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Resubmit with fix. Properly remove the instructions except for landingpad, which should be removed only when its invokes are.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138932 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2011-09-01 01:28:11 +00:00
parent c1b4cd6c11
commit a8d1393093
1 changed files with 28 additions and 9 deletions
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37
lib/Transforms/InstCombine/InstructionCombining.cpp
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@ -1574,22 +1574,41 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (!Visited.count(BB)) {
Instruction *Term = BB->getTerminator();
while (Term != BB->begin()) { // Remove instrs bottom-up
BasicBlock::iterator I = Term; --I;
DEBUG(errs() << "IC: DCE: " << *I << '\n');
if (isa<TerminatorInst>(BB->begin()))
continue;
// Delete the instructions backwards, as it has a reduced likelihood of
// having to update as many def-use and use-def chains.
std::vector<Instruction*> WorkList;
WorkList.reserve(BB->size());
BasicBlock::iterator I = Term; --I;
while (true) {
if (!I->getType()->isVoidTy())
I->replaceAllUsesWith(UndefValue::get(I->getType()));
WorkList.push_back(I);
if (I == BB->begin())
break;
--I;
}
for (std::vector<Instruction*>::iterator
II = WorkList.begin(), IE = WorkList.end(); II != IE; ++II) {
Instruction *Inst = *II;
// Don't remove the landing pad. It should be removed only when its
// invokes are removed.
if (isa<LandingPadInst>(Inst))
continue;
// A debug intrinsic shouldn't force another iteration if we weren't
// going to do one without it.
if (!isa<DbgInfoIntrinsic>(I)) {
if (!isa<DbgInfoIntrinsic>(Inst)) {
++NumDeadInst;
MadeIRChange = true;
}
// If I is not void type then replaceAllUsesWith undef.
// This allows ValueHandlers and custom metadata to adjust itself.
if (!I->getType()->isVoidTy())
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
Inst->eraseFromParent();
}
}
}