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3<head>
4 <title>LLVM Assembly Language Reference Manual</title>
5 <link rel="stylesheet" href="llvm.css" type="text/css">
6</head>
7<body>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]8<div class="doc_title"> LLVM Language Reference Manual </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]9<ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]10 <li><a href="#abstract">Abstract</a></li>
11 <li><a href="#introduction">Introduction</a></li>
12 <li><a href="#identifiers">Identifiers</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]13 <li><a href="#typesystem">Type System</a>
14 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]15 <li><a href="#t_primitive">Primitive Types</a>
16 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]17 <li><a href="#t_classifications">Type Classifications</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]18 </ol>
19 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]20 <li><a href="#t_derived">Derived Types</a>
21 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]22 <li><a href="#t_array">Array Type</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]23 <li><a href="#t_function">Function Type</a></li>
24 <li><a href="#t_pointer">Pointer Type</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]25 <li><a href="#t_struct">Structure Type</a></li>
26<!-- <li><a href="#t_packed" >Packed Type</a> -->
27 </ol>
28 </li>
29 </ol>
30 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]31 <li><a href="#highlevel">High Level Structure</a>
32 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]33 <li><a href="#modulestructure">Module Structure</a></li>
34 <li><a href="#globalvars">Global Variables</a></li>
35 <li><a href="#functionstructure">Function Structure</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]36 </ol>
37 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]38 <li><a href="#instref">Instruction Reference</a>
39 <ol>
40 <li><a href="#terminators">Terminator Instructions</a>
41 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]42 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
43 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]44 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
45 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]46 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
47 </ol>
48 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]49 <li><a href="#binaryops">Binary Operations</a>
50 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]51 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
52 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
53 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
54 <li><a href="#i_div">'<tt>div</tt>' Instruction</a></li>
55 <li><a href="#i_rem">'<tt>rem</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]56 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]57 </ol>
58 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]59 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
60 <ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]61 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]62 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]63 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
64 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
65 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]66 </ol>
67 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]68 <li><a href="#memoryops">Memory Access Operations</a>
69 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]70 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
71 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
72 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
73 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
74 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
75 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
76 </ol>
77 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]78 <li><a href="#otherops">Other Operations</a>
79 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]80 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]81 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]82 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]83 <li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a></li>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]84 <li><a href="#i_vaarg">'<tt>vaarg</tt>' Instruction</a></li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]85 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]86 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]87 </ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]88 </li>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]89 <li><a href="#intrinsics">Intrinsic Functions</a>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]90 <ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]91 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
92 <ol>
93 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
94 <li><a href="#i_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
95 <li><a href="#i_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
96 </ol>
97 </li>
98 </ol>
99 </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]100</ol>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]101<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]102<p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
103and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></b></p>
104<p> </p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]105</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]106<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]107<div class="doc_section"> <a name="abstract">Abstract </a></div>
108<!-- *********************************************************************** -->
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]109<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]110<p>This document is a reference manual for the LLVM assembly language.
111LLVM is an SSA based representation that provides type safety,
112low-level operations, flexibility, and the capability of representing
113'all' high-level languages cleanly. It is the common code
114representation used throughout all phases of the LLVM compilation
115strategy.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]116</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]117<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]118<div class="doc_section"> <a name="introduction">Introduction</a> </div>
119<!-- *********************************************************************** -->
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]120<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]121<p>The LLVM code representation is designed to be used in three
122different forms: as an in-memory compiler IR, as an on-disk bytecode
123representation (suitable for fast loading by a Just-In-Time compiler),
124and as a human readable assembly language representation. This allows
125LLVM to provide a powerful intermediate representation for efficient
126compiler transformations and analysis, while providing a natural means
127to debug and visualize the transformations. The three different forms
128of LLVM are all equivalent. This document describes the human readable
129representation and notation.</p>
130<p>The LLVM representation aims to be a light-weight and low-level
131while being expressive, typed, and extensible at the same time. It
132aims to be a "universal IR" of sorts, by being at a low enough level
133that high-level ideas may be cleanly mapped to it (similar to how
134microprocessors are "universal IR's", allowing many source languages to
135be mapped to them). By providing type information, LLVM can be used as
136the target of optimizations: for example, through pointer analysis, it
137can be proven that a C automatic variable is never accessed outside of
138the current function... allowing it to be promoted to a simple SSA
139value instead of a memory location.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]140</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]141<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]142<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]143<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]144<p>It is important to note that this document describes 'well formed'
145LLVM assembly language. There is a difference between what the parser
146accepts and what is considered 'well formed'. For example, the
147following instruction is syntactically okay, but not well formed:</p>
148<pre> %x = <a href="#i_add">add</a> int 1, %x<br></pre>
149<p>...because the definition of <tt>%x</tt> does not dominate all of
150its uses. The LLVM infrastructure provides a verification pass that may
151be used to verify that an LLVM module is well formed. This pass is
152automatically run by the parser after parsing input assembly, and by
153the optimizer before it outputs bytecode. The violations pointed out
154by the verifier pass indicate bugs in transformation passes or input to
155the parser.</p>
156<!-- Describe the typesetting conventions here. --> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]157<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]158<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]159<!-- *********************************************************************** -->
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]160<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]161<p>LLVM uses three different forms of identifiers, for different
162purposes:</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]163<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]164 <li>Numeric constants are represented as you would expect: 12, -3
165123.421, etc. Floating point constants have an optional hexidecimal
166notation.</li>
167 <li>Named values are represented as a string of characters with a '%'
168prefix. For example, %foo, %DivisionByZero,
169%a.really.long.identifier. The actual regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
170Identifiers which require other characters in their names can be
171surrounded with quotes. In this way, anything except a <tt>"</tt>
172character can be used in a name.</li>
173 <li>Unnamed values are represented as an unsigned numeric value with
174a '%' prefix. For example, %12, %2, %44.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]175</ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]176<p>LLVM requires the values start with a '%' sign for two reasons:
177Compilers don't need to worry about name clashes with reserved words,
178and the set of reserved words may be expanded in the future without
179penalty. Additionally, unnamed identifiers allow a compiler to quickly
180come up with a temporary variable without having to avoid symbol table
181conflicts.</p>
182<p>Reserved words in LLVM are very similar to reserved words in other
183languages. There are keywords for different opcodes ('<tt><a
184 href="#i_add">add</a></tt>', '<tt><a href="#i_cast">cast</a></tt>', '<tt><a
185 href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
186 href="#t_void">void</a></tt>', '<tt><a href="#t_uint">uint</a></tt>',
187etc...), and others. These reserved words cannot conflict with
188variable names, because none of them start with a '%' character.</p>
189<p>Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>'
190by 8:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]191<p>The easy way:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]192<pre> %result = <a href="#i_mul">mul</a> uint %X, 8<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]193<p>After strength reduction:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]194<pre> %result = <a href="#i_shl">shl</a> uint %X, ubyte 3<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]195<p>And the hard way:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]196<pre> <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
197 <a
198 href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
199 %result = <a
200 href="#i_add">add</a> uint %1, %1<br></pre>
201<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
202important lexical features of LLVM:</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]203<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]204 <li>Comments are delimited with a '<tt>;</tt>' and go until the end
205of line.</li>
206 <li>Unnamed temporaries are created when the result of a computation
207is not assigned to a named value.</li>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]208 <li>Unnamed temporaries are numbered sequentially</li>
209</ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]210<p>...and it also show a convention that we follow in this document.
