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gerrit-public.fairphone.software / toolchain / llvm-project / 6a4a0492f8a24ef474c34ac311abcedaeba924ba / . / 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 Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]20 <li><a href="#typesystem">Type System</a>
21 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]22 <li><a href="#t_primitive">Primitive Types</a>
23 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]24 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]25 </ol>
26 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]27 <li><a href="#t_derived">Derived Types</a>
28 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]29 <li><a href="#t_array">Array Type</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]30 <li><a href="#t_function">Function Type</a></li>
31 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]32 <li><a href="#t_struct">Structure Type</a></li>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]33 <li><a href="#t_packed">Packed Type</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]34 </ol>
35 </li>
36 </ol>
37 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]38 <li><a href="#highlevel">High Level Structure</a>
39 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]40 <li><a href="#modulestructure">Module Structure</a></li>
41 <li><a href="#globalvars">Global Variables</a></li>
42 <li><a href="#functionstructure">Function Structure</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]43 </ol>
44 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]45 <li><a href="#instref">Instruction Reference</a>
46 <ol>
47 <li><a href="#terminators">Terminator Instructions</a>
48 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]49 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
50 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]51 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
52 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]53 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
54 </ol>
55 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]56 <li><a href="#binaryops">Binary Operations</a>
57 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]58 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
59 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
60 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
61 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
62 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]63 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]64 </ol>
65 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]66 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
67 <ol>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]68 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]69 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]70 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
71 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
72 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]73 </ol>
74 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]75 <li><a href="#memoryops">Memory Access Operations</a>
76 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]77 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
78 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
79 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
80 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
81 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
82 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
83 </ol>
84 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]85 <li><a href="#otherops">Other Operations</a>
86 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]87 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]88 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]89 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]90 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]91 <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]92 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]93 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]94 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]95 </ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]96 </li>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]97 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]98 <ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]99 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
100 <ol>
101 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
102 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
103 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
104 </ol>
105 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]106 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
107 <ol>
108 <li><a href="#i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
109 <li><a href="#i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
110 <li><a href="#i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
111 </ol>
112 </li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]113 <li><a href="#int_codegen">Code Generator Intrinsics</a>
114 <ol>
115 <li><a href="#i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
116 <li><a href="#i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]117 </ol>
118 </li>
119 <li><a href="#int_os">Operating System Intrinsics</a>
120 <ol>
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]121 <li><a href="#i_readport">'<tt>llvm.readport</tt>' Intrinsic</a></li>
122 <li><a href="#i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a></li>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]123 <li><a href="#i_readio">'<tt>llvm.readio</tt>' Intrinsic</a></li>
124 <li><a href="#i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]125 </ol>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]126 <li><a href="#int_libc">Standard C Library Intrinsics</a>
127 <ol>
128 <li><a href="#i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a></li>
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]129 <li><a href="#i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a></li>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]130 <li><a href="#i_memset">'<tt>llvm.memset</tt>' Intrinsic</a></li>
Alkis Evlogimenos9d740622004-06-12 19:19:14 +0000[diff] [blame]131 <li><a href="#i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a></li>
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]132 </ol>
133 </li>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]134 <li><a href="#int_debugger">Debugger intrinsics</a></li>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]135 </ol>
136 </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]137</ol>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]138
139<div class="doc_author">
140 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
141 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]142</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]143
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]144<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]145<div class="doc_section"> <a name="abstract">Abstract </a></div>
146<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]147
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]148<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]149<p>This document is a reference manual for the LLVM assembly language.
150LLVM is an SSA based representation that provides type safety,
151low-level operations, flexibility, and the capability of representing
152'all' high-level languages cleanly. It is the common code
153representation used throughout all phases of the LLVM compilation
154strategy.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]155</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]156
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]157<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]158<div class="doc_section"> <a name="introduction">Introduction</a> </div>
159<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]160
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]161<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]162
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]163<p>The LLVM code representation is designed to be used in three
164different forms: as an in-memory compiler IR, as an on-disk bytecode
165representation (suitable for fast loading by a Just-In-Time compiler),
166and as a human readable assembly language representation. This allows
167LLVM to provide a powerful intermediate representation for efficient
168compiler transformations and analysis, while providing a natural means
169to debug and visualize the transformations. The three different forms
170of LLVM are all equivalent. This document describes the human readable
171representation and notation.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]172
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]173<p>The LLVM representation aims to be a light-weight and low-level
174while being expressive, typed, and extensible at the same time. It
175aims to be a "universal IR" of sorts, by being at a low enough level
176that high-level ideas may be cleanly mapped to it (similar to how
177microprocessors are "universal IR's", allowing many source languages to
178be mapped to them). By providing type information, LLVM can be used as
179the target of optimizations: for example, through pointer analysis, it
180can be proven that a C automatic variable is never accessed outside of
181the current function... allowing it to be promoted to a simple SSA
182value instead of a memory location.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]183
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]184</div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]185
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]186<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]187<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]188
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]189<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]190
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]191<p>It is important to note that this document describes 'well formed'
192LLVM assembly language. There is a difference between what the parser
193accepts and what is considered 'well formed'. For example, the
194following instruction is syntactically okay, but not well formed:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]195
196<pre>
197 %x = <a href="#i_add">add</a> int 1, %x
198</pre>
199
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]200<p>...because the definition of <tt>%x</tt> does not dominate all of
201its uses. The LLVM infrastructure provides a verification pass that may
202be used to verify that an LLVM module is well formed. This pass is
203automatically run by the parser after parsing input assembly, and by
204the optimizer before it outputs bytecode. The violations pointed out
205by the verifier pass indicate bugs in transformation passes or input to
206the parser.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]207
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]208<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]209
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]210<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]211<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]212<!-- *********************************************************************** -->
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]213
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]214<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]215
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]216<p>LLVM uses three different forms of identifiers, for different
217purposes:</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]218
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]219<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]220 <li>Numeric constants are represented as you would expect: 12, -3
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]221123.421, etc. Floating point constants have an optional hexadecimal
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]222notation.</li>
223 <li>Named values are represented as a string of characters with a '%'
224prefix. For example, %foo, %DivisionByZero,
225%a.really.long.identifier. The actual regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
226Identifiers which require other characters in their names can be
227surrounded with quotes. In this way, anything except a <tt>"</tt>
228character can be used in a name.</li>
229 <li>Unnamed values are represented as an unsigned numeric value with
230a '%' prefix. For example, %12, %2, %44.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]231</ol>
John Criswelleb55b522004-03-12 21:19:06 +0000[diff] [blame]232<p>LLVM requires that values start with a '%' sign for two reasons:
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]233Compilers don't need to worry about name clashes with reserved words,
234and the set of reserved words may be expanded in the future without
235penalty. Additionally, unnamed identifiers allow a compiler to quickly
236come up with a temporary variable without having to avoid symbol table
237conflicts.</p>
238<p>Reserved words in LLVM are very similar to reserved words in other
239languages. There are keywords for different opcodes ('<tt><a
240 href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
241 href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
242 href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>',
243etc...), and others. These reserved words cannot conflict with
244variable names, because none of them start with a '%' character.</p>
245<p>Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>'
246by 8:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]247<p>The easy way:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]248<pre> %result = <a href="#i_mul">mul</a> uint %X, 8<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]249<p>After strength reduction:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]250<pre> %result = <a href="#i_shl">shl</a> uint %X, ubyte 3<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]251<p>And the hard way:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]252<pre> <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
253 <a
254 href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
255 %result = <a
256 href="#i_add">add</a> uint %1, %1<br></pre>
257<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
258important lexical features of LLVM:</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]259<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]260 <li>Comments are delimited with a '<tt>;</tt>' and go until the end
261of line.</li>
262 <li>Unnamed temporaries are created when the result of a computation
263is not assigned to a named value.</li>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]264 <li>Unnamed temporaries are numbered sequentially</li>
265</ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]266<p>...and it also show a convention that we follow in this document.
