Move the capture analysis from MemoryDependencyAnalysis to a more general place

so that it can be reused in MemCpyOptimizer.  This analysis is needed to remove
an unnecessary memcpy when returning a struct into a local variable.
rdar://11341081
PR12686


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156776 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/AliasAnalysis.h

@@ -50,6 +50,7 @@ class Pass;
 class AnalysisUsage;
 class MemTransferInst;
 class MemIntrinsic;
+class DominatorTree;
 
 class AliasAnalysis {
 protected:
@@ -462,6 +463,18 @@ public:
   virtual ModRefResult getModRefInfo(ImmutableCallSite CS1,
                                      ImmutableCallSite CS2);
 
+  /// callCapturesBefore - Return information about whether a particular call 
+  /// site modifies or reads the specified memory location.
+  ModRefResult callCapturesBefore(const Instruction *I,
+                                  const AliasAnalysis::Location &MemLoc,
+                                  DominatorTree *DT);
+
+  /// callCapturesBefore - A convenience wrapper.
+  ModRefResult callCapturesBefore(const Instruction *I, const Value *P,
+                                  uint64_t Size, DominatorTree *DT) {
+    return callCapturesBefore(I, Location(P, Size), DT);
+  }
+
   //===--------------------------------------------------------------------===//
   /// Higher level methods for querying mod/ref information.
   ///

include/llvm/Analysis/MemoryDependenceAnalysis.h

@@ -431,9 +431,6 @@ 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;