211When demonstrating instructions, we will follow an instruction with a
212comment that defines the type and name of value produced. Comments are
213shown in italic text.</p>
214<p>The one non-intuitive notation for constants is the optional
215hexidecimal form of floating point constants. For example, the form '<tt>double
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]2160x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]2174.5e+15</tt>' which is also supported by the parser. The only time
218hexadecimal floating point constants are useful (and the only time that
219they are generated by the disassembler) is when an FP constant has to
220be emitted that is not representable as a decimal floating point number
221exactly. For example, NaN's, infinities, and other special cases are
222represented in their IEEE hexadecimal format so that assembly and
223disassembly do not cause any bits to change in the constants.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]224</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]225<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]226<div class="doc_section"> <a name="typesystem">Type System</a> </div>
227<!-- *********************************************************************** -->
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]228<div class="doc_text">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]229<p>The LLVM type system is one of the most important features of the
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]230intermediate representation. Being typed enables a number of
231optimizations to be performed on the IR directly, without having to do
232extra analyses on the side before the transformation. A strong type
233system makes it easier to read the generated code and enables novel
234analyses and transformations that are not feasible to perform on normal
235three address code representations.</p>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]236<!-- The written form for the type system was heavily influenced by the
237syntactic problems with types in the C language<sup><a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]238href="#rw_stroustrup">1</a></sup>.<p> --> </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]239<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]240<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]241<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]242<p>The primitive types are the fundemental building blocks of the LLVM
243system. The current set of primitive types are as follows:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]244<p>
245<table border="0" align="center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]246 <tbody>
247 <tr>
248 <td>
249 <table border="1" cellspacing="0" cellpadding="4" align="center">
250 <tbody>
251 <tr>
252 <td><tt>void</tt></td>
253 <td>No value</td>
254 </tr>
255 <tr>
256 <td><tt>ubyte</tt></td>
257 <td>Unsigned 8 bit value</td>
258 </tr>
259 <tr>
260 <td><tt>ushort</tt></td>
261 <td>Unsigned 16 bit value</td>
262 </tr>
263 <tr>
264 <td><tt>uint</tt></td>
265 <td>Unsigned 32 bit value</td>
266 </tr>
267 <tr>
268 <td><tt>ulong</tt></td>
269 <td>Unsigned 64 bit value</td>
270 </tr>
271 <tr>
272 <td><tt>float</tt></td>
273 <td>32 bit floating point value</td>
274 </tr>
275 <tr>
276 <td><tt>label</tt></td>
277 <td>Branch destination</td>
278 </tr>
279 </tbody>
280 </table>
281 </td>
282 <td valign="top">
283 <table border="1" cellspacing="0" cellpadding="4" align="center&quot;">
284 <tbody>
285 <tr>
286 <td><tt>bool</tt></td>
287 <td>True or False value</td>
288 </tr>
289 <tr>
290 <td><tt>sbyte</tt></td>
291 <td>Signed 8 bit value</td>
292 </tr>
293 <tr>
294 <td><tt>short</tt></td>
295 <td>Signed 16 bit value</td>
296 </tr>
297 <tr>
298 <td><tt>int</tt></td>
299 <td>Signed 32 bit value</td>
300 </tr>
301 <tr>
302 <td><tt>long</tt></td>
303 <td>Signed 64 bit value</td>
304 </tr>
305 <tr>
306 <td><tt>double</tt></td>
307 <td>64 bit floating point value</td>
308 </tr>
309 </tbody>
310 </table>
311 </td>
312 </tr>
313 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]314</table>
315</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]316</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]317<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]318<div class="doc_subsubsection"> <a name="t_classifications">Type
319Classifications</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]320<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]321<p>These different primitive types fall into a few useful
322classifications:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]323<p>
324<table border="1" cellspacing="0" cellpadding="4" align="center">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]325 <tbody>
326 <tr>
327 <td><a name="t_signed">signed</a></td>
328 <td><tt>sbyte, short, int, long, float, double</tt></td>
329 </tr>
330 <tr>
331 <td><a name="t_unsigned">unsigned</a></td>
332 <td><tt>ubyte, ushort, uint, ulong</tt></td>
333 </tr>
334 <tr>
335 <td><a name="t_integer">integer</a></td>
336 <td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
337 </tr>
338 <tr>
339 <td><a name="t_integral">integral</a></td>
340 <td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td>
341 </tr>
342 <tr>
343 <td><a name="t_floating">floating point</a></td>
344 <td><tt>float, double</tt></td>
345 </tr>
346 <tr>
347 <td><a name="t_firstclass">first class</a></td>
348 <td><tt>bool, ubyte, sbyte, ushort, short,<br>
349uint, int, ulong, long, float, double, <a href="#t_pointer">pointer</a></tt></td>
350 </tr>
351 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]352</table>
353</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]354<p>The <a href="#t_firstclass">first class</a> types are perhaps the
355most important. Values of these types are the only ones which can be
356produced by instructions, passed as arguments, or used as operands to
357instructions. This means that all structures and arrays must be
358manipulated either by pointer or by component.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]359</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]360<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]361<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]362<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]363<p>The real power in LLVM comes from the derived types in the system.
364This is what allows a programmer to represent arrays, functions,
365pointers, and other useful types. Note that these derived types may be
366recursive: For example, it is possible to have a two dimensional array.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]367</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]368<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]369<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]370<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]371<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]372<p>The array type is a very simple derived type that arranges elements
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]373sequentially in memory. The array type requires a size (number of
374elements) and an underlying data type.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]375<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]376<pre> [&lt;# elements&gt; x &lt;elementtype&gt;]<br></pre>
377<p>The number of elements is a constant integer value, elementtype may
378be any type with a size.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]379<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]380<p> <tt>[40 x int ]</tt>: Array of 40 integer values.<br>
381<tt>[41 x int ]</tt>: Array of 41 integer values.<br>
382<tt>[40 x uint]</tt>: Array of 40 unsigned integer values.</p>
383<p> </p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]384<p>Here are some examples of multidimensional arrays:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]385<p>
386<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]387 <tbody>
388 <tr>
389 <td><tt>[3 x [4 x int]]</tt></td>
390 <td>: 3x4 array integer values.</td>
391 </tr>
392 <tr>
393 <td><tt>[12 x [10 x float]]</tt></td>
394 <td>: 12x10 array of single precision floating point values.</td>
395 </tr>
396 <tr>
397 <td><tt>[2 x [3 x [4 x uint]]]</tt></td>
398 <td>: 2x3x4 array of unsigned integer values.</td>
399 </tr>
400 </tbody>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]401</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]402</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]403</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]404<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]405<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]406<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]407<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]408<p>The function type can be thought of as a function signature. It
409consists of a return type and a list of formal parameter types.
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame^]410Function types are usually used to build virtual function tables
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]411(which are structures of pointers to functions), for indirect function
412calls, and when defining a function.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame^]413<p>
414The return type of a function type cannot be an aggregate type.
415</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]416<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]417<pre> &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
418<p>Where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of
419type specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]420which indicates that the function takes a variable number of arguments.
