From 9b5e8e5c32b68e2f7c337f9a7e59de04c7fd5737 Mon Sep 17 00:00:00 2001 From: Devang Patel Date: Mon, 16 Apr 2007 21:28:14 +0000 Subject: Document how, module pass can require function pass. llvm-svn: 36171 --- llvm/docs/WritingAnLLVMPass.html | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'llvm/docs/WritingAnLLVMPass.html') diff --git a/llvm/docs/WritingAnLLVMPass.html b/llvm/docs/WritingAnLLVMPass.html index 3b116074b71..c9813ef11c5 100644 --- a/llvm/docs/WritingAnLLVMPass.html +++ b/llvm/docs/WritingAnLLVMPass.html @@ -466,7 +466,9 @@ class is the most general of all superclasses that you can use. Deriving from ModulePass indicates that your pass uses the entire program as a unit, refering to function bodies in no predictable order, or adding and removing functions. Because nothing is known about the behavior of ModulePass -subclasses, no optimization can be done for their execution.

+subclasses, no optimization can be done for their execution. A module pass +can use function level passes (e.g. dominators) using getAnalysis interface + getAnalysis(Function).

To write a correct ModulePass subclass, derive from ModulePass and overload the runOnModule method with the @@ -1127,7 +1129,21 @@ runtime assertion failure if you attempt to get an analysis that you did not declare as required in your getAnalysisUsage implementation. This method can be called by your run* method implementation, or by any -other local method invoked by your run* method.

+other local method invoked by your run* method. + +A module level pass can use function level analysis info using this interface. +For example:

+ +
+   bool ModuleLevelPass::runOnModule(Module &M) {
+     ...
+     DominatorTree &DT = getAnalysis<DominatorTree>(Function &F);
+     ...
+   }
+
+ +In above example, runOnFunction for DominatorTree is called by pass manager +before returning a reference to the desired pass.

If your pass is capable of updating analyses if they exist (e.g., -- cgit v1.2.3