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<title>LLVM's Analysis and Transform Passes</title>
- <link rel="stylesheet" href="llvm.css" type="text/css">
+ <link rel="stylesheet" href="_static/llvm.css" type="text/css">
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-<div class="doc_title">LLVM's Analysis and Transform Passes</div>
+<h1>LLVM's Analysis and Transform Passes</h1>
<ol>
<li><a href="#intro">Introduction</a></li>
</div>
<!-- ======================================================================= -->
-<div class="doc_section"> <a name="intro">Introduction</a> </div>
-<div class="doc_text">
+<h2><a name="intro">Introduction</a></h2>
+<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.
bitcode are neither analysis nor transform passes.
<p>The table below provides a quick summary of each pass and links to the more
complete pass description later in the document.</p>
-</div>
-<div class="doc_text" >
+
<table>
<tr><th colspan="2"><b>ANALYSIS 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="#always-inline">-always-inline</a></td><td>Inliner for always_inline functions</td></tr>
<tr><td><a href="#argpromotion">-argpromotion</a></td><td>Promote 'by reference' arguments to scalars</td></tr>
+<tr><td><a href="#bb-vectorize">-bb-vectorize</a></td><td>Combine instructions to form vector instructions within basic blocks</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="#codegenprepare">-codegenprepare</a></td><td>Optimize for code generation</td></tr>
<tr><td><a href="#loop-unswitch">-loop-unswitch</a></td><td>Unswitch loops</td></tr>
<tr><td><a href="#loweratomic">-loweratomic</a></td><td>Lower atomic intrinsics to non-atomic form</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="#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="#memcpyopt">-memcpyopt</a></td><td>MemCpy Optimization</td></tr>
<tr><td><a href="#view-postdom">-view-postdom</a></td><td>View postdominance tree of function</td></tr>
<tr><td><a href="#view-postdom-only">-view-postdom-only</a></td><td>View postdominance tree of function (with no function bodies)</td></tr>
</table>
+
</div>
<!-- ======================================================================= -->
-<div class="doc_section"> <a name="example">Analysis Passes</a></div>
-<div class="doc_text">
+<h2><a name="analyses">Analysis Passes</a></h2>
+<div>
<p>This section describes the LLVM Analysis Passes.</p>
-</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="aa-eval">-aa-eval: Exhaustive Alias Analysis Precision Evaluator</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="basicaa">-basicaa: Basic Alias Analysis (stateless AA impl)</a>
-</div>
-<div class="doc_text">
- <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>
+</h3>
+<div>
+ <p>A basic alias analysis pass that implements identities (two different
+ globals cannot alias, etc), but does no stateful analysis.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="basiccg">-basiccg: Basic CallGraph Construction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Yet to be written.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="count-aa">-count-aa: Count Alias Analysis Query Responses</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="debug-aa">-debug-aa: AA use debugger</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="domfrontier">-domfrontier: Dominance Frontier Construction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass is a simple dominator construction algorithm for finding forward
dominator frontiers.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="domtree">-domtree: Dominator Tree Construction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass is a simple dominator construction algorithm for finding forward
dominators.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-callgraph">-dot-callgraph: Print Call Graph to 'dot' file</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-cfg">-dot-cfg: Print CFG of function to 'dot' file</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-cfg-only">-dot-cfg-only: Print CFG of function to 'dot' file (with no function bodies)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-dom">-dot-dom: Print dominance tree of function to 'dot' file</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the dominator tree
into a <code>.dot</code> graph. This graph can then be processed with the
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-dom-only">-dot-dom-only: Print dominance tree of function to 'dot' file (with no function bodies)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the dominator tree
into a <code>.dot</code> graph, omitting the function bodies. This graph can
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-postdom">-dot-postdom: Print postdominance tree of function to 'dot' file</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the post dominator tree
into a <code>.dot</code> graph. This graph can then be processed with the
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dot-postdom-only">-dot-postdom-only: Print postdominance tree of function to 'dot' file (with no function bodies)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the post dominator tree
into a <code>.dot</code> graph, omitting the function bodies. This graph can
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="globalsmodref-aa">-globalsmodref-aa: Simple mod/ref analysis for globals</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="instcount">-instcount: Counts the various types of Instructions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass collects the count of all instructions and reports them
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="intervals">-intervals: Interval Partition Construction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This analysis calculates and represents the interval partition of a function,
or a preexisting interval partition.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="iv-users">-iv-users: Induction Variable Users</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Bookkeeping for "interesting" users of expressions computed from