421Variable argument functions can access their arguments with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]422 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]423<h5>Examples:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]424<p>
425<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]426 <tbody>
427 <tr>
428 <td><tt>int (int)</tt></td>
429 <td>: function taking an <tt>int</tt>, returning an <tt>int</tt></td>
430 </tr>
431 <tr>
432 <td><tt>float (int, int *) *</tt></td>
433 <td>: <a href="#t_pointer">Pointer</a> to a function that takes
434an <tt>int</tt> and a <a href="#t_pointer">pointer</a> to <tt>int</tt>,
435returning <tt>float</tt>.</td>
436 </tr>
437 <tr>
438 <td><tt>int (sbyte *, ...)</tt></td>
439 <td>: A vararg function that takes at least one <a
440 href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C),
441which returns an integer. This is the signature for <tt>printf</tt>
442in LLVM.</td>
443 </tr>
444 </tbody>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]445</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]446</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]447</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]448<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]449<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]450<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]451<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]452<p>The structure type is used to represent a collection of data members
453together in memory. The packing of the field types is defined to match
454the ABI of the underlying processor. The elements of a structure may
455be any type that has a size.</p>
456<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
457and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
458field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
459instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]460<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]461<pre> { &lt;type list&gt; }<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]462<h5>Examples:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]463<p>
464<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]465 <tbody>
466 <tr>
467 <td><tt>{ int, int, int }</tt></td>
468 <td>: a triple of three <tt>int</tt> values</td>
469 </tr>
470 <tr>
471 <td><tt>{ float, int (int) * }</tt></td>
472 <td>: A pair, where the first element is a <tt>float</tt> and the
473second element is a <a href="#t_pointer">pointer</a> to a <a
474 href="t_function">function</a> that takes an <tt>int</tt>, returning
475an <tt>int</tt>.</td>
476 </tr>
477 </tbody>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]478</table>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]479</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]480</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]481<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]482<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]483<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]484<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]485<p>As in many languages, the pointer type represents a pointer or
486reference to another object, which must live in memory.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]487<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]488<pre> &lt;type&gt; *<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]489<h5>Examples:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]490<p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]491<table border="0" cellpadding="0" cellspacing="0">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]492 <tbody>
493 <tr>
494 <td><tt>[4x int]*</tt></td>
495 <td>: <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a>
496of four <tt>int</tt> values</td>
497 </tr>
498 <tr>
499 <td><tt>int (int *) *</tt></td>
500 <td>: A <a href="#t_pointer">pointer</a> to a <a
501 href="t_function">function</a> that takes an <tt>int</tt>, returning
502an <tt>int</tt>.</td>
503 </tr>
504 </tbody>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]505</table>
506</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]507</div>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]508<!-- _______________________________________________________________________ --><!--
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]509<div class="doc_subsubsection">
510 <a name="t_packed">Packed Type</a>
511</div>
512
513<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]514
515Mention/decide that packed types work with saturation or not. Maybe have a packed+saturated type in addition to just a packed type.<p>
516
517Packed types should be 'nonsaturated' because standard data types are not saturated. Maybe have a saturated packed type?<p>
518
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]519</div>
520
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]521--><!-- *********************************************************************** -->
522<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
523<!-- *********************************************************************** --><!-- ======================================================================= -->
524<div class="doc_subsection"> <a name="modulestructure">Module Structure</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]525<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]526<p>LLVM programs are composed of "Module"s, each of which is a
527translation unit of the input programs. Each module consists of
528functions, global variables, and symbol table entries. Modules may be
529combined together with the LLVM linker, which merges function (and
530global variable) definitions, resolves forward declarations, and merges
531symbol table entries. Here is an example of the "hello world" module:</p>
532<pre><i>; Declare the string constant as a global constant...</i>
533<a href="#identifiers">%.LC0</a> = <a href="#linkage_internal">internal</a> <a
534 href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]535
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]536<i>; External declaration of the puts function</i>
537<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]538
539<i>; Definition of main function</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]540int %main() { <i>; int()* </i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]541 <i>; Convert [13x sbyte]* to sbyte *...</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]542 %cast210 = <a
543 href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]544
545 <i>; Call puts function to write out the string to stdout...</i>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]546 <a
547 href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
548 <a
549 href="#i_ret">ret</a> int 0<br>}<br></pre>
550<p>This example is made up of a <a href="#globalvars">global variable</a>
551named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
552function, and a <a href="#functionstructure">function definition</a>
553for "<tt>main</tt>".</p>
554<a name="linkage"> In general, a module is made up of a list of global
555values, where both functions and global variables are global values.
556Global values are represented by a pointer to a memory location (in
557this case, a pointer to an array of char, and a pointer to a function),
558and have one of the following linkage types:</a>
559<p> </p>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]560<dl>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]561 <a name="linkage_internal"> <dt><tt><b>internal</b></tt> </dt>
562 <dd>Global values with internal linkage are only directly accessible
563by objects in the current module. In particular, linking code into a
564module with an internal global value may cause the internal to be
565renamed as necessary to avoid collisions. Because the symbol is
566internal to the module, all references can be updated. This
567corresponds to the notion of the '<tt>static</tt>' keyword in C, or the
568idea of "anonymous namespaces" in C++.
569 <p> </p>
570 </dd>
571 </a><a name="linkage_linkonce"> <dt><tt><b>linkonce</b></tt>: </dt>
572 <dd>"<tt>linkonce</tt>" linkage is similar to <tt>internal</tt>
573linkage, with the twist that linking together two modules defining the
574same <tt>linkonce</tt> globals will cause one of the globals to be
575discarded. This is typically used to implement inline functions.
576Unreferenced <tt>linkonce</tt> globals are allowed to be discarded.
577 <p> </p>
578 </dd>
579 </a><a name="linkage_weak"> <dt><tt><b>weak</b></tt>: </dt>
580 <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt>
581linkage, except that unreferenced <tt>weak</tt> globals may not be
582discarded. This is used to implement constructs in C such as "<tt>int
583X;</tt>" at global scope.
584 <p> </p>
585 </dd>
586 </a><a name="linkage_appending"> <dt><tt><b>appending</b></tt>: </dt>
587 <dd>"<tt>appending</tt>" linkage may only be applied to global
588variables of pointer to array type. When two global variables with
589appending linkage are linked together, the two global arrays are
590appended together. This is the LLVM, typesafe, equivalent of having
591the system linker append together "sections" with identical names when
592.o files are linked.
593 <p> </p>
594 </dd>
595 </a><a name="linkage_external"> <dt><tt><b>externally visible</b></tt>:</dt>
596 <dd>If none of the above identifiers are used, the global is
597externally visible, meaning that it participates in linkage and can be
598used to resolve external symbol references.
