Refactor capture tracking (which already had a couple flags for whether returns

and stores capture) to permit the caller to see each capture point and decide
whether to continue looking.

Use this inside memdep to do an analysis that basicaa won't do. This lets us
solve another devirtualization case, fixing PR8908!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144580 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/MemoryDependenceAnalysis.h

@@ -324,6 +324,7 @@ namespace llvm {
     /// Current AA implementation, just a cache.
     AliasAnalysis *AA;
     TargetData *TD;
+    DominatorTree *DT;
     OwningPtr<PredIteratorCache> PredCache;
   public:
     MemoryDependenceAnalysis();
@@ -430,6 +431,9 @@ namespace llvm {
 
     void RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P);
     
+    AliasAnalysis::ModRefResult
+    getModRefInfo(const Instruction *Inst, const AliasAnalysis::Location &Loc);
+
     /// verifyRemoved - Verify that the specified instruction does not occur
     /// in our internal data structures.
     void verifyRemoved(Instruction *Inst) const;