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gerrit-public.fairphone.software / toolchain / llvm-project / 0132affa894e6e1c6d024ad0b3b38ca77b163eec / . / 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>
26 <li><a href="#functionstructure">Function Structure</a></li>
27 </ol>
28 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]29 <li><a href="#typesystem">Type System</a>
30 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]31 <li><a href="#t_primitive">Primitive Types</a>
32 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]33 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]34 </ol>
35 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]36 <li><a href="#t_derived">Derived Types</a>
37 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]38 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]39 <li><a href="#t_function">Function Type</a></li>
40 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]41 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]42 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]43 <li><a href="#t_opaque">Opaque Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]44 </ol>
45 </li>
46 </ol>
47 </li>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]48 <li><a href="#constants">Constants</a>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]49 <ol>
50 <li><a href="#simpleconstants">Simple Constants</a>
51 <li><a href="#aggregateconstants">Aggregate Constants</a>
52 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
53 <li><a href="#undefvalues">Undefined Values</a>
54 <li><a href="#constantexprs">Constant Expressions</a>
55 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]56 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]57 <li><a href="#instref">Instruction Reference</a>
58 <ol>
59 <li><a href="#terminators">Terminator Instructions</a>
60 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]61 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
62 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]63 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
64 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]65 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]66 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]67 </ol>
68 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]69 <li><a href="#binaryops">Binary Operations</a>
70 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]71 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
72 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
73 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
74 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
75 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]76 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]77 </ol>
78 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]79 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
80 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]81 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]82 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]83 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
84 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
85 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]86 </ol>
87 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]88 <li><a href="#memoryops">Memory Access Operations</a>
89 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]90 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
91 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
92 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
93 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
94 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
95 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
96 </ol>
97 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]98 <li><a href="#otherops">Other Operations</a>
99 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]100 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]101 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]102 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]103 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]104 <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]105 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]106 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]107 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]108 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]109 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]110 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]111 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]112 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
113 <ol>
114 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
115 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
116 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
117 </ol>
118 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]119 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
120 <ol>
121 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
122 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
123 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
124 </ol>
125 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]126 <li><a href="#int_codegen">Code Generator Intrinsics</a>
127 <ol>
128 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
129 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]130 <li><a href="#i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]131 <li><a href="#i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]132 </ol>
133 </li>
134 <li><a href="#int_os">Operating System Intrinsics</a>
135 <ol>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]136 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
137 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]138 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
139 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]140 </ol>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]141 <li><a href="#int_libc">Standard C Library Intrinsics</a>
142 <ol>
143 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]144 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]145 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos9d740622004-06-12 19:19:14 +0000[diff] [blame]146 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]147 </ol>
148 </li>
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]149 <li><a href="#int_count">Bit counting Intrinsics</a>
150 <ol>
151 <li><a href="#int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic </a></li>
152 <li><a href="#int_cttz">'<tt>llvm.cttz</tt>' Intrinsic </a></li>
153 <li><a href="#int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic </a></li>
154 </ol>
155 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]156 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]157 </ol>
158 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]159</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]160
161<div class="doc_author">
162 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
163 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]164</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]165
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]166<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]167<div class="doc_section"> <a name="abstract">Abstract </a></div>
168<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]169
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]170<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]171<p>This document is a reference manual for the LLVM assembly language.
172LLVM is an SSA based representation that provides type safety,
173low-level operations, flexibility, and the capability of representing
174'all' high-level languages cleanly. It is the common code
175representation used throughout all phases of the LLVM compilation
176strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]177</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]178
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]179<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]180<div class="doc_section"> <a name="introduction">Introduction</a> </div>
181<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]182
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]183<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]184
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]185<p>The LLVM code representation is designed to be used in three
186different forms: as an in-memory compiler IR, as an on-disk bytecode
187representation (suitable for fast loading by a Just-In-Time compiler),
188and as a human readable assembly language representation. This allows
189LLVM to provide a powerful intermediate representation for efficient
190compiler transformations and analysis, while providing a natural means
191to debug and visualize the transformations. The three different forms
192of LLVM are all equivalent. This document describes the human readable
193representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]194
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]195<p>The LLVM representation aims to be a light-weight and low-level
196while being expressive, typed, and extensible at the same time. It
197aims to be a "universal IR" of sorts, by being at a low enough level
198that high-level ideas may be cleanly mapped to it (similar to how
199microprocessors are "universal IR's", allowing many source languages to
200be mapped to them). By providing type information, LLVM can be used as
201the target of optimizations: for example, through pointer analysis, it
202can be proven that a C automatic variable is never accessed outside of
203the current function... allowing it to be promoted to a simple SSA
204value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]205
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]206</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]207
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]208<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]209<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]210
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]211<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]212
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]213<p>It is important to note that this document describes 'well formed'
214LLVM assembly language. There is a difference between what the parser
215accepts and what is considered 'well formed'. For example, the
216following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]217
218<pre>
219 %x = <a href="#i_add">add</a> int 1, %x
220</pre>
221
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]222<p>...because the definition of <tt>%x</tt> does not dominate all of
223its uses. The LLVM infrastructure provides a verification pass that may
224be used to verify that an LLVM module is well formed. This pass is
225automatically run by the parser after parsing input assembly, and by
226the optimizer before it outputs bytecode. The violations pointed out
227by the verifier pass indicate bugs in transformation passes or input to
228the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]229
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]230<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]231
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]232<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]233<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]234<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]235
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]236<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]237
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]238<p>LLVM uses three different forms of identifiers, for different
239purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]240
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]241<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]242 <li>Named values are represented as a string of characters with a '%' prefix.
243 For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
244 regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
245 Identifiers which require other characters in their names can be surrounded
246 with quotes. In this way, anything except a <tt>"</tt> character can be used
247 in a name.</li>
248
249 <li>Unnamed values are represented as an unsigned numeric value with a '%'
250 prefix. For example, %12, %2, %44.</li>
251
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]252 <li>Constants, which are described in a <a href="#constants">section about
253 constants</a>, below.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]254</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]255
256<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
257don't need to worry about name clashes with reserved words, and the set of
258reserved words may be expanded in the future without penalty. Additionally,
259unnamed identifiers allow a compiler to quickly come up with a temporary
260variable without having to avoid symbol table conflicts.</p>
261
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]262<p>Reserved words in LLVM are very similar to reserved words in other
263languages. There are keywords for different opcodes ('<tt><a
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]264href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
265href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
266href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>', etc...),
267and others. These reserved words cannot conflict with variable names, because
268none of them start with a '%' character.</p>
269
270<p>Here is an example of LLVM code to multiply the integer variable
271'<tt>%X</tt>' by 8:</p>
272
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]273<p>The easy way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]274
275<pre>
276 %result = <a href="#i_mul">mul</a> uint %X, 8
277</pre>
278
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]279<p>After strength reduction:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]280
281<pre>
282 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
283</pre>
284
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]285<p>And the hard way:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]286
287<pre>
288 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
289 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
290 %result = <a href="#i_add">add</a> uint %1, %1
291</pre>
292
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]293<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
294important lexical features of LLVM:</p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]295
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]296<ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]297
298 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
299 line.</li>
300
301 <li>Unnamed temporaries are created when the result of a computation is not
302 assigned to a named value.</li>
303
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]304 <li>Unnamed temporaries are numbered sequentially</li>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]305
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]306</ol>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]307
308<p>...and it also show a convention that we follow in this document. When
309demonstrating instructions, we will follow an instruction with a comment that
310defines the type and name of value produced. Comments are shown in italic
311text.</p>
312
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]313</div>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]314
315<!-- *********************************************************************** -->
316<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
317<!-- *********************************************************************** -->
318
319<!-- ======================================================================= -->
320<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
321</div>
322
323<div class="doc_text">
324
325<p>LLVM programs are composed of "Module"s, each of which is a
326translation unit of the input programs. Each module consists of
327functions, global variables, and symbol table entries. Modules may be
328combined together with the LLVM linker, which merges function (and
329global variable) definitions, resolves forward declarations, and merges
330symbol table entries. Here is an example of the "hello world" module:</p>
331
332<pre><i>; Declare the string constant as a global constant...</i>
333<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
334 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
335
336<i>; External declaration of the puts function</i>
337<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
338
339<i>; Definition of main function</i>
340int %main() { <i>; int()* </i>
341 <i>; Convert [13x sbyte]* to sbyte *...</i>
342 %cast210 = <a
343 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
344
345 <i>; Call puts function to write out the string to stdout...</i>
346 <a
347 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
348 <a
349 href="#i_ret">ret</a> int 0<br>}<br></pre>
350
351<p>This example is made up of a <a href="#globalvars">global variable</a>
352named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
353function, and a <a href="#functionstructure">function definition</a>
354for "<tt>main</tt>".</p>
355
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]356<p>In general, a module is made up of a list of global values,
357where both functions and global variables are global values. Global values are
358represented by a pointer to a memory location (in this case, a pointer to an
359array of char, and a pointer to a function), and have one of the following <a
360href="#linkage">linkage types</a>.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]361
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]362</div>
363
364<!-- ======================================================================= -->
365<div class="doc_subsection">
366 <a name="linkage">Linkage Types</a>
367</div>
368
369<div class="doc_text">
370
371<p>
372All Global Variables and Functions have one of the following types of linkage:
373</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]374
375<dl>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]376
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]377 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]378
379 <dd>Global values with internal linkage are only directly accessible by
380 objects in the current module. In particular, linking code into a module with
381 an internal global value may cause the internal to be renamed as necessary to
382 avoid collisions. Because the symbol is internal to the module, all
383 references can be updated. This corresponds to the notion of the
384 '<tt>static</tt>' keyword in C, or the idea of "anonymous namespaces" in C++.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]385 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]386
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]387 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]388
389 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt> linkage, with
390 the twist that linking together two modules defining the same
391 <tt>linkonce</tt> globals will cause one of the globals to be discarded. This
392 is typically used to implement inline functions. Unreferenced
393 <tt>linkonce</tt> globals are allowed to be discarded.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]394 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]395
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]396 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]397
398 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
399 except that unreferenced <tt>weak</tt> globals may not be discarded. This is
400 used to implement constructs in C such as "<tt>int X;</tt>" at global scope.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]401 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]402
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]403 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]404
405 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
406 pointer to array type. When two global variables with appending linkage are
407 linked together, the two global arrays are appended together. This is the
408 LLVM, typesafe, equivalent of having the system linker append together
409 "sections" with identical names when .o files are linked.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]410 </dd>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]411
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]412 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]413
414 <dd>If none of the above identifiers are used, the global is externally
415 visible, meaning that it participates in linkage and can be used to resolve
416 external symbol references.
