</head>
<body>
-<div class="doc_title">
+<h1>
Writing an LLVM Pass
-</div>
+</h1>
<ol>
<li><a href="#introduction">Introduction - What is a pass?</a></li>
<li><a href="#doFinalization_loop">The <tt>doFinalization()
</tt> method</a></li>
</ul></li>
+ <li><a href="#RegionPass">The <tt>RegionPass</tt> class</a>
+ <ul>
+ <li><a href="#doInitialization_region">The <tt>doInitialization(Region *,
+ RGPassManager &)</tt> method</a></li>
+ <li><a href="#runOnRegion">The <tt>runOnRegion</tt> method</a></li>
+ <li><a href="#doFinalization_region">The <tt>doFinalization()
+ </tt> method</a></li>
+ </ul></li>
<li><a href="#BasicBlockPass">The <tt>BasicBlockPass</tt> class</a>
<ul>
<li><a href="#doInitialization_fn">The <tt>doInitialization(Function
<li><a href="#AU::addRequired">The <tt>AnalysisUsage::addRequired<></tt> and <tt>AnalysisUsage::addRequiredTransitive<></tt> methods</a></li>
<li><a href="#AU::addPreserved">The <tt>AnalysisUsage::addPreserved<></tt> method</a></li>
<li><a href="#AU::examples">Example implementations of <tt>getAnalysisUsage</tt></a></li>
- <li><a href="#getAnalysis">The <tt>getAnalysis<></tt> and <tt>getAnalysisToUpdate<></tt> methods</a></li>
+ <li><a href="#getAnalysis">The <tt>getAnalysis<></tt> and
+<tt>getAnalysisIfAvailable<></tt> methods</a></li>
</ul></li>
<li><a href="#analysisgroup">Implementing Analysis Groups</a>
<ul>
</div>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="introduction">Introduction - What is a pass?</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>The LLVM Pass Framework is an important part of the LLVM system, because LLVM
passes are where most of the interesting parts of the compiler exist. Passes
href="#CallGraphSCCPass">CallGraphSCCPass</a></tt>, <tt><a
href="#FunctionPass">FunctionPass</a></tt>, or <tt><a
href="#LoopPass">LoopPass</a></tt>, or <tt><a
+href="#RegionPass">RegionPass</a></tt>, or <tt><a
href="#BasicBlockPass">BasicBlockPass</a></tt> classes, which gives the system
more information about what your pass does, and how it can be combined with
other passes. One of the main features of the LLVM Pass Framework is that it
</div>
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="quickstart">Quick Start - Writing hello world</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>Here we describe how to write the "hello world" of passes. The "Hello" pass
is designed to simply print out the name of non-external functions that exist in
inspects it. The source code and files for this pass are available in the LLVM
source tree in the <tt>lib/Transforms/Hello</tt> directory.</p>
-</div>
-
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="makefile">Setting up the build environment</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
- <p>First, you need to create a new directory somewhere in the LLVM source
+ <p>First, configure and build LLVM. This needs to be done directly inside the
+ LLVM source tree rather than in a separate objects directory.
+ Next, you need to create a new directory somewhere in the LLVM source
base. For this example, we'll assume that you made
- <tt>lib/Transforms/Hello</tt>. Next, you must set up a build script
+ <tt>lib/Transforms/Hello</tt>. Finally, you must set up a build script
(Makefile) that will compile the source code for the new pass. To do this,
copy the following into <tt>Makefile</tt>:</p>
- <hr/>
+ <hr>
<div class="doc_code"><pre>
# Makefile for hello pass
-# Path to top level of LLVM heirarchy
+# Path to top level of LLVM hierarchy
LEVEL = ../../..
# Name of the library to build
# dlopen/dlsym on the resulting library.
LOADABLE_MODULE = 1
-# Tell the build system which LLVM libraries your pass needs. You'll probably
-# need at least LLVMSystem.a, LLVMSupport.a, LLVMCore.a but possibly several
-# others too.
-LLVMLIBS = LLVMCore.a LLVMSupport.a LLVMSystem.a
-
# Include the makefile implementation stuff
include $(LEVEL)/Makefile.common
</pre></div>
<p>This makefile specifies that all of the <tt>.cpp</tt> files in the current
-directory are to be compiled and linked together into a
-<tt>Debug/lib/Hello.so</tt> shared object that can be dynamically loaded by
+directory are to be compiled and linked together into a shared object
+<tt>$(LEVEL)/Debug+Asserts/lib/Hello.so</tt> that can be dynamically loaded by
the <tt>opt</tt> or <tt>bugpoint</tt> tools via their <tt>-load</tt> options.
If your operating system uses a suffix other than .so (such as windows or
Mac OS/X), the appropriate extension will be used.</p>
+<p>If you are used CMake to build LLVM, see
+<a href="CMake.html#passdev">Developing an LLVM pass with CMake</a>.</p>
+
<p>Now that we have the build scripts set up, we just need to write the code for
the pass itself.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="basiccode">Basic code required</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>Now that we have a way to compile our new pass, we just have to write it.
