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Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
2<html><head><title>llvm Assembly Language Reference Manual</title></head>
3<body bgcolor=white>
4
5<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
6<tr><td>&nbsp; <font size=+5 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>llvm Assembly Language Reference Manual</b></font></td>
7</tr></table>
8
9<ol>
10 <li><a href="#abstract">Abstract</a>
11 <li><a href="#introduction">Introduction</a>
12 <li><a href="#identifiers">Identifiers</a>
13 <li><a href="#typesystem">Type System</a>
14 <ol>
15 <li><a href="#t_primitive">Primitive Types</a>
16 <ol>
17 <li><a href="#t_classifications">Type Classifications</a>
18 </ol>
19 <li><a href="#t_derived">Derived Types</a>
20 <ol>
21 <li><a href="#t_array" >Array Type</a>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]22 <li><a href="#t_function">Function Type</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]23 <li><a href="#t_pointer">Pointer Type</a>
24 <li><a href="#t_struct" >Structure Type</a>
Chris Lattner690d99b2002-08-29 18:33:48 +0000[diff] [blame]25 <!-- <li><a href="#t_packed" >Packed Type</a> -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]26 </ol>
27 </ol>
28 <li><a href="#highlevel">High Level Structure</a>
29 <ol>
30 <li><a href="#modulestructure">Module Structure</a>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]31 <li><a href="#globalvars">Global Variables</a>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]32 <li><a href="#functionstructure">Function Structure</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]33 </ol>
34 <li><a href="#instref">Instruction Reference</a>
35 <ol>
36 <li><a href="#terminators">Terminator Instructions</a>
37 <ol>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]38 <li><a href="#i_ret" >'<tt>ret</tt>' Instruction</a>
39 <li><a href="#i_br" >'<tt>br</tt>' Instruction</a>
40 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a>
41 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]42 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]43 <li><a href="#binaryops">Binary Operations</a>
44 <ol>
45 <li><a href="#i_add" >'<tt>add</tt>' Instruction</a>
46 <li><a href="#i_sub" >'<tt>sub</tt>' Instruction</a>
47 <li><a href="#i_mul" >'<tt>mul</tt>' Instruction</a>
48 <li><a href="#i_div" >'<tt>div</tt>' Instruction</a>
49 <li><a href="#i_rem" >'<tt>rem</tt>' Instruction</a>
50 <li><a href="#i_setcc">'<tt>set<i>cc</i></tt>' Instructions</a>
51 </ol>
52 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
53 <ol>
54 <li><a href="#i_and">'<tt>and</tt>' Instruction</a>
55 <li><a href="#i_or" >'<tt>or</tt>' Instruction</a>
56 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a>
57 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a>
58 <li><a href="#i_shr">'<tt>shr</tt>' Instruction</a>
59 </ol>
60 <li><a href="#memoryops">Memory Access Operations</a>
61 <ol>
62 <li><a href="#i_malloc" >'<tt>malloc</tt>' Instruction</a>
63 <li><a href="#i_free" >'<tt>free</tt>' Instruction</a>
64 <li><a href="#i_alloca" >'<tt>alloca</tt>' Instruction</a>
65 <li><a href="#i_load" >'<tt>load</tt>' Instruction</a>
66 <li><a href="#i_store" >'<tt>store</tt>' Instruction</a>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]67 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]68 </ol>
69 <li><a href="#otherops">Other Operations</a>
70 <ol>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]71 <li><a href="#i_phi" >'<tt>phi</tt>' Instruction</a>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]72 <li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]73 <li><a href="#i_call" >'<tt>call</tt>' Instruction</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]74 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]75 </ol>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]76<!--
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]77 <li><a href="#related">Related Work</a>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]78-->
Chris Lattnerd816bcf2002-08-30 21:50:21 +0000[diff] [blame]79
80 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a> and <A href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></b><p>
81
82
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]83</ol>
84
85
86<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]87<p><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
88<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]89<a name="abstract">Abstract
90</b></font></td></tr></table><ul>
91<!-- *********************************************************************** -->
92
93<blockquote>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]94 This document is a reference manual for the LLVM assembly language. LLVM is
95 an SSA based representation that provides type safety, low level operations,
96 flexibility, and the capability of representing 'all' high level languages
97 cleanly. It is the common code representation used throughout all phases of
98 the LLVM compilation strategy.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]99</blockquote>
100
101
102
103
104<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]105</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
106<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]107<a name="introduction">Introduction
108</b></font></td></tr></table><ul>
109<!-- *********************************************************************** -->
110
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]111The LLVM code representation is designed to be used in three different forms: as
112an in-memory compiler IR, as an on-disk bytecode representation, suitable for
113fast loading by a dynamic compiler, and as a human readable assembly language
114representation. This allows LLVM to provide a powerful intermediate
115representation for efficient compiler transformations and analysis, while
116providing a natural means to debug and visualize the transformations. The three
117different forms of LLVM are all equivalent. This document describes the human
118readable representation and notation.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]119
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]120The LLVM representation aims to be a light weight and low level while being
Chris Lattnerb7c6c2a2002-06-25 20:20:08 +0000[diff] [blame]121expressive, typed, and extensible at the same time. It aims to be a "universal
122IR" of sorts, by being at a low enough level that high level ideas may be
123cleanly mapped to it (similar to how microprocessors are "universal IR's",
124allowing many source languages to be mapped to them). By providing type
125information, LLVM can be used as the target of optimizations: for example,
126through pointer analysis, it can be proven that a C automatic variable is never
127accessed outside of the current function... allowing it to be promoted to a
128simple SSA value instead of a memory location.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]129
130<!-- _______________________________________________________________________ -->
131</ul><a name="wellformed"><h4><hr size=0>Well Formedness</h4><ul>
132
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]133It is important to note that this document describes 'well formed' llvm assembly
134language. There is a difference between what the parser accepts and what is
135considered 'well formed'. For example, the following instruction is
136syntactically okay, but not well formed:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]137
138<pre>
139 %x = <a href="#i_add">add</a> int 1, %x
140</pre>
141
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]142...because the definition of %x does not dominate all of its uses. The LLVM
143infrastructure provides a verification pass that may be used to verify that an
144LLVM module is well formed. This pass is automatically run by the parser after
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]145parsing input assembly, and by the optimizer before it outputs bytecode. The
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]146violations pointed out by the verifier pass indicate bugs in transformation
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]147passes or input to the parser.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]148
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]149<!-- Describe the typesetting conventions here. -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]150
151
152<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]153</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
154<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]155<a name="identifiers">Identifiers
156</b></font></td></tr></table><ul>
157<!-- *********************************************************************** -->
158
159LLVM uses three different forms of identifiers, for different purposes:<p>
160
161<ol>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]162<li>Numeric constants are represented as you would expect: 12, -3 123.421, etc. Floating point constants have an optional hexidecimal notation.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]163<li>Named values are represented as a string of characters with a '%' prefix. For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
164<li>Unnamed values are represented as an unsigned numeric value with a '%' prefix. For example, %12, %2, %44.
165</ol><p>
166
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]167LLVM requires the values start with a '%' sign for two reasons: Compilers don't
168need to worry about name clashes with reserved words, and the set of reserved
169words may be expanded in the future without penalty. Additionally, unnamed
170identifiers allow a compiler to quickly come up with a temporary variable
171without having to avoid symbol table conflicts.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]172
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]173Reserved words in LLVM are very similar to reserved words in other languages.
