blob: c6c3a81ab50fecf8eb5ce104a18d622c90459e81 [file] [log] [blame]
Reid Spencer85baf762004-08-17 09:38:50 +00001<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
2<html>
3<head>
4 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
5 <title>The LLVM Lexicon</title>
6 <link rel="stylesheet" href="llvm.css" type="text/css">
Reid Spencer85baf762004-08-17 09:38:50 +00007 <meta name="author" content="Various">
8 <meta name="description"
9 content="A glossary of terms used with the LLVM project.">
10</head>
11<body>
NAKAMURA Takumi05d02652011-04-18 23:59:50 +000012<h1>The LLVM Lexicon</h1>
Reid Spencer85baf762004-08-17 09:38:50 +000013<p class="doc_warning">NOTE: This document is a work in progress!</p>
14<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +000015<h2>Table Of Contents</h2>
Reid Spencer85baf762004-08-17 09:38:50 +000016<!-- *********************************************************************** -->
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +000017<div>
Reid Spencer85baf762004-08-17 09:38:50 +000018 <table>
Reid Spencerd3f876c2004-11-01 08:19:36 +000019 <tr><th colspan="8"><b>- <a href="#A">A</a> -</b></th></tr>
Reid Spencer85baf762004-08-17 09:38:50 +000020 <tr>
21 <td><a href="#ADCE">ADCE</a></td>
Reid Spencer85baf762004-08-17 09:38:50 +000022 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000023 <tr><th colspan="8"><b>- <a href="#B">B</a> -</b></th></tr>
Reid Spencerce6be332004-08-24 18:34:10 +000024 <tr>
25 <td><a href="#BURS">BURS</a></td>
Reid Spencerce6be332004-08-24 18:34:10 +000026 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000027 <tr><th colspan="8"><b>- <a href="#C">C</a> -</b></th></tr>
Reid Spencera07e0b52004-10-30 21:40:28 +000028 <tr>
29 <td><a href="#CSE">CSE</a></td>
Reid Spencera07e0b52004-10-30 21:40:28 +000030 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000031 <tr><th colspan="8"><b>- <a href="#D">D</a> -</b></th></tr>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000032 <tr>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000033 <td><a href="#DAG">DAG</a></td>
34 <td><a href="#Derived_Pointer">Derived Pointer</a></td>
Misha Brukman9a4c9042004-09-05 03:00:20 +000035 <td><a href="#DSA">DSA</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000036 <td><a href="#DSE">DSE</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000037 </tr>
Bill Wendlingab15bf72011-09-27 18:44:01 +000038 <tr><th colspan="8"><b>- <a href="#F">F</a> -</b></th></tr>
39 <tr>
40 <td><a href="#FCA">FCA</a></td>
41 </tr>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000042 <tr><th colspan="8"><b>- <a href="#G">G</a> -</b></th></tr>
Dan Gohmanf0032762008-11-24 17:18:39 +000043 <tr>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000044 <td><a href="#GC">GC</a></td>
45 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000046 <tr><th colspan="8"><b>- <a href="#I">I</a> -</b></th></tr>
Reid Spencera07e0b52004-10-30 21:40:28 +000047 <tr>
48 <td><a href="#IPA">IPA</a></td>
49 <td><a href="#IPO">IPO</a></td>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000050 <td><a href="#ISel">ISel</a></td>
Reid Spencera07e0b52004-10-30 21:40:28 +000051 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000052 <tr><th colspan="8"><b>- <a href="#L">L</a> -</b></th></tr>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000053 <tr>
Owen Andersona6fc5012006-10-18 05:50:12 +000054 <td><a href="#LCSSA">LCSSA</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000055 <td><a href="#LICM">LICM</a></td>
Misha Brukman183cfc22004-08-24 04:13:17 +000056 <td><a href="#Load-VN">Load-VN</a></td>
Nick Lewycky00759c12010-04-05 05:48:47 +000057 <td><a href="#LTO">LTO</a></td>
58 </tr>
59 <tr><th colspan="8"><b>- <a href="#M">M</a> -</b></th></tr>
60 <tr>