induction variables.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="lazy-value-info">-lazy-value-info: Lazy Value Information Analysis</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Interface for lazy computation of value constraint information.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="lda">-lda: Loop Dependence Analysis</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Loop dependence analysis framework, which is used to detect dependences in
memory accesses in loops.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="libcall-aa">-libcall-aa: LibCall Alias Analysis</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>LibCall Alias Analysis.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="lint">-lint: Statically lint-checks LLVM IR</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This pass statically checks for common and easily-identified constructs
which produce undefined or likely unintended behavior in LLVM IR.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loops">-loops: Natural Loop Information</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="memdep">-memdep: Memory Dependence Analysis</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
An analysis that determines, for a given memory operation, what preceding
memory operations it depends on. It builds on alias analysis information, and
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="module-debuginfo">-module-debuginfo: Decodes module-level debug info</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This pass decodes the debug info metadata in a module and prints in a
(sufficiently-prepared-) human-readable form.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="no-aa">-no-aa: No Alias Analysis (always returns 'may' alias)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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.
+ This is the default implementation of the Alias Analysis interface. It 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">
+<h3>
<a name="no-profile">-no-profile: No Profile Information</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
The default "no profile" implementation of the abstract
<code>ProfileInfo</code> interface.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="postdomfrontier">-postdomfrontier: Post-Dominance Frontier Construction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass is a simple post-dominator construction algorithm for finding
post-dominator frontiers.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="postdomtree">-postdomtree: Post-Dominator Tree Construction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass is a simple post-dominator construction algorithm for finding
post-dominators.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-alias-sets">-print-alias-sets: Alias Set Printer</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Yet to be written.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-callgraph">-print-callgraph: Print a call graph</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the call graph to
standard error in a human-readable form.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-callgraph-sccs">-print-callgraph-sccs: Print SCCs of the Call Graph</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the SCCs of the call
graph to standard error in a human-readable form.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-cfg-sccs">-print-cfg-sccs: Print SCCs of each function CFG</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass, only available in <code>opt</code>, prints the SCCs of each
function CFG to standard error in a human-readable form.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-dbginfo">-print-dbginfo: Print debug info in human readable form</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Pass that prints instructions, and associated debug info:</p>
<ul>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-dom-info">-print-dom-info: Dominator Info Printer</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Dominator Info Printer.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-externalfnconstants">-print-externalfnconstants: Print external fn callsites passed constants</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-function">-print-function: Print function to stderr</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-module">-print-module: Print module to stderr</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass simply prints out the entire module when it is executed.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="print-used-types">-print-used-types: Find Used Types</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="profile-estimator">-profile-estimator: Estimate profiling information</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Profiling information that estimates the profiling information
in a very crude and unimaginative way.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="profile-loader">-profile-loader: Load profile information from llvmprof.out</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
A concrete implementation of profiling information that loads the information
from a profile dump file.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="profile-verifier">-profile-verifier: Verify profiling information</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Pass that checks profiling information for plausibility.</p>
</div>
-<div class="doc_subsection">
+<h3>
<a name="regions">-regions: Detect single entry single exit regions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
The <code>RegionInfo</code> pass detects single entry single exit regions in a
function, where a region is defined as any subgraph that is connected to the
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="scalar-evolution">-scalar-evolution: Scalar Evolution Analysis</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
The <code>ScalarEvolution</code> analysis can be used to analyze and
catagorize scalar expressions in loops. It specializes in recognizing general
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="scev-aa">-scev-aa: ScalarEvolution-based Alias Analysis</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>Simple alias analysis implemented in terms of ScalarEvolution queries.
