Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 55cbec317d9c30c8ae1d35eaa008ca63d1f2fce9 / . / docs / Passes.html
blob: 192f4420bf74296463faf5adfc67a3a0c806d370 [file] [log] [blame]
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <title>LLVM's Analysis and Transform Passes</title>
6 <link rel="stylesheet" href="llvm.css" type="text/css">
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]8</head>
9<body>
10
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]11<!--
12
13If Passes.html is up to date, the following "one-liner" should print
14an empty diff.
15
16egrep -e '^<tr><td><a href="#.*">-.*</a></td><td>.*</td></tr>$' \
17 -e '^ <a name=".*">.*</a>$' < Passes.html >html; \
18perl >help <<'EOT' && diff -u help html; rm -f help html
19open HTML, "<Passes.html" or die "open: Passes.html: $!\n";
20while (<HTML>) {
21 m:^<tr><td><a href="#(.*)">-.*</a></td><td>.*</td></tr>$: or next;
22 $order{$1} = sprintf("%03d", 1 + int %order);
23}
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]24open HELP, "../Release/bin/opt -help|" or die "open: opt -help: $!\n";
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]25while (<HELP>) {
26 m:^ -([^ ]+) +- (.*)$: or next;
27 my $o = $order{$1};
28 $o = "000" unless defined $o;
29 push @x, "$o<tr><td><a href=\"#$1\">-$1</a></td><td>$2</td></tr>\n";
30 push @y, "$o <a name=\"$1\">$2</a>\n";
31}
32@x = map { s/^\d\d\d//; $_ } sort @x;
33@y = map { s/^\d\d\d//; $_ } sort @y;
34print @x, @y;
35EOT
36
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]37This (real) one-liner can also be helpful when converting comments to HTML:
38
39perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print " <p>\n" if !$on && $_ =~ /\S/; print " </p>\n" if $on && $_ =~ /^\s*$/; print " $_\n"; $on = ($_ =~ /\S/); } print " </p>\n" if $on'
40
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]41 -->
42
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]43<div class="doc_title">LLVM's Analysis and Transform Passes</div>
44
45<ol>
46 <li><a href="#intro">Introduction</a></li>
47 <li><a href="#analyses">Analysis Passes</a>
48 <li><a href="#transforms">Transform Passes</a></li>
49 <li><a href="#utilities">Utility Passes</a></li>
50</ol>
51
52<div class="doc_author">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]53 <p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a>
54 and Gordon Henriksen</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]55</div>
56
57<!-- ======================================================================= -->
58<div class="doc_section"> <a name="intro">Introduction</a> </div>
59<div class="doc_text">
60 <p>This document serves as a high level summary of the optimization features
61 that LLVM provides. Optimizations are implemented as Passes that traverse some
62 portion of a program to either collect information or transform the program.
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]63 The table below divides the passes that LLVM provides into three categories.
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]64 Analysis passes compute information that other passes can use or for debugging
65 or program visualization purposes. Transform passes can use (or invalidate)
66 the analysis passes. Transform passes all mutate the program in some way.
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]67 Utility passes provides some utility but don't otherwise fit categorization.
Gabor Greif04367bf2007-07-06 22:07:22 +0000[diff] [blame]68 For example passes to extract functions to bitcode or write a module to
69 bitcode are neither analysis nor transform passes.
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]70 <p>The table below provides a quick summary of each pass and links to the more
71 complete pass description later in the document.</p>
72</div>
73<div class="doc_text" >
74<table>
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]75<tr><th colspan="2"><b>ANALYSIS PASSES</b></th></tr>
76<tr><th>Option</th><th>Name</th></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]77<tr><td><a href="#aa-eval">-aa-eval</a></td><td>Exhaustive Alias Analysis Precision Evaluator</td></tr>
78<tr><td><a href="#anders-aa">-anders-aa</a></td><td>Andersen's Interprocedural Alias Analysis</td></tr>
79<tr><td><a href="#basicaa">-basicaa</a></td><td>Basic Alias Analysis (default AA impl)</td></tr>
80<tr><td><a href="#basiccg">-basiccg</a></td><td>Basic CallGraph Construction</td></tr>
81<tr><td><a href="#basicvn">-basicvn</a></td><td>Basic Value Numbering (default GVN impl)</td></tr>
82<tr><td><a href="#callgraph">-callgraph</a></td><td>Print a call graph</td></tr>
83<tr><td><a href="#callscc">-callscc</a></td><td>Print SCCs of the Call Graph</td></tr>
84<tr><td><a href="#cfgscc">-cfgscc</a></td><td>Print SCCs of each function CFG</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]85<tr><td><a href="#codegenprepare">-codegenprepare</a></td><td>Optimize for code generation</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]86<tr><td><a href="#count-aa">-count-aa</a></td><td>Count Alias Analysis Query Responses</td></tr>
87<tr><td><a href="#debug-aa">-debug-aa</a></td><td>AA use debugger</td></tr>
88<tr><td><a href="#domfrontier">-domfrontier</a></td><td>Dominance Frontier Construction</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]89<tr><td><a href="#domtree">-domtree</a></td><td>Dominator Tree Construction</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]90<tr><td><a href="#externalfnconstants">-externalfnconstants</a></td><td>Print external fn callsites passed constants</td></tr>
91<tr><td><a href="#globalsmodref-aa">-globalsmodref-aa</a></td><td>Simple mod/ref analysis for globals</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]92<tr><td><a href="#instcount">-instcount</a></td><td>Counts the various types of Instructions</td></tr>
93<tr><td><a href="#intervals">-intervals</a></td><td>Interval Partition Construction</td></tr>
94<tr><td><a href="#load-vn">-load-vn</a></td><td>Load Value Numbering</td></tr>
95<tr><td><a href="#loops">-loops</a></td><td>Natural Loop Construction</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]96<tr><td><a href="#memdep">-memdep</a></td><td>Memory Dependence Analysis</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]97<tr><td><a href="#no-aa">-no-aa</a></td><td>No Alias Analysis (always returns 'may' alias)</td></tr>
98<tr><td><a href="#no-profile">-no-profile</a></td><td>No Profile Information</td></tr>
99<tr><td><a href="#postdomfrontier">-postdomfrontier</a></td><td>Post-Dominance Frontier Construction</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]100<tr><td><a href="#postdomtree">-postdomtree</a></td><td>Post-Dominator Tree Construction</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]101<tr><td><a href="#print">-print</a></td><td>Print function to stderr</td></tr>
102<tr><td><a href="#print-alias-sets">-print-alias-sets</a></td><td>Alias Set Printer</td></tr>
103<tr><td><a href="#print-callgraph">-print-callgraph</a></td><td>Print Call Graph to 'dot' file</td></tr>
104<tr><td><a href="#print-cfg">-print-cfg</a></td><td>Print CFG of function to 'dot' file</td></tr>
105<tr><td><a href="#print-cfg-only">-print-cfg-only</a></td><td>Print CFG of function to 'dot' file (with no function bodies)</td></tr>
106<tr><td><a href="#printm">-printm</a></td><td>Print module to stderr</td></tr>
107<tr><td><a href="#printusedtypes">-printusedtypes</a></td><td>Find Used Types</td></tr>
108<tr><td><a href="#profile-loader">-profile-loader</a></td><td>Load profile information from llvmprof.out</td></tr>
109<tr><td><a href="#scalar-evolution">-scalar-evolution</a></td><td>Scalar Evolution Analysis</td></tr>
110<tr><td><a href="#targetdata">-targetdata</a></td><td>Target Data Layout</td></tr>
111
112
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]113<tr><th colspan="2"><b>TRANSFORM PASSES</b></th></tr>
114<tr><th>Option</th><th>Name</th></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]115<tr><td><a href="#adce">-adce</a></td><td>Aggressive Dead Code Elimination</td></tr>
116<tr><td><a href="#argpromotion">-argpromotion</a></td><td>Promote 'by reference' arguments to scalars</td></tr>