Start out with:</p>
-<div class="doc_code"><pre>
+<div class="doc_code">
+<pre>
<b>#include</b> "<a href="http://llvm.org/doxygen/Pass_8h-source.html">llvm/Pass.h</a>"
<b>#include</b> "<a href="http://llvm.org/doxygen/Function_8h-source.html">llvm/Function.h</a>"
-</pre></div>
+<b>#include</b> "<a href="http://llvm.org/doxygen/raw__ostream_8h.html">llvm/Support/raw_ostream.h</a>"
+</pre>
+</div>
<p>Which are needed because we are writing a <tt><a
-href="http://llvm.org/doxygen/classllvm_1_1Pass.html">Pass</a></tt>, and
+href="http://llvm.org/doxygen/classllvm_1_1Pass.html">Pass</a></tt>,
we are operating on <tt><a
-href="http://llvm.org/doxygen/classllvm_1_1Function.html">Function</a></tt>'s.</p>
+href="http://llvm.org/doxygen/classllvm_1_1Function.html">Function</a></tt>'s,
+and we will be doing some printing.</p>
<p>Next we have:</p>
-<div class="doc_code"><pre>
+
+<div class="doc_code">
+<pre>
<b>using namespace llvm;</b>
-</pre></div>
+</pre>
+</div>
+
<p>... which is required because the functions from the include files
-live in the llvm namespace.
-</p>
+live in the llvm namespace.</p>
<p>Next we have:</p>
-<div class="doc_code"><pre>
+<div class="doc_code">
+<pre>
<b>namespace</b> {
-</pre></div>
+</pre>
+</div>
<p>... which starts out an anonymous namespace. Anonymous namespaces are to C++
what the "<tt>static</tt>" keyword is to C (at global scope). It makes the
-things declared inside of the anonymous namespace only visible to the current
+things declared inside of the anonymous namespace visible only to the current
file. If you're not familiar with them, consult a decent C++ book for more
information.</p>
<p>Next, we declare our pass itself:</p>
-<div class="doc_code"><pre>
+<div class="doc_code">
+<pre>
<b>struct</b> Hello : <b>public</b> <a href="#FunctionPass">FunctionPass</a> {
-</pre></div><p>
+</pre>
+</div>
<p>This declares a "<tt>Hello</tt>" class that is a subclass of <tt><a
href="http://llvm.org/doxygen/classllvm_1_1FunctionPass.html">FunctionPass</a></tt>.
The different builtin pass subclasses are described in detail <a
href="#passtype">later</a>, but for now, know that <a
-href="#FunctionPass"><tt>FunctionPass</tt></a>'s operate a function at a
+href="#FunctionPass"><tt>FunctionPass</tt></a>'s operate on a function at a
time.</p>
-<div class="doc_code"><pre>
- static char ID;
- Hello() : FunctionPass((intptr_t)&ID) {}
-</pre></div><p>
+<div class="doc_code">
+<pre>
+ static char ID;
+ Hello() : FunctionPass(ID) {}
+</pre>
+</div>
-<p> This declares pass identifier used by LLVM to identify pass. This allows LLVM to
-avoid using expensive C++ runtime information.</p>
+<p>This declares pass identifier used by LLVM to identify pass. This allows LLVM
+to avoid using expensive C++ runtime information.</p>
-<div class="doc_code"><pre>
+<div class="doc_code">
+<pre>
<b>virtual bool</b> <a href="#runOnFunction">runOnFunction</a>(Function &F) {
- llvm::cerr << "<i>Hello: </i>" << F.getName() << "\n";
+ errs() << "<i>Hello: </i>";
+ errs().write_escaped(F.getName()) << "\n";
<b>return false</b>;
}
}; <i>// end of struct Hello</i>
-</pre></div>
+} <i>// end of anonymous namespace</i>
+</pre>
+</div>
<p>We declare a "<a href="#runOnFunction"><tt>runOnFunction</tt></a>" method,
which overloads an abstract virtual method inherited from <a
to do our thing, so we just print out our message with the name of each
function.</p>
-<div class="doc_code"><pre>
- char Hello::ID = 0;
-</pre></div>
+<div class="doc_code">
+<pre>
+char Hello::ID = 0;
+</pre>
+</div>
-<p> We initialize pass ID here. LLVM uses ID's address to identify pass so
+<p>We initialize pass ID here. LLVM uses ID's address to identify a pass, so
initialization value is not important.</p>
-<div class="doc_code"><pre>
- RegisterPass<Hello> X("<i>hello</i>", "<i>Hello World Pass</i>",
- false /* Only looks at CFG */,
- false /* Analysis Pass */);
-} <i>// end of anonymous namespace</i>
-</pre></div>
+<div class="doc_code">
+<pre>
+static RegisterPass<Hello> X("<i>hello</i>", "<i>Hello World Pass</i>",
+ false /* Only looks at CFG */,
+ false /* Analysis Pass */);
+</pre>
+</div>
-<p>Lastly, we <a href="#registration">register our class</a> <tt>Hello</tt>,
-giving it a command line
-argument "<tt>hello</tt>", and a name "<tt>Hello World Pass</tt>".
-Last two RegisterPass arguments are optional. Their default value is false.
-If a pass walks CFG without modifying it then third argument is set to true.