This differs from traditional loop dependence analysis in that it tests
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="strip-dead-debug-info">-strip-dead-debug-info: Strip debug info for unused symbols</a>
-</div>
-<div class="doc_text">
- <p>
- performs code stripping. this transformation can delete:
- </p>
-
- <ol>
- <li>names for virtual registers</li>
- <li>symbols for internal globals and functions</li>
- <li>debug information</li>
- </ol>
-
- <p>
- note that this transformation makes code much less readable, so it should
- only be used in situations where the <tt>strip</tt> utility would be used,
- such as reducing code size or making it harder to reverse engineer code.
- </p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="targetdata">-targetdata: Target Data Layout</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_section"> <a name="transform">Transform Passes</a></div>
-<div class="doc_text">
+<h2><a name="transforms">Transform Passes</a></h2>
+<div>
<p>This section describes the LLVM Transform Passes.</p>
-</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="adce">-adce: Aggressive Dead Code Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>ADCE aggressively tries to eliminate code. This pass is similar to
<a href="#dce">DCE</a> but it assumes that values are dead until proven
otherwise. This is similar to <a href="#sccp">SCCP</a>, except applied to
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="always-inline">-always-inline: Inliner for always_inline functions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>A custom inliner that handles only functions that are marked as
"always inline".</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="argpromotion">-argpromotion: Promote 'by reference' arguments to scalars</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass promotes "by reference" arguments to be "by value" arguments. In
practice, this means looking for internal functions that have pointer
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="block-placement">-block-placement: Profile Guided Basic Block Placement</a>
+<h3>
+ <a name="bb-vectorize">-bb-vectorize: Basic-Block Vectorization</a>
+</h3>
+<div>
+ <p>This pass combines instructions inside basic blocks to form vector
+ instructions. It iterates over each basic block, attempting to pair
+ compatible instructions, repeating this process until no additional
+ pairs are selected for vectorization. When the outputs of some pair
+ of compatible instructions are used as inputs by some other pair of
+ compatible instructions, those pairs are part of a potential
+ vectorization chain. Instruction pairs are only fused into vector
+ instructions when they are part of a chain longer than some
+ threshold length. Moreover, the pass attempts to find the best
+ possible chain for each pair of compatible instructions. These
+ heuristics are intended to prevent vectorization in cases where
+ it would not yield a performance increase of the resulting code.
+ </p>
</div>
-<div class="doc_text">
+
+<!-------------------------------------------------------------------------- -->
+<h3>
+ <a name="block-placement">-block-placement: Profile Guided Basic Block Placement</a>
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="break-crit-edges">-break-crit-edges: Break critical edges in CFG</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="codegenprepare">-codegenprepare: Optimize for code generation</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
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.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="constmerge">-constmerge: Merge Duplicate Global Constants</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="constprop">-constprop: Simple constant propagation</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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:</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dce">-dce: Dead Code Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Dead code elimination is similar to <a href="#die">dead instruction
elimination</a>, but it rechecks instructions that were used by removed
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="deadargelim">-deadargelim: Dead Argument Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass deletes dead arguments from internal functions. Dead argument
elimination removes arguments which are directly dead, as well as arguments
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="deadtypeelim">-deadtypeelim: Dead Type Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="die">-die: Dead Instruction Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Dead instruction elimination performs a single pass over the function,
removing instructions that are obviously dead.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="dse">-dse: Dead Store Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
A trivial dead store elimination that only considers basic-block local
redundant stores.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="functionattrs">-functionattrs: Deduce function attributes</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>A simple interprocedural pass which walks the call-graph, looking for
functions which do not access or only read non-local memory, and marking them
readnone/readonly. In addition, it marks function arguments (of pointer type)
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="globaldce">-globaldce: Dead Global Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This transform is designed to eliminate unreachable internal globals from the
program. It uses an aggressive algorithm, searching out globals that are
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="globalopt">-globalopt: Global Variable Optimizer</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass transforms simple global variables that never have their address