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]417 </dd>
418</dl>
419
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]420<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
421variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
422variable and was linked with this one, one of the two would be renamed,
423preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
424external (i.e., lacking any linkage declarations), they are accessible
425outside of the current module. It is illegal for a function <i>declaration</i>
426to have any linkage type other than "externally visible".</a></p>
Chris Lattnerd79749a2004-12-09 16:36:40 +0000[diff] [blame]427
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]428</div>
429
430<!-- ======================================================================= -->
431<div class="doc_subsection">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]432 <a name="callingconv">Calling Conventions</a>
433</div>
434
435<div class="doc_text">
436
437<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
438and <a href="#i_invoke">invokes</a> can all have an optional calling convention
439specified for the call. The calling convention of any pair of dynamic
440caller/callee must match, or the behavior of the program is undefined. The
441following calling conventions are supported by LLVM, and more may be added in
442the future:</p>
443
444<dl>
445 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
446
447 <dd>This calling convention (the default if no other calling convention is
448 specified) matches the target C calling conventions. This calling convention
449 supports varargs function calls, and tolerates some mismatch in the declared
450 prototype and implemented declaration of the function (as does normal C).
451 </dd>
452
453 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
454
455 <dd>This calling convention attempts to make calls as fast as possible
456 (e.g. by passing things in registers). This calling convention allows the
457 target to use whatever tricks it wants to produce fast code for the target,
458 without having to conform to an externally specified ABI. This calling
459 convention does not support varargs and requires the prototype of all callees
460 to exactly match the prototype of the function definition.
461 </dd>
462
463 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
464
465 <dd>This calling convention attempts to make code in the caller as efficient
466 as possible under the assumption that the call is not commonly executed. As
467 such, these calls often preserve all registers so that the call does not break
468 any live ranges in the caller side. This calling convention does not support
469 varargs and requires the prototype of all callees to exactly match the
470 prototype of the function definition.
471 </dd>
472
473 <dt><b>"<tt>cc &lt;<it>n</it>&gt;</tt>" - Numbered convention</b>:</dt>
474
475 <dd>Any calling convention may be specified by number, allowing
476 target-specific calling conventions to be used. Target specific calling
477 conventions start at 64.
478 </dd>
479
480<p>More calling conventions can be added/defined on an as-needed basis, to
481support pascal conventions or any other well-known target-independent
482convention.</p>
483
484</div>
485
486<!-- ======================================================================= -->
487<div class="doc_subsection">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]488 <a name="globalvars">Global Variables</a>
489</div>
490
491<div class="doc_text">
492
Chris Lattner5d5aede2005-02-12 19:30:21 +0000[diff] [blame]493<p>Global variables define regions of memory allocated at compilation time
494instead of run-time. Global variables may optionally be initialized. A
495variable may be defined as a global "constant", which indicates that the
496contents of the variable will <b>never</b> be modified (enabling better
497optimization, allowing the global data to be placed in the read-only section of
498an executable, etc). Note that variables that need runtime initialization
499cannot be marked "constant", as there is a store to the variable.</p>
500
501<p>
502LLVM explicitly allows <em>declarations</em> of global variables to be marked
503constant, even if the final definition of the global is not. This capability
504can be used to enable slightly better optimization of the program, but requires
505the language definition to guarantee that optimizations based on the
506'constantness' are valid for the translation units that do not include the
507definition.
508</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]509
510<p>As SSA values, global variables define pointer values that are in
511scope (i.e. they dominate) all basic blocks in the program. Global
512variables always define a pointer to their "content" type because they
513describe a region of memory, and all memory objects in LLVM are
514accessed through pointers.</p>
515
516</div>
517
518
519<!-- ======================================================================= -->
520<div class="doc_subsection">
521 <a name="functionstructure">Functions</a>
522</div>
523
524<div class="doc_text">
525
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]526<p>LLVM function definitions consist of an optional <a href="#linkage">linkage
527type</a>, an optional <a href="#callingconv">calling convention</a>, a return
528type, a function name, a (possibly empty) argument list, an opening curly brace,
529a list of basic blocks, and a closing curly brace. LLVM function declarations
530are defined with the "<tt>declare</tt>" keyword, an optional <a
531href="#callingconv">calling convention</a>, a return type, a function name, and
532a possibly empty list of arguments.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]533
534<p>A function definition contains a list of basic blocks, forming the CFG for
535the function. Each basic block may optionally start with a label (giving the
536basic block a symbol table entry), contains a list of instructions, and ends
537with a <a href="#terminators">terminator</a> instruction (such as a branch or
538function return).</p>
539
540<p>The first basic block in program is special in two ways: it is immediately
541executed on entrance to the function, and it is not allowed to have predecessor
542basic blocks (i.e. there can not be any branches to the entry block of a
543function). Because the block can have no predecessors, it also cannot have any
544<a href="#i_phi">PHI nodes</a>.</p>
545
546<p>LLVM functions are identified by their name and type signature. Hence, two
547functions with the same name but different parameter lists or return values are
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]548considered different functions, and LLVM will resolve references to each
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]549appropriately.</p>
550
551</div>
552
553
554
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]555<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]556<div class="doc_section"> <a name="typesystem">Type System</a> </div>
557<!-- *********************************************************************** -->
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]558
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]559<div class="doc_text">
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]560
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]561<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]562intermediate representation. Being typed enables a number of
563optimizations to be performed on the IR directly, without having to do
564extra analyses on the side before the transformation. A strong type
565system makes it easier to read the generated code and enables novel
566analyses and transformations that are not feasible to perform on normal
567three address code representations.</p>
Chris Lattner6af02f32004-12-09 16:11:40 +0000[diff] [blame]568
569</div>
570
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]571<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]572<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]573<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]574<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]575system. The current set of primitive types is as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]576
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]577<table class="layout">
578 <tr class="layout">
579 <td class="left">
580 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]581 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]582 <tr><th>Type</th><th>Description</th></tr>
583 <tr><td><tt>void</tt></td><td>No value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]584 <tr><td><tt>ubyte</tt></td><td>Unsigned 8-bit value</td></tr>
585 <tr><td><tt>ushort</tt></td><td>Unsigned 16-bit value</td></tr>
586 <tr><td><tt>uint</tt></td><td>Unsigned 32-bit value</td></tr>
587 <tr><td><tt>ulong</tt></td><td>Unsigned 64-bit value</td></tr>
588 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]589 <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]590 </tbody>
591 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]592 </td>
593 <td class="right">
594 <table>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]595 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]596 <tr><th>Type</th><th>Description</th></tr>
597 <tr><td><tt>bool</tt></td><td>True or False value</td></tr>
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]598 <tr><td><tt>sbyte</tt></td><td>Signed 8-bit value</td></tr>
599 <tr><td><tt>short</tt></td><td>Signed 16-bit value</td></tr>
600 <tr><td><tt>int</tt></td><td>Signed 32-bit value</td></tr>
601 <tr><td><tt>long</tt></td><td>Signed 64-bit value</td></tr>
602 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]603 </tbody>
604 </table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]605 </td>
606 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]607</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]608</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]609
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]610<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]611<div class="doc_subsubsection"> <a name="t_classifications">Type
612Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]613<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]614<p>These different primitive types fall into a few useful
615classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]616
617<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]618 <tbody>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]619 <tr><th>Classification</th><th>Types</th></tr>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]620 <tr>
621 <td><a name="t_signed">signed</a></td>
622 <td><tt>sbyte, short, int, long, float, double</tt></td>
623 </tr>
624 <tr>
625 <td><a name="t_unsigned">unsigned</a></td>
626 <td><tt>ubyte, ushort, uint, ulong</tt></td>
627 </tr>
628 <tr>
629 <td><a name="t_integer">integer</a></td>
630 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
631 </tr>
632 <tr>
633 <td><a name="t_integral">integral</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]634 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
635 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]636 </tr>
637 <tr>
638 <td><a name="t_floating">floating point</a></td>
639 <td><tt>float, double</tt></td>
640 </tr>
641 <tr>
642 <td><a name="t_firstclass">first class</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]643 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
644 float, double, <a href="#t_pointer">pointer</a>,
645 <a href="#t_packed">packed</a></tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]646 </tr>
647 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]648</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]649
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]650<p>The <a href="#t_firstclass">first class</a> types are perhaps the
651most important. Values of these types are the only ones which can be
652produced by instructions, passed as arguments, or used as operands to
653instructions. This means that all structures and arrays must be
654manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]655</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]656
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]657<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]658<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]659
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]660<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]661
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]662<p>The real power in LLVM comes from the derived types in the system.
663This is what allows a programmer to represent arrays, functions,
664pointers, and other useful types. Note that these derived types may be
665recursive: For example, it is possible to have a two dimensional array.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]666
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]667</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]668
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]669<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]670<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]671
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]672<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]673
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]674<h5>Overview:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]675
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]676<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]677sequentially in memory. The array type requires a size (number of
678elements) and an underlying data type.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]679
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]680<h5>Syntax:</h5>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]681
682<pre>
683 [&lt;# elements&gt; x &lt;elementtype&gt;]
684</pre>
685
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]686<p>The number of elements is a constant integer value, elementtype may
687be any type with a size.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]688
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]689<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]690<table class="layout">
691 <tr class="layout">
692 <td class="left">
693 <tt>[40 x int ]</tt><br/>
694 <tt>[41 x int ]</tt><br/>
695 <tt>[40 x uint]</tt><br/>
696 </td>
697 <td class="left">
698 Array of 40 integer values.<br/>
699 Array of 41 integer values.<br/>
700 Array of 40 unsigned integer values.<br/>
701 </td>
702 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]703</table>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]704<p>Here are some examples of multidimensional arrays:</p>
705<table class="layout">
706 <tr class="layout">
707 <td class="left">
708 <tt>[3 x [4 x int]]</tt><br/>
709 <tt>[12 x [10 x float]]</tt><br/>
710 <tt>[2 x [3 x [4 x uint]]]</tt><br/>
711 </td>
712 <td class="left">
713 3x4 array integer values.<br/>
714 12x10 array of single precision floating point values.<br/>
715 2x3x4 array of unsigned integer values.<br/>
716 </td>
717 </tr>
718</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]719</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]720
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]721<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]722<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]723<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]724<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]725<p>The function type can be thought of as a function signature. It
726consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]727Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]728(which are structures of pointers to functions), for indirect function
729calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]730<p>
731The return type of a function type cannot be an aggregate type.
732</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]733<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]734<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]735<p>Where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
736specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]737which indicates that the function takes a variable number of arguments.
738Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]739 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]740<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]741<table class="layout">
742 <tr class="layout">
743 <td class="left">
744 <tt>int (int)</tt> <br/>
745 <tt>float (int, int *) *</tt><br/>
746 <tt>int (sbyte *, ...)</tt><br/>
747 </td>
748 <td class="left">
749 function taking an <tt>int</tt>, returning an <tt>int</tt><br/>
750 <a href="#t_pointer">Pointer</a> to a function that takes an
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]751 <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]752 returning <tt>float</tt>.<br/>
753 A vararg function that takes at least one <a href="#t_pointer">pointer</a>
754 to <tt>sbyte</tt> (signed char in C), which returns an integer. This is
755 the signature for <tt>printf</tt> in LLVM.<br/>
756 </td>
757 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]758</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]759
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]760</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]761<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]762<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]763<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]764<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]765<p>The structure type is used to represent a collection of data members
766together in memory. The packing of the field types is defined to match
767the ABI of the underlying processor. The elements of a structure may
768be any type that has a size.</p>
769<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
770and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
771field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
772instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]773<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]774<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]775<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]776<table class="layout">
777 <tr class="layout">
778 <td class="left">
779 <tt>{ int, int, int }</tt><br/>
780 <tt>{ float, int (int) * }</tt><br/>
781 </td>
782 <td class="left">
783 a triple of three <tt>int</tt> values<br/>
784 A pair, where the first element is a <tt>float</tt> and the second element
785 is a <a href="#t_pointer">pointer</a> to a <a href="#t_function">function</a>
786 that takes an <tt>int</tt>, returning an <tt>int</tt>.<br/>
787 </td>
788 </tr>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]789</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]790</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]791
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]792<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]793<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]794<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]795<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]796<p>As in many languages, the pointer type represents a pointer or
797reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]798<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]799<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]800<h5>Examples:</h5>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]801<table class="layout">
802 <tr class="layout">
803 <td class="left">
804 <tt>[4x int]*</tt><br/>
805 <tt>int (int *) *</tt><br/>
806 </td>
807 <td class="left">
808 A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
809 four <tt>int</tt> values<br/>
810 A <a href="#t_pointer">pointer</a> to a <a
Chris Lattner16fb0032005-02-19 02:22:14 +0000[diff] [blame]811 href="#t_function">function</a> that takes an <tt>int*</tt>, returning an
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]812 <tt>int</tt>.<br/>
813 </td>
814 </tr>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]815</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]816</div>
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]817
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]818<!-- _______________________________________________________________________ -->
819<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]820<div class="doc_text">
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]821
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]822<h5>Overview:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]823
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]824<p>A packed type is a simple derived type that represents a vector
825of elements. Packed types are used when multiple primitive data
826are operated in parallel using a single instruction (SIMD).
827A packed type requires a size (number of
828elements) and an underlying primitive data type. Packed types are
829considered <a href="#t_firstclass">first class</a>.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]830
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]831<h5>Syntax:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]832
833<pre>
834 &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
835</pre>
836
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]837<p>The number of elements is a constant integer value, elementtype may
838be any integral or floating point type.</p>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]839
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]840<h5>Examples:</h5>
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]841
Reid Spencerc3c4c4f2004-11-01 08:19:36 +0000[diff] [blame]842<table class="layout">
843 <tr class="layout">
844 <td class="left">
845 <tt>&lt;4 x int&gt;</tt><br/>
846 <tt>&lt;8 x float&gt;</tt><br/>
847 <tt>&lt;2 x uint&gt;</tt><br/>
848 </td>
849 <td class="left">
850 Packed vector of 4 integer values.<br/>
851 Packed vector of 8 floating-point values.<br/>
852 Packed vector of 2 unsigned integer values.<br/>
853 </td>
854 </tr>
855</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]856</div>
857
Chris Lattner37b6b092005-04-25 17:34:15 +0000[diff] [blame]858<!-- _______________________________________________________________________ -->
859<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
860<div class="doc_text">
861
862<h5>Overview:</h5>
863
864<p>Opaque types are used to represent unknown types in the system. This
865corresponds (for example) to the C notion of a foward declared structure type.
866In LLVM, opaque types can eventually be resolved to any type (not just a
867structure type).</p>
868
869<h5>Syntax:</h5>
870
871<pre>
872 opaque
873</pre>
874
875<h5>Examples:</h5>
876
877<table class="layout">
878 <tr class="layout">
879 <td class="left">
880 <tt>opaque</tt>
881 </td>
882 <td class="left">
883 An opaque type.<br/>
884 </td>
885 </tr>
886</table>
887</div>
888
889
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]890<!-- *********************************************************************** -->
891<div class="doc_section"> <a name="constants">Constants</a> </div>
892<!-- *********************************************************************** -->
893
894<div class="doc_text">
895
896<p>LLVM has several different basic types of constants. This section describes
897them all and their syntax.</p>
898
899</div>
900
901<!-- ======================================================================= -->
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]902<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]903
904<div class="doc_text">
905
906<dl>
907 <dt><b>Boolean constants</b></dt>
908
909 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
910 constants of the <tt><a href="#t_primitive">bool</a></tt> type.
911 </dd>
912
913 <dt><b>Integer constants</b></dt>
914
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]915 <dd>Standard integers (such as '4') are constants of the <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]916 href="#t_integer">integer</a> type. Negative numbers may be used with signed
917 integer types.
918 </dd>
919
920 <dt><b>Floating point constants</b></dt>
921
922 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
923 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]924 notation. Floating point constants have an optional hexadecimal
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]925 notation (see below). Floating point constants must have a <a
926 href="#t_floating">floating point</a> type. </dd>
927
928 <dt><b>Null pointer constants</b></dt>
929
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]930 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]931 and must be of <a href="#t_pointer">pointer type</a>.</dd>
932
933</dl>
934
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]935<p>The one non-intuitive notation for constants is the optional hexadecimal form
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]936of floating point constants. For example, the form '<tt>double
9370x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
9384.5e+15</tt>'. The only time hexadecimal floating point constants are required
Reid Spencer8f08d802004-12-09 18:02:53 +0000[diff] [blame]939(and the only time that they are generated by the disassembler) is when a
940floating point constant must be emitted but it cannot be represented as a
941decimal floating point number. For example, NaN's, infinities, and other
942special values are represented in their IEEE hexadecimal format so that
943assembly and disassembly do not cause any bits to change in the constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]944
945</div>
946
947<!-- ======================================================================= -->
948<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
949</div>
950
951<div class="doc_text">
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]952<p>Aggregate constants arise from aggregation of simple constants
953and smaller aggregate constants.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]954
955<dl>
956 <dt><b>Structure constants</b></dt>
957
958 <dd>Structure constants are represented with notation similar to structure
959 type definitions (a comma separated list of elements, surrounded by braces
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]960 (<tt>{}</tt>)). For example: "<tt>{ int 4, float 17.0, int* %G }</tt>",
961 where "<tt>%G</tt>" is declared as "<tt>%G = external global int</tt>". Structure constants
962 must have <a href="#t_struct">structure type</a>, and the number and
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]963 types of elements must match those specified by the type.
964 </dd>
965
966 <dt><b>Array constants</b></dt>
967
968 <dd>Array constants are represented with notation similar to array type
969 definitions (a comma separated list of elements, surrounded by square brackets
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]970 (<tt>[]</tt>)). For example: "<tt>[ int 42, int 11, int 74 ]</tt>". Array
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]971 constants must have <a href="#t_array">array type</a>, and the number and
972 types of elements must match those specified by the type.
973 </dd>
974
975 <dt><b>Packed constants</b></dt>
976
977 <dd>Packed constants are represented with notation similar to packed type
978 definitions (a comma separated list of elements, surrounded by
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]979 less-than/greater-than's (<tt>&lt;&gt;</tt>)). For example: "<tt>&lt; int 42,
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]980 int 11, int 74, int 100 &gt;</tt>". Packed constants must have <a
981 href="#t_packed">packed type</a>, and the number and types of elements must
982 match those specified by the type.
983 </dd>
984
985 <dt><b>Zero initialization</b></dt>
986
987 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
988 value to zero of <em>any</em> type, including scalar and aggregate types.
989 This is often used to avoid having to print large zero initializers (e.g. for
990 large arrays), and is always exactly equivalent to using explicit zero
991 initializers.
992 </dd>
993</dl>
994
995</div>
996
997<!-- ======================================================================= -->
998<div class="doc_subsection">
999 <a name="globalconstants">Global Variable and Function Addresses</a>
1000</div>
1001
1002<div class="doc_text">
1003
1004<p>The addresses of <a href="#globalvars">global variables</a> and <a
1005href="#functionstructure">functions</a> are always implicitly valid (link-time)
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1006constants. These constants are explicitly referenced when the <a
1007href="#identifiers">identifier for the global</a> is used and always have <a
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1008href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1009file:</p>
1010
1011<pre>
1012 %X = global int 17
1013 %Y = global int 42
1014 %Z = global [2 x int*] [ int* %X, int* %Y ]
1015</pre>
1016
1017</div>
1018
1019<!-- ======================================================================= -->
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1020<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1021<div class="doc_text">
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1022 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1023 no specific value. Undefined values may be of any type, and be used anywhere
1024 a constant is permitted.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1025
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1026 <p>Undefined values indicate to the compiler that the program is well defined
1027 no matter what value is used, giving the compiler more freedom to optimize.