267When demonstrating instructions, we will follow an instruction with a
268comment that defines the type and name of value produced. Comments are
269shown in italic text.</p>
270<p>The one non-intuitive notation for constants is the optional
271hexidecimal form of floating point constants. For example, the form '<tt>double
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]2720x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]2734.5e+15</tt>' which is also supported by the parser. The only time
274hexadecimal floating point constants are useful (and the only time that
275they are generated by the disassembler) is when an FP constant has to
276be emitted that is not representable as a decimal floating point number
277exactly. For example, NaN's, infinities, and other special cases are
278represented in their IEEE hexadecimal format so that assembly and
279disassembly do not cause any bits to change in the constants.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]280</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]281<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]282<div class="doc_section"> <a name="typesystem">Type System</a> </div>
283<!-- *********************************************************************** -->
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]284<div class="doc_text">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]285<p>The LLVM type system is one of the most important features of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]286intermediate representation. Being typed enables a number of
287optimizations to be performed on the IR directly, without having to do
288extra analyses on the side before the transformation. A strong type
289system makes it easier to read the generated code and enables novel
290analyses and transformations that are not feasible to perform on normal
291three address code representations.</p>
Chris Lattnerd8f8ede2002-06-25 18:03:17 +0000[diff] [blame]292<!-- The written form for the type system was heavily influenced by the
293syntactic problems with types in the C language<sup><a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]294href="#rw_stroustrup">1</a></sup>.<p> --> </div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]295<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]296<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]297<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]298<p>The primitive types are the fundamental building blocks of the LLVM
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]299system. The current set of primitive types are as follows:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]300
301<table border="0" style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]302 <tbody>
303 <tr>
304 <td>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]305 <table border="1" cellspacing="0" cellpadding="4" style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]306 <tbody>
307 <tr>
308 <td><tt>void</tt></td>
309 <td>No value</td>
310 </tr>
311 <tr>
312 <td><tt>ubyte</tt></td>
313 <td>Unsigned 8 bit value</td>
314 </tr>
315 <tr>
316 <td><tt>ushort</tt></td>
317 <td>Unsigned 16 bit value</td>
318 </tr>
319 <tr>
320 <td><tt>uint</tt></td>
321 <td>Unsigned 32 bit value</td>
322 </tr>
323 <tr>
324 <td><tt>ulong</tt></td>
325 <td>Unsigned 64 bit value</td>
326 </tr>
327 <tr>
328 <td><tt>float</tt></td>
329 <td>32 bit floating point value</td>
330 </tr>
331 <tr>
332 <td><tt>label</tt></td>
333 <td>Branch destination</td>
334 </tr>
335 </tbody>
336 </table>
337 </td>
338 <td valign="top">
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]339 <table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]340 <tbody>
341 <tr>
342 <td><tt>bool</tt></td>
343 <td>True or False value</td>
344 </tr>
345 <tr>
346 <td><tt>sbyte</tt></td>
347 <td>Signed 8 bit value</td>
348 </tr>
349 <tr>
350 <td><tt>short</tt></td>
351 <td>Signed 16 bit value</td>
352 </tr>
353 <tr>
354 <td><tt>int</tt></td>
355 <td>Signed 32 bit value</td>
356 </tr>
357 <tr>
358 <td><tt>long</tt></td>
359 <td>Signed 64 bit value</td>
360 </tr>
361 <tr>
362 <td><tt>double</tt></td>
363 <td>64 bit floating point value</td>
364 </tr>
365 </tbody>
366 </table>
367 </td>
368 </tr>
369 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]370</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]371
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]372</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]373<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]374<div class="doc_subsubsection"> <a name="t_classifications">Type
375Classifications</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]376<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]377<p>These different primitive types fall into a few useful
378classifications:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]379
380<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]381 <tbody>
382 <tr>
383 <td><a name="t_signed">signed</a></td>
384 <td><tt>sbyte, short, int, long, float, double</tt></td>
385 </tr>
386 <tr>
387 <td><a name="t_unsigned">unsigned</a></td>
388 <td><tt>ubyte, ushort, uint, ulong</tt></td>
389 </tr>
390 <tr>
391 <td><a name="t_integer">integer</a></td>
392 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
393 </tr>
394 <tr>
395 <td><a name="t_integral">integral</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]396 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt>
397 </td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]398 </tr>
399 <tr>
400 <td><a name="t_floating">floating point</a></td>
401 <td><tt>float, double</tt></td>
402 </tr>
403 <tr>
404 <td><a name="t_firstclass">first class</a></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]405 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long,<br>
406 float, double, <a href="#t_pointer">pointer</a>,
407 <a href="#t_packed">packed</a></tt></td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]408 </tr>
409 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]410</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]411
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]412<p>The <a href="#t_firstclass">first class</a> types are perhaps the
413most important. Values of these types are the only ones which can be
414produced by instructions, passed as arguments, or used as operands to
415instructions. This means that all structures and arrays must be
416manipulated either by pointer or by component.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]417</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]418<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]419<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]420<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]421<p>The real power in LLVM comes from the derived types in the system.
422This is what allows a programmer to represent arrays, functions,
423pointers, and other useful types. Note that these derived types may be
424recursive: For example, it is possible to have a two dimensional array.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]425</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]426<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]427<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]428<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]429<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]430<p>The array type is a very simple derived type that arranges elements
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]431sequentially in memory. The array type requires a size (number of
432elements) and an underlying data type.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]433<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]434<pre> [&lt;# elements&gt; x &lt;elementtype&gt;]<br></pre>
435<p>The number of elements is a constant integer value, elementtype may
436be any type with a size.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]437<h5>Examples:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]438<p> <tt>[40 x int ]</tt>: Array of 40 integer values.<br>
439<tt>[41 x int ]</tt>: Array of 41 integer values.<br>
440<tt>[40 x uint]</tt>: Array of 40 unsigned integer values.</p>
441<p> </p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]442<p>Here are some examples of multidimensional arrays:</p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]443
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]444<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]445 <tbody>
446 <tr>
447 <td><tt>[3 x [4 x int]]</tt></td>
448 <td>: 3x4 array integer values.</td>
449 </tr>
450 <tr>
451 <td><tt>[12 x [10 x float]]</tt></td>
452 <td>: 12x10 array of single precision floating point values.</td>
453 </tr>
454 <tr>
455 <td><tt>[2 x [3 x [4 x uint]]]</tt></td>
456 <td>: 2x3x4 array of unsigned integer values.</td>
457 </tr>
458 </tbody>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]459</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]460
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]461</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]462<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]463<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]464<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]465<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]466<p>The function type can be thought of as a function signature. It
467consists of a return type and a list of formal parameter types.
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]468Function types are usually used to build virtual function tables
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]469(which are structures of pointers to functions), for indirect function
470calls, and when defining a function.</p>
John Criswella0d50d22003-11-25 21:45:46 +0000[diff] [blame]471<p>
472The return type of a function type cannot be an aggregate type.
473</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]474<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]475<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]476<p>Where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
477specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]478which indicates that the function takes a variable number of arguments.
479Variable argument functions can access their arguments with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]480 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]481<h5>Examples:</h5>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]482
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]483<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]484 <tbody>
485 <tr>
486 <td><tt>int (int)</tt></td>
487 <td>: function taking an <tt>int</tt>, returning an <tt>int</tt></td>
488 </tr>
489 <tr>
490 <td><tt>float (int, int *) *</tt></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]491 <td>: <a href="#t_pointer">Pointer</a> to a function that takes an
492 <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
493 returning <tt>float</tt>.</td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]494 </tr>
495 <tr>
496 <td><tt>int (sbyte *, ...)</tt></td>
497 <td>: A vararg function that takes at least one <a
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]498 href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C), which
499 returns an integer. This is the signature for <tt>printf</tt> in
500 LLVM.</td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]501 </tr>
502 </tbody>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]503</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]504
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]505</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]506<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]507<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]508<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]509<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]510<p>The structure type is used to represent a collection of data members
511together in memory. The packing of the field types is defined to match
512the ABI of the underlying processor. The elements of a structure may
513be any type that has a size.</p>
514<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
515and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
516field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
517instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]518<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]519<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]520<h5>Examples:</h5>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]521
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]522<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]523 <tbody>
524 <tr>
525 <td><tt>{ int, int, int }</tt></td>
526 <td>: a triple of three <tt>int</tt> values</td>
527 </tr>
528 <tr>
529 <td><tt>{ float, int (int) * }</tt></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]530 <td>: A pair, where the first element is a <tt>float</tt> and the second
531 element is a <a href="#t_pointer">pointer</a> to a <a
532 href="#t_function">function</a> that takes an <tt>int</tt>, returning an
533 <tt>int</tt>.</td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]534 </tr>
535 </tbody>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]536</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]537
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]538</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]539<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]540<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]541<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]542<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]543<p>As in many languages, the pointer type represents a pointer or
544reference to another object, which must live in memory.</p>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]545<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]546<pre> &lt;type&gt; *<br></pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]547<h5>Examples:</h5>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]548
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]549<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]550 <tbody>
551 <tr>
552 <td><tt>[4x int]*</tt></td>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]553 <td>: <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
554 four <tt>int</tt> values</td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]555 </tr>
556 <tr>
557 <td><tt>int (int *) *</tt></td>
558 <td>: A <a href="#t_pointer">pointer</a> to a <a
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]559 href="#t_function">function</a> that takes an <tt>int</tt>, returning an
560 <tt>int</tt>.</td>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]561 </tr>
562 </tbody>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]563</table>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]564</div>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]565<!-- _______________________________________________________________________ -->
566<div class="doc_subsubsection"> <a name="t_packed">Packed Type</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]567<div class="doc_text">
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]568<h5>Overview:</h5>
569<p>A packed type is a simple derived type that represents a vector
570of elements. Packed types are used when multiple primitive data
571are operated in parallel using a single instruction (SIMD).
572A packed type requires a size (number of
573elements) and an underlying primitive data type. Packed types are
574considered <a href="#t_firstclass">first class</a>.</p>
575<h5>Syntax:</h5>
576<pre> &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;<br></pre>
577<p>The number of elements is a constant integer value, elementtype may
578be any integral or floating point type.</p>
579<h5>Examples:</h5>
580<p> <tt>&lt;4 x int&gt;</tt>: Packed vector of 4 integer values.<br>
581<tt>&lt;8 x float&gt;</tt>: Packed vector of 8 floating-point values.<br>
582<tt>&lt;2 x uint&gt;</tt>: Packed vector of 2 unsigned integer values.</p>
583<p> </p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]584</div>
585
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]586<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]587<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
Misha Brukman20f9a622004-08-12 20:16:08 +0000[diff] [blame]588<!-- *********************************************************************** -->
589<!-- ======================================================================= -->
590<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
591</div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]592<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]593<p>LLVM programs are composed of "Module"s, each of which is a
594translation unit of the input programs. Each module consists of
595functions, global variables, and symbol table entries. Modules may be
596combined together with the LLVM linker, which merges function (and
597global variable) definitions, resolves forward declarations, and merges
598symbol table entries. Here is an example of the "hello world" module:</p>
599<pre><i>; Declare the string constant as a global constant...</i>
600<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
601 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]602
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]603<i>; External declaration of the puts function</i>
604<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]605
606<i>; Definition of main function</i>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]607int %main() { <i>; int()* </i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]608 <i>; Convert [13x sbyte]* to sbyte *...</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]609 %cast210 = <a
610 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]611
612 <i>; Call puts function to write out the string to stdout...</i>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]613 <a
614 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
615 <a
616 href="#i_ret">ret</a> int 0<br>}<br></pre>
617<p>This example is made up of a <a href="#globalvars">global variable</a>
618named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
619function, and a <a href="#functionstructure">function definition</a>
620for "<tt>main</tt>".</p>
621<a name="linkage"> In general, a module is made up of a list of global
622values, where both functions and global variables are global values.
623Global values are represented by a pointer to a memory location (in
624this case, a pointer to an array of char, and a pointer to a function),
625and have one of the following linkage types:</a>
626<p> </p>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]627<dl>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]628 <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]629 <dd>Global values with internal linkage are only directly accessible
630by objects in the current module. In particular, linking code into a
631module with an internal global value may cause the internal to be
632renamed as necessary to avoid collisions. Because the symbol is
633internal to the module, all references can be updated. This
634corresponds to the notion of the '<tt>static</tt>' keyword in C, or the
635idea of "anonymous namespaces" in C++.