-If a pass is an analysis pass, for example dominator tree pass, then true
-is supplied as fourth argument. </p>
+<p>Lastly, we <a href="#registration">register our class</a> <tt>Hello</tt>,
+giving it a command line argument "<tt>hello</tt>", and a name "<tt>Hello World
+Pass</tt>". The last two arguments describe its behavior: if a pass walks CFG
+without modifying it then the third argument is set to <tt>true</tt>; if a pass
+is an analysis pass, for example dominator tree pass, then <tt>true</tt> is
+supplied as the fourth argument.</p>
<p>As a whole, the <tt>.cpp</tt> file looks like:</p>
-<div class="doc_code"><pre>
+<div class="doc_code">
+<pre>
<b>#include</b> "<a href="http://llvm.org/doxygen/Pass_8h-source.html">llvm/Pass.h</a>"
<b>#include</b> "<a href="http://llvm.org/doxygen/Function_8h-source.html">llvm/Function.h</a>"
+<b>#include</b> "<a href="http://llvm.org/doxygen/raw__ostream_8h.html">llvm/Support/raw_ostream.h</a>"
<b>using namespace llvm;</b>
<b>struct Hello</b> : <b>public</b> <a href="#FunctionPass">FunctionPass</a> {
static char ID;
- Hello() : FunctionPass((intptr_t)&ID) {}
+ Hello() : FunctionPass(ID) {}
<b>virtual bool</b> <a href="#runOnFunction">runOnFunction</a>(Function &F) {
- llvm::cerr << "<i>Hello: </i>" << F.getName() << "\n";
+ errs() << "<i>Hello: </i>";
+ errs().write_escaped(F.getName()) << '\n';
<b>return false</b>;
}
+
};
-
- char Hello::ID = 0;
- RegisterPass<Hello> X("<i>hello</i>", "<i>Hello World Pass</i>");
}
-</pre></div>
+
+char Hello::ID = 0;
+static RegisterPass<Hello> X("hello", "Hello World Pass", false, false);
+</pre>
+</div>
<p>Now that it's all together, compile the file with a simple "<tt>gmake</tt>"
-command in the local directory and you should get a new
-"<tt>Debug/lib/Hello.so</tt> file. Note that everything in this file is
-contained in an anonymous namespace: this reflects the fact that passes are self
-contained units that do not need external interfaces (although they can have
-them) to be useful.</p>
+command in the local directory and you should get a new file
+"<tt>Debug+Asserts/lib/Hello.so</tt>" under the top level directory of the LLVM
+source tree (not in the local directory). Note that everything in this file is
+contained in an anonymous namespace — this reflects the fact that passes
+are self contained units that do not need external interfaces (although they can
+have them) to be useful.</p>
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="running">Running a pass with <tt>opt</tt></a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>Now that you have a brand new shiny shared object file, we can use the
<tt>opt</tt> command to run an LLVM program through your pass. Because you
-registered your pass with the <tt>RegisterPass</tt> template, you will be able to
+registered your pass with <tt>RegisterPass</tt>, you will be able to
use the <tt>opt</tt> tool to access it, once loaded.</p>
<p>To test it, follow the example at the end of the <a
work):</p>
<div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -hello < hello.bc > /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -hello < hello.bc > /dev/null
Hello: __main
Hello: puts
Hello: main
<tt>/dev/null</tt>).</p>
<p>To see what happened to the other string you registered, try running
-<tt>opt</tt> with the <tt>--help</tt> option:</p>
+<tt>opt</tt> with the <tt>-help</tt> option:</p>
<div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so --help
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -help
OVERVIEW: llvm .bc -> .bc modular optimizer
USAGE: opt [options] <input bitcode>
example:</p>
<div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -hello -time-passes < hello.bc > /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -hello -time-passes < hello.bc > /dev/null
Hello: __main
Hello: puts
Hello: main
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="passtype">Pass classes and requirements</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>One of the first things that you should do when designing a new pass is to
decide what class you should subclass for your pass. The <a
<p>When choosing a superclass for your Pass, you should choose the <b>most
specific</b> class possible, while still being able to meet the requirements
listed. This gives the LLVM Pass Infrastructure information necessary to
-optimize how passes are run, so that the resultant compiler isn't unneccesarily
+optimize how passes are run, so that the resultant compiler isn't unnecessarily
slow.</p>
-</div>
-
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ImmutablePass">The <tt>ImmutablePass</tt> class</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>The most plain and boring type of pass is the "<tt><a
href="http://llvm.org/doxygen/classllvm_1_1ImmutablePass.html">ImmutablePass</a></tt>"
</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="ModulePass">The <tt>ModulePass</tt> class</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>The "<tt><a
href="http://llvm.org/doxygen/classllvm_1_1ModulePass.html">ModulePass</a></tt>"
class is the most general of all superclasses that you can use. Deriving from
<tt>ModulePass</tt> indicates that your pass uses the entire program as a unit,
-refering to function bodies in no predictable order, or adding and removing
+referring to function bodies in no predictable order, or adding and removing
functions. Because nothing is known about the behavior of <tt>ModulePass</tt>
-subclasses, no optimization can be done for their execution. A module pass
-can use function level passes (e.g. dominators) using getAnalysis interface
-<tt> getAnalysis<DominatorTree>(Function)</tt>. </p>
+subclasses, no optimization can be done for their execution.</p>
+
+<p>A module pass can use function level passes (e.g. dominators) using
+the getAnalysis interface
+<tt>getAnalysis<DominatorTree>(llvm::Function *)</tt> to provide the