174There are keywords for different opcodes ('<tt><a href="#i_add">add</a></tt>',
175'<tt><a href="#i_cast">cast</a></tt>', '<tt><a href="#i_ret">ret</a></tt>',
176etc...), for primitive type names ('<tt><a href="#t_void">void</a></tt>',
177'<tt><a href="#t_uint">uint</a></tt>', etc...), and others. These reserved
178words cannot conflict with variable names, because none of them start with a '%'
179character.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]180
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]181Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>'
182by 8:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]183
184The easy way:
185<pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]186 %result = <a href="#i_mul">mul</a> uint %X, 8
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]187</pre>
188
189After strength reduction:
190<pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]191 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]192</pre>
193
194And the hard way:
195<pre>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]196 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
197 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]198 %result = <a href="#i_add">add</a> uint %1, %1
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]199</pre>
200
201This last way of multiplying <tt>%X</tt> by 8 illustrates several important lexical features of LLVM:<p>
202
203<ol>
204<li>Comments are delimited with a '<tt>;</tt>' and go until the end of line.
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]205<li>Unnamed temporaries are created when the result of a computation is not
206 assigned to a named value.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]207<li>Unnamed temporaries are numbered sequentially
208</ol><p>
209
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]210...and it also show a convention that we follow in this document. When
211demonstrating instructions, we will follow an instruction with a comment that
212defines the type and name of value produced. Comments are shown in italic
213text.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]214
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]215The one unintuitive notation for constants is the optional hexidecimal form of
216floating point constants. For example, the form '<tt>double
2170x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
2184.5e+15</tt>' which is also supported by the parser. The only time hexadecimal
219floating point constants are useful (and the only time that they are generated
220by the disassembler) is when an FP constant has to be emitted that is not
221representable as a decimal floating point number exactly. For example, NaN's,
222infinities, and other special cases are represented in their IEEE hexadecimal
223format so that assembly and disassembly do not cause any bits to change in the
224constants.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]225
226
227<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]228</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
229<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]230<a name="typesystem">Type System
231</b></font></td></tr></table><ul>
232<!-- *********************************************************************** -->
233
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]234The LLVM type system is one of the most important features of the intermediate
Chris Lattnerb7c6c2a2002-06-25 20:20:08 +0000[diff] [blame]235representation. Being typed enables a number of optimizations to be performed
236on the IR directly, without having to do extra analyses on the side before the
237transformation. A strong type system makes it easier to read the generated code
238and enables novel analyses and transformations that are not feasible to perform
239on normal three address code representations.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]240
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]241<!-- The written form for the type system was heavily influenced by the
242syntactic problems with types in the C language<sup><a
243href="#rw_stroustrup">1</a></sup>.<p> -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]244
245
246
247<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]248</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
249<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]250<a name="t_primitive">Primitive Types
251</b></font></td></tr></table><ul>
252
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]253The primitive types are the fundemental building blocks of the LLVM system. The
254current set of primitive types are as follows:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]255
256<table border=0 align=center><tr><td>
257
258<table border=1 cellspacing=0 cellpadding=4 align=center>
259<tr><td><tt>void</tt></td> <td>No value</td></tr>
260<tr><td><tt>ubyte</tt></td> <td>Unsigned 8 bit value</td></tr>
261<tr><td><tt>ushort</tt></td><td>Unsigned 16 bit value</td></tr>
262<tr><td><tt>uint</tt></td> <td>Unsigned 32 bit value</td></tr>
263<tr><td><tt>ulong</tt></td> <td>Unsigned 64 bit value</td></tr>
264<tr><td><tt>float</tt></td> <td>32 bit floating point value</td></tr>
265<tr><td><tt>label</tt></td> <td>Branch destination</td></tr>
266</table>
267
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]268</td><td valign=top>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]269
270<table border=1 cellspacing=0 cellpadding=4 align=center>
271<tr><td><tt>bool</tt></td> <td>True or False value</td></tr>
272<tr><td><tt>sbyte</tt></td> <td>Signed 8 bit value</td></tr>
273<tr><td><tt>short</tt></td> <td>Signed 16 bit value</td></tr>
274<tr><td><tt>int</tt></td> <td>Signed 32 bit value</td></tr>
275<tr><td><tt>long</tt></td> <td>Signed 64 bit value</td></tr>
276<tr><td><tt>double</tt></td><td>64 bit floating point value</td></tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]277</table>
278
279</td></tr></table><p>
280
281
282
283<!-- _______________________________________________________________________ -->
284</ul><a name="t_classifications"><h4><hr size=0>Type Classifications</h4><ul>
285
286These different primitive types fall into a few useful classifications:<p>
287
288<table border=1 cellspacing=0 cellpadding=4 align=center>
289<tr><td><a name="t_signed">signed</td> <td><tt>sbyte, short, int, long, float, double</tt></td></tr>
290<tr><td><a name="t_unsigned">unsigned</td><td><tt>ubyte, ushort, uint, ulong</tt></td></tr>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]291<tr><td><a name="t_integral">integer</td><td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td></tr>
292<tr><td><a name="t_integral">integral</td><td><tt>bool, ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td></tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]293<tr><td><a name="t_floating">floating point</td><td><tt>float, double</tt></td></tr>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]294<tr><td><a name="t_firstclass">first class</td><td><tt>bool, ubyte, sbyte, ushort, short,<br> uint, int, ulong, long, float, double, <a href="#t_pointer">pointer</a></tt></td></tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]295</table><p>
296
297
298
299
300
301<!-- ======================================================================= -->
302</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
303<a name="t_derived">Derived Types
304</b></font></td></tr></table><ul>
305
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]306The real power in LLVM comes from the derived types in the system. This is what
307allows a programmer to represent arrays, functions, pointers, and other useful
308types. Note that these derived types may be recursive: For example, it is
309possible to have a two dimensional array.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]310
311
312
313<!-- _______________________________________________________________________ -->
314</ul><a name="t_array"><h4><hr size=0>Array Type</h4><ul>
315
316<h5>Overview:</h5>
317
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]318The array type is a very simple derived type that arranges elements sequentially
319in memory. The array type requires a size (number of elements) and an
320underlying data type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]321
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]322<h5>Syntax:</h5>
323<pre>
324 [&lt;# elements&gt; x &lt;elementtype&gt;]
325</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]326
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]327The number of elements is a constant integer value, elementtype may be any type
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]328with a size.<p>
329
330<h5>Examples:</h5>
331<ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]332 <tt>[40 x int ]</tt>: Array of 40 integer values.<br>
333 <tt>[41 x int ]</tt>: Array of 41 integer values.<br>
334 <tt>[40 x uint]</tt>: Array of 40 unsigned integer values.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]335</ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]336
337Here are some examples of multidimensional arrays:<p>
338<ul>
339<table border=0 cellpadding=0 cellspacing=0>
340<tr><td><tt>[3 x [4 x int]]</tt></td><td>: 3x4 array integer values.</td></tr>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]341<tr><td><tt>[12 x [10 x float]]</tt></td><td>: 2x10 array of single precision floating point values.</td></tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]342<tr><td><tt>[2 x [3 x [4 x uint]]]</tt></td><td>: 2x3x4 array of unsigned integer values.</td></tr>
343</table>
344</ul>
345
346
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]347<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]348</ul><a name="t_function"><h4><hr size=0>Function Type</h4><ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]349
350<h5>Overview:</h5>
351
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]352The function type can be thought of as a function signature. It consists of a
353return type and a list of formal parameter types. Function types are usually
354used when to build virtual function tables (which are structures of pointers to
355functions), for indirect function calls, and when defining a function.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]356
357<h5>Syntax:</h5>
358<pre>
359 &lt;returntype&gt; (&lt;parameter list&gt;)
360</pre>
361
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]362Where '<tt>&lt;parameter list&gt;</tt>' is a comma seperated list of type
363specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
364which indicates that the function takes a variable number of arguments. Note
365that there currently is no way to define a function in LLVM that takes a
366variable number of arguments, but it is possible to <b>call</b> a function that
367is vararg.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]368
369<h5>Examples:</h5>
370<ul>
371<table border=0 cellpadding=0 cellspacing=0>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]372