636 <p> </p>
637 </dd>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]638 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]639 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt>
640linkage, with the twist that linking together two modules defining the
641same <tt>linkonce</tt> globals will cause one of the globals to be
642discarded. This is typically used to implement inline functions.
643Unreferenced <tt>linkonce</tt> globals are allowed to be discarded.
644 <p> </p>
645 </dd>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]646 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]647 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt>
648linkage, except that unreferenced <tt>weak</tt> globals may not be
649discarded. This is used to implement constructs in C such as "<tt>int
650X;</tt>" at global scope.
651 <p> </p>
652 </dd>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]653 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]654 <dd>"<tt>appending</tt>" linkage may only be applied to global
655variables of pointer to array type. When two global variables with
656appending linkage are linked together, the two global arrays are
657appended together. This is the LLVM, typesafe, equivalent of having
658the system linker append together "sections" with identical names when
659.o files are linked.
660 <p> </p>
661 </dd>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]662 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]663 <dd>If none of the above identifiers are used, the global is
664externally visible, meaning that it participates in linkage and can be
665used to resolve external symbol references.
666 <p> </p>
667 </dd>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]668</dl>
669<p> </p>
670<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
671variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
672variable and was linked with this one, one of the two would be renamed,
673preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
674external (i.e., lacking any linkage declarations), they are accessible
675outside of the current module. It is illegal for a function <i>declaration</i>
676to have any linkage type other than "externally visible".</a></p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]677</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]678
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]679<!-- ======================================================================= -->
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]680<div class="doc_subsection">
681 <a name="globalvars">Global Variables</a>
682</div>
683
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]684<div class="doc_text">
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]685
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]686<p>Global variables define regions of memory allocated at compilation
687time instead of run-time. Global variables may optionally be
688initialized. A variable may be defined as a global "constant", which
689indicates that the contents of the variable will never be modified
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]690(opening options for optimization).</p>
691
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]692<p>As SSA values, global variables define pointer values that are in
693scope (i.e. they dominate) for all basic blocks in the program. Global
694variables always define a pointer to their "content" type because they
695describe a region of memory, and all memory objects in LLVM are
696accessed through pointers.</p>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]697
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]698</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]699
700
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]701<!-- ======================================================================= -->
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]702<div class="doc_subsection">
703 <a name="functionstructure">Functions</a>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]704</div>
Chris Lattnerb1652612004-03-08 16:49:10 +0000[diff] [blame]705
706<div class="doc_text">
707
708<p>LLVM function definitions are composed of a (possibly empty) argument list,
709an opening curly brace, a list of basic blocks, and a closing curly brace. LLVM
710function declarations are defined with the "<tt>declare</tt>" keyword, a
711function name, and a function signature.</p>
712
713<p>A function definition contains a list of basic blocks, forming the CFG for
714the function. Each basic block may optionally start with a label (giving the
715basic block a symbol table entry), contains a list of instructions, and ends
716with a <a href="#terminators">terminator</a> instruction (such as a branch or
717function return).</p>
718
719<p>The first basic block in program is special in two ways: it is immediately
720executed on entrance to the function, and it is not allowed to have predecessor
721basic blocks (i.e. there can not be any branches to the entry block of a
722function). Because the block can have no predecessors, it also cannot have any
723<a href="#i_phi">PHI nodes</a>.</p>
724
725<p>LLVM functions are identified by their name and type signature. Hence, two
726functions with the same name but different parameter lists or return values are
727considered different functions, and LLVM will resolves references to each
728appropriately.</p>
729
730</div>
731
732
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]733<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]734<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
735<!-- *********************************************************************** -->
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]736<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]737<p>The LLVM instruction set consists of several different
738classifications of instructions: <a href="#terminators">terminator
739instructions</a>, <a href="#binaryops">binary instructions</a>, <a
740 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
741instructions</a>.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]742</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]743<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]744<div class="doc_subsection"> <a name="terminators">Terminator
745Instructions</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]746<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]747<p>As mentioned <a href="#functionstructure">previously</a>, every
748basic block in a program ends with a "Terminator" instruction, which
749indicates which block should be executed after the current block is
750finished. These terminator instructions typically yield a '<tt>void</tt>'
751value: they produce control flow, not values (the one exception being
752the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]753<p>There are five different terminator instructions: the '<a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]754 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
755instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
756the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, and the '<a
757 href="#i_unwind"><tt>unwind</tt></a>' instruction.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]758</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]759<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]760<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
761Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]762<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]763<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]764<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]765 ret void <i>; Return from void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]766</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]767<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]768<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
769value) from a function, back to the caller.</p>
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]770<p>There are two forms of the '<tt>ret</tt>' instruction: one that
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]771returns a value and then causes control flow, and one that just causes
772control flow to occur.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]773<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]774<p>The '<tt>ret</tt>' instruction may return any '<a
775 href="#t_firstclass">first class</a>' type. Notice that a function is
776not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
777instruction inside of the function that returns a value that does not
778match the return type of the function.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]779<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]780<p>When the '<tt>ret</tt>' instruction is executed, control flow
781returns back to the calling function's context. If the caller is a "<a
John Criswell40db33f2004-06-25 15:16:57 +0000[diff] [blame]782 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]783the instruction after the call. If the caller was an "<a
784 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
785at the beginning "normal" of the destination block. If the instruction
786returns a value, that value shall set the call or invoke instruction's
787return value.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]788<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]789<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]790 ret void <i>; Return from a void function</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]791</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]792</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]793<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]794<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]795<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]796<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]797<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]798</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]799<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]800<p>The '<tt>br</tt>' instruction is used to cause control flow to
801transfer to a different basic block in the current function. There are
802two forms of this instruction, corresponding to a conditional branch
803and an unconditional branch.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]804<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]805<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
806single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
807unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
808value as a target.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]809<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]810<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
811argument is evaluated. If the value is <tt>true</tt>, control flows
812to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
813control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]814<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]815<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
816 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]817</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]818<!-- _______________________________________________________________________ -->
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]819<div class="doc_subsubsection">
820 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
821</div>
822
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]823<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]824<h5>Syntax:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]825
826<pre>
827 switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
828</pre>
829
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]830<h5>Overview:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]831
832<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
833several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]834instruction, allowing a branch to occur to one of many possible
835destinations.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]836
837
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]838<h5>Arguments:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]839
840<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
841comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
842an array of pairs of comparison value constants and '<tt>label</tt>'s. The
843table is not allowed to contain duplicate constant entries.</p>
844
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]845<h5>Semantics:</h5>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]846
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]847<p>The <tt>switch</tt> instruction specifies a table of values and
848destinations. When the '<tt>switch</tt>' instruction is executed, this
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]849table is searched for the given value. If the value is found, control flow is
850transfered to the corresponding destination; otherwise, control flow is
851transfered to the default destination.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]852
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]853<h5>Implementation:</h5>
854
855<p>Depending on properties of the target machine and the particular
856<tt>switch</tt> instruction, this instruction may be code generated in different
John Criswellbcbb18c2004-06-25 16:05:06 +0000[diff] [blame]857ways. For example, it could be generated as a series of chained conditional
858branches or with a lookup table.</p>
Chris Lattnercf96c6c2004-02-24 04:54:45 +0000[diff] [blame]859
860<h5>Example:</h5>
861
862<pre>
863 <i>; Emulate a conditional br instruction</i>
864 %Val = <a href="#i_cast">cast</a> bool %value to int
865 switch int %Val, label %truedest [int 0, label %falsedest ]
866
867 <i>; Emulate an unconditional br instruction</i>
868 switch uint 0, label %dest [ ]
869
870 <i>; Implement a jump table:</i>
871 switch uint %val, label %otherwise [ uint 0, label %onzero
872 uint 1, label %onone
873 uint 2, label %ontwo ]
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]874</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]875</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]876<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]877<div class="doc_subsubsection"> <a name="i_invoke">'<tt>invoke</tt>'
878Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]879<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]880<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]881<pre> &lt;result&gt; = invoke &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)<br> to label &lt;normal label&gt; except label &lt;exception label&gt;<br></pre>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]882<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]883<p>The '<tt>invoke</tt>' instruction causes control to transfer to a
884specified function, with the possibility of control flow transfer to
885either the '<tt>normal</tt>' <tt>label</tt> label or the '<tt>exception</tt>'<tt>label</tt>.
886If the callee function returns with the "<tt><a href="#i_ret">ret</a></tt>"
887instruction, control flow will return to the "normal" label. If the
888callee (or any indirect callees) returns with the "<a href="#i_unwind"><tt>unwind</tt></a>"
889instruction, control is interrupted, and continued at the dynamically
890nearest "except" label.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]891<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]892<p>This instruction requires several arguments:</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]893<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]894 <li>'<tt>ptr to function ty</tt>': shall be the signature of the
895pointer to function value being invoked. In most cases, this is a
896direct function invocation, but indirect <tt>invoke</tt>s are just as
897possible, branching off an arbitrary pointer to function value. </li>
898 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer
899to a function to be invoked. </li>
900 <li>'<tt>function args</tt>': argument list whose types match the
901function signature argument types. If the function signature indicates
902the function accepts a variable number of arguments, the extra
903arguments can be specified. </li>
904 <li>'<tt>normal label</tt>': the label reached when the called
905function executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
906 <li>'<tt>exception label</tt>': the label reached when a callee
907returns with the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]908</ol>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]909<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]910<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]911 href="#i_call">call</a></tt>' instruction in most regards. The
912primary difference is that it establishes an association with a label,
913which is used by the runtime library to unwind the stack.</p>
914<p>This instruction is used in languages with destructors to ensure
915that proper cleanup is performed in the case of either a <tt>longjmp</tt>
916or a thrown exception. Additionally, this is important for
917implementation of '<tt>catch</tt>' clauses in high-level languages that
918support them.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]919<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]920<pre> %retval = invoke int %Test(int 15)<br> to label %Continue<br> except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]921</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]922</div>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]923<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]924<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
925Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]926<div class="doc_text">
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]927<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]928<pre> unwind<br></pre>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]929<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]930<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing
931control flow at the first callee in the dynamic call stack which used
932an <a href="#i_invoke"><tt>invoke</tt></a> instruction to perform the
933call. This is primarily used to implement exception handling.</p>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]934<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]935<p>The '<tt>unwind</tt>' intrinsic causes execution of the current
936function to immediately halt. The dynamic call stack is then searched
937for the first <a href="#i_invoke"><tt>invoke</tt></a> instruction on
938the call stack. Once found, execution continues at the "exceptional"
939destination block specified by the <tt>invoke</tt> instruction. If
940there is no <tt>invoke</tt> instruction in the dynamic call chain,
941undefined behavior results.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]942</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]943<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]944<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]945<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]946<p>Binary operators are used to do most of the computation in a
947program. They require two operands, execute an operation on them, and
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]948produce a single value. Although, that single value might represent
949multiple data, as is the case with the <a href="#t_packed">packed</a> data type.
