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Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]2<html><head><title>LLVM Assembly Language Reference Manual</title></head>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]3<body bgcolor=white>
4
5<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]6<tr><td>&nbsp; <font size=+5 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>LLVM Language Reference Manual</b></font></td>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]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 Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]74 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]75 </ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]76 </ol>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]77 <li><a href="#intrinsics">Intrinsic Functions</a>
78 <ol>
79 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
80 <ol>
81 <li><a href="#i_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
82 <li><a href="#i_va_end" >'<tt>llvm.va_end</tt>' Intrinsic</a>
83 <li><a href="#i_va_copy" >'<tt>llvm.va_copy</tt>' Intrinsic</a>
84 </ol>
85 </ol>
Chris Lattnerd816bcf2002-08-30 21:50:21 +0000[diff] [blame]86
87 <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>
88
89
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]90</ol>
91
92
93<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]94<p><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
95<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]96<a name="abstract">Abstract
97</b></font></td></tr></table><ul>
98<!-- *********************************************************************** -->
99
100<blockquote>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]101 This document is a reference manual for the LLVM assembly language. LLVM is
102 an SSA based representation that provides type safety, low level operations,
103 flexibility, and the capability of representing 'all' high level languages
104 cleanly. It is the common code representation used throughout all phases of
105 the LLVM compilation strategy.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]106</blockquote>
107
108
109
110
111<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]112</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
113<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]114<a name="introduction">Introduction
115</b></font></td></tr></table><ul>
116<!-- *********************************************************************** -->
117
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]118The LLVM code representation is designed to be used in three different forms: as
119an in-memory compiler IR, as an on-disk bytecode representation, suitable for
120fast loading by a dynamic compiler, and as a human readable assembly language
121representation. This allows LLVM to provide a powerful intermediate
122representation for efficient compiler transformations and analysis, while
123providing a natural means to debug and visualize the transformations. The three
124different forms of LLVM are all equivalent. This document describes the human
125readable representation and notation.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]126
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]127The LLVM representation aims to be a light weight and low level while being
Chris Lattnerb7c6c2a2002-06-25 20:20:08 +0000[diff] [blame]128expressive, typed, and extensible at the same time. It aims to be a "universal
129IR" of sorts, by being at a low enough level that high level ideas may be
130cleanly mapped to it (similar to how microprocessors are "universal IR's",
131allowing many source languages to be mapped to them). By providing type
132information, LLVM can be used as the target of optimizations: for example,
133through pointer analysis, it can be proven that a C automatic variable is never
134accessed outside of the current function... allowing it to be promoted to a
135simple SSA value instead of a memory location.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]136
137<!-- _______________________________________________________________________ -->
138</ul><a name="wellformed"><h4><hr size=0>Well Formedness</h4><ul>
139
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]140It is important to note that this document describes 'well formed' LLVM assembly
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]141language. There is a difference between what the parser accepts and what is
142considered 'well formed'. For example, the following instruction is
143syntactically okay, but not well formed:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]144
145<pre>
146 %x = <a href="#i_add">add</a> int 1, %x
147</pre>
148
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]149...because the definition of <tt>%x</tt> does not dominate all of its uses. The
150LLVM infrastructure provides a verification pass that may be used to verify that
151an LLVM module is well formed. This pass is automatically run by the parser
152after parsing input assembly, and by the optimizer before it outputs bytecode.
153The violations pointed out by the verifier pass indicate bugs in transformation
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]154passes or input to the parser.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]155
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]156<!-- Describe the typesetting conventions here. -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]157
158
159<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]160</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
161<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]162<a name="identifiers">Identifiers
163</b></font></td></tr></table><ul>
164<!-- *********************************************************************** -->
165
166LLVM uses three different forms of identifiers, for different purposes:<p>
167
168<ol>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]169<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]170<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>'.
171<li>Unnamed values are represented as an unsigned numeric value with a '%' prefix. For example, %12, %2, %44.
172</ol><p>
173
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]174LLVM requires the values start with a '%' sign for two reasons: Compilers don't
175need to worry about name clashes with reserved words, and the set of reserved
176words may be expanded in the future without penalty. Additionally, unnamed
177identifiers allow a compiler to quickly come up with a temporary variable
178without having to avoid symbol table conflicts.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]179
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]180Reserved words in LLVM are very similar to reserved words in other languages.
181There are keywords for different opcodes ('<tt><a href="#i_add">add</a></tt>',
182'<tt><a href="#i_cast">cast</a></tt>', '<tt><a href="#i_ret">ret</a></tt>',
183etc...), for primitive type names ('<tt><a href="#t_void">void</a></tt>',
184'<tt><a href="#t_uint">uint</a></tt>', etc...), and others. These reserved
185words cannot conflict with variable names, because none of them start with a '%'
186character.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]187
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]188Here is an example of LLVM code to multiply the integer variable '<tt>%X</tt>'
189by 8:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]190
191The easy way:
192<pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]193 %result = <a href="#i_mul">mul</a> uint %X, 8
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]194</pre>
195
196After strength reduction:
197<pre>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]198 %result = <a href="#i_shl">shl</a> uint %X, ubyte 3
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]199</pre>
200
201And the hard way:
202<pre>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]203 <a href="#i_add">add</a> uint %X, %X <i>; yields {uint}:%0</i>
204 <a href="#i_add">add</a> uint %0, %0 <i>; yields {uint}:%1</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]205 %result = <a href="#i_add">add</a> uint %1, %1
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]206</pre>
207
208This last way of multiplying <tt>%X</tt> by 8 illustrates several important lexical features of LLVM:<p>
209
210<ol>
211<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]212<li>Unnamed temporaries are created when the result of a computation is not
213 assigned to a named value.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]214<li>Unnamed temporaries are numbered sequentially
215</ol><p>
216
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]217...and it also show a convention that we follow in this document. When
218demonstrating instructions, we will follow an instruction with a comment that
219defines the type and name of value produced. Comments are shown in italic
220text.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]221
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]222The one non-intuitive notation for constants is the optional hexidecimal form of
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]223floating point constants. For example, the form '<tt>double
2240x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
2254.5e+15</tt>' which is also supported by the parser. The only time hexadecimal
226floating point constants are useful (and the only time that they are generated
227by the disassembler) is when an FP constant has to be emitted that is not
228representable as a decimal floating point number exactly. For example, NaN's,
229infinities, and other special cases are represented in their IEEE hexadecimal
230format so that assembly and disassembly do not cause any bits to change in the
231constants.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]232
233
234<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]235</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
236<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]237<a name="typesystem">Type System
238</b></font></td></tr></table><ul>
239<!-- *********************************************************************** -->
240
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]241The LLVM type system is one of the most important features of the intermediate
Chris Lattnerb7c6c2a2002-06-25 20:20:08 +0000[diff] [blame]242representation. Being typed enables a number of optimizations to be performed
243on the IR directly, without having to do extra analyses on the side before the
244transformation. A strong type system makes it easier to read the generated code
245and enables novel analyses and transformations that are not feasible to perform
246on normal three address code representations.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]247
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]248<!-- The written form for the type system was heavily influenced by the
249syntactic problems with types in the C language<sup><a
250href="#rw_stroustrup">1</a></sup>.<p> -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]251
252
253
254<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]255</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
256<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]257<a name="t_primitive">Primitive Types
258</b></font></td></tr></table><ul>
259
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]260The primitive types are the fundemental building blocks of the LLVM system. The