373<tr><td><tt>int (int)</tt></td><td>: function taking an <tt>int</tt>, returning
374an <tt>int</tt></td></tr>
375
376<tr><td><tt>float (int, int *) *</tt></td><td>: <a href="#t_pointer">Pointer</a>
377to a function that takes an <tt>int</tt> and a <a href="#t_pointer">pointer</a>
378to <tt>int</tt>, returning <tt>float</tt>.</td></tr>
379
380<tr><td><tt>int (sbyte *, ...)</tt></td><td>: A vararg function that takes at
381least one <a href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C),
382which returns an integer. This is the signature for <tt>printf</tt> in
383LLVM.</td></tr>
384
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]385</table>
386</ul>
387
388
389
390<!-- _______________________________________________________________________ -->
391</ul><a name="t_struct"><h4><hr size=0>Structure Type</h4><ul>
392
393<h5>Overview:</h5>
394
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]395The structure type is used to represent a collection of data members together in
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]396memory. The packing of the field types is defined to match the ABI of the
397underlying processor. The elements of a structure may be any type that has a
398size.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]399
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]400Structures are accessed using '<tt><a href="#i_load">load</a></tt> and '<tt><a
401href="#i_store">store</a></tt>' by getting a pointer to a field with the '<tt><a
402href="#i_getelementptr">getelementptr</a></tt>' instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]403
404<h5>Syntax:</h5>
405<pre>
406 { &lt;type list&gt; }
407</pre>
408
409
410<h5>Examples:</h5>
411<table border=0 cellpadding=0 cellspacing=0>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]412
413<tr><td><tt>{ int, int, int }</tt></td><td>: a triple of three <tt>int</tt>
414values</td></tr>
415
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]416<tr><td><tt>{ float, int (int) * }</tt></td><td>: A pair, where the first
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]417element is a <tt>float</tt> and the second element is a <a
418href="#t_pointer">pointer</a> to a <a href="t_function">function</a> that takes
419an <tt>int</tt>, returning an <tt>int</tt>.</td></tr>
420
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]421</table>
422
423
424<!-- _______________________________________________________________________ -->
425</ul><a name="t_pointer"><h4><hr size=0>Pointer Type</h4><ul>
426
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]427<h5>Overview:</h5>
428
429As in many languages, the pointer type represents a pointer or reference to
430another object, which must live in memory.<p>
431
432<h5>Syntax:</h5>
433<pre>
434 &lt;type&gt; *
435</pre>
436
437<h5>Examples:</h5>
438
439<table border=0 cellpadding=0 cellspacing=0>
440
441<tr><td><tt>[4x int]*</tt></td><td>: <a href="#t_pointer">pointer</a> to <a
442href="#t_array">array</a> of four <tt>int</tt> values</td></tr>
443
444<tr><td><tt>int (int *) *</tt></td><td>: A <a href="#t_pointer">pointer</a> to a
445<a href="t_function">function</a> that takes an <tt>int</tt>, returning an
446<tt>int</tt>.</td></tr>
447
448</table>
449<p>
450
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]451
452<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]453<!--
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]454</ul><a name="t_packed"><h4><hr size=0>Packed Type</h4><ul>
455
456Mention/decide that packed types work with saturation or not. Maybe have a packed+saturated type in addition to just a packed type.<p>
457
458Packed types should be 'nonsaturated' because standard data types are not saturated. Maybe have a saturated packed type?<p>
459
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]460-->
461
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]462
463<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]464</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
465<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]466<a name="highlevel">High Level Structure
467</b></font></td></tr></table><ul>
468<!-- *********************************************************************** -->
469
470
471<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]472</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
473<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]474<a name="modulestructure">Module Structure
475</b></font></td></tr></table><ul>
476
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]477LLVM programs are composed of "Module"s, each of which is a translation unit of
478the input programs. Each module consists of functions, global variables, and
479symbol table entries. Modules may be combined together with the LLVM linker,
480which merges function (and global variable) definitions, resolves forward
481declarations, and merges symbol table entries. Here is an example of the "hello world" module:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]482
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]483<pre>
484<i>; Declare the string constant as a global constant...</i>
485<a href="#identifiers">%.LC0</a> = <a href="#linkage_decl">internal</a> <a href="#globalvars">constant</a> <a href="#t_array">[13 x sbyte]</a> c"hello world\0A\00" <i>; [13 x sbyte]*</i>
486
487<i>; Forward declaration of puts</i>
488<a href="#functionstructure">declare</a> int "puts"(sbyte*) <i>; int(sbyte*)* </i>
489
490<i>; Definition of main function</i>
491int "main"() { <i>; int()* </i>
492 <i>; Convert [13x sbyte]* to sbyte *...</i>
493 %cast210 = <a href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, uint 0, uint 0 <i>; sbyte*</i>
494
495 <i>; Call puts function to write out the string to stdout...</i>
496 <a href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
497 <a href="#i_ret">ret</a> int 0
498}
499</pre>
500
501This example is made up of a <a href="#globalvars">global variable</a> named
502"<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>" function, and a
503<a href="#functionstructure">function definition</a> for "<tt>main</tt>".<p>
504
505<a name="linkage_decl">
506In general, a module is made up of a list of global values, where both functions
507and global variables are global values. Global values are represented by a
508pointer to a memory location (in this case, a pointer to an array of char, and a
509pointer to a function), and can be either "internal" or externally accessible
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]510(which corresponds to the static keyword in C, when used at global scope).<p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]511
512For example, since the "<tt>.LC0</tt>" variable is defined to be internal, if
513another module defined a "<tt>.LC0</tt>" variable and was linked with this one,
514one of the two would be renamed, preventing a collision. Since "<tt>main</tt>"
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]515and "<tt>puts</tt>" are external (i.e., lacking "<tt>internal</tt>"
516declarations), they are accessible outside of the current module. It is illegal
517for a function declaration to be "<tt>internal</tt>".<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]518
519
520<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]521</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
522<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
523<a name="globalvars">Global Variables
524</b></font></td></tr></table><ul>
525
526Global variables define regions of memory allocated at compilation time instead
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]527of run-time. Global variables may optionally be initialized. A variable may
528be defined as a global "constant", which indicates that the contents of the
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]529variable will never be modified (opening options for optimization). Constants
530must always have an initial value.<p>
531
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]532As SSA values, global variables define pointer values that are in scope
533(i.e. they dominate) for all basic blocks in the program. Global variables
534always define a pointer to their "content" type because they describe a region
535of memory, and all memory objects in LLVM are accessed through pointers.<p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]536
537
538
539<!-- ======================================================================= -->
540</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
541<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]542<a name="functionstructure">Function Structure
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]543</b></font></td></tr></table><ul>
544
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]545LLVM functions definitions are composed of a (possibly empty) argument list, an
546opening curly brace, a list of basic blocks, and a closing curly brace. LLVM
547function declarations are defined with the "<tt>declare</tt>" keyword, a
548function name and a function signature.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]549
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]550A function definition contains a list of basic blocks, forming the CFG for the
551function. Each basic block may optionally start with a label (giving the basic
552block a symbol table entry), contains a list of instructions, and ends with a <a
553href="#terminators">terminator</a> instruction (such as a branch or function
554return).<p>
555
556The first basic block in program is special in two ways: it is immediately
557executed on entrance to the function, and it is not allowed to have predecessor
558basic blocks (i.e. there can not be any branches to the entry block of a
559function).<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]560
561
562<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]563</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
564<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]565<a name="instref">Instruction Reference
566</b></font></td></tr></table><ul>
567<!-- *********************************************************************** -->
568
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]569The LLVM instruction set consists of several different classifications of
Chris Lattnere489aa52002-08-14 17:55:59 +0000[diff] [blame]570instructions: <a href="#terminators">terminator instructions</a>, <a
571href="#binaryops">binary instructions</a>, <a href="#memoryops">memory
572instructions</a>, and <a href="#otherops">other instructions</a>.<p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]573
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]574
575<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]576</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
577<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]578<a name="terminators">Terminator Instructions
579</b></font></td></tr></table><ul>