950The result value of a binary operator is not
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]951necessarily the same type as its operands.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]952<p>There are several different binary operators:</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]953</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]954<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]955<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
956Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]957<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]958<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]959<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]960</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]961<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]962<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]963<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]964<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]965 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
966 This instruction can also take <a href="#t_packed">packed</a> versions of the values.
967Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]968<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]969<p>The value produced is the integer or floating point sum of the two
970operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]971<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]972<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]973</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]974</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]975<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]976<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
977Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]978<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]979<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]980<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]981</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]982<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]983<p>The '<tt>sub</tt>' instruction returns the difference of its two
984operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]985<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
986instruction present in most other intermediate representations.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]987<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]988<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]989 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]990values.
991This instruction can also take <a href="#t_packed">packed</a> versions of the values.
992Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]993<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]994<p>The value produced is the integer or floating point difference of
995the two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]996<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]997<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]998 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
999</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1000</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1001<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1002<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
1003Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1004<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1005<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1006<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]1007</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1008<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1009<p>The '<tt>mul</tt>' instruction returns the product of its two
1010operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1011<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1012<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1013 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1014values.
1015This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1016Both arguments must have identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1017<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1018<p>The value produced is the integer or floating point product of the
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1019two operands.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1020<p>There is no signed vs unsigned multiplication. The appropriate
1021action is taken based on the type of the operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1022<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1023<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]1024</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1025</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1026<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1027<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
1028Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1029<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1030<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1031<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1032</pre>
1033<h5>Overview:</h5>
1034<p>The '<tt>div</tt>' instruction returns the quotient of its two
1035operands.</p>
1036<h5>Arguments:</h5>
1037<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
1038 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1039values.
1040This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1041Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1042<h5>Semantics:</h5>
1043<p>The value produced is the integer or floating point quotient of the
1044two operands.</p>
1045<h5>Example:</h5>
1046<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
1047</pre>
1048</div>
1049<!-- _______________________________________________________________________ -->
1050<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
1051Instruction</a> </div>
1052<div class="doc_text">
1053<h5>Syntax:</h5>
1054<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1055</pre>
1056<h5>Overview:</h5>
1057<p>The '<tt>rem</tt>' instruction returns the remainder from the
1058division of its two operands.</p>
1059<h5>Arguments:</h5>
1060<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
1061 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattnerc8cb6952004-08-12 19:12:28 +0000[diff] [blame]1062values.
1063This instruction can also take <a href="#t_packed">packed</a> versions of the values.
1064Both arguments must have identical types.</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1065<h5>Semantics:</h5>
1066<p>This returns the <i>remainder</i> of a division (where the result
1067has the same sign as the divisor), not the <i>modulus</i> (where the
1068result has the same sign as the dividend) of a value. For more
1069information about the difference, see: <a
1070 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
1071Math Forum</a>.</p>
1072<h5>Example:</h5>
1073<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
1074</pre>
1075</div>
1076<!-- _______________________________________________________________________ -->
1077<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
1078Instructions</a> </div>
1079<div class="doc_text">
1080<h5>Syntax:</h5>
1081<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]1082 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1083 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1084 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1085 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1086 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
1087</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1088<h5>Overview:</h5>
1089<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
1090value based on a comparison of their two operands.</p>
1091<h5>Arguments:</h5>
1092<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
1093be of <a href="#t_firstclass">first class</a> type (it is not possible
1094to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
1095or '<tt>void</tt>' values, etc...). Both arguments must have identical
1096types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1097<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1098<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1099value if both operands are equal.<br>
1100The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1101value if both operands are unequal.<br>
1102The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1103value if the first operand is less than the second operand.<br>
1104The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1105value if the first operand is greater than the second operand.<br>
1106The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1107value if the first operand is less than or equal to the second operand.<br>
1108The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
1109value if the first operand is greater than or equal to the second
1110operand.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1111<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1112<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1113 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1114 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1115 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1116 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1117 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1118</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1119</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1120<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1121<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1122Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1123<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1124<p>Bitwise binary operators are used to do various forms of
1125bit-twiddling in a program. They are generally very efficient
1126instructions, and can commonly be strength reduced from other
1127instructions. They require two operands, execute an operation on them,
1128and produce a single value. The resulting value of the bitwise binary
1129operators is always the same type as its first operand.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1130</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1131<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1132<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1133Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1134<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1135<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1136<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]1137</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1138<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1139<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1140its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1141<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1142<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1143 href="#t_integral">integral</a> values. Both arguments must have
1144identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1145<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1146<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1147<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1148<div style="align: center">
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1149<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1150 <tbody>
1151 <tr>
1152 <td>In0</td>
1153 <td>In1</td>
1154 <td>Out</td>
1155 </tr>
1156 <tr>
1157 <td>0</td>
1158 <td>0</td>
1159 <td>0</td>
1160 </tr>
1161 <tr>
1162 <td>0</td>
1163 <td>1</td>
1164 <td>0</td>
1165 </tr>
1166 <tr>
1167 <td>1</td>
1168 <td>0</td>
1169 <td>0</td>
1170 </tr>
1171 <tr>
1172 <td>1</td>
1173 <td>1</td>
1174 <td>1</td>
1175 </tr>
1176 </tbody>
1177</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1178</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1179<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1180<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]1181 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1182 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1183</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1184</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1185<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1186<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1187<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1188<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1189<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]1190</pre>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1191<h5>Overview:</h5>
1192<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1193or of its two operands.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1194<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1195<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1196 href="#t_integral">integral</a> values. Both arguments must have
1197identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1198<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1199<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1200<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1201<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1202<table border="1" cellspacing="0" cellpadding="4">
1203 <tbody>
1204 <tr>
1205 <td>In0</td>
1206 <td>In1</td>
1207 <td>Out</td>
1208 </tr>
1209 <tr>
1210 <td>0</td>
1211 <td>0</td>
1212 <td>0</td>
1213 </tr>
1214 <tr>
1215 <td>0</td>
1216 <td>1</td>
1217 <td>1</td>
1218 </tr>
1219 <tr>
1220 <td>1</td>
1221 <td>0</td>
1222 <td>1</td>
1223 </tr>
1224 <tr>
1225 <td>1</td>
1226 <td>1</td>
1227 <td>1</td>
1228 </tr>
1229 </tbody>
1230</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1231</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1232<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1233<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]1234 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1235 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1236</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1237</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1238<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1239<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1240Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1241<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1242<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1243<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]1244</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1245<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1246<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1247or of its two operands. The <tt>xor</tt> is used to implement the
1248"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1249<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1250<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1251 href="#t_integral">integral</a> values. Both arguments must have
1252identical types.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1253<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1254<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1255<p> </p>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1256<div style="align: center">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1257<table border="1" cellspacing="0" cellpadding="4">
1258 <tbody>
1259 <tr>
1260 <td>In0</td>
1261 <td>In1</td>
1262 <td>Out</td>
1263 </tr>
1264 <tr>
1265 <td>0</td>
1266 <td>0</td>
1267 <td>0</td>
1268 </tr>
1269 <tr>
1270 <td>0</td>
1271 <td>1</td>
1272 <td>1</td>
1273 </tr>
1274 <tr>
1275 <td>1</td>
1276 <td>0</td>
1277 <td>1</td>
1278 </tr>
1279 <tr>
1280 <td>1</td>
1281 <td>1</td>
1282 <td>0</td>
1283 </tr>
1284 </tbody>
1285</table>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]1286</div>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1287<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1288<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1289<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]1290 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1291 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner5ed60612003-09-03 00:41:47 +0000[diff] [blame]1292 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</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 Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1295<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1296<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1297Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1298<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1299<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1300<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]1301</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1302<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1303<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1304the left a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1305<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1306<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1307 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1308type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1309<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1310<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]1311<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1312<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]1313 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1314 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1315</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1316</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1317<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1318<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1319Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1320<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1321<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1322<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]1323</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1324<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1325<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1326the right a specified number of bits.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1327<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1328<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1329 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1330type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1331<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1332<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1333most significant bit is duplicated in the newly free'd bit positions.