117<tr><td><a href="#block-placement">-block-placement</a></td><td>Profile Guided Basic Block Placement</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]118<tr><td><a href="#break-crit-edges">-break-crit-edges</a></td><td>Break critical edges in CFG</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]119<tr><td><a href="#cee">-cee</a></td><td>Correlated Expression Elimination</td></tr>
120<tr><td><a href="#condprop">-condprop</a></td><td>Conditional Propagation</td></tr>
121<tr><td><a href="#constmerge">-constmerge</a></td><td>Merge Duplicate Global Constants</td></tr>
122<tr><td><a href="#constprop">-constprop</a></td><td>Simple constant propagation</td></tr>
123<tr><td><a href="#dce">-dce</a></td><td>Dead Code Elimination</td></tr>
124<tr><td><a href="#deadargelim">-deadargelim</a></td><td>Dead Argument Elimination</td></tr>
125<tr><td><a href="#deadtypeelim">-deadtypeelim</a></td><td>Dead Type Elimination</td></tr>
126<tr><td><a href="#die">-die</a></td><td>Dead Instruction Elimination</td></tr>
127<tr><td><a href="#dse">-dse</a></td><td>Dead Store Elimination</td></tr>
128<tr><td><a href="#gcse">-gcse</a></td><td>Global Common Subexpression Elimination</td></tr>
129<tr><td><a href="#globaldce">-globaldce</a></td><td>Dead Global Elimination</td></tr>
130<tr><td><a href="#globalopt">-globalopt</a></td><td>Global Variable Optimizer</td></tr>
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]131<tr><td><a href="#gvn">-gvn</a></td><td>Global Value Numbering</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]132<tr><td><a href="#gvnpre">-gvnpre</a></td><td>Global Value Numbering/Partial Redundancy Elimination</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]133<tr><td><a href="#indmemrem">-indmemrem</a></td><td>Indirect Malloc and Free Removal</td></tr>
134<tr><td><a href="#indvars">-indvars</a></td><td>Canonicalize Induction Variables</td></tr>
135<tr><td><a href="#inline">-inline</a></td><td>Function Integration/Inlining</td></tr>
136<tr><td><a href="#insert-block-profiling">-insert-block-profiling</a></td><td>Insert instrumentation for block profiling</td></tr>
137<tr><td><a href="#insert-edge-profiling">-insert-edge-profiling</a></td><td>Insert instrumentation for edge profiling</td></tr>
138<tr><td><a href="#insert-function-profiling">-insert-function-profiling</a></td><td>Insert instrumentation for function profiling</td></tr>
139<tr><td><a href="#insert-null-profiling-rs">-insert-null-profiling-rs</a></td><td>Measure profiling framework overhead</td></tr>
140<tr><td><a href="#insert-rs-profiling-framework">-insert-rs-profiling-framework</a></td><td>Insert random sampling instrumentation framework</td></tr>
141<tr><td><a href="#instcombine">-instcombine</a></td><td>Combine redundant instructions</td></tr>
142<tr><td><a href="#internalize">-internalize</a></td><td>Internalize Global Symbols</td></tr>
143<tr><td><a href="#ipconstprop">-ipconstprop</a></td><td>Interprocedural constant propagation</td></tr>
144<tr><td><a href="#ipsccp">-ipsccp</a></td><td>Interprocedural Sparse Conditional Constant Propagation</td></tr>
145<tr><td><a href="#lcssa">-lcssa</a></td><td>Loop-Closed SSA Form Pass</td></tr>
146<tr><td><a href="#licm">-licm</a></td><td>Loop Invariant Code Motion</td></tr>
147<tr><td><a href="#loop-extract">-loop-extract</a></td><td>Extract loops into new functions</td></tr>
148<tr><td><a href="#loop-extract-single">-loop-extract-single</a></td><td>Extract at most one loop into a new function</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]149<tr><td><a href="#loop-index-split">-loop-index-split</a></td><td>Index Split Loops</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]150<tr><td><a href="#loop-reduce">-loop-reduce</a></td><td>Loop Strength Reduction</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]151<tr><td><a href="#loop-rotate">-loop-rotate</a></td><td>Rotate Loops</td></tr>
152<tr><td><a href="#loop-unroll">-loop-unroll</a></td><td>Unroll loops</td></tr>
153<tr><td><a href="#loop-unswitch">-loop-unswitch</a></td><td>Unswitch loops</td></tr>
154<tr><td><a href="#loopsimplify">-loopsimplify</a></td><td>Canonicalize natural loops</td></tr>
155<tr><td><a href="#lower-packed">-lower-packed</a></td><td>lowers packed operations to operations on smaller packed datatypes</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]156<tr><td><a href="#lowerallocs">-lowerallocs</a></td><td>Lower allocations from instructions to calls</td></tr>
157<tr><td><a href="#lowergc">-lowergc</a></td><td>Lower GC intrinsics, for GCless code generators</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]158<tr><td><a href="#lowerinvoke">-lowerinvoke</a></td><td>Lower invoke and unwind, for unwindless code generators</td></tr>
159<tr><td><a href="#lowerselect">-lowerselect</a></td><td>Lower select instructions to branches</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]160<tr><td><a href="#lowersetjmp">-lowersetjmp</a></td><td>Lower Set Jump</td></tr>
161<tr><td><a href="#lowerswitch">-lowerswitch</a></td><td>Lower SwitchInst's to branches</td></tr>
162<tr><td><a href="#mem2reg">-mem2reg</a></td><td>Promote Memory to Register</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]163<tr><td><a href="#mergereturn">-mergereturn</a></td><td>Unify function exit nodes</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]164<tr><td><a href="#predsimplify">-predsimplify</a></td><td>Predicate Simplifier</td></tr>
165<tr><td><a href="#prune-eh">-prune-eh</a></td><td>Remove unused exception handling info</td></tr>
166<tr><td><a href="#raiseallocs">-raiseallocs</a></td><td>Raise allocations from calls to instructions</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]167<tr><td><a href="#reassociate">-reassociate</a></td><td>Reassociate expressions</td></tr>
168<tr><td><a href="#reg2mem">-reg2mem</a></td><td>Demote all values to stack slots</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]169<tr><td><a href="#scalarrepl">-scalarrepl</a></td><td>Scalar Replacement of Aggregates</td></tr>
170<tr><td><a href="#sccp">-sccp</a></td><td>Sparse Conditional Constant Propagation</td></tr>
171<tr><td><a href="#simplify-libcalls">-simplify-libcalls</a></td><td>Simplify well-known library calls</td></tr>
172<tr><td><a href="#simplifycfg">-simplifycfg</a></td><td>Simplify the CFG</td></tr>
173<tr><td><a href="#strip">-strip</a></td><td>Strip all symbols from a module</td></tr>
174<tr><td><a href="#tailcallelim">-tailcallelim</a></td><td>Tail Call Elimination</td></tr>
175<tr><td><a href="#tailduplicate">-tailduplicate</a></td><td>Tail Duplication</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]176
177
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]178<tr><th colspan="2"><b>UTILITY PASSES</b></th></tr>
179<tr><th>Option</th><th>Name</th></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]180<tr><td><a href="#deadarghaX0r">-deadarghaX0r</a></td><td>Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)</td></tr>
181<tr><td><a href="#extract-blocks">-extract-blocks</a></td><td>Extract Basic Blocks From Module (for bugpoint use)</td></tr>
Gabor Greif04367bf2007-07-06 22:07:22 +0000[diff] [blame]182<tr><td><a href="#emitbitcode">-emitbitcode</a></td><td>Bitcode Writer</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]183<tr><td><a href="#verify">-verify</a></td><td>Module Verifier</td></tr>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]184<tr><td><a href="#view-cfg">-view-cfg</a></td><td>View CFG of function</td></tr>
185<tr><td><a href="#view-cfg-only">-view-cfg-only</a></td><td>View CFG of function (with no function bodies)</td></tr>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]186</table>
187</div>
188
189<!-- ======================================================================= -->
190<div class="doc_section"> <a name="example">Analysis Passes</a></div>
191<div class="doc_text">
192 <p>This section describes the LLVM Analysis Passes.</p>
193</div>
194
195<!-------------------------------------------------------------------------- -->
196<div class="doc_subsection">
197 <a name="aa-eval">Exhaustive Alias Analysis Precision Evaluator</a>
198</div>
199<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]200 <p>This is a simple N^2 alias analysis accuracy evaluator.