1028 </p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1029</div>
1030
1031<!-- ======================================================================= -->
1032<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1033</div>
1034
1035<div class="doc_text">
1036
1037<p>Constant expressions are used to allow expressions involving other constants
1038to be used as constants. Constant expressions may be of any <a
1039href="#t_firstclass">first class</a> type, and may involve any LLVM operation
1040that does not have side effects (e.g. load and call are not supported). The
1041following is the syntax for constant expressions:</p>
1042
1043<dl>
1044 <dt><b><tt>cast ( CST to TYPE )</tt></b></dt>
1045
1046 <dd>Cast a constant to another type.</dd>
1047
1048 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1049
1050 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1051 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1052 instruction, the index list may have zero or more indexes, which are required
1053 to make sense for the type of "CSTPTR".</dd>
1054
1055 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1056
Reid Spencer641f5c92004-12-09 18:13:12 +0000[diff] [blame]1057 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1058 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1059 binary</a> operations. The constraints on operands are the same as those for
1060 the corresponding instruction (e.g. no bitwise operations on floating point
1061 are allowed).</dd>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1062</dl>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1063</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]1064
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1065<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1066<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1067<!-- *********************************************************************** -->
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1068
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1069<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1070
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1071<p>The LLVM instruction set consists of several different
1072classifications of instructions: <a href="#terminators">terminator
1073instructions</a>, <a href="#binaryops">binary instructions</a>, <a
1074 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1075instructions</a>.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1076
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1077</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1078
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1079<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1080<div class="doc_subsection"> <a name="terminators">Terminator
1081Instructions</a> </div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1082
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1083<div class="doc_text">
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1084
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1085<p>As mentioned <a href="#functionstructure">previously</a>, every
1086basic block in a program ends with a "Terminator" instruction, which
1087indicates which block should be executed after the current block is
1088finished. These terminator instructions typically yield a '<tt>void</tt>'
1089value: they produce control flow, not values (the one exception being
1090the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1091<p>There are six different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1092 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1093instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1094the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1095 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1096 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1097
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1098</div>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]1099
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1100<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1101<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1102Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1103<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1104<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1105<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]1106 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1107</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1108<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1109<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1110value) from a function, back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1111<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1112returns a value and then causes control flow, and one that just causes
1113control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1114<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1115<p>The '<tt>ret</tt>' instruction may return any '<a
1116 href="#t_firstclass">first class</a>' type. Notice that a function is
1117not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
1118instruction inside of the function that returns a value that does not
1119match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1120<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1121<p>When the '<tt>ret</tt>' instruction is executed, control flow
1122returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]1123 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1124the instruction after the call. If the caller was an "<a
1125 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1126at the beginning "normal" of the destination block. If the instruction
1127returns a value, that value shall set the call or invoke instruction's
1128return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1129<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1130<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1131 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1132</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1133</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1134<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1135<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1136<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1137<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1138<pre> br bool &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br> br label &lt;dest&gt; <i>; Unconditional branch</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1139</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1140<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1141<p>The '<tt>br</tt>' instruction is used to cause control flow to
1142transfer to a different basic block in the current function. There are
1143two forms of this instruction, corresponding to a conditional branch
1144and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1145<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1146<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1147single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
1148unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
1149value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1150<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1151<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
1152argument is evaluated. If the value is <tt>true</tt>, control flows
1153to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1154control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1155<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1156<pre>Test:<br> %cond = <a href="#i_setcc">seteq</a> int %a, %b<br> br bool %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
1157 href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1158</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1159<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1160<div class="doc_subsubsection">
1161 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1162</div>
1163
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1164<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1165<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1166
1167<pre>
1168 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
1169</pre>
1170
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1171<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1172
1173<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1174several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1175instruction, allowing a branch to occur to one of many possible
1176destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1177
1178
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1179<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1180
1181<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1182comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1183an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1184table is not allowed to contain duplicate constant entries.</p>
1185
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1186<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1187
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1188<p>The <tt>switch</tt> instruction specifies a table of values and
1189destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1190table is searched for the given value. If the value is found, control flow is
1191transfered to the corresponding destination; otherwise, control flow is
1192transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1193
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1194<h5>Implementation:</h5>
1195
1196<p>Depending on properties of the target machine and the particular
1197<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]1198ways. For example, it could be generated as a series of chained conditional
1199branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]1200
1201<h5>Example:</h5>
1202
1203<pre>
1204 <i>; Emulate a conditional br instruction</i>
1205 %Val = <a href="#i_cast">cast</a> bool %value to int
1206 switch int %Val, label %truedest [int 0, label %falsedest ]
1207
1208 <i>; Emulate an unconditional br instruction</i>
1209 switch uint 0, label %dest [ ]
1210
1211 <i>; Implement a jump table:</i>
1212 switch uint %val, label %otherwise [ uint 0, label %onzero
1213 uint 1, label %onone
1214 uint 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1215</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1216</div>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1217
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1218<!-- _______________________________________________________________________ -->
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1219<div class="doc_subsubsection">
1220 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
1221</div>
1222
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1223<div class="doc_text">
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1224
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1225<h5>Syntax:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1226
1227<pre>
1228 &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
1229 to label &lt;normal label&gt; except label &lt;exception label&gt;
1230</pre>
1231
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1232<h5>Overview:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1233
1234<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
1235function, with the possibility of control flow transfer to either the
1236'<tt>normal</tt>' <tt>label</tt> label or the
1237'<tt>exception</tt>'<tt>label</tt>. If the callee function returns with the
1238"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
1239"normal" label. If the callee (or any indirect callees) returns with the "<a
1240href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted, and
1241continued at the dynamically nearest "except" label.</p>
1242
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1243<h5>Arguments:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1244
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1245<p>This instruction requires several arguments:</p>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1246
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1247<ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1248 <li>
1249 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
1250 convention</a> the call should use. If none is specified, the call defaults
1251 to using C calling conventions.
1252 </li>
1253 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
1254 function value being invoked. In most cases, this is a direct function
1255 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
1256 an arbitrary pointer to function value.
1257 </li>
1258
1259 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
1260 function to be invoked. </li>
1261
1262 <li>'<tt>function args</tt>': argument list whose types match the function
1263 signature argument types. If the function signature indicates the function
1264 accepts a variable number of arguments, the extra arguments can be
1265 specified. </li>
1266
1267 <li>'<tt>normal label</tt>': the label reached when the called function
1268 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
1269
1270 <li>'<tt>exception label</tt>': the label reached when a callee returns with
1271 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
1272
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1273</ol>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1274
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1275<h5>Semantics:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1276
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1277<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1278href="#i_call">call</a></tt>' instruction in most regards. The primary
1279difference is that it establishes an association with a label, which is used by
1280the runtime library to unwind the stack.</p>
1281
1282<p>This instruction is used in languages with destructors to ensure that proper
1283cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
1284exception. Additionally, this is important for implementation of
1285'<tt>catch</tt>' clauses in high-level languages that support them.</p>
1286
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1287<h5>Example:</h5>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]1288<pre>
1289 %retval = invoke int %Test(int 15) to label %Continue
1290 except label %TestCleanup <i>; {int}:retval set</i>
1291 %retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
1292 except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1293</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1294</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1295
1296
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1297<!-- _______________________________________________________________________ -->
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1298
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1299<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
1300Instruction</a> </div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1301
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1302<div class="doc_text">
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1303
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1304<h5>Syntax:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1305<pre>
1306 unwind
1307</pre>
1308
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1309<h5>Overview:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1310
1311<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
1312at the first callee in the dynamic call stack which used an <a
1313href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
1314primarily used to implement exception handling.</p>
1315
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1316<h5>Semantics:</h5>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1317
1318<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
1319immediately halt. The dynamic call stack is then searched for the first <a
1320href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
1321execution continues at the "exceptional" destination block specified by the
1322<tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
1323dynamic call chain, undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1324</div>
Chris Lattner08b7d5b2004-10-16 18:04:13 +0000[diff] [blame]1325
1326<!-- _______________________________________________________________________ -->
1327
1328<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
1329Instruction</a> </div>
1330
1331<div class="doc_text">
1332
1333<h5>Syntax:</h5>
1334<pre>
1335 unreachable
1336</pre>
1337
1338<h5>Overview:</h5>
1339
1340<p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
1341instruction is used to inform the optimizer that a particular portion of the
1342code is not reachable. This can be used to indicate that the code after a
1343no-return function cannot be reached, and other facts.</p>
1344
1345<h5>Semantics:</h5>
1346
1347<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
1348</div>
1349
1350
1351
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1352<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1353<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1354<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1355<p>Binary operators are used to do most of the computation in a
1356program. They require two operands, execute an operation on them, and
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1357produce a single value. The operands might represent
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1358multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
1359The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1360necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1361<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1362</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1363<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1364<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
1365Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1366<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1367<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1368<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]1369</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1370<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1371<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1372<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1373<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1374 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
1375 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1376Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1377<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1378<p>The value produced is the integer or floating point sum of the two
1379operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1380<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1381<pre> &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1382</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1383</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1384<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1385<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
1386Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1387<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1388<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1389<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]1390</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1391<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1392<p>The '<tt>sub</tt>' instruction returns the difference of its two
1393operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1394<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
1395instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1396<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1397<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1398 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1399values.
1400This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1401Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1402<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1403<p>The value produced is the integer or floating point difference of
1404the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1405<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1406<pre> &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1407 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
1408</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1409</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1410<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1411<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1412Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1413<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1414<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1415<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]1416</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1417<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1418<p>The '<tt>mul</tt>' instruction returns the product of its two
1419operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1420<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1421<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1422 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1423values.
1424This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1425Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1426<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1427<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1428two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1429<p>There is no signed vs unsigned multiplication. The appropriate
1430action is taken based on the type of the operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1431<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1432<pre> &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1433</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1434</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1435<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1436<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1437Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1438<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1439<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1440<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1441</pre>
1442<h5>Overview:</h5>
1443<p>The '<tt>div</tt>' instruction returns the quotient of its two
1444operands.</p>
1445<h5>Arguments:</h5>
1446<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1447 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1448values.
1449This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1450Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1451<h5>Semantics:</h5>
1452<p>The value produced is the integer or floating point quotient of the
1453two operands.</p>
1454<h5>Example:</h5>
1455<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1456</pre>
1457</div>
1458<!-- _______________________________________________________________________ -->
1459<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1460Instruction</a> </div>
1461<div class="doc_text">
1462<h5>Syntax:</h5>
1463<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1464</pre>
1465<h5>Overview:</h5>
1466<p>The '<tt>rem</tt>' instruction returns the remainder from the
1467division of its two operands.</p>
1468<h5>Arguments:</h5>
1469<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1470 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1471values.
1472This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1473Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1474<h5>Semantics:</h5>
1475<p>This returns the <i>remainder</i> of a division (where the result
1476has the same sign as the divisor), not the <i>modulus</i> (where the
1477result has the same sign as the dividend) of a value. For more
1478information about the difference, see: <a
1479 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1480Math Forum</a>.</p>
1481<h5>Example:</h5>
1482<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1483</pre>
1484</div>
1485<!-- _______________________________________________________________________ -->
1486<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1487Instructions</a> </div>
1488<div class="doc_text">
1489<h5>Syntax:</h5>
1490<pre> &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1491 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1492 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1493 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1494 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1495 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1496</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1497<h5>Overview:</h5>
1498<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1499value based on a comparison of their two operands.</p>
1500<h5>Arguments:</h5>
1501<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1502be of <a href="#t_firstclass">first class</a> type (it is not possible
1503to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1504or '<tt>void</tt>' values, etc...). Both arguments must have identical
1505types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1506<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1507<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1508value if both operands are equal.<br>
1509The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1510value if both operands are unequal.<br>
1511The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1512value if the first operand is less than the second operand.<br>
1513The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1514value if the first operand is greater than the second operand.<br>
1515The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1516value if the first operand is less than or equal to the second operand.<br>
1517The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1518value if the first operand is greater than or equal to the second
1519operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1520<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1521<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1522 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1523 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1524 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1525 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1526 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1527</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1528</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1529<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1530<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1531Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1532<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1533<p>Bitwise binary operators are used to do various forms of
1534bit-twiddling in a program. They are generally very efficient
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1535instructions and can commonly be strength reduced from other
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1536instructions. They require two operands, execute an operation on them,
1537and produce a single value. The resulting value of the bitwise binary
1538operators is always the same type as its first operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1539</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1540<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1541<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1542Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1543<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1544<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1545<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]1546</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1547<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1548<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1549its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1550<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1551<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1552 href="#t_integral">integral</a> values. Both arguments must have
1553identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1554<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1555<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1556<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1557<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1558<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1559 <tbody>
1560 <tr>
1561 <td>In0</td>
1562 <td>In1</td>
1563 <td>Out</td>
1564 </tr>
1565 <tr>
1566 <td>0</td>
1567 <td>0</td>
1568 <td>0</td>
1569 </tr>
1570 <tr>
1571 <td>0</td>
1572 <td>1</td>
1573 <td>0</td>
1574 </tr>
1575 <tr>
1576 <td>1</td>
1577 <td>0</td>
1578 <td>0</td>
1579 </tr>
1580 <tr>
1581 <td>1</td>
1582 <td>1</td>
1583 <td>1</td>
1584 </tr>
1585 </tbody>
1586</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1587</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1588<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1589<pre> &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 &amp; %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1590 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1591 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1592</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1593</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1594<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1595<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1596<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1597<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1598<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]1599</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1600<h5>Overview:</h5>
1601<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1602or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1603<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1604<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1605 href="#t_integral">integral</a> values. Both arguments must have
1606identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1607<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1608<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1609<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1610<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1611<table border="1" cellspacing="0" cellpadding="4">
1612 <tbody>
1613 <tr>
1614 <td>In0</td>
1615 <td>In1</td>
1616 <td>Out</td>
1617 </tr>
1618 <tr>
1619 <td>0</td>
1620 <td>0</td>
1621 <td>0</td>
1622 </tr>
1623 <tr>
1624 <td>0</td>
1625 <td>1</td>
1626 <td>1</td>
1627 </tr>
1628 <tr>
1629 <td>1</td>
1630 <td>0</td>
1631 <td>1</td>
1632 </tr>
1633 <tr>
1634 <td>1</td>
1635 <td>1</td>
1636 <td>1</td>
1637 </tr>
1638 </tbody>
1639</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1640</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1641<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1642<pre> &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1643 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1644 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1645</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1646</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1647<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1648<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1649Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1650<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1651<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1652<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]1653</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1654<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1655<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1656or of its two operands. The <tt>xor</tt> is used to implement the
1657"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1658<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1659<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1660 href="#t_integral">integral</a> values. Both arguments must have
1661identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1662<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1663<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1664<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1665<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1666<table border="1" cellspacing="0" cellpadding="4">
1667 <tbody>
1668 <tr>
1669 <td>In0</td>
1670 <td>In1</td>
1671 <td>Out</td>
1672 </tr>
1673 <tr>
1674 <td>0</td>
1675 <td>0</td>
1676 <td>0</td>
1677 </tr>
1678 <tr>
1679 <td>0</td>
1680 <td>1</td>
1681 <td>1</td>
1682 </tr>
1683 <tr>
1684 <td>1</td>
1685 <td>0</td>
1686 <td>1</td>
1687 </tr>
1688 <tr>
1689 <td>1</td>
1690 <td>1</td>
1691 <td>0</td>
1692 </tr>
1693 </tbody>
1694</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1695</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1696<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1697<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1698<pre> &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1699 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1700 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1701 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1702</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1703</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1704<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1705<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1706Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1707<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1708<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1709<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1710</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1711<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1712<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1713the left a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1714<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1715<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1716 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1717type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1718<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1719<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]1720<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1721<pre> &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 &lt;&lt; %var</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1722 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1723 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1724</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1725</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1726<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1727<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1728Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1729<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1730<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1731<pre> &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1732</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1733<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1734<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1735the right a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1736<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1737<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1738 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1739type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1740<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1741<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1742most significant bit is duplicated in the newly free'd bit positions.