580
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]581As mentioned <a href="#functionstructure">previously</a>, every basic block in a
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]582program ends with a "Terminator" instruction, which indicates which block should
583be executed after the current block is finished. These terminator instructions
584typically yield a '<tt>void</tt>' value: they produce control flow, not values
585(the one exception being the '<a href="#i_invoke"><tt>invoke</tt></a>'
586instruction).<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]587
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]588There are four different terminator instructions: the '<a
589href="#i_ret"><tt>ret</tt></a>' instruction, the '<a
590href="#i_br"><tt>br</tt></a>' instruction, the '<a
591href="#i_switch"><tt>switch</tt></a>' instruction, and the '<a
592href="#i_invoke"><tt>invoke</tt></a>' instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]593
594
595<!-- _______________________________________________________________________ -->
596</ul><a name="i_ret"><h4><hr size=0>'<tt>ret</tt>' Instruction</h4><ul>
597
598<h5>Syntax:</h5>
599<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]600 ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
601 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]602</pre>
603
604<h5>Overview:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]605
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]606The '<tt>ret</tt>' instruction is used to return control flow (and a value) from
607a function, back to the caller.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]608
609There are two forms of the '<tt>ret</tt>' instructruction: one that returns a
610value and then causes control flow, and one that just causes control flow to
611occur.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]612
613<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]614
615The '<tt>ret</tt>' instruction may return any '<a href="#t_firstclass">first
616class</a>' type. Notice that a function is not <a href="#wellformed">well
617formed</a> if there exists a '<tt>ret</tt>' instruction inside of the function
618that returns a value that does not match the return type of the function.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]619
620<h5>Semantics:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]621
622When the '<tt>ret</tt>' instruction is executed, control flow returns back to
623the calling function's context. If the instruction returns a value, that value
Misha Brukmana3bbcb52002-10-29 23:06:16 +0000[diff] [blame]624shall be propagated into the calling function's data space.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]625
626<h5>Example:</h5>
627<pre>
628 ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]629 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]630</pre>
631
632
633<!-- _______________________________________________________________________ -->
634</ul><a name="i_br"><h4><hr size=0>'<tt>br</tt>' Instruction</h4><ul>
635
636<h5>Syntax:</h5>
637<pre>
638 br bool &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;
639 br label &lt;dest&gt; <i>; Unconditional branch</i>
640</pre>
641
642<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]643
644The '<tt>br</tt>' instruction is used to cause control flow to transfer to a
645different basic block in the current function. There are two forms of this
646instruction, corresponding to a conditional branch and an unconditional
647branch.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]648
649<h5>Arguments:</h5>
650
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]651The conditional branch form of the '<tt>br</tt>' instruction takes a single
652'<tt>bool</tt>' value and two '<tt>label</tt>' values. The unconditional form
653of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>' value as a
654target.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]655
656<h5>Semantics:</h5>
657
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]658Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
659argument is evaluated. If the value is <tt>true</tt>, control flows to the
660'<tt>iftrue</tt>' '<tt>label</tt>' argument. If "cond" is <tt>false</tt>,
661control flows to the '<tt>iffalse</tt>' '<tt>label</tt>' argument.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]662
663<h5>Example:</h5>
664<pre>
665Test:
666 %cond = <a href="#i_setcc">seteq</a> int %a, %b
667 br bool %cond, label %IfEqual, label %IfUnequal
668IfEqual:
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]669 <a href="#i_ret">ret</a> int 1
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]670IfUnequal:
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]671 <a href="#i_ret">ret</a> int 0
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]672</pre>
673
674
675<!-- _______________________________________________________________________ -->
676</ul><a name="i_switch"><h4><hr size=0>'<tt>switch</tt>' Instruction</h4><ul>
677
678<h5>Syntax:</h5>
679<pre>
680 <i>; Definitions for lookup indirect branch</i>
681 %switchtype = type [&lt;anysize&gt; x { uint, label }]
682
683 <i>; Lookup indirect branch</i>
684 switch uint &lt;value&gt;, label &lt;defaultdest&gt;, %switchtype &lt;switchtable&gt;
Chris Lattnera0ff4aa2002-11-05 00:21:03 +0000[diff] [blame^]685<!--
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]686 <i>; Indexed indirect branch</i>
687 switch uint &lt;idxvalue&gt;, label &lt;defaultdest&gt;, [&lt;anysize&gt; x label] &lt;desttable&gt;
Chris Lattnera0ff4aa2002-11-05 00:21:03 +0000[diff] [blame^]688-->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]689</pre>
690
691<h5>Overview:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]692
Chris Lattnera0ff4aa2002-11-05 00:21:03 +0000[diff] [blame^]693<b>NOTE:</b> The switch instruction may go away in the future. It is not very
694well supported in LLVM anyway, so don't go to great lengths to support it. Talk
695to <a href="mailto:sabre@nondot.org">Chris</a> for more info if this concerns
696you.<p>
697
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]698The '<tt>switch</tt>' instruction is used to transfer control flow to one of
699several different places. It is a generalization of the '<tt>br</tt>'
700instruction, allowing a branch to occur to one of many possible destinations.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]701
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]702The '<tt>switch</tt>' statement supports two different styles of indirect
703branching: lookup branching and indexed branching. Lookup branching is
704generally useful if the values to switch on are spread far appart, where index
705branching is useful if the values to switch on are generally dense.<p>
706
707The two different forms of the '<tt>switch</tt>' statement are simple hints to
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]708the underlying implementation. For example, the compiler may choose to
709implement a small indirect branch table as a series of predicated comparisons:
710if it is faster for the target architecture.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]711
712<h5>Arguments:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]713
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]714The lookup form of the '<tt>switch</tt>' instruction uses three parameters: a
715'<tt>uint</tt>' comparison value '<tt>value</tt>', a default '<tt>label</tt>'
716destination, and an array of pairs of comparison value constants and
717'<tt>label</tt>'s. The sized array must be a constant value.<p>
718
719The indexed form of the '<tt>switch</tt>' instruction uses three parameters: an
720'<tt>uint</tt>' index value, a default '<tt>label</tt>' and a sized array of
721'<tt>label</tt>'s. The '<tt>dests</tt>' array must be a constant array.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]722
723<h5>Semantics:</h5>
724
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]725The lookup style switch statement specifies a table of values and destinations.
726When the '<tt>switch</tt>' instruction is executed, this table is searched for
727the given value. If the value is found, the corresponding destination is
728branched to. <p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]729
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]730The index branch form simply looks up a label element directly in a table and
731branches to it.<p>
732
733In either case, the compiler knows the static size of the array, because it is
734provided as part of the constant values type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]735
736<h5>Example:</h5>
737<pre>
738 <i>; Emulate a conditional br instruction</i>
739 %Val = <a href="#i_cast">cast</a> bool %value to uint
740 switch uint %Val, label %truedest, [1 x label] [label %falsedest ]
741
742 <i>; Emulate an unconditional br instruction</i>
743 switch uint 0, label %dest, [ 0 x label] [ ]
744
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]745 <i>; Implement a jump table:</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]746 switch uint %val, label %otherwise, [3 x label] [ label %onzero,
747 label %onone,
748 label %ontwo ]
749
750</pre>
751
752
753
754<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]755</ul><a name="i_invoke"><h4><hr size=0>'<tt>invoke</tt>' Instruction</h4><ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]756
757<h5>Syntax:</h5>
758<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]759 &lt;result&gt; = invoke &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
760 to label &lt;normal label&gt; except label &lt;exception label&gt;
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]761</pre>
762
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]763<h5>Overview:</h5>
764
765The '<tt>invoke</tt>' instruction is used to cause control flow to transfer to a
766specified function, with the possibility of control flow transfer to either the
767'<tt>normal label</tt>' label or the '<tt>exception label</tt>'. The '<tt><a
768href="#i_call">call</a></tt>' instruction is closely related, but guarantees
769that control flow either never returns from the called function, or that it
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]770returns to the instruction following the '<tt><a href="#i_call">call</a></tt>'
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]771instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]772
773<h5>Arguments:</h5>
774
775This instruction requires several arguments:<p>
776<ol>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]777
778<li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]779function value being invoked. In most cases, this is a direct function
Misha Brukmane6fe6712002-09-18 02:35:14 +0000[diff] [blame]780invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]781an arbitrary pointer to function value.<p>
782
783<li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
784function to be invoked.