+function to retrieve analysis result for, if the function pass does not require
+any module or immutable passes. Note that this can only be done for functions for which the
+analysis ran, e.g. in the case of dominators you should only ask for the
+DominatorTree for function definitions, not declarations.</p>
<p>To write a correct <tt>ModulePass</tt> subclass, derive from
<tt>ModulePass</tt> and overload the <tt>runOnModule</tt> method with the
following signature:</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="runOnModule">The <tt>runOnModule</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> runOnModule(Module &M) = 0;
</div>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="CallGraphSCCPass">The <tt>CallGraphSCCPass</tt> class</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>The "<tt><a
href="http://llvm.org/doxygen/classllvm_1_1CallGraphSCCPass.html">CallGraphSCCPass</a></tt>"
<ol>
-<li>... <em>not allowed</em> to modify any <tt>Function</tt>s that are not in
-the current SCC.</li>
-
-<li>... <em>not allowed</em> to inspect any Function's other than those in the
-current SCC and the direct callees of the SCC.</li>
+<li>... <em>not allowed</em> to inspect or modify any <tt>Function</tt>s other
+than those in the current SCC and the direct callers and direct callees of the
+SCC.</li>
<li>... <em>required</em> to preserve the current CallGraph object, updating it
to reflect any changes made to the program.</li>
methods described below should return true if they modified the program, or
false if they didn't.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doInitialization_scc">The <tt>doInitialization(CallGraph &)</tt>
- method</a>
-</div>
+<h4>
+ <a name="doInitialization_scc">
+ The <tt>doInitialization(CallGraph &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doInitialization(CallGraph &CG);
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="runOnSCC">The <tt>runOnSCC</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
- <b>virtual bool</b> runOnSCC(const std::vector<CallGraphNode *> &SCCM) = 0;
+ <b>virtual bool</b> runOnSCC(CallGraphSCC &SCC) = 0;
</pre></div>
<p>The <tt>runOnSCC</tt> method performs the interesting work of the pass, and
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doFinalization_scc">The <tt>doFinalization(CallGraph
- &)</tt> method</a>
-</div>
+<h4>
+ <a name="doFinalization_scc">
+ The <tt>doFinalization(CallGraph &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doFinalization(CallGraph &CG);
</div>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="FunctionPass">The <tt>FunctionPass</tt> class</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>In contrast to <tt>ModulePass</tt> subclasses, <tt><a
href="http://llvm.org/doxygen/classllvm_1_1Pass.html">FunctionPass</a></tt>
may overload three virtual methods to do their work. All of these methods
should return true if they modified the program, or false if they didn't.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doInitialization_mod">The <tt>doInitialization(Module &)</tt>
- method</a>
-</div>
+<h4>
+ <a name="doInitialization_mod">
+ The <tt>doInitialization(Module &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doInitialization(Module &M);
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="runOnFunction">The <tt>runOnFunction</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> runOnFunction(Function &F) = 0;
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doFinalization_mod">The <tt>doFinalization(Module
- &)</tt> method</a>
-</div>
+<h4>
+ <a name="doFinalization_mod">
+ The <tt>doFinalization(Module &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doFinalization(Module &M);
</div>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="LoopPass">The <tt>LoopPass</tt> class </a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p> All <tt>LoopPass</tt> execute on each loop in the function independent of
all of the other loops in the function. <tt>LoopPass</tt> processes loops in
<p> <tt>LoopPass</tt> subclasses are allowed to update loop nest using
<tt>LPPassManager</tt> interface. Implementing a loop pass is usually
-straightforward. <tt>Looppass</tt>'s may overload three virtual methods to
+straightforward. <tt>LoopPass</tt>'s may overload three virtual methods to
do their work. All these methods should return true if they modified the
program, or false if they didn't. </p>
-</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doInitialization_loop">The <tt>doInitialization(Loop *,
- LPPassManager &)</tt>
- method</a>
-</div>
+<h4>
+ <a name="doInitialization_loop">
+ The <tt>doInitialization(Loop *,LPPassManager &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doInitialization(Loop *, LPPassManager &LPM);
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="runOnLoop">The <tt>runOnLoop</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> runOnLoop(Loop *, LPPassManager &LPM) = 0;
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="doFinalization_loop">The <tt>doFinalization()</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doFinalization();
</div>
+</div>
+<!-- ======================================================================= -->
+<h3>
+ <a name="RegionPass">The <tt>RegionPass</tt> class </a>
+</h3>
+
+<div>
+
+<p> <tt>RegionPass</tt> is similar to <a href="#LoopPass"><tt>LoopPass</tt></a>,
+but executes on each single entry single exit region in the function.
+<tt>RegionPass</tt> processes regions in nested order such that the outer most
+region is processed last. </p>
+
+<p> <tt>RegionPass</tt> subclasses are allowed to update the region tree by using
+the <tt>RGPassManager</tt> interface. You may overload three virtual methods of
+<tt>RegionPass</tt> to implement your own region pass. All these
+methods should return true if they modified the program, or false if they didn not.