201 Basically, for each function in the program, it simply queries to see how the
202 alias analysis implementation answers alias queries between each pair of
203 pointers in the function.</p>
204
205 <p>This is inspired and adapted from code by: Naveen Neelakantam, Francesco
206 Spadini, and Wojciech Stryjewski.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]207</div>
208
209<!-------------------------------------------------------------------------- -->
210<div class="doc_subsection">
211 <a name="anders-aa">Andersen's Interprocedural Alias Analysis</a>
212</div>
213<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]214 <p>
215 This is an implementation of Andersen's interprocedural alias
216 analysis
217 </p>
218
219 <p>
220 In pointer analysis terms, this is a subset-based, flow-insensitive,
221 field-sensitive, and context-insensitive algorithm pointer algorithm.
222 </p>
223
224 <p>
225 This algorithm is implemented as three stages:
226 </p>
227
228 <ol>
229 <li>Object identification.</li>
230 <li>Inclusion constraint identification.</li>
231 <li>Offline constraint graph optimization.</li>
232 <li>Inclusion constraint solving.</li>
233 </ol>
234
235 <p>
236 The object identification stage identifies all of the memory objects in the
237 program, which includes globals, heap allocated objects, and stack allocated
238 objects.
239 </p>
240
241 <p>
242 The inclusion constraint identification stage finds all inclusion constraints
243 in the program by scanning the program, looking for pointer assignments and
244 other statements that effect the points-to graph. For a statement like
245 <code><var>A</var> = <var>B</var></code>, this statement is processed to
246 indicate that <var>A</var> can point to anything that <var>B</var> can point
247 to. Constraints can handle copies, loads, and stores, and address taking.
248 </p>
249
250 <p>
251 The offline constraint graph optimization portion includes offline variable
252 substitution algorithms intended to computer pointer and location
253 equivalences. Pointer equivalences are those pointers that will have the
254 same points-to sets, and location equivalences are those variables that
255 always appear together in points-to sets.
256 </p>
257
258 <p>
259 The inclusion constraint solving phase iteratively propagates the inclusion
260 constraints until a fixed point is reached. This is an O(<var>n</var>³)
261 algorithm.
262 </p>
263
264 <p>
265 Function constraints are handled as if they were structs with <var>X</var>
266 fields. Thus, an access to argument <var>X</var> of function <var>Y</var> is
267 an access to node index <code>getNode(<var>Y</var>) + <var>X</var></code>.
268 This representation allows handling of indirect calls without any issues. To
269 wit, an indirect call <code><var>Y</var>(<var>a</var>,<var>b</var>)</code> is
270 equivalent to <code>*(<var>Y</var> + 1) = <var>a</var>, *(<var>Y</var> + 2) =
271 <var>b</var></code>. The return node for a function <var>F</var> is always
272 located at <code>getNode(<var>F</var>) + CallReturnPos</code>. The arguments
273 start at <code>getNode(<var>F</var>) + CallArgPos</code>.
274 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]275</div>
276
277<!-------------------------------------------------------------------------- -->
278<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]279 <a name="basicaa">Basic Alias Analysis (default AA impl)</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]280</div>
281<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]282 <p>
283 This is the default implementation of the Alias Analysis interface
284 that simply implements a few identities (two different globals cannot alias,
285 etc), but otherwise does no analysis.
286 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]287</div>
288
289<!-------------------------------------------------------------------------- -->
290<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]291 <a name="basiccg">Basic CallGraph Construction</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]292</div>
293<div class="doc_text">
294 <p>Yet to be written.</p>
295</div>
296
297<!-------------------------------------------------------------------------- -->
298<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]299 <a name="basicvn">Basic Value Numbering (default GVN impl)</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]300</div>
301<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]302 <p>
303 This is the default implementation of the <code>ValueNumbering</code>
304 interface. It walks the SSA def-use chains to trivially identify
305 lexically identical expressions. This does not require any ahead of time
306 analysis, so it is a very fast default implementation.
307 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]308</div>
309
310<!-------------------------------------------------------------------------- -->
311<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]312 <a name="callgraph">Print a call graph</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]313</div>
314<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]315 <p>
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]316 This pass, only available in <code>opt</code>, prints the call graph to
317 standard output in a human-readable form.
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]318 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]319</div>
320
321<!-------------------------------------------------------------------------- -->
322<div class="doc_subsection">
323 <a name="callscc">Print SCCs of the Call Graph</a>
324</div>
325<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]326 <p>
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]327 This pass, only available in <code>opt</code>, prints the SCCs of the call
328 graph to standard output in a human-readable form.
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]329 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]330</div>
331
332<!-------------------------------------------------------------------------- -->
333<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]334 <a name="cfgscc">Print SCCs of each function CFG</a>
335</div>
336<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]337 <p>
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]338 This pass, only available in <code>opt</code>, prints the SCCs of each
339 function CFG to standard output in a human-readable form.
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]340 </p>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]341</div>
342
343<!-------------------------------------------------------------------------- -->
344<div class="doc_subsection">
345 <a name="codegenprepare">Optimize for code generation</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]346</div>
347<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]348 <p>
349 This pass munges the code in the input function to better prepare it for
350 SelectionDAG-based code generation. This works around limitations in it's
351 basic-block-at-a-time approach. It should eventually be removed.
352 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]353</div>
354
355<!-------------------------------------------------------------------------- -->
356<div class="doc_subsection">
357 <a name="count-aa">Count Alias Analysis Query Responses</a>
358</div>
359<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]360 <p>
361 A pass which can be used to count how many alias queries
362 are being made and how the alias analysis implementation being used responds.
363 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]364</div>
365
366<!-------------------------------------------------------------------------- -->
367<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]368 <a name="debug-aa">AA use debugger</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]369</div>
370<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]371 <p>
372 This simple pass checks alias analysis users to ensure that if they
373 create a new value, they do not query AA without informing it of the value.
