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Fix for PR4051. When 2address pass delete an instruction, update kill info when necessary.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70279 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2009-04-28 02:12:36 +00:00
parent c69d56f115
commit e9ccb3a7d4
2 changed files with 102 additions and 8 deletions
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87
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -88,6 +88,9 @@ namespace {
bool NoUseAfterLastDef(unsigned Reg, MachineBasicBlock *MBB, unsigned Dist,
unsigned &LastDef);
MachineInstr *FindLastUseInMBB(unsigned Reg, MachineBasicBlock *MBB,
unsigned Dist);
bool isProfitableToCommute(unsigned regB, unsigned regC,
MachineInstr *MI, MachineBasicBlock *MBB,
unsigned Dist);
@ -310,6 +313,28 @@ bool TwoAddressInstructionPass::NoUseAfterLastDef(unsigned Reg,
return !(LastUse > LastDef && LastUse < Dist);
}
MachineInstr *TwoAddressInstructionPass::FindLastUseInMBB(unsigned Reg,
MachineBasicBlock *MBB,
unsigned Dist) {
unsigned LastUseDist = Dist;
MachineInstr *LastUse = 0;
for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(Reg),
E = MRI->reg_end(); I != E; ++I) {
MachineOperand &MO = I.getOperand();
MachineInstr *MI = MO.getParent();
if (MI->getParent() != MBB)
continue;
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
if (DI == DistanceMap.end())
continue;
if (MO.isUse() && DI->second < LastUseDist) {
LastUse = DI->first;
LastUseDist = DI->second;
}
}
return LastUse;
}
/// isCopyToReg - Return true if the specified MI is a copy instruction or
/// a extract_subreg instruction. It also returns the source and destination
/// registers and whether they are physical registers by reference.
@ -684,7 +709,9 @@ void TwoAddressInstructionPass::ProcessCopy(MachineInstr *MI,
/// isSafeToDelete - If the specified instruction does not produce any side
/// effects and all of its defs are dead, then it's safe to delete.
static bool isSafeToDelete(MachineInstr *MI, const TargetInstrInfo *TII) {
static bool isSafeToDelete(MachineInstr *MI, unsigned Reg,
const TargetInstrInfo *TII,
SmallVector<unsigned, 4> &Kills) {
const TargetInstrDesc &TID = MI->getDesc();
if (TID.mayStore() || TID.isCall())
return false;
@ -693,10 +720,12 @@ static bool isSafeToDelete(MachineInstr *MI, const TargetInstrInfo *TII) {
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isDef())
if (!MO.isReg())
continue;
if (!MO.isDead())
if (MO.isDef() && !MO.isDead())
return false;
if (MO.isUse() && MO.getReg() != Reg && MO.isKill())
Kills.push_back(MO.getReg());
}
return true;
@ -787,11 +816,53 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
if (!isKilled(*mi, regB, MRI, TII)) {
// If regA is dead and the instruction can be deleted, just delete
// it so it doesn't clobber regB.
if (mi->getOperand(ti).isDead() && isSafeToDelete(mi, TII)) {
mbbi->erase(mi); // Nuke the old inst.
mi = nmi;
++NumDeletes;
break; // Done with this instruction.
SmallVector<unsigned, 4> Kills;
if (mi->getOperand(ti).isDead() &&
isSafeToDelete(mi, regB, TII, Kills)) {
SmallVector<std::pair<std::pair<unsigned, bool>
,MachineInstr*>, 4> NewKills;
bool ReallySafe = true;
// If this instruction kills some virtual registers, we need
// update the kill information. If it's not possible to do so,
// then bail out.
while (!Kills.empty()) {
unsigned Kill = Kills.back();
Kills.pop_back();
if (TargetRegisterInfo::isPhysicalRegister(Kill)) {
ReallySafe = false;
break;
}
MachineInstr *LastKill = FindLastUseInMBB(Kill, &*mbbi, Dist);
if (LastKill) {
bool isModRef = LastKill->modifiesRegister(Kill);
NewKills.push_back(std::make_pair(std::make_pair(Kill,isModRef),
LastKill));
} else {
ReallySafe = false;
break;
}
}
if (ReallySafe) {
if (LV) {
while (!NewKills.empty()) {
MachineInstr *NewKill = NewKills.back().second;
unsigned Kill = NewKills.back().first.first;
bool isDead = NewKills.back().first.second;
NewKills.pop_back();
if (LV->removeVirtualRegisterKilled(Kill, mi)) {
if (isDead)
LV->addVirtualRegisterDead(Kill, NewKill);
else
LV->addVirtualRegisterKilled(Kill, NewKill);
}
}
}
mbbi->erase(mi); // Nuke the old inst.
mi = nmi;
++NumDeletes;
break; // Done with this instruction.
}
}
// If this instruction is commutative, check to see if C dies. If