- VirtRegMap::MI2VirtMapTy::const_iterator I, End;
- bool Erased = false;
- bool BackTracked = false;
- if (PrepForUnfoldOpti(MBB, MII,
- MaybeDeadStores, Spills, RegKills, KillOps, VRM))
- NextMII = next(MII);
-
- MachineInstr &MI = *MII;
-
- if (VRM.hasEmergencySpills(&MI)) {
- // Spill physical register(s) in the rare case the allocator has run out
- // of registers to allocate.
- SmallSet<int, 4> UsedSS;
- std::vector<unsigned> &EmSpills = VRM.getEmergencySpills(&MI);
- for (unsigned i = 0, e = EmSpills.size(); i != e; ++i) {
- unsigned PhysReg = EmSpills[i];
- const TargetRegisterClass *RC =
- TRI->getPhysicalRegisterRegClass(PhysReg);
- assert(RC && "Unable to determine register class!");
- int SS = VRM.getEmergencySpillSlot(RC);
- if (UsedSS.count(SS))
- assert(0 && "Need to spill more than one physical registers!");
- UsedSS.insert(SS);
- TII->storeRegToStackSlot(MBB, MII, PhysReg, true, SS, RC);
- MachineInstr *StoreMI = prior(MII);
- VRM.addSpillSlotUse(SS, StoreMI);
- TII->loadRegFromStackSlot(MBB, next(MII), PhysReg, SS, RC);
- MachineInstr *LoadMI = next(MII);
- VRM.addSpillSlotUse(SS, LoadMI);
- ++NumPSpills;
- }
- NextMII = next(MII);
- }
-
- // Insert restores here if asked to.
- if (VRM.isRestorePt(&MI)) {
- std::vector<unsigned> &RestoreRegs = VRM.getRestorePtRestores(&MI);
- for (unsigned i = 0, e = RestoreRegs.size(); i != e; ++i) {
- unsigned VirtReg = RestoreRegs[e-i-1]; // Reverse order.
- if (!VRM.getPreSplitReg(VirtReg))
- continue; // Split interval spilled again.
- unsigned Phys = VRM.getPhys(VirtReg);
- RegInfo->setPhysRegUsed(Phys);
-
- // Check if the value being restored if available. If so, it must be
- // from a predecessor BB that fallthrough into this BB. We do not
- // expect:
- // BB1:
- // r1 = load fi#1
- // ...
- // = r1<kill>
- // ... # r1 not clobbered
- // ...
- // = load fi#1
- bool DoReMat = VRM.isReMaterialized(VirtReg);
- int SSorRMId = DoReMat
- ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
- const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
- unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
- if (InReg == Phys) {
- // If the value is already available in the expected register, save
- // a reload / remat.
- if (SSorRMId)
- DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
- else
- DOUT << "Reusing SS#" << SSorRMId;
- DOUT << " from physreg "
- << TRI->getName(InReg) << " for vreg"
- << VirtReg <<" instead of reloading into physreg "
- << TRI->getName(Phys) << "\n";
- ++NumOmitted;
- continue;
- } else if (InReg && InReg != Phys) {
- if (SSorRMId)
- DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
- else
- DOUT << "Reusing SS#" << SSorRMId;
- DOUT << " from physreg "
- << TRI->getName(InReg) << " for vreg"
- << VirtReg <<" by copying it into physreg "
- << TRI->getName(Phys) << "\n";
-
- // If the reloaded / remat value is available in another register,
- // copy it to the desired register.
- TII->copyRegToReg(MBB, &MI, Phys, InReg, RC, RC);
-
- // This invalidates Phys.
- Spills.ClobberPhysReg(Phys);
- // Remember it's available.
- Spills.addAvailable(SSorRMId, Phys);
-
- // Mark is killed.
- MachineInstr *CopyMI = prior(MII);
- MachineOperand *KillOpnd = CopyMI->findRegisterUseOperand(InReg);
- KillOpnd->setIsKill();
- UpdateKills(*CopyMI, RegKills, KillOps, TRI);
-
- DOUT << '\t' << *CopyMI;
- ++NumCopified;
- continue;
- }
-
- if (VRM.isReMaterialized(VirtReg)) {
- ReMaterialize(MBB, MII, Phys, VirtReg, TII, TRI, VRM);
- } else {
- const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
- TII->loadRegFromStackSlot(MBB, &MI, Phys, SSorRMId, RC);
- MachineInstr *LoadMI = prior(MII);
- VRM.addSpillSlotUse(SSorRMId, LoadMI);
- ++NumLoads;
- }
-
- // This invalidates Phys.