+</p>
+
+<!-- _______________________________________________________________________ -->
+<h4>
+ <a name="doInitialization_region">
+ The <tt>doInitialization(Region *, RGPassManager &)</tt> method
+ </a>
+</h4>
+
+<div>
+
+<div class="doc_code"><pre>
+ <b>virtual bool</b> doInitialization(Region *, RGPassManager &RGM);
+</pre></div>
+
+<p>The <tt>doInitialization</tt> method is designed to do simple initialization
+type of stuff that does not depend on the functions being processed. The
+<tt>doInitialization</tt> method call is not scheduled to overlap with any
+other pass executions (thus it should be very fast). RPPassManager
+interface should be used to access Function or Module level analysis
+information.</p>
+
+</div>
+
+
+<!-- _______________________________________________________________________ -->
+<h4>
+ <a name="runOnRegion">The <tt>runOnRegion</tt> method</a>
+</h4>
+
+<div>
+
+<div class="doc_code"><pre>
+ <b>virtual bool</b> runOnRegion(Region *, RGPassManager &RGM) = 0;
+</pre></div><p>
+
+<p>The <tt>runOnRegion</tt> method must be implemented by your subclass to do
+the transformation or analysis work of your pass. As usual, a true value should
+be returned if the region is modified. <tt>RGPassManager</tt> interface
+should be used to update region tree.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<h4>
+ <a name="doFinalization_region">The <tt>doFinalization()</tt> method</a>
+</h4>
+
+<div>
+
+<div class="doc_code"><pre>
+ <b>virtual bool</b> doFinalization();
+</pre></div>
+
+<p>The <tt>doFinalization</tt> method is an infrequently used method that is
+called when the pass framework has finished calling <a
+href="#runOnRegion"><tt>runOnRegion</tt></a> for every region in the
+program being compiled. </p>
+
+</div>
+
+</div>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="BasicBlockPass">The <tt>BasicBlockPass</tt> class</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p><tt>BasicBlockPass</tt>'s are just like <a
href="#FunctionPass"><tt>FunctionPass</tt></a>'s, except that they must limit
href="#doFinalization_mod"><tt>doFinalization(Module &)</tt></a> methods that <a
href="#FunctionPass"><tt>FunctionPass</tt></a>'s have, but also have the following virtual methods that may also be implemented:</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doInitialization_fn">The <tt>doInitialization(Function
- &)</tt> method</a>
-</div>
+<h4>
+ <a name="doInitialization_fn">
+ The <tt>doInitialization(Function &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doInitialization(Function &F);
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="runOnBasicBlock">The <tt>runOnBasicBlock</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> runOnBasicBlock(BasicBlock &BB) = 0;
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="doFinalization_fn">The <tt>doFinalization(Function &)</tt>
- method</a>
-</div>
+<h4>
+ <a name="doFinalization_fn">
+ The <tt>doFinalization(Function &)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> doFinalization(Function &F);
</div>
+</div>
+
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<h3>
<a name="MachineFunctionPass">The <tt>MachineFunctionPass</tt> class</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>A <tt>MachineFunctionPass</tt> is a part of the LLVM code generator that
executes on the machine-dependent representation of each LLVM function in the
-program. A <tt>MachineFunctionPass</tt> is also a <tt>FunctionPass</tt>, so all
+program.</p>
+
+<p>Code generator passes are registered and initialized specially by
+<tt>TargetMachine::addPassesToEmitFile</tt> and similar routines, so they
+cannot generally be run from the <tt>opt</tt> or <tt>bugpoint</tt>
+commands.</p>
+
+<p>A <tt>MachineFunctionPass</tt> is also a <tt>FunctionPass</tt>, so all
the restrictions that apply to a <tt>FunctionPass</tt> also apply to it.
<tt>MachineFunctionPass</tt>es also have additional restrictions. In particular,
<tt>MachineFunctionPass</tt>es are not allowed to do any of the following:</p>
<ol>
-<li>Modify any LLVM Instructions, BasicBlocks or Functions.</li>
+<li>Modify or create any LLVM IR Instructions, BasicBlocks, Arguments,
+ Functions, GlobalVariables, GlobalAliases, or Modules.</li>
<li>Modify a MachineFunction other than the one currently being processed.</li>
-<li>Add or remove MachineFunctions from the current Module.</li>
-<li>Add or remove global variables from the current Module.</li>
<li>Maintain state across invocations of <a
href="#runOnMachineFunction"><tt>runOnMachineFunction</tt></a> (including global
data)</li>
</ol>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="runOnMachineFunction">The <tt>runOnMachineFunction(MachineFunction
- &MF)</tt> method</a>
-</div>
+<h4>
+ <a name="runOnMachineFunction">
+ The <tt>runOnMachineFunction(MachineFunction &MF)</tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual bool</b> runOnMachineFunction(MachineFunction &MF) = 0;
</div>
+</div>
+
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="registration">Pass registration</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>In the <a href="#basiccode">Hello World</a> example pass we illustrated how
pass registration works, and discussed some of the reasons that it is used and
what it does. Here we discuss how and why passes are registered.</p>
<p>As we saw above, passes are registered with the <b><tt>RegisterPass</tt></b>
-template, which requires you to pass at least two
-parameters. The first parameter is the name of the pass that is to be used on
+template. The template parameter is the name of the pass that is to be used on
the command line to specify that the pass should be added to a program (for
-example, with <tt>opt</tt> or <tt>bugpoint</tt>). The second argument is the
-name of the pass, which is to be used for the <tt>--help</tt> output of
