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simplify DeleteTriviallyDeadInstructions again, unlike my previous

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buggy rewrite, this notifies ScalarEvolution of a pending instruction
about to be removed and then erases it, instead of erasing it then 
notifying.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60329 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-12-01 06:11:32 +00:00
parent d8aafcb200
commit bfcee36cd7
1 changed files with 13 additions and 20 deletions
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33
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -244,28 +244,21 @@ DeleteTriviallyDeadInstructions(SetVector<Instruction*> &Insts) {
Instruction *I = Insts.back();
Insts.pop_back();
if (PHINode *PN = dyn_cast<PHINode>(I)) {
// If all incoming values to the Phi are the same, we can replace the Phi
// with that value.
if (Value *PNV = PN->hasConstantValue()) {
if (Instruction *U = dyn_cast<Instruction>(PNV))
if (!isInstructionTriviallyDead(I))
continue;
SE->deleteValueFromRecords(I);
for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) {
if (Instruction *U = dyn_cast<Instruction>(*i)) {
*i = 0;
if (U->use_empty())
Insts.insert(U);
SE->deleteValueFromRecords(PN);
PN->replaceAllUsesWith(PNV);
PN->eraseFromParent();
Changed = true;
continue;
}
}
if (isInstructionTriviallyDead(I)) {
for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
if (Instruction *U = dyn_cast<Instruction>(*i))
Insts.insert(U);
SE->deleteValueFromRecords(I);
I->eraseFromParent();
Changed = true;
}
I->eraseFromParent();
Changed = true;
}
}
@ -2067,7 +2060,7 @@ bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
BasicBlock::iterator I = L->getHeader()->begin();
while (PHINode *PN = dyn_cast<PHINode>(I++)) {
// At this point, we know that we have killed one or more IV users.
// It is worth checking to see if the cann indvar is also
// It is worth checking to see if the cannonical indvar is also
// dead, so that we can remove it as well.
//
// We can remove a PHI if it is on a cycle in the def-use graph