taken. If obviously true, it marks read/write globals as constant, deletes
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="gvn">-gvn: Global Value Numbering</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass performs global value numbering to eliminate fully and partially
redundant instructions. It also performs redundant load elimination.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="indvars">-indvars: Canonicalize Induction Variables</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This transformation analyzes and transforms the induction variables (and
computations derived from them) into simpler forms suitable for subsequent
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="inline">-inline: Function Integration/Inlining</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Bottom-up inlining of functions into callees.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="insert-edge-profiling">-insert-edge-profiling: Insert instrumentation for edge profiling</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="insert-optimal-edge-profiling">-insert-optimal-edge-profiling: Insert optimal instrumentation for edge profiling</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<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.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="instcombine">-instcombine: Combine redundant instructions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Combine instructions to form fewer, simple
instructions. This pass does not modify the CFG This pass is where algebraic
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="internalize">-internalize: Internalize Global Symbols</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass loops over all of the functions in the input module, looking for a
main function. If a main function is found, all other functions and all
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="ipconstprop">-ipconstprop: Interprocedural constant propagation</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass implements an <em>extremely</em> simple interprocedural constant
propagation pass. It could certainly be improved in many different ways,
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="ipsccp">-ipsccp: Interprocedural Sparse Conditional Constant Propagation</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
An interprocedural variant of <a href="#sccp">Sparse Conditional Constant
Propagation</a>.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="jump-threading">-jump-threading: Jump Threading</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Jump threading tries to find distinct threads of control flow running through
a basic block. This pass looks at blocks that have multiple predecessors and
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="lcssa">-lcssa: Loop-Closed SSA Form Pass</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass transforms loops by placing phi nodes at the end of the loops for
all values that are live across the loop boundary. For example, it turns
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="licm">-licm: Loop Invariant Code Motion</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass performs loop invariant code motion, attempting to remove as much
code from the body of a loop as possible. It does this by either hoisting
variable.</li>
</ul>
</div>
+
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loop-deletion">-loop-deletion: Delete dead loops</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This file implements the Dead Loop Deletion Pass. This pass is responsible
for eliminating loops with non-infinite computable trip counts that have no
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loop-extract">-loop-extract: Extract loops into new functions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
A pass wrapper around the <code>ExtractLoop()</code> scalar transformation to
extract each top-level loop into its own new function. If the loop is the
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loop-extract-single">-loop-extract-single: Extract at most one loop into a new function</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Similar to <a href="#loop-extract">Extract loops into new functions</a>,
this pass extracts one natural loop from the program into a function if it
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loop-reduce">-loop-reduce: Loop Strength Reduction</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass performs a strength reduction on array references inside loops that
have as one or more of their components the loop induction variable. This is
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loop-rotate">-loop-rotate: Rotate Loops</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>A simple loop rotation transformation.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="loop-unroll">-loop-unroll: Unroll loops</a>
-</div>
-<div class="doc_text">
- <p>
- This pass implements a simple loop unroller. It works best when loops have
- been canonicalized by the <a href="#indvars"><tt>-indvars</tt></a> pass,
- allowing it to determine the trip counts of loops easily.
- </p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="loop-unswitch">-loop-unswitch: Unswitch loops</a>
-</div>
-<div class="doc_text">
- <p>
- This pass transforms loops that contain branches on loop-invariant conditions
- to have multiple loops. For example, it turns the left into the right code:
- </p>
-
- <pre
->for (...) if (lic)
- A for (...)
- if (lic) A; B; C
- B else
- C for (...)
- A; C</pre>
-
- <p>
- This can increase the size of the code exponentially (doubling it every time
- a loop is unswitched) so we only unswitch if the resultant code will be
- smaller than a threshold.
- </p>
-
- <p>
- This pass expects LICM to be run before it to hoist invariant conditions out
- of the loop, to make the unswitching opportunity obvious.