1334If the first argument is unsigned, zero bits shall fill the empty
1335positions.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1336<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1337<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]1338 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1339 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner33426d92003-06-18 21:30:51 +0000[diff] [blame]1340 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1341 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1342</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1343</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1344<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1345<div class="doc_subsection"> <a name="memoryops">Memory Access
1346Operations</a></div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1347<div class="doc_text">
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1348<p>A key design point of an SSA-based representation is how it
1349represents memory. In LLVM, no memory locations are in SSA form, which
1350makes things very simple. This section describes how to read, write,
1351allocate and free memory in LLVM.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1352</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1353<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1354<div class="doc_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>'
1355Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1356<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1357<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1358<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]1359 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1360</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1361<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1362<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1363heap and returns a pointer to it.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1364<h5>Arguments:</h5>
John Criswella92e5862004-02-24 16:13:56 +0000[diff] [blame]1365<p>The '<tt>malloc</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1366bytes of memory from the operating system and returns a pointer of the
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1367appropriate type to the program. The second form of the instruction is
1368a shorter version of the first instruction that defaults to allocating
1369one element.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1370<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1371<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1372<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1373a pointer is returned.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1374<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1375<pre> %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1376
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1377 %size = <a
1378 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]1379 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1380 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1381</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1382</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1383<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1384<div class="doc_subsubsection"> <a name="i_free">'<tt>free</tt>'
1385Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1386<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1387<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1388<pre> free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1389</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1390<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1391<p>The '<tt>free</tt>' instruction returns memory back to the unused
1392memory heap, to be reallocated in the future.</p>
1393<p> </p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1394<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1395<p>'<tt>value</tt>' shall be a pointer value that points to a value
1396that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1397instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1398<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1399<p>Access to the memory pointed to by the pointer is not longer defined
1400after this instruction executes.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1401<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1402<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]1403 free [4 x ubyte]* %array
1404</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1405</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1406<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1407<div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>'
1408Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1409<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1410<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1411<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]1412 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1413</pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1414<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1415<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1416stack frame of the procedure that is live until the current function
1417returns to its caller.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1418<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1419<p>The the '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1420bytes of memory on the runtime stack, returning a pointer of the
1421appropriate type to the program. The second form of the instruction is
1422a shorter version of the first that defaults to allocating one element.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1423<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1424<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1425<p>Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d
1426memory is automatically released when the function returns. The '<tt>alloca</tt>'
1427instruction is commonly used to represent automatic variables that must
1428have an address available. When the function returns (either with the <tt><a
1429 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]1430instructions), the memory is reclaimed.</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> %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1433 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1434</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1435</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1436<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1437<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1438Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1439<div class="doc_text">
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1440<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1441<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]1442<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1443<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1444<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1445<p>The argument to the '<tt>load</tt>' instruction specifies the memory
1446address to load from. The pointer must point to a <a
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1447 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1448marked as <tt>volatile</tt> then the optimizer is not allowed to modify
1449the number or order of execution of this <tt>load</tt> with other
1450volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1451instructions. </p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1452<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1453<p>The location of memory pointed to is loaded.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1454<h5>Examples:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1455<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1456 <a
1457 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1458 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1459</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1460</div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1461<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1462<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1463Instruction</a> </div>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1464<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1465<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]1466 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]1467</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1468<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1469<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1470<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1471<p>There are two arguments to the '<tt>store</tt>' instruction: a value
1472to store and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1473operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
1474operand. If the <tt>store</tt> is marked as <tt>volatile</tt> then the
1475optimizer is not allowed to modify the number or order of execution of
1476this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1477 href="#i_store">store</a></tt> instructions.</p>
1478<h5>Semantics:</h5>
1479<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1480at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1481<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1482<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1483 <a
1484 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1485 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1486</pre>
Chris Lattner095735d2002-05-06 03:03:22 +0000[diff] [blame]1487<!-- _______________________________________________________________________ -->
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1488<div class="doc_subsubsection">
1489 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
1490</div>
1491
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1492<div class="doc_text">
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1493<h5>Syntax:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1494<pre>
1495 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
1496</pre>
1497
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1498<h5>Overview:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1499
1500<p>
1501The '<tt>getelementptr</tt>' instruction is used to get the address of a
1502subelement of an aggregate data structure.</p>
1503
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1504<h5>Arguments:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1505
1506<p>This instruction takes a list of integer constants that indicate what
1507elements of the aggregate object to index to. The actual types of the arguments
1508provided depend on the type of the first pointer argument. The
1509'<tt>getelementptr</tt>' instruction is used to index down through the type
1510levels of a structure. When indexing into a structure, only <tt>uint</tt>
1511integer constants are allowed. When indexing into an array or pointer
1512<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
1513
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1514<p>For example, let's consider a C code fragment and how it gets
1515compiled to LLVM:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1516
1517<pre>
1518 struct RT {
1519 char A;
1520 int B[10][20];
1521 char C;
1522 };
1523 struct ST {
1524 int X;
1525 double Y;
1526 struct RT Z;
1527 };
1528
1529 int *foo(struct ST *s) {
1530 return &amp;s[1].Z.B[5][13];
1531 }
1532</pre>
1533
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1534<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1535
1536<pre>
1537 %RT = type { sbyte, [10 x [20 x int]], sbyte }
1538 %ST = type { int, double, %RT }
1539
Brian Gaeke317ef962004-07-02 21:08:14 +0000[diff] [blame]1540 implementation
1541
1542 int* %foo(%ST* %s) {
1543 entry:
1544 %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1545 ret int* %reg
1546 }
1547</pre>
1548
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1549<h5>Semantics:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1550
1551<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
Chris Lattner10ee9652004-06-03 22:57:15 +0000[diff] [blame]1552on the pointer type that is being index into. <a href="#t_pointer">Pointer</a>
1553and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
1554<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]1555types require <tt>uint</tt> <b>constants</b>.</p>
1556
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1557<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]1558type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
1559}</tt>' type, a structure. The second index indexes into the third element of
1560the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
1561sbyte }</tt>' type, another structure. The third index indexes into the second
1562element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
1563array. The two dimensions of the array are subscripted into, yielding an
1564'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction return a pointer
1565to this element, thus computing a value of '<tt>int*</tt>' type.</p>
1566
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1567<p>Note that it is perfectly legal to index partially through a
1568structure, returning a pointer to an inner element. Because of this,
1569the LLVM code for the given testcase is equivalent to:</p>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1570
1571<pre>
1572 int* "foo"(%ST* %s) {
1573 %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
1574 %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
1575 %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1576 %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
1577 %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
1578 ret int* %t5
1579 }
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1580</pre>
Chris Lattner590645f2002-04-14 06:13:44 +0000[diff] [blame]1581<h5>Example:</h5>
Chris Lattner33fd7022004-04-05 01:30:49 +0000[diff] [blame]1582<pre>
1583 <i>; yields [12 x ubyte]*:aptr</i>
1584 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
1585</pre>
1586
1587</div>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1588<!-- ======================================================================= -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1589<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1590<div class="doc_text">
John Criswell417228d2004-04-09 16:48:45 +0000[diff] [blame]1591<p>The instructions in this category are the "miscellaneous"
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1592instructions, which defy better classification.</p>
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_phi">'<tt>phi</tt>'
1596Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1597<div class="doc_text">
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]1598<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1599<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]1600<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1601<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
1602the SSA graph representing the function.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]1603<h5>Arguments:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1604<p>The type of the incoming values are specified with the first type
1605field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
1606as arguments, with one pair for each predecessor basic block of the
1607current block. Only values of <a href="#t_firstclass">first class</a>
1608type may be used as the value arguments to the PHI node. Only labels
1609may be used as the label arguments.</p>
1610<p>There must be no non-phi instructions between the start of a basic
1611block and the PHI instructions: i.e. PHI instructions must be first in
1612a basic block.</p>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]1613<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1614<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
1615value specified by the parameter, depending on which basic block we
1616came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1617<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1618<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]1619</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1620
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1621<!-- _______________________________________________________________________ -->
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1622<div class="doc_subsubsection">
1623 <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
1624</div>
1625
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1626<div class="doc_text">
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1627
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1628<h5>Syntax:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1629
1630<pre>
1631 &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]1632</pre>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1633
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1634<h5>Overview:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1635
1636<p>
1637The '<tt>cast</tt>' instruction is used as the primitive means to convert
1638integers to floating point, change data type sizes, and break type safety (by
1639casting pointers).
1640</p>
1641
1642
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1643<h5>Arguments:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1644
1645<p>
1646The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
1647class value, and a type to cast it to, which must also be a <a
1648href="#t_firstclass">first class</a> type.
1649</p>
1650
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1651<h5>Semantics:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1652
1653<p>
1654This instruction follows the C rules for explicit casts when determining how the
1655data being cast must change to fit in its new container.
1656</p>
1657
1658<p>
1659When casting to bool, any value that would be considered true in the context of
1660a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
1661all else are '<tt>false</tt>'.
1662</p>
1663
1664<p>
1665When extending an integral value from a type of one signness to another (for
1666example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
1667<b>source</b> value is signed, and zero-extended if the source value is
1668unsigned. <tt>bool</tt> values are always zero extended into either zero or
1669one.
1670</p>
1671
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]1672<h5>Example:</h5>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1673
1674<pre>
1675 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattnerd8f8ede2002-06-25 18:03:17 +0000[diff] [blame]1676 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]1677</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1678</div>
Chris Lattnerb53c28d2004-03-12 05:50:16 +0000[diff] [blame]1679
1680<!-- _______________________________________________________________________ -->
1681<div class="doc_subsubsection">
1682 <a name="i_select">'<tt>select</tt>' Instruction</a>
1683</div>
1684
1685<div class="doc_text">
1686
1687<h5>Syntax:</h5>
1688
1689<pre>
1690 &lt;result&gt; = select bool &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt; <i>; yields ty</i>
1691</pre>
1692
1693<h5>Overview:</h5>
1694
1695<p>
1696The '<tt>select</tt>' instruction is used to choose one value based on a
1697condition, without branching.
1698</p>
1699
1700
1701<h5>Arguments:</h5>
1702
1703<p>
1704The '<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.
1705</p>
1706
1707<h5>Semantics:</h5>
1708
1709<p>
1710If the boolean condition evaluates to true, the instruction returns the first
1711value argument, otherwise it returns the second value argument.
