Identify Analysis pass.

Do not run analysis pass again if analysis info is still available.
This fixes PR1441.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48476 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 0 deletions

diff --git a/include/llvm/Analysis/PostDominators.h b/include/llvm/Analysis/PostDominators.h
index 07910e9538..c55022b763 100644
--- a/include/llvm/Analysis/PostDominators.h
+++ b/include/llvm/Analysis/PostDominators.h
@@ -29,6 +29,9 @@ struct PostDominatorTree : public FunctionPass {
     DT = new DominatorTreeBase<BasicBlock>(true);
   }
 
+  /// isAnalysis - Return true if this pass is  implementing an analysis pass.
+  virtual bool isAnalysis() const { return true; }
+
   virtual bool runOnFunction(Function &F);
 
   virtual void getAnalysisUsage(AnalysisUsage &AU) const {
@@ -69,6 +72,9 @@ struct PostDominanceFrontier : public DominanceFrontierBase {
   PostDominanceFrontier() 
     : DominanceFrontierBase((intptr_t) &ID, true) {}
 
+  /// isAnalysis - Return true if this pass is  implementing an analysis pass.
+  virtual bool isAnalysis() const { return true; }
+
   virtual bool runOnFunction(Function &) {
     Frontiers.clear();
     PostDominatorTree &DT = getAnalysis<PostDominatorTree>();