261current set of primitive types are as follows:<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]262
263<table border=0 align=center><tr><td>
264
265<table border=1 cellspacing=0 cellpadding=4 align=center>
266<tr><td><tt>void</tt></td> <td>No value</td></tr>
267<tr><td><tt>ubyte</tt></td> <td>Unsigned 8 bit value</td></tr>
268<tr><td><tt>ushort</tt></td><td>Unsigned 16 bit value</td></tr>
269<tr><td><tt>uint</tt></td> <td>Unsigned 32 bit value</td></tr>
270<tr><td><tt>ulong</tt></td> <td>Unsigned 64 bit value</td></tr>
271<tr><td><tt>float</tt></td> <td>32 bit floating point value</td></tr>
272<tr><td><tt>label</tt></td> <td>Branch destination</td></tr>
273</table>
274
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]275</td><td valign=top>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]276
277<table border=1 cellspacing=0 cellpadding=4 align=center>
278<tr><td><tt>bool</tt></td> <td>True or False value</td></tr>
279<tr><td><tt>sbyte</tt></td> <td>Signed 8 bit value</td></tr>
280<tr><td><tt>short</tt></td> <td>Signed 16 bit value</td></tr>
281<tr><td><tt>int</tt></td> <td>Signed 32 bit value</td></tr>
282<tr><td><tt>long</tt></td> <td>Signed 64 bit value</td></tr>
283<tr><td><tt>double</tt></td><td>64 bit floating point value</td></tr>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]284</table>
285
286</td></tr></table><p>
287
288
289
290<!-- _______________________________________________________________________ -->
291</ul><a name="t_classifications"><h4><hr size=0>Type Classifications</h4><ul>
292
293These different primitive types fall into a few useful classifications:<p>
294
295<table border=1 cellspacing=0 cellpadding=4 align=center>
296<tr><td><a name="t_signed">signed</td> <td><tt>sbyte, short, int, long, float, double</tt></td></tr>
297<tr><td><a name="t_unsigned">unsigned</td><td><tt>ubyte, ushort, uint, ulong</tt></td></tr>
Chris Lattnerb5561ff2003-06-18 21:28:11 +0000[diff] [blame]298<tr><td><a name="t_integer">integer</td><td><tt>ubyte, sbyte, ushort, short, uint, int, ulong, long</tt></td></tr>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]299<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]300<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]301<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]302</table><p>
303
304
305
306
307
308<!-- ======================================================================= -->
309</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>
310<a name="t_derived">Derived Types
311</b></font></td></tr></table><ul>
312
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]313The real power in LLVM comes from the derived types in the system. This is what
314allows a programmer to represent arrays, functions, pointers, and other useful
315types. Note that these derived types may be recursive: For example, it is
316possible to have a two dimensional array.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]317
318
319
320<!-- _______________________________________________________________________ -->
321</ul><a name="t_array"><h4><hr size=0>Array Type</h4><ul>
322
323<h5>Overview:</h5>
324
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]325The array type is a very simple derived type that arranges elements sequentially
326in memory. The array type requires a size (number of elements) and an
327underlying data type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]328
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]329<h5>Syntax:</h5>
330<pre>
331 [&lt;# elements&gt; x &lt;elementtype&gt;]
332</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]333
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]334The number of elements is a constant integer value, elementtype may be any type
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]335with a size.<p>
336
337<h5>Examples:</h5>
338<ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]339 <tt>[40 x int ]</tt>: Array of 40 integer values.<br>
340 <tt>[41 x int ]</tt>: Array of 41 integer values.<br>
341 <tt>[40 x uint]</tt>: Array of 40 unsigned integer values.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]342</ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]343
344Here are some examples of multidimensional arrays:<p>
345<ul>
346<table border=0 cellpadding=0 cellspacing=0>
347<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]348<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]349<tr><td><tt>[2 x [3 x [4 x uint]]]</tt></td><td>: 2x3x4 array of unsigned integer values.</td></tr>
350</table>
351</ul>
352
353
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]354<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]355</ul><a name="t_function"><h4><hr size=0>Function Type</h4><ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]356
357<h5>Overview:</h5>
358
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]359The function type can be thought of as a function signature. It consists of a
360return type and a list of formal parameter types. Function types are usually
361used when to build virtual function tables (which are structures of pointers to
362functions), for indirect function calls, and when defining a function.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]363
364<h5>Syntax:</h5>
365<pre>
366 &lt;returntype&gt; (&lt;parameter list&gt;)
367</pre>
368
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]369Where '<tt>&lt;parameter list&gt;</tt>' is a comma seperated list of type
370specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
371which indicates that the function takes a variable number of arguments. Note
372that there currently is no way to define a function in LLVM that takes a
373variable number of arguments, but it is possible to <b>call</b> a function that
374is vararg.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]375
376<h5>Examples:</h5>
377<ul>
378<table border=0 cellpadding=0 cellspacing=0>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]379
380<tr><td><tt>int (int)</tt></td><td>: function taking an <tt>int</tt>, returning
381an <tt>int</tt></td></tr>
382
383<tr><td><tt>float (int, int *) *</tt></td><td>: <a href="#t_pointer">Pointer</a>
384to a function that takes an <tt>int</tt> and a <a href="#t_pointer">pointer</a>
385to <tt>int</tt>, returning <tt>float</tt>.</td></tr>
386
387<tr><td><tt>int (sbyte *, ...)</tt></td><td>: A vararg function that takes at
388least one <a href="#t_pointer">pointer</a> to <tt>sbyte</tt> (signed char in C),
389which returns an integer. This is the signature for <tt>printf</tt> in
390LLVM.</td></tr>
391
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]392</table>
393</ul>
394
395
396
397<!-- _______________________________________________________________________ -->
398</ul><a name="t_struct"><h4><hr size=0>Structure Type</h4><ul>
399
400<h5>Overview:</h5>
401
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]402The structure type is used to represent a collection of data members together in
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]403memory. The packing of the field types is defined to match the ABI of the
404underlying processor. The elements of a structure may be any type that has a
405size.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]406
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]407Structures are accessed using '<tt><a href="#i_load">load</a></tt> and '<tt><a
408href="#i_store">store</a></tt>' by getting a pointer to a field with the '<tt><a
409href="#i_getelementptr">getelementptr</a></tt>' instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]410
411<h5>Syntax:</h5>
412<pre>
413 { &lt;type list&gt; }
414</pre>
415
416
417<h5>Examples:</h5>
418<table border=0 cellpadding=0 cellspacing=0>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]419
420<tr><td><tt>{ int, int, int }</tt></td><td>: a triple of three <tt>int</tt>
421values</td></tr>
422
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]423<tr><td><tt>{ float, int (int) * }</tt></td><td>: A pair, where the first
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]424element is a <tt>float</tt> and the second element is a <a
425href="#t_pointer">pointer</a> to a <a href="t_function">function</a> that takes
426an <tt>int</tt>, returning an <tt>int</tt>.</td></tr>
427
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]428</table>
429
430
431<!-- _______________________________________________________________________ -->
432</ul><a name="t_pointer"><h4><hr size=0>Pointer Type</h4><ul>
433
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]434<h5>Overview:</h5>
435
436As in many languages, the pointer type represents a pointer or reference to
437another object, which must live in memory.<p>
438
439<h5>Syntax:</h5>
440<pre>
441 &lt;type&gt; *
442</pre>
443
444<h5>Examples:</h5>
445
446<table border=0 cellpadding=0 cellspacing=0>
447
448<tr><td><tt>[4x int]*</tt></td><td>: <a href="#t_pointer">pointer</a> to <a
449href="#t_array">array</a> of four <tt>int</tt> values</td></tr>
450
451<tr><td><tt>int (int *) *</tt></td><td>: A <a href="#t_pointer">pointer</a> to a
452<a href="t_function">function</a> that takes an <tt>int</tt>, returning an
453<tt>int</tt>.</td></tr>
454
455</table>
456<p>
457
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]458
459<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]460<!--
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]461</ul><a name="t_packed"><h4><hr size=0>Packed Type</h4><ul>
462
463Mention/decide that packed types work with saturation or not. Maybe have a packed+saturated type in addition to just a packed type.<p>
464
465Packed types should be 'nonsaturated' because standard data types are not saturated. Maybe have a saturated packed type?<p>
466
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]467-->
468
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]469
470<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]471</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
472<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]473<a name="highlevel">High Level Structure
474</b></font></td></tr></table><ul>
475<!-- *********************************************************************** -->
476
477
478<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]479</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
480<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]481<a name="modulestructure">Module Structure
482</b></font></td></tr></table><ul>
483
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]484LLVM programs are composed of "Module"s, each of which is a translation unit of
485the input programs. Each module consists of functions, global variables, and
486symbol table entries. Modules may be combined together with the LLVM linker,
487which merges function (and global variable) definitions, resolves forward
488declarations, 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]489
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]490<pre>
491<i>; Declare the string constant as a global constant...</i>
492<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>
493
494<i>; Forward declaration of puts</i>
495<a href="#functionstructure">declare</a> int "puts"(sbyte*) <i>; int(sbyte*)* </i>
496
497<i>; Definition of main function</i>
498int "main"() { <i>; int()* </i>
499 <i>; Convert [13x sbyte]* to sbyte *...</i>
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]500 %cast210 = <a href="#i_getelementptr">getelementptr</a> [13 x sbyte]* %.LC0, long 0, long 0 <i>; sbyte*</i>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]501
502 <i>; Call puts function to write out the string to stdout...</i>