374 It acts as a shim over any other AA pass you want.
375 </p>
376
377 <p>
378 Yes keeping track of every value in the program is expensive, but this is
379 a debugging pass.
380 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]381</div>
382
383<!-------------------------------------------------------------------------- -->
384<div class="doc_subsection">
385 <a name="domfrontier">Dominance Frontier Construction</a>
386</div>
387<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]388 <p>
389 This pass is a simple dominator construction algorithm for finding forward
390 dominator frontiers.
391 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]392</div>
393
394<!-------------------------------------------------------------------------- -->
395<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]396 <a name="domtree">Dominator Tree Construction</a>
397</div>
398<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]399 <p>
400 This pass is a simple dominator construction algorithm for finding forward
401 dominators.
402 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]403</div>
404
405<!-------------------------------------------------------------------------- -->
406<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]407 <a name="externalfnconstants">Print external fn callsites passed constants</a>
408</div>
409<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]410 <p>
411 This pass, only available in <code>opt</code>, prints out call sites to
412 external functions that are called with constant arguments. This can be
413 useful when looking for standard library functions we should constant fold
414 or handle in alias analyses.
415 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]416</div>
417
418<!-------------------------------------------------------------------------- -->
419<div class="doc_subsection">
420 <a name="globalsmodref-aa">Simple mod/ref analysis for globals</a>
421</div>
422<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]423 <p>
424 This simple pass provides alias and mod/ref information for global values
425 that do not have their address taken, and keeps track of whether functions
426 read or write memory (are "pure"). For this simple (but very common) case,
427 we can provide pretty accurate and useful information.
428 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]429</div>
430
431<!-------------------------------------------------------------------------- -->
432<div class="doc_subsection">
433 <a name="instcount">Counts the various types of Instructions</a>
434</div>
435<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]436 <p>
437 This pass collects the count of all instructions and reports them
438 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]439</div>
440
441<!-------------------------------------------------------------------------- -->
442<div class="doc_subsection">
443 <a name="intervals">Interval Partition Construction</a>
444</div>
445<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]446 <p>
447 This analysis calculates and represents the interval partition of a function,
448 or a preexisting interval partition.
449 </p>
450
451 <p>
452 In this way, the interval partition may be used to reduce a flow graph down
453 to its degenerate single node interval partition (unless it is irreducible).
454 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]455</div>
456
457<!-------------------------------------------------------------------------- -->
458<div class="doc_subsection">
459 <a name="load-vn">Load Value Numbering</a>
460</div>
461<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]462 <p>
463 This pass value numbers load and call instructions. To do this, it finds
464 lexically identical load instructions, and uses alias analysis to determine
465 which loads are guaranteed to produce the same value. To value number call
466 instructions, it looks for calls to functions that do not write to memory
467 which do not have intervening instructions that clobber the memory that is
468 read from.
469 </p>
470
471 <p>
472 This pass builds off of another value numbering pass to implement value
473 numbering for non-load and non-call instructions. It uses Alias Analysis so
474 that it can disambiguate the load instructions. The more powerful these base
475 analyses are, the more powerful the resultant value numbering will be.
476 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]477</div>
478
479<!-------------------------------------------------------------------------- -->
480<div class="doc_subsection">
481 <a name="loops">Natural Loop Construction</a>
482</div>
483<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]484 <p>
485 This analysis is used to identify natural loops and determine the loop depth
486 of various nodes of the CFG. Note that the loops identified may actually be
487 several natural loops that share the same header node... not just a single
488 natural loop.
489 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]490</div>
491
492<!-------------------------------------------------------------------------- -->
493<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]494 <a name="memdep">Memory Dependence Analysis</a>
495</div>
496<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]497 <p>
498 An analysis that determines, for a given memory operation, what preceding
499 memory operations it depends on. It builds on alias analysis information, and
500 tries to provide a lazy, caching interface to a common kind of alias
501 information query.
502 </p>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]503</div>
504
505<!-------------------------------------------------------------------------- -->
506<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]507 <a name="no-aa">No Alias Analysis (always returns 'may' alias)</a>
508</div>
509<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]510 <p>
511 Always returns "I don't know" for alias queries. NoAA is unlike other alias
512 analysis implementations, in that it does not chain to a previous analysis. As
513 such it doesn't follow many of the rules that other alias analyses must.
514 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]515</div>
516
517<!-------------------------------------------------------------------------- -->
518<div class="doc_subsection">
519 <a name="no-profile">No Profile Information</a>
520</div>
521<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]522 <p>
523 The default "no profile" implementation of the abstract
524 <code>ProfileInfo</code> interface.
525 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]526</div>
527
528<!-------------------------------------------------------------------------- -->
529<div class="doc_subsection">
530 <a name="postdomfrontier">Post-Dominance Frontier Construction</a>
531</div>
532<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]533 <p>
534 This pass is a simple post-dominator construction algorithm for finding
535 post-dominator frontiers.
536 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]537</div>
538
539<!-------------------------------------------------------------------------- -->
540<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]541 <a name="postdomtree">Post-Dominator Tree Construction</a>
542</div>
543<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]544 <p>
545 This pass is a simple post-dominator construction algorithm for finding
546 post-dominators.
547 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]548</div>
549
550<!-------------------------------------------------------------------------- -->
551<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]552 <a name="print">Print function to stderr</a>
553</div>
554<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]555 <p>
556 The <code>PrintFunctionPass</code> class is designed to be pipelined with
557 other <code>FunctionPass</code>es, and prints out the functions of the module
558 as they are processed.
559 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]560</div>
561
562<!-------------------------------------------------------------------------- -->
563<div class="doc_subsection">
564 <a name="print-alias-sets">Alias Set Printer</a>
565</div>
566<div class="doc_text">
567 <p>Yet to be written.</p>
568</div>
569
570<!-------------------------------------------------------------------------- -->
571<div class="doc_subsection">
572 <a name="print-callgraph">Print Call Graph to 'dot' file</a>
573</div>
574<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]575 <p>
576 This pass, only available in <code>opt</code>, prints the call graph into a
577 <code>.dot</code> graph. This graph can then be processed with the "dot" tool
578 to convert it to postscript or some other suitable format.
579 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]580</div>
581
582<!-------------------------------------------------------------------------- -->
583<div class="doc_subsection">
584 <a name="print-cfg">Print CFG of function to 'dot' file</a>
585</div>
586<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]587 <p>
588 This pass, only available in <code>opt</code>, prints the control flow graph
589 into a <code>.dot</code> graph. This graph can then be processed with the
590 "dot" tool to convert it to postscript or some other suitable format.
591 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]592</div>
593
594<!-------------------------------------------------------------------------- -->
595<div class="doc_subsection">
596 <a name="print-cfg-only">Print CFG of function to 'dot' file (with no function bodies)</a>
597</div>
598<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]599 <p>
600 This pass, only available in <code>opt</code>, prints the control flow graph
601 into a <code>.dot</code> graph, omitting the function bodies. This graph can
602 then be processed with the "dot" tool to convert it to postscript or some
603 other suitable format.
604 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]605</div>
606
607<!-------------------------------------------------------------------------- -->
608<div class="doc_subsection">
609 <a name="printm">Print module to stderr</a>
610</div>
611<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]612 <p>
613 This pass simply prints out the entire module when it is executed.
614 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]615</div>
616
617<!-------------------------------------------------------------------------- -->
618<div class="doc_subsection">
619 <a name="printusedtypes">Find Used Types</a>
620</div>
621<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]622 <p>
623 This pass is used to seek out all of the types in use by the program. Note
624 that this analysis explicitly does not include types only used by the symbol
625 table.