785
786<li>'<tt>function args</tt>': argument list whose types match the function
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]787signature argument types. If the function signature indicates the function
788accepts a variable number of arguments, the extra arguments can be specified.
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]789
790<li>'<tt>normal label</tt>': the label reached when the called function executes
791a '<tt><a href="#i_ret">ret</a></tt>' instruction.
792
793<li>'<tt>exception label</tt>': the label reached when an exception is thrown.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]794</ol>
795
796<h5>Semantics:</h5>
797
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]798This instruction is designed to operate as a standard '<tt><a
799href="#i_call">call</a></tt>' instruction in most regards. The primary
800difference is that it associates a label with the function invocation that may
801be accessed via the runtime library provided by the execution environment. This
802instruction is used in languages with destructors to ensure that proper cleanup
803is performed in the case of either a <tt>longjmp</tt> or a thrown exception.
804Additionally, this is important for implementation of '<tt>catch</tt>' clauses
805in high-level languages that support them.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]806
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]807<!-- For a more comprehensive explanation of how this instruction is used, look in the llvm/docs/2001-05-18-ExceptionHandling.txt document.<p> -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]808
809<h5>Example:</h5>
810<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]811 %retval = invoke int %Test(int 15)
812 to label %Continue except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]813</pre>
814
815
816
817<!-- ======================================================================= -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]818</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
819<a name="binaryops">Binary Operations
820</b></font></td></tr></table><ul>
821
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]822Binary operators are used to do most of the computation in a program. They
823require two operands, execute an operation on them, and produce a single value.
824The result value of a binary operator is not neccesarily the same type as its
825operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]826
827There are several different binary operators:<p>
828
829
830<!-- _______________________________________________________________________ -->
831</ul><a name="i_add"><h4><hr size=0>'<tt>add</tt>' Instruction</h4><ul>
832
833<h5>Syntax:</h5>
834<pre>
835 &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
836</pre>
837
838<h5>Overview:</h5>
839The '<tt>add</tt>' instruction returns the sum of its two operands.<p>
840
841<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]842The two arguments to the '<tt>add</tt>' instruction must be either <a href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]843
844<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]845
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]846The value produced is the integer or floating point sum of the two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]847
848<h5>Example:</h5>
849<pre>
850 &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
851</pre>
852
853
854<!-- _______________________________________________________________________ -->
855</ul><a name="i_sub"><h4><hr size=0>'<tt>sub</tt>' Instruction</h4><ul>
856
857<h5>Syntax:</h5>
858<pre>
859 &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
860</pre>
861
862<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]863
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]864The '<tt>sub</tt>' instruction returns the difference of its two operands.<p>
865
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]866Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
867instruction present in most other intermediate representations.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]868
869<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]870
871The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]872href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]873values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]874
875<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]876
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]877The value produced is the integer or floating point difference of the two
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]878operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]879
880<h5>Example:</h5>
881<pre>
882 &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
883 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
884</pre>
885
886<!-- _______________________________________________________________________ -->
887</ul><a name="i_mul"><h4><hr size=0>'<tt>mul</tt>' Instruction</h4><ul>
888
889<h5>Syntax:</h5>
890<pre>
891 &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
892</pre>
893
894<h5>Overview:</h5>
895The '<tt>mul</tt>' instruction returns the product of its two operands.<p>
896
897<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]898The two arguments to the '<tt>mul</tt>' instruction must be either <a href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]899
900<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]901
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]902The value produced is the integer or floating point product of the two
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]903operands.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]904
905There is no signed vs unsigned multiplication. The appropriate action is taken
906based on the type of the operand. <p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]907
908
909<h5>Example:</h5>
910<pre>
911 &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
912</pre>
913
914
915<!-- _______________________________________________________________________ -->
916</ul><a name="i_div"><h4><hr size=0>'<tt>div</tt>' Instruction</h4><ul>
917
918<h5>Syntax:</h5>
919<pre>
920 &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
921</pre>
922
923<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]924
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]925The '<tt>div</tt>' instruction returns the quotient of its two operands.<p>
926
927<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]928
929The two arguments to the '<tt>div</tt>' instruction must be either <a
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]930href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]931values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]932
933<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]934
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]935The value produced is the integer or floating point quotient of the two
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]936operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]937
938<h5>Example:</h5>
939<pre>
940 &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
941</pre>
942
943
944<!-- _______________________________________________________________________ -->
945</ul><a name="i_rem"><h4><hr size=0>'<tt>rem</tt>' Instruction</h4><ul>
946
947<h5>Syntax:</h5>
948<pre>
949 &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
950</pre>
951
952<h5>Overview:</h5>
953The '<tt>rem</tt>' instruction returns the remainder from the division of its two operands.<p>
954
955<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]956The two arguments to the '<tt>rem</tt>' instruction must be either <a href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]957
958<h5>Semantics:</h5>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]959
960This returns the <i>remainder</i> of a division (where the result has the same
961sign as the divisor), not the <i>modulus</i> (where the result has the same sign
962as the dividend) of a value. For more information about the difference, see: <a
963href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The Math
964Forum</a>.<p>
965
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]966<h5>Example:</h5>
967<pre>
968 &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
969</pre>
970
971
972<!-- _______________________________________________________________________ -->
973</ul><a name="i_setcc"><h4><hr size=0>'<tt>set<i>cc</i></tt>' Instructions</h4><ul>
974
975<h5>Syntax:</h5>
976<pre>
977 &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
978 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
979 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
980 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
981 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
982 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
983</pre>
984
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]985<h5>Overview:</h5> The '<tt>set<i>cc</i></tt>' family of instructions returns a
986boolean value based on a comparison of their two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]987
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]988<h5>Arguments:</h5> The two arguments to the '<tt>set<i>cc</i></tt>'