503 <a href="#i_call">call</a> int %puts(sbyte* %cast210) <i>; int</i>
504 <a href="#i_ret">ret</a> int 0
505}
506</pre>
507
508This example is made up of a <a href="#globalvars">global variable</a> named
509"<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>" function, and a
510<a href="#functionstructure">function definition</a> for "<tt>main</tt>".<p>
511
512<a name="linkage_decl">
513In general, a module is made up of a list of global values, where both functions
514and global variables are global values. Global values are represented by a
515pointer to a memory location (in this case, a pointer to an array of char, and a
516pointer to a function), and can be either "internal" or externally accessible
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]517(which corresponds to the static keyword in C, when used at global scope).<p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]518
519For example, since the "<tt>.LC0</tt>" variable is defined to be internal, if
520another module defined a "<tt>.LC0</tt>" variable and was linked with this one,
521one of the two would be renamed, preventing a collision. Since "<tt>main</tt>"
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]522and "<tt>puts</tt>" are external (i.e., lacking "<tt>internal</tt>"
523declarations), they are accessible outside of the current module. It is illegal
524for a function declaration to be "<tt>internal</tt>".<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]525
526
527<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]528</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
529<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
530<a name="globalvars">Global Variables
531</b></font></td></tr></table><ul>
532
533Global variables define regions of memory allocated at compilation time instead
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]534of run-time. Global variables may optionally be initialized. A variable may
535be defined as a global "constant", which indicates that the contents of the
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]536variable will never be modified (opening options for optimization). Constants
537must always have an initial value.<p>
538
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]539As SSA values, global variables define pointer values that are in scope
540(i.e. they dominate) for all basic blocks in the program. Global variables
541always define a pointer to their "content" type because they describe a region
542of memory, and all memory objects in LLVM are accessed through pointers.<p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]543
544
545
546<!-- ======================================================================= -->
547</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
548<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]549<a name="functionstructure">Function Structure
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]550</b></font></td></tr></table><ul>
551
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]552LLVM functions definitions are composed of a (possibly empty) argument list, an
553opening curly brace, a list of basic blocks, and a closing curly brace. LLVM
554function declarations are defined with the "<tt>declare</tt>" keyword, a
555function name and a function signature.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]556
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]557A function definition contains a list of basic blocks, forming the CFG for the
558function. Each basic block may optionally start with a label (giving the basic
559block a symbol table entry), contains a list of instructions, and ends with a <a
560href="#terminators">terminator</a> instruction (such as a branch or function
561return).<p>
562
563The first basic block in program is special in two ways: it is immediately
564executed on entrance to the function, and it is not allowed to have predecessor
565basic blocks (i.e. there can not be any branches to the entry block of a
566function).<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]567
568
569<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]570</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
571<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]572<a name="instref">Instruction Reference
573</b></font></td></tr></table><ul>
574<!-- *********************************************************************** -->
575
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]576The LLVM instruction set consists of several different classifications of
Chris Lattnere489aa52002-08-14 17:55:59 +0000[diff] [blame]577instructions: <a href="#terminators">terminator instructions</a>, <a
578href="#binaryops">binary instructions</a>, <a href="#memoryops">memory
579instructions</a>, and <a href="#otherops">other instructions</a>.<p>
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]580
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]581
582<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]583</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
584<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]585<a name="terminators">Terminator Instructions
586</b></font></td></tr></table><ul>
587
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]588As mentioned <a href="#functionstructure">previously</a>, every basic block in a
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]589program ends with a "Terminator" instruction, which indicates which block should
590be executed after the current block is finished. These terminator instructions
591typically yield a '<tt>void</tt>' value: they produce control flow, not values
592(the one exception being the '<a href="#i_invoke"><tt>invoke</tt></a>'
593instruction).<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]594
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]595There are four different terminator instructions: the '<a
596href="#i_ret"><tt>ret</tt></a>' instruction, the '<a
597href="#i_br"><tt>br</tt></a>' instruction, the '<a
598href="#i_switch"><tt>switch</tt></a>' instruction, and the '<a
599href="#i_invoke"><tt>invoke</tt></a>' instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]600
601
602<!-- _______________________________________________________________________ -->
603</ul><a name="i_ret"><h4><hr size=0>'<tt>ret</tt>' Instruction</h4><ul>
604
605<h5>Syntax:</h5>
606<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]607 ret &lt;type&gt; &lt;value&gt; <i>; Return a value from a non-void function</i>
608 ret void <i>; Return from void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]609</pre>
610
611<h5>Overview:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]612
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]613The '<tt>ret</tt>' instruction is used to return control flow (and a value) from
614a function, back to the caller.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]615
616There are two forms of the '<tt>ret</tt>' instructruction: one that returns a
617value and then causes control flow, and one that just causes control flow to
618occur.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]619
620<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]621
622The '<tt>ret</tt>' instruction may return any '<a href="#t_firstclass">first
623class</a>' type. Notice that a function is not <a href="#wellformed">well
624formed</a> if there exists a '<tt>ret</tt>' instruction inside of the function
625that returns a value that does not match the return type of the function.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]626
627<h5>Semantics:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]628
629When the '<tt>ret</tt>' instruction is executed, control flow returns back to
630the calling function's context. If the instruction returns a value, that value
Misha Brukmana3bbcb52002-10-29 23:06:16 +0000[diff] [blame]631shall be propagated into the calling function's data space.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]632
633<h5>Example:</h5>
634<pre>
635 ret int 5 <i>; Return an integer value of 5</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]636 ret void <i>; Return from a void function</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]637</pre>
638
639
640<!-- _______________________________________________________________________ -->
641</ul><a name="i_br"><h4><hr size=0>'<tt>br</tt>' Instruction</h4><ul>
642
643<h5>Syntax:</h5>
644<pre>
645 br bool &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;
646 br label &lt;dest&gt; <i>; Unconditional branch</i>
647</pre>
648
649<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]650
651The '<tt>br</tt>' instruction is used to cause control flow to transfer to a
652different basic block in the current function. There are two forms of this
653instruction, corresponding to a conditional branch and an unconditional
654branch.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]655
656<h5>Arguments:</h5>
657
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]658The conditional branch form of the '<tt>br</tt>' instruction takes a single
659'<tt>bool</tt>' value and two '<tt>label</tt>' values. The unconditional form
660of the '<tt>br</tt>' instruction takes a single '<tt>label</tt>' value as a
661target.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]662
663<h5>Semantics:</h5>
664
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]665Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>bool</tt>'
666argument is evaluated. If the value is <tt>true</tt>, control flows to the
667'<tt>iftrue</tt>' '<tt>label</tt>' argument. If "cond" is <tt>false</tt>,
668control flows to the '<tt>iffalse</tt>' '<tt>label</tt>' argument.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]669
670<h5>Example:</h5>
671<pre>
672Test:
673 %cond = <a href="#i_setcc">seteq</a> int %a, %b
674 br bool %cond, label %IfEqual, label %IfUnequal
675IfEqual:
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]676 <a href="#i_ret">ret</a> int 1
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]677IfUnequal:
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]678 <a href="#i_ret">ret</a> int 0
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]679</pre>
680
681
682<!-- _______________________________________________________________________ -->
683</ul><a name="i_switch"><h4><hr size=0>'<tt>switch</tt>' Instruction</h4><ul>
684
685<h5>Syntax:</h5>
686<pre>
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]687 switch int &lt;value&gt;, label &lt;defaultdest&gt; [ int &lt;val&gt;, label &dest&gt;, ... ]
Chris Lattner00950542001-06-06 20:29:01 +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 Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]693The '<tt>switch</tt>' instruction is used to transfer control flow to one of
694several different places. It is a generalization of the '<tt>br</tt>'
695instruction, allowing a branch to occur to one of many possible destinations.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]696
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]697<h5>Arguments:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]698
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]699The '<tt>switch</tt>' instruction uses three parameters: a '<tt>uint</tt>'
700comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
701an array of pairs of comparison value constants and '<tt>label</tt>'s.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]702
703<h5>Semantics:</h5>
704
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]705The <tt>switch</tt> instruction specifies a table of values and destinations.
