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Another try at early partial coalescing. Identity phi source copies (their sources are defined by phi join def) are coalesced. And the phi join copy is backward copy propagated into the other copies. 

Still miscompiling some tests. :-(

llvm-svn: 81849
This commit is contained in:
Evan Cheng 2009-09-15 06:45:16 +00:00
parent d7490a4763
commit a38ff3edae
1 changed files with 58 additions and 60 deletions
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118
llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -1052,23 +1052,19 @@ void LiveIntervals::handleLiveInRegister(MachineBasicBlock *MBB,
bool
LiveIntervals::isProfitableToCoalesce(LiveInterval &DstInt, LiveInterval &SrcInt,
SmallVector<MachineInstr*,16> &IdentCopies,
SmallVector<MachineInstr*,16> &OtherCopies,
bool &HaveConflict) {
HaveConflict = false;
SmallVector<MachineInstr*,16> &OtherCopies) {
bool HaveConflict = false;
unsigned NumIdent = 0;
unsigned NumSources = 0;
for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(SrcInt.reg),
re = mri_->reg_end(); ri != re; ++ri) {
MachineOperand &O = ri.getOperand();
if (!O.isDef())
continue;
++NumSources;
MachineInstr *MI = &*ri;
unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
if (!tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg))
continue;
return false;
if (SrcReg != DstInt.reg) {
OtherCopies.push_back(MI);
HaveConflict |= DstInt.liveAt(getInstructionIndex(MI));
@ -1078,7 +1074,9 @@ LiveIntervals::isProfitableToCoalesce(LiveInterval &DstInt, LiveInterval &SrcInt
}
}
return NumSources >= 5 && (((float)NumIdent) / NumSources) > 0.20F;
if (!HaveConflict)
return false; // Let coalescer handle it
return IdentCopies.size() > OtherCopies.size();
}
void LiveIntervals::performEarlyCoalescing() {
@ -1104,78 +1102,78 @@ void LiveIntervals::performEarlyCoalescing() {
LiveInterval &SrcInt = getInterval(PHISrc);
SmallVector<MachineInstr*, 16> IdentCopies;
SmallVector<MachineInstr*, 16> OtherCopies;
bool HaveConflict;
if (!isProfitableToCoalesce(DstInt, SrcInt, IdentCopies, OtherCopies,
HaveConflict))
if (!isProfitableToCoalesce(DstInt, SrcInt, IdentCopies, OtherCopies))
continue;
DEBUG(errs() << "PHI Join: " << *Join);
assert(DstInt.containsOneValue() && "PHI join should have just one val#!");
VNInfo *VNI = DstInt.getValNumInfo(0);
VNInfo *NewVNI = HaveConflict
? 0 : SrcInt.getNextValue(VNI->def, 0, false, VNInfoAllocator);
// Now let's eliminate all the would-be identity copies.
for (unsigned i = 0, e = IdentCopies.size(); i != e; ++i) {
MachineInstr *PHICopy = IdentCopies[i];
DEBUG(errs() << "Coalescing: " << *PHICopy);
MachineBasicBlock *PHIMBB = PHICopy->getParent();
// Change the non-identity copies to directly target the phi destination.
for (unsigned i = 0, e = OtherCopies.size(); i != e; ++i) {
MachineInstr *PHICopy = OtherCopies[i];
DEBUG(errs() << "Moving: " << *PHICopy);
MachineInstrIndex MIIndex = getInstructionIndex(PHICopy);
MachineInstrIndex DefIndex = getDefIndex(MIIndex);
LiveRange *SLR = SrcInt.getLiveRangeContaining(DefIndex);
MachineInstrIndex StartIndex = HaveConflict
? SLR->start : getMBBStartIdx(PHIMBB);
MachineInstrIndex StartIndex = SLR->start;
MachineInstrIndex EndIndex = SLR->end;
// Delete val# defined by the now identity copy and add the range from
// beginning of the mbb to the end of the range.
SrcInt.removeValNo(SLR->valno);
if (HaveConflict) {
DEBUG(errs() << " added range [" << StartIndex << ','
<< EndIndex << "] to reg" << DstInt.reg << '\n');
DstInt.addRange(LiveRange(StartIndex, EndIndex, VNI));
// FIXME: Update uses of src to dst in this range?