61 <td><a href="#MC">MC</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000062 </tr>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000063 <tr><th colspan="8"><b>- <a href="#O">O</a> -</b></th></tr>
64 <tr>
65 <td><a href="#Object_Pointer">Object Pointer</a></td>
66 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000067 <tr><th colspan="8"><b>- <a href="#P">P</a> -</b></th></tr>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000068 <tr>
69 <td><a href="#PRE">PRE</a></td>
Chris Lattnerdbb85852005-05-13 20:18:49 +000070 </tr>
71 <tr><th colspan="8"><b>- <a href="#R">R</a> -</b></th></tr>
72 <tr>
Dan Gohmanc4479a72008-11-07 20:29:17 +000073 <td><a href="#RAUW">RAUW</a></td>
Chris Lattnerdbb85852005-05-13 20:18:49 +000074 <td><a href="#Reassociation">Reassociation</a></td>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000075 <td><a href="#Root">Root</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000076 </tr>
Reid Spencerd3f876c2004-11-01 08:19:36 +000077 <tr><th colspan="8"><b>- <a href="#S">S</a> -</b></th></tr>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000078 <tr>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000079 <td><a href="#Safe_Point">Safe Point</a></td>
Chris Lattner59f7f212005-11-29 01:34:50 +000080 <td><a href="#SCC">SCC</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000081 <td><a href="#SCCP">SCCP</a></td>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000082 <td><a href="#SDISel">SDISel</a></td>
Chris Lattnered51a0f2006-02-08 16:59:49 +000083 <td><a href="#SRoA">SRoA</a></td>
Gordon Henriksen326e24f2007-09-27 19:31:36 +000084 <td><a href="#Stack_Map">Stack Map</a></td>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000085 </tr>
Reid Spencer85baf762004-08-17 09:38:50 +000086 </table>
87</div>
88
89<!-- *********************************************************************** -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +000090<h2>Definitions</h2>
Reid Spencer85baf762004-08-17 09:38:50 +000091<!-- *********************************************************************** -->
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +000092<div>
Reid Spencer85baf762004-08-17 09:38:50 +000093<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +000094<h3><a name="A">- A -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +000095<div>
Reid Spencer85baf762004-08-17 09:38:50 +000096 <dl>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +000097 <dt><a name="ADCE"><b>ADCE</b></a></dt>
98 <dd>Aggressive Dead Code Elimination</dd>
Reid Spencer85baf762004-08-17 09:38:50 +000099 </dl>
100</div>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000101<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000102<h3><a name="B">- B -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000103<div>
Reid Spencerce6be332004-08-24 18:34:10 +0000104 <dl>
105 <dt><a name="BURS"><b>BURS</b></a></dt>
Bill Wendling7c6d4102008-07-22 06:46:17 +0000106 <dd>Bottom Up Rewriting System&mdash;A method of instruction selection for
Chris Lattnerc4985ba2004-08-24 18:53:39 +0000107 code generation. An example is the <a
108href="http://www.program-transformation.org/Transform/BURG">BURG</a> tool.</dd>
Reid Spencerce6be332004-08-24 18:34:10 +0000109 </dl>
110</div>
111<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000112<h3><a name="C">- C -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000113<div>
Reid Spencera07e0b52004-10-30 21:40:28 +0000114 <dl>
115 <dt><a name="CSE"><b>CSE</b></a></dt>
116 <dd>Common Subexpression Elimination. An optimization that removes common
117 subexpression compuation. For example <tt>(a+b)*(a+b)</tt> has two
118 subexpressions that are the same: <tt>(a+b)</tt>. This optimization would
119 perform the addition only once and then perform the multiply (but only if
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000120 it's compulationally correct/safe).