599 <p> </p>
600 </dd>
601 </a>
602</dl>
603<p> </p>
604<p><a name="linkage_external">For example, since the "<tt>.LC0</tt>"
605variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
606variable and was linked with this one, one of the two would be renamed,
607preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
608external (i.e., lacking any linkage declarations), they are accessible
609outside of the current module. It is illegal for a function <i>declaration</i>
610to have any linkage type other than "externally visible".</a></p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]611</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]612<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]613<div class="doc_subsection"> <a name="globalvars">Global Variables</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]614<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]615<p>Global variables define regions of memory allocated at compilation
616time instead of run-time. Global variables may optionally be
617initialized. A variable may be defined as a global "constant", which
618indicates that the contents of the variable will never be modified
619(opening options for optimization). Constants must always have an
620initial value.</p>
621<p>As SSA values, global variables define pointer values that are in
622scope (i.e. they dominate) for all basic blocks in the program. Global
623variables always define a pointer to their "content" type because they
624describe a region of memory, and all memory objects in LLVM are
625accessed through pointers.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]626</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]627<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]628<div class="doc_subsection"> <a name="functionstructure">Functions</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]629<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]630<p>LLVM function definitions are composed of a (possibly empty)
631argument list, an opening curly brace, a list of basic blocks, and a
632closing curly brace. LLVM function declarations are defined with the "<tt>declare</tt>"
633keyword, a function name, and a function signature.</p>
634<p>A function definition contains a list of basic blocks, forming the
635CFG for the function. Each basic block may optionally start with a
636label (giving the basic block a symbol table entry), contains a list of
637instructions, and ends with a <a href="#terminators">terminator</a>
638instruction (such as a branch or function return).</p>
639<p>The first basic block in program is special in two ways: it is
640immediately executed on entrance to the function, and it is not allowed
641to have predecessor basic blocks (i.e. there can not be any branches to
642the entry block of a function). Because the block can have no
643predecessors, it also cannot have any <a href="#i_phi">PHI nodes</a>.</p>
John Criswell009900b2003-11-25 21:45:46 +0000[diff] [blame^]644<p>
645LLVM functions are identified by their name and type signature. Hence, two
646functions with the same name but different parameter lists or return values
647are considered different functions, and LLVM will resolves references to each
648appropriately.
649</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]650</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]651<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]652<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
653<!-- *********************************************************************** -->
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]654<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]655<p>The LLVM instruction set consists of several different
656classifications of instructions: <a href="#terminators">terminator
657instructions</a>, <a href="#binaryops">binary instructions</a>, <a
658 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
659instructions</a>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]660</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]661<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]662<div class="doc_subsection"> <a name="terminators">Terminator
663Instructions</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]664<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]665<p>As mentioned <a href="#functionstructure">previously</a>, every
666basic block in a program ends with a "Terminator" instruction, which
667indicates which block should be executed after the current block is
668finished. These terminator instructions typically yield a '<tt>void</tt>'
669value: they produce control flow, not values (the one exception being
670the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]671<p>There are five different terminator instructions: the '<a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]672 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
673instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
674the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, and the '<a
675 href="#i_unwind"><tt>unwind</tt></a>' instruction.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]676</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]677<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]678<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
679Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]680<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]681<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]682<pre> ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]683 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]684</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]685<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]686<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
687value) from a function, back to the caller.</p>
688<p>There are two forms of the '<tt>ret</tt>' instructruction: one that
689returns a value and then causes control flow, and one that just causes
690control flow to occur.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]691<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]692<p>The '<tt>ret</tt>' instruction may return any '<a
693 href="#t_firstclass">first class</a>' type. Notice that a function is
694not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
695instruction inside of the function that returns a value that does not
696match the return type of the function.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]697<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]698<p>When the '<tt>ret</tt>' instruction is executed, control flow
699returns back to the calling function's context. If the caller is a "<a
700 href="#i_call"><tt>call</tt></a> instruction, execution continues at
701the instruction after the call. If the caller was an "<a
702 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
703at the beginning "normal" of the destination block. If the instruction
704returns a value, that value shall set the call or invoke instruction's
705return value.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]706<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]707<pre> ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]708 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]709</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]710</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]711<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]712<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]713<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]714<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]715<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 Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]716</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]717<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]718<p>The '<tt>br</tt>' instruction is used to cause control flow to
719transfer to a different basic block in the current function. There are
720two forms of this instruction, corresponding to a conditional branch
721and an unconditional branch.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]722<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]723<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
724single '<tt>bool</tt>' value and two '<tt>label</tt>' values. The
725unconditional form of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>'
726value as a target.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]727<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]728<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
729argument is evaluated. If the value is <tt>true</tt>, control flows
730to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
731control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]732<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]733<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
734 href="#i_ret">ret</a> int 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> int 0<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]735</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]736<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]737<div class="doc_subsubsection"> <a name="i_switch">'<tt>switch</tt>'
738Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]739<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]740<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]741<pre> switch uint &lt;value&gt;, label &lt;defaultdest&gt; [ int &lt;val&gt;, label &amp;dest&gt;, ... ]<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]742<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]743<p>The '<tt>switch</tt>' instruction is used to transfer control flow
744to one of several different places. It is a generalization of the '<tt>br</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]745instruction, allowing a branch to occur to one of many possible
746destinations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]747<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]748<p>The '<tt>switch</tt>' instruction uses three parameters: a '<tt>uint</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]749comparison value '<tt>value</tt>', a default '<tt>label</tt>'
750destination, and an array of pairs of comparison value constants and '<tt>label</tt>'s.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]751<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]752<p>The <tt>switch</tt> instruction specifies a table of values and
753destinations. When the '<tt>switch</tt>' instruction is executed, this
754table is searched for the given value. If the value is found, the
755corresponding destination is branched to, otherwise the default value
756it transfered to.</p>
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]757<h5>Implementation:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]758<p>Depending on properties of the target machine and the particular <tt>switch</tt>
759instruction, this instruction may be code generated as a series of
760chained conditional branches, or with a lookup table.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]761<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]762<pre> <i>; Emulate a conditional br instruction</i>
763 %Val = <a
764 href="#i_cast">cast</a> bool %value to uint<br> switch uint %Val, label %truedest [int 0, label %falsedest ]<br><br> <i>; Emulate an unconditional br instruction</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]765 switch uint 0, label %dest [ ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]766
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]767 <i>; Implement a jump table:</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]768 switch uint %val, label %otherwise [ int 0, label %onzero,
769 int 1, label %onone,
770 int 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]771</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]772</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]773<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]774<div class="doc_subsubsection"> <a name="i_invoke">'<tt>invoke</tt>'
775Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]776<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]777<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]778<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 Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]779<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]780<p>The '<tt>invoke</tt>' instruction causes control to transfer to a
781specified function, with the possibility of control flow transfer to
782either the '<tt>normal</tt>' <tt>label</tt> label or the '<tt>exception</tt>'<tt>label</tt>.
