X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FWritingAnLLVMPass.html;h=ed985cdc98f896161ce7b2e6f19a2be99d48a72a;hb=9c3d5e41b94ff51dc78ae42397151b52d9c2b546;hp=c967000a9e08ea86a0681d27f5a3d80d229c21e7;hpb=04367bfc20c021c4105abf0c33b86d55f782d1e8;p=oota-llvm.git

diff --git a/docs/WritingAnLLVMPass.html b/docs/WritingAnLLVMPass.html
index c967000a9e0..ed985cdc98f 100644
--- a/docs/WritingAnLLVMPass.html
+++ b/docs/WritingAnLLVMPass.html
@@ -78,7 +78,8 @@
      <li><a href="#AU::addRequired">The <tt>AnalysisUsage::addRequired&lt;&gt;</tt> and <tt>AnalysisUsage::addRequiredTransitive&lt;&gt;</tt> methods</a></li>
      <li><a href="#AU::addPreserved">The <tt>AnalysisUsage::addPreserved&lt;&gt;</tt> method</a></li>
      <li><a href="#AU::examples">Example implementations of <tt>getAnalysisUsage</tt></a></li>
-     <li><a href="#getAnalysis">The <tt>getAnalysis&lt;&gt;</tt> and <tt>getAnalysisToUpdate&lt;&gt;</tt> methods</a></li>
+     <li><a href="#getAnalysis">The <tt>getAnalysis&lt;&gt;</tt> and
+<tt>getAnalysisIfAvailable&lt;&gt;</tt> methods</a></li>
      </ul></li>
   <li><a href="#analysisgroup">Implementing Analysis Groups</a>
      <ul>
@@ -178,7 +179,7 @@ source tree in the <tt>lib/Transforms/Hello</tt> directory.</p>
 <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
@@ -188,18 +189,13 @@ LIBRARYNAME = Hello
 # 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
+<tt>Debug+Asserts/lib/Hello.so</tt> shared object 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>
@@ -222,12 +218,14 @@ Start out with:</p>
 <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>"
 </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>
@@ -264,7 +262,7 @@ time.</p>
 
 <div class="doc_code"><pre>
      static char ID;
-     Hello() : FunctionPass((intptr_t)&amp;ID) {}
+     Hello() : FunctionPass(&amp;ID) {}
 </pre></div><p>
 
 <p> This declares pass identifier used by LLVM to identify pass. This allows LLVM to
@@ -272,7 +270,7 @@ avoid using expensive C++ runtime information.</p>
 
 <div class="doc_code"><pre>
     <b>virtual bool</b> <a href="#runOnFunction">runOnFunction</a>(Function &amp;F) {
-      llvm::cerr &lt;&lt; "<i>Hello: </i>" &lt;&lt; F.getName() &lt;&lt; "\n";
+      errs() &lt;&lt; "<i>Hello: </i>" &lt;&lt; F.getName() &lt;&lt; "\n";
       <b>return false</b>;
     }
   };  <i>// end of struct Hello</i>
@@ -292,19 +290,26 @@ function.</p>
 initialization value is not important.</p>
 
 <div class="doc_code"><pre>
-  RegisterPass&lt;Hello&gt; X("<i>hello</i>", "<i>Hello World Pass</i>");
+  RegisterPass&lt;Hello&gt; 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>
 
 <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>".</p>
+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>As a whole, the <tt>.cpp</tt> file looks like:</p>
 
 <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>
 
@@ -312,21 +317,22 @@ argument "<tt>hello</tt>", and a name "<tt>Hello World Pass</tt>".</p>
   <b>struct Hello</b> : <b>public</b> <a href="#FunctionPass">FunctionPass</a> {
     
     static char ID;
-    Hello() : FunctionPass((intptr_t)&amp;ID) {}
+    Hello() : FunctionPass(&amp;ID) {}
 
     <b>virtual bool</b> <a href="#runOnFunction">runOnFunction</a>(Function &amp;F) {
-      llvm::cerr &lt;&lt; "<i>Hello: </i>" &lt;&lt; F.getName() &lt;&lt; "\n";
+      errs() &lt;&lt; "<i>Hello: </i>" &lt;&lt; F.getName() &lt;&lt; "\n";
       <b>return false</b>;
     }
   };
   
+  char Hello::ID = 0;
   RegisterPass&lt;Hello&gt; X("<i>hello</i>", "<i>Hello World Pass</i>");
 }
 </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
+"<tt>Debug+Asserts/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>
@@ -352,7 +358,7 @@ through our transformation like this (or course, any bitcode file will
 work):</p>
 
 <div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -hello &lt; hello.bc &gt; /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -hello &lt; hello.bc &gt; /dev/null
 Hello: __main
 Hello: puts
 Hello: main
@@ -366,10 +372,10 @@ interesting way, we just throw away the result of <tt>opt</tt> (sending it to
 <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 -&gt; .bc modular optimizer
 
 USAGE: opt [options] &lt;input bitcode&gt;
@@ -397,7 +403,7 @@ the execution time of your pass along with the other passes you queue up.  For
 example:</p>
 