Reid Spencera07e0b52004-10-30 21:40:28 +0000121 </dl>
122</div>
123<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000124<h3><a name="D">- D -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000125<div>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000126 <dl>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000127 <dt><a name="DAG"><b>DAG</b></a></dt>
128 <dd>Directed Acyclic Graph</dd>
129 <dt><a name="Derived_Pointer"><b>Derived Pointer</b></a></dt>
130 <dd>A pointer to the interior of an object, such that a garbage collector
131 is unable to use the pointer for reachability analysis. While a derived
132 pointer is live, the corresponding object pointer must be kept in a root,
133 otherwise the collector might free the referenced object. With copying
134 collectors, derived pointers pose an additional hazard that they may be
135 invalidated at any <a href="Safe_Point">safe point</a>. This term is used in
136 opposition to <a href="#Object_Pointer">object pointer</a>.</dd>
Misha Brukman9a4c9042004-09-05 03:00:20 +0000137 <dt><a name="DSA"><b>DSA</b></a></dt>
Misha Brukman100bd712004-09-05 03:57:23 +0000138 <dd>Data Structure Analysis</dd>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000139 <dt><a name="DSE"><b>DSE</b></a></dt>
140 <dd>Dead Store Elimination</dd>
141 </dl>
142</div>
143<!-- _______________________________________________________________________ -->
Bill Wendlingab15bf72011-09-27 18:44:01 +0000144<h3><a name="F">- F -</a></h3>
145<div>
146 <dl>
147 <dt><a name="FCA"><b>FCA</b></a></dt>
148 <dd>First Class Aggregate</dd>
149 </dl>
150</div>
151<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000152<h3><a name="G">- G -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000153<div>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000154 <dl>
155 <dt><a name="GC"><b>GC</b></a></dt>
156 <dd>Garbage Collection. The practice of using reachability analysis instead
157 of explicit memory management to reclaim unused memory.</dd>
158 </dl>
159</div>
160<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000161<h3><a name="H">- H -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000162<div>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000163 <dl>
164 <dt><a name="Heap"><b>Heap</b></a></dt>
165 <dd>In garbage collection, the region of memory which is managed using
166 reachability analysis.</dd>
167 </dl>
168</div>
169<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000170<h3><a name="I">- I -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000171<div>
Reid Spencera07e0b52004-10-30 21:40:28 +0000172 <dl>
173 <dt><a name="IPA"><b>IPA</b></a></dt>
174 <dd>Inter-Procedural Analysis. Refers to any variety of code analysis that
175 occurs between procedures, functions or compilation units (modules).</dd>
176 <dt><a name="IPO"><b>IPO</b></a></dt>
177 <dd>Inter-Procedural Optimization. Refers to any variety of code
178 optimization that occurs between procedures, functions or compilation units
179 (modules).</dd>
Torok Edwin2b9cbf12008-10-28 16:54:34 +0000180 <dt><a name="ISel"><b>ISel</b></a></dt>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000181 <dd>Instruction Selection.</dd>
Reid Spencera07e0b52004-10-30 21:40:28 +0000182 </dl>
183</div>
184<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000185<h3><a name="L">- L -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000186<div>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000187 <dl>
Nick Lewycky00759c12010-04-05 05:48:47 +0000188 <dt><a name="LCSSA"><b>LCSSA</b></a></dt>
189 <dd>Loop-Closed Static Single Assignment Form</dd>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000190 <dt><a name="LICM"><b>LICM</b></a></dt>
191 <dd>Loop Invariant Code Motion</dd>
Misha Brukman183cfc22004-08-24 04:13:17 +0000192 <dt><a name="Load-VN"><b>Load-VN</b></a></dt>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000193 <dd>Load Value Numbering</dd>
Nick Lewycky00759c12010-04-05 05:48:47 +0000194 <dt><a name="LTO"><b>LTO</b></a></dt>
195 <dd>Link-Time Optimization</dd>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000196 </dl>
197</div>
Nick Lewycky00759c12010-04-05 05:48:47 +0000198<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000199<h3><a name="M">- M -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000200<div>
Nick Lewycky00759c12010-04-05 05:48:47 +0000201 <dl>
202 <dt><a name="MC"><b>MC</b></a></dt>
203 <dd>Machine Code</dd>
204 </dl>
205</div>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000206<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000207<h3><a name="O">- O -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000208<div>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000209 <dl>
210 <dt><a name="Object_Pointer"><b>Object Pointer</b></a></dt>
211 <dd>A pointer to an object such that the garbage collector is able to trace
212 references contained within the object. This term is used in opposition to
213 <a href="#Derived_Pointer">derived pointer</a>.</dd>
214 </dl>
215</div>
216
217<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000218<h3><a name="P">- P -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000219<div>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000220 <dl>
221 <dt><a name="PRE"><b>PRE</b></a></dt>
222 <dd>Partial Redundancy Elimination</dd>
223 </dl>
224</div>
Chris Lattnerdbb85852005-05-13 20:18:49 +0000225
226<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000227<h3><a name="R">- R -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000228<div>
Chris Lattnerdbb85852005-05-13 20:18:49 +0000229 <dl>
Dan Gohmanc4479a72008-11-07 20:29:17 +0000230 <dt><a name="RAUW"><b>RAUW</b></a></dt> <dd>An abbreviation for Replace
231 All Uses With. The functions User::replaceUsesOfWith(),
232 Value::replaceAllUsesWith(), and Constant::replaceUsesOfWithOnConstant()
233 implement the replacement of one Value with another by iterating over its
234 def/use chain and fixing up all of the pointers to point to the new value.