783If the callee function returns with the "<tt><a href="#i_ret">ret</a></tt>"
784instruction, control flow will return to the "normal" label. If the
785callee (or any indirect callees) returns with the "<a href="#i_unwind"><tt>unwind</tt></a>"
786instruction, control is interrupted, and continued at the dynamically
787nearest "except" label.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]788<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]789<p>This instruction requires several arguments:</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]790<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]791 <li>'<tt>ptr to function ty</tt>': shall be the signature of the
792pointer to function value being invoked. In most cases, this is a
793direct function invocation, but indirect <tt>invoke</tt>s are just as
794possible, branching off an arbitrary pointer to function value. </li>
795 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer
796to a function to be invoked. </li>
797 <li>'<tt>function args</tt>': argument list whose types match the
798function signature argument types. If the function signature indicates
799the function accepts a variable number of arguments, the extra
800arguments can be specified. </li>
801 <li>'<tt>normal label</tt>': the label reached when the called
802function executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
803 <li>'<tt>exception label</tt>': the label reached when a callee
804returns with the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]805</ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]806<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]807<p>This instruction is designed to operate as a standard '<tt><a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]808 href="#i_call">call</a></tt>' instruction in most regards. The
809primary difference is that it establishes an association with a label,
810which is used by the runtime library to unwind the stack.</p>
811<p>This instruction is used in languages with destructors to ensure
812that proper cleanup is performed in the case of either a <tt>longjmp</tt>
813or a thrown exception. Additionally, this is important for
814implementation of '<tt>catch</tt>' clauses in high-level languages that
815support them.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]816<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]817<pre> %retval = invoke int %Test(int 15)<br> to label %Continue<br> except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]818</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]819</div>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]820<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]821<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
822Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]823<div class="doc_text">
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]824<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]825<pre> unwind<br></pre>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]826<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]827<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing
828control flow at the first callee in the dynamic call stack which used
829an <a href="#i_invoke"><tt>invoke</tt></a> instruction to perform the
830call. This is primarily used to implement exception handling.</p>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]831<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]832<p>The '<tt>unwind</tt>' intrinsic causes execution of the current
833function to immediately halt. The dynamic call stack is then searched
834for the first <a href="#i_invoke"><tt>invoke</tt></a> instruction on
835the call stack. Once found, execution continues at the "exceptional"
836destination block specified by the <tt>invoke</tt> instruction. If
837there is no <tt>invoke</tt> instruction in the dynamic call chain,
838undefined behavior results.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]839</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]840<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]841<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]842<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]843<p>Binary operators are used to do most of the computation in a
844program. They require two operands, execute an operation on them, and
845produce a single value. The result value of a binary operator is not
846necessarily the same type as its operands.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]847<p>There are several different binary operators:</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]848</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]849<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]850<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
851Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]852<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]853<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]854<pre> &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]855</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]856<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]857<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]858<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]859<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]860 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
861values. Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]862<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]863<p>The value produced is the integer or floating point sum of the two
864operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]865<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]866<pre> &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]867</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]868</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]869<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]870<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
871Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]872<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]873<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]874<pre> &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]875</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]876<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]877<p>The '<tt>sub</tt>' instruction returns the difference of its two
878operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]879<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
880instruction present in most other intermediate representations.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]881<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]882<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]883 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
884values. Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]885<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]886<p>The value produced is the integer or floating point difference of
887the two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]888<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]889<pre> &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]890 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
891</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]892</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]893<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]894<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
895Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]896<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]897<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]898<pre> &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]899</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]900<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]901<p>The '<tt>mul</tt>' instruction returns the product of its two
902operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]903<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]904<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]905 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
906values. Both arguments must have identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]907<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]908<p>The value produced is the integer or floating point product of the
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]909two operands.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]910<p>There is no signed vs unsigned multiplication. The appropriate
911action is taken based on the type of the operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]912<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]913<pre> &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]914</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]915</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]916<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]917<div class="doc_subsubsection"> <a name="i_div">'<tt>div</tt>'
918Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]919<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]920<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]921<pre> &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
922</pre>
923<h5>Overview:</h5>
924<p>The '<tt>div</tt>' instruction returns the quotient of its two
925operands.</p>
926<h5>Arguments:</h5>
927<p>The two arguments to the '<tt>div</tt>' instruction must be either <a
928 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
929values. Both arguments must have identical types.</p>
930<h5>Semantics:</h5>
931<p>The value produced is the integer or floating point quotient of the
932two operands.</p>
933<h5>Example:</h5>
934<pre> &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
935</pre>
936</div>
937<!-- _______________________________________________________________________ -->
938<div class="doc_subsubsection"> <a name="i_rem">'<tt>rem</tt>'
939Instruction</a> </div>
940<div class="doc_text">
941<h5>Syntax:</h5>
942<pre> &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
943</pre>
944<h5>Overview:</h5>
945<p>The '<tt>rem</tt>' instruction returns the remainder from the
946division of its two operands.</p>
947<h5>Arguments:</h5>
948<p>The two arguments to the '<tt>rem</tt>' instruction must be either <a
949 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
950values. Both arguments must have identical types.</p>
951<h5>Semantics:</h5>
952<p>This returns the <i>remainder</i> of a division (where the result
953has the same sign as the divisor), not the <i>modulus</i> (where the
954result has the same sign as the dividend) of a value. For more
955information about the difference, see: <a
956 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
957Math Forum</a>.</p>
958<h5>Example:</h5>
959<pre> &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
960</pre>
961</div>
962<!-- _______________________________________________________________________ -->
963<div class="doc_subsubsection"> <a name="i_setcc">'<tt>set<i>cc</i></tt>'
964Instructions</a> </div>
965<div class="doc_text">
966<h5>Syntax:</h5>
967<pre> &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]968 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
969 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
970 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
971 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
972 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
973</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]974<h5>Overview:</h5>
975<p>The '<tt>set<i>cc</i></tt>' family of instructions returns a boolean
976value based on a comparison of their two operands.</p>
977<h5>Arguments:</h5>
978<p>The two arguments to the '<tt>set<i>cc</i></tt>' instructions must
979be of <a href="#t_firstclass">first class</a> type (it is not possible
980to compare '<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>'
981or '<tt>void</tt>' values, etc...). Both arguments must have identical
982types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]983<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]984<p>The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
985value if both operands are equal.<br>
986The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
987value if both operands are unequal.<br>
988The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
989value if the first operand is less than the second operand.<br>
990The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
991value if the first operand is greater than the second operand.<br>
992The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
993value if the first operand is less than or equal to the second operand.<br>
994The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>'
995value if the first operand is greater than or equal to the second
996operand.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]997<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]998<pre> &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]999 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1000 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1001 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1002 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1003 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1004</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1005</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1006<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1007<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
1008Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1009<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1010<p>Bitwise binary operators are used to do various forms of
1011bit-twiddling in a program. They are generally very efficient
1012instructions, and can commonly be strength reduced from other
1013instructions. They require two operands, execute an operation on them,
1014and produce a single value. The resulting value of the bitwise binary
