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Add a new BasicBlockPass::doInitialization/Finalization(Function &) pair of

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methods that may be useful for BasicBlockPasses.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3689 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2002-09-12 17:06:43 +00:00
parent e0a54f88a0
commit d0713f94af
2 changed files with 77 additions and 17 deletions
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67
docs/WritingAnLLVMPass.html
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@ -25,13 +25,19 @@
</ul>
<li><a href="#FunctionPass">The <tt>FunctionPass</tt> class</a>
<ul>
<li><a href="#doInitialization">The <tt>doInitialization</tt> method</a>
<li><a href="#doInitialization_mod">The <tt>doInitialization(Module
&amp;)</tt> method</a>
<li><a href="#runOnFunction">The <tt>runOnFunction</tt> method</a>
<li><a href="#doFinalization">The <tt>doFinalization</tt> method</a>
<li><a href="#doFinalization_mod">The <tt>doFinalization(Module
&amp;)</tt> method</a>
</ul>
<li><a href="#BasicBlockPass">The <tt>BasicBlockPass</tt> class</a>
<ul>
<li><a href="#doInitialization_fn">The <tt>doInitialization(Function
&amp;)</tt> method</a>
<li><a href="#runOnBasicBlock">The <tt>runOnBasicBlock</tt> method</a>
<li><a href="#doFinalization_fn">The <tt>doFinalization(Function
&amp;)</tt> method</a>
</ul>
</ul>
<li><a href="#registration">Pass Registration</a>
@ -424,8 +430,8 @@ 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>
<!-- _______________________________________________________________________ -->
</ul><h4><a name="doInitialization"><hr size=0>The <tt>doInitialization</tt>
method</h4><ul>
</ul><h4><a name="doInitialization_mod"><hr size=0>The
<tt>doInitialization(Module &amp;)</tt> method</h4><ul>
<pre>
<b>virtual bool</b> doInitialization(Module &amp;M);
@ -433,10 +439,11 @@ method</h4><ul>
The <tt>doIninitialize</tt> method is allowed to do most of the things that
<tt>FunctionPass</tt>'s are not allowed to do. They can add and remove
functions, get pointers to functions, etc. The <tt>doInitialize</tt> method is
designed to do simple initialization type of stuff that does not depend on the
functions being processed. The <tt>doInitialization</tt> function call is not
scheduled to overlap with any other pass executions.<p>
functions, get pointers to functions, etc. 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).<p>
A good example of how this method should be used is the <a
href="http://llvm.cs.uiuc.edu/doxygen/LowerAllocations_8cpp-source.html">LowerAllocations</a>
@ -457,7 +464,7 @@ transformation or analysis work of your pass. As usual, a true value should be
returned if the function is modified.<p>
<!-- _______________________________________________________________________ -->
</ul><h4><a name="doFinalization"><hr size=0>The <tt>doFinalization</tt> method</h4><ul>
</ul><h4><a name="doFinalization_mod"><hr size=0>The <tt>doFinalization(Module &amp;)</tt> method</h4><ul>
<pre>
<b>virtual bool</b> doFinalization(Module &amp;M);
@ -493,10 +500,26 @@ As such, they are <b>not</b> allowed to do any of the following:<p>
<tt>BasicBlockPass</tt>'s are useful for traditional local and "peephole"
optimizations. They may override the same <a
href="#doInitialization"><tt>doInitialization</tt></a> and <a
href="#doFinalization"><tt>doFinalization</tt></a> methods that <a
href="#FunctionPass"><tt>FunctionPass</tt></a>'s have, but also have a
<tt>runOnBasicBlock</tt> method:<p>
href="#doInitialization_mod"><tt>doInitialization(Module &amp;)</tt></a> and <a
href="#doFinalization_mod"><tt>doFinalization(Module &amp;)</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>
<!-- _______________________________________________________________________ -->
</ul><h4><a name="doInitialization_fn"><hr size=0>The
<tt>doInitialization(Function &amp;)</tt> method</h4><ul>
<pre>
<b>virtual bool</b> doInitialization(Function &amp;F);
</pre><p>
The <tt>doIninitialize</tt> method is allowed to do most of the things that
<tt>BasicBlockPass</tt>'s are not allowed to do, but that
<tt>FunctionPass</tt>'s can. The <tt>doInitialization</tt> method is designed
to do simple initialization type of stuff that does not depend on the
BasicBlocks being processed. The <tt>doInitialization</tt> method call is not
scheduled to overlap with any other pass executions (thus it should be very
fast).<p>
<!-- _______________________________________________________________________ -->
</ul><h4><a name="runOnBasicBlock"><hr size=0>The <tt>runOnBasicBlock</tt> method</h4><ul>
@ -511,6 +534,22 @@ parameter, and are not allowed to modify the CFG. A true value must be returned
if the basic block is modified.<p>
<!-- _______________________________________________________________________ -->
</ul><h4><a name="doFinalization_fn"><hr size=0>The <tt>doFinalization(Function
&amp;)</tt> method</h4><ul>
<pre>
<b>virtual bool</b> doFinalization(Function &amp;F);
</pre</p>
The <tt>doFinalization</tt> method is an infrequently used method that is called
when the pass framework has finished calling <a
href="#runOnBasicBlock"><tt>runOnBasicBlock</tt></a> for every BasicBlock in the
program being compiled. This can be used to perform per-function
finalization.<p>
<!-- *********************************************************************** -->
</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
@ -1164,6 +1203,6 @@ href="#Pass"><tt>Pass</tt></a>, only the other way around.<p>
<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
<!-- hhmts start -->
Last modified: Thu Sep 5 15:06:01 CDT 2002
Last modified: Thu Sep 12 11:46:40 CDT 2002
<!-- hhmts end -->
</font></body></html>

27
include/llvm/Pass.h
View File

@ -250,15 +250,36 @@ private:
/// 3. Optimizations conform to all of the contstraints of FunctionPass's.
///
struct BasicBlockPass : public FunctionPass {
/// doInitialization - Virtual method overridden by subclasses to do
/// any neccesary per-module initialization.
///
virtual bool doInitialization(Module &M) { return false; }
/// doInitialization - Virtual method overridden by BasicBlockPass subclasses
/// to do any neccesary per-function initialization.
///
virtual bool doInitialization(Function &F) { return false; }
/// runOnBasicBlock - Virtual method overriden by subclasses to do the
/// per-basicblock processing of the pass.
///
virtual bool runOnBasicBlock(BasicBlock &BB) = 0;
/// To run this pass on a function, we simply call runOnBasicBlock once for
/// each function.
/// doFinalization - Virtual method overriden by BasicBlockPass subclasses to
/// do any post processing needed after all passes have run.
///
virtual bool runOnFunction(Function &F);
virtual bool doFinalization(Function &F) { return false; }
/// doFinalization - Virtual method overriden by subclasses to do any post
/// processing needed after all passes have run.
///
virtual bool doFinalization(Module &M) { return false; }
// To run this pass on a function, we simply call runOnBasicBlock once for
// each function.
//
bool runOnFunction(Function &F);
/// To run directly on the basic block, we initialize, runOnBasicBlock, then
/// finalize.