989instructions must be of <a href="#t_firstclass">first class</a> or <a
990href="#t_pointer">pointer</a> type (it is not possible to compare
991'<tt>label</tt>'s, '<tt>array</tt>'s, '<tt>structure</tt>' or '<tt>void</tt>'
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]992values, etc...). Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]993
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]994The '<tt>setlt</tt>', '<tt>setgt</tt>', '<tt>setle</tt>', and '<tt>setge</tt>'
995instructions do not operate on '<tt>bool</tt>' typed arguments.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]996
997<h5>Semantics:</h5>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]998
999The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
1000both operands are equal.<br>
1001
1002The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
1003both operands are unequal.<br>
1004
1005The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
1006the first operand is less than the second operand.<br>
1007
1008The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
1009the first operand is greater than the second operand.<br>
1010
1011The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
1012the first operand is less than or equal to the second operand.<br>
1013
1014The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
1015the first operand is greater than or equal to the second operand.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1016
1017<h5>Example:</h5>
1018<pre>
1019 &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
1020 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1021 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1022 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1023 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1024 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1025</pre>
1026
1027
1028
1029<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1030</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1031<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1032<a name="bitwiseops">Bitwise Binary Operations
1033</b></font></td></tr></table><ul>
1034
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1035Bitwise binary operators are used to do various forms of bit-twiddling in a
1036program. They are generally very efficient instructions, and can commonly be
1037strength reduced from other instructions. They require two operands, execute an
1038operation on them, and produce a single value. The resulting value of the
1039bitwise binary operators is always the same type as its first operand.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1040
1041<!-- _______________________________________________________________________ -->
1042</ul><a name="i_and"><h4><hr size=0>'<tt>and</tt>' Instruction</h4><ul>
1043
1044<h5>Syntax:</h5>
1045<pre>
1046 &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1047</pre>
1048
1049<h5>Overview:</h5>
1050The '<tt>and</tt>' instruction returns the bitwise logical and of its two operands.<p>
1051
1052<h5>Arguments:</h5>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1053
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1054The two arguments to the '<tt>and</tt>' instruction must be <a
1055href="#t_integral">integral</a> values. Both arguments must have identical
1056types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1057
1058
1059<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1060
1061The truth table used for the '<tt>and</tt>' instruction is:<p>
1062
Chris Lattnerc98cbbc2002-06-25 18:06:50 +0000[diff] [blame]1063<center><table border=1 cellspacing=0 cellpadding=4>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1064<tr><td>In0</td> <td>In1</td> <td>Out</td></tr>
1065<tr><td>0</td> <td>0</td> <td>0</td></tr>
1066<tr><td>0</td> <td>1</td> <td>0</td></tr>
1067<tr><td>1</td> <td>0</td> <td>0</td></tr>
1068<tr><td>1</td> <td>1</td> <td>1</td></tr>
1069</table></center><p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1070
1071
1072<h5>Example:</h5>
1073<pre>
1074 &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 & %var</i>
1075 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1076 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1077</pre>
1078
1079
1080
1081<!-- _______________________________________________________________________ -->
1082</ul><a name="i_or"><h4><hr size=0>'<tt>or</tt>' Instruction</h4><ul>
1083
1084<h5>Syntax:</h5>
1085<pre>
1086 &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1087</pre>
1088
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1089<h5>Overview:</h5> The '<tt>or</tt>' instruction returns the bitwise logical
1090inclusive or of its two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1091
1092<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1093
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1094The two arguments to the '<tt>or</tt>' instruction must be <a
1095href="#t_integral">integral</a> values. Both arguments must have identical
1096types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1097
1098
1099<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1100
1101The truth table used for the '<tt>or</tt>' instruction is:<p>
1102
Chris Lattnerc98cbbc2002-06-25 18:06:50 +0000[diff] [blame]1103<center><table border=1 cellspacing=0 cellpadding=4>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1104<tr><td>In0</td> <td>In1</td> <td>Out</td></tr>
1105<tr><td>0</td> <td>0</td> <td>0</td></tr>
1106<tr><td>0</td> <td>1</td> <td>1</td></tr>
1107<tr><td>1</td> <td>0</td> <td>1</td></tr>
1108<tr><td>1</td> <td>1</td> <td>1</td></tr>
1109</table></center><p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1110
1111
1112<h5>Example:</h5>
1113<pre>
1114 &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
1115 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1116 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1117</pre>
1118
1119
1120<!-- _______________________________________________________________________ -->
1121</ul><a name="i_xor"><h4><hr size=0>'<tt>xor</tt>' Instruction</h4><ul>
1122
1123<h5>Syntax:</h5>
1124<pre>
1125 &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1126</pre>
1127
1128<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1129
1130The '<tt>xor</tt>' instruction returns the bitwise logical exclusive or of its
1131two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1132
1133<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1134
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1135The two arguments to the '<tt>xor</tt>' instruction must be <a
1136href="#t_integral">integral</a> values. Both arguments must have identical
1137types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1138
1139
1140<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1141
1142The truth table used for the '<tt>xor</tt>' instruction is:<p>
1143
Chris Lattnerc98cbbc2002-06-25 18:06:50 +0000[diff] [blame]1144<center><table border=1 cellspacing=0 cellpadding=4>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1145<tr><td>In0</td> <td>In1</td> <td>Out</td></tr>
1146<tr><td>0</td> <td>0</td> <td>0</td></tr>
1147<tr><td>0</td> <td>1</td> <td>1</td></tr>
1148<tr><td>1</td> <td>0</td> <td>1</td></tr>
1149<tr><td>1</td> <td>1</td> <td>0</td></tr>
1150</table></center><p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1151
1152
1153<h5>Example:</h5>
1154<pre>
1155 &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
1156 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1157 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
1158</pre>
1159
1160
1161<!-- _______________________________________________________________________ -->
1162</ul><a name="i_shl"><h4><hr size=0>'<tt>shl</tt>' Instruction</h4><ul>
1163
1164<h5>Syntax:</h5>
1165<pre>
1166 &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
1167</pre>
1168
1169<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1170
1171The '<tt>shl</tt>' instruction returns the first operand shifted to the left a
1172specified number of bits.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1173
1174<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1175
1176The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1177href="#t_integer">integer</a> type. The second argument must be an
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1178'<tt>ubyte</tt>' type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1179
1180<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1181
1182The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1183
1184
1185<h5>Example:</h5>
1186<pre>
1187 &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 << %var</i>
1188 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1189 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1190</pre>
1191
1192
1193<!-- _______________________________________________________________________ -->
1194</ul><a name="i_shr"><h4><hr size=0>'<tt>shr</tt>' Instruction</h4><ul>
1195
1196
1197<h5>Syntax:</h5>
1198<pre>
1199 &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
1200</pre>
1201
1202<h5>Overview:</h5>
1203The '<tt>shr</tt>' instruction returns the first operand shifted to the right a specified number of bits.