1015operators is always the same type as its first operand.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1016</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1017<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1018<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
1019Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1020<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1021<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1022<pre> &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1023</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1024<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1025<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
1026its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1027<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1028<p>The two arguments to the '<tt>and</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1029 href="#t_integral">integral</a> values. Both arguments must have
1030identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1031<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1032<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1033<p> </p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1034<center>
1035<table border="1" cellspacing="0" cellpadding="4">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1036 <tbody>
1037 <tr>
1038 <td>In0</td>
1039 <td>In1</td>
1040 <td>Out</td>
1041 </tr>
1042 <tr>
1043 <td>0</td>
1044 <td>0</td>
1045 <td>0</td>
1046 </tr>
1047 <tr>
1048 <td>0</td>
1049 <td>1</td>
1050 <td>0</td>
1051 </tr>
1052 <tr>
1053 <td>1</td>
1054 <td>0</td>
1055 <td>0</td>
1056 </tr>
1057 <tr>
1058 <td>1</td>
1059 <td>1</td>
1060 <td>1</td>
1061 </tr>
1062 </tbody>
1063</table>
1064</center>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1065<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1066<pre> &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 &amp; %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1067 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1068 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1069</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1070</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1071<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1072<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1073<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1074<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1075<pre> &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1076</pre>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1077<h5>Overview:</h5>
1078<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
1079or of its two operands.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1080<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1081<p>The two arguments to the '<tt>or</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1082 href="#t_integral">integral</a> values. Both arguments must have
1083identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1084<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1085<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1086<p> </p>
1087<center>
1088<table border="1" cellspacing="0" cellpadding="4">
1089 <tbody>
1090 <tr>
1091 <td>In0</td>
1092 <td>In1</td>
1093 <td>Out</td>
1094 </tr>
1095 <tr>
1096 <td>0</td>
1097 <td>0</td>
1098 <td>0</td>
1099 </tr>
1100 <tr>
1101 <td>0</td>
1102 <td>1</td>
1103 <td>1</td>
1104 </tr>
1105 <tr>
1106 <td>1</td>
1107 <td>0</td>
1108 <td>1</td>
1109 </tr>
1110 <tr>
1111 <td>1</td>
1112 <td>1</td>
1113 <td>1</td>
1114 </tr>
1115 </tbody>
1116</table>
1117</center>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1118<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1119<pre> &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1120 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1121 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1122</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1123</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1124<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1125<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
1126Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1127<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1128<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1129<pre> &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1130</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1131<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1132<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
1133or of its two operands. The <tt>xor</tt> is used to implement the
1134"one's complement" operation, which is the "~" operator in C.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1135<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1136<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1137 href="#t_integral">integral</a> values. Both arguments must have
1138identical types.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1139<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1140<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1141<p> </p>
1142<center>
1143<table border="1" cellspacing="0" cellpadding="4">
1144 <tbody>
1145 <tr>
1146 <td>In0</td>
1147 <td>In1</td>
1148 <td>Out</td>
1149 </tr>
1150 <tr>
1151 <td>0</td>
1152 <td>0</td>
1153 <td>0</td>
1154 </tr>
1155 <tr>
1156 <td>0</td>
1157 <td>1</td>
1158 <td>1</td>
1159 </tr>
1160 <tr>
1161 <td>1</td>
1162 <td>0</td>
1163 <td>1</td>
1164 </tr>
1165 <tr>
1166 <td>1</td>
1167 <td>1</td>
1168 <td>0</td>
1169 </tr>
1170 </tbody>
1171</table>
1172</center>
1173<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1174<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1175<pre> &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1176 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1177 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
Chris Lattner27f71f22003-09-03 00:41:47 +0000[diff] [blame]1178 &lt;result&gt; = xor int %V, -1 <i>; yields {int}:result = ~%V</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1179</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1180</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1181<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1182<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
1183Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1184<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1185<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1186<pre> &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1187</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1188<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1189<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
1190the left a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1191<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1192<p>The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1193 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1194type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1195<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1196<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1197<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1198<pre> &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 &lt;&lt; %var</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1199 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1200 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1201</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1202</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1203<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1204<div class="doc_subsubsection"> <a name="i_shr">'<tt>shr</tt>'
1205Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1206<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1207<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1208<pre> &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1209</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1210<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1211<p>The '<tt>shr</tt>' instruction returns the first operand shifted to
1212the right a specified number of bits.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1213<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1214<p>The first argument to the '<tt>shr</tt>' instruction must be an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1215 href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>'
1216type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1217<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1218<p>If the first argument is a <a href="#t_signed">signed</a> type, the
1219most significant bit is duplicated in the newly free'd bit positions.
1220If the first argument is unsigned, zero bits shall fill the empty
1221positions.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1222<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1223<pre> &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 &gt;&gt; %var</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1224 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1225 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame]1226 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1227 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1228</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1229</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1230<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1231<div class="doc_subsection"> <a name="memoryops">Memory Access
1232Operations</a></div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1233<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1234<p>A key design point of an SSA-based representation is how it
1235represents memory. In LLVM, no memory locations are in SSA form, which
1236makes things very simple. This section describes how to read, write,
1237allocate and free memory in LLVM.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1238</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1239<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1240<div class="doc_subsubsection"> <a name="i_malloc">'<tt>malloc</tt>'
1241Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1242<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1243<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1244<pre> &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1245 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1246</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1247<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1248<p>The '<tt>malloc</tt>' instruction allocates memory from the system
1249heap and returns a pointer to it.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1250<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1251<p>The the '<tt>malloc</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1252bytes of memory from the operating system, and returns a pointer of the
1253appropriate type to the program. The second form of the instruction is
1254a shorter version of the first instruction that defaults to allocating
1255one element.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1256<p>'<tt>type</tt>' must be a sized type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1257<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1258<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
1259a pointer is returned.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1260<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1261<pre> %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1262
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1263 %size = <a
1264 href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1265 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1266 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1267</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1268</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1269<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1270<div class="doc_subsubsection"> <a name="i_free">'<tt>free</tt>'
1271Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1272<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1273<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1274<pre> free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1275</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1276<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1277<p>The '<tt>free</tt>' instruction returns memory back to the unused
1278memory heap, to be reallocated in the future.</p>
1279<p> </p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1280<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1281<p>'<tt>value</tt>' shall be a pointer value that points to a value
1282that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
1283instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1284<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1285<p>Access to the memory pointed to by the pointer is not longer defined
1286after this instruction executes.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1287<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1288<pre> %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1289 free [4 x ubyte]* %array
1290</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1291</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1292<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1293<div class="doc_subsubsection"> <a name="i_alloca">'<tt>alloca</tt>'
1294Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1295<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1296<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1297<pre> &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1298 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1299</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1300<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1301<p>The '<tt>alloca</tt>' instruction allocates memory on the current
1302stack frame of the procedure that is live until the current function
1303returns to its caller.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1304<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1305<p>The the '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
1306bytes of memory on the runtime stack, returning a pointer of the