+example, with <tt>opt</tt> or <tt>bugpoint</tt>). The first argument is the
+name of the pass, which is to be used for the <tt>-help</tt> output of
programs, as
well as for debug output generated by the <tt>--debug-pass</tt> option.</p>
<p>If you want your pass to be easily dumpable, you should
implement the virtual <tt>print</tt> method:</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="print">The <tt>print</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
- <b>virtual void</b> print(llvm::OStream &O, <b>const</b> Module *M) <b>const</b>;
+ <b>virtual void</b> print(std::ostream &O, <b>const</b> Module *M) <b>const</b>;
</pre></div>
<p>The <tt>print</tt> method must be implemented by "analyses" in order to print
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="interaction">Specifying interactions between passes</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>One of the main responsibilities of the <tt>PassManager</tt> is to make sure
that passes interact with each other correctly. Because <tt>PassManager</tt>
href="#getAnalysisUsage">getAnalysisUsage</a></tt> method, it defaults to not
having any prerequisite passes, and invalidating <b>all</b> other passes.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="getAnalysisUsage">The <tt>getAnalysisUsage</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual void</b> getAnalysisUsage(AnalysisUsage &Info) <b>const</b>;
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="AU::addRequired">The <tt>AnalysisUsage::addRequired<></tt> and <tt>AnalysisUsage::addRequiredTransitive<></tt> methods</a>
-</div>
-
-<div class="doc_text">
+<h4>
+ <a name="AU::addRequired">
+ The <tt>AnalysisUsage::addRequired<></tt>
+ and <tt>AnalysisUsage::addRequiredTransitive<></tt> methods
+ </a>
+</h4>
+
+<div>
<p>
If your pass requires a previous pass to be executed (an analysis for example),
it can use one of these methods to arrange for it to be run before your pass.
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="AU::addPreserved">The <tt>AnalysisUsage::addPreserved<></tt> method</a>
-</div>
+<h4>
+ <a name="AU::addPreserved">
+ The <tt>AnalysisUsage::addPreserved<></tt> method
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<p>
One of the jobs of the PassManager is to optimize how and when analyses are run.
In particular, it attempts to avoid recomputing data unless it needs to. For
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="AU::examples">Example implementations of <tt>getAnalysisUsage</tt></a>
-</div>
+<h4>
+ <a name="AU::examples">
+ Example implementations of <tt>getAnalysisUsage</tt>
+ </a>
+</h4>
-<div class="doc_text">
-
-<div class="doc_code"><pre>
- <i>// This is an example implementation from an analysis, which does not modify
- // the program at all, yet has a prerequisite.</i>
- <b>void</b> <a href="http://llvm.org/doxygen/classllvm_1_1PostDominanceFrontier.html">PostDominanceFrontier</a>::getAnalysisUsage(AnalysisUsage &AU) <b>const</b> {
- AU.setPreservesAll();
- AU.addRequired<<a href="http://llvm.org/doxygen/classllvm_1_1PostDominatorTree.html">PostDominatorTree</a>>();
- }
-</pre></div>
-
-<p>and:</p>
+<div>
<div class="doc_code"><pre>
<i>// This example modifies the program, but does not modify the CFG</i>
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="getAnalysis">The <tt>getAnalysis<></tt> and <tt>getAnalysisToUpdate<></tt> methods</a>
-</div>
+<h4>
+ <a name="getAnalysis">
+ The <tt>getAnalysis<></tt> and
+ <tt>getAnalysisIfAvailable<></tt> methods
+ </a>
+</h4>
-<div class="doc_text">
+<div>
<p>The <tt>Pass::getAnalysis<></tt> method is automatically inherited by
your class, providing you with access to the passes that you declared that you
<p>
If your pass is capable of updating analyses if they exist (e.g.,
<tt>BreakCriticalEdges</tt>, as described above), you can use the
-<tt>getAnalysisToUpdate</tt> method, which returns a pointer to the analysis if
-it is active. For example:</p>
+<tt>getAnalysisIfAvailable</tt> method, which returns a pointer to the analysis
+if it is active. For example:</p>
<div class="doc_code"><pre>
...
- if (DominatorSet *DS = getAnalysisToUpdate<DominatorSet>()) {
+ if (DominatorSet *DS = getAnalysisIfAvailable<DominatorSet>()) {
<i>// A DominatorSet is active. This code will update it.</i>
}
...
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="analysisgroup">Implementing Analysis Groups</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>Now that we understand the basics of how passes are defined, how they are
used, and how they are required from other passes, it's time to get a little bit
situations like this, the LLVM Pass Infrastructure supports the notion of
Analysis Groups.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="agconcepts">Analysis Group Concepts</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>An Analysis Group is a single simple interface that may be implemented by
multiple different passes. Analysis Groups can be given human readable names
<p>Although <a href="#registration">Pass Registration</a> is optional for normal
passes, all analysis group implementations must be registered, and must use the
-<A href="#registerag"><tt>RegisterAnalysisGroup</tt></a> template to join the
+<A href="#registerag"><tt>INITIALIZE_AG_PASS</tt></a> template to join the
implementation pool. Also, a default implementation of the interface
<b>must</b> be registered with <A
href="#registerag"><tt>RegisterAnalysisGroup</tt></a>.</p>
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="registerag">Using <tt>RegisterAnalysisGroup</tt></a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>The <tt>RegisterAnalysisGroup</tt> template is used to register the analysis
-group itself as well as add pass implementations to the analysis group. First,
-an analysis should be registered, with a human readable name provided for it.
