</pre>
4473
4474<h5>Overview:</h5>
4475
4476<p>
Reid Spencerb4f9a6f2006-01-16 21:12:35 +0000[diff] [blame]4477The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
4478trailing zeros.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4479</p>
4480
4481<h5>Arguments:</h5>
4482
4483<p>
4484The only argument is the value to be counted. The argument may be of any
Reid Spencer3e628eb92007-01-04 16:43:23 +0000[diff] [blame]4485integer type. The return type must match the argument type.
Chris Lattnerefa20fa2005-05-15 19:39:26 +0000[diff] [blame]4486</p>
4487
4488<h5>Semantics:</h5>
4489
4490<p>
4491The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
4492in a variable. If the src == 0 then the result is the size in bits of the type
4493of src. For example, <tt>llvm.cttz(2) = 1</tt>.
4494</p>
4495</div>
4496
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]4497<!-- ======================================================================= -->
4498<div class="doc_subsection">
4499 <a name="int_debugger">Debugger Intrinsics</a>
4500</div>
4501
4502<div class="doc_text">
4503<p>
4504The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
4505are described in the <a
4506href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
4507Debugging</a> document.
4508</p>
4509</div>
4510
4511
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4512<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]4513<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4514<address>
4515 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
4516 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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4518 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
4519
4520 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencerca058542006-03-14 05:39:39 +0000[diff] [blame]4521 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]4522 Last modified: $Date$
4523</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]4524</body>
4525</html>