objectsize: add support for GEPs with non-constant indexes

add an additional parameter to InstCombiner::EmitGEPOffset() to force it to *not* emit operations with NUW flag

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156585 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 6a39fc33d4..8420a6a96e 100644
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -423,7 +423,8 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
 /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
 /// code necessary to compute the offset from the base pointer (without adding
 /// in the base pointer).  Return the result as a signed integer of intptr size.
-Value *InstCombiner::EmitGEPOffset(User *GEP) {
+/// If NoNUW is true, then the NUW flag is not used.
+Value *InstCombiner::EmitGEPOffset(User *GEP, bool NoNUW) {
   TargetData &TD = *getTargetData();
   gep_type_iterator GTI = gep_type_begin(GEP);
   Type *IntPtrTy = TD.getIntPtrType(GEP->getContext());
@@ -431,7 +432,7 @@ Value *InstCombiner::EmitGEPOffset(User *GEP) {
 
   // If the GEP is inbounds, we know that none of the addressing operations will
   // overflow in an unsigned sense.
-  bool isInBounds = cast<GEPOperator>(GEP)->isInBounds();
+  bool isInBounds = cast<GEPOperator>(GEP)->isInBounds() && !NoNUW;
   
   // Build a mask for high order bits.
   unsigned IntPtrWidth = TD.getPointerSizeInBits();