assert(mi->getOperand(si).isReg() && mi->getOperand(si).getReg() &&
mi->getOperand(si).isUse() && "two address instruction invalid");
- // If the two operands are the same we just remove the use
- // and mark the def as def&use, otherwise we have to insert a copy.
- if (mi->getOperand(ti).getReg() != mi->getOperand(si).getReg()) {
- // Rewrite:
- // a = b op c
- // to:
- // a = b
- // a = a op c
- unsigned regA = mi->getOperand(ti).getReg();
- unsigned regB = mi->getOperand(si).getReg();
- unsigned regASubIdx = mi->getOperand(ti).getSubReg();
-
- assert(TargetRegisterInfo::isVirtualRegister(regB) &&
- "cannot make instruction into two-address form");
+ // If the two operands are the same, nothing needs to be done.
+ if (mi->getOperand(ti).getReg() == mi->getOperand(si).getReg())
+ continue;
+
+ // Rewrite:
+ // a = b op c
+ // to:
+ // a = b
+ // a = a op c
+ unsigned regA = mi->getOperand(ti).getReg();
+ unsigned regB = mi->getOperand(si).getReg();
+ unsigned regASubIdx = mi->getOperand(ti).getSubReg();
+
+ assert(TargetRegisterInfo::isVirtualRegister(regB) &&
+ "cannot make instruction into two-address form");
#ifndef NDEBUG
- // First, verify that we don't have a use of a in the instruction (a =
- // b + a for example) because our transformation will not work. This
- // should never occur because we are in SSA form.
- for (unsigned i = 0; i != mi->getNumOperands(); ++i)
- assert(i == ti ||
- !mi->getOperand(i).isReg() ||
- mi->getOperand(i).getReg() != regA);
+ // First, verify that we don't have a use of a in the instruction (a =
+ // b + a for example) because our transformation will not work. This
+ // should never occur because we are in SSA form.
+ for (unsigned i = 0; i != mi->getNumOperands(); ++i)
+ assert(i == ti ||
+ !mi->getOperand(i).isReg() ||
+ mi->getOperand(i).getReg() != regA);
#endif
- // If this instruction is not the killing user of B, see if we can
- // rearrange the code to make it so. Making it the killing user will
- // allow us to coalesce A and B together, eliminating the copy we are
- // about to insert.
- 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.
- 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 this instruction is not the killing user of B, see if we can
+ // rearrange the code to make it so. Making it the killing user will
+ // allow us to coalesce A and B together, eliminating the copy we are
+ // about to insert.
+ 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.
+ 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;
}
-
- 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);
- }
- }
- }
-
- // We're really going to nuke the old inst. If regB was marked
- // as a kill we need to update its Kills list.
- if (mi->getOperand(si).isKill())
- LV->removeVirtualRegisterKilled(regB, mi);
-
- mbbi->erase(mi); // Nuke the old inst.
- mi = nmi;
- ++NumDeletes;
- break; // Done with this instruction.
+ 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 this instruction is commutative, check to see if C dies. If
- // so, swap the B and C operands. This makes the live ranges of A
- // and C joinable.
- // FIXME: This code also works for A := B op C instructions.
- unsigned SrcOp1, SrcOp2;
- if (TID.isCommutable() && mi->getNumOperands() >= 3 &&
- TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
- unsigned regC = 0;
- if (si == SrcOp1)
- regC = mi->getOperand(SrcOp2).getReg();
- else if (si == SrcOp2)
- regC = mi->getOperand(SrcOp1).getReg();
- if (isKilled(*mi, regC, MRI, TII)) {
- if (CommuteInstruction(mi, mbbi, regB, regC, Dist)) {
- ++NumCommuted;
- regB = regC;
- goto InstructionRearranged;
+ 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);
+ }
}
}
- }
- // If this instruction is potentially convertible to a true
- // three-address instruction,
- if (TID.isConvertibleTo3Addr()) {
- // FIXME: This assumes there are no more operands which are tied
- // to another register.