+group itself, while the <tt>INITIALIZE_AG_PASS</tt> is used to add pass
+implementations to the analysis group. First,
+an analysis group should be registered, with a human readable name
+provided for it.
Unlike registration of passes, there is no command line argument to be specified
for the Analysis Group Interface itself, because it is "abstract":</p>
<div class="doc_code"><pre>
<b>namespace</b> {
- //<i> Analysis Group implementations <b>must</b> be registered normally...</i>
- RegisterPass<FancyAA>
- B("<i>somefancyaa</i>", "<i>A more complex alias analysis implementation</i>");
-
//<i> Declare that we implement the AliasAnalysis interface</i>
- RegisterAnalysisGroup<<a href="http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html">AliasAnalysis</a>> C(B);
+ INITIALIZE_AG_PASS(FancyAA, <a href="http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html">AliasAnalysis</a>, "<i>somefancyaa</i>",
+ "<i>A more complex alias analysis implementation</i>",
+ false, // <i>Is CFG Only?</i>
+ true, // <i>Is Analysis?</i>
+ false, // <i>Is default Analysis Group implementation?</i>
+ );
}
</pre></div>
-<p>This just shows a class <tt>FancyAA</tt> that is registered normally, then
-uses the <tt>RegisterAnalysisGroup</tt> template to "join" the <tt><a
-href="http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html">AliasAnalysis</a></tt>
+<p>This just shows a class <tt>FancyAA</tt> that
+uses the <tt>INITIALIZE_AG_PASS</tt> macro both to register and
+to "join" the <tt><a href="http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html">AliasAnalysis</a></tt>
analysis group. Every implementation of an analysis group should join using
-this template. A single pass may join multiple different analysis groups with
-no problem.</p>
+this macro.</p>
<div class="doc_code"><pre>
<b>namespace</b> {
- //<i> Analysis Group implementations <b>must</b> be registered normally...</i>
- RegisterPass<<a href="http://llvm.org/doxygen/structBasicAliasAnalysis.html">BasicAliasAnalysis</a>>
- D("<i>basicaa</i>", "<i>Basic Alias Analysis (default AA impl)</i>");
-
//<i> Declare that we implement the AliasAnalysis interface</i>
- RegisterAnalysisGroup<<a href="http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html">AliasAnalysis</a>, <b>true</b>> E(D);
+ INITIALIZE_AG_PASS(BasicAA, <a href="http://llvm.org/doxygen/classllvm_1_1AliasAnalysis.html">AliasAnalysis</a>, "<i>basicaa</i>",
+ "<i>Basic Alias Analysis (default AA impl)</i>",
+ false, // <i>Is CFG Only?</i>
+ true, // <i>Is Analysis?</i>
+ true, // <i>Is default Analysis Group implementation?</i>
+ );
}
</pre></div>
-<p>Here we show how the default implementation is specified (using the extra
-argument to the <tt>RegisterAnalysisGroup</tt> template). There must be exactly
+<p>Here we show how the default implementation is specified (using the final
+argument to the <tt>INITIALIZE_AG_PASS</tt> template). There must be exactly
one default implementation available at all times for an Analysis Group to be
used. Only default implementation can derive from <tt>ImmutablePass</tt>.
Here we declare that the
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="passStatistics">Pass Statistics</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>The <a
href="http://llvm.org/doxygen/Statistic_8h-source.html"><tt>Statistic</tt></a>
class is designed to be an easy way to expose various success
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="passmanager">What PassManager does</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>The <a
href="http://llvm.org/doxygen/PassManager_8h-source.html"><tt>PassManager</tt></a>
<li><b>Pipeline the execution of passes on the program</b> - The
<tt>PassManager</tt> attempts to get better cache and memory usage behavior out
of a series of passes by pipelining the passes together. This means that, given
-a series of conse
qutive <a href="#FunctionPass"><tt>FunctionPass</tt></a>'s, it
+a series of conse
cutive <a href="#FunctionPass"><tt>FunctionPass</tt></a>'s, it
will execute all of the <a href="#FunctionPass"><tt>FunctionPass</tt></a>'s on
the first function, then all of the <a
href="#FunctionPass"><tt>FunctionPass</tt></a>es on the second function,
options that is useful for debugging pass execution, seeing how things work, and
diagnosing when you should be preserving more analyses than you currently are
(To get information about all of the variants of the <tt>--debug-pass</tt>
-option, just type '<tt>opt --help-hidden</tt>').</p>
+option, just type '<tt>opt -help-hidden</tt>').</p>
<p>By using the <tt>--debug-pass=Structure</tt> option, for example, we can see
how our <a href="#basiccode">Hello World</a> pass interacts with other passes.