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]626</div>
627
628<!-------------------------------------------------------------------------- -->
629<div class="doc_subsection">
630 <a name="profile-loader">Load profile information from llvmprof.out</a>
631</div>
632<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]633 <p>
634 A concrete implementation of profiling information that loads the information
635 from a profile dump file.
636 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]637</div>
638
639<!-------------------------------------------------------------------------- -->
640<div class="doc_subsection">
641 <a name="scalar-evolution">Scalar Evolution Analysis</a>
642</div>
643<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]644 <p>
645 The <code>ScalarEvolution</code> analysis can be used to analyze and
646 catagorize scalar expressions in loops. It specializes in recognizing general
647 induction variables, representing them with the abstract and opaque
648 <code>SCEV</code> class. Given this analysis, trip counts of loops and other
649 important properties can be obtained.
650 </p>
651
652 <p>
653 This analysis is primarily useful for induction variable substitution and
654 strength reduction.
655 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]656</div>
657
658<!-------------------------------------------------------------------------- -->
659<div class="doc_subsection">
660 <a name="targetdata">Target Data Layout</a>
661</div>
662<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]663 <p>Provides other passes access to information on how the size and alignment
664 required by the the target ABI for various data types.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]665</div>
666
667<!-- ======================================================================= -->
668<div class="doc_section"> <a name="transform">Transform Passes</a></div>
669<div class="doc_text">
670 <p>This section describes the LLVM Transform Passes.</p>
671</div>
672
673<!-------------------------------------------------------------------------- -->
674<div class="doc_subsection">
675 <a name="adce">Aggressive Dead Code Elimination</a>
676</div>
677<div class="doc_text">
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]678 <p>ADCE aggressively tries to eliminate code. This pass is similar to
679 <a href="#dce">DCE</a> but it assumes that values are dead until proven
680 otherwise. This is similar to <a href="#sccp">SCCP</a>, except applied to
681 the liveness of values.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]682</div>
683
684<!-------------------------------------------------------------------------- -->
685<div class="doc_subsection">
686 <a name="argpromotion">Promote 'by reference' arguments to scalars</a>
687</div>
688<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]689 <p>
690 This pass promotes "by reference" arguments to be "by value" arguments. In
691 practice, this means looking for internal functions that have pointer
692 arguments. If it can prove, through the use of alias analysis, that an
693 argument is *only* loaded, then it can pass the value into the function
694 instead of the address of the value. This can cause recursive simplification
695 of code and lead to the elimination of allocas (especially in C++ template
696 code like the STL).
697 </p>
698
699 <p>
700 This pass also handles aggregate arguments that are passed into a function,
701 scalarizing them if the elements of the aggregate are only loaded. Note that
702 it refuses to scalarize aggregates which would require passing in more than
703 three operands to the function, because passing thousands of operands for a
704 large array or structure is unprofitable!
705 </p>
706
707 <p>
708 Note that this transformation could also be done for arguments that are only
709 stored to (returning the value instead), but does not currently. This case
710 would be best handled when and if LLVM starts supporting multiple return
711 values from functions.
712 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]713</div>
714
715<!-------------------------------------------------------------------------- -->
716<div class="doc_subsection">
717 <a name="block-placement">Profile Guided Basic Block Placement</a>
718</div>
719<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]720 <p>This pass is a very simple profile guided basic block placement algorithm.
721 The idea is to put frequently executed blocks together at the start of the
722 function and hopefully increase the number of fall-through conditional
723 branches. If there is no profile information for a particular function, this
724 pass basically orders blocks in depth-first order.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]725</div>
726
727<!-------------------------------------------------------------------------- -->
728<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]729 <a name="break-crit-edges">Break critical edges in CFG</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]730</div>
731<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]732 <p>
733 Break all of the critical edges in the CFG by inserting a dummy basic block.
734 It may be "required" by passes that cannot deal with critical edges. This
735 transformation obviously invalidates the CFG, but can update forward dominator
736 (set, immediate dominators, tree, and frontier) information.
737 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]738</div>
739
740<!-------------------------------------------------------------------------- -->
741<div class="doc_subsection">
742 <a name="cee">Correlated Expression Elimination</a>
743</div>
744<div class="doc_text">
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]745 <p>Correlated Expression Elimination propagates information from conditional
746 branches to blocks dominated by destinations of the branch. It propagates
747 information from the condition check itself into the body of the branch,
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]748 allowing transformations like these for example:</p>
749
750<blockquote><pre>
751if (i == 7)
752 ... 4*i; // constant propagation
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]753
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]754M = i+1; N = j+1;
755if (i == j)
756 X = M-N; // = M-M == 0;
757</pre></blockquote>
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]758
759 <p>This is called Correlated Expression Elimination because we eliminate or
760 simplify expressions that are correlated with the direction of a branch. In
761 this way we use static information to give us some information about the
762 dynamic value of a variable.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]763</div>
764
765<!-------------------------------------------------------------------------- -->
766<div class="doc_subsection">
767 <a name="condprop">Conditional Propagation</a>
768</div>
769<div class="doc_text">
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]770 <p>This pass propagates information about conditional expressions through the
771 program, allowing it to eliminate conditional branches in some cases.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]772</div>
773
774<!-------------------------------------------------------------------------- -->
775<div class="doc_subsection">
776 <a name="constmerge">Merge Duplicate Global Constants</a>
777</div>
778<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]779 <p>
780 Merges duplicate global constants together into a single constant that is
781 shared. This is useful because some passes (ie TraceValues) insert a lot of
782 string constants into the program, regardless of whether or not an existing
783 string is available.
784 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]785</div>
786
787<!-------------------------------------------------------------------------- -->
788<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]789 <a name="constprop">Simple constant propagation</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]790</div>
791<div class="doc_text">
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]792 <p>This file implements constant propagation and merging. It looks for
793 instructions involving only constant operands and replaces them with a
Gordon Henriksenddaa61d2007-10-25 08:58:56 +0000[diff] [blame]794 constant value instead of an instruction. For example:</p>
795 <blockquote><pre>add i32 1, 2</pre></blockquote>
796 <p>becomes</p>
797 <blockquote><pre>i32 3</pre></blockquote>
Reid Spenceraf4af3a2007-03-27 02:49:31 +0000[diff] [blame]798 <p>NOTE: this pass has a habit of making definitions be dead. It is a good
799 idea to to run a <a href="#die">DIE</a> (Dead Instruction Elimination) pass
800 sometime after running this pass.</p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]801</div>
802
803<!-------------------------------------------------------------------------- -->
804<div class="doc_subsection">
805 <a name="dce">Dead Code Elimination</a>
806</div>
807<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]808 <p>
809 Dead code elimination is similar to <a href="#die">dead instruction
810 elimination</a>, but it rechecks instructions that were used by removed
811 instructions to see if they are newly dead.
812 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]813</div>
814
815<!-------------------------------------------------------------------------- -->
816<div class="doc_subsection">
817 <a name="deadargelim">Dead Argument Elimination</a>
818</div>
819<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]820 <p>
821 This pass deletes dead arguments from internal functions. Dead argument
822 elimination removes arguments which are directly dead, as well as arguments
823 only passed into function calls as dead arguments of other functions. This
824 pass also deletes dead arguments in a similar way.
825 </p>
826
827 <p>
828 This pass is often useful as a cleanup pass to run after aggressive
829 interprocedural passes, which add possibly-dead arguments.
