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Check loop exit predicate properly while eliminating one iteration loop.

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This patch fixes PR 2869


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57369 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel
2008-10-10 22:02:57 +00:00
parent 875314bb52
commit fc19fbd2ca
2 changed files with 81 additions and 13 deletions
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28
lib/Transforms/Scalar/LoopIndexSplit.cpp
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@@ -585,16 +585,7 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
// only when index variable is equal to split value.
IndVar->replaceAllUsesWith(SD.SplitValue);
// Remove Latch to Header edge.
BasicBlock *LatchSucc = NULL;
Header->removePredecessor(Latch);
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
SI != E; ++SI) {
if (Header != *SI)
LatchSucc = *SI;
}
BR->setUnconditionalDest(LatchSucc);
Instruction *LTerminator = Latch->getTerminator();
Instruction *Terminator = Header->getTerminator();
Value *ExitValue = ExitCondition->getOperand(ExitValueNum);
@@ -606,12 +597,14 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
// c2 = icmp ult i32 SplitValue, ExitValue
// and i32 c1, c2
bool SignedPredicate = ExitCondition->isSignedPredicate();
CmpInst::Predicate C2Predicate = ExitCondition->getPredicate();
if (LTerminator->getOperand(0) != Header)
C2Predicate = CmpInst::getInversePredicate(C2Predicate);
Instruction *C1 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE,
SD.SplitValue, StartValue, "lisplit",
Terminator);
Instruction *C2 = new ICmpInst(SignedPredicate ?
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT,
Instruction *C2 = new ICmpInst(C2Predicate,
SD.SplitValue, ExitValue, "lisplit",
Terminator);
Instruction *NSplitCond = BinaryOperator::CreateAnd(C1, C2, "lisplit",
@@ -619,9 +612,18 @@ bool LoopIndexSplit::processOneIterationLoop(SplitInfo &SD) {
SD.SplitCondition->replaceAllUsesWith(NSplitCond);
SD.SplitCondition->eraseFromParent();
// Remove Latch to Header edge.
BasicBlock *LatchSucc = NULL;
Header->removePredecessor(Latch);
for (succ_iterator SI = succ_begin(Latch), E = succ_end(Latch);
SI != E; ++SI) {
if (Header != *SI)
LatchSucc = *SI;
}
BR->setUnconditionalDest(LatchSucc);
// Now, clear latch block. Remove instructions that are responsible
// to increment induction variable.
Instruction *LTerminator = Latch->getTerminator();
for (BasicBlock::iterator LB = Latch->begin(), LE = Latch->end();
LB != LE; ) {
Instruction *I = LB;