1204
1205<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1206The first argument to the '<tt>shr</tt>' instruction must be an <a href="#t_integer">integer</a> type. The second argument must be an '<tt>ubyte</tt>' type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1207
1208<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1209
1210If the first argument is a <a href="#t_signed">signed</a> type, the most
1211significant bit is duplicated in the newly free'd bit positions. If the first
1212argument is unsigned, zero bits shall fill the empty positions.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1213
1214<h5>Example:</h5>
1215<pre>
1216 &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 >> %var</i>
1217 &lt;result&gt; = shr int 4, ubyte 1 <i>; yields {int}:result = 2</i>
1218 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
1219 &lt;result&gt; = shr int 4, ubyte 3 <i>; yields {int}:result = 0</i>
1220</pre>
1221
1222
1223
1224
1225
1226<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1227</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1228<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1229<a name="memoryops">Memory Access Operations
1230</b></font></td></tr></table><ul>
1231
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1232Accessing memory in SSA form is, well, sticky at best. This section describes how to read, write, allocate and free memory in LLVM.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1233
1234
1235<!-- _______________________________________________________________________ -->
1236</ul><a name="i_malloc"><h4><hr size=0>'<tt>malloc</tt>' Instruction</h4><ul>
1237
1238<h5>Syntax:</h5>
1239<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1240 &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
1241 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1242</pre>
1243
1244<h5>Overview:</h5>
1245The '<tt>malloc</tt>' instruction allocates memory from the system heap and returns a pointer to it.<p>
1246
1247<h5>Arguments:</h5>
1248
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1249The the '<tt>malloc</tt>' instruction allocates
1250<tt>sizeof(&lt;type&gt;)*NumElements</tt> bytes of memory from the operating
1251system, and returns a pointer of the appropriate type to the program. The
1252second form of the instruction is a shorter version of the first instruction
1253that defaults to allocating one element.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1254
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1255'<tt>type</tt>' must be a sized type<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1256
1257<h5>Semantics:</h5>
1258Memory is allocated, a pointer is returned.<p>
1259
1260<h5>Example:</h5>
1261<pre>
1262 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
1263
1264 %size = <a 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>
1268
1269
1270<!-- _______________________________________________________________________ -->
1271</ul><a name="i_free"><h4><hr size=0>'<tt>free</tt>' Instruction</h4><ul>
1272
1273<h5>Syntax:</h5>
1274<pre>
1275 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
1276</pre>
1277
1278
1279<h5>Overview:</h5>
1280The '<tt>free</tt>' instruction returns memory back to the unused memory heap, to be reallocated in the future.<p>
1281
1282
1283<h5>Arguments:</h5>
1284
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1285'<tt>value</tt>' shall be a pointer value that points to a value that was
1286allocated with the '<tt><a href="#i_malloc">malloc</a></tt>' instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1287
1288
1289<h5>Semantics:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1290
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1291Access to the memory pointed to by the pointer is not longer defined after this instruction executes.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1292
1293<h5>Example:</h5>
1294<pre>
1295 %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
1296 free [4 x ubyte]* %array
1297</pre>
1298
1299
1300<!-- _______________________________________________________________________ -->
1301</ul><a name="i_alloca"><h4><hr size=0>'<tt>alloca</tt>' Instruction</h4><ul>
1302
1303<h5>Syntax:</h5>
1304<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1305 &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
1306 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1307</pre>
1308
1309<h5>Overview:</h5>
1310
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1311The '<tt>alloca</tt>' instruction allocates memory on the current stack frame of
1312the procedure that is live until the current function returns to its caller.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1313
1314<h5>Arguments:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1315
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1316The the '<tt>alloca</tt>' instruction allocates
1317<tt>sizeof(&lt;type&gt;)*NumElements</tt> bytes of memory on the runtime stack,
1318returning a pointer of the appropriate type to the program. The second form of
1319the instruction is a shorter version of the first that defaults to allocating
1320one element.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1321
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1322'<tt>type</tt>' may be any sized type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1323
1324<h5>Semantics:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1325
1326Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d memory is
1327automatically released when the function returns. The '<tt>alloca</tt>'
1328instruction is commonly used to represent automatic variables that must have an
1329address available, as well as spilled variables.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1330
1331<h5>Example:</h5>
1332<pre>
1333 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1334 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1335</pre>
1336
1337
1338<!-- _______________________________________________________________________ -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1339</ul><a name="i_load"><h4><hr size=0>'<tt>load</tt>' Instruction</h4><ul>
1340
1341<h5>Syntax:</h5>
1342<pre>
1343 &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;
1344</pre>
1345
1346<h5>Overview:</h5>
1347The '<tt>load</tt>' instruction is used to read from memory.<p>
1348
1349<h5>Arguments:</h5>
1350
1351The argument to the '<tt>load</tt>' instruction specifies the memory address to load from. The pointer must point to a <a href="t_firstclass">first class</a> type.<p>
1352
1353<h5>Semantics:</h5>
1354
1355The location of memory pointed to is loaded.
1356
1357<h5>Examples:</h5>
1358<pre>
1359 %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1360 <a href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
1361 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1362</pre>
1363
1364
1365
1366
1367<!-- _______________________________________________________________________ -->
1368</ul><a name="i_store"><h4><hr size=0>'<tt>store</tt>' Instruction</h4><ul>
1369
1370<h5>Syntax:</h5>
1371<pre>
1372 store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
1373</pre>
1374
1375<h5>Overview:</h5>
1376The '<tt>store</tt>' instruction is used to write to memory.<p>
1377
1378<h5>Arguments:</h5>
1379
1380There are two arguments to the '<tt>store</tt>' instruction: a value to store
1381and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1382operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
1383operand.<p>
1384
1385<h5>Semantics:</h5> The contents of memory are updated to contain
1386'<tt>&lt;value&gt;</tt>' at the location specified by the
1387'<tt>&lt;pointer&gt;</tt>' operand.<p>
1388
1389<h5>Example:</h5>
1390<pre>
1391 %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1392 <a href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
1393 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1394</pre>
1395
1396
1397
1398
1399<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1400</ul><a name="i_getelementptr"><h4><hr size=0>'<tt>getelementptr</tt>' Instruction</h4><ul>
1401
1402<h5>Syntax:</h5>
1403<pre>
1404 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, uint &lt;aidx&gt;|, ubyte &lt;sidx&gt;}*
1405</pre>
1406
1407<h5>Overview:</h5>
1408
1409The '<tt>getelementptr</tt>' instruction is used to get the address of a
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1410subelement of an aggregate data structure.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1411
1412<h5>Arguments:</h5>
1413
1414This instruction takes a list of <tt>uint</tt> values and <tt>ubyte</tt>
1415constants that indicate what form of addressing to perform. The actual types of
1416the arguments provided depend on the type of the first pointer argument. The
1417'<tt>getelementptr</tt>' instruction is used to index down through the type
1418levels of a structure.<p>
1419
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1420For example, lets consider a C code fragment and how it gets compiled to
1421LLVM:<p>
1422
1423<pre>
1424struct RT {
1425 char A;
1426 int B[10][20];
1427 char C;
1428};
1429struct ST {
1430 int X;
1431 double Y;
1432 struct RT Z;
1433};
1434
1435int *foo(struct ST *s) {
1436 return &amp;s[1].Z.B[5][13];
1437}
1438</pre>
1439
1440The LLVM code generated by the GCC frontend is:
1441
1442<pre>
1443%RT = type { sbyte, [10 x [20 x int]], sbyte }
1444%ST = type { int, double, %RT }
1445
1446int* "foo"(%ST* %s) {
1447 %reg = getelementptr %ST* %s, uint 1, ubyte 2, ubyte 1, uint 5, uint 13
1448 ret int* %reg
1449}
1450</pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1451
1452<h5>Semantics:</h5>
1453
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1454The index types specified for the '<tt>getelementptr</tt>' instruction depend on
1455the pointer type that is being index into. <a href="t_pointer">Pointer</a> and
1456<a href="t_array">array</a> types require '<tt>uint</tt>' values, and <a
1457href="t_struct">structure</a> types require '<tt>ubyte</tt>'
1458<b>constants</b>.<p>
1459
1460In the example above, the first index is indexing into the '<tt>%ST*</tt>' type,
1461which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT }</tt>'
1462type, a structure. The second index indexes into the third element of the
1463structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]], sbyte
1464}</tt>' type, another structure. The third index indexes into the second
1465element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
1466array. The two dimensions of the array are subscripted into, yielding an
1467'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction return a pointer
1468to this element, thus yielding a '<tt>int*</tt>' type.<p>
1469
1470Note that it is perfectly legal to index partially through a structure,
1471returning a pointer to an inner element. Because of this, the LLVM code for the
1472given testcase is equivalent to:<p>
1473
1474<pre>
1475int* "foo"(%ST* %s) {
1476 %t1 = getelementptr %ST* %s , uint 1 <i>; yields %ST*:%t1</i>
1477 %t2 = getelementptr %ST* %t1, uint 0, ubyte 2 <i>; yields %RT*:%t2</i>
1478 %t3 = getelementptr %RT* %t2, uint 0, ubyte 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1479 %t4 = getelementptr [10 x [20 x int]]* %t3, uint 0, uint 5 <i>; yields [20 x int]*:%t4</i>
1480 %t5 = getelementptr [20 x int]* %t4, uint 0, uint 13 <i>; yields int*:%t5</i>
1481 ret int* %t5
1482}
1483</pre>
1484
1485
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1486
1487<h5>Example:</h5>
1488<pre>
Chris Lattnerf31860b2002-08-19 21:14:38 +0000[diff] [blame]1489 <i>; yields [12 x ubyte]*:aptr</i>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1490 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, uint 0, ubyte 1
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1491</pre>
1492
1493
1494
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1495<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1496</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1497<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1498<a name="otherops">Other Operations
1499</b></font></td></tr></table><ul>
1500
1501The instructions in this catagory are the "miscellaneous" functions, that defy better classification.<p>
1502
1503
1504<!-- _______________________________________________________________________ -->
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1505</ul><a name="i_phi"><h4><hr size=0>'<tt>phi</tt>' Instruction</h4><ul>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1506
1507<h5>Syntax:</h5>
1508<pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1509 &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1510</pre>
1511
1512<h5>Overview:</h5>
1513
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1514The '<tt>phi</tt>' instruction is used to implement the &phi; node in the SSA
1515graph representing the function.<p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1516
1517<h5>Arguments:</h5>
1518
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1519The type of the incoming values are specified with the first type field. After
1520this, the '<tt>phi</tt>' instruction takes a list of pairs as arguments, with
1521one pair for each predecessor basic block of the current block.<p>
1522
1523There must be no non-phi instructions between the start of a basic block and the
1524PHI instructions: i.e. PHI instructions must be first in a basic block.<p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1525
1526<h5>Semantics:</h5>
1527
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1528At runtime, the '<tt>phi</tt>' instruction logically takes on the value
1529specified by the parameter, depending on which basic block we came from in the
1530last <a href="#terminators">terminator</a> instruction.<p>
1531
1532<h5>Example:</h5>
1533
1534<pre>
1535Loop: ; Infinite loop that counts from 0 on up...