1743If the first argument is unsigned, zero bits shall fill the empty
1744positions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1745<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1746<pre> &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 &gt;&gt; %var</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1747 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1748 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1749 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1750 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1751</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1752</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1753<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1754<div class="doc_subsection"> <a name="memoryops">Memory Access
1755Operations</a></div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1756<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1757<p>A key design point of an SSA-based representation is how it
1758represents memory. In LLVM, no memory locations are in SSA form, which
1759makes things very simple. This section describes how to read, write,
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1760allocate, and free memory in LLVM.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1761</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1762<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1763<div class="doc_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>'
1764Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1765<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1766<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1767<pre> &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1768 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1769</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1770<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1771<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1772heap and returns a pointer to it.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1773<h5>Arguments:</h5>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]1774<p>The '<tt>malloc</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1775bytes of memory from the operating system and returns a pointer of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1776appropriate type to the program. The second form of the instruction is
1777a shorter version of the first instruction that defaults to allocating
1778one element.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1779<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1780<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1781<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1782a pointer is returned.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1783<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1784<pre> %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1785
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1786 %size = <a
1787 href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1788 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1789 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1790</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1791</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1792<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1793<div class="doc_subsubsection"> <a name="i_free">'<tt>free</tt>'
1794Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1795<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1796<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1797<pre> free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1798</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1799<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1800<p>The '<tt>free</tt>' instruction returns memory back to the unused
1801memory heap, to be reallocated in the future.</p>
1802<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1803<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1804<p>'<tt>value</tt>' shall be a pointer value that points to a value
1805that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1806instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1807<h5>Semantics:</h5>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1808<p>Access to the memory pointed to by the pointer is no longer defined
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1809after this instruction executes.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1810<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1811<pre> %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1812 free [4 x ubyte]* %array
1813</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1814</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1815<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1816<div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>'
1817Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1818<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1819<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1820<pre> &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1821 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1822</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1823<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1824<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1825stack frame of the procedure that is live until the current function
1826returns to its caller.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1827<h5>Arguments:</h5>
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]1828<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1829bytes of memory on the runtime stack, returning a pointer of the
1830appropriate type to the program. The second form of the instruction is
1831a shorter version of the first that defaults to allocating one element.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1832<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1833<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1834<p>Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d
1835memory is automatically released when the function returns. The '<tt>alloca</tt>'
1836instruction is commonly used to represent automatic variables that must
1837have an address available. When the function returns (either with the <tt><a
1838 href="#i_ret">ret</a></tt> or <tt><a href="#i_invoke">invoke</a></tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1839instructions), the memory is reclaimed.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1840<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1841<pre> %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1842 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1843</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1844</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1845<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1846<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1847Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1848<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1849<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1850<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]1851<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1852<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1853<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1854<p>The argument to the '<tt>load</tt>' instruction specifies the memory
1855address to load from. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1856 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1857marked as <tt>volatile</tt> then the optimizer is not allowed to modify
1858the number or order of execution of this <tt>load</tt> with other
1859volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1860instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1861<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1862<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1863<h5>Examples:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1864<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1865 <a
1866 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1867 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1868</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1869</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1870<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1871<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1872Instruction</a> </div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1873<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1874<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]1875 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]1876</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1877<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1878<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1879<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1880<p>There are two arguments to the '<tt>store</tt>' instruction: a value
1881to store and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1882operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
1883operand. If the <tt>store</tt> is marked as <tt>volatile</tt> then the
1884optimizer is not allowed to modify the number or order of execution of
1885this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1886 href="#i_store">store</a></tt> instructions.</p>
1887<h5>Semantics:</h5>
1888<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1889at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1890<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1891<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1892 <a
1893 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1894 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1895</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1896<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1897<div class="doc_subsubsection">
1898 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
1899</div>
1900
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1901<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1902<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1903<pre>
1904 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
1905</pre>
1906
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1907<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1908
1909<p>
1910The '<tt>getelementptr</tt>' instruction is used to get the address of a
1911subelement of an aggregate data structure.</p>
1912
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1913<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1914
1915<p>This instruction takes a list of integer constants that indicate what
1916elements of the aggregate object to index to. The actual types of the arguments
1917provided depend on the type of the first pointer argument. The
1918'<tt>getelementptr</tt>' instruction is used to index down through the type
1919levels of a structure. When indexing into a structure, only <tt>uint</tt>
1920integer constants are allowed. When indexing into an array or pointer
1921<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
1922
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1923<p>For example, let's consider a C code fragment and how it gets
1924compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1925
1926<pre>
1927 struct RT {
1928 char A;
1929 int B[10][20];
1930 char C;
1931 };
1932 struct ST {
1933 int X;
1934 double Y;
1935 struct RT Z;
1936 };
1937
1938 int *foo(struct ST *s) {
1939 return &amp;s[1].Z.B[5][13];
1940 }
1941</pre>
1942
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1943<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1944
1945<pre>
1946 %RT = type { sbyte, [10 x [20 x int]], sbyte }
1947 %ST = type { int, double, %RT }
1948
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]1949 implementation
1950
1951 int* %foo(%ST* %s) {
1952 entry:
1953 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1954 ret int* %reg
1955 }
1956</pre>
1957
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1958<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1959
1960<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1961on the pointer type that is being index into. <a href="#t_pointer">Pointer</a>
1962and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
1963<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1964types require <tt>uint</tt> <b>constants</b>.</p>
1965
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1966<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1967type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
1968}</tt>' type, a structure. The second index indexes into the third element of
1969the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
1970sbyte }</tt>' type, another structure. The third index indexes into the second
1971element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
1972array. The two dimensions of the array are subscripted into, yielding an
1973'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction return a pointer
1974to this element, thus computing a value of '<tt>int*</tt>' type.</p>
1975
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1976<p>Note that it is perfectly legal to index partially through a
1977structure, returning a pointer to an inner element. Because of this,
1978the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1979
1980<pre>
Chris Lattner455fc8c2005-03-07 22:13:59 +0000[diff] [blame]1981 int* %foo(%ST* %s) {
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1982 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
1983 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
1984 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1985 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
1986 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
1987 ret int* %t5
1988 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1989</pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1990<h5>Example:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1991<pre>
1992 <i>; yields [12 x ubyte]*:aptr</i>
1993 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
1994</pre>
1995
1996</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1997<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1998<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1999<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]2000<p>The instructions in this category are the "miscellaneous"
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2001instructions, which defy better classification.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2002</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2003<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2004<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
2005Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2006<div class="doc_text">
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2007<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2008<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2009<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2010<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
2011the SSA graph representing the function.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2012<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2013<p>The type of the incoming values are specified with the first type
2014field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
2015as arguments, with one pair for each predecessor basic block of the
2016current block. Only values of <a href="#t_firstclass">first class</a>
2017type may be used as the value arguments to the PHI node. Only labels
2018may be used as the label arguments.</p>
2019<p>There must be no non-phi instructions between the start of a basic
2020block and the PHI instructions: i.e. PHI instructions must be first in
2021a basic block.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2022<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2023<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
2024value specified by the parameter, depending on which basic block we
2025came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2026<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2027<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2028</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2029
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2030<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2031<div class="doc_subsubsection">
2032 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
2033</div>
2034
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2035<div class="doc_text">
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2036
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2037<h5>Syntax:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2038
2039<pre>
2040 &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2041</pre>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2042
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2043<h5>Overview:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2044
2045<p>
2046The '<tt>cast</tt>' instruction is used as the primitive means to convert
2047integers to floating point, change data type sizes, and break type safety (by
2048casting pointers).
2049</p>
2050
2051
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2052<h5>Arguments:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2053
2054<p>
2055The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
2056class value, and a type to cast it to, which must also be a <a
2057href="#t_firstclass">first class</a> type.
2058</p>
2059
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2060<h5>Semantics:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2061
2062<p>
2063This instruction follows the C rules for explicit casts when determining how the
2064data being cast must change to fit in its new container.
2065</p>
2066
2067<p>
2068When casting to bool, any value that would be considered true in the context of
2069a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
2070all else are '<tt>false</tt>'.
2071</p>
2072
2073<p>
2074When extending an integral value from a type of one signness to another (for
2075example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
2076<b>source</b> value is signed, and zero-extended if the source value is
2077unsigned. <tt>bool</tt> values are always zero extended into either zero or
2078one.
2079</p>
2080
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2081<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2082
2083<pre>
2084 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattnerd8f8ede2002-06-25 18:03:17 +0000[diff] [blame]2085 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2086</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2087</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]2088
2089<!-- _______________________________________________________________________ -->
2090<div class="doc_subsubsection">
2091 <a name="i_select">'<tt>select</tt>' Instruction</a>
2092</div>
2093
2094<div class="doc_text">
2095
2096<h5>Syntax:</h5>
2097
2098<pre>
2099 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
2100</pre>
2101
2102<h5>Overview:</h5>
2103
2104<p>
2105The '<tt>select</tt>' instruction is used to choose one value based on a
2106condition, without branching.