830 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]831</div>
832
833<!-------------------------------------------------------------------------- -->
834<div class="doc_subsection">
835 <a name="deadtypeelim">Dead Type Elimination</a>
836</div>
837<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]838 <p>
839 This pass is used to cleanup the output of GCC. It eliminate names for types
840 that are unused in the entire translation unit, using the <a
841 href="#findusedtypes">find used types</a> pass.
842 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]843</div>
844
845<!-------------------------------------------------------------------------- -->
846<div class="doc_subsection">
847 <a name="die">Dead Instruction Elimination</a>
848</div>
849<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]850 <p>
851 Dead instruction elimination performs a single pass over the function,
852 removing instructions that are obviously dead.
853 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]854</div>
855
856<!-------------------------------------------------------------------------- -->
857<div class="doc_subsection">
858 <a name="dse">Dead Store Elimination</a>
859</div>
860<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]861 <p>
862 A trivial dead store elimination that only considers basic-block local
863 redundant stores.
864 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]865</div>
866
867<!-------------------------------------------------------------------------- -->
868<div class="doc_subsection">
869 <a name="gcse">Global Common Subexpression Elimination</a>
870</div>
871<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]872 <p>
873 This pass is designed to be a very quick global transformation that
874 eliminates global common subexpressions from a function. It does this by
875 using an existing value numbering implementation to identify the common
876 subexpressions, eliminating them when possible.
877 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]878</div>
879
880<!-------------------------------------------------------------------------- -->
881<div class="doc_subsection">
882 <a name="globaldce">Dead Global Elimination</a>
883</div>
884<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]885 <p>
886 This transform is designed to eliminate unreachable internal globals from the
887 program. It uses an aggressive algorithm, searching out globals that are
888 known to be alive. After it finds all of the globals which are needed, it
889 deletes whatever is left over. This allows it to delete recursive chunks of
890 the program which are unreachable.
891 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]892</div>
893
894<!-------------------------------------------------------------------------- -->
895<div class="doc_subsection">
896 <a name="globalopt">Global Variable Optimizer</a>
897</div>
898<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]899 <p>
900 This pass transforms simple global variables that never have their address
901 taken. If obviously true, it marks read/write globals as constant, deletes
902 variables only stored to, etc.
903 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]904</div>
905
906<!-------------------------------------------------------------------------- -->
907<div class="doc_subsection">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]908 <a name="gvn">Global Value Numbering</a>
909</div>
910<div class="doc_text">
911 <p>
912 This pass performs global value numbering to eliminate fully redundant
913 instructions. It also performs simple dead load elimination.
914 </p>
915</div>
916
917<!-------------------------------------------------------------------------- -->
918<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]919 <a name="gvnpre">Global Value Numbering/Partial Redundancy Elimination</a>
920</div>
921<div class="doc_text">
Gordon Henriksen0e15dc22007-10-25 10:18:27 +0000[diff] [blame]922 <p>
923 This pass performs a hybrid of global value numbering and partial redundancy
924 elimination, known as GVN-PRE. It performs partial redundancy elimination on
925 values, rather than lexical expressions, allowing a more comprehensive view
926 the optimization. It replaces redundant values with uses of earlier
927 occurences of the same value. While this is beneficial in that it eliminates
928 unneeded computation, it also increases register pressure by creating large
929 live ranges, and should be used with caution on platforms that are very
930 sensitive to register pressure.
931 </p>
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]932</div>
933
934<!-------------------------------------------------------------------------- -->
935<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]936 <a name="indmemrem">Indirect Malloc and Free Removal</a>
937</div>
938<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]939 <p>
940 This pass finds places where memory allocation functions may escape into
941 indirect land. Some transforms are much easier (aka possible) only if free
942 or malloc are not called indirectly.
943 </p>
944
945 <p>
946 Thus find places where the address of memory functions are taken and construct
947 bounce functions with direct calls of those functions.
948 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]949</div>
950
951<!-------------------------------------------------------------------------- -->
952<div class="doc_subsection">
953 <a name="indvars">Canonicalize Induction Variables</a>
954</div>
955<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]956 <p>
957 This transformation analyzes and transforms the induction variables (and
958 computations derived from them) into simpler forms suitable for subsequent
959 analysis and transformation.
960 </p>
961
962 <p>
963 This transformation makes the following changes to each loop with an
964 identifiable induction variable:
965 </p>
966
967 <ol>
968 <li>All loops are transformed to have a <em>single</em> canonical
969 induction variable which starts at zero and steps by one.</li>
970 <li>The canonical induction variable is guaranteed to be the first PHI node
971 in the loop header block.</li>
972 <li>Any pointer arithmetic recurrences are raised to use array
973 subscripts.</li>
974 </ol>
975
976 <p>
977 If the trip count of a loop is computable, this pass also makes the following
978 changes:
979 </p>
980
981 <ol>
982 <li>The exit condition for the loop is canonicalized to compare the
983 induction value against the exit value. This turns loops like:
984 <blockquote><pre>for (i = 7; i*i < 1000; ++i)</pre></blockquote>
985 into
986 <blockquote><pre>for (i = 0; i != 25; ++i)</pre></blockquote></li>
987 <li>Any use outside of the loop of an expression derived from the indvar
988 is changed to compute the derived value outside of the loop, eliminating
989 the dependence on the exit value of the induction variable. If the only
990 purpose of the loop is to compute the exit value of some derived
991 expression, this transformation will make the loop dead.</li>
992 </p>
993
994 <p>
995 This transformation should be followed by strength reduction after all of the
996 desired loop transformations have been performed. Additionally, on targets
997 where it is profitable, the loop could be transformed to count down to zero
998 (the "do loop" optimization).
999 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1000</div>
1001
1002<!-------------------------------------------------------------------------- -->
1003<div class="doc_subsection">
1004 <a name="inline">Function Integration/Inlining</a>
1005</div>
1006<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1007 <p>
1008 Bottom-up inlining of functions into callees.
1009 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1010</div>
1011
1012<!-------------------------------------------------------------------------- -->
1013<div class="doc_subsection">
1014 <a name="insert-block-profiling">Insert instrumentation for block profiling</a>
1015</div>
1016<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1017 <p>
1018 This pass instruments the specified program with counters for basic block
1019 profiling, which counts the number of times each basic block executes. This
1020 is the most basic form of profiling, which can tell which blocks are hot, but
1021 cannot reliably detect hot paths through the CFG.
1022 </p>
1023
1024 <p>
1025 Note that this implementation is very naïve. Control equivalent regions of
1026 the CFG should not require duplicate counters, but it does put duplicate
1027 counters in.
1028 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1029</div>
1030
1031<!-------------------------------------------------------------------------- -->
1032<div class="doc_subsection">
1033 <a name="insert-edge-profiling">Insert instrumentation for edge profiling</a>
1034</div>
1035<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1036 <p>
1037 This pass instruments the specified program with counters for edge profiling.
1038 Edge profiling can give a reasonable approximation of the hot paths through a
1039 program, and is used for a wide variety of program transformations.
1040 </p>
1041
1042 <p>
1043 Note that this implementation is very naïve. It inserts a counter for
1044 <em>every</em> edge in the program, instead of using control flow information
1045 to prune the number of counters inserted.