- Spills.ClobberPhysReg(Phys);
- // Remember it's available.
- Spills.addAvailable(SSorRMId, Phys);
-
- UpdateKills(*prior(MII), RegKills, KillOps, TRI);
- DOUT << '\t' << *prior(MII);
- }
- }
-
- // Insert spills here if asked to.
- if (VRM.isSpillPt(&MI)) {
- std::vector<std::pair<unsigned,bool> > &SpillRegs =
- VRM.getSpillPtSpills(&MI);
-
- for (unsigned i = 0, e = SpillRegs.size(); i != e; ++i) {
- unsigned VirtReg = SpillRegs[i].first;
- bool isKill = SpillRegs[i].second;
- if (!VRM.getPreSplitReg(VirtReg))
- continue; // Split interval spilled again.
- const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
- unsigned Phys = VRM.getPhys(VirtReg);
- int StackSlot = VRM.getStackSlot(VirtReg);
- TII->storeRegToStackSlot(MBB, next(MII), Phys, isKill, StackSlot, RC);
- MachineInstr *StoreMI = next(MII);
- VRM.addSpillSlotUse(StackSlot, StoreMI);
- DOUT << "Store:\t" << *StoreMI;
- VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
- AddedSpills.push_back(StoreMI);
- }
-
- NextMII = next(MII);
- }
-
- /// ReusedOperands - Keep track of operand reuse in case we need to undo
- /// reuse.
- ReuseInfo ReusedOperands(MI, TRI);
- SmallVector<unsigned, 4> VirtUseOps;
- for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI.getOperand(i);
- if (!MO.isReg() || MO.getReg() == 0)
- continue; // Ignore non-register operands.
-
- unsigned VirtReg = MO.getReg();
- if (TargetRegisterInfo::isPhysicalRegister(VirtReg)) {
- // Ignore physregs for spilling, but remember that it is used by this
- // function.
- RegInfo->setPhysRegUsed(VirtReg);
- continue;
- }
-
- // We want to process implicit virtual register uses first.
- if (MO.isImplicit())
- // If the virtual register is implicitly defined, emit a implicit_def
- // before so scavenger knows it's "defined".
- VirtUseOps.insert(VirtUseOps.begin(), i);
- else
- VirtUseOps.push_back(i);
- }
-
- // Process all of the spilled uses and all non spilled reg references.
- SmallVector<int, 2> PotentialDeadStoreSlots;
- KilledMIRegs.clear();
- for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) {
- unsigned i = VirtUseOps[j];
- MachineOperand &MO = MI.getOperand(i);
- unsigned VirtReg = MO.getReg();
- assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
- "Not a virtual register?");
-
- unsigned SubIdx = MO.getSubReg();
- if (VRM.isAssignedReg(VirtReg)) {
- // This virtual register was assigned a physreg!
- unsigned Phys = VRM.getPhys(VirtReg);
- RegInfo->setPhysRegUsed(Phys);
- if (MO.isDef())
- ReusedOperands.markClobbered(Phys);
- unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
- MI.getOperand(i).setReg(RReg);
- if (VRM.isImplicitlyDefined(VirtReg))
- BuildMI(MBB, &MI, MI.getDebugLoc(),
- TII->get(TargetInstrInfo::IMPLICIT_DEF), RReg);
- continue;
- }
-
- // This virtual register is now known to be a spilled value.
- if (!MO.isUse())
- continue; // Handle defs in the loop below (handle use&def here though)
-
- bool DoReMat = VRM.isReMaterialized(VirtReg);
- int SSorRMId = DoReMat
- ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
- int ReuseSlot = SSorRMId;
-
- // Check to see if this stack slot is available.
- unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
-
- // If this is a sub-register use, make sure the reuse register is in the
- // right register class. For example, for x86 not all of the 32-bit
- // registers have accessible sub-registers.