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]706When the '<tt>switch</tt>' instruction is executed, this table is searched for
707the given value. If the value is found, the corresponding destination is
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]708branched to, otherwise the default value it transfered to.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]709
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]710<h5>Implementation:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]711
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]712Depending on properties of the target machine and the particular <tt>switch</tt>
713instruction, this instruction may be code generated as a series of chained
714conditional branches, or with a lookup table.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]715
716<h5>Example:</h5>
717<pre>
718 <i>; Emulate a conditional br instruction</i>
719 %Val = <a href="#i_cast">cast</a> bool %value to uint
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]720 switch int %Val, label %truedest [int 0, label %falsedest ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]721
722 <i>; Emulate an unconditional br instruction</i>
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]723 switch int 0, label %dest [ ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]724
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]725 <i>; Implement a jump table:</i>
Chris Lattnerc29b1252003-05-08 05:08:48 +0000[diff] [blame]726 switch int %val, label %otherwise [ int 0, label %onzero,
727 int 1, label %onone,
728 int 2, label %ontwo ]
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]729</pre>
730
731
732
733<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]734</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]735
736<h5>Syntax:</h5>
737<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]738 &lt;result&gt; = invoke &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;)
739 to label &lt;normal label&gt; except label &lt;exception label&gt;
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]740</pre>
741
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]742<h5>Overview:</h5>
743
744The '<tt>invoke</tt>' instruction is used to cause control flow to transfer to a
745specified function, with the possibility of control flow transfer to either the
746'<tt>normal label</tt>' label or the '<tt>exception label</tt>'. The '<tt><a
747href="#i_call">call</a></tt>' instruction is closely related, but guarantees
748that control flow either never returns from the called function, or that it
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]749returns to the instruction following the '<tt><a href="#i_call">call</a></tt>'
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]750instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]751
752<h5>Arguments:</h5>
753
754This instruction requires several arguments:<p>
755<ol>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]756
757<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]758function value being invoked. In most cases, this is a direct function
Misha Brukmane6fe6712002-09-18 02:35:14 +0000[diff] [blame]759invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]760an arbitrary pointer to function value.<p>
761
762<li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
763function to be invoked.
764
765<li>'<tt>function args</tt>': argument list whose types match the function
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]766signature argument types. If the function signature indicates the function
767accepts a variable number of arguments, the extra arguments can be specified.
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]768
769<li>'<tt>normal label</tt>': the label reached when the called function executes
770a '<tt><a href="#i_ret">ret</a></tt>' instruction.
771
772<li>'<tt>exception label</tt>': the label reached when an exception is thrown.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]773</ol>
774
775<h5>Semantics:</h5>
776
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]777This instruction is designed to operate as a standard '<tt><a
778href="#i_call">call</a></tt>' instruction in most regards. The primary
779difference is that it associates a label with the function invocation that may
780be accessed via the runtime library provided by the execution environment. This
781instruction is used in languages with destructors to ensure that proper cleanup
782is performed in the case of either a <tt>longjmp</tt> or a thrown exception.
783Additionally, this is important for implementation of '<tt>catch</tt>' clauses
784in high-level languages that support them.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]785
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]786<!-- 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]787
788<h5>Example:</h5>
789<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]790 %retval = invoke int %Test(int 15)
791 to label %Continue except label %TestCleanup <i>; {int}:retval set</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]792</pre>
793
794
795
796<!-- ======================================================================= -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]797</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>
798<a name="binaryops">Binary Operations
799</b></font></td></tr></table><ul>
800
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]801Binary operators are used to do most of the computation in a program. They
802require two operands, execute an operation on them, and produce a single value.
803The result value of a binary operator is not neccesarily the same type as its
804operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]805
806There are several different binary operators:<p>
807
808
809<!-- _______________________________________________________________________ -->
810</ul><a name="i_add"><h4><hr size=0>'<tt>add</tt>' Instruction</h4><ul>
811
812<h5>Syntax:</h5>
813<pre>
814 &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
815</pre>
816
817<h5>Overview:</h5>
818The '<tt>add</tt>' instruction returns the sum of its two operands.<p>
819
820<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]821The 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]822
823<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]824
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]825The value produced is the integer or floating point sum of the two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]826
827<h5>Example:</h5>
828<pre>
829 &lt;result&gt; = add int 4, %var <i>; yields {int}:result = 4 + %var</i>
830</pre>
831
832
833<!-- _______________________________________________________________________ -->
834</ul><a name="i_sub"><h4><hr size=0>'<tt>sub</tt>' Instruction</h4><ul>
835
836<h5>Syntax:</h5>
837<pre>
838 &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
839</pre>
840
841<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]842
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]843The '<tt>sub</tt>' instruction returns the difference of its two operands.<p>
844
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]845Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
846instruction present in most other intermediate representations.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]847
848<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]849
850The two arguments to the '<tt>sub</tt>' instruction must be either <a
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]851href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]852values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]853
854<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]855
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]856The value produced is the integer or floating point difference of the two
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]857operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]858
859<h5>Example:</h5>
860<pre>
861 &lt;result&gt; = sub int 4, %var <i>; yields {int}:result = 4 - %var</i>
862 &lt;result&gt; = sub int 0, %val <i>; yields {int}:result = -%var</i>
863</pre>
864
865<!-- _______________________________________________________________________ -->
866</ul><a name="i_mul"><h4><hr size=0>'<tt>mul</tt>' Instruction</h4><ul>
867
868<h5>Syntax:</h5>
869<pre>
870 &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
871</pre>
872
873<h5>Overview:</h5>
874The '<tt>mul</tt>' instruction returns the product of its two operands.<p>
875
876<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]877The 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]878
879<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]880
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]881The value produced is the integer or floating point product of the two
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]882operands.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]883
884There is no signed vs unsigned multiplication. The appropriate action is taken
885based on the type of the operand. <p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]886
887
888<h5>Example:</h5>
889<pre>
890 &lt;result&gt; = mul int 4, %var <i>; yields {int}:result = 4 * %var</i>
891</pre>
892
893
894<!-- _______________________________________________________________________ -->
895</ul><a name="i_div"><h4><hr size=0>'<tt>div</tt>' Instruction</h4><ul>
896
897<h5>Syntax:</h5>
898<pre>
899 &lt;result&gt; = div &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
900</pre>
901
902<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]903
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]904The '<tt>div</tt>' instruction returns the quotient of its two operands.<p>
905
906<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]907
908The two arguments to the '<tt>div</tt>' instruction must be either <a
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]909href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]910values. Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]911
912<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]913
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]914The value produced is the integer or floating point quotient of the two
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]915operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]916
917<h5>Example:</h5>
918<pre>
919 &lt;result&gt; = div int 4, %var <i>; yields {int}:result = 4 / %var</i>
920</pre>
921
922
923<!-- _______________________________________________________________________ -->
924</ul><a name="i_rem"><h4><hr size=0>'<tt>rem</tt>' Instruction</h4><ul>
925
926<h5>Syntax:</h5>
927<pre>
928 &lt;result&gt; = rem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
929</pre>
930
931<h5>Overview:</h5>
932The '<tt>rem</tt>' instruction returns the remainder from the division of its two operands.<p>
933
934<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]935The 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]936
937<h5>Semantics:</h5>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]938
939This returns the <i>remainder</i> of a division (where the result has the same
