return false;
}
-/// isElidable - If the value of this instruction and the memory it writes to is
-/// unused, may we delete this instrtction?
-static bool isElidable(Instruction *I) {
+/// isRemovable - If the value of this instruction and the memory it writes to
+/// is unused, may we delete this instruction?
+static bool isRemovable(Instruction *I) {
assert(hasMemoryWrite(I));
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
return II->getIntrinsicID() != Intrinsic::lifetime_end;
bool DSE::runOnBasicBlock(BasicBlock &BB) {
MemoryDependenceAnalysis &MD = getAnalysis<MemoryDependenceAnalysis>();
+ AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
TD = getAnalysisIfAvailable<TargetData>();
bool MadeChange = false;
}
}
}
-
+
if (!InstDep.isDef()) {
// If this is a may-aliased store that is clobbering the store value, we
// can keep searching past it for another must-aliased pointer that stores
// we can remove the first store to P even though we don't know if P and Q
// alias.
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
AliasAnalysis::Location Loc = AA.getLocation(SI);
while (InstDep.isClobber() && InstDep.getInst() != &BB.front()) {
// Can't look past this instruction if it might read 'Loc'.
// long as this store is at least as big as it.
if (InstDep.isDef() && hasMemoryWrite(InstDep.getInst())) {
Instruction *DepStore = InstDep.getInst();
- if (isStoreAtLeastAsWideAs(Inst, DepStore, TD) && isElidable(DepStore)) {
- // Delete the store and now-dead instructions that feed it.
- DeleteDeadInstruction(DepStore);
- ++NumFastStores;
- MadeChange = true;
-
- // DeleteDeadInstruction can delete the current instruction in loop
- // cases, reset BBI.
- BBI = Inst;
- if (BBI != BB.begin())
- --BBI;
+ if (!isRemovable(DepStore) ||
+ !isStoreAtLeastAsWideAs(Inst, DepStore, TD))
continue;
- }
+
+ // Delete the store and now-dead instructions that feed it.
+ DeleteDeadInstruction(DepStore);
+ ++NumFastStores;
+ MadeChange = true;
+
+ // DeleteDeadInstruction can delete the current instruction in loop
+ // cases, reset BBI.
+ BBI = Inst;
+ if (BBI != BB.begin())
+ --BBI;
+ continue;
}
}
if (Dep.isNonLocal()) return false;
Instruction *Dependency = Dep.getInst();
- if (!hasMemoryWrite(Dependency) || !isElidable(Dependency))
+ if (!hasMemoryWrite(Dependency) || !isRemovable(Dependency))
return false;
Value *DepPointer = getPointerOperand(Dependency)->getUnderlyingObject();
// If we find a store whose pointer is dead.
if (hasMemoryWrite(BBI)) {
- if (isElidable(BBI)) {
+ if (isRemovable(BBI)) {
// See through pointer-to-pointer bitcasts
Value *pointerOperand = getPointerOperand(BBI)->getUnderlyingObject();