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Remove some unneeded code for LiveInterval joining, and fix a bug in the Phi elimination algorithm where we were accidentally reasoning about

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the source rather than the destination.

llvm-svn: 48936
This commit is contained in:
Owen Anderson 2008-03-29 01:58:47 +00:00
parent 4d86275d23
commit 7d815aea28
1 changed files with 25 additions and 58 deletions
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83
lib/CodeGen/StrongPHIElimination.cpp
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@ -406,12 +406,9 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
// before the current one.
std::set<unsigned> ProcessedNames;
MachineBasicBlock::iterator FirstNonPHI = MBB->begin();
while (FirstNonPHI->getOpcode() == TargetInstrInfo::PHI) FirstNonPHI++;
// Iterate over all the PHI nodes in this block
MachineBasicBlock::iterator P = MBB->begin();
while (P != FirstNonPHI && P->getOpcode() == TargetInstrInfo::PHI) {
while (P->getOpcode() == TargetInstrInfo::PHI) {
unsigned DestReg = P->getOperand(0).getReg();
// Don't both doing PHI elimination for dead PHI's.
@ -421,7 +418,7 @@ void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
}
LiveInterval& PI = LI.getOrCreateInterval(DestReg);
unsigned pIdx = LI.getInstructionIndex(FirstNonPHI);
unsigned pIdx = LI.getDefIndex(LI.getInstructionIndex(P));
VNInfo* PVN = PI.getLiveRangeContaining(pIdx)->valno;
PhiValueNumber.insert(std::make_pair(DestReg, PVN->id));
@ -632,7 +629,7 @@ void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB,
map.insert(std::make_pair(I->first, I->first));
map.insert(std::make_pair(I->second, I->second));
if (!UsedByAnother.count(I->first)) {
if (!UsedByAnother.count(I->second)) {
worklist.insert(*I);
// Avoid iterator invalidation
@ -808,8 +805,6 @@ void StrongPHIElimination::mergeLiveIntervals(unsigned primary,
// coalesced.
SmallVector<int, 16> LHSValNoAssignments;
SmallVector<int, 16> RHSValNoAssignments;
DenseMap<VNInfo*, VNInfo*> LHSValsDefinedFromRHS;
DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
SmallVector<VNInfo*, 16> NewVNInfo;
LHSValNoAssignments.resize(LHS.getNumValNums(), -1);
@ -822,9 +817,9 @@ void StrongPHIElimination::mergeLiveIntervals(unsigned primary,
unsigned VN = VNI->id;
if (LHSValNoAssignments[VN] >= 0 || VNI->def == ~1U)
continue;
ComputeUltimateVN(VNI, NewVNInfo,
LHSValsDefinedFromRHS, RHSValsDefinedFromLHS,
LHSValNoAssignments, RHSValNoAssignments);
NewVNInfo.push_back(VNI);
LHSValNoAssignments[VN] = NewVNInfo.size()-1;
}
for (LiveInterval::vni_iterator I = RHS.vni_begin(), E = RHS.vni_end();
@ -833,51 +828,26 @@ void StrongPHIElimination::mergeLiveIntervals(unsigned primary,
unsigned VN = VNI->id;
if (RHSValNoAssignments[VN] >= 0 || VNI->def == ~1U)
continue;
// If this value number isn't a copy from the LHS, it's a new number.
if (RHSValsDefinedFromLHS.find(VNI) == RHSValsDefinedFromLHS.end()) {
NewVNInfo.push_back(VNI);
RHSValNoAssignments[VN] = NewVNInfo.size()-1;
continue;
}
ComputeUltimateVN(VNI, NewVNInfo,
RHSValsDefinedFromLHS, LHSValsDefinedFromRHS,
RHSValNoAssignments, LHSValNoAssignments);
NewVNInfo.push_back(VNI);
RHSValNoAssignments[VN] = NewVNInfo.size()-1;
}
// Update kill info. Some live ranges are extended due to copy coalescing.
for (DenseMap<VNInfo*, VNInfo*>::iterator I = LHSValsDefinedFromRHS.begin(),
E = LHSValsDefinedFromRHS.end(); I != E; ++I) {
VNInfo *VNI = I->first;
unsigned LHSValID = LHSValNoAssignments[VNI->id];
LiveInterval::removeKill(NewVNInfo[LHSValID], VNI->def);
NewVNInfo[LHSValID]->hasPHIKill |= VNI->hasPHIKill;
RHS.addKills(NewVNInfo[LHSValID], VNI->kills);
}
// Update kill info. Some live ranges are extended due to copy coalescing.
for (DenseMap<VNInfo*, VNInfo*>::iterator I = RHSValsDefinedFromLHS.begin(),
E = RHSValsDefinedFromLHS.end(); I != E; ++I) {
VNInfo *VNI = I->first;
unsigned RHSValID = RHSValNoAssignments[VNI->id];
LiveInterval::removeKill(NewVNInfo[RHSValID], VNI->def);
NewVNInfo[RHSValID]->hasPHIKill |= VNI->hasPHIKill;
LHS.addKills(NewVNInfo[RHSValID], VNI->kills);
}
// Use the VNInfo we collected earlier to ensure that the phi copy is
// merged correctly.
// FIXME: This is not working correctly yet.
// RHSValNoAssignments[secondaryVN] = primaryVN;
// If we get here, we know that we can coalesce the live ranges. Ask the
// intervals to coalesce themselves now.
LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], NewVNInfo);
LI.removeInterval(secondary);
// The valno that was previously the input to the PHI node
// now has a PHIKill.
LHS.getValNumInfo(RHSValNoAssignments[secondaryVN])->hasPHIKill = true;
}
bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
LiveIntervals& LI = getAnalysis<LiveIntervals>();
// Compute DFS numbers of each block
computeDFS(Fn);
@ -913,29 +883,26 @@ bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
phis.push_back(BI);
}
LiveIntervals& LI = getAnalysis<LiveIntervals>();
for (std::vector<MachineInstr*>::iterator I = phis.begin(), E = phis.end();
I != E; ++I) {
I != E; ) {
MachineInstr* PInstr = *(I++);
// If this is a dead PHI node, then remove it from LiveIntervals.
unsigned DestReg = (*I)->getOperand(0).getReg();
if ((*I)->registerDefIsDead(DestReg)) {
unsigned DestReg = PInstr->getOperand(0).getReg();
if (PInstr->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);
unsigned idx = LI.getDefIndex(LI.getInstructionIndex(PInstr));
PI.removeRange(*PI.getLiveRangeContaining(idx), true);
}
}
LI.RemoveMachineInstrFromMaps(*I);
(*I)->eraseFromParent();
LI.RemoveMachineInstrFromMaps(PInstr);
PInstr->eraseFromParent();
}
return false;
return true;
}