Lets try it out with the <tt>gcse</tt> and <tt>licm</tt> passes:</p>
<div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -gcse -licm --debug-pass=Structure < hello.bc > /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -gcse -licm --debug-pass=Structure < hello.bc > /dev/null
Module Pass Manager
Function Pass Manager
Dominator Set Construction
World</a> pass in between the two passes:</p>
<div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -gcse -hello -licm --debug-pass=Structure < hello.bc > /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -gcse -hello -licm --debug-pass=Structure < hello.bc > /dev/null
Module Pass Manager
Function Pass Manager
Dominator Set Construction
<p>Now when we run our pass, we get this output:</p>
<div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -gcse -hello -licm --debug-pass=Structure < hello.bc > /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -gcse -hello -licm --debug-pass=Structure < hello.bc > /dev/null
Pass Arguments: -gcse -hello -licm
Module Pass Manager
Function Pass Manager
<p>Which shows that we don't accidentally invalidate dominator information
anymore, and therefore do not have to compute it twice.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="releaseMemory">The <tt>releaseMemory</tt> method</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<div class="doc_code"><pre>
<b>virtual void</b> releaseMemory();
<p>If you are writing an analysis or any other pass that retains a significant
amount of state (for use by another pass which "requires" your pass and uses the
<a href="#getAnalysis">getAnalysis</a> method) you should implement
-<tt>releaseMEmory</tt> to, well, release the memory allocated to maintain this
+<tt>releaseMemory</tt> to, well, release the memory allocated to maintain this
internal state. This method is called after the <tt>run*</tt> method for the
class, before the next call of <tt>run*</tt> in your pass.</p>
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="registering">Registering dynamically loaded passes</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p><i>Size matters</i> when constructing production quality tools using llvm,
both for the purposes of distribution, and for regulating the resident code size
in the tool will be registered at start up. A dynamically loaded pass will
register on load and unregister at unload.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsection">
+<h3>
<a name="registering_existing">Using existing registries</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>There are predefined registries to track instruction scheduling
(<tt>RegisterScheduler</tt>) and register allocation (<tt>RegisterRegAlloc</tt>)
</pre></div>
<p>Note the two spaces prior to the help string produces a tidy result on the
---help query.</p>
+-help query.</p>
<div class="doc_code"><pre>
-$ llc --help
+$ llc -help
...
- -regalloc - Register allocator to use: (default = linearscan)
+ -regalloc - Register allocator to use (default=linearscan)
=linearscan - linear scan register allocator
=local - local register allocator
=simple - simple register allocator
<!-- _______________________________________________________________________ -->
-<div class="doc_subsection">
+<h3>
<a name="registering_new">Creating new registries</a>
-</div>
+</h3>
-<div class="doc_text">
+<div>
<p>The easiest way to get started is to clone one of the existing registries; we
recommend <tt>llvm/CodeGen/RegAllocRegistry.h</tt>. The key things to modify
<div class="doc_code"><pre>
cl::opt<RegisterMyPasses::FunctionPassCtor, false,
- RegisterPassParser<RegisterMyPasses> >
+ RegisterPassParser<RegisterMyPasses> >
MyPassOpt("mypass",
cl::init(&createDefaultMyPass),
cl::desc("my pass option help"));
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="debughints">Using GDB with dynamically loaded passes</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>Unfortunately, using GDB with dynamically loaded passes is not as easy as it
should be. First of all, you can't set a breakpoint in a shared object that has
transformation invoked by <tt>opt</tt>, although nothing described here depends
on that.</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="breakpoint">Setting a breakpoint in your pass</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>First thing you do is start <tt>gdb</tt> on the <tt>opt</tt> process:</p>
<div class="doc_code"><pre>
(gdb) <b>break llvm::PassManager::run</b>
Breakpoint 1 at 0x2413bc: file Pass.cpp, line 70.
-(gdb) <b>run test.bc -load $(LLVMTOP)/llvm/Debug/lib/[libname].so -[passoption]</b>
-Starting program: opt test.bc -load $(LLVMTOP)/llvm/Debug/lib/[libname].so -[passoption]
+(gdb) <b>run test.bc -load $(LLVMTOP)/llvm/Debug+Asserts/lib/[libname].so -[passoption]</b>
+Starting program: opt test.bc -load $(LLVMTOP)/llvm/Debug+Asserts/lib/[libname].so -[passoption]
Breakpoint 1, PassManager::run (this=0xffbef174, M=@0x70b298) at Pass.cpp:70
70 bool PassManager::run(Module &M) { return PM->run(M); }
(gdb)
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="debugmisc">Miscellaneous Problems</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>Once you have the basics down, there are a couple of problems that GDB has,
some with solutions, some without.</p>
</div>
+</div>
+
<!-- *********************************************************************** -->
-<div class="doc_section">
+<h2>
<a name="future">Future extensions planned</a>
-</div>
+</h2>
<!-- *********************************************************************** -->
-<div class="doc_text">
+<div>
<p>Although the LLVM Pass Infrastructure is very capable as it stands, and does
some nifty stuff, there are things we'd like to add in the future. Here is
where we are going:</p>
-</div>
-
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
+<h4>
<a name="SMP">Multithreaded LLVM</a>
-</div>
+</h4>
-<div class="doc_text">
+<div>
<p>Multiple CPU machines are becoming more common and compilation can never be
fast enough: obviously we should allow for a multithreaded compiler. Because of
</div>
+</div>
+
<!-- *********************************************************************** -->
<hr>
<address>
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
- src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
+ src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
<a href="http://validator.w3.org/check/referer"><img
- src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
+ src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
- <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
+ <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
</address>
projects / oota-llvm.git / blobdiff