1046 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1047</div>
1048
1049<!-------------------------------------------------------------------------- -->
1050<div class="doc_subsection">
1051 <a name="insert-function-profiling">Insert instrumentation for function profiling</a>
1052</div>
1053<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1054 <p>
1055 This pass instruments the specified program with counters for function
1056 profiling, which counts the number of times each function is called.
1057 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1058</div>
1059
1060<!-------------------------------------------------------------------------- -->
1061<div class="doc_subsection">
1062 <a name="insert-null-profiling-rs">Measure profiling framework overhead</a>
1063</div>
1064<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1065 <p>
1066 The basic profiler that does nothing. It is the default profiler and thus
1067 terminates <code>RSProfiler</code> chains. It is useful for measuring
1068 framework overhead.
1069 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1070</div>
1071
1072<!-------------------------------------------------------------------------- -->
1073<div class="doc_subsection">
1074 <a name="insert-rs-profiling-framework">Insert random sampling instrumentation framework</a>
1075</div>
1076<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1077 <p>
1078 The second stage of the random-sampling instrumentation framework, duplicates
1079 all instructions in a function, ignoring the profiling code, then connects the
1080 two versions together at the entry and at backedges. At each connection point
1081 a choice is made as to whether to jump to the profiled code (take a sample) or
1082 execute the unprofiled code.
1083 </p>
1084
1085 <p>
1086 After this pass, it is highly recommended to run<a href="#mem2reg">mem2reg</a>
1087 and <a href="#adce">adce</a>. <a href="#instcombine">instcombine</a>,
1088 <a href="#load-vn">load-vn</a>, <a href="#gdce">gdce</a>, and
1089 <a href="#dse">dse</a> also are good to run afterwards.
1090 </p>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1091</div>
1092
1093<!-------------------------------------------------------------------------- -->
1094<div class="doc_subsection">
1095 <a name="instcombine">Combine redundant instructions</a>
1096</div>
1097<div class="doc_text">
Gordon Henriksen55cbec32007-10-26 03:03:51 +0000[diff] [blame^]1098 <p>
1099 Combine instructions to form fewer, simple
1100 instructions. This pass does not modify the CFG This pass is where algebraic
1101 simplification happens.
1102 </p>
1103
1104 <p>
1105 This pass combines things like:
1106 </p>
1107
1108<blockquote><pre
1109>%Y = add i32 %X, 1
1110%Z = add i32 %Y, 1</pre></blockquote>
1111
1112 <p>
1113 into:
1114 </p>
1115
1116<blockquote><pre
1117>%Z = add i32 %X, 2</pre></blockquote>
1118
1119 <p>
1120 This is a simple worklist driven algorithm.
1121 </p>
1122
1123 <p>
1124 This pass guarantees that the following canonicalizations are performed on
1125 the program:
1126 </p>
1127
1128 <ul>
1129 <li>If a binary operator has a constant operand, it is moved to the right-
1130 hand side.</li>
1131 <li>Bitwise operators with constant operands are always grouped so that
1132 shifts are performed first, then <code>or</code>s, then
1133 <code>and</code>s, then <code>xor</code>s.</li>
1134 <li>Compare instructions are converted from <code>&lt;</code>,
1135 <code>&gt;</code>, <code>≤</code>, or <code>≥</code> to
1136 <code>=</code> or <code>≠</code> if possible.</li>
1137 <li>All <code>cmp</code> instructions on boolean values are replaced with
1138 logical operations.</li>
1139 <li><code>add <var>X</var>, <var>X</var></code> is represented as
1140 <code>mul <var>X</var>, 2</code> ⇒ <code>shl <var>X</var>, 1</code></li>
1141 <li>Multiplies with a constant power-of-two argument are transformed into
1142 shifts.</li>
1143 <li>… etc.</li>
1144 </ul>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1145</div>
1146
1147<!-------------------------------------------------------------------------- -->
1148<div class="doc_subsection">
1149 <a name="internalize">Internalize Global Symbols</a>
1150</div>
1151<div class="doc_text">
1152 <p>Yet to be written.</p>
1153</div>
1154
1155<!-------------------------------------------------------------------------- -->
1156<div class="doc_subsection">
1157 <a name="ipconstprop">Interprocedural constant propagation</a>
1158</div>
1159<div class="doc_text">
1160 <p>Yet to be written.</p>
1161</div>
1162
1163<!-------------------------------------------------------------------------- -->
1164<div class="doc_subsection">
1165 <a name="ipsccp">Interprocedural Sparse Conditional Constant Propagation</a>
1166</div>
1167<div class="doc_text">
1168 <p>Yet to be written.</p>
1169</div>
1170
1171<!-------------------------------------------------------------------------- -->
1172<div class="doc_subsection">
1173 <a name="lcssa">Loop-Closed SSA Form Pass</a>
1174</div>
1175<div class="doc_text">
1176 <p>Yet to be written.</p>
1177</div>
1178
1179<!-------------------------------------------------------------------------- -->
1180<div class="doc_subsection">
1181 <a name="licm">Loop Invariant Code Motion</a>
1182</div>
1183<div class="doc_text">
1184 <p>Yet to be written.</p>
1185</div>
1186
1187<!-------------------------------------------------------------------------- -->
1188<div class="doc_subsection">
1189 <a name="loop-extract">Extract loops into new functions</a>
1190</div>
1191<div class="doc_text">
1192 <p>Yet to be written.</p>
1193</div>
1194
1195<!-------------------------------------------------------------------------- -->
1196<div class="doc_subsection">
1197 <a name="loop-extract-single">Extract at most one loop into a new function</a>
1198</div>
1199<div class="doc_text">
1200 <p>Yet to be written.</p>
1201</div>
1202
1203<!-------------------------------------------------------------------------- -->
1204<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1205 <a name="loop-index-split">Index Split Loops</a>
1206</div>
1207<div class="doc_text">
1208 <p>Yet to be written.</p>
1209</div>
1210
1211<!-------------------------------------------------------------------------- -->
1212<div class="doc_subsection">
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1213 <a name="loop-reduce">Loop Strength Reduction</a>
1214</div>
1215<div class="doc_text">
1216 <p>Yet to be written.</p>
1217</div>
1218
1219<!-------------------------------------------------------------------------- -->
1220<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1221 <a name="loop-rotate">Rotate Loops</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1222</div>
1223<div class="doc_text">
1224 <p>Yet to be written.</p>
1225</div>
1226
1227<!-------------------------------------------------------------------------- -->
1228<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1229 <a name="loop-unroll">Unroll loops</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1230</div>
1231<div class="doc_text">
1232 <p>Yet to be written.</p>
1233</div>
1234
1235<!-------------------------------------------------------------------------- -->
1236<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1237 <a name="loop-unswitch">Unswitch loops</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1238</div>
1239<div class="doc_text">
1240 <p>Yet to be written.</p>
1241</div>
1242
1243<!-------------------------------------------------------------------------- -->
1244<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1245 <a name="loopsimplify">Canonicalize natural loops</a>
1246</div>
1247<div class="doc_text">
1248 <p>Yet to be written.</p>
1249</div>
1250
1251<!-------------------------------------------------------------------------- -->
1252<div class="doc_subsection">
1253 <a name="lower-packed">lowers packed operations to operations on smaller packed datatypes</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1254</div>
1255<div class="doc_text">
1256 <p>Yet to be written.</p>
1257</div>
1258
1259<!-------------------------------------------------------------------------- -->
1260<div class="doc_subsection">
1261 <a name="lowerallocs">Lower allocations from instructions to calls</a>