1307appropriate type to the program. The second form of the instruction is
1308a shorter version of the first that defaults to allocating one element.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1309<p>'<tt>type</tt>' may be any sized type.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1310<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1311<p>Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d
1312memory is automatically released when the function returns. The '<tt>alloca</tt>'
1313instruction is commonly used to represent automatic variables that must
1314have an address available. When the function returns (either with the <tt><a
1315 href="#i_ret">ret</a></tt> or <tt><a href="#i_invoke">invoke</a></tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1316instructions), the memory is reclaimed.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1317<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1318<pre> %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1319 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1320</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1321</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1322<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1323<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
1324Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1325<div class="doc_text">
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1326<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1327<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 Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1328<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1329<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1330<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1331<p>The argument to the '<tt>load</tt>' instruction specifies the memory
1332address to load from. The pointer must point to a <a
1333 href="t_firstclass">first class</a> type. If the <tt>load</tt> is
1334marked as <tt>volatile</tt> then the optimizer is not allowed to modify
1335the number or order of execution of this <tt>load</tt> with other
1336volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
1337instructions. </p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1338<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1339<p>The location of memory pointed to is loaded.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1340<h5>Examples:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1341<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1342 <a
1343 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1344 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1345</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1346</div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1347<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1348<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
1349Instruction</a> </div>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1350<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1351<pre> store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattnerf0651072003-09-08 18:27:49 +0000[diff] [blame]1352 volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1353</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1354<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1355<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1356<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1357<p>There are two arguments to the '<tt>store</tt>' instruction: a value
1358to store and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1359operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
1360operand. If the <tt>store</tt> is marked as <tt>volatile</tt> then the
1361optimizer is not allowed to modify the number or order of execution of
1362this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
1363 href="#i_store">store</a></tt> instructions.</p>
1364<h5>Semantics:</h5>
1365<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
1366at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1367<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1368<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1369 <a
1370 href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1371 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1372</pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1373<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1374<div class="doc_subsubsection"> <a name="i_getelementptr">'<tt>getelementptr</tt>'
1375Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1376<div class="doc_text">
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1377<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1378<pre> &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, long &lt;aidx&gt;|, ubyte &lt;sidx&gt;}*<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1379<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1380<p>The '<tt>getelementptr</tt>' instruction is used to get the address
1381of a subelement of an aggregate data structure.</p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1382<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1383<p>This instruction takes a list of <tt>long</tt> values and <tt>ubyte</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1384constants that indicate what form of addressing to perform. The actual
1385types of the arguments provided depend on the type of the first pointer
1386argument. The '<tt>getelementptr</tt>' instruction is used to index
1387down through the type levels of a structure.</p>
1388<p>For example, let's consider a C code fragment and how it gets
1389compiled to LLVM:</p>
1390<pre>struct RT {<br> char A;<br> int B[10][20];<br> char C;<br>};<br>struct ST {<br> int X;<br> double Y;<br> struct RT Z;<br>};<br><br>int *foo(struct ST *s) {<br> return &amp;s[1].Z.B[5][13];<br>}<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1391<p>The LLVM code generated by the GCC frontend is:</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1392<pre>%RT = type { sbyte, [10 x [20 x int]], sbyte }<br>%ST = type { int, double, %RT }<br><br>int* "foo"(%ST* %s) {<br> %reg = getelementptr %ST* %s, long 1, ubyte 2, ubyte 1, long 5, long 13<br> ret int* %reg<br>}<br></pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1393<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1394<p>The index types specified for the '<tt>getelementptr</tt>'
1395instruction depend on the pointer type that is being index into. <a
1396 href="t_pointer">Pointer</a> and <a href="t_array">array</a> types
1397require '<tt>long</tt>' values, and <a href="t_struct">structure</a>
1398types require '<tt>ubyte</tt>' <b>constants</b>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1399<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1400type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int,
1401double, %RT }</tt>' type, a structure. The second index indexes into
1402the third element of the structure, yielding a '<tt>%RT</tt>' = '<tt>{
1403sbyte, [10 x [20 x int]], sbyte }</tt>' type, another structure. The
1404third index indexes into the second element of the structure, yielding
1405a '<tt>[10 x [20 x int]]</tt>' type, an array. The two dimensions of
1406the array are subscripted into, yielding an '<tt>int</tt>' type. The '<tt>getelementptr</tt>'
1407instruction return a pointer to this element, thus yielding a '<tt>int*</tt>'
1408type.</p>
1409<p>Note that it is perfectly legal to index partially through a
1410structure, returning a pointer to an inner element. Because of this,
1411the LLVM code for the given testcase is equivalent to:</p>
1412<pre>int* "foo"(%ST* %s) {<br> %t1 = getelementptr %ST* %s , long 1 <i>; yields %ST*:%t1</i>
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1413 %t2 = getelementptr %ST* %t1, long 0, ubyte 2 <i>; yields %RT*:%t2</i>
1414 %t3 = getelementptr %RT* %t2, long 0, ubyte 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1415 %t4 = getelementptr [10 x [20 x int]]* %t3, long 0, long 5 <i>; yields [20 x int]*:%t4</i>
1416 %t5 = getelementptr [20 x int]* %t4, long 0, long 13 <i>; yields int*:%t5</i>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1417 ret int* %t5
1418}
1419</pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1420<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1421<pre> <i>; yields [12 x ubyte]*:aptr</i>
1422 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, ubyte 1<br></pre>
1423<h5>&nbsp;Note To The Novice:</h5>
1424When using indexing into global arrays with the '<tt>getelementptr</tt>'
1425instruction, you must remember that the&nbsp; </div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1426<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1427<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1428<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1429<p>The instructions in this catagory are the "miscellaneous"
1430instructions, which defy better classification.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1431</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1432<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1433<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
1434Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1435<div class="doc_text">
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1436<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1437<pre> &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1438<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1439<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
1440the SSA graph representing the function.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1441<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1442<p>The type of the incoming values are specified with the first type
1443field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
1444as arguments, with one pair for each predecessor basic block of the
1445current block. Only values of <a href="#t_firstclass">first class</a>
1446type may be used as the value arguments to the PHI node. Only labels
1447may be used as the label arguments.</p>
1448<p>There must be no non-phi instructions between the start of a basic
1449block and the PHI instructions: i.e. PHI instructions must be first in
1450a basic block.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1451<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1452<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
1453value specified by the parameter, depending on which basic block we
1454came from in the last <a href="#terminators">terminator</a> instruction.</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1455<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1456<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 Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1457</div>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1458<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1459<div class="doc_subsubsection"> <a name="i_cast">'<tt>cast .. to</tt>'
1460Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1461<div class="doc_text">
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1462<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1463<pre> &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1464</pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1465<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1466<p>The '<tt>cast</tt>' instruction is used as the primitive means to
1467convert integers to floating point, change data type sizes, and break
1468type safety (by casting pointers).</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1469<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1470<p>The '<tt>cast</tt>' instruction takes a value to cast, which must be
1471a first class value, and a type to cast it to, which must also be a <a
1472 href="#t_firstclass">first class</a> type.</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1473<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1474<p>This instruction follows the C rules for explicit casts when
1475determining how the data being cast must change to fit in its new
1476container.</p>
1477<p>When casting to bool, any value that would be considered true in the
1478context of a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>'
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1479values, all else are '<tt>false</tt>'.</p>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1480<p>When extending an integral value from a type of one signness to
1481another (for example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value
1482is sign-extended if the <b>source</b> value is signed, and
1483zero-extended if the source value is unsigned. <tt>bool</tt> values
1484are always zero extended into either zero or one.</p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1485<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1486<pre> %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1487 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1488</pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1489</div>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1490<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1491<div class="doc_subsubsection"> <a name="i_call">'<tt>call</tt>'
1492Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1493<div class="doc_text">
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1494<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1495<pre> &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)<br></pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1496<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1497<p>The '<tt>call</tt>' instruction represents a simple function call.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1498<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1499<p>This instruction requires several arguments:</p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1500<ol>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1501 <li>
1502 <p>'<tt>ty</tt>': shall be the signature of the pointer to function
1503value being invoked. The argument types must match the types implied
1504by this signature.</p>
