<head>
<title>LLVM's Analysis and Transform Passes</title>
<link rel="stylesheet" href="llvm.css" type="text/css">
+ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
+<!--
+
+If Passes.html is up to date, the following "one-liner" should print
+an empty diff.
+
+egrep -e '^<tr><td><a href="#.*">-.*</a></td><td>.*</td></tr>$' \
+ -e '^ <a name=".*">.*</a>$' < Passes.html >html; \
+perl >help <<'EOT' && diff -u help html; rm -f help html
+open HTML, "<Passes.html" or die "open: Passes.html: $!\n";
+while (<HTML>) {
+ m:^<tr><td><a href="#(.*)">-.*</a></td><td>.*</td></tr>$: or next;
+ $order{$1} = sprintf("%03d", 1 + int %order);
+}
+open HELP, "../Release/bin/opt -help|" or die "open: opt -help: $!\n";
+while (<HELP>) {
+ m:^ -([^ ]+) +- (.*)$: or next;
+ my $o = $order{$1};
+ $o = "000" unless defined $o;
+ push @x, "$o<tr><td><a href=\"#$1\">-$1</a></td><td>$2</td></tr>\n";
+ push @y, "$o <a name=\"$1\">$2</a>\n";
+}
+@x = map { s/^\d\d\d//; $_ } sort @x;
+@y = map { s/^\d\d\d//; $_ } sort @y;
+print @x, @y;
+EOT
+
+This (real) one-liner can also be helpful when converting comments to HTML:
+
+perl -e '$/ = 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'
+
+ -->
+
<div class="doc_title">LLVM's Analysis and Transform Passes</div>
<ol>
</ol>
<div class="doc_author">
- <p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a></p>
+ <p>Written by <a href="mailto:rspencer@x10sys.com">Reid Spencer</a>
+ and Gordon Henriksen</p>
</div>
<!-- ======================================================================= -->
<p>This document serves as a high level summary of the optimization features
that LLVM provides. Optimizations are implemented as Passes that traverse some
portion of a program to either collect information or transform the program.
- THe table below divides the passes that LLVM provides into three categories.
+ The table below divides the passes that LLVM provides into three categories.
Analysis passes compute information that other passes can use or for debugging
or program visualization purposes. Transform passes can use (or invalidate)
the analysis passes. Transform passes all mutate the program in some way.
- Utility passes provides ome utility but don't otherwise fit categorization.
+ Utility passes provides some utility but don't otherwise fit categorization.
For example passes to extract functions to bitcode or write a module to
bitcode are neither analysis nor transform passes.
<p>The table below provides a quick summary of each pass and links to the more
</div>
<div class="doc_text" >
<table>
-<tr><th colspan="3"><b>ANALYSIS PASSES</b></th></tr>
-<tr><th>Option</th><th>Name</th><th>Directory</th></tr>
+<tr><th colspan="2"><b>ANALYSIS PASSES</b></th></tr>
+<tr><th>Option</th><th>Name</th></tr>
<tr><td><a href="#aa-eval">-aa-eval</a></td><td>Exhaustive Alias Analysis Precision Evaluator</td></tr>
<tr><td><a href="#anders-aa">-anders-aa</a></td><td>Andersen's Interprocedural Alias Analysis</td></tr>
<tr><td><a href="#basicaa">-basicaa</a></td><td>Basic Alias Analysis (default AA impl)</td></tr>
<tr><td><a href="#callgraph">-callgraph</a></td><td>Print a call graph</td></tr>
<tr><td><a href="#callscc">-callscc</a></td><td>Print SCCs of the Call Graph</td></tr>
<tr><td><a href="#cfgscc">-cfgscc</a></td><td>Print SCCs of each function CFG</td></tr>
+<tr><td><a href="#codegenprepare">-codegenprepare</a></td><td>Optimize for code generation</td></tr>
<tr><td><a href="#count-aa">-count-aa</a></td><td>Count Alias Analysis Query Responses</td></tr>
<tr><td><a href="#debug-aa">-debug-aa</a></td><td>AA use debugger</td></tr>
<tr><td><a href="#domfrontier">-domfrontier</a></td><td>Dominance Frontier Construction</td></tr>
-<tr><td><a href="#domset">-domset</a></td><td>Dominator Set Construction</td></tr>
<tr><td><a href="#domtree">-domtree</a></td><td>Dominator Tree Construction</td></tr>
-<tr><td><a href="#etforest">-etforest</a></td><td>ET Forest Construction</td></tr>
<tr><td><a href="#externalfnconstants">-externalfnconstants</a></td><td>Print external fn callsites passed constants</td></tr>
<tr><td><a href="#globalsmodref-aa">-globalsmodref-aa</a></td><td>Simple mod/ref analysis for globals</td></tr>
-<tr><td><a href="#idom">-idom</a></td><td>Immediate Dominators Construction</td></tr>
<tr><td><a href="#instcount">-instcount</a></td><td>Counts the various types of Instructions</td></tr>