1262</div>
1263<div class="doc_text">
1264 <p>Yet to be written.</p>
1265</div>
1266
1267<!-------------------------------------------------------------------------- -->
1268<div class="doc_subsection">
1269 <a name="lowergc">Lower GC intrinsics, for GCless code generators</a>
1270</div>
1271<div class="doc_text">
1272 <p>Yet to be written.</p>
1273</div>
1274
1275<!-------------------------------------------------------------------------- -->
1276<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1277 <a name="lowerinvoke">Lower invoke and unwind, for unwindless code generators</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1278</div>
1279<div class="doc_text">
1280 <p>Yet to be written.</p>
1281</div>
1282
1283<!-------------------------------------------------------------------------- -->
1284<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1285 <a name="lowerselect">Lower select instructions to branches</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1286</div>
1287<div class="doc_text">
1288 <p>Yet to be written.</p>
1289</div>
1290
1291<!-------------------------------------------------------------------------- -->
1292<div class="doc_subsection">
1293 <a name="lowersetjmp">Lower Set Jump</a>
1294</div>
1295<div class="doc_text">
1296 <p>Yet to be written.</p>
1297</div>
1298
1299<!-------------------------------------------------------------------------- -->
1300<div class="doc_subsection">
1301 <a name="lowerswitch">Lower SwitchInst's to branches</a>
1302</div>
1303<div class="doc_text">
1304 <p>Yet to be written.</p>
1305</div>
1306
1307<!-------------------------------------------------------------------------- -->
1308<div class="doc_subsection">
1309 <a name="mem2reg">Promote Memory to Register</a>
1310</div>
1311<div class="doc_text">
1312 <p>Yet to be written.</p>
1313</div>
1314
1315<!-------------------------------------------------------------------------- -->
1316<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1317 <a name="mergereturn">Unify function exit nodes</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1318</div>
1319<div class="doc_text">
1320 <p>Yet to be written.</p>
1321</div>
1322
1323<!-------------------------------------------------------------------------- -->
1324<div class="doc_subsection">
1325 <a name="predsimplify">Predicate Simplifier</a>
1326</div>
1327<div class="doc_text">
1328 <p>Yet to be written.</p>
1329</div>
1330
1331<!-------------------------------------------------------------------------- -->
1332<div class="doc_subsection">
1333 <a name="prune-eh">Remove unused exception handling info</a>
1334</div>
1335<div class="doc_text">
1336 <p>Yet to be written.</p>
1337</div>
1338
1339<!-------------------------------------------------------------------------- -->
1340<div class="doc_subsection">
1341 <a name="raiseallocs">Raise allocations from calls to instructions</a>
1342</div>
1343<div class="doc_text">
1344 <p>Yet to be written.</p>
1345</div>
1346
1347<!-------------------------------------------------------------------------- -->
1348<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1349 <a name="reassociate">Reassociate expressions</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1350</div>
1351<div class="doc_text">
1352 <p>Yet to be written.</p>
1353</div>
1354
1355<!-------------------------------------------------------------------------- -->
1356<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1357 <a name="reg2mem">Demote all values to stack slots</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1358</div>
1359<div class="doc_text">
1360 <p>Yet to be written.</p>
1361</div>
1362
1363<!-------------------------------------------------------------------------- -->
1364<div class="doc_subsection">
1365 <a name="scalarrepl">Scalar Replacement of Aggregates</a>
1366</div>
1367<div class="doc_text">
1368 <p>Yet to be written.</p>
1369</div>
1370
1371<!-------------------------------------------------------------------------- -->
1372<div class="doc_subsection">
1373 <a name="sccp">Sparse Conditional Constant Propagation</a>
1374</div>
1375<div class="doc_text">
1376 <p>Yet to be written.</p>
1377</div>
1378
1379<!-------------------------------------------------------------------------- -->
1380<div class="doc_subsection">
1381 <a name="simplify-libcalls">Simplify well-known library calls</a>
1382</div>
1383<div class="doc_text">
1384 <p>Yet to be written.</p>
1385</div>
1386
1387<!-------------------------------------------------------------------------- -->
1388<div class="doc_subsection">
1389 <a name="simplifycfg">Simplify the CFG</a>
1390</div>
1391<div class="doc_text">
1392 <p>Yet to be written.</p>
1393</div>
1394
1395<!-------------------------------------------------------------------------- -->
1396<div class="doc_subsection">
1397 <a name="strip">Strip all symbols from a module</a>
1398</div>
1399<div class="doc_text">
1400 <p>Yet to be written.</p>
1401</div>
1402
1403<!-------------------------------------------------------------------------- -->
1404<div class="doc_subsection">
1405 <a name="tailcallelim">Tail Call Elimination</a>
1406</div>
1407<div class="doc_text">
1408 <p>Yet to be written.</p>
1409</div>
1410
1411<!-------------------------------------------------------------------------- -->
1412<div class="doc_subsection">
1413 <a name="tailduplicate">Tail Duplication</a>
1414</div>
1415<div class="doc_text">
1416 <p>Yet to be written.</p>
1417</div>
1418
1419<!-- ======================================================================= -->
1420<div class="doc_section"> <a name="transform">Utility Passes</a></div>
1421<div class="doc_text">
1422 <p>This section describes the LLVM Utility Passes.</p>
1423</div>
1424
1425<!-------------------------------------------------------------------------- -->
1426<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1427 <a name="deadarghaX0r">Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1428</div>
1429<div class="doc_text">
1430 <p>Yet to be written.</p>
1431</div>
1432
1433<!-------------------------------------------------------------------------- -->
1434<div class="doc_subsection">
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1435 <a name="extract-blocks">Extract Basic Blocks From Module (for bugpoint use)</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1436</div>
1437<div class="doc_text">
1438 <p>Yet to be written.</p>
1439</div>
1440
1441<!-------------------------------------------------------------------------- -->
1442<div class="doc_subsection">
Gabor Greif04367bf2007-07-06 22:07:22 +0000[diff] [blame]1443 <a name="emitbitcode">Bitcode Writer</a>
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1444</div>
1445<div class="doc_text">
1446 <p>Yet to be written.</p>
1447</div>
1448
1449<!-------------------------------------------------------------------------- -->
1450<div class="doc_subsection">
1451 <a name="verify">Module Verifier</a>
1452</div>
1453<div class="doc_text">
1454 <p>Yet to be written.</p>
1455</div>
1456
Gordon Henriksen1f5cce02007-10-25 08:46:12 +0000[diff] [blame]1457<!-------------------------------------------------------------------------- -->
1458<div class="doc_subsection">
1459 <a name="view-cfg">View CFG of function</a>
1460</div>
1461<div class="doc_text">
1462 <p>Yet to be written.</p>
1463</div>
1464
1465<!-------------------------------------------------------------------------- -->
1466<div class="doc_subsection">
1467 <a name="view-cfg-only">View CFG of function (with no function bodies)</a>
1468</div>
1469<div class="doc_text">
1470 <p>Yet to be written.</p>
1471</div>
1472
Reid Spencerd9aac122007-03-26 09:32:31 +0000[diff] [blame]1473<!-- *********************************************************************** -->
1474
1475<hr>
1476<address>
1477 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1478 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
1479 <a href="http://validator.w3.org/check/referer"><img
1480 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
1481
1482 <a href="mailto:rspencer@x10sys.com">Reid Spencer</a><br>
1483 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
1484 Last modified: $Date$
1485</address>
1486
1487</body>
1488</html>