1712</p>
1713
1714<h5>Example:</h5>
1715
1716<pre>
1717 %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
1718</pre>
1719</div>
1720
1721
1722
1723
1724
Chris Lattner70de6632001-07-09 00:26:23 +0000[diff] [blame]1725<!-- _______________________________________________________________________ -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1726<div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>'
1727Instruction</a> </div>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1728<div class="doc_text">
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1729<h5>Syntax:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1730<pre> &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)<br></pre>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1731<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1732<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1733<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1734<p>This instruction requires several arguments:</p>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1735<ol>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1736 <li>
1737 <p>'<tt>ty</tt>': shall be the signature of the pointer to function
1738value being invoked. The argument types must match the types implied
1739by this signature.</p>
1740 </li>
1741 <li>
1742 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a
1743function to be invoked. In most cases, this is a direct function
1744invocation, but indirect <tt>call</tt>s are just as possible,
1745calling an arbitrary pointer to function values.</p>
1746 </li>
1747 <li>
1748 <p>'<tt>function args</tt>': argument list whose types match the
1749function signature argument types. If the function signature
1750indicates the function accepts a variable number of arguments, the
1751extra arguments can be specified.</p>
1752 </li>
Chris Lattnera8292f32002-05-06 22:08:29 +0000[diff] [blame]1753</ol>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1754<h5>Semantics:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1755<p>The '<tt>call</tt>' instruction is used to cause control flow to
1756transfer to a specified function, with its incoming arguments bound to
1757the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
1758instruction in the called function, control flow continues with the
1759instruction after the function call, and the return value of the
1760function is bound to the result argument. This is a simpler case of
1761the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]1762<h5>Example:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1763<pre> %retval = call int %test(int %argc)<br> call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<br></pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1764</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1765
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1766<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1767<div class="doc_subsubsection">
1768 <a name="i_vanext">'<tt>vanext</tt>' Instruction</a>
1769</div>
1770
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1771<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1772
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1773<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1774
1775<pre>
1776 &lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
1777</pre>
1778
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1779<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1780
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1781<p>The '<tt>vanext</tt>' instruction is used to access arguments passed
1782through the "variable argument" area of a function call. It is used to
1783implement the <tt>va_arg</tt> macro in C.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1784
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1785<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1786
1787<p>This instruction takes a <tt>va_list</tt> value and the type of the
1788argument. It returns another <tt>va_list</tt>. The actual type of
1789<tt>va_list</tt> may be defined differently for different targets. Most targets
1790use a <tt>va_list</tt> type of <tt>sbyte*</tt> or some other pointer type.</p>
1791
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1792<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1793
1794<p>The '<tt>vanext</tt>' instruction advances the specified <tt>va_list</tt>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1795past an argument of the specified type. In conjunction with the <a
1796 href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement
1797the <tt>va_arg</tt> macro available in C. For more information, see
1798the variable argument handling <a href="#int_varargs">Intrinsic
1799Functions</a>.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1800
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1801<p>It is legal for this instruction to be called in a function which
1802does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1803function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1804
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1805<p><tt>vanext</tt> is an LLVM instruction instead of an <a
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1806href="#intrinsics">intrinsic function</a> because it takes a type as an
1807argument. The type refers to the current argument in the <tt>va_list</tt>, it
1808tells the compiler how far on the stack it needs to advance to find the next
1809argument</p>
1810
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1811<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1812
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1813<p>See the <a href="#int_varargs">variable argument processing</a>
1814section.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1815
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1816</div>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1817
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]1818<!-- _______________________________________________________________________ -->
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1819<div class="doc_subsubsection">
1820 <a name="i_vaarg">'<tt>vaarg</tt>' Instruction</a>
1821</div>
1822
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1823<div class="doc_text">
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1824
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]1825<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1826
1827<pre>
1828 &lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
1829</pre>
1830
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]1831<h5>Overview:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1832
1833<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed through
1834the "variable argument" area of a function call. It is used to implement the
1835<tt>va_arg</tt> macro in C.</p>
1836
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]1837<h5>Arguments:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1838
1839<p>This instruction takes a <tt>va_list</tt> value and the type of the
1840argument. It returns a value of the specified argument type. Again, the actual
1841type of <tt>va_list</tt> is target specific.</p>
1842
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]1843<h5>Semantics:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1844
1845<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified type from
1846the specified <tt>va_list</tt>. In conjunction with the <a
1847href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to implement the
1848<tt>va_arg</tt> macro available in C. For more information, see the variable
1849argument handling <a href="#int_varargs">Intrinsic Functions</a>.</p>
1850
1851<p>It is legal for this instruction to be called in a function which does not
1852take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1853function.</p>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1854
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1855<p><tt>vaarg</tt> is an LLVM instruction instead of an <a
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1856href="#intrinsics">intrinsic function</a> because it takes an type as an
1857argument.</p>
1858
Chris Lattner26ca62e2003-10-18 05:51:36 +0000[diff] [blame]1859<h5>Example:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1860
1861<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
1862
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1863</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1864
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1865<!-- *********************************************************************** -->
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1866<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
1867<!-- *********************************************************************** -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1868
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1869<div class="doc_text">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]1870
1871<p>LLVM supports the notion of an "intrinsic function". These functions have
1872well known names and semantics, and are required to follow certain
1873restrictions. Overall, these instructions represent an extension mechanism for
1874the LLVM language that does not require changing all of the transformations in
1875LLVM to add to the language (or the bytecode reader/writer, the parser,
1876etc...).</p>
1877
1878<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix, this
1879prefix is reserved in LLVM for intrinsic names, thus functions may not be named
1880this. Intrinsic functions must always be external functions: you cannot define
1881the body of intrinsic functions. Intrinsic functions may only be used in call
1882or invoke instructions: it is illegal to take the address of an intrinsic
1883function. Additionally, because intrinsic functions are part of the LLVM
1884language, it is required that they all be documented here if any are added.</p>
1885
1886
1887<p>
1888Adding an intrinsic to LLVM is straight-forward if it is possible to express the
1889concept in LLVM directly (ie, code generator support is not _required_). To do
1890this, extend the default implementation of the IntrinsicLowering class to handle
1891the intrinsic. Code generators use this class to lower intrinsics they do not
1892understand to raw LLVM instructions that they do.
1893</p>
1894
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1895</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1896
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1897<!-- ======================================================================= -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1898<div class="doc_subsection">
1899 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
1900</div>
1901
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1902<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1903
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1904<p>Variable argument support is defined in LLVM with the <a
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1905 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
1906intrinsic functions. These functions are related to the similarly
1907named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1908
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1909<p>All of these functions operate on arguments that use a
1910target-specific value type "<tt>va_list</tt>". The LLVM assembly
1911language reference manual does not define what this type is, so all
1912transformations should be prepared to handle intrinsics with any type
1913used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1914
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1915<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1916instruction and the variable argument handling intrinsic functions are
1917used.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1918
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]1919<pre>
1920int %test(int %X, ...) {
1921 ; Initialize variable argument processing
1922 %ap = call sbyte* %<a href="#i_va_start">llvm.va_start</a>()
1923
1924 ; Read a single integer argument
1925 %tmp = vaarg sbyte* %ap, int
1926
1927 ; Advance to the next argument
1928 %ap2 = vanext sbyte* %ap, int
1929
1930 ; Demonstrate usage of llvm.va_copy and llvm.va_end
1931 %aq = call sbyte* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)
1932 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq)
1933
1934 ; Stop processing of arguments.
1935 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)
1936 ret int %tmp
1937}
1938</pre>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1939</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1940
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1941<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1942<div class="doc_subsubsection">
1943 <a name="i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
1944</div>
1945
1946
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1947<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1948<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1949<pre> call &lt;va_list&gt; ()* %llvm.va_start()<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1950<h5>Overview:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1951<p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
1952for subsequent use by the variable argument intrinsics.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1953<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1954<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]1955macro available in C. In a target-dependent way, it initializes and
1956returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt>
1957will produce the first variable argument passed to the function. Unlike
1958the C <tt>va_start</tt> macro, this intrinsic does not need to know the
1959last argument of the function, the compiler can figure that out.</p>
1960<p>Note that this intrinsic function is only legal to be called from
1961within the body of a variable argument function.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1962</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1963
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1964<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1965<div class="doc_subsubsection">
1966 <a name="i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
1967</div>
1968
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1969<div class="doc_text">
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1970<h5>Syntax:</h5>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1971<pre> call void (&lt;va_list&gt;)* %llvm.va_end(&lt;va_list&gt; &lt;arglist&gt;)<br></pre>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1972<h5>Overview:</h5>
Chris Lattner48b383b02003-11-25 01:02:51 +0000[diff] [blame]1973<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
1974which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
1975or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1976<h5>Arguments:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1977<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1978<h5>Semantics:</h5>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1979<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]1980macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
1981Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
1982 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
1983with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1984</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1985
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1986<!-- _______________________________________________________________________ -->
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]1987<div class="doc_subsubsection">
1988 <a name="i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
1989</div>
1990
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]1991<div class="doc_text">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1992
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1993<h5>Syntax:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1994
1995<pre>
Chris Lattner6a4a0492004-09-27 21:51:25 +0000[diff] [blame^]1996 call &lt;va_list&gt; (&lt;va_list&gt;)* %llvm.va_copy(&lt;va_list&gt; &lt;destarglist&gt;)
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]1997</pre>
1998
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]1999<h5>Overview:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2000
2001<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
2002from the source argument list to the destination argument list.</p>
2003
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2004<h5>Arguments:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2005
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2006<p>The argument is the <tt>va_list</tt> to copy.</p>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2007
Chris Lattnerbd64b4e2003-05-08 04:57:36 +0000[diff] [blame]2008<h5>Semantics:</h5>
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2009
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2010<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]2011macro available in C. In a target-dependent way, it copies the source
2012<tt>va_list</tt> element into the returned list. This intrinsic is necessary
Chris Lattner53e5e2a2004-06-21 22:52:48 +0000[diff] [blame]2013because 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]2014arbitrarily complex and require memory allocation, for example.</p>
2015
Misha Brukman76307852003-11-08 01:05:38 +0000[diff] [blame]2016</div>
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2017
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2018<!-- ======================================================================= -->
2019<div class="doc_subsection">
Chris Lattner757528b0b2004-05-23 21:06:01 +0000[diff] [blame]2020 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
2021</div>
2022
2023<div class="doc_text">
2024
2025<p>
2026LLVM support for <a href="GarbageCollection.html">Accurate Garbage
2027Collection</a> requires the implementation and generation of these intrinsics.
2028These intrinsics allow identification of <a href="#i_gcroot">GC roots on the
2029stack</a>, as well as garbage collector implementations that require <a
2030href="#i_gcread">read</a> and <a href="#i_gcwrite">write</a> barriers.