} else {
DEBUG(errs() << " added range [" << StartIndex << ','
<< SLR->start << "] to reg" << SrcInt.reg << '\n');
SrcInt.addRange(LiveRange(StartIndex, EndIndex, NewVNI));
if (PHICopy->killsRegister(PHIDst))
EndIndex = DefIndex;
DEBUG(errs() << " added range [" << StartIndex << ','
<< EndIndex << "] to reg" << DstInt.reg << '\n');
if (DstInt.liveAt(StartIndex))
DstInt.removeRange(StartIndex, EndIndex);
VNInfo *NewVNI = DstInt.getNextValue(DefIndex, PHICopy, true,
VNInfoAllocator);
NewVNI->setHasPHIKill(true);
DstInt.addRange(LiveRange(StartIndex, EndIndex, NewVNI));
for (unsigned j = 0, ee = PHICopy->getNumOperands(); j != ee; ++j) {
MachineOperand &MO = PHICopy->getOperand(j);
if (!MO.isReg() || MO.getReg() != PHISrc)
continue;
MO.setReg(PHIDst);
}
}
// Now let's eliminate all the would-be identity copies.
for (unsigned i = 0, e = IdentCopies.size(); i != e; ++i) {
MachineInstr *PHICopy = IdentCopies[i];
DEBUG(errs() << "Coalescing: " << *PHICopy);
MachineInstrIndex MIIndex = getInstructionIndex(PHICopy);
MachineInstrIndex DefIndex = getDefIndex(MIIndex);
LiveRange *SLR = SrcInt.getLiveRangeContaining(DefIndex);
MachineInstrIndex StartIndex = SLR->start;
MachineInstrIndex EndIndex = SLR->end;
// Delete val# defined by the now identity copy and add the range from
// beginning of the mbb to the end of the range.
SrcInt.removeValNo(SLR->valno);
RemoveMachineInstrFromMaps(PHICopy);
PHICopy->eraseFromParent();
DEBUG(errs() << " added range [" << StartIndex << ','
<< EndIndex << "] to reg" << DstInt.reg << '\n');
DstInt.addRange(LiveRange(StartIndex, EndIndex, VNI));
}
if (HaveConflict) {
// First unset the kill.
for (unsigned i = 0, e = Join->getNumOperands(); i != e; ++i) {
MachineOperand &O = Join->getOperand(i);
if (!O.isReg() || O.getReg() != PHISrc)
continue;
if (O.isKill())
O.setIsKill(false);
}
MachineInstrIndex MIIndex = getInstructionIndex(Join);
MachineInstrIndex UseIndex = getUseIndex(MIIndex);
MachineInstrIndex DefIndex = getDefIndex(MIIndex);
LiveRange *SLR = SrcInt.getLiveRangeContaining(UseIndex);
LiveRange *DLR = DstInt.getLiveRangeContaining(DefIndex);
SrcInt.addRange(LiveRange(DLR->start, DLR->end, SLR->valno));
} else {
SrcInt.MergeValueInAsValue(DstInt, VNI, NewVNI);
// Change all references of phi source to destination.
for (MachineRegisterInfo::reg_iterator ri = mri_->reg_begin(PHIDst),
re = mri_->reg_end(); ri != re; ) {
MachineOperand &O = ri.getOperand();
++ri;
O.setReg(PHISrc);
}
removeInterval(DstInt.reg);
RemoveMachineInstrFromMaps(Join);
Join->eraseFromParent();
}
// Remove the phi join and update the phi block liveness.
MachineInstrIndex MIIndex = getInstructionIndex(Join);
MachineInstrIndex UseIndex = getUseIndex(MIIndex);
MachineInstrIndex DefIndex = getDefIndex(MIIndex);
LiveRange *SLR = SrcInt.getLiveRangeContaining(UseIndex);
LiveRange *DLR = DstInt.getLiveRangeContaining(DefIndex);
DLR->valno->setCopy(0);
DLR->valno->setIsDefAccurate(false);
DstInt.addRange(LiveRange(SLR->start, SLR->end, DLR->valno));
SrcInt.removeRange(SLR->start, SLR->end);
assert(SrcInt.empty());
removeInterval(PHISrc);
RemoveMachineInstrFromMaps(Join);
Join->eraseFromParent();
++numCoalescing;
}