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Fix crash in LSR due to attempt to remove original induction variable. However,

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for reasons explained in the comments, I also deactivated this code as it needs
more thought.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20367 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jeff Cohen 2005-02-28 00:08:56 +00:00
parent 5e1e5e13ff
commit 14dc638081
1 changed files with 14 additions and 3 deletions
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17
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -78,9 +78,14 @@ DeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts) {
Instruction *I = *Insts.begin();
Insts.erase(Insts.begin());
if (isInstructionTriviallyDead(I)) {
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i)))
Insts.insert(U);
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
// Note: the PHI nodes had dropAllReferences() called on it, so its
// operands will all be NULL.
Value *V = I->getOperand(i);
if (V)
if (Instruction *U = dyn_cast<Instruction>(V))
Insts.insert(U);
}
I->getParent()->getInstList().erase(I);
Changed = true;
}
@ -237,6 +242,11 @@ void LoopStrengthReduce::runOnLoop(Loop *L) {
// 4. the add is used by the cann indvar
// If all four cases above are true, then we can remove both the add and
// the cann indvar.
#if 0
// FIXME: it's not clear this code is correct. An induction variable with
// but one use, an increment, implies an infinite loop. Not illegal, but
// of questionable utility. It also does not update the loop info with the
// new induction variable.
if (PN->hasOneUse()) {
BinaryOperator *BO = dyn_cast<BinaryOperator>(*(PN->use_begin()));
if (BO && BO->getOpcode() == Instruction::Add)
@ -250,5 +260,6 @@ void LoopStrengthReduce::runOnLoop(Loop *L) {
}
}
}
#endif
}
}