2107</p>
2108
2109
2110<h5>Arguments:</h5>
2111
2112<p>
2113The '<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.
2114</p>
2115
2116<h5>Semantics:</h5>
2117
2118<p>
2119If the boolean condition evaluates to true, the instruction returns the first
2120value argument, otherwise it returns the second value argument.
2121</p>
2122
2123<h5>Example:</h5>
2124
2125<pre>
2126 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
2127</pre>
2128</div>
2129
2130
2131
2132
2133
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]2134<!-- _______________________________________________________________________ -->
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2135<div class="doc_subsubsection">
2136 <a name="i_call">'<tt>call</tt>' Instruction</a>
2137</div>
2138
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2139<div class="doc_text">
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2140
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2141<h5>Syntax:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2142<pre>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]2143 &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]2144</pre>
2145
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2146<h5>Overview:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2147
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2148<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2149
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2150<h5>Arguments:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2151
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2152<p>This instruction requires several arguments:</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2153
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2154<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2155 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]2156 <p>The optional "tail" marker indicates whether the callee function accesses
2157 any allocas or varargs in the caller. If the "tail" marker is present, the
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2158 function call is eligible for tail call optimization. Note that calls may
2159 be marked "tail" even if they do not occur before a <a
2160 href="#i_ret"><tt>ret</tt></a> instruction.
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2161 </li>
2162 <li>
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]2163 <p>The optional "cconv" marker indicates which <a href="callingconv">calling
2164 convention</a> the call should use. If none is specified, the call defaults
2165 to using C calling conventions.
2166 </li>
2167 <li>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2168 <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
2169 being invoked. The argument types must match the types implied by this
2170 signature.</p>
2171 </li>
2172 <li>
2173 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
2174 be invoked. In most cases, this is a direct function invocation, but
2175 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
2176 to function values.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2177 </li>
2178 <li>
2179 <p>'<tt>function args</tt>': argument list whose types match the
Reid Spencerd845d162005-05-01 22:22:57 +0000[diff] [blame]2180 function signature argument types. All arguments must be of
2181 <a href="#t_firstclass">first class</a> type. If the function signature
2182 indicates the function accepts a variable number of arguments, the extra
2183 arguments can be specified.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2184 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]2185</ol>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2186
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2187<h5>Semantics:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2188
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2189<p>The '<tt>call</tt>' instruction is used to cause control flow to
2190transfer to a specified function, with its incoming arguments bound to
2191the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
2192instruction in the called function, control flow continues with the
2193instruction after the function call, and the return value of the
2194function is bound to the result argument. This is a simpler case of
2195the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2196
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2197<h5>Example:</h5>
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2198
2199<pre>
2200 %retval = call int %test(int %argc)
2201 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
2202 %X = tail call int %foo()
Chris Lattner0132aff2005-05-06 22:57:40 +0000[diff] [blame^]2203 %Y = tail call <a href="#callingconv">fastcc</a> int %foo()
Chris Lattnere23c1392005-05-06 05:47:36 +0000[diff] [blame]2204</pre>
2205
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2206</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2207
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2208<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2209<div class="doc_subsubsection">
2210 <a name="i_vanext">'<tt>vanext</tt>' Instruction</a>
2211</div>
2212
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2213<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2214
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2215<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2216
2217<pre>
2218 &lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
2219</pre>
2220
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2221<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2222
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2223<p>The '<tt>vanext</tt>' instruction is used to access arguments passed
2224through the "variable argument" area of a function call. It is used to
2225implement the <tt>va_arg</tt> macro in C.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2226
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2227<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2228
2229<p>This instruction takes a <tt>va_list</tt> value and the type of the
2230argument. It returns another <tt>va_list</tt>. The actual type of
2231<tt>va_list</tt> may be defined differently for different targets. Most targets
2232use a <tt>va_list</tt> type of <tt>sbyte*</tt> or some other pointer type.</p>
2233
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2234<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2235
2236<p>The '<tt>vanext</tt>' instruction advances the specified <tt>va_list</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2237past an argument of the specified type. In conjunction with the <a
2238 href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement
2239the <tt>va_arg</tt> macro available in C. For more information, see
2240the variable argument handling <a href="#int_varargs">Intrinsic
2241Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2242
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2243<p>It is legal for this instruction to be called in a function which
2244does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2245function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2246
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2247<p><tt>vanext</tt> is an LLVM instruction instead of an <a
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2248href="#intrinsics">intrinsic function</a> because it takes a type as an
2249argument. The type refers to the current argument in the <tt>va_list</tt>, it
2250tells the compiler how far on the stack it needs to advance to find the next
2251argument</p>
2252
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2253<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2254
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2255<p>See the <a href="#int_varargs">variable argument processing</a>
2256section.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2257
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2258</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2259
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2260<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2261<div class="doc_subsubsection">
2262 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
2263</div>
2264
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2265<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2266
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2267<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2268
2269<pre>
2270 &lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
2271</pre>
2272
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2273<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2274
2275<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed through
2276the "variable argument" area of a function call. It is used to implement the
2277<tt>va_arg</tt> macro in C.</p>
2278
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2279<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2280
2281<p>This instruction takes a <tt>va_list</tt> value and the type of the
2282argument. It returns a value of the specified argument type. Again, the actual
2283type of <tt>va_list</tt> is target specific.</p>
2284
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2285<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2286
2287<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified type from
2288the specified <tt>va_list</tt>. In conjunction with the <a
2289href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to implement the
2290<tt>va_arg</tt> macro available in C. For more information, see the variable
2291argument handling <a href="#int_varargs">Intrinsic Functions</a>.</p>
2292
2293<p>It is legal for this instruction to be called in a function which does not
2294take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2295function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2296
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2297<p><tt>vaarg</tt> is an LLVM instruction instead of an <a
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2298href="#intrinsics">intrinsic function</a> because it takes an type as an
2299argument.</p>
2300
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]2301<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame]2302
2303<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
2304
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2305</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2306
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2307<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2308<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
2309<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2310
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2311<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2312
2313<p>LLVM supports the notion of an "intrinsic function". These functions have
2314well known names and semantics, and are required to follow certain
2315restrictions. Overall, these instructions represent an extension mechanism for
2316the LLVM language that does not require changing all of the transformations in
2317LLVM to add to the language (or the bytecode reader/writer, the parser,
2318etc...).</p>
2319
2320<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix, this
2321prefix is reserved in LLVM for intrinsic names, thus functions may not be named
2322this. Intrinsic functions must always be external functions: you cannot define
2323the body of intrinsic functions. Intrinsic functions may only be used in call
2324or invoke instructions: it is illegal to take the address of an intrinsic
2325function. Additionally, because intrinsic functions are part of the LLVM
2326language, it is required that they all be documented here if any are added.</p>
2327
2328
2329<p>
2330Adding an intrinsic to LLVM is straight-forward if it is possible to express the
2331concept in LLVM directly (ie, code generator support is not _required_). To do
2332this, extend the default implementation of the IntrinsicLowering class to handle
2333the intrinsic. Code generators use this class to lower intrinsics they do not
2334understand to raw LLVM instructions that they do.
2335</p>
2336
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2337</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2338
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2339<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2340<div class="doc_subsection">
2341 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
2342</div>
2343
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2344<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2345
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2346<p>Variable argument support is defined in LLVM with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2347 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
2348intrinsic functions. These functions are related to the similarly
2349named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2350
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2351<p>All of these functions operate on arguments that use a
2352target-specific value type "<tt>va_list</tt>". The LLVM assembly
2353language reference manual does not define what this type is, so all
2354transformations should be prepared to handle intrinsics with any type
2355used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2356
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2357<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2358instruction and the variable argument handling intrinsic functions are
2359used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2360
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2361<pre>
2362int %test(int %X, ...) {
2363 ; Initialize variable argument processing
2364 %ap = call sbyte* %<a href="#i_va_start">llvm.va_start</a>()
2365
2366 ; Read a single integer argument
2367 %tmp = vaarg sbyte* %ap, int
2368
2369 ; Advance to the next argument
2370 %ap2 = vanext sbyte* %ap, int
2371
2372 ; Demonstrate usage of llvm.va_copy and llvm.va_end
2373 %aq = call sbyte* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)
2374 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq)
2375
2376 ; Stop processing of arguments.
2377 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)
2378 ret int %tmp
2379}
2380</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2381</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2382
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2383<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2384<div class="doc_subsubsection">
2385 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
2386</div>
2387
2388
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2389<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2390<h5>Syntax:</h5>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2391<pre> declare &lt;va_list&gt; %llvm.va_start()<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2392<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2393<p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
2394for subsequent use by the variable argument intrinsics.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2395<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2396<p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2397macro available in C. In a target-dependent way, it initializes and
2398returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt>
2399will produce the first variable argument passed to the function. Unlike
2400the C <tt>va_start</tt> macro, this intrinsic does not need to know the
2401last argument of the function, the compiler can figure that out.</p>
2402<p>Note that this intrinsic function is only legal to be called from
2403within the body of a variable argument function.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2404</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2405
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2406<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2407<div class="doc_subsubsection">
2408 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
2409</div>
2410
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2411<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2412<h5>Syntax:</h5>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2413<pre> declare void %llvm.va_end(&lt;va_list&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2414<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2415<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
2416which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
2417or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2418<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2419<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2420<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2421<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2422macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
2423Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
2424 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
2425with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2426</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2427
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2428<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2429<div class="doc_subsubsection">
2430 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
2431</div>
2432
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2433<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2434
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2435<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2436
2437<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2438 declare &lt;va_list&gt; %llvm.va_copy(&lt;va_list&gt; &lt;destarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2439</pre>
2440
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2441<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2442
2443<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
2444from the source argument list to the destination argument list.</p>
2445
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2446<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2447
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2448<p>The argument is the <tt>va_list</tt> to copy.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2449
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2450<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2451
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2452<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2453macro available in C. In a target-dependent way, it copies the source
2454<tt>va_list</tt> element into the returned list. This intrinsic is necessary
Chris Lattner53e5e2a2004-06-21 22:52:48 +0000[diff] [blame]2455because the <tt><a href="#i_va_start">llvm.va_start</a></tt> intrinsic may be
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2456arbitrarily complex and require memory allocation, for example.</p>
2457
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2458</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2459
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2460<!-- ======================================================================= -->
2461<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2462 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2463</div>
2464
2465<div class="doc_text">
2466
2467<p>
2468LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2469Collection</a> requires the implementation and generation of these intrinsics.