- // Similarly so for EXTRACT_SUBREG. Consider this:
- // EDI = op
- // MOV32_mr fi#1, EDI
- // ...
- // = EXTRACT_SUBREG fi#1
- // fi#1 is available in EDI, but it cannot be reused because it's not in
- // the right register file.
- if (PhysReg &&
- (SubIdx || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
- const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
- if (!RC->contains(PhysReg))
- PhysReg = 0;
- }
-
- if (PhysReg) {
- // This spilled operand might be part of a two-address operand. If this
- // is the case, then changing it will necessarily require changing the
- // def part of the instruction as well. However, in some cases, we
- // aren't allowed to modify the reused register. If none of these cases
- // apply, reuse it.
- bool CanReuse = true;
- bool isTied = MI.isRegTiedToDefOperand(i);
- if (isTied) {
- // Okay, we have a two address operand. We can reuse this physreg as
- // long as we are allowed to clobber the value and there isn't an
- // earlier def that has already clobbered the physreg.
- CanReuse = !ReusedOperands.isClobbered(PhysReg) &&
- Spills.canClobberPhysReg(PhysReg);
- }
-
- if (CanReuse) {
- // If this stack slot value is already available, reuse it!
- if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
- DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
- else
- DOUT << "Reusing SS#" << ReuseSlot;
- DOUT << " from physreg "
- << TRI->getName(PhysReg) << " for vreg"
- << VirtReg <<" instead of reloading into physreg "
- << TRI->getName(VRM.getPhys(VirtReg)) << "\n";
- unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
- MI.getOperand(i).setReg(RReg);
-
- // The only technical detail we have is that we don't know that
- // PhysReg won't be clobbered by a reloaded stack slot that occurs
- // later in the instruction. In particular, consider 'op V1, V2'.
- // If V1 is available in physreg R0, we would choose to reuse it
- // here, instead of reloading it into the register the allocator
- // indicated (say R1). However, V2 might have to be reloaded
- // later, and it might indicate that it needs to live in R0. When
- // this occurs, we need to have information available that
- // indicates it is safe to use R1 for the reload instead of R0.
- //
- // To further complicate matters, we might conflict with an alias,
- // or R0 and R1 might not be compatible with each other. In this
- // case, we actually insert a reload for V1 in R1, ensuring that
- // we can get at R0 or its alias.
- ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
- VRM.getPhys(VirtReg), VirtReg);
- if (isTied)
- // Only mark it clobbered if this is a use&def operand.
- ReusedOperands.markClobbered(PhysReg);
- ++NumReused;
-
- if (MI.getOperand(i).isKill() &&
- ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
-
- // The store of this spilled value is potentially dead, but we
- // won't know for certain until we've confirmed that the re-use
- // above is valid, which means waiting until the other operands
- // are processed. For now we just track the spill slot, we'll
- // remove it after the other operands are processed if valid.
-
- PotentialDeadStoreSlots.push_back(ReuseSlot);
- }
-
- // Mark is isKill if it's there no other uses of the same virtual
- // register and it's not a two-address operand. IsKill will be
- // unset if reg is reused.
- if (!isTied && KilledMIRegs.count(VirtReg) == 0) {
- MI.getOperand(i).setIsKill();
- KilledMIRegs.insert(VirtReg);
- }
-
- continue;
- } // CanReuse
-
- // Otherwise we have a situation where we have a two-address instruction
- // whose mod/ref operand needs to be reloaded. This reload is already
- // available in some register "PhysReg", but if we used PhysReg as the
- // operand to our 2-addr instruction, the instruction would modify
- // PhysReg. This isn't cool if something later uses PhysReg and expects
- // to get its initial value.
- //
- // To avoid this problem, and to avoid doing a load right after a store,
- // we emit a copy from PhysReg into the designated register for this
- // operand.
- unsigned DesignatedReg = VRM.getPhys(VirtReg);
- assert(DesignatedReg && "Must map virtreg to physreg!");
-
- // Note that, if we reused a register for a previous operand, the
- // register we want to reload into might not actually be
- // available. If this occurs, use the register indicated by the
- // reuser.
