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Dead PHI instructions need to be handled specially.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48811 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2008-03-26 03:03:23 +00:00
parent 8a64d5ed37
commit d382f8a32d
1 changed files with 22 additions and 0 deletions
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22
lib/CodeGen/StrongPHIElimination.cpp
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@ -414,6 +414,12 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
while (P != FirstNonPHI && P->getOpcode() == TargetInstrInfo::PHI) {
unsigned DestReg = P->getOperand(0).getReg();
// Don't both doing PHI elimination for dead PHI's.
if (P->registerDefIsDead(DestReg)) {
++P;
continue;
}
LiveInterval& PI = LI.getOrCreateInterval(DestReg);
unsigned pIdx = LI.getInstructionIndex(FirstNonPHI);
VNInfo* PVN = PI.getLiveRangeContaining(pIdx)->valno;
@ -911,6 +917,22 @@ bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
for (std::vector<MachineInstr*>::iterator I = phis.begin(), E = phis.end();
I != E; ++I) {
// If this is a dead PHI node, then remove it from LiveIntervals.
unsigned DestReg = (*I)->getOperand(0).getReg();
if ((*I)->registerDefIsDead(DestReg)) {
LiveInterval& PI = LI.getInterval(DestReg);
if (PI.containsOneValue()) {
LI.removeInterval(DestReg);
} else {
MachineBasicBlock::iterator PIter = *I;
while (PIter->getOpcode() == TargetInstrInfo::PHI) ++PIter;
unsigned idx = LI.getInstructionIndex(PIter);
PI.removeRange(*PI.getLiveRangeContaining(idx), true);
}
}
LI.RemoveMachineInstrFromMaps(*I);
(*I)->eraseFromParent();
}