Enhance GVN to do more precise alias queries for non-local memory

references. For example, this allows gvn to eliminate the load in
this example:

  void foo(int n, int* p, int *q) {
    p[0] = 0;
    p[1] = 1;
    if (n) {
      *q = p[0];
    }
  }


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118714 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/AliasAnalysis.h

@@ -107,6 +107,12 @@ public:
       return Copy;
     }
 
+    Location getWithNewSize(uint64_t NewSize) const {
+      Location Copy(*this);
+      Copy.Size = NewSize;
+      return Copy;
+    }
+
     Location getWithoutTBAATag() const {
       Location Copy(*this);
       Copy.TBAATag = 0;