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Remove implicit_def instructions that become dead as result of coalescing. 

llvm-svn: 49513
This commit is contained in:
Evan Cheng 2008-04-10 23:48:35 +00:00
parent 2cb98eb4bb
commit c6864b6652
1 changed files with 37 additions and 19 deletions
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56
llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
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@ -632,8 +632,8 @@ SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
return;
unsigned LastUseIdx;
MachineOperand *LastUse =
lastRegisterUse(LR->start, CopyIdx-1, li.reg, LastUseIdx);
MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
LastUseIdx);
if (LastUse) {
// There are uses before the copy, just shorten the live range to the end
// of last use.
@ -714,29 +714,48 @@ bool SimpleRegisterCoalescing::CanCoalesceWithImpDef(MachineInstr *CopyMI,
/// identity copies so they will be removed.
void SimpleRegisterCoalescing::RemoveCopiesFromValNo(LiveInterval &li,
VNInfo *VNI) {
for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(li.reg),
UE = mri_->use_end(); UI != UE;) {
MachineInstr *UseMI = &*UI;
++UI;
if (JoinedCopies.count(UseMI))
MachineInstr *ImpDef = NULL;
MachineOperand *LastUse = NULL;
unsigned LastUseIdx = li_->getUseIndex(VNI->def);
for (MachineRegisterInfo::reg_iterator RI = mri_->reg_begin(li.reg),
RE = mri_->reg_end(); RI != RE;) {
MachineOperand *MO = &RI.getOperand();
MachineInstr *MI = &*RI;
++RI;
if (MO->isDef()) {
if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF) {
assert(!ImpDef && "Multiple implicit_def defining same register?");
ImpDef = MI;
}
continue;
unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
}
if (JoinedCopies.count(MI))
continue;
unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(MI));
LiveInterval::iterator ULR = li.FindLiveRangeContaining(UseIdx);
if (ULR->valno != VNI)
continue;
if (UseMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG)
continue;
// If the use is a copy, turn it into an identity copy.
unsigned SrcReg, DstReg;
if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg) || SrcReg != li.reg)
assert(0 && "Unexpected use of implicit def!");
// Each UseMI may have multiple uses of this register. Change them all.
for (unsigned i = 0, e = UseMI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = UseMI->getOperand(i);
if (MO.isReg() && MO.getReg() == li.reg)
MO.setReg(DstReg);
if (tii_->isMoveInstr(*MI, SrcReg, DstReg) && SrcReg == li.reg) {
// Each use MI may have multiple uses of this register. Change them all.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (MO.isReg() && MO.getReg() == li.reg)
MO.setReg(DstReg);
}
JoinedCopies.insert(MI);
} else if (UseIdx > LastUseIdx) {
LastUseIdx = UseIdx;
LastUse = MO;
}
JoinedCopies.insert(UseMI);
}
if (LastUse)
LastUse->setIsKill();
else {
// Remove dead implicit_def.
li_->RemoveMachineInstrFromMaps(ImpDef);
ImpDef->eraseFromParent();
}
}
@ -1874,7 +1893,6 @@ SimpleRegisterCoalescing::TurnCopyIntoImpDef(MachineBasicBlock::iterator &I,
assert(DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF);
li_->RemoveMachineInstrFromMaps(DefMI);
DefMI->eraseFromParent();
++numPeep;
}
}
++I;