235 See also <a href="ProgrammersManual.html#iterate_chains">def/use chains</a>.
236 </dd>
Chris Lattnerdbb85852005-05-13 20:18:49 +0000237 <dt><a name="Reassociation"><b>Reassociation</b></a></dt> <dd>Rearranging
238 associative expressions to promote better redundancy elimination and other
239 optimization. For example, changing (A+B-A) into (B+A-A), permitting it to
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000240 be optimized into (B+0) then (B).</dd>
241 <dt><a name="Root"><b>Root</b></a></dt> <dd>In garbage collection, a
242 pointer variable lying outside of the <a href="#Heap">heap</a> from which
243 the collector begins its reachability analysis. In the context of code
Misha Brukman3c8da592008-12-14 08:01:51 +0000244 generation, "root" almost always refers to a "stack root" -- a local or
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000245 temporary variable within an executing function.</dd>
Chris Lattnerdbb85852005-05-13 20:18:49 +0000246 </dl>
247</div>
248
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000249<!-- _______________________________________________________________________ -->
NAKAMURA Takumi05d02652011-04-18 23:59:50 +0000250<h3><a name="S">- S -</a></h3>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000251<div>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000252 <dl>
Torok Edwin2b9cbf12008-10-28 16:54:34 +0000253 <dt><a name="Safe_Point"><b>Safe Point</b></a></dt>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000254 <dd>In garbage collection, it is necessary to identify <a href="#Root">stack
255 roots</a> so that reachability analysis may proceed. It may be infeasible to
256 provide this information for every instruction, so instead the information
257 may is calculated only at designated safe points. With a copying collector,
258 <a href="#Derived_Pointers">derived pointers</a> must not be retained across
259 safe points and <a href="#Object_Pointers">object pointers</a> must be
260 reloaded from stack roots.</dd>
261 <dt><a name="SDISel"><b>SDISel</b></a></dt>
262 <dd>Selection DAG Instruction Selection.</dd>
Chris Lattner59f7f212005-11-29 01:34:50 +0000263 <dt><a name="SCC"><b>SCC</b></a></dt>
264 <dd>Strongly Connected Component</dd>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000265 <dt><a name="SCCP"><b>SCCP</b></a></dt>
Chris Lattner59f7f212005-11-29 01:34:50 +0000266 <dd>Sparse Conditional Constant Propagation</dd>
Chris Lattnered51a0f2006-02-08 16:59:49 +0000267 <dt><a name="SRoA"><b>SRoA</b></a></dt>
268 <dd>Scalar Replacement of Aggregates</dd>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000269 <dt><a name="SSA"><b>SSA</b></a></dt>
270 <dd>Static Single Assignment</dd>
Gordon Henriksen326e24f2007-09-27 19:31:36 +0000271 <dt><a name="Stack_Map"><b>Stack Map</b></a></dt>
272 <dd>In garbage collection, metadata emitted by the code generator which
273 identifies <a href="#Root">roots</a> within the stack frame of an executing
274 function.</dd>
Misha Brukmanec8fe3c2004-08-24 01:57:02 +0000275 </dl>
276</div>
NAKAMURA Takumif5af6ad2011-04-23 00:30:22 +0000277
Eli Bendersky30c90c92012-01-05 08:18:41 +0000278</div>
Reid Spencer85baf762004-08-17 09:38:50 +0000279<!-- *********************************************************************** -->
280<hr>
281<address> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000282 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a><a
Reid Spencer85baf762004-08-17 09:38:50 +0000283 href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000284 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a><a
Reid Spencer05fe4b02006-03-14 05:39:39 +0000285 href="http://llvm.org/">The LLVM Team</a><br>
NAKAMURA Takumib9a33632011-04-09 02:13:37 +0000286<a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
Reid Spencer85baf762004-08-17 09:38:50 +0000287Last modified: $Date$
288</address>
289<!-- vim: sw=2
290-->
291</body>
292</html>