<tr><td><a href="#intervals">-intervals</a></td><td>Interval Partition Construction</td></tr>
<tr><td><a href="#load-vn">-load-vn</a></td><td>Load Value Numbering</td></tr>
<tr><td><a href="#loops">-loops</a></td><td>Natural Loop Construction</td></tr>
+<tr><td><a href="#memdep">-memdep</a></td><td>Memory Dependence Analysis</td></tr>
<tr><td><a href="#no-aa">-no-aa</a></td><td>No Alias Analysis (always returns 'may' alias)</td></tr>
<tr><td><a href="#no-profile">-no-profile</a></td><td>No Profile Information</td></tr>
<tr><td><a href="#postdomfrontier">-postdomfrontier</a></td><td>Post-Dominance Frontier Construction</td></tr>
-<tr><td><a href="#postdomset">-postdomset</a></td><td>Post-Dominator Set Construction</td></tr>
<tr><td><a href="#postdomtree">-postdomtree</a></td><td>Post-Dominator Tree Construction</td></tr>
-<tr><td><a href="#postetforest">-postetforest</a></td><td>Post-ET-Forest Construction</td></tr>
-<tr><td><a href="#postidom">-postidom</a></td><td>Immediate Post-Dominators Construction</td></tr>
<tr><td><a href="#print">-print</a></td><td>Print function to stderr</td></tr>
<tr><td><a href="#print-alias-sets">-print-alias-sets</a></td><td>Alias Set Printer</td></tr>
<tr><td><a href="#print-callgraph">-print-callgraph</a></td><td>Print Call Graph to 'dot' file</td></tr>
<tr><td><a href="#targetdata">-targetdata</a></td><td>Target Data Layout</td></tr>
-<tr><th colspan="3"><b>TRANSFORM PASSES</b></th></tr>
-<tr><th>Option</th><th>Name</th><th>Directory</th></tr>
+<tr><th colspan="2"><b>TRANSFORM PASSES</b></th></tr>
+<tr><th>Option</th><th>Name</th></tr>
<tr><td><a href="#adce">-adce</a></td><td>Aggressive Dead Code Elimination</td></tr>
<tr><td><a href="#argpromotion">-argpromotion</a></td><td>Promote 'by reference' arguments to scalars</td></tr>
<tr><td><a href="#block-placement">-block-placement</a></td><td>Profile Guided Basic Block Placement</td></tr>
-<tr><td><a href="#break-crit-edges">-break-crit-edges</a></td><td>Break Critical Edges in CFG</td></tr>
+<tr><td><a href="#break-crit-edges">-break-crit-edges</a></td><td>Break critical edges in CFG</td></tr>
<tr><td><a href="#cee">-cee</a></td><td>Correlated Expression Elimination</td></tr>
<tr><td><a href="#condprop">-condprop</a></td><td>Conditional Propagation</td></tr>
<tr><td><a href="#constmerge">-constmerge</a></td><td>Merge Duplicate Global Constants</td></tr>
<tr><td><a href="#gcse">-gcse</a></td><td>Global Common Subexpression Elimination</td></tr>
<tr><td><a href="#globaldce">-globaldce</a></td><td>Dead Global Elimination</td></tr>
<tr><td><a href="#globalopt">-globalopt</a></td><td>Global Variable Optimizer</td></tr>
+<tr><td><a href="#gvn">-gvn</a></td><td>Global Value Numbering</td></tr>
+<tr><td><a href="#gvnpre">-gvnpre</a></td><td>Global Value Numbering/Partial Redundancy Elimination</td></tr>
<tr><td><a href="#indmemrem">-indmemrem</a></td><td>Indirect Malloc and Free Removal</td></tr>
<tr><td><a href="#indvars">-indvars</a></td><td>Canonicalize Induction Variables</td></tr>
<tr><td><a href="#inline">-inline</a></td><td>Function Integration/Inlining</td></tr>
<tr><td><a href="#licm">-licm</a></td><td>Loop Invariant Code Motion</td></tr>
<tr><td><a href="#loop-extract">-loop-extract</a></td><td>Extract loops into new functions</td></tr>
<tr><td><a href="#loop-extract-single">-loop-extract-single</a></td><td>Extract at most one loop into a new function</td></tr>
+<tr><td><a href="#loop-index-split">-loop-index-split</a></td><td>Index Split Loops</td></tr>
<tr><td><a href="#loop-reduce">-loop-reduce</a></td><td>Loop Strength Reduction</td></tr>
-<tr><td><a href="#loop-unroll">-loop-unroll</a></td><td>Unroll Loops</td></tr>
-<tr><td><a href="#loop-unswitch">-loop-unswitch</a></td><td>Unswitch Loops</td></tr>
-<tr><td><a href="#loopsimplify">-loopsimplify</a></td><td>Canonicalize Natural Loops</td></tr>
-<tr><td><a href="#lower-packed">-lower-packed</a></td><td>Lower Packed Operations</td></tr>
+<tr><td><a href="#loop-rotate">-loop-rotate</a></td><td>Rotate Loops</td></tr>
+<tr><td><a href="#loop-unroll">-loop-unroll</a></td><td>Unroll loops</td></tr>
+<tr><td><a href="#loop-unswitch">-loop-unswitch</a></td><td>Unswitch loops</td></tr>
+<tr><td><a href="#loopsimplify">-loopsimplify</a></td><td>Canonicalize natural loops</td></tr>
