unsigned OpIdx = NewMI->findRegisterUseOperandIdx(IntA.reg, false);
NewMI->getOperand(OpIdx).setIsKill();
- // Update uses of IntA of the specific Val# with IntB.
bool BHasPHIKill = BValNo->hasPHIKill;
SmallVector<VNInfo*, 4> BDeadValNos;
SmallVector<unsigned, 4> BKills;
std::map<unsigned, unsigned> BExtend;
+
+ // If ALR and BLR overlaps and end of BLR extends beyond end of ALR, e.g.
+ // A = or A, B
+ // ...
+ // B = A
+ // ...
+ // C = A<kill>
+ // ...
+ // = B
+ //
+ // then do not add kills of A to the newly created B interval.
+ bool Extended = BLR->end > ALR->end && ALR->end != ALR->start;
+ if (Extended)
+ BExtend[ALR->end] = BLR->end;
+
+ // Update uses of IntA of the specific Val# with IntB.
for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
UE = mri_->use_end(); UI != UE;) {
MachineOperand &UseMO = UI.getOperand();
UseMO.setReg(NewReg);
if (UseMI == CopyMI)
continue;
- if (UseMO.isKill())
- BKills.push_back(li_->getUseIndex(UseIdx)+1);
+ if (UseMO.isKill()) {
+ if (Extended)
+ UseMO.setIsKill(false);
+ else
+ BKills.push_back(li_->getUseIndex(UseIdx)+1);
+ }
unsigned SrcReg, DstReg;
if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg))
continue;
JoinedCopies.insert(UseMI);
// If this is a kill but it's going to be removed, the last use
// of the same val# is the new kill.
- if (UseMO.isKill()) {
+ if (UseMO.isKill())
BKills.pop_back();
- }
}
}
}
}
+/// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
+/// due to live range lengthening as the result of coalescing.
+void SimpleRegisterCoalescing::RemoveUnnecessaryKills(unsigned Reg,
+ LiveInterval &LI) {
+ for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
+ UE = mri_->use_end(); UI != UE; ++UI) {
+ MachineOperand &UseMO = UI.getOperand();
+ if (UseMO.isKill()) {
+ MachineInstr *UseMI = UseMO.getParent();
+ unsigned SReg, DReg;
+ if (!tii_->isMoveInstr(*UseMI, SReg, DReg))
+ continue;
+ unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
+ if (JoinedCopies.count(UseMI))
+ continue;
+ LiveInterval::const_iterator UI = LI.FindLiveRangeContaining(UseIdx);
+ assert(UI != LI.end());
+ if (!LI.isKill(UI->valno, UseIdx+1))
+ UseMO.setIsKill(false);
+ }
+ }
+}
+
+/// ShortenDeadCopyLiveRange - Shorten a live range as it's artificially
+/// extended by a dead copy. Mark the last use (if any) of the val# as kill
+/// as ends the live range there. If there isn't another use, then this
+/// live range is dead.
+void SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li,
+ MachineInstr *CopyMI) {
+ unsigned CopyIdx = li_->getInstructionIndex(CopyMI);
+ LiveInterval::iterator MLR =
+ li.FindLiveRangeContaining(li_->getDefIndex(CopyIdx));
+ unsigned RemoveStart = MLR->start;
+ unsigned RemoveEnd = MLR->end;
+ unsigned LastUseIdx;
+ MachineOperand *LastUse = lastRegisterUse(RemoveStart, CopyIdx, li.reg,
+ LastUseIdx);
+ if (LastUse) {
+ // Shorten the liveinterval to the end of last use.
+ LastUse->setIsKill();
+ RemoveStart = li_->getDefIndex(LastUseIdx);
+ }
+ li.removeRange(RemoveStart, RemoveEnd, true);
+ if (li.empty())
+ li_->removeInterval(li.reg);
+}
+
/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
/// which are the src/dst of the copy instruction CopyMI. This returns true
/// if the copy was successfully coalesced away. If it is not currently
SrcInt.FindLiveRangeContaining(li_->getUseIndex(CopyIdx));
RemoveStart = SrcStart = SrcLR->start;
RemoveEnd = SrcEnd = SrcLR->end;
- // The instruction which defines the src is only truly dead if there are
- // no intermediate uses and there isn't a use beyond the copy.
- // FIXME: find the last use, mark is kill and shorten the live range.
if (SrcEnd > li_->getDefIndex(CopyIdx)) {
+ // If there are other uses of SrcReg beyond the copy, there is nothing to do.
isDead = false;
} else {
unsigned LastUseIdx;
MachineOperand *LastUse =
lastRegisterUse(SrcStart, CopyIdx, SrcReg, LastUseIdx);
if (LastUse) {
- // Shorten the liveinterval to the end of last use.
+ // There are uses before the copy, just shorten the live range to the end
+ // of last use.
LastUse->setIsKill();
isDead = false;
isShorten = true;
RemoveStart = li_->getDefIndex(LastUseIdx);
- RemoveEnd = SrcEnd;
} else {
+ // This live range is truly dead. Remove it.
MachineInstr *SrcMI = li_->getInstructionFromIndex(SrcStart);
if (SrcMI && SrcMI->modifiesRegister(SrcReg, tri_))
// A dead def should have a single cycle interval.
// Remember to delete the copy instruction.
JoinedCopies.insert(CopyMI);
+ // Some live range has been lengthened due to colaescing, eliminate the
+ // unnecessary kills.
+ RemoveUnnecessaryKills(SrcReg, *ResDstInt);
+ if (TargetRegisterInfo::isVirtualRegister(DstReg))
+ RemoveUnnecessaryKills(DstReg, *ResDstInt);
+
// SrcReg is guarateed to be the register whose live interval that is
// being merged.
li_->removeInterval(SrcReg);
}
-/// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
-/// due to live range lengthening as the result of coalescing.
void SimpleRegisterCoalescing::printRegName(unsigned reg) const {
if (TargetRegisterInfo::isPhysicalRegister(reg))
cerr << tri_->getName(reg);
if (tii_->isMoveInstr(*mii, srcReg, dstReg) && srcReg == dstReg) {
// remove from def list
LiveInterval &RegInt = li_->getOrCreateInterval(srcReg);
- MachineOperand *MO = mii->findRegisterDefOperand(dstReg, false);
// If def of this move instruction is dead, remove its live range from
// the dstination register's live interval.
- if (MO->isDead()) {
- unsigned MoveIdx = li_->getDefIndex(li_->getInstructionIndex(mii));
- LiveInterval::iterator MLR = RegInt.FindLiveRangeContaining(MoveIdx);
- RegInt.removeRange(MLR->start, MoveIdx+1, true);
- if (RegInt.empty())
- li_->removeInterval(srcReg);
- }
+ if (mii->registerDefIsDead(dstReg))
+ ShortenDeadCopyLiveRange(RegInt, mii);
li_->RemoveMachineInstrFromMaps(mii);
mii = mbbi->erase(mii);
++numPeep;
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