fix PR17635: false positive with packed structures

LLVM optimizers may widen accesses to packed structures that overflow the structure itself, but should be in bounds up to the alignment of the object

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193317 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/MemoryBuiltins.h

@@ -228,6 +228,7 @@ class ObjectSizeOffsetEvaluator
   Value *Zero;
   CacheMapTy CacheMap;
   PtrSetTy SeenVals;
+  bool RoundToAlign;
 
   SizeOffsetEvalType unknown() {
     return std::make_pair((Value*)0, (Value*)0);
@@ -236,7 +237,7 @@ class ObjectSizeOffsetEvaluator
 
 public:
   ObjectSizeOffsetEvaluator(const DataLayout *DL, const TargetLibraryInfo *TLI,
-                            LLVMContext &Context);
+                            LLVMContext &Context, bool RoundToAlign = false);
   SizeOffsetEvalType compute(Value *V);
 
   bool knownSize(SizeOffsetEvalType SizeOffset) {