2470These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2471stack</a>, as well as garbage collector implementations that require <a
2472href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2473Front-ends for type-safe garbage collected languages should generate these
2474intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2475href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2476</p>
2477</div>
2478
2479<!-- _______________________________________________________________________ -->
2480<div class="doc_subsubsection">
2481 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2482</div>
2483
2484<div class="doc_text">
2485
2486<h5>Syntax:</h5>
2487
2488<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2489 declare void %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2490</pre>
2491
2492<h5>Overview:</h5>
2493
John Criswelldfe6a862004-12-10 15:51:16 +0000[diff] [blame]2494<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2495the code generator, and allows some metadata to be associated with it.</p>
2496
2497<h5>Arguments:</h5>
2498
2499<p>The first argument specifies the address of a stack object that contains the
2500root pointer. The second pointer (which must be either a constant or a global
2501value address) contains the meta-data to be associated with the root.</p>
2502
2503<h5>Semantics:</h5>
2504
2505<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2506location. At compile-time, the code generator generates information to allow
2507the runtime to find the pointer at GC safe points.
2508</p>
2509
2510</div>
2511
2512
2513<!-- _______________________________________________________________________ -->
2514<div class="doc_subsubsection">
2515 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2516</div>
2517
2518<div class="doc_text">
2519
2520<h5>Syntax:</h5>
2521
2522<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2523 declare sbyte* %llvm.gcread(sbyte** %Ptr)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2524</pre>
2525
2526<h5>Overview:</h5>
2527
2528<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2529locations, allowing garbage collector implementations that require read
2530barriers.</p>
2531
2532<h5>Arguments:</h5>
2533
2534<p>The argument is the address to read from, which should be an address
2535allocated from the garbage collector.</p>
2536
2537<h5>Semantics:</h5>
2538
2539<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2540instruction, but may be replaced with substantially more complex code by the
2541garbage collector runtime, as needed.</p>
2542
2543</div>
2544
2545
2546<!-- _______________________________________________________________________ -->
2547<div class="doc_subsubsection">
2548 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2549</div>
2550
2551<div class="doc_text">
2552
2553<h5>Syntax:</h5>
2554
2555<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2556 declare void %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2557</pre>
2558
2559<h5>Overview:</h5>
2560
2561<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2562locations, allowing garbage collector implementations that require write
2563barriers (such as generational or reference counting collectors).</p>
2564
2565<h5>Arguments:</h5>
2566
2567<p>The first argument is the reference to store, and the second is the heap
2568location to store to.</p>
2569
2570<h5>Semantics:</h5>
2571
2572<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2573instruction, but may be replaced with substantially more complex code by the
2574garbage collector runtime, as needed.</p>
2575
2576</div>
2577
2578
2579
2580<!-- ======================================================================= -->
2581<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2582 <a name="int_codegen">Code Generator Intrinsics</a>
2583</div>
2584
2585<div class="doc_text">
2586<p>
2587These intrinsics are provided by LLVM to expose special features that may only
2588be implemented with code generator support.
2589</p>
2590
2591</div>
2592
2593<!-- _______________________________________________________________________ -->
2594<div class="doc_subsubsection">
2595 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2596</div>
2597
2598<div class="doc_text">
2599
2600<h5>Syntax:</h5>
2601<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2602 declare void* %llvm.returnaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2603</pre>
2604
2605<h5>Overview:</h5>
2606
2607<p>
2608The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2609indicating the return address of the current function or one of its callers.
2610</p>
2611
2612<h5>Arguments:</h5>
2613
2614<p>
2615The argument to this intrinsic indicates which function to return the address
2616for. Zero indicates the calling function, one indicates its caller, etc. The
2617argument is <b>required</b> to be a constant integer value.
2618</p>
2619
2620<h5>Semantics:</h5>
2621
2622<p>
2623The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2624the return address of the specified call frame, or zero if it cannot be
2625identified. The value returned by this intrinsic is likely to be incorrect or 0
2626for arguments other than zero, so it should only be used for debugging purposes.
2627</p>
2628
2629<p>
2630Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]2631aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2632source-language caller.
2633</p>
2634</div>
2635
2636
2637<!-- _______________________________________________________________________ -->
2638<div class="doc_subsubsection">
2639 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2640</div>
2641
2642<div class="doc_text">
2643
2644<h5>Syntax:</h5>
2645<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2646 declare void* %llvm.frameaddress(uint &lt;level&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2647</pre>
2648
2649<h5>Overview:</h5>
2650
2651<p>
2652The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2653pointer value for the specified stack frame.
2654</p>
2655
2656<h5>Arguments:</h5>
2657
2658<p>
2659The argument to this intrinsic indicates which function to return the frame
2660pointer for. Zero indicates the calling function, one indicates its caller,
2661etc. The argument is <b>required</b> to be a constant integer value.
2662</p>
2663
2664<h5>Semantics:</h5>
2665
2666<p>
2667The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2668the frame address of the specified call frame, or zero if it cannot be
2669identified. The value returned by this intrinsic is likely to be incorrect or 0
2670for arguments other than zero, so it should only be used for debugging purposes.
2671</p>
2672
2673<p>
2674Note that calling this intrinsic does not prevent function inlining or other
Chris Lattner2e6eb5f2005-03-07 20:30:51 +0000[diff] [blame]2675aggressive transformations, so the value returned may not be that of the obvious
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2676source-language caller.
2677</p>
2678</div>
2679
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2680<!-- _______________________________________________________________________ -->
2681<div class="doc_subsubsection">
2682 <a name="i_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
2683</div>
2684
2685<div class="doc_text">
2686
2687<h5>Syntax:</h5>
2688<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2689 declare void %llvm.prefetch(sbyte * &lt;address&gt;,
2690 uint &lt;rw&gt;, uint &lt;locality&gt;)
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2691</pre>
2692
2693<h5>Overview:</h5>
2694
2695
2696<p>
2697The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
2698a prefetch instruction if supported, otherwise it is a noop. Prefetches have no
Chris Lattnerff851072005-02-28 19:47:14 +0000[diff] [blame]2699effect on the behavior of the program, but can change its performance
2700characteristics.
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2701</p>
2702
2703<h5>Arguments:</h5>
2704
2705<p>
2706<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
2707determining if the fetch should be for a read (0) or write (1), and
2708<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
Chris Lattnerd3e641c2005-03-07 20:31:38 +0000[diff] [blame]2709locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2710<tt>locality</tt> arguments must be constant integers.
2711</p>
2712
2713<h5>Semantics:</h5>
2714
2715<p>
2716This intrinsic does not modify the behavior of the program. In particular,
2717prefetches cannot trap and do not produce a value. On targets that support this
2718intrinsic, the prefetch can provide hints to the processor cache for better
2719performance.
2720</p>
2721
2722</div>
2723
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2724<!-- _______________________________________________________________________ -->
2725<div class="doc_subsubsection">
2726 <a name="i_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
2727</div>
2728
2729<div class="doc_text">
2730
2731<h5>Syntax:</h5>
2732<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2733 declare void %llvm.pcmarker( uint &lt;id&gt; )
Andrew Lenharthb4427912005-03-28 20:05:49 +0000[diff] [blame]2734</pre>
2735
2736<h5>Overview:</h5>
2737
2738
2739<p>
2740The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a PC in a region of
2741code to simulators and other tools. The method is target specific, but it is
2742expected that the marker will use exported symbols to transmit the PC of the marker.
2743The marker makes no guaranties that it will remain with any specific instruction
2744after optimizations. It is possible that the presense of a marker will inhibit
2745optimizations. The intended use is to be inserted after optmizations to allow
2746corrolations of simulation runs.
2747</p>
2748
2749<h5>Arguments:</h5>
2750
2751<p>
2752<tt>id</tt> is a numerical id identifying the marker.
2753</p>
2754
2755<h5>Semantics:</h5>
2756
2757<p>
2758This intrinsic does not modify the behavior of the program. Backends that do not
2759support this intrinisic may ignore it.
2760</p>
2761
2762</div>
2763
Chris Lattnerc8a2c222005-02-28 19:24:19 +0000[diff] [blame]2764
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2765<!-- ======================================================================= -->
2766<div class="doc_subsection">
2767 <a name="int_os">Operating System Intrinsics</a>
2768</div>
2769
2770<div class="doc_text">
2771<p>
2772These intrinsics are provided by LLVM to support the implementation of
2773operating system level code.
2774</p>
2775
2776</div>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2777
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2778<!-- _______________________________________________________________________ -->
2779<div class="doc_subsubsection">
2780 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2781</div>
2782
2783<div class="doc_text">
2784
2785<h5>Syntax:</h5>
2786<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2787 declare &lt;integer type&gt; %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2788</pre>
2789
2790<h5>Overview:</h5>
2791
2792<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2793The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2794I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2795</p>
2796
2797<h5>Arguments:</h5>
2798
2799<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2800The argument to this intrinsic indicates the hardware I/O address from which
2801to read the data. The address is in the hardware I/O address namespace (as
2802opposed to being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2803</p>
2804
2805<h5>Semantics:</h5>
2806
2807<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2808The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2809specified by <i>address</i> and returns the value. The address and return
2810value must be integers, but the size is dependent upon the platform upon which
2811the program is code generated. For example, on x86, the address must be an
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2812unsigned 16-bit value, and the return value must be 8, 16, or 32 bits.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2813</p>
2814
2815</div>
2816
2817<!-- _______________________________________________________________________ -->
2818<div class="doc_subsubsection">
2819 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2820</div>
2821
2822<div class="doc_text">
2823
2824<h5>Syntax:</h5>
2825<pre>
Chris Lattner74d3f822004-12-09 17:30:23 +0000[diff] [blame]2826 call void (&lt;integer type&gt;, &lt;integer type&gt;)*
2827 %llvm.writeport (&lt;integer type&gt; &lt;value&gt;,
2828 &lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2829</pre>
2830
2831<h5>Overview:</h5>
2832
2833<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2834The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2835I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2836</p>
2837
2838<h5>Arguments:</h5>
2839
2840<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2841The first argument is the value to write to the I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2842</p>
2843
2844<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2845The second argument indicates the hardware I/O address to which data should be
2846written. The address is in the hardware I/O address namespace (as opposed to
2847being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2848</p>
2849
2850<h5>Semantics:</h5>
2851
2852<p>
2853The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2854specified by <i>address</i>. The address and value must be integers, but the
2855size is dependent upon the platform upon which the program is code generated.
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2856For example, on x86, the address must be an unsigned 16-bit value, and the
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2857value written must be 8, 16, or 32 bits in length.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2858</p>
2859
2860</div>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2861
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2862<!-- _______________________________________________________________________ -->
2863<div class="doc_subsubsection">
2864 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
2865</div>
2866
2867<div class="doc_text">
2868
2869<h5>Syntax:</h5>
2870<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2871 declare &lt;result&gt; %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2872</pre>
2873
2874<h5>Overview:</h5>
2875
2876<p>
2877The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
2878address.