940sign as the divisor), not the <i>modulus</i> (where the result has the same sign
941as the dividend) of a value. For more information about the difference, see: <a
942href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The Math
943Forum</a>.<p>
944
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]945<h5>Example:</h5>
946<pre>
947 &lt;result&gt; = rem int 4, %var <i>; yields {int}:result = 4 % %var</i>
948</pre>
949
950
951<!-- _______________________________________________________________________ -->
952</ul><a name="i_setcc"><h4><hr size=0>'<tt>set<i>cc</i></tt>' Instructions</h4><ul>
953
954<h5>Syntax:</h5>
955<pre>
956 &lt;result&gt; = seteq &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
957 &lt;result&gt; = setne &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
958 &lt;result&gt; = setlt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
959 &lt;result&gt; = setgt &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
960 &lt;result&gt; = setle &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
961 &lt;result&gt; = setge &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {bool}:result</i>
962</pre>
963
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]964<h5>Overview:</h5> The '<tt>set<i>cc</i></tt>' family of instructions returns a
965boolean value based on a comparison of their two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]966
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]967<h5>Arguments:</h5> The two arguments to the '<tt>set<i>cc</i></tt>'
968instructions must be of <a href="#t_firstclass">first class</a> or <a
969href="#t_pointer">pointer</a> type (it is not possible to compare
970'<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]971values, etc...). Both arguments must have identical types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]972
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]973The '<tt>setlt</tt>', '<tt>setgt</tt>', '<tt>setle</tt>', and '<tt>setge</tt>'
974instructions do not operate on '<tt>bool</tt>' typed arguments.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]975
976<h5>Semantics:</h5>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]977
978The '<tt>seteq</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
979both operands are equal.<br>
980
981The '<tt>setne</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
982both operands are unequal.<br>
983
984The '<tt>setlt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
985the first operand is less than the second operand.<br>
986
987The '<tt>setgt</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
988the first operand is greater than the second operand.<br>
989
990The '<tt>setle</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
991the first operand is less than or equal to the second operand.<br>
992
993The '<tt>setge</tt>' instruction yields a <tt>true</tt> '<tt>bool</tt>' value if
994the first operand is greater than or equal to the second operand.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]995
996<h5>Example:</h5>
997<pre>
998 &lt;result&gt; = seteq int 4, 5 <i>; yields {bool}:result = false</i>
999 &lt;result&gt; = setne float 4, 5 <i>; yields {bool}:result = true</i>
1000 &lt;result&gt; = setlt uint 4, 5 <i>; yields {bool}:result = true</i>
1001 &lt;result&gt; = setgt sbyte 4, 5 <i>; yields {bool}:result = false</i>
1002 &lt;result&gt; = setle sbyte 4, 5 <i>; yields {bool}:result = true</i>
1003 &lt;result&gt; = setge sbyte 4, 5 <i>; yields {bool}:result = false</i>
1004</pre>
1005
1006
1007
1008<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1009</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1010<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]1011<a name="bitwiseops">Bitwise Binary Operations
1012</b></font></td></tr></table><ul>
1013
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1014Bitwise binary operators are used to do various forms of bit-twiddling in a
1015program. They are generally very efficient instructions, and can commonly be
1016strength reduced from other instructions. They require two operands, execute an
1017operation on them, and produce a single value. The resulting value of the
1018bitwise binary operators is always the same type as its first operand.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1019
1020<!-- _______________________________________________________________________ -->
1021</ul><a name="i_and"><h4><hr size=0>'<tt>and</tt>' Instruction</h4><ul>
1022
1023<h5>Syntax:</h5>
1024<pre>
1025 &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1026</pre>
1027
1028<h5>Overview:</h5>
1029The '<tt>and</tt>' instruction returns the bitwise logical and of its two operands.<p>
1030
1031<h5>Arguments:</h5>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1032
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1033The two arguments to the '<tt>and</tt>' instruction must be <a
1034href="#t_integral">integral</a> values. Both arguments must have identical
1035types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1036
1037
1038<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1039
1040The truth table used for the '<tt>and</tt>' instruction is:<p>
1041
Chris Lattnerc98cbbc2002-06-25 18:06:50 +0000[diff] [blame]1042<center><table border=1 cellspacing=0 cellpadding=4>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1043<tr><td>In0</td> <td>In1</td> <td>Out</td></tr>
1044<tr><td>0</td> <td>0</td> <td>0</td></tr>
1045<tr><td>0</td> <td>1</td> <td>0</td></tr>
1046<tr><td>1</td> <td>0</td> <td>0</td></tr>
1047<tr><td>1</td> <td>1</td> <td>1</td></tr>
1048</table></center><p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1049
1050
1051<h5>Example:</h5>
1052<pre>
1053 &lt;result&gt; = and int 4, %var <i>; yields {int}:result = 4 & %var</i>
1054 &lt;result&gt; = and int 15, 40 <i>; yields {int}:result = 8</i>
1055 &lt;result&gt; = and int 4, 8 <i>; yields {int}:result = 0</i>
1056</pre>
1057
1058
1059
1060<!-- _______________________________________________________________________ -->
1061</ul><a name="i_or"><h4><hr size=0>'<tt>or</tt>' Instruction</h4><ul>
1062
1063<h5>Syntax:</h5>
1064<pre>
1065 &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1066</pre>
1067
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1068<h5>Overview:</h5> The '<tt>or</tt>' instruction returns the bitwise logical
1069inclusive or of its two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1070
1071<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1072
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1073The two arguments to the '<tt>or</tt>' instruction must be <a
1074href="#t_integral">integral</a> values. Both arguments must have identical
1075types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1076
1077
1078<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1079
1080The truth table used for the '<tt>or</tt>' instruction is:<p>
1081
Chris Lattnerc98cbbc2002-06-25 18:06:50 +0000[diff] [blame]1082<center><table border=1 cellspacing=0 cellpadding=4>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1083<tr><td>In0</td> <td>In1</td> <td>Out</td></tr>
1084<tr><td>0</td> <td>0</td> <td>0</td></tr>
1085<tr><td>0</td> <td>1</td> <td>1</td></tr>
1086<tr><td>1</td> <td>0</td> <td>1</td></tr>
1087<tr><td>1</td> <td>1</td> <td>1</td></tr>
1088</table></center><p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1089
1090
1091<h5>Example:</h5>
1092<pre>
1093 &lt;result&gt; = or int 4, %var <i>; yields {int}:result = 4 | %var</i>
1094 &lt;result&gt; = or int 15, 40 <i>; yields {int}:result = 47</i>
1095 &lt;result&gt; = or int 4, 8 <i>; yields {int}:result = 12</i>
1096</pre>
1097
1098
1099<!-- _______________________________________________________________________ -->
1100</ul><a name="i_xor"><h4><hr size=0>'<tt>xor</tt>' Instruction</h4><ul>
1101
1102<h5>Syntax:</h5>
1103<pre>
1104 &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt; <i>; yields {ty}:result</i>
1105</pre>
1106
1107<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1108
1109The '<tt>xor</tt>' instruction returns the bitwise logical exclusive or of its
1110two operands.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1111
1112<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1113
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1114The two arguments to the '<tt>xor</tt>' instruction must be <a
1115href="#t_integral">integral</a> values. Both arguments must have identical
1116types.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1117
1118
1119<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1120
1121The truth table used for the '<tt>xor</tt>' instruction is:<p>
1122
Chris Lattnerc98cbbc2002-06-25 18:06:50 +0000[diff] [blame]1123<center><table border=1 cellspacing=0 cellpadding=4>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1124<tr><td>In0</td> <td>In1</td> <td>Out</td></tr>
1125<tr><td>0</td> <td>0</td> <td>0</td></tr>
1126<tr><td>0</td> <td>1</td> <td>1</td></tr>
1127<tr><td>1</td> <td>0</td> <td>1</td></tr>
1128<tr><td>1</td> <td>1</td> <td>0</td></tr>
1129</table></center><p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1130
1131
1132<h5>Example:</h5>
1133<pre>
1134 &lt;result&gt; = xor int 4, %var <i>; yields {int}:result = 4 ^ %var</i>
1135 &lt;result&gt; = xor int 15, 40 <i>; yields {int}:result = 39</i>
1136 &lt;result&gt; = xor int 4, 8 <i>; yields {int}:result = 12</i>
1137</pre>
1138
1139
1140<!-- _______________________________________________________________________ -->
1141</ul><a name="i_shl"><h4><hr size=0>'<tt>shl</tt>' Instruction</h4><ul>
1142
1143<h5>Syntax:</h5>
1144<pre>
1145 &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
1146</pre>
1147
1148<h5>Overview:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1149
1150The '<tt>shl</tt>' instruction returns the first operand shifted to the left a
1151specified number of bits.
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1152
1153<h5>Arguments:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1154
1155The first argument to the '<tt>shl</tt>' instruction must be an <a
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1156href="#t_integer">integer</a> type. The second argument must be an
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1157'<tt>ubyte</tt>' type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1158
1159<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1160
1161The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1162
1163
1164<h5>Example:</h5>
1165<pre>
1166 &lt;result&gt; = shl int 4, ubyte %var <i>; yields {int}:result = 4 << %var</i>
1167 &lt;result&gt; = shl int 4, ubyte 2 <i>; yields {int}:result = 16</i>
1168 &lt;result&gt; = shl int 1, ubyte 10 <i>; yields {int}:result = 1024</i>
1169</pre>
1170
1171
1172<!-- _______________________________________________________________________ -->
1173</ul><a name="i_shr"><h4><hr size=0>'<tt>shr</tt>' Instruction</h4><ul>
1174
1175
1176<h5>Syntax:</h5>
1177<pre>
1178 &lt;result&gt; = shr &lt;ty&gt; &lt;var1&gt;, ubyte &lt;var2&gt; <i>; yields {ty}:result</i>
1179</pre>
1180
1181<h5>Overview:</h5>
1182The '<tt>shr</tt>' instruction returns the first operand shifted to the right a specified number of bits.