 <div class="doc_code"><pre>
-$ opt -load ../../../Debug/lib/Hello.so -hello -time-passes &lt; hello.bc &gt; /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -hello -time-passes &lt; hello.bc &gt; /dev/null
 Hello: __main
 Hello: puts
 Hello: main
@@ -442,7 +448,7 @@ available, from the most general to the most specific.</p>
 <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>
@@ -481,11 +487,17 @@ invalidated, and are never "run".</p>
 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&lt;DominatorTree&gt;(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&lt;DominatorTree&gt;(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
@@ -590,7 +602,7 @@ fast).</p>
 <div class="doc_text">
 
 <div class="doc_code"><pre>
-  <b>virtual bool</b> runOnSCC(const std::vector&lt;CallGraphNode *&gt; &amp;SCCM) = 0;
+  <b>virtual bool</b> runOnSCC(CallGraphSCC &amp;SCC) = 0;
 </pre></div>
 
 <p>The <tt>runOnSCC</tt> method performs the interesting work of the pass, and
@@ -892,16 +904,22 @@ finalization.</p>
 
 <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>
@@ -953,7 +971,7 @@ 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
 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
+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>
 
@@ -970,7 +988,7 @@ implement the virtual <tt>print</tt> method:</p>
 <div class="doc_text">
 
 <div class="doc_code"><pre>
-  <b>virtual void</b> print(llvm::OStream &amp;O, <b>const</b> Module *M) <b>const</b>;
+  <b>virtual void</b> print(std::ostream &amp;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
@@ -995,7 +1013,7 @@ depended on.</p>
 
 <div class="doc_text">
 
-<p>One of the main responsibilities of the <tt>PassManager</tt> is the make sure
+<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>
 tries to <a href="#passmanager">optimize the execution of passes</a> it must
 know how the passes interact with each other and what dependencies exist between
@@ -1123,7 +1141,8 @@ the fact that it hacks on the CFG.
 
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
-  <a name="getAnalysis">The <tt>getAnalysis&lt;&gt;</tt> and <tt>getAnalysisToUpdate&lt;&gt;</tt> methods</a>
+  <a name="getAnalysis">The <tt>getAnalysis&lt;&gt;</tt> and
+<tt>getAnalysisIfAvailable&lt;&gt;</tt> methods</a>
 </div>
 
 <div class="doc_text">
@@ -1165,12 +1184,12 @@ before returning a reference to the desired pass.</p>
 <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&lt;DominatorSet&gt;()) {
+  if (DominatorSet *DS = getAnalysisIfAvailable&lt;DominatorSet&gt;()) {
     <i>// A DominatorSet is active.  This code will update it.</i>
   }
   ...
@@ -1186,7 +1205,7 @@ it is active.  For example:</p>
 
 <div class="doc_text">
 
-<p>Now that we understand the basics of how passes are defined, how the are
+<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
 fancier.  All of the pass relationships that we have seen so far are very
 simple: one pass depends on one other specific pass to be run before it can run.
@@ -1375,7 +1394,8 @@ the LLVM program representation for a single function at a time, instead of
 traversing the entire program.  It reduces the memory consumption of compiler,
 because, for example, only one <a
 href="http://llvm.org/doxygen/classllvm_1_1DominatorSet.html"><tt>DominatorSet</tt></a>
-needs to be calculated at a time.  This also makes it possible some <a
+needs to be calculated at a time.  This also makes it possible to implement
+some <a
 href="#SMP">interesting enhancements</a> in the future.</p></li>
 
 </ol>
@@ -1391,14 +1411,14 @@ allowing any analysis results to live across the execution of your pass.</p>
 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 &lt; hello.bc &gt; /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -gcse -licm --debug-pass=Structure &lt; hello.bc &gt; /dev/null
 Module Pass Manager
   Function Pass Manager
     Dominator Set Construction
@@ -1435,7 +1455,7 @@ passes.</p>
 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 &lt; hello.bc &gt; /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -gcse -hello -licm --debug-pass=Structure &lt; hello.bc &gt; /dev/null
 Module Pass Manager
   Function Pass Manager
     Dominator Set Construction
@@ -1476,7 +1496,7 @@ href="#getAnalysisUsage"><tt>getAnalysisUsage</tt></a> method to our pass:</p>
 <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 &lt; hello.bc &gt; /dev/null
+$ opt -load ../../../Debug+Asserts/lib/Hello.so -gcse -hello -licm --debug-pass=Structure &lt; hello.bc &gt; /dev/null
 Pass Arguments:  -gcse -hello -licm
 Module Pass Manager
   Function Pass Manager
@@ -1526,7 +1546,7 @@ need some way to free analysis results when they are no longer useful.  The
 <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>
 
@@ -1606,12 +1626,12 @@ form; </p>
 </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
@@ -1654,7 +1674,7 @@ MachinePassRegistry RegisterMyPasses::Registry;
 
 <div class="doc_code"><pre>
   cl::opt&lt;RegisterMyPasses::FunctionPassCtor, false,
-          RegisterPassParser&lt;RegisterMyPasses&gt &gt
+          RegisterPassParser&lt;RegisterMyPasses&gt; &gt;
   MyPassOpt("mypass",
             cl::init(&amp;createDefaultMyPass),
             cl::desc("my pass option help")); 
@@ -1717,8 +1737,8 @@ want:</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 &amp;M) { return PM-&gt;run(M); }
 (gdb)
@@ -1804,9 +1824,9 @@ Despite that, we have kept the LLVM passes SMP ready, and you should too.</p>
 <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>