- if (ReusedOperands.hasReuses())
- DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI,
- Spills, MaybeDeadStores, RegKills, KillOps, VRM);
-
- // If the mapped designated register is actually the physreg we have
- // incoming, we don't need to inserted a dead copy.
- if (DesignatedReg == PhysReg) {
- // If this stack slot value is already available, reuse it!
- if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
- DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
- else
- DOUT << "Reusing SS#" << ReuseSlot;
- DOUT << " from physreg " << TRI->getName(PhysReg)
- << " for vreg" << VirtReg
- << " instead of reloading into same physreg.\n";
- unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
- MI.getOperand(i).setReg(RReg);
- ReusedOperands.markClobbered(RReg);
- ++NumReused;
- continue;
- }
-
- const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
- RegInfo->setPhysRegUsed(DesignatedReg);
- ReusedOperands.markClobbered(DesignatedReg);
- TII->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
-
- MachineInstr *CopyMI = prior(MII);
- UpdateKills(*CopyMI, RegKills, KillOps, TRI);
-
- // This invalidates DesignatedReg.
- Spills.ClobberPhysReg(DesignatedReg);
-
- Spills.addAvailable(ReuseSlot, DesignatedReg);
- unsigned RReg =
- SubIdx ? TRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
- MI.getOperand(i).setReg(RReg);
- DOUT << '\t' << *prior(MII);
- ++NumReused;
- continue;
- } // if (PhysReg)
-
- // Otherwise, reload it and remember that we have it.
- PhysReg = VRM.getPhys(VirtReg);
- assert(PhysReg && "Must map virtreg to physreg!");
-
- // Note that, if we reused a register for a previous operand, the
- // register we want to reload into might not actually be
- // available. If this occurs, use the register indicated by the
- // reuser.
- if (ReusedOperands.hasReuses())
- PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
- Spills, MaybeDeadStores, RegKills, KillOps, VRM);
-
- RegInfo->setPhysRegUsed(PhysReg);
- ReusedOperands.markClobbered(PhysReg);
- if (DoReMat) {
- ReMaterialize(MBB, MII, PhysReg, VirtReg, TII, TRI, VRM);
- } else {
- const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
- TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
- MachineInstr *LoadMI = prior(MII);
- VRM.addSpillSlotUse(SSorRMId, LoadMI);
- ++NumLoads;
- }
- // This invalidates PhysReg.
- Spills.ClobberPhysReg(PhysReg);
-
- // Any stores to this stack slot are not dead anymore.
- if (!DoReMat)
- MaybeDeadStores[SSorRMId] = NULL;
- Spills.addAvailable(SSorRMId, PhysReg);
- // Assumes this is the last use. IsKill will be unset if reg is reused
- // unless it's a two-address operand.
- if (!MI.isRegTiedToDefOperand(i) &&
- KilledMIRegs.count(VirtReg) == 0) {
- MI.getOperand(i).setIsKill();
- KilledMIRegs.insert(VirtReg);
- }
- unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
- MI.getOperand(i).setReg(RReg);
- UpdateKills(*prior(MII), RegKills, KillOps, TRI);
- DOUT << '\t' << *prior(MII);
- }
-
- // Ok - now we can remove stores that have been confirmed dead.
- for (unsigned j = 0, e = PotentialDeadStoreSlots.size(); j != e; ++j) {
- // This was the last use and the spilled value is still available
- // for reuse. That means the spill was unnecessary!
- int PDSSlot = PotentialDeadStoreSlots[j];
- MachineInstr* DeadStore = MaybeDeadStores[PDSSlot];
- if (DeadStore) {
- DOUT << "Removed dead store:\t" << *DeadStore;
- InvalidateKills(*DeadStore, RegKills, KillOps);
- VRM.RemoveMachineInstrFromMaps(DeadStore);
- MBB.erase(DeadStore);
- MaybeDeadStores[PDSSlot] = NULL;
- ++NumDSE;
- }
- }
-
-
- DOUT << '\t' << MI;
-
-
- // If we have folded references to memory operands, make sure we clear all
- // physical registers that may contain the value of the spilled virtual
- // register
- SmallSet<int, 2> FoldedSS;
- for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
- unsigned VirtReg = I->second.first;
- VirtRegMap::ModRef MR = I->second.second;
- DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
-
- // MI2VirtMap be can updated which invalidate the iterator.