1183
1184<h5>Arguments:</h5>
Chris Lattnereaee9e12002-09-03 00:52:52 +0000[diff] [blame]1185The 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]1186
1187<h5>Semantics:</h5>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1188
1189If the first argument is a <a href="#t_signed">signed</a> type, the most
1190significant bit is duplicated in the newly free'd bit positions. If the first
1191argument is unsigned, zero bits shall fill the empty positions.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1192
1193<h5>Example:</h5>
1194<pre>
1195 &lt;result&gt; = shr int 4, ubyte %var <i>; yields {int}:result = 4 >> %var</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame^]1196 &lt;result&gt; = shr uint 4, ubyte 1 <i>; yields {uint}:result = 2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1197 &lt;result&gt; = shr int 4, ubyte 2 <i>; yields {int}:result = 1</i>
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame^]1198 &lt;result&gt; = shr sbyte 4, ubyte 3 <i>; yields {sbyte}:result = 0</i>
1199 &lt;result&gt; = shr sbyte -2, ubyte 1 <i>; yields {sbyte}:result = -1</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1200</pre>
1201
1202
1203
1204
1205
1206<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1207</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1208<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]1209<a name="memoryops">Memory Access Operations
1210</b></font></td></tr></table><ul>
1211
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1212Accessing 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]1213
1214
1215<!-- _______________________________________________________________________ -->
1216</ul><a name="i_malloc"><h4><hr size=0>'<tt>malloc</tt>' Instruction</h4><ul>
1217
1218<h5>Syntax:</h5>
1219<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1220 &lt;result&gt; = malloc &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
1221 &lt;result&gt; = malloc &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1222</pre>
1223
1224<h5>Overview:</h5>
1225The '<tt>malloc</tt>' instruction allocates memory from the system heap and returns a pointer to it.<p>
1226
1227<h5>Arguments:</h5>
1228
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1229The the '<tt>malloc</tt>' instruction allocates
1230<tt>sizeof(&lt;type&gt;)*NumElements</tt> bytes of memory from the operating
1231system, and returns a pointer of the appropriate type to the program. The
1232second form of the instruction is a shorter version of the first instruction
1233that defaults to allocating one element.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1234
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1235'<tt>type</tt>' must be a sized type<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1236
1237<h5>Semantics:</h5>
1238Memory is allocated, a pointer is returned.<p>
1239
1240<h5>Example:</h5>
1241<pre>
1242 %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
1243
1244 %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]1245 %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
1246 %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1247</pre>
1248
1249
1250<!-- _______________________________________________________________________ -->
1251</ul><a name="i_free"><h4><hr size=0>'<tt>free</tt>' Instruction</h4><ul>
1252
1253<h5>Syntax:</h5>
1254<pre>
1255 free &lt;type&gt; &lt;value&gt; <i>; yields {void}</i>
1256</pre>
1257
1258
1259<h5>Overview:</h5>
1260The '<tt>free</tt>' instruction returns memory back to the unused memory heap, to be reallocated in the future.<p>
1261
1262
1263<h5>Arguments:</h5>
1264
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1265'<tt>value</tt>' shall be a pointer value that points to a value that was
1266allocated with the '<tt><a href="#i_malloc">malloc</a></tt>' instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1267
1268
1269<h5>Semantics:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1270
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1271Access 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]1272
1273<h5>Example:</h5>
1274<pre>
1275 %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
1276 free [4 x ubyte]* %array
1277</pre>
1278
1279
1280<!-- _______________________________________________________________________ -->
1281</ul><a name="i_alloca"><h4><hr size=0>'<tt>alloca</tt>' Instruction</h4><ul>
1282
1283<h5>Syntax:</h5>
1284<pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1285 &lt;result&gt; = alloca &lt;type&gt;, uint &lt;NumElements&gt; <i>; yields {type*}:result</i>
1286 &lt;result&gt; = alloca &lt;type&gt; <i>; yields {type*}:result</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1287</pre>
1288
1289<h5>Overview:</h5>
1290
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1291The '<tt>alloca</tt>' instruction allocates memory on the current stack frame of
1292the procedure that is live until the current function returns to its caller.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1293
1294<h5>Arguments:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1295
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1296The the '<tt>alloca</tt>' instruction allocates
1297<tt>sizeof(&lt;type&gt;)*NumElements</tt> bytes of memory on the runtime stack,
1298returning a pointer of the appropriate type to the program. The second form of
1299the instruction is a shorter version of the first that defaults to allocating
1300one element.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1301
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1302'<tt>type</tt>' may be any sized type.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1303
1304<h5>Semantics:</h5>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1305
1306Memory is allocated, a pointer is returned. '<tt>alloca</tt>'d memory is
1307automatically released when the function returns. The '<tt>alloca</tt>'
1308instruction is commonly used to represent automatic variables that must have an
1309address available, as well as spilled variables.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1310
1311<h5>Example:</h5>
1312<pre>
1313 %ptr = alloca int <i>; yields {int*}:ptr</i>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1314 %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1315</pre>
1316
1317
1318<!-- _______________________________________________________________________ -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1319</ul><a name="i_load"><h4><hr size=0>'<tt>load</tt>' Instruction</h4><ul>
1320
1321<h5>Syntax:</h5>
1322<pre>
1323 &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;
1324</pre>
1325
1326<h5>Overview:</h5>
1327The '<tt>load</tt>' instruction is used to read from memory.<p>
1328
1329<h5>Arguments:</h5>
1330
1331The 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>
1332
1333<h5>Semantics:</h5>
1334
1335The location of memory pointed to is loaded.
1336
1337<h5>Examples:</h5>
1338<pre>
1339 %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1340 <a href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
1341 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1342</pre>
1343
1344
1345
1346
1347<!-- _______________________________________________________________________ -->
1348</ul><a name="i_store"><h4><hr size=0>'<tt>store</tt>' Instruction</h4><ul>
1349
1350<h5>Syntax:</h5>
1351<pre>
1352 store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt; <i>; yields {void}</i>
1353</pre>
1354
1355<h5>Overview:</h5>
1356The '<tt>store</tt>' instruction is used to write to memory.<p>
1357
1358<h5>Arguments:</h5>
1359
1360There are two arguments to the '<tt>store</tt>' instruction: a value to store
1361and an address to store it into. The type of the '<tt>&lt;pointer&gt;</tt>'
1362operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
1363operand.<p>
1364
1365<h5>Semantics:</h5> The contents of memory are updated to contain
1366'<tt>&lt;value&gt;</tt>' at the location specified by the
1367'<tt>&lt;pointer&gt;</tt>' operand.<p>
1368
1369<h5>Example:</h5>
1370<pre>
1371 %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
1372 <a href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
1373 %val = load int* %ptr <i>; yields {int}:val = int 3</i>
1374</pre>
1375
1376
1377
1378
1379<!-- _______________________________________________________________________ -->
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1380</ul><a name="i_getelementptr"><h4><hr size=0>'<tt>getelementptr</tt>' Instruction</h4><ul>
1381
1382<h5>Syntax:</h5>
1383<pre>
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1384 &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, long &lt;aidx&gt;|, ubyte &lt;sidx&gt;}*
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1385</pre>
1386
1387<h5>Overview:</h5>
1388
1389The '<tt>getelementptr</tt>' instruction is used to get the address of a
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1390subelement of an aggregate data structure.<p>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1391
1392<h5>Arguments:</h5>
1393
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1394This instruction takes a list of <tt>long</tt> values and <tt>ubyte</tt>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1395constants that indicate what form of addressing to perform. The actual types of
1396the arguments provided depend on the type of the first pointer argument. The
1397'<tt>getelementptr</tt>' instruction is used to index down through the type