-#ifndef NDEBUG
- for (unsigned i = si + 1, e = TID.getNumOperands(); i < e; ++i)
- assert(TID.getOperandConstraint(i, TOI::TIED_TO) == -1);
-#endif
+ // We're really going to nuke the old inst. If regB was marked
+ // as a kill we need to update its Kills list.
+ if (mi->getOperand(si).isKill())
+ LV->removeVirtualRegisterKilled(regB, mi);
- if (ConvertInstTo3Addr(mi, nmi, mbbi, regB, Dist)) {
- ++NumConvertedTo3Addr;
- break; // Done with this instruction.
- }
+ mbbi->erase(mi); // Nuke the old inst.
+ mi = nmi;
+ ++NumDeletes;
+ break; // Done with this instruction.
}
}
- // If it's profitable to commute the instruction, do so.
+ // If this instruction is commutative, check to see if C dies. If
+ // so, swap the B and C operands. This makes the live ranges of A
+ // and C joinable.
+ // FIXME: This code also works for A := B op C instructions.
unsigned SrcOp1, SrcOp2;
if (TID.isCommutable() && mi->getNumOperands() >= 3 &&
TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
regC = mi->getOperand(SrcOp2).getReg();
else if (si == SrcOp2)
regC = mi->getOperand(SrcOp1).getReg();
-
- if (regC && isProfitableToCommute(regB, regC, mi, mbbi, Dist))
+ if (isKilled(*mi, regC, MRI, TII)) {
if (CommuteInstruction(mi, mbbi, regB, regC, Dist)) {
- ++NumAggrCommuted;
++NumCommuted;
regB = regC;
goto InstructionRearranged;
}
+ }
}
- // If it's profitable to convert the 2-address instruction to a
- // 3-address one, do so.
- if (TID.isConvertibleTo3Addr() && isProfitableToConv3Addr(regA)) {
+ // If this instruction is potentially convertible to a true
+ // three-address instruction,
+ if (TID.isConvertibleTo3Addr()) {
+ // FIXME: This assumes there are no more operands which are tied
+ // to another register.
+#ifndef NDEBUG
+ for (unsigned i = si + 1, e = TID.getNumOperands(); i < e; ++i)
+ assert(TID.getOperandConstraint(i, TOI::TIED_TO) == -1);
+#endif
+
if (ConvertInstTo3Addr(mi, nmi, mbbi, regB, Dist)) {
++NumConvertedTo3Addr;
break; // Done with this instruction.
}
}
+ }
+
+ // If it's profitable to commute the instruction, do so.
+ unsigned SrcOp1, SrcOp2;
+ if (TID.isCommutable() && mi->getNumOperands() >= 3 &&
+ TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
+ unsigned regC = 0;
+ if (si == SrcOp1)
+ regC = mi->getOperand(SrcOp2).getReg();
+ else if (si == SrcOp2)
+ regC = mi->getOperand(SrcOp1).getReg();
+
+ if (regC && isProfitableToCommute(regB, regC, mi, mbbi, Dist))
+ if (CommuteInstruction(mi, mbbi, regB, regC, Dist)) {
+ ++NumAggrCommuted;
+ ++NumCommuted;
+ regB = regC;
+ goto InstructionRearranged;
+ }
+ }
- InstructionRearranged:
- const TargetRegisterClass* rc = MRI->getRegClass(regB);
- MachineInstr *DefMI = MRI->getVRegDef(regB);
- // If it's safe and profitable, remat the definition instead of
- // copying it.
- if (DefMI &&
- DefMI->getDesc().isAsCheapAsAMove() &&
- DefMI->isSafeToReMat(TII, regB) &&
- isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist)){
- DEBUG(errs() << "2addr: REMATTING : " << *DefMI << "\n");
- TII->reMaterialize(*mbbi, mi, regA, regASubIdx, DefMI);
- ReMatRegs.set(regB);
- ++NumReMats;
- } else {
- bool Emitted = TII->copyRegToReg(*mbbi, mi, regA, regB, rc, rc);
- (void)Emitted;
- assert(Emitted && "Unable to issue a copy instruction!\n");
+ // If it's profitable to convert the 2-address instruction to a
+ // 3-address one, do so.