- // Increment the iterator first.
- ++I;
- int SS = VRM.getStackSlot(VirtReg);
- if (SS == VirtRegMap::NO_STACK_SLOT)
- continue;
- FoldedSS.insert(SS);
- DOUT << " - StackSlot: " << SS << "\n";
-
- // If this folded instruction is just a use, check to see if it's a
- // straight load from the virt reg slot.
- if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
- int FrameIdx;
- unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx);
- if (DestReg && FrameIdx == SS) {
- // If this spill slot is available, turn it into a copy (or nothing)
- // instead of leaving it as a load!
- if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) {
- DOUT << "Promoted Load To Copy: " << MI;
- if (DestReg != InReg) {
- const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
- TII->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC);
- MachineOperand *DefMO = MI.findRegisterDefOperand(DestReg);
- unsigned SubIdx = DefMO->getSubReg();
- // Revisit the copy so we make sure to notice the effects of the
- // operation on the destreg (either needing to RA it if it's
- // virtual or needing to clobber any values if it's physical).
- NextMII = &MI;
- --NextMII; // backtrack to the copy.
- // Propagate the sub-register index over.
- if (SubIdx) {
- DefMO = NextMII->findRegisterDefOperand(DestReg);
- DefMO->setSubReg(SubIdx);
- }
-
- // Mark is killed.
- MachineOperand *KillOpnd = NextMII->findRegisterUseOperand(InReg);
- KillOpnd->setIsKill();
-
- BackTracked = true;
- } else {
- DOUT << "Removing now-noop copy: " << MI;
- // Unset last kill since it's being reused.
- InvalidateKill(InReg, RegKills, KillOps);
- Spills.disallowClobberPhysReg(InReg);
- }
-
- InvalidateKills(MI, RegKills, KillOps);
- VRM.RemoveMachineInstrFromMaps(&MI);
- MBB.erase(&MI);
- Erased = true;
- goto ProcessNextInst;
- }
- } else {
- unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
- SmallVector<MachineInstr*, 4> NewMIs;
- if (PhysReg &&
- TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
- MBB.insert(MII, NewMIs[0]);
- InvalidateKills(MI, RegKills, KillOps);
- VRM.RemoveMachineInstrFromMaps(&MI);
- MBB.erase(&MI);
- Erased = true;
- --NextMII; // backtrack to the unfolded instruction.
- BackTracked = true;
- goto ProcessNextInst;
- }
- }
- }
-
- // If this reference is not a use, any previous store is now dead.
- // Otherwise, the store to this stack slot is not dead anymore.
- MachineInstr* DeadStore = MaybeDeadStores[SS];
- if (DeadStore) {
- bool isDead = !(MR & VirtRegMap::isRef);
- MachineInstr *NewStore = NULL;
- if (MR & VirtRegMap::isModRef) {
- unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
- SmallVector<MachineInstr*, 4> NewMIs;
- // We can reuse this physreg as long as we are allowed to clobber
- // the value and there isn't an earlier def that has already clobbered
- // the physreg.
- if (PhysReg &&
- !ReusedOperands.isClobbered(PhysReg) &&
- Spills.canClobberPhysReg(PhysReg) &&
- !TII->isStoreToStackSlot(&MI, SS)) { // Not profitable!
- MachineOperand *KillOpnd =
- DeadStore->findRegisterUseOperand(PhysReg, true);
- // Note, if the store is storing a sub-register, it's possible the
- // super-register is needed below.
- if (KillOpnd && !KillOpnd->getSubReg() &&
- TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true,NewMIs)){
- MBB.insert(MII, NewMIs[0]);
- NewStore = NewMIs[1];
- MBB.insert(MII, NewStore);
- VRM.addSpillSlotUse(SS, NewStore);
- InvalidateKills(MI, RegKills, KillOps);
- VRM.RemoveMachineInstrFromMaps(&MI);
- MBB.erase(&MI);
- Erased = true;
- --NextMII;
- --NextMII; // backtrack to the unfolded instruction.
- BackTracked = true;
- isDead = true;
- ++NumSUnfold;