1398levels of a structure.<p>
1399
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1400For example, lets consider a C code fragment and how it gets compiled to
1401LLVM:<p>
1402
1403<pre>
1404struct RT {
1405 char A;
1406 int B[10][20];
1407 char C;
1408};
1409struct ST {
1410 int X;
1411 double Y;
1412 struct RT Z;
1413};
1414
1415int *foo(struct ST *s) {
1416 return &amp;s[1].Z.B[5][13];
1417}
1418</pre>
1419
1420The LLVM code generated by the GCC frontend is:
1421
1422<pre>
1423%RT = type { sbyte, [10 x [20 x int]], sbyte }
1424%ST = type { int, double, %RT }
1425
1426int* "foo"(%ST* %s) {
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1427 %reg = getelementptr %ST* %s, long 1, ubyte 2, ubyte 1, long 5, long 13
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1428 ret int* %reg
1429}
1430</pre>
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1431
1432<h5>Semantics:</h5>
1433
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1434The index types specified for the '<tt>getelementptr</tt>' instruction depend on
1435the pointer type that is being index into. <a href="t_pointer">Pointer</a> and
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1436<a href="t_array">array</a> types require '<tt>long</tt>' values, and <a
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1437href="t_struct">structure</a> types require '<tt>ubyte</tt>'
1438<b>constants</b>.<p>
1439
1440In the example above, the first index is indexing into the '<tt>%ST*</tt>' type,
1441which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT }</tt>'
1442type, a structure. The second index indexes into the third element of the
1443structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]], sbyte
1444}</tt>' type, another structure. The third index indexes into the second
1445element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
1446array. The two dimensions of the array are subscripted into, yielding an
1447'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction return a pointer
1448to this element, thus yielding a '<tt>int*</tt>' type.<p>
1449
1450Note that it is perfectly legal to index partially through a structure,
1451returning a pointer to an inner element. Because of this, the LLVM code for the
1452given testcase is equivalent to:<p>
1453
1454<pre>
1455int* "foo"(%ST* %s) {
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1456 %t1 = getelementptr %ST* %s , long 1 <i>; yields %ST*:%t1</i>
1457 %t2 = getelementptr %ST* %t1, long 0, ubyte 2 <i>; yields %RT*:%t2</i>
1458 %t3 = getelementptr %RT* %t2, long 0, ubyte 1 <i>; yields [10 x [20 x int]]*:%t3</i>
1459 %t4 = getelementptr [10 x [20 x int]]* %t3, long 0, long 5 <i>; yields [20 x int]*:%t4</i>
1460 %t5 = getelementptr [20 x int]* %t4, long 0, long 13 <i>; yields int*:%t5</i>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1461 ret int* %t5
1462}
1463</pre>
1464
1465
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1466
1467<h5>Example:</h5>
1468<pre>
Chris Lattnerf31860b2002-08-19 21:14:38 +0000[diff] [blame]1469 <i>; yields [12 x ubyte]*:aptr</i>
Chris Lattner3dfa10b2002-12-13 06:01:21 +0000[diff] [blame]1470 %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, ubyte 1
Chris Lattner7faa8832002-04-14 06:13:44 +0000[diff] [blame]1471</pre>
1472
1473
1474
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1475<!-- ======================================================================= -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1476</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1477<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]1478<a name="otherops">Other Operations
1479</b></font></td></tr></table><ul>
1480
1481The instructions in this catagory are the "miscellaneous" functions, that defy better classification.<p>
1482
1483
1484<!-- _______________________________________________________________________ -->
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1485</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]1486
1487<h5>Syntax:</h5>
1488<pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1489 &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1490</pre>
1491
1492<h5>Overview:</h5>
1493
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1494The '<tt>phi</tt>' instruction is used to implement the &phi; node in the SSA
1495graph representing the function.<p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1496
1497<h5>Arguments:</h5>
1498
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1499The type of the incoming values are specified with the first type field. After
1500this, the '<tt>phi</tt>' instruction takes a list of pairs as arguments, with
1501one pair for each predecessor basic block of the current block.<p>
1502
1503There must be no non-phi instructions between the start of a basic block and the
1504PHI instructions: i.e. PHI instructions must be first in a basic block.<p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1505
1506<h5>Semantics:</h5>
1507
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1508At runtime, the '<tt>phi</tt>' instruction logically takes on the value
1509specified by the parameter, depending on which basic block we came from in the
1510last <a href="#terminators">terminator</a> instruction.<p>
1511
1512<h5>Example:</h5>
1513
1514<pre>
1515Loop: ; Infinite loop that counts from 0 on up...
1516 %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
1517 %nextindvar = add uint %indvar, 1
1518 br label %Loop
1519</pre>
1520
1521
1522<!-- _______________________________________________________________________ -->
1523</ul><a name="i_cast"><h4><hr size=0>'<tt>cast .. to</tt>' Instruction</h4><ul>
1524
1525<h5>Syntax:</h5>
1526<pre>
1527 &lt;result&gt; = cast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt; <i>; yields ty2</i>
1528</pre>
1529
1530<h5>Overview:</h5>
1531
1532The '<tt>cast</tt>' instruction is used as the primitive means to convert
1533integers to floating point, change data type sizes, and break type safety (by
1534casting pointers).<p>
1535
1536<h5>Arguments:</h5>
1537
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1538The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1539class value, and a type to cast it to, which must also be a first class type.<p>
1540
1541<h5>Semantics:</h5>
1542
1543This instruction follows the C rules for explicit casts when determining how the
1544data being cast must change to fit in its new container.<p>
1545
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1546When casting to bool, any value that would be considered true in the context of
1547a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
1548all else are '<tt>false</tt>'.<p>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1549
Chris Lattnerf8856bc2002-08-13 20:52:09 +0000[diff] [blame]1550When extending an integral value from a type of one signness to another (for
1551example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
1552<b>source</b> value is signed, and zero-extended if the source value is
Chris Lattner2b4dcbb2002-08-15 19:36:05 +0000[diff] [blame]1553unsigned. <tt>bool</tt> values are always zero extended into either zero or
1554one.<p>
Chris Lattnerf8856bc2002-08-13 20:52:09 +0000[diff] [blame]1555
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1556<h5>Example:</h5>
1557<pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1558 %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
Chris Lattner7bae3952002-06-25 18:03:17 +0000[diff] [blame]1559 %Y = cast int 123 to bool <i>; yields bool:true</i>
Chris Lattner33ba0d92001-07-09 00:26:23 +0000[diff] [blame]1560</pre>
1561
1562
1563
1564<!-- _______________________________________________________________________ -->
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1565</ul><a name="i_call"><h4><hr size=0>'<tt>call</tt>' Instruction</h4><ul>
1566
1567<h5>Syntax:</h5>
1568<pre>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1569 &lt;result&gt; = call &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1570</pre>
1571
1572<h5>Overview:</h5>
1573
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1574The '<tt>call</tt>' instruction represents a simple function call.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1575
1576<h5>Arguments:</h5>
1577
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1578This instruction requires several arguments:<p>
1579<ol>
1580
1581<li>'<tt>ty</tt>': shall be the signature of the pointer to function value being
1582invoked. The argument types must match the types implied by this signature.<p>
1583
1584<li>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to be
1585invoked. In most cases, this is a direct function invocation, but indirect
Misha Brukmane6fe6712002-09-18 02:35:14 +0000[diff] [blame]1586<tt>call</tt>s are just as possible, calling an arbitrary pointer to function
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1587values.<p>
1588
1589<li>'<tt>function args</tt>': argument list whose types match the function
1590signature argument types. If the function signature indicates the function
1591accepts a variable number of arguments, the extra arguments can be specified.
1592</ol>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1593
1594<h5>Semantics:</h5>
1595
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1596The '<tt>call</tt>' instruction is used to cause control flow to transfer to a
1597specified function, with its incoming arguments bound to the specified values.