+ if (TID.isConvertibleTo3Addr() && isProfitableToConv3Addr(regA)) {
+ if (ConvertInstTo3Addr(mi, nmi, mbbi, regB, Dist)) {
+ ++NumConvertedTo3Addr;
+ break; // Done with this instruction.
}
+ }
+
+ InstructionRearranged:
+ const TargetRegisterClass* rc = MRI->getRegClass(regB);
+ MachineInstr *DefMI = MRI->getVRegDef(regB);
+ // If it's safe and profitable, remat the definition instead of
+ // copying it.
+ if (DefMI &&
+ DefMI->getDesc().isAsCheapAsAMove() &&
+ DefMI->isSafeToReMat(TII, regB) &&
+ isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist)){
+ DEBUG(errs() << "2addr: REMATTING : " << *DefMI << "\n");
+ TII->reMaterialize(*mbbi, mi, regA, regASubIdx, DefMI);
+ ReMatRegs.set(regB);
+ ++NumReMats;
+ } else {
+ bool Emitted = TII->copyRegToReg(*mbbi, mi, regA, regB, rc, rc);
+ (void)Emitted;
+ assert(Emitted && "Unable to issue a copy instruction!\n");
+ }
- MachineBasicBlock::iterator prevMI = prior(mi);
- // Update DistanceMap.
- DistanceMap.insert(std::make_pair(prevMI, Dist));
- DistanceMap[mi] = ++Dist;
+ MachineBasicBlock::iterator prevMI = prior(mi);
+ // Update DistanceMap.
+ DistanceMap.insert(std::make_pair(prevMI, Dist));
+ DistanceMap[mi] = ++Dist;
- // Update live variables for regB.
- if (LV) {
- if (LV->removeVirtualRegisterKilled(regB, mi))
- LV->addVirtualRegisterKilled(regB, prevMI);
+ // Update live variables for regB.
+ if (LV) {
+ if (LV->removeVirtualRegisterKilled(regB, mi))
+ LV->addVirtualRegisterKilled(regB, prevMI);
- if (LV->removeVirtualRegisterDead(regB, mi))
- LV->addVirtualRegisterDead(regB, prevMI);
- }
+ if (LV->removeVirtualRegisterDead(regB, mi))
+ LV->addVirtualRegisterDead(regB, prevMI);
+ }
- DEBUG(errs() << "\t\tprepend:\t" << *prevMI);
+ DEBUG(errs() << "\t\tprepend:\t" << *prevMI);
- // Replace all occurences of regB with regA.
- for (unsigned i = 0, e = mi->getNumOperands(); i != e; ++i) {
- if (mi->getOperand(i).isReg() &&
- mi->getOperand(i).getReg() == regB)
- mi->getOperand(i).setReg(regA);
- }
+ // Replace all occurences of regB with regA.
+ for (unsigned i = 0, e = mi->getNumOperands(); i != e; ++i) {
+ if (mi->getOperand(i).isReg() &&
+ mi->getOperand(i).getReg() == regB)
+ mi->getOperand(i).setReg(regA);
+ }
- assert(mi->getOperand(ti).isDef() && mi->getOperand(si).isUse());
- mi->getOperand(ti).setReg(mi->getOperand(si).getReg());
- MadeChange = true;
+ assert(mi->getOperand(ti).isDef() && mi->getOperand(si).isUse());
+ mi->getOperand(ti).setReg(mi->getOperand(si).getReg());
+ MadeChange = true;
- DEBUG(errs() << "\t\trewrite to:\t" << *mi);
- }
+ DEBUG(errs() << "\t\trewrite to:\t" << *mi);
}
mi = nmi;
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