2031Front-ends for type-safe garbage collected languages should generate these
2032intrinsics to make use of the LLVM garbage collectors. For more details, see <a
2033href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
2034</p>
2035</div>
2036
2037<!-- _______________________________________________________________________ -->
2038<div class="doc_subsubsection">
2039 <a name="i_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
2040</div>
2041
2042<div class="doc_text">
2043
2044<h5>Syntax:</h5>
2045
2046<pre>
2047 call void (&lt;ty&gt;**, &lt;ty2&gt;*)* %llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
2048</pre>
2049
2050<h5>Overview:</h5>
2051
2052<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existance of a GC root to
2053the code generator, and allows some metadata to be associated with it.</p>
2054
2055<h5>Arguments:</h5>
2056
2057<p>The first argument specifies the address of a stack object that contains the
2058root pointer. The second pointer (which must be either a constant or a global
2059value address) contains the meta-data to be associated with the root.</p>
2060
2061<h5>Semantics:</h5>
2062
2063<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
2064location. At compile-time, the code generator generates information to allow
2065the runtime to find the pointer at GC safe points.
2066</p>
2067
2068</div>
2069
2070
2071<!-- _______________________________________________________________________ -->
2072<div class="doc_subsubsection">
2073 <a name="i_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
2074</div>
2075
2076<div class="doc_text">
2077
2078<h5>Syntax:</h5>
2079
2080<pre>
2081 call sbyte* (sbyte**)* %llvm.gcread(sbyte** %Ptr)
2082</pre>
2083
2084<h5>Overview:</h5>
2085
2086<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
2087locations, allowing garbage collector implementations that require read
2088barriers.</p>
2089
2090<h5>Arguments:</h5>
2091
2092<p>The argument is the address to read from, which should be an address
2093allocated from the garbage collector.</p>
2094
2095<h5>Semantics:</h5>
2096
2097<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
2098instruction, but may be replaced with substantially more complex code by the
2099garbage collector runtime, as needed.</p>
2100
2101</div>
2102
2103
2104<!-- _______________________________________________________________________ -->
2105<div class="doc_subsubsection">
2106 <a name="i_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
2107</div>
2108
2109<div class="doc_text">
2110
2111<h5>Syntax:</h5>
2112
2113<pre>
2114 call void (sbyte*, sbyte**)* %llvm.gcwrite(sbyte* %P1, sbyte** %P2)
2115</pre>
2116
2117<h5>Overview:</h5>
2118
2119<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
2120locations, allowing garbage collector implementations that require write
2121barriers (such as generational or reference counting collectors).</p>
2122
2123<h5>Arguments:</h5>
2124
2125<p>The first argument is the reference to store, and the second is the heap
2126location to store to.</p>
2127
2128<h5>Semantics:</h5>
2129
2130<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
2131instruction, but may be replaced with substantially more complex code by the
2132garbage collector runtime, as needed.</p>
2133
2134</div>
2135
2136
2137
2138<!-- ======================================================================= -->
2139<div class="doc_subsection">
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2140 <a name="int_codegen">Code Generator Intrinsics</a>
2141</div>
2142
2143<div class="doc_text">
2144<p>
2145These intrinsics are provided by LLVM to expose special features that may only
2146be implemented with code generator support.
2147</p>
2148
2149</div>
2150
2151<!-- _______________________________________________________________________ -->
2152<div class="doc_subsubsection">
2153 <a name="i_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
2154</div>
2155
2156<div class="doc_text">
2157
2158<h5>Syntax:</h5>
2159<pre>
2160 call void* ()* %llvm.returnaddress(uint &lt;level&gt;)
2161</pre>
2162
2163<h5>Overview:</h5>
2164
2165<p>
2166The '<tt>llvm.returnaddress</tt>' intrinsic returns a target-specific value
2167indicating the return address of the current function or one of its callers.
2168</p>
2169
2170<h5>Arguments:</h5>
2171
2172<p>
2173The argument to this intrinsic indicates which function to return the address
2174for. Zero indicates the calling function, one indicates its caller, etc. The
2175argument is <b>required</b> to be a constant integer value.
2176</p>
2177
2178<h5>Semantics:</h5>
2179
2180<p>
2181The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
2182the return address of the specified call frame, or zero if it cannot be
2183identified. The value returned by this intrinsic is likely to be incorrect or 0
2184for arguments other than zero, so it should only be used for debugging purposes.
2185</p>
2186
2187<p>
2188Note that calling this intrinsic does not prevent function inlining or other
2189aggressive transformations, so the value returned may not that of the obvious
2190source-language caller.
2191</p>
2192</div>
2193
2194
2195<!-- _______________________________________________________________________ -->
2196<div class="doc_subsubsection">
2197 <a name="i_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
2198</div>
2199
2200<div class="doc_text">
2201
2202<h5>Syntax:</h5>
2203<pre>
2204 call void* ()* %llvm.frameaddress(uint &lt;level&gt;)
2205</pre>
2206
2207<h5>Overview:</h5>
2208
2209<p>
2210The '<tt>llvm.frameaddress</tt>' intrinsic returns the target-specific frame
2211pointer value for the specified stack frame.
2212</p>
2213
2214<h5>Arguments:</h5>
2215
2216<p>
2217The argument to this intrinsic indicates which function to return the frame
2218pointer for. Zero indicates the calling function, one indicates its caller,
2219etc. The argument is <b>required</b> to be a constant integer value.
2220</p>
2221
2222<h5>Semantics:</h5>
2223
2224<p>
2225The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
2226the frame address of the specified call frame, or zero if it cannot be
2227identified. The value returned by this intrinsic is likely to be incorrect or 0
2228for arguments other than zero, so it should only be used for debugging purposes.
2229</p>
2230
2231<p>
2232Note that calling this intrinsic does not prevent function inlining or other
2233aggressive transformations, so the value returned may not that of the obvious
2234source-language caller.
2235</p>
2236</div>
2237
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2238<!-- ======================================================================= -->
2239<div class="doc_subsection">
2240 <a name="int_os">Operating System Intrinsics</a>
2241</div>
2242
2243<div class="doc_text">
2244<p>
2245These intrinsics are provided by LLVM to support the implementation of
2246operating system level code.
2247</p>
2248
2249</div>
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2250
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2251<!-- _______________________________________________________________________ -->
2252<div class="doc_subsubsection">
2253 <a name="i_readport">'<tt>llvm.readport</tt>' Intrinsic</a>
2254</div>
2255
2256<div class="doc_text">
2257
2258<h5>Syntax:</h5>
2259<pre>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2260 call &lt;integer type&gt; (&lt;integer type&gt;)* %llvm.readport (&lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2261</pre>
2262
2263<h5>Overview:</h5>
2264
2265<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2266The '<tt>llvm.readport</tt>' intrinsic reads data from the specified hardware
2267I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2268</p>
2269
2270<h5>Arguments:</h5>
2271
2272<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2273The argument to this intrinsic indicates the hardware I/O address from which
2274to read the data. The address is in the hardware I/O address namespace (as
2275opposed to being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2276</p>
2277
2278<h5>Semantics:</h5>
2279
2280<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2281The '<tt>llvm.readport</tt>' intrinsic reads data from the hardware I/O port
2282specified by <i>address</i> and returns the value. The address and return
2283value must be integers, but the size is dependent upon the platform upon which
2284the program is code generated. For example, on x86, the address must be an
2285unsigned 16 bit value, and the return value must be 8, 16, or 32 bits.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2286</p>
2287
2288</div>
2289
2290<!-- _______________________________________________________________________ -->
2291<div class="doc_subsubsection">
2292 <a name="i_writeport">'<tt>llvm.writeport</tt>' Intrinsic</a>
2293</div>
2294
2295<div class="doc_text">
2296
2297<h5>Syntax:</h5>
2298<pre>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2299 call void (&lt;integer type&gt;, &lt;integer type&gt;)* %llvm.writeport (&lt;integer type&gt; &lt;value&gt;, &lt;integer type&gt; &lt;address&gt;)
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2300</pre>
2301
2302<h5>Overview:</h5>
2303
2304<p>
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2305The '<tt>llvm.writeport</tt>' intrinsic writes data to the specified hardware
2306I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2307</p>
2308
2309<h5>Arguments:</h5>
2310
2311<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2312The first argument is the value to write to the I/O port.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2313</p>
2314
2315<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2316The second argument indicates the hardware I/O address to which data should be
2317written. The address is in the hardware I/O address namespace (as opposed to
2318being a memory location for memory mapped I/O).
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2319</p>
2320
2321<h5>Semantics:</h5>
2322
2323<p>
2324The '<tt>llvm.writeport</tt>' intrinsic writes <i>value</i> to the I/O port
2325specified by <i>address</i>. The address and value must be integers, but the
2326size is dependent upon the platform upon which the program is code generated.
John Criswellaa1c3c12004-04-09 16:43:20 +0000[diff] [blame]2327For example, on x86, the address must be an unsigned 16 bit value, and the
2328value written must be 8, 16, or 32 bits in length.
John Criswell508b93c2004-04-09 15:23:37 +0000[diff] [blame]2329</p>
2330
2331</div>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2332
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2333<!-- _______________________________________________________________________ -->
2334<div class="doc_subsubsection">
2335 <a name="i_readio">'<tt>llvm.readio</tt>' Intrinsic</a>
2336</div>
2337
2338<div class="doc_text">
2339
2340<h5>Syntax:</h5>
2341<pre>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2342 call &lt;result&gt; (&lt;ty&gt;*)* %llvm.readio (&lt;ty&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2343</pre>
2344
2345<h5>Overview:</h5>
2346
2347<p>
2348The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
2349address.
2350</p>
2351
2352<h5>Arguments:</h5>
2353
2354<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2355The argument to this intrinsic is a pointer indicating the memory address from
2356which to read the data. The data must be a
2357<a href="#t_firstclass">first class</a> type.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2358</p>
2359
2360<h5>Semantics:</h5>
2361
2362<p>
2363The '<tt>llvm.readio</tt>' intrinsic reads data from a memory mapped I/O
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2364location specified by <i>pointer</i> and returns the value. The argument must
2365be a pointer, and the return value must be a
2366<a href="#t_firstclass">first class</a> type. However, certain architectures
2367may not support I/O on all first class types. For example, 32 bit processors
2368may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2369</p>
2370
2371<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2372This intrinsic enforces an in-order memory model for llvm.readio and
2373llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2374scheduled processors may execute loads and stores out of order, re-ordering at
2375run time accesses to memory mapped I/O registers. Using these intrinsics
2376ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2377</p>
2378
2379</div>
2380
2381<!-- _______________________________________________________________________ -->
2382<div class="doc_subsubsection">
2383 <a name="i_writeio">'<tt>llvm.writeio</tt>' Intrinsic</a>
2384</div>
2385
2386<div class="doc_text">
2387
2388<h5>Syntax:</h5>
2389<pre>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2390 call void (&lt;ty1&gt;, &lt;ty2&gt;*)* %llvm.writeio (&lt;ty1&gt; &lt;value&gt;, &lt;ty2&gt; * &lt;pointer&gt;)
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2391</pre>
2392
2393<h5>Overview:</h5>
2394
2395<p>
2396The '<tt>llvm.writeio</tt>' intrinsic writes data to the specified memory
2397mapped I/O address.