1598Upon a '<tt><a href="#i_ret">ret</a></tt>' instruction in the called function,
1599control flow continues with the instruction after the function call, and the
1600return value of the function is bound to the result argument. This is a simpler
1601case of the <a href="#i_invoke">invoke</a> instruction.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1602
1603<h5>Example:</h5>
1604<pre>
1605 %retval = call int %test(int %argc)
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1606 call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);
1607
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1608</pre>
1609
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1610<!-- _______________________________________________________________________ -->
1611</ul><a name="i_va_arg"><h4><hr size=0>'<tt>va_arg</tt>' Instruction</h4><ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1612
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1613<h5>Syntax:</h5>
1614<pre>
1615 &lt;result&gt; = va_arg &lt;va_list&gt;* &lt;arglist&gt;, &lt;retty&gt;
1616</pre>
1617
1618<h5>Overview:</h5>
1619
1620The '<tt>va_arg</tt>' instruction is used to access arguments passed through the
1621"variable argument" area of a function call. It corresponds directly to the
1622<tt>va_arg</tt> macro in C.<p>
1623
1624<h5>Arguments:</h5>
1625
1626This instruction takes a pointer to a <tt>valist</tt> value to read a new
1627argument from. The return type of the instruction is defined by the second
1628argument, a type.<p>
1629
1630<h5>Semantics:</h5>
1631
1632The '<tt>va_arg</tt>' instruction works just like the <tt>va_arg</tt> macro
1633available in C. In a target-dependent way, it reads the argument indicated by
1634the value the arglist points to, updates the arglist, then returns a value of
1635the specified type. This instruction should be used in conjunction with the
1636variable argument handling <a href="#int_varargs">Intrinsic Functions</a>.<p>
1637
1638It is legal for this instruction to be called in a function which does not take
1639a variable number of arguments, for example, the <tt>vfprintf</tt> function.<p>
1640
1641<tt>va_arg</tt> is an LLVM instruction instead of an <a
1642href="#intrinsics">intrinsic function</a> because the return type depends on an
1643argument.<p>
1644
1645<h5>Example:</h5>
1646
1647See the <a href="#int_varargs">variable argument processing</a> section.<p>
1648
1649<!-- *********************************************************************** -->
Chris Lattner2b7d3202002-05-06 03:03:22 +0000[diff] [blame]1650</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
1651<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1652<a name="intrinsics">Intrinsic Functions
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1653</b></font></td></tr></table><ul>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1654<!-- *********************************************************************** -->
1655
1656LLVM supports the notion of an "intrinsic function". These functions have well
1657known names and semantics, and are required to follow certain restrictions.
1658Overall, these instructions represent an extension mechanism for the LLVM
1659language that does not require changing all of the transformations in LLVM to
1660add to the language (or the bytecode reader/writer, the parser, etc...).<p>
1661
1662Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix, this
1663prefix is reserved in LLVM for intrinsic names, thus functions may not be named
1664this. Intrinsic functions must always be external functions: you cannot define
1665the body of intrinsic functions. Intrinsic functions may only be used in call
1666or invoke instructions: it is illegal to take the address of an intrinsic
1667function. Additionally, because intrinsic functions are part of the LLVM
1668language, it is required that they all be documented here if any are added.<p>
1669
1670Unless an intrinsic function is target-specific, there must be a lowering pass
1671to eliminate the intrinsic or all backends must support the intrinsic
1672function.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1673
1674
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1675<!-- ======================================================================= -->
1676</ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
1677<tr><td>&nbsp;</td><td width="100%">&nbsp; <font color="#EEEEFF" face="Georgia,Palatino"><b>
1678<a name="int_varargs">Variable Argument Handling Intrinsics
1679</b></font></td></tr></table><ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1680
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1681Variable argument support is defined in LLVM with the <a
1682href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three intrinsic
1683functions. These function correspond almost directly to the similarly named
1684macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1685
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1686All of these functions operate on arguments that use a target-specific type
1687"<tt>va_list</tt>". The LLVM assembly language reference manual does not define
1688what this type is, so all transformations should be prepared to handle
1689intrinsics with any type used.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1690
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1691This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a> instruction
1692and the variable argument handling intrinsic functions are used.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1693
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1694<pre>
1695int %test(int %X, ...) {
1696 ; Allocate two va_list items. On this target, va_list is of type sbyte*
1697 %ap = alloca sbyte*
1698 %aq = alloca sbyte*
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1699
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1700 ; Initialize variable argument processing
Chris Lattnera1a20972003-05-08 15:55:44 +0000[diff] [blame]1701 call void (sbyte**)* %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1702
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1703 ; Read a single integer argument
1704 %tmp = <a href="#i_va_arg">va_arg</a> sbyte** %ap, int
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1705
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1706 ; Demonstrate usage of llvm.va_copy and llvm_va_end
1707 %apv = load sbyte** %ap
1708 call void %<a href="#i_va_copy">llvm.va_copy</a>(sbyte** %aq, sbyte* %apv)
1709 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1710
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1711 ; Stop processing of arguments.
1712 call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
1713 ret int %tmp
1714}
1715</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1716
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1717<!-- _______________________________________________________________________ -->
1718</ul><a name="i_va_start"><h4><hr size=0>'<tt>llvm.va_start</tt>' Intrinsic</h4><ul>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1719
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1720<h5>Syntax:</h5>
1721<pre>
Chris Lattnera1a20972003-05-08 15:55:44 +0000[diff] [blame]1722 call void (va_list*)* %llvm.va_start(&lt;va_list&gt;* &lt;arglist&gt;)
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1723</pre>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1724
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1725<h5>Overview:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1726
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1727The '<tt>llvm.va_start</tt>' intrinsic initializes <tt>*&lt;arglist&gt;</tt> for
1728subsequent use by <tt><a href="#i_va_arg">va_arg</a></tt> and <tt><a
1729href="#i_va_end">llvm.va_end</a></tt>, and must be called before either are
1730invoked.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1731
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1732<h5>Arguments:</h5>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1733
Chris Lattnera1a20972003-05-08 15:55:44 +0000[diff] [blame]1734The argument is a pointer to a <tt>va_list</tt> element to initialize.<p>
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1735
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1736<h5>Semantics:</h5>
1737
1738The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
1739macro available in C. In a target-dependent way, it initializes the
Chris Lattnera1a20972003-05-08 15:55:44 +0000[diff] [blame]1740<tt>va_list</tt> element the argument points to, so that the next call to
1741<tt>va_arg</tt> will produce the first variable argument passed to the function.
1742Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
1743last argument of the function, the compiler can figure that out.<p>
Chris Lattnerd9ad5b32003-05-08 04:57:36 +0000[diff] [blame]1744
1745
1746<!-- _______________________________________________________________________ -->
1747</ul><a name="i_va_end"><h4><hr size=0>'<tt>llvm.va_end</tt>' Intrinsic</h4><ul>
1748
1749<h5>Syntax:</h5>
1750<pre>
1751 call void (va_list*)* %llvm.va_end(&lt;va_list&gt;* &lt;arglist&gt;)
1752</pre>
1753
1754<h5>Overview:</h5>
1755
1756The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt> which
1757has been initialized previously with <tt><a
1758href="#i_va_begin">llvm.va_begin</a></tt>.<p>
1759
1760<h5>Arguments:</h5>
1761
1762The argument is a pointer to a <tt>va_list</tt> element to destroy.<p>
1763
1764<h5>Semantics:</h5>
1765
1766The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt> macro
1767available in C. In a target-dependent way, it destroys the <tt>va_list</tt>
1768that the argument points to. Calls to <a
1769href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
1770href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly with calls
1771to <tt>llvm.va_end</tt>.<p>
1772
1773
1774
1775<!-- _______________________________________________________________________ -->
1776</ul><a name="i_va_copy"><h4><hr size=0>'<tt>llvm.va_copy</tt>' Intrinsic</h4><ul>
1777
1778<h5>Syntax:</h5>
1779<pre>
1780 call void (va_list*, va_list)* %va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
1781 &lt;va_list&gt; &lt;srcarglist&gt;)
1782</pre>
1783
1784<h5>Overview:</h5>
1785
1786The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position from
1787the source argument list to the destination argument list.<p>
1788
1789<h5>Arguments:</h5>
1790
1791The first argument is a pointer to a <tt>va_list</tt> element to initialize.
1792The second argument is a <tt>va_list</tt> element to copy from.<p>
1793
1794
1795<h5>Semantics:</h5>
1796
1797The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
1798available in C. In a target-dependent way, it copies the source
1799<tt>va_list</tt> element into the destination list. This intrinsic is necessary
1800because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
1801arbitrarily complex and require memory allocation, for example.<p>
Chris Lattner6536cfe2002-05-06 22:08:29 +0000[diff] [blame]1802
1803
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1804<!-- *********************************************************************** -->
1805</ul>
1806<!-- *********************************************************************** -->
1807
1808
1809<hr>
1810<font size=-1>
1811<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
1812<!-- Created: Tue Jan 23 15:19:28 CST 2001 -->
1813<!-- hhmts start -->
Chris Lattner8c6bb902003-06-18 21:30:51 +0000[diff] [blame^]1814Last modified: Wed Jun 18 16:29:55 CDT 2003
Chris Lattner00950542001-06-06 20:29:01 +0000[diff] [blame]1815<!-- hhmts end -->
1816</font>
1817</body></html>