1536 %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
1537 %nextindvar = add uint %indvar, 1
1538 br label %Loop
1539</pre>
1540
1541
1542<!-- _______________________________________________________________________ -->
1543</ul><a name="i_cast"><h4><hr size=0>'<tt>cast .. to</tt>' Instruction</h4><ul>
1544
1545<h5>Syntax:</h5>
1546<pre>
1547 &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
1548</pre>
1549
1550<h5>Overview:</h5>
1551
1552The '<tt>cast</tt>' instruction is used as the primitive means to convert
1553integers to floating point, change data type sizes, and break type safety (by
1554casting pointers).<p>
1555
1556<h5>Arguments:</h5>
1557
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1558The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1559class value, and a type to cast it to, which must also be a first class type.<p>
1560
1561<h5>Semantics:</h5>
1562
1563This instruction follows the C rules for explicit casts when determining how the
1564data being cast must change to fit in its new container.<p>
1565
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1566When casting to bool, any value that would be considered true in the context of
1567a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
1568all else are '<tt>false</tt>'.<p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1569
Chris Lattnerf8856bc2002-08-13 20:52:09 +0000[diff] [blame]1570When extending an integral value from a type of one signness to another (for
1571example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
1572<b>source</b> value is signed, and zero-extended if the source value is
Chris Lattner2b4dcbb2002-08-15 19:36:05 +0000[diff] [blame]1573unsigned. <tt>bool</tt> values are always zero extended into either zero or
1574one.<p>
Chris Lattnerf8856bc2002-08-13 20:52:09 +0000[diff] [blame]1575
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1576<h5>Example:</h5>
1577<pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1578 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1579 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1580</pre>
1581
1582
1583
1584<!-- _______________________________________________________________________ -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1585</ul><a name="i_call"><h4><hr size=0>'<tt>call</tt>' Instruction</h4><ul>
1586
1587<h5>Syntax:</h5>
1588<pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1589 &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1590</pre>
1591
1592<h5>Overview:</h5>
1593
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1594The '<tt>call</tt>' instruction represents a simple function call.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1595
1596<h5>Arguments:</h5>
1597
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1598This instruction requires several arguments:<p>
1599<ol>
1600
1601<li>'<tt>ty</tt>': shall be the signature of the pointer to function value being
1602invoked. The argument types must match the types implied by this signature.<p>
1603
1604<li>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to be
1605invoked. In most cases, this is a direct function invocation, but indirect
Misha Brukmane6fe6712002-09-18 02:35:14 +0000[diff] [blame]1606<tt>call</tt>s are just as possible, calling an arbitrary pointer to function
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1607values.<p>
1608
1609<li>'<tt>function args</tt>': argument list whose types match the function
1610signature argument types. If the function signature indicates the function
1611accepts a variable number of arguments, the extra arguments can be specified.
1612</ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1613
1614<h5>Semantics:</h5>
1615
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1616The '<tt>call</tt>' instruction is used to cause control flow to transfer to a
1617specified function, with its incoming arguments bound to the specified values.
1618Upon a '<tt><a href="#i_ret">ret</a></tt>' instruction in the called function,
1619control flow continues with the instruction after the function call, and the
1620return value of the function is bound to the result argument. This is a simpler
1621case of the <a href="#i_invoke">invoke</a> instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1622
1623<h5>Example:</h5>
1624<pre>
1625 %retval = call int %test(int %argc)
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1626 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
1627
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1628</pre>
1629
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1630<!--
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1631
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1632<!x- *********************************************************************** -x>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1633</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
1634<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1635<a name="related">Related Work
1636</b></font></td></tr></table><ul>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1637<!x- *********************************************************************** -x>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1638
1639
1640Codesigned virtual machines.<p>
1641
1642<dl>
1643<a name="rw_safetsa">
1644<dt>SafeTSA
1645<DD>Description here<p>
1646
1647<a name="rw_java">
1648<dt><a href="http://www.javasoft.com">Java</a>
1649<DD>Desciption here<p>
1650
1651<a name="rw_net">
1652<dt><a href="http://www.microsoft.com/net">Microsoft .net</a>
1653<DD>Desciption here<p>
1654
1655<a name="rw_gccrtl">
1656<dt><a href="http://www.math.umn.edu/systems_guide/gcc-2.95.1/gcc_15.html">GNU RTL Intermediate Representation</a>
1657<DD>Desciption here<p>
1658
1659<a name="rw_ia64">
1660<dt><a href="http://developer.intel.com/design/ia-64/index.htm">IA64 Architecture &amp; Instruction Set</a>
1661<DD>Desciption here<p>
1662
1663<a name="rw_mmix">
1664<dt><a href="http://www-cs-faculty.stanford.edu/~knuth/mmix-news.html">MMIX Instruction Set</a>
1665<DD>Desciption here<p>
1666
1667<a name="rw_stroustrup">
1668<dt><a href="http://www.research.att.com/~bs/devXinterview.html">"Interview With Bjarne Stroustrup"</a>
1669<DD>This interview influenced the design and thought process behind LLVM in several ways, most notably the way that derived types are written in text format. See the question that starts with "you defined the C declarator syntax as an experiment that failed".<p>
1670</dl>
1671
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1672<!x- _______________________________________________________________________ -x>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1673</ul><a name="rw_vectorization"><h3><hr size=0>Vectorized Architectures</h3><ul>
1674
1675<dl>
1676<a name="rw_intel_simd">
1677<dt>Intel MMX, MMX2, SSE, SSE2
1678<DD>Description here<p>
1679
1680<a name="rw_amd_simd">
1681<dt><a href="http://www.nondot.org/~sabre/os/H1ChipFeatures/3DNow!TechnologyManual.pdf">AMD 3Dnow!, 3Dnow! 2</a>
1682<DD>Desciption here<p>
1683
1684<a name="rw_sun_simd">
1685<dt><a href="http://www.nondot.org/~sabre/os/H1ChipFeatures/VISInstructionSetUsersManual.pdf">Sun VIS ISA</a>
1686<DD>Desciption here<p>
1687
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1688<a name="rw_powerpc_simd">
1689<dt>PowerPC Altivec
1690<DD>Desciption here<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1691
1692</dl>
1693
1694more...
1695
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1696-->
1697
1698
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1699<!-- *********************************************************************** -->
1700</ul>
1701<!-- *********************************************************************** -->
1702
1703
1704<hr>
1705<font size=-1>
1706<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1707<!-- Created: Tue Jan 23 15:19:28 CST 2001 -->
1708<!-- hhmts start -->
Chris Lattnera0ff4aa2002-11-05 00:21:03 +0000[diff] [blame^]1709Last modified: Mon Nov 4 18:20:38 CST 2002
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1710<!-- hhmts end -->
1711</font>
1712</body></html>