2879</p>
2880
2881<h5>Arguments:</h5>
2882
2883<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2884The argument to this intrinsic is a pointer indicating the memory address from
2885which to read the data. The data must be a
2886<a href="#t_firstclass">first class</a> type.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2887</p>
2888
2889<h5>Semantics:</h5>
2890
2891<p>
2892The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2893location specified by <i>pointer</i> and returns the value. The argument must
2894be a pointer, and the return value must be a
2895<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2896may not support I/O on all first class types. For example, 32-bit processors
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2897may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2898</p>
2899
2900<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2901This intrinsic enforces an in-order memory model for llvm.readio and
2902llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2903scheduled processors may execute loads and stores out of order, re-ordering at
2904run time accesses to memory mapped I/O registers. Using these intrinsics
2905ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2906</p>
2907
2908</div>
2909
2910<!-- _______________________________________________________________________ -->
2911<div class="doc_subsubsection">
2912 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
2913</div>
2914
2915<div class="doc_text">
2916
2917<h5>Syntax:</h5>
2918<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]2919 declare void %llvm.writeio (&lt;ty1&gt; &lt;value&gt;, &lt;ty2&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2920</pre>
2921
2922<h5>Overview:</h5>
2923
2924<p>
2925The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
2926mapped I/O address.
2927</p>
2928
2929<h5>Arguments:</h5>
2930
2931<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2932The first argument is the value to write to the memory mapped I/O location.
2933The second argument is a pointer indicating the memory address to which the
2934data should be written.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2935</p>
2936
2937<h5>Semantics:</h5>
2938
2939<p>
2940The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2941I/O address specified by <i>pointer</i>. The value must be a
2942<a href="#t_firstclass">first class</a> type. However, certain architectures
Misha Brukman36c6bc12005-04-22 18:02:52 +0000[diff] [blame]2943may not support I/O on all first class types. For example, 32-bit processors
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2944may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2945</p>
2946
2947<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2948This intrinsic enforces an in-order memory model for llvm.readio and
2949llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2950scheduled processors may execute loads and stores out of order, re-ordering at
2951run time accesses to memory mapped I/O registers. Using these intrinsics
2952ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2953</p>
2954
2955</div>
2956
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2957<!-- ======================================================================= -->
2958<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2959 <a name="int_libc">Standard C Library Intrinsics</a>
2960</div>
2961
2962<div class="doc_text">
2963<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2964LLVM provides intrinsics for a few important standard C library functions.
2965These intrinsics allow source-language front-ends to pass information about the
2966alignment of the pointer arguments to the code generator, providing opportunity
2967for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2968</p>
2969
2970</div>
2971
2972<!-- _______________________________________________________________________ -->
2973<div class="doc_subsubsection">
2974 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
2975</div>
2976
2977<div class="doc_text">
2978
2979<h5>Syntax:</h5>
2980<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]2981 declare void %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
2982 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2983</pre>
2984
2985<h5>Overview:</h5>
2986
2987<p>
2988The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
2989location to the destination location.
2990</p>
2991
2992<p>
2993Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
2994does not return a value, and takes an extra alignment argument.
2995</p>
2996
2997<h5>Arguments:</h5>
2998
2999<p>
3000The first argument is a pointer to the destination, the second is a pointer to
3001the source. The third argument is an (arbitrarily sized) integer argument
3002specifying the number of bytes to copy, and the fourth argument is the alignment
3003of the source and destination locations.
3004</p>
3005
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3006<p>
3007If the call to this intrinisic has an alignment value that is not 0 or 1, then
3008the caller guarantees that the size of the copy is a multiple of the alignment
3009and that both the source and destination pointers are aligned to that boundary.
3010</p>
3011
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]3012<h5>Semantics:</h5>
3013
3014<p>
3015The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
3016location to the destination location, which are not allowed to overlap. It
3017copies "len" bytes of memory over. If the argument is known to be aligned to
3018some boundary, this can be specified as the fourth argument, otherwise it should
3019be set to 0 or 1.
3020</p>
3021</div>
3022
3023
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3024<!-- _______________________________________________________________________ -->
3025<div class="doc_subsubsection">
3026 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
3027</div>
3028
3029<div class="doc_text">
3030
3031<h5>Syntax:</h5>
3032<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3033 declare void %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
3034 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3035</pre>
3036
3037<h5>Overview:</h5>
3038
3039<p>
3040The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
3041location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
3042intrinsic but allows the two memory locations to overlap.
3043</p>
3044
3045<p>
3046Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
3047does not return a value, and takes an extra alignment argument.
3048</p>
3049
3050<h5>Arguments:</h5>
3051
3052<p>
3053The first argument is a pointer to the destination, the second is a pointer to
3054the source. The third argument is an (arbitrarily sized) integer argument
3055specifying the number of bytes to copy, and the fourth argument is the alignment
3056of the source and destination locations.
3057</p>
3058
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]3059<p>
3060If the call to this intrinisic has an alignment value that is not 0 or 1, then
3061the caller guarantees that the size of the copy is a multiple of the alignment
3062and that both the source and destination pointers are aligned to that boundary.
3063</p>
3064
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]3065<h5>Semantics:</h5>
3066
3067<p>
3068The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
3069location to the destination location, which may overlap. It
3070copies "len" bytes of memory over. If the argument is known to be aligned to
3071some boundary, this can be specified as the fourth argument, otherwise it should
3072be set to 0 or 1.
3073</p>
3074</div>
3075
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3076
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3077<!-- _______________________________________________________________________ -->
3078<div class="doc_subsubsection">
3079 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
3080</div>
3081
3082<div class="doc_text">
3083
3084<h5>Syntax:</h5>
3085<pre>
Reid Spencercf669d82005-04-26 20:41:16 +0000[diff] [blame]3086 declare void %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
3087 uint &lt;len&gt;, uint &lt;align&gt;)
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]3088</pre>
3089
3090<h5>Overview:</h5>
3091
3092<p>
3093The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
3094byte value.
3095</p>
3096
3097<p>
3098Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
3099does not return a value, and takes an extra alignment argument.
3100</p>
3101
3102<h5>Arguments:</h5>
3103
3104<p>
3105The first argument is a pointer to the destination to fill, the second is the
3106byte value to fill it with, the third argument is an (arbitrarily sized) integer
3107argument specifying the number of bytes to fill, and the fourth argument is the
3108known alignment of destination location.
3109</p>
3110
3111<p>
3112If the call to this intrinisic has an alignment value that is not 0 or 1, then
3113the caller guarantees that the size of the copy is a multiple of the alignment
3114and that the destination pointer is aligned to that boundary.
3115</p>
3116
3117<h5>Semantics:</h5>
3118
3119<p>
3120The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
3121destination location. If the argument is known to be aligned to some boundary,
3122this can be specified as the fourth argument, otherwise it should be set to 0 or
31231.
3124</p>
3125</div>
3126
3127
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3128<!-- _______________________________________________________________________ -->
3129<div class="doc_subsubsection">
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3130 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
3131</div>
3132
3133<div class="doc_text">
3134
3135<h5>Syntax:</h5>
3136<pre>
Reid Spencer7821d062005-04-26 20:50:44 +0000[diff] [blame]3137 declare bool %llvm.isunordered(&lt;float or double&gt; Val1, &lt;float or double&gt; Val2)
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]3138</pre>
3139
3140<h5>Overview:</h5>
3141
3142<p>
3143The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
3144specified floating point values is a NAN.
3145</p>
3146
3147<h5>Arguments:</h5>
3148
3149<p>
3150The arguments are floating point numbers of the same type.
3151</p>
3152
3153<h5>Semantics:</h5>
3154
3155<p>
3156If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
3157false.
3158</p>
3159</div>
3160
3161
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3162<!-- ======================================================================= -->
3163<div class="doc_subsection">
3164 <a name="int_count">Bit Counting Intrinsics</a>
3165</div>
3166
3167<div class="doc_text">
3168<p>
3169LLVM provides intrinsics for a few important bit counting operations.
3170These allow efficient code generation for some algorithms.
3171</p>
3172
3173</div>
3174
3175<!-- _______________________________________________________________________ -->
3176<div class="doc_subsubsection">
3177 <a name="int_ctpop">'<tt>llvm.ctpop</tt>' Intrinsic</a>
3178</div>
3179
3180<div class="doc_text">
3181
3182<h5>Syntax:</h5>
3183<pre>
3184 declare int %llvm.ctpop(int &lt;src&gt;)
3185
3186</pre>
3187
3188<h5>Overview:</h5>
3189
3190<p>
3191The '<tt>llvm.ctpop</tt>' intrinsic counts the number of ones in a variable.
3192</p>
3193
3194<h5>Arguments:</h5>
3195
3196<p>
Andrew Lenharth5be6f132005-05-04 14:58:31 +0000[diff] [blame]3197The only argument is the value to be counted. The argument may be of any integer type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3198</p>
3199
3200<h5>Semantics:</h5>
3201
3202<p>
3203The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
3204</p>
3205</div>
3206
3207<!-- _______________________________________________________________________ -->
3208<div class="doc_subsubsection">
3209 <a name="int_cttz">'<tt>llvm.cttz</tt>' Intrinsic</a>
3210</div>
3211
3212<div class="doc_text">
3213
3214<h5>Syntax:</h5>
3215<pre>
3216 declare int %llvm.cttz(int &lt;src&gt;)
3217
3218</pre>
3219
3220<h5>Overview:</h5>
3221
3222<p>
3223The '<tt>llvm.cttz</tt>' intrinsic counts the number of trailing zeros.
3224</p>
3225
3226<h5>Arguments:</h5>
3227
3228<p>
Andrew Lenharth5be6f132005-05-04 14:58:31 +0000[diff] [blame]3229The only argument is the value to be counted. The argument may be of any integer type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3230</p>
3231
3232<h5>Semantics:</h5>
3233
3234<p>
3235The '<tt>llvm.cttz</tt>' intrinsic counts the trailing zeros in a variable. If the src == 0
3236then the result is the size in bits of the type of src.
3237</p>
3238</div>
3239
3240<!-- _______________________________________________________________________ -->
3241<div class="doc_subsubsection">
3242 <a name="int_ctlz">'<tt>llvm.ctlz</tt>' Intrinsic</a>
3243</div>
3244
3245<div class="doc_text">
3246
3247<h5>Syntax:</h5>
3248<pre>
3249 declare int %llvm.ctlz(int &lt;src&gt;)
3250
3251</pre>
3252
3253<h5>Overview:</h5>
3254
3255<p>
3256The '<tt>llvm.ctlz</tt>' intrinsic counts the number of leading zeros in a variable.
3257</p>
3258
3259<h5>Arguments:</h5>
3260
3261<p>
Andrew Lenharth5be6f132005-05-04 14:58:31 +0000[diff] [blame]3262The only argument is the value to be counted. The argument may be of any integer type.
Andrew Lenharth1d463522005-05-03 18:01:48 +0000[diff] [blame]3263</p>
3264
3265<h5>Semantics:</h5>
3266
3267<p>
3268The '<tt>llvm.ctlz</tt>' intrinsic counts the leading zeros in a variable. If the src == 0
3269then the result is the size in bits of the type of src.
3270</p>
3271</div>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]3272
3273
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]3274<!-- ======================================================================= -->
3275<div class="doc_subsection">
3276 <a name="int_debugger">Debugger Intrinsics</a>
3277</div>
3278
3279<div class="doc_text">
3280<p>
3281The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
3282are described in the <a
3283href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
3284Debugging</a> document.
3285</p>
3286</div>
3287
3288
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3289<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]3290<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]3291<address>
3292 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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3296
3297 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
3298 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
3299 Last modified: $Date$
3300</address>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]3301</body>
3302</html>