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This patch removes some of useless instructions generated by bitfield access. 

llvm-svn: 127539
This commit is contained in:
Jin-Gu Kang 2011-03-12 12:18:44 +00:00
parent a862d95054
commit 2e939f7c3c
1 changed files with 13 additions and 3 deletions
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16
llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
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@ -429,9 +429,19 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
// the pointer we're loading and is producing the pointer we're storing,
// then *this* store is dead (X = load P; store X -> P).
if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
!SI.isVolatile())
return EraseInstFromFunction(SI);
if (equivalentAddressValues(LI->getOperand(0), Ptr) &&
!SI.isVolatile()) {
if (LI == Val)
return EraseInstFromFunction(SI);
if (Ptr->hasNUses(2)) {
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
if (isa<AllocaInst>(GEP->getOperand(0))) {
if (GEP->getOperand(0)->hasOneUse())
return EraseInstFromFunction(SI);
}
}
}
}
// Otherwise, this is a load from some other location. Stores before it
// may not be dead.