+<tr><td><a href="#lower-packed">-lower-packed</a></td><td>lowers packed operations to operations on smaller packed datatypes</td></tr>
<tr><td><a href="#lowerallocs">-lowerallocs</a></td><td>Lower allocations from instructions to calls</td></tr>
<tr><td><a href="#lowergc">-lowergc</a></td><td>Lower GC intrinsics, for GCless code generators</td></tr>
-<tr><td><a href="#lowerinvoke">-lowerinvoke</a></td><td>Lower Invoke and Unwind</td></tr>
-<tr><td><a href="#lowerselect">-lowerselect</a></td><td>Lower Selects To Branches</td></tr>
+<tr><td><a href="#lowerinvoke">-lowerinvoke</a></td><td>Lower invoke and unwind, for unwindless code generators</td></tr>
+<tr><td><a href="#lowerselect">-lowerselect</a></td><td>Lower select instructions to branches</td></tr>
<tr><td><a href="#lowersetjmp">-lowersetjmp</a></td><td>Lower Set Jump</td></tr>
<tr><td><a href="#lowerswitch">-lowerswitch</a></td><td>Lower SwitchInst's to branches</td></tr>
<tr><td><a href="#mem2reg">-mem2reg</a></td><td>Promote Memory to Register</td></tr>
-<tr><td><a href="#mergereturn">-mergereturn</a></td><td>Unify Function Exit Nodes</td></tr>
+<tr><td><a href="#mergereturn">-mergereturn</a></td><td>Unify function exit nodes</td></tr>
<tr><td><a href="#predsimplify">-predsimplify</a></td><td>Predicate Simplifier</td></tr>
<tr><td><a href="#prune-eh">-prune-eh</a></td><td>Remove unused exception handling info</td></tr>
<tr><td><a href="#raiseallocs">-raiseallocs</a></td><td>Raise allocations from calls to instructions</td></tr>
-<tr><td><a href="#reassociate">-reassociate</a></td><td>Reassociate Expressions</td></tr>
-<tr><td><a href="#reg2mem">-reg2mem</a></td><td>Demote Values to Memory</td></tr>
+<tr><td><a href="#reassociate">-reassociate</a></td><td>Reassociate expressions</td></tr>
+<tr><td><a href="#reg2mem">-reg2mem</a></td><td>Demote all values to stack slots</td></tr>
<tr><td><a href="#scalarrepl">-scalarrepl</a></td><td>Scalar Replacement of Aggregates</td></tr>
<tr><td><a href="#sccp">-sccp</a></td><td>Sparse Conditional Constant Propagation</td></tr>
<tr><td><a href="#simplify-libcalls">-simplify-libcalls</a></td><td>Simplify well-known library calls</td></tr>
<tr><td><a href="#strip">-strip</a></td><td>Strip all symbols from a module</td></tr>
<tr><td><a href="#tailcallelim">-tailcallelim</a></td><td>Tail Call Elimination</td></tr>
<tr><td><a href="#tailduplicate">-tailduplicate</a></td><td>Tail Duplication</td></tr>
-<tr><th colspan="3"><b>UTILITY PASSES</b></th></tr>
-<tr><th>Option</th><th>Name</th><th>Directory</th></tr>
-<tr><td><a href="#deadarghaX0r">-deadarghaX0r</a></td><td>Dead Argument Hacking (BUGPOINT ONLY)</td></tr>
-<tr><td><a href="#extract-blocks">-extract-blocks</a></td><td>Extract Basic Blocks From Module (BUGPOINT ONLY)</td></tr>
+
+
+<tr><th colspan="2"><b>UTILITY PASSES</b></th></tr>
+<tr><th>Option</th><th>Name</th></tr>
+<tr><td><a href="#deadarghaX0r">-deadarghaX0r</a></td><td>Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)</td></tr>
+<tr><td><a href="#extract-blocks">-extract-blocks</a></td><td>Extract Basic Blocks From Module (for bugpoint use)</td></tr>
<tr><td><a href="#emitbitcode">-emitbitcode</a></td><td>Bitcode Writer</td></tr>
<tr><td><a href="#verify">-verify</a></td><td>Module Verifier</td></tr>
+<tr><td><a href="#view-cfg">-view-cfg</a></td><td>View CFG of function</td></tr>
+<tr><td><a href="#view-cfg-only">-view-cfg-only</a></td><td>View CFG of function (with no function bodies)</td></tr>
</table>
</div>
<a name="aa-eval">Exhaustive Alias Analysis Precision Evaluator</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>This is a simple N^2 alias analysis accuracy evaluator.
+ Basically, for each function in the program, it simply queries to see how the
+ alias analysis implementation answers alias queries between each pair of
+ pointers in the function.</p>
+
+ <p>This is inspired and adapted from code by: Naveen Neelakantam, Francesco
+ Spadini, and Wojciech Stryjewski.</p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="anders-aa">Andersen's Interprocedural Alias Analysis</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This is an implementation of Andersen's interprocedural alias
+ analysis
+ </p>
+
+ <p>
+ In pointer analysis terms, this is a subset-based, flow-insensitive,
+ field-sensitive, and context-insensitive algorithm pointer algorithm.
+ </p>
+
+ <p>
+ This algorithm is implemented as three stages:
+ </p>
+
+ <ol>
+ <li>Object identification.</li>
+ <li>Inclusion constraint identification.</li>
+ <li>Offline constraint graph optimization.</li>
+ <li>Inclusion constraint solving.</li>
+ </ol>
+
+ <p>
+ The object identification stage identifies all of the memory objects in the
+ program, which includes globals, heap allocated objects, and stack allocated
+ objects.
+ </p>
+
+ <p>
+ The inclusion constraint identification stage finds all inclusion constraints
+ in the program by scanning the program, looking for pointer assignments and
+ other statements that effect the points-to graph. For a statement like
+ <code><var>A</var> = <var>B</var></code>, this statement is processed to
+ indicate that <var>A</var> can point to anything that <var>B</var> can point
+ to. Constraints can handle copies, loads, and stores, and address taking.
+ </p>
+
+ <p>
+ The offline constraint graph optimization portion includes offline variable
+ substitution algorithms intended to computer pointer and location
+ equivalences. Pointer equivalences are those pointers that will have the
+ same points-to sets, and location equivalences are those variables that
+ always appear together in points-to sets.
+ </p>
+
+ <p>
+ The inclusion constraint solving phase iteratively propagates the inclusion
+ constraints until a fixed point is reached. This is an O(<var>n</var>³)
+ algorithm.
+ </p>
+
+ <p>
+ Function constraints are handled as if they were structs with <var>X</var>
+ fields. Thus, an access to argument <var>X</var> of function <var>Y</var> is
+ an access to node index <code>getNode(<var>Y</var>) + <var>X</var></code>.
+ This representation allows handling of indirect calls without any issues. To
+ wit, an indirect call <code><var>Y</var>(<var>a</var>,<var>b</var>)</code> is
+ equivalent to <code>*(<var>Y</var> + 1) = <var>a</var>, *(<var>Y</var> + 2) =
+ <var>b</var></code>. The return node for a function <var>F</var> is always
+ located at <code>getNode(<var>F</var>) + CallReturnPos</code>. The arguments
+ start at <code>getNode(<var>F</var>) + CallArgPos</code>.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="basicaa">Basic Alias Analysis</a>
+ <a name="basicaa">Basic Alias Analysis (default AA impl)</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This is the default implementation of the Alias Analysis interface
+ that simply implements a few identities (two different globals cannot alias,
+ etc), but otherwise does no analysis.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="basiccg">Basic Call Graph Construction</a>
+ <a name="basiccg">Basic CallGraph Construction</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="basicvn">Basic Value Numbering</a>
+ <a name="basicvn">Basic Value Numbering (default GVN impl)</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This is the default implementation of the <code>ValueNumbering</code>
+ interface. It walks the SSA def-use chains to trivially identify
+ lexically identical expressions. This does not require any ahead of time
+ analysis, so it is a very fast default implementation.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="callgraph">Print Call Graph</a>
+ <a name="callgraph">Print a call graph</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints the call graph to
+ standard output in a human-readable form.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="callscc">Print SCCs of the Call Graph</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints the SCCs of the call
+ graph to standard output in a human-readable form.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="cfgscc">Print SCCs of each Function Control Flow Graph</a>
+ <a name="cfgscc">Print SCCs of each function CFG</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints the SCCs of each
+ function CFG to standard output in a human-readable form.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="count-aa">Count Alias Analysis Query Responses</a>
+ <a name="codegenprepare">Optimize for code generation</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass munges the code in the input function to better prepare it for
+ SelectionDAG-based code generation. This works around limitations in it's
+ basic-block-at-a-time approach. It should eventually be removed.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="debug-aa">Alias Analysis Usage Debugger</a>
+ <a name="count-aa">Count Alias Analysis Query Responses</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ A pass which can be used to count how many alias queries
+ are being made and how the alias analysis implementation being used responds.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="domfrontier">Dominance Frontier Construction</a>
+ <a name="debug-aa">AA use debugger</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This simple pass checks alias analysis users to ensure that if they
+ create a new value, they do not query AA without informing it of the value.
+ It acts as a shim over any other AA pass you want.
+ </p>
+
+ <p>
+ Yes keeping track of every value in the program is expensive, but this is
+ a debugging pass.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="domset">Dominator Set Construction</a>
+ <a name="domfrontier">Dominance Frontier Construction</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is a simple dominator construction algorithm for finding forward
+ dominator frontiers.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="domtree">Dominator Tree Construction</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="etforest">ET Forest Construction</a>
-</div>
-<div class="doc_text">
- <p>Yet to be written.</p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="basicvn">Basic Value Numbering</a>
-</div>
-<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is a simple dominator construction algorithm for finding forward
+ dominators.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="externalfnconstants">Print external fn callsites passed constants</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints out call sites to
+ external functions that are called with constant arguments. This can be
+ useful when looking for standard library functions we should constant fold
+ or handle in alias analyses.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="globalsmodref-aa">Simple mod/ref analysis for globals</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="idom">Immediate Dominators Construction</a>
-</div>
-<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This simple pass provides alias and mod/ref information for global values
+ that do not have their address taken, and keeps track of whether functions
+ read or write memory (are "pure"). For this simple (but very common) case,
+ we can provide pretty accurate and useful information.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="instcount">Counts the various types of Instructions</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass collects the count of all instructions and reports them
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="intervals">Interval Partition Construction</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This analysis calculates and represents the interval partition of a function,
+ or a preexisting interval partition.
+ </p>
+
+ <p>
+ In this way, the interval partition may be used to reduce a flow graph down
+ to its degenerate single node interval partition (unless it is irreducible).
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="load-vn">Load Value Numbering</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass value numbers load and call instructions. To do this, it finds
+ lexically identical load instructions, and uses alias analysis to determine
+ which loads are guaranteed to produce the same value. To value number call
+ instructions, it looks for calls to functions that do not write to memory
+ which do not have intervening instructions that clobber the memory that is
+ read from.
+ </p>
+
+ <p>
+ This pass builds off of another value numbering pass to implement value
+ numbering for non-load and non-call instructions. It uses Alias Analysis so
+ that it can disambiguate the load instructions. The more powerful these base
+ analyses are, the more powerful the resultant value numbering will be.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="loops">Natural Loop Construction</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This analysis is used to identify natural loops and determine the loop depth
+ of various nodes of the CFG. Note that the loops identified may actually be
+ several natural loops that share the same header node... not just a single
+ natural loop.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="no-aa">No Alias Analysis (always returns 'may' alias)</a>
+ <a name="memdep">Memory Dependence Analysis</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ An analysis that determines, for a given memory operation, what preceding
+ memory operations it depends on. It builds on alias analysis information, and
+ tries to provide a lazy, caching interface to a common kind of alias
+ information query.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="no-profile">No Profile Information</a>
+ <a name="no-aa">No Alias Analysis (always returns 'may' alias)</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Always returns "I don't know" for alias queries. NoAA is unlike other alias
+ analysis implementations, in that it does not chain to a previous analysis. As
+ such it doesn't follow many of the rules that other alias analyses must.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="postdomfrontier">Post-Dominance Frontier Construction</a>
+ <a name="no-profile">No Profile Information</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ The default "no profile" implementation of the abstract
+ <code>ProfileInfo</code> interface.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="postdomset">Post-Dominator Set Construction</a>
+ <a name="postdomfrontier">Post-Dominance Frontier Construction</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is a simple post-dominator construction algorithm for finding
+ post-dominator frontiers.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="postdomtree">Post-Dominator Tree Construction</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="postetforest">Post-ET-Forest Construction</a>
-</div>
-<div class="doc_text">
- <p>Yet to be written.</p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="postidom">Immediate Post-Dominators Construction</a>
-</div>
-<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is a simple post-dominator construction algorithm for finding
+ post-dominators.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="print">Print function to stderr</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ The <code>PrintFunctionPass</code> class is designed to be pipelined with
+ other <code>FunctionPass</code>es, and prints out the functions of the module
+ as they are processed.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="print-callgraph">Print Call Graph to 'dot' file</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints the call graph into a
+ <code>.dot</code> graph. This graph can then be processed with the "dot" tool
+ to convert it to postscript or some other suitable format.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="print-cfg">Print CFG of function to 'dot' file</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints the control flow graph
+ into a <code>.dot</code> graph. This graph can then be processed with the
+ "dot" tool to convert it to postscript or some other suitable format.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="print-cfg-only">Print CFG of function to 'dot' file (with no function bodies)</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass, only available in <code>opt</code>, prints the control flow graph
+ into a <code>.dot</code> graph, omitting the function bodies. This graph can
+ then be processed with the "dot" tool to convert it to postscript or some
+ other suitable format.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="printm">Print module to stderr</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass simply prints out the entire module when it is executed.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="printusedtypes">Find Used Types</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is used to seek out all of the types in use by the program. Note
+ that this analysis explicitly does not include types only used by the symbol
+ table.
</div>
<!-------------------------------------------------------------------------- -->
<a name="profile-loader">Load profile information from llvmprof.out</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ A concrete implementation of profiling information that loads the information
+ from a profile dump file.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="scalar-evolution">Scalar Evolution Analysis</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ The <code>ScalarEvolution</code> analysis can be used to analyze and
+ catagorize scalar expressions in loops. It specializes in recognizing general
+ induction variables, representing them with the abstract and opaque
+ <code>SCEV</code> class. Given this analysis, trip counts of loops and other
+ important properties can be obtained.
+ </p>
+
+ <p>
+ This analysis is primarily useful for induction variable substitution and
+ strength reduction.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="targetdata">Target Data Layout</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>Provides other passes access to information on how the size and alignment
+ required by the the target ABI for various data types.</p>
</div>
<!-- ======================================================================= -->
<a name="argpromotion">Promote 'by reference' arguments to scalars</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass promotes "by reference" arguments to be "by value" arguments. In
+ practice, this means looking for internal functions that have pointer
+ arguments. If it can prove, through the use of alias analysis, that an
+ argument is *only* loaded, then it can pass the value into the function
+ instead of the address of the value. This can cause recursive simplification
+ of code and lead to the elimination of allocas (especially in C++ template
+ code like the STL).
+ </p>
+
+ <p>
+ This pass also handles aggregate arguments that are passed into a function,
+ scalarizing them if the elements of the aggregate are only loaded. Note that
+ it refuses to scalarize aggregates which would require passing in more than
+ three operands to the function, because passing thousands of operands for a
+ large array or structure is unprofitable!
+ </p>
+
+ <p>
+ Note that this transformation could also be done for arguments that are only
+ stored to (returning the value instead), but does not currently. This case
+ would be best handled when and if LLVM starts supporting multiple return
+ values from functions.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="block-placement">Profile Guided Basic Block Placement</a>
</div>
<div class="doc_text">
- <p>This pass implements a very simple profile guided basic block placement
- algorithm. The idea is to put frequently executed blocks together at the
- start of the function, and hopefully increase the number of fall-through
- conditional branches. If there is no profile information for a particular
- function, this pass basically orders blocks in depth-first order.</p>
- <p>The algorithm implemented here is basically "Algo1" from "Profile Guided
- Code Positioning" by Pettis and Hansen, except that it uses basic block
- counts instead of edge counts. This could be improved in many ways, but is
- very simple for now.</p>
- <p>Basically we "place" the entry block, then loop over all successors in a
- DFO, placing the most frequently executed successor until we run out of
- blocks. Did we mention that this was <b>extremely</b> simplistic? This is
- also much slower than it could be. When it becomes important, this pass
- will be rewritten to use a better algorithm, and then we can worry about
- efficiency.</p>
+ <p>This pass is a very simple profile guided basic block placement algorithm.
+ The idea is to put frequently executed blocks together at the start of the
+ function and hopefully increase the number of fall-through conditional
+ branches. If there is no profile information for a particular function, this
+ pass basically orders blocks in depth-first order.</p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="break-crit-edges">Break Critical Edges in CFG</a>
+ <a name="break-crit-edges">Break critical edges in CFG</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Break all of the critical edges in the CFG by inserting a dummy basic block.
+ It may be "required" by passes that cannot deal with critical edges. This
+ transformation obviously invalidates the CFG, but can update forward dominator
+ (set, immediate dominators, tree, and frontier) information.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<p>Correlated Expression Elimination propagates information from conditional
branches to blocks dominated by destinations of the branch. It propagates
information from the condition check itself into the body of the branch,
- allowing transformations like these for example:
- <pre>
- if (i == 7)
- ... 4*i; // constant propagation
+ allowing transformations like these for example:</p>
+
+<blockquote><pre>
+if (i == 7)
+ ... 4*i; // constant propagation
- M = i+1; N = j+1;
- if (i == j)
- X = M-N; // = M-M == 0;
- </pre></p>
+M = i+1; N = j+1;
+if (i == j)
+ X = M-N; // = M-M == 0;
+</pre></blockquote>
<p>This is called Correlated Expression Elimination because we eliminate or
simplify expressions that are correlated with the direction of a branch. In
<a name="constmerge">Merge Duplicate Global Constants</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Merges duplicate global constants together into a single constant that is
+ shared. This is useful because some passes (ie TraceValues) insert a lot of
+ string constants into the program, regardless of whether or not an existing
+ string is available.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="constprop">Constant Propagation</a>
+ <a name="constprop">Simple constant propagation</a>
</div>
<div class="doc_text">
<p>This file implements constant propagation and merging. It looks for
instructions involving only constant operands and replaces them with a
- constant value instead of an instruction. For example:
- <pre>add i32 1, 2</pre><br/>
- becomes
- <pre>i32 3</pre></p>
+ constant value instead of an instruction. For example:</p>
+ <blockquote><pre>add i32 1, 2</pre></blockquote>
+ <p>becomes</p>
+ <blockquote><pre>i32 3</pre></blockquote>
<p>NOTE: this pass has a habit of making definitions be dead. It is a good
idea to to run a <a href="#die">DIE</a> (Dead Instruction Elimination) pass
sometime after running this pass.</p>
<a name="dce">Dead Code Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Dead code elimination is similar to <a href="#die">dead instruction
+ elimination</a>, but it rechecks instructions that were used by removed
+ instructions to see if they are newly dead.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="deadargelim">Dead Argument Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass deletes dead arguments from internal functions. Dead argument
+ elimination removes arguments which are directly dead, as well as arguments
+ only passed into function calls as dead arguments of other functions. This
+ pass also deletes dead arguments in a similar way.
+ </p>
+
+ <p>
+ This pass is often useful as a cleanup pass to run after aggressive
+ interprocedural passes, which add possibly-dead arguments.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="deadtypeelim">Dead Type Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is used to cleanup the output of GCC. It eliminate names for types
+ that are unused in the entire translation unit, using the <a
+ href="#findusedtypes">find used types</a> pass.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="die">Dead Instruction Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Dead instruction elimination performs a single pass over the function,
+ removing instructions that are obviously dead.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="dse">Dead Store Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ A trivial dead store elimination that only considers basic-block local
+ redundant stores.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="gcse">Global Common Subexpression Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass is designed to be a very quick global transformation that
+ eliminates global common subexpressions from a function. It does this by
+ using an existing value numbering implementation to identify the common
+ subexpressions, eliminating them when possible.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="globaldce">Dead Global Elimination</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This transform is designed to eliminate unreachable internal globals from the
+ program. It uses an aggressive algorithm, searching out globals that are
+ known to be alive. After it finds all of the globals which are needed, it
+ deletes whatever is left over. This allows it to delete recursive chunks of
+ the program which are unreachable.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="globalopt">Global Variable Optimizer</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass transforms simple global variables that never have their address
+ taken. If obviously true, it marks read/write globals as constant, deletes
+ variables only stored to, etc.
+ </p>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<div class="doc_subsection">
+ <a name="gvn">Global Value Numbering</a>
+</div>
+<div class="doc_text">
+ <p>
+ This pass performs global value numbering to eliminate fully redundant
+ instructions. It also performs simple dead load elimination.
+ </p>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<div class="doc_subsection">
+ <a name="gvnpre">Global Value Numbering/Partial Redundancy Elimination</a>
+</div>
+<div class="doc_text">
+ <p>
+ This pass performs a hybrid of global value numbering and partial redundancy
+ elimination, known as GVN-PRE. It performs partial redundancy elimination on
+ values, rather than lexical expressions, allowing a more comprehensive view
+ the optimization. It replaces redundant values with uses of earlier
+ occurences of the same value. While this is beneficial in that it eliminates
+ unneeded computation, it also increases register pressure by creating large
+ live ranges, and should be used with caution on platforms that are very
+ sensitive to register pressure.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="indmemrem">Indirect Malloc and Free Removal</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass finds places where memory allocation functions may escape into
+ indirect land. Some transforms are much easier (aka possible) only if free
+ or malloc are not called indirectly.
+ </p>
+
+ <p>
+ Thus find places where the address of memory functions are taken and construct
+ bounce functions with direct calls of those functions.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="indvars">Canonicalize Induction Variables</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This transformation analyzes and transforms the induction variables (and
+ computations derived from them) into simpler forms suitable for subsequent
+ analysis and transformation.
+ </p>
+
+ <p>
+ This transformation makes the following changes to each loop with an
+ identifiable induction variable:
+ </p>
+
+ <ol>
+ <li>All loops are transformed to have a <em>single</em> canonical
+ induction variable which starts at zero and steps by one.</li>
+ <li>The canonical induction variable is guaranteed to be the first PHI node
+ in the loop header block.</li>
+ <li>Any pointer arithmetic recurrences are raised to use array
+ subscripts.</li>
+ </ol>
+
+ <p>
+ If the trip count of a loop is computable, this pass also makes the following
+ changes:
+ </p>
+
+ <ol>
+ <li>The exit condition for the loop is canonicalized to compare the
+ induction value against the exit value. This turns loops like:
+ <blockquote><pre>for (i = 7; i*i < 1000; ++i)</pre></blockquote>
+ into
+ <blockquote><pre>for (i = 0; i != 25; ++i)</pre></blockquote></li>
+ <li>Any use outside of the loop of an expression derived from the indvar
+ is changed to compute the derived value outside of the loop, eliminating
+ the dependence on the exit value of the induction variable. If the only
+ purpose of the loop is to compute the exit value of some derived
+ expression, this transformation will make the loop dead.</li>
+ </p>
+
+ <p>
+ This transformation should be followed by strength reduction after all of the
+ desired loop transformations have been performed. Additionally, on targets
+ where it is profitable, the loop could be transformed to count down to zero
+ (the "do loop" optimization).
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="inline">Function Integration/Inlining</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Bottom-up inlining of functions into callees.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="insert-block-profiling">Insert instrumentation for block profiling</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass instruments the specified program with counters for basic block
+ profiling, which counts the number of times each basic block executes. This
+ is the most basic form of profiling, which can tell which blocks are hot, but
+ cannot reliably detect hot paths through the CFG.
+ </p>
+
+ <p>
+ Note that this implementation is very naïve. Control equivalent regions of
+ the CFG should not require duplicate counters, but it does put duplicate
+ counters in.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="insert-edge-profiling">Insert instrumentation for edge profiling</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass instruments the specified program with counters for edge profiling.
+ Edge profiling can give a reasonable approximation of the hot paths through a
+ program, and is used for a wide variety of program transformations.
+ </p>
+
+ <p>
+ Note that this implementation is very naïve. It inserts a counter for
+ <em>every</em> edge in the program, instead of using control flow information
+ to prune the number of counters inserted.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="insert-function-profiling">Insert instrumentation for function profiling</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ This pass instruments the specified program with counters for function
+ profiling, which counts the number of times each function is called.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="insert-null-profiling-rs">Measure profiling framework overhead</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ The basic profiler that does nothing. It is the default profiler and thus
+ terminates <code>RSProfiler</code> chains. It is useful for measuring
+ framework overhead.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="insert-rs-profiling-framework">Insert random sampling instrumentation framework</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ The second stage of the random-sampling instrumentation framework, duplicates
+ all instructions in a function, ignoring the profiling code, then connects the
+ two versions together at the entry and at backedges. At each connection point
+ a choice is made as to whether to jump to the profiled code (take a sample) or
+ execute the unprofiled code.
+ </p>
+
+ <p>
+ After this pass, it is highly recommended to run<a href="#mem2reg">mem2reg</a>
+ and <a href="#adce">adce</a>. <a href="#instcombine">instcombine</a>,
+ <a href="#load-vn">load-vn</a>, <a href="#gdce">gdce</a>, and
+ <a href="#dse">dse</a> also are good to run afterwards.
+ </p>
</div>
<!-------------------------------------------------------------------------- -->
<a name="instcombine">Combine redundant instructions</a>
</div>
<div class="doc_text">
- <p>Yet to be written.</p>
+ <p>
+ Combine instructions to form fewer, simple
+ instructions. This pass does not modify the CFG This pass is where algebraic
+ simplification happens.
+ </p>
+
+ <p>
+ This pass combines things like:
+ </p>
+
+<blockquote><pre
+>%Y = add i32 %X, 1
+%Z = add i32 %Y, 1</pre></blockquote>
+
+ <p>
+ into:
+ </p>
+
+<blockquote><pre
+>%Z = add i32 %X, 2</pre></blockquote>
+
+ <p>
+ This is a simple worklist driven algorithm.
+ </p>
+
+ <p>
+ This pass guarantees that the following canonicalizations are performed on
+ the program:
+ </p>
+
+ <ul>
+ <li>If a binary operator has a constant operand, it is moved to the right-
+ hand side.</li>
+ <li>Bitwise operators with constant operands are always grouped so that
+ shifts are performed first, then <code>or</code>s, then
+ <code>and</code>s, then <code>xor</code>s.</li>
+ <li>Compare instructions are converted from <code><</code>,
+ <code>></code>, <code>≤</code>, or <code>≥</code> to
+ <code>=</code> or <code>≠</code> if possible.</li>
+ <li>All <code>cmp</code> instructions on boolean values are replaced with
+ logical operations.</li>
+ <li><code>add <var>X</var>, <var>X</var></code> is represented as
+ <code>mul <var>X</var>, 2</code> ⇒ <code>shl <var>X</var>, 1</code></li>
+ <li>Multiplies with a constant power-of-two argument are transformed into
+ shifts.</li>
+ <li>… etc.</li>
+ </ul>
</div>
<!-------------------------------------------------------------------------- -->
<p>Yet to be written.</p>
</div>
+<!-------------------------------------------------------------------------- -->
+<div class="doc_subsection">
+ <a name="loop-index-split">Index Split Loops</a>
+</div>
+<div class="doc_text">
+ <p>Yet to be written.</p>
+</div>
+
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
<a name="loop-reduce">Loop Strength Reduction</a>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="loop-unroll">Unroll Loops</a>
+ <a name="loop-rotate">Rotate Loops</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="loop-unswitch">Unswitch Loops</a>
+ <a name="loop-unroll">Unroll loops</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="loopsimplify">Canonicalize Natural Loops</a>
+ <a name="loop-unswitch">Unswitch loops</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="lower-packed">Lower Packed Operations</a>
+ <a name="loopsimplify">Canonicalize natural loops</a>
+</div>
+<div class="doc_text">
+ <p>Yet to be written.</p>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<div class="doc_subsection">
+ <a name="lower-packed">lowers packed operations to operations on smaller packed datatypes</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="lowerinvoke">Lower Invoke and Unwind</a>
+ <a name="lowerinvoke">Lower invoke and unwind, for unwindless code generators</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="lowerselect">Lower Selects To Branches</a>
+ <a name="lowerselect">Lower select instructions to branches</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="mergereturn">Unify Function Exit Nodes</a>
+ <a name="mergereturn">Unify function exit nodes</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="reassociate">Reassociate Expressions</a>
+ <a name="reassociate">Reassociate expressions</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="reg2mem">Demote Values to Memory</a>
+ <a name="reg2mem">Demote all values to stack slots</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="deadarghaX0r">Dead Argument Hacking (BUGPOINT ONLY)</a>
+ <a name="deadarghaX0r">Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<!-------------------------------------------------------------------------- -->
<div class="doc_subsection">
- <a name="extract-blocks">Extract Basic Blocks From Module (BUGPOINT ONLY)</a>
+ <a name="extract-blocks">Extract Basic Blocks From Module (for bugpoint use)</a>
</div>
<div class="doc_text">
<p>Yet to be written.</p>
<p>Yet to be written.</p>
</div>
+<!-------------------------------------------------------------------------- -->
+<div class="doc_subsection">
+ <a name="view-cfg">View CFG of function</a>
+</div>
+<div class="doc_text">
+ <p>Yet to be written.</p>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<div class="doc_subsection">
+ <a name="view-cfg-only">View CFG of function (with no function bodies)</a>
+</div>
+<div class="doc_text">
+ <p>Yet to be written.</p>
+</div>
+
<!-- *********************************************************************** -->
<hr>
projects / oota-llvm.git / blobdiff