1505 </li>
1506 <li>
1507 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a
1508function to be invoked. In most cases, this is a direct function
1509invocation, but indirect <tt>call</tt>s are just as possible,
1510calling an arbitrary pointer to function values.</p>
1511 </li>
1512 <li>
1513 <p>'<tt>function args</tt>': argument list whose types match the
1514function signature argument types. If the function signature
1515indicates the function accepts a variable number of arguments, the
1516extra arguments can be specified.</p>
1517 </li>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1518</ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1519<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1520<p>The '<tt>call</tt>' instruction is used to cause control flow to
1521transfer to a specified function, with its incoming arguments bound to
1522the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
1523instruction in the called function, control flow continues with the
1524instruction after the function call, and the return value of the
1525function is bound to the result argument. This is a simpler case of
1526the <a href="#i_invoke">invoke</a> instruction.</p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1527<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1528<pre> %retval = call int %test(int %argc)<br> call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1529</div>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1530<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1531<div class="doc_subsubsection"> <a name="i_vanext">'<tt>vanext</tt>'
1532Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1533<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1534<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1535<pre> &lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1536<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1537<p>The '<tt>vanext</tt>' instruction is used to access arguments passed
1538through the "variable argument" area of a function call. It is used to
1539implement the <tt>va_arg</tt> macro in C.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1540<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1541<p>This instruction takes a <tt>valist</tt> value and the type of the
1542argument. It returns another <tt>valist</tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1543<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1544<p>The '<tt>vanext</tt>' instruction advances the specified <tt>valist</tt>
1545past an argument of the specified type. In conjunction with the <a
1546 href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement
1547the <tt>va_arg</tt> macro available in C. For more information, see
1548the variable argument handling <a href="#int_varargs">Intrinsic
1549Functions</a>.</p>
1550<p>It is legal for this instruction to be called in a function which
1551does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1552function.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1553<p><tt>vanext</tt> is an LLVM instruction instead of an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1554 href="#intrinsics">intrinsic function</a> because it takes an type as
1555an argument.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1556<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1557<p>See the <a href="#int_varargs">variable argument processing</a>
1558section.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1559</div>
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]1560<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1561<div class="doc_subsubsection"> <a name="i_vaarg">'<tt>vaarg</tt>'
1562Instruction</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1563<div class="doc_text">
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]1564<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1565<pre> &lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;<br></pre>
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]1566<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1567<p>The '<tt>vaarg</tt>' instruction is used to access arguments passed
1568through the "variable argument" area of a function call. It is used to
1569implement the <tt>va_arg</tt> macro in C.</p>
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]1570<h5>Arguments:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1571<p>This instruction takes a <tt>valist</tt> value and the type of the
1572argument. It returns a value of the specified argument type.</p>
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]1573<h5>Semantics:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1574<p>The '<tt>vaarg</tt>' instruction loads an argument of the specified
1575type from the specified <tt>va_list</tt>. In conjunction with the <a
1576 href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to
1577implement the <tt>va_arg</tt> macro available in C. For more
1578information, see the variable argument handling <a href="#int_varargs">Intrinsic
1579Functions</a>.</p>
1580<p>It is legal for this instruction to be called in a function which
1581does not take a variable number of arguments, for example, the <tt>vfprintf</tt>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1582function.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1583<p><tt>vaarg</tt> is an LLVM instruction instead of an <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1584 href="#intrinsics">intrinsic function</a> because it takes an type as
1585an argument.</p>
Chris Lattner8d1a81d2003-10-18 05:51:36 +0000[diff] [blame]1586<h5>Example:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1587<p>See the <a href="#int_varargs">variable argument processing</a>
1588section.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1589</div>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1590<!-- *********************************************************************** -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1591<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
1592<!-- *********************************************************************** -->
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1593<div class="doc_text">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1594<p>LLVM supports the notion of an "intrinsic function". These
1595functions have well known names and semantics, and are required to
1596follow certain restrictions. Overall, these instructions represent an
1597extension mechanism for the LLVM language that does not require
1598changing all of the transformations in LLVM to add to the language (or
1599the bytecode reader/writer, the parser, etc...).</p>
1600<p>Intrinsic function names must all start with an "<tt>llvm.</tt>"
1601prefix, this prefix is reserved in LLVM for intrinsic names, thus
1602functions may not be named this. Intrinsic functions must always be
1603external functions: you cannot define the body of intrinsic functions.
1604Intrinsic functions may only be used in call or invoke instructions: it
1605is illegal to take the address of an intrinsic function. Additionally,
1606because intrinsic functions are part of the LLVM language, it is
1607required that they all be documented here if any are added.</p>
1608<p>Unless an intrinsic function is target-specific, there must be a
1609lowering pass to eliminate the intrinsic or all backends must support
1610the intrinsic function.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1611</div>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1612<!-- ======================================================================= -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1613<div class="doc_subsection"> <a name="int_varargs">Variable Argument
1614Handling Intrinsics</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1615<div class="doc_text">
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1616<p>Variable argument support is defined in LLVM with the <a
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1617 href="#i_vanext"><tt>vanext</tt></a> instruction and these three
1618intrinsic functions. These functions are related to the similarly
1619named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>
1620<p>All of these functions operate on arguments that use a
1621target-specific value type "<tt>va_list</tt>". The LLVM assembly
1622language reference manual does not define what this type is, so all
1623transformations should be prepared to handle intrinsics with any type
1624used.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1625<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1626instruction and the variable argument handling intrinsic functions are
1627used.</p>
1628<pre>int %test(int %X, ...) {<br> ; Initialize variable argument processing<br> %ap = call sbyte*()* %<a
1629 href="#i_va_start">llvm.va_start</a>()<br><br> ; Read a single integer argument<br> %tmp = vaarg sbyte* %ap, int<br><br> ; Advance to the next argument<br> %ap2 = vanext sbyte* %ap, int<br><br> ; Demonstrate usage of llvm.va_copy and llvm.va_end<br> %aq = call sbyte* (sbyte*)* %<a
1630 href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)<br> call void %<a
1631 href="#i_va_end">llvm.va_end</a>(sbyte* %aq)<br><br> ; Stop processing of arguments.<br> call void %<a
1632 href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)<br> ret int %tmp<br>}<br></pre>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1633</div>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1634<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1635<div class="doc_subsubsection"> <a name="i_va_start">'<tt>llvm.va_start</tt>'
1636Intrinsic</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1637<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1638<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1639<pre> call va_list ()* %llvm.va_start()<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1640<h5>Overview:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1641<p>The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
1642for subsequent use by the variable argument intrinsics.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1643<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1644<p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1645macro available in C. In a target-dependent way, it initializes and
1646returns a <tt>va_list</tt> element, so that the next <tt>vaarg</tt>
1647will produce the first variable argument passed to the function. Unlike
1648the C <tt>va_start</tt> macro, this intrinsic does not need to know the
1649last argument of the function, the compiler can figure that out.</p>
1650<p>Note that this intrinsic function is only legal to be called from
1651within the body of a variable argument function.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1652</div>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1653<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1654<div class="doc_subsubsection"> <a name="i_va_end">'<tt>llvm.va_end</tt>'
1655Intrinsic</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1656<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1657<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1658<pre> call void (va_list)* %llvm.va_end(va_list &lt;arglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1659<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1660<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt>
1661which has been initialized previously with <tt><a href="#i_va_start">llvm.va_start</a></tt>
1662or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1663<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1664<p>The argument is a <tt>va_list</tt> to destroy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1665<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1666<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1667macro available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
1668Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
1669 href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly
1670with calls to <tt>llvm.va_end</tt>.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1671</div>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1672<!-- _______________________________________________________________________ -->
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1673<div class="doc_subsubsection"> <a name="i_va_copy">'<tt>llvm.va_copy</tt>'
1674Intrinsic</a> </div>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1675<div class="doc_text">
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1676<h5>Syntax:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1677<pre> call va_list (va_list)* %llvm.va_copy(va_list &lt;destarglist&gt;)<br></pre>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1678<h5>Overview:</h5>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1679<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument
1680position from the source argument list to the destination argument list.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1681<h5>Arguments:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1682<p>The argument is the <tt>va_list</tt> to copy.</p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1683<h5>Semantics:</h5>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1684<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1685macro available in C. In a target-dependent way, it copies the source <tt>va_list</tt>
1686element into the returned list. This intrinsic is necessary because the <tt><a
1687 href="i_va_start">llvm.va_start</a></tt> intrinsic may be arbitrarily
1688complex and require memory allocation, for example.</p>
Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1689</div>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1690<!-- *********************************************************************** -->
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Misha Brukman9d0919f2003-11-08 01:05:38 +0000[diff] [blame]1692<div class="doc_footer">
Chris Lattner261efe92003-11-25 01:02:51 +0000[diff] [blame]1693<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
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