2398</p>
2399
2400<h5>Arguments:</h5>
2401
2402<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2403The first argument is the value to write to the memory mapped I/O location.
2404The second argument is a pointer indicating the memory address to which the
2405data should be written.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2406</p>
2407
2408<h5>Semantics:</h5>
2409
2410<p>
2411The '<tt>llvm.writeio</tt>' intrinsic writes <i>value</i> to the memory mapped
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2412I/O address specified by <i>pointer</i>. The value must be a
2413<a href="#t_firstclass">first class</a> type. However, certain architectures
2414may not support I/O on all first class types. For example, 32 bit processors
2415may only support I/O on data types that are 32 bits or less.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2416</p>
2417
2418<p>
John Criswell7a576472004-04-12 16:33:19 +0000[diff] [blame]2419This intrinsic enforces an in-order memory model for llvm.readio and
2420llvm.writeio calls on machines that use dynamic scheduling. Dynamically
2421scheduled processors may execute loads and stores out of order, re-ordering at
2422run time accesses to memory mapped I/O registers. Using these intrinsics
2423ensures that accesses to memory mapped I/O registers occur in program order.
John Criswella4501222004-04-12 15:02:16 +0000[diff] [blame]2424</p>
2425
2426</div>
2427
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2428<!-- ======================================================================= -->
2429<div class="doc_subsection">
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2430 <a name="int_libc">Standard C Library Intrinsics</a>
2431</div>
2432
2433<div class="doc_text">
2434<p>
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2435LLVM provides intrinsics for a few important standard C library functions.
2436These intrinsics allow source-language front-ends to pass information about the
2437alignment of the pointer arguments to the code generator, providing opportunity
2438for more efficient code generation.
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2439</p>
2440
2441</div>
2442
2443<!-- _______________________________________________________________________ -->
2444<div class="doc_subsubsection">
2445 <a name="i_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
2446</div>
2447
2448<div class="doc_text">
2449
2450<h5>Syntax:</h5>
2451<pre>
2452 call void (sbyte*, sbyte*, uint, uint)* %llvm.memcpy(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
2453 uint &lt;len&gt;, uint &lt;align&gt;)
2454</pre>
2455
2456<h5>Overview:</h5>
2457
2458<p>
2459The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
2460location to the destination location.
2461</p>
2462
2463<p>
2464Note that, unlike the standard libc function, the <tt>llvm.memcpy</tt> intrinsic
2465does not return a value, and takes an extra alignment argument.
2466</p>
2467
2468<h5>Arguments:</h5>
2469
2470<p>
2471The first argument is a pointer to the destination, the second is a pointer to
2472the source. The third argument is an (arbitrarily sized) integer argument
2473specifying the number of bytes to copy, and the fourth argument is the alignment
2474of the source and destination locations.
2475</p>
2476
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]2477<p>
2478If the call to this intrinisic has an alignment value that is not 0 or 1, then
2479the caller guarantees that the size of the copy is a multiple of the alignment
2480and that both the source and destination pointers are aligned to that boundary.
2481</p>
2482
Chris Lattnerfee11462004-02-12 17:01:32 +0000[diff] [blame]2483<h5>Semantics:</h5>
2484
2485<p>
2486The '<tt>llvm.memcpy</tt>' intrinsic copies a block of memory from the source
2487location to the destination location, which are not allowed to overlap. It
2488copies "len" bytes of memory over. If the argument is known to be aligned to
2489some boundary, this can be specified as the fourth argument, otherwise it should
2490be set to 0 or 1.
2491</p>
2492</div>
2493
2494
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]2495<!-- _______________________________________________________________________ -->
2496<div class="doc_subsubsection">
2497 <a name="i_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
2498</div>
2499
2500<div class="doc_text">
2501
2502<h5>Syntax:</h5>
2503<pre>
2504 call void (sbyte*, sbyte*, uint, uint)* %llvm.memmove(sbyte* &lt;dest&gt;, sbyte* &lt;src&gt;,
2505 uint &lt;len&gt;, uint &lt;align&gt;)
2506</pre>
2507
2508<h5>Overview:</h5>
2509
2510<p>
2511The '<tt>llvm.memmove</tt>' intrinsic moves a block of memory from the source
2512location to the destination location. It is similar to the '<tt>llvm.memcpy</tt>'
2513intrinsic but allows the two memory locations to overlap.
2514</p>
2515
2516<p>
2517Note that, unlike the standard libc function, the <tt>llvm.memmove</tt> intrinsic
2518does not return a value, and takes an extra alignment argument.
2519</p>
2520
2521<h5>Arguments:</h5>
2522
2523<p>
2524The first argument is a pointer to the destination, the second is a pointer to
2525the source. The third argument is an (arbitrarily sized) integer argument
2526specifying the number of bytes to copy, and the fourth argument is the alignment
2527of the source and destination locations.
2528</p>
2529
Chris Lattner4c67c482004-02-12 21:18:15 +0000[diff] [blame]2530<p>
2531If the call to this intrinisic has an alignment value that is not 0 or 1, then
2532the caller guarantees that the size of the copy is a multiple of the alignment
2533and that both the source and destination pointers are aligned to that boundary.
2534</p>
2535
Chris Lattnerf30152e2004-02-12 18:10:10 +0000[diff] [blame]2536<h5>Semantics:</h5>
2537
2538<p>
2539The '<tt>llvm.memmove</tt>' intrinsic copies a block of memory from the source
2540location to the destination location, which may overlap. It
2541copies "len" bytes of memory over. If the argument is known to be aligned to
2542some boundary, this can be specified as the fourth argument, otherwise it should
2543be set to 0 or 1.
2544</p>
2545</div>
2546
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2547
Chris Lattner3649c3a2004-02-14 04:08:35 +0000[diff] [blame]2548<!-- _______________________________________________________________________ -->
2549<div class="doc_subsubsection">
2550 <a name="i_memset">'<tt>llvm.memset</tt>' Intrinsic</a>
2551</div>
2552
2553<div class="doc_text">
2554
2555<h5>Syntax:</h5>
2556<pre>
2557 call void (sbyte*, ubyte, uint, uint)* %llvm.memset(sbyte* &lt;dest&gt;, ubyte &lt;val&gt;,
2558 uint &lt;len&gt;, uint &lt;align&gt;)
2559</pre>
2560
2561<h5>Overview:</h5>
2562
2563<p>
2564The '<tt>llvm.memset</tt>' intrinsic fills a block of memory with a particular
2565byte value.
2566</p>
2567
2568<p>
2569Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
2570does not return a value, and takes an extra alignment argument.
2571</p>
2572
2573<h5>Arguments:</h5>
2574
2575<p>
2576The first argument is a pointer to the destination to fill, the second is the
2577byte value to fill it with, the third argument is an (arbitrarily sized) integer
2578argument specifying the number of bytes to fill, and the fourth argument is the
2579known alignment of destination location.
2580</p>
2581
2582<p>
2583If the call to this intrinisic has an alignment value that is not 0 or 1, then
2584the caller guarantees that the size of the copy is a multiple of the alignment
2585and that the destination pointer is aligned to that boundary.
2586</p>
2587
2588<h5>Semantics:</h5>
2589
2590<p>
2591The '<tt>llvm.memset</tt>' intrinsic fills "len" bytes of memory starting at the
2592destination location. If the argument is known to be aligned to some boundary,
2593this can be specified as the fourth argument, otherwise it should be set to 0 or
25941.
2595</p>
2596</div>
2597
2598
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]2599<!-- _______________________________________________________________________ -->
2600<div class="doc_subsubsection">
Alkis Evlogimenos0fa39232004-06-13 01:16:15 +0000[diff] [blame]2601 <a name="i_isunordered">'<tt>llvm.isunordered</tt>' Intrinsic</a>
2602</div>
2603
2604<div class="doc_text">
2605
2606<h5>Syntax:</h5>
2607<pre>
2608 call bool (&lt;float or double&gt;, &lt;float or double&gt;)* %llvm.isunordered(&lt;float or double&gt; Val1,
2609 &lt;float or double&gt; Val2)
2610</pre>
2611
2612<h5>Overview:</h5>
2613
2614<p>
2615The '<tt>llvm.isunordered</tt>' intrinsic returns true if either or both of the
2616specified floating point values is a NAN.
2617</p>
2618
2619<h5>Arguments:</h5>
2620
2621<p>
2622The arguments are floating point numbers of the same type.
2623</p>
2624
2625<h5>Semantics:</h5>
2626
2627<p>
2628If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise
2629false.
2630</p>
2631</div>
2632
2633
Chris Lattner3b4f4372004-06-11 02:28:03 +0000[diff] [blame]2634
2635
Chris Lattner941515c2004-01-06 05:31:32 +0000[diff] [blame]2636<!-- ======================================================================= -->
2637<div class="doc_subsection">
2638 <a name="int_debugger">Debugger Intrinsics</a>
2639</div>
2640
2641<div class="doc_text">
2642<p>
2643The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
2644are described in the <a
2645href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
2646Debugging</a> document.
2647</p>
2648</div>
2649
2650
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2651<!-- *********************************************************************** -->
Chris Lattner2f7c9632001-06-06 20:29:01 +0000[diff] [blame]2652<hr>
Misha Brukmanc501f552004-03-01 17:47:27 +0000[diff] [blame]2653<address>
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2659 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
2660 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
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