- </p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="loop-simplify">-loop-simplify: Canonicalize natural loops</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass performs several transformations to transform natural loops into a
simpler form, which makes subsequent analyses and transformations simpler and
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="loweratomic">-loweratomic: Lower atomic intrinsics to non-atomic form</a>
+<h3>
+ <a name="loop-unroll">-loop-unroll: Unroll loops</a>
+</h3>
+<div>
+ <p>
+ This pass implements a simple loop unroller. It works best when loops have
+ been canonicalized by the <a href="#indvars"><tt>-indvars</tt></a> pass,
+ allowing it to determine the trip counts of loops easily.
+ </p>
</div>
-<div class="doc_text">
+
+<!-------------------------------------------------------------------------- -->
+<h3>
+ <a name="loop-unswitch">-loop-unswitch: Unswitch loops</a>
+</h3>
+<div>
+ <p>
+ This pass transforms loops that contain branches on loop-invariant conditions
+ to have multiple loops. For example, it turns the left into the right code:
+ </p>
+
+ <pre
+>for (...) if (lic)
+ A for (...)
+ if (lic) A; B; C
+ B else
+ C for (...)
+ A; C</pre>
+
+ <p>
+ This can increase the size of the code exponentially (doubling it every time
+ a loop is unswitched) so we only unswitch if the resultant code will be
+ smaller than a threshold.
+ </p>
+
+ <p>
+ This pass expects LICM to be run before it to hoist invariant conditions out
+ of the loop, to make the unswitching opportunity obvious.
+ </p>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<h3>
+ <a name="loweratomic">-loweratomic: Lower atomic intrinsics to non-atomic form</a>
+</h3>
+<div>
<p>
This pass lowers atomic intrinsics to non-atomic form for use in a known
non-preemptible environment.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="lowerinvoke">-lowerinvoke: Lower invoke and unwind, for unwindless code generators</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This transformation is designed for use by code generators which do not yet
support stack unwinding. This pass supports two models of exception handling
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="lowersetjmp">-lowersetjmp: Lower Set Jump</a>
-</div>
-<div class="doc_text">
- <p>
- Lowers <tt>setjmp</tt> and <tt>longjmp</tt> to use the LLVM invoke and unwind
- instructions as necessary.
- </p>
-
- <p>
- Lowering of <tt>longjmp</tt> is fairly trivial. We replace the call with a
- call to the LLVM library function <tt>__llvm_sjljeh_throw_longjmp()</tt>.
- This unwinds the stack for us calling all of the destructors for
- objects allocated on the stack.
- </p>
-
- <p>
- At a <tt>setjmp</tt> call, the basic block is split and the <tt>setjmp</tt>
- removed. The calls in a function that have a <tt>setjmp</tt> are converted to
- invoke where the except part checks to see if it's a <tt>longjmp</tt>
- exception and, if so, if it's handled in the function. If it is, then it gets
- the value returned by the <tt>longjmp</tt> and goes to where the basic block
- was split. <tt>invoke</tt> instructions are handled in a similar fashion with
- the original except block being executed if it isn't a <tt>longjmp</tt>
- except that is handled by that function.
- </p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="lowerswitch">-lowerswitch: Lower SwitchInst's to branches</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Rewrites <tt>switch</tt> instructions with a sequence of branches, which
allows targets to get away with not implementing the switch instruction until
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="mem2reg">-mem2reg: Promote Memory to Register</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This file promotes memory references to be register references. It promotes
<tt>alloca</tt> instructions which only have <tt>load</tt>s and
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="memcpyopt">-memcpyopt: MemCpy Optimization</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass performs various transformations related to eliminating memcpy
calls, or transforming sets of stores into memset's.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="mergefunc">-mergefunc: Merge Functions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This pass looks for equivalent functions that are mergable and folds them.
A hash is computed from the function, based on its type and number of
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="mergereturn">-mergereturn: Unify function exit nodes</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Ensure that functions have at most one <tt>ret</tt> instruction in them.
Additionally, it keeps track of which node is the new exit node of the CFG.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="partial-inliner">-partial-inliner: Partial Inliner</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This pass performs partial inlining, typically by inlining an if
statement that surrounds the body of the function.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="prune-eh">-prune-eh: Remove unused exception handling info</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This file implements a simple interprocedural pass which walks the call-graph,
turning <tt>invoke</tt> instructions into <tt>call</tt> instructions if and
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="reassociate">-reassociate: Reassociate expressions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass reassociates commutative expressions in an order that is designed
to promote better constant propagation, GCSE, LICM, PRE, etc.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="reg2mem">-reg2mem: Demote all values to stack slots</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This file demotes all registers to memory references. It is intented to be
the inverse of <a href="#mem2reg"><tt>-mem2reg</tt></a>. By converting to
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="scalarrepl">-scalarrepl: Scalar Replacement of Aggregates (DT)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
The well-known scalar replacement of aggregates transformation. This
transform breaks up <tt>alloca</tt> instructions of aggregate type (structure
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="sccp">-sccp: Sparse Conditional Constant Propagation</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Sparse conditional constant propagation and merging, which can be summarized
as:
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="sink">-sink: Code Sinking</a>
-</div>
-<div class="doc_text">
- <p>This pass moves instructions into successor blocks, when possible, so that
- they aren't executed on paths where their results aren't needed.
- </p>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="simplify-libcalls">-simplify-libcalls: Simplify well-known library calls</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Applies a variety of small optimizations for calls to specific well-known
function calls (e.g. runtime library functions). For example, a call
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="simplifycfg">-simplifycfg: Simplify the CFG</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Performs dead code elimination and basic block merging. Specifically:
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
+ <a name="sink">-sink: Code sinking</a>
+</h3>
+<div>
+ <p>This pass moves instructions into successor blocks, when possible, so that
+ they aren't executed on paths where their results aren't needed.
+ </p>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<h3>
+ <a name="sretpromotion">-sretpromotion: Promote sret arguments to multiple ret values</a>
+</h3>
+<div>
+ <p>
+ This pass finds functions that return a struct (using a pointer to the struct
+ as the first argument of the function, marked with the '<tt>sret</tt>' attribute) and
+ replaces them with a new function that simply returns each of the elements of
+ that struct (using multiple return values).
+ </p>
+
+ <p>
+ This pass works under a number of conditions:
+ </p>
+
+ <ul>
+ <li>The returned struct must not contain other structs</li>
+ <li>The returned struct must only be used to load values from</li>
+ <li>The placeholder struct passed in is the result of an <tt>alloca</tt></li>
+ </ul>
+</div>
+
+<!-------------------------------------------------------------------------- -->
+<h3>
<a name="strip">-strip: Strip all symbols from a module</a>
+</h3>
+<div>
+ <p>
+ performs code stripping. this transformation can delete:
+ </p>
+
+ <ol>
+ <li>names for virtual registers</li>
+ <li>symbols for internal globals and functions</li>
+ <li>debug information</li>
+ </ol>
+
+ <p>
+ note that this transformation makes code much less readable, so it should
+ only be used in situations where the <tt>strip</tt> utility would be used,
+ such as reducing code size or making it harder to reverse engineer code.
+ </p>
</div>
-<div class="doc_text">
+
+<!-------------------------------------------------------------------------- -->
+<h3>
+ <a name="strip-dead-debug-info">-strip-dead-debug-info: Strip debug info for unused symbols</a>
+</h3>
+<div>
<p>
performs code stripping. this transformation can delete:
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="strip-dead-prototypes">-strip-dead-prototypes: Strip Unused Function Prototypes</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass loops over all of the functions in the input module, looking for
dead declarations and removes them. Dead declarations are declarations of
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="strip-debug-declare">-strip-debug-declare: Strip all llvm.dbg.declare intrinsics</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This pass implements code stripping. Specifically, it can delete:</p>
<ul>
<li>names for virtual registers</li>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="strip-nondebug">-strip-nondebug: Strip all symbols, except dbg symbols, from a module</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This pass implements code stripping. Specifically, it can delete:</p>
<ul>
<li>names for virtual registers</li>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="sretpromotion">-sretpromotion: Promote sret arguments</a>
-</div>
-<div class="doc_text">
- <p>
- This pass finds functions that return a struct (using a pointer to the struct
- as the first argument of the function, marked with the '<tt>sret</tt>' attribute) and
- replaces them with a new function that simply returns each of the elements of
- that struct (using multiple return values).
- </p>
-
- <p>
- This pass works under a number of conditions:
- </p>
-
- <ul>
- <li>The returned struct must not contain other structs</li>
- <li>The returned struct must only be used to load values from</li>
- <li>The placeholder struct passed in is the result of an <tt>alloca</tt></li>
- </ul>
-</div>
-
-<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="tailcallelim">-tailcallelim: Tail Call Elimination</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This file transforms calls of the current function (self recursion) followed
by a return instruction with a branch to the entry of the function, creating
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="tailduplicate">-tailduplicate: Tail Duplication</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass performs a limited form of tail duplication, intended to simplify
CFGs by removing some unconditional branches. This pass is necessary to
</p>
</div>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_section"> <a name="transform">Utility Passes</a></div>
-<div class="doc_text">
+<h2><a name="utilities">Utility Passes</a></h2>
+<div>
<p>This section describes the LLVM Utility Passes.</p>
-</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="deadarghaX0r">-deadarghaX0r: Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Same as dead argument elimination, but deletes arguments to functions which
are external. This is only for use by <a
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="extract-blocks">-extract-blocks: Extract Basic Blocks From Module (for bugpoint use)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
This pass is used by bugpoint to extract all blocks from the module into their
own functions.</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="instnamer">-instnamer: Assign names to anonymous instructions</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>This is a little utility pass that gives instructions names, this is mostly
useful when diffing the effect of an optimization because deleting an
unnamed instruction can change all other instruction numbering, making the
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="preverify">-preverify: Preliminary module verification</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Ensures that the module is in the form required by the <a
href="#verifier">Module Verifier</a> pass.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="verify">-verify: Module Verifier</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Verifies an LLVM IR code. This is useful to run after an optimization which is
undergoing testing. Note that <tt>llvm-as</tt> verifies its input before
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="view-cfg">-view-cfg: View CFG of function</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Displays the control flow graph using the GraphViz tool.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="view-cfg-only">-view-cfg-only: View CFG of function (with no function bodies)</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Displays the control flow graph using the GraphViz tool, but omitting function
bodies.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="view-dom">-view-dom: View dominance tree of function</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Displays the dominator tree using the GraphViz tool.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="view-dom-only">-view-dom-only: View dominance tree of function (with no function
- bodies)
- </a>
-</div>
-<div class="doc_text">
+<h3>
+ <a name="view-dom-only">-view-dom-only: View dominance tree of function (with no function bodies)</a>
+</h3>
+<div>
<p>
Displays the dominator tree using the GraphViz tool, but omitting function
bodies.
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
+<h3>
<a name="view-postdom">-view-postdom: View postdominance tree of function</a>
-</div>
-<div class="doc_text">
+</h3>
+<div>
<p>
Displays the post dominator tree using the GraphViz tool.
</p>
</div>
<!-------------------------------------------------------------------------- -->
-<div class="doc_subsection">
- <a name="view-postdom-only">-view-postdom-only: View postdominance tree of function (with no
- function bodies)
- </a>
-</div>
-<div class="doc_text">
+<h3>
+ <a name="view-postdom-only">-view-postdom-only: View postdominance tree of function (with no function bodies)</a>
+</h3>
+<div>
<p>
Displays the post dominator tree using the GraphViz tool, but omitting
function bodies.
</p>
</div>
+</div>
+
<!-- *********************************************************************** -->
<hr>
src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
<a href="mailto:rspencer@x10sys.com">Reid Spencer</a><br>
- <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org/">LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
</address>
projects / oota-llvm.git / blobdiff