!SI.isVolatile()) {
if (LI == Val)
return EraseInstFromFunction(SI);
+ // load and store reference same memory location, the memory location
+ // is represented by getelementptr with two uses (load and store) and
+ // the getelementptr's base is alloca with single use. At this point,
+ // instructions from alloca to store can be removed.
+ // (this pattern is generated when bitfield is accessed.)
+ // For example,
+ // %u = alloca %struct.test, align 4 ; [#uses=1]
+ // %0 = getelementptr inbounds %struct.test* %u, i32 0, i32 0;[#uses=2]
+ // %1 = load i8* %0, align 4 ; [#uses=1]
+ // %2 = and i8 %1, -16 ; [#uses=1]
+ // %3 = or i8 %2, 5 ; [#uses=1]
+ // store i8 %3, i8* %0, align 4
if (Ptr->hasNUses(2)) {
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
if (isa<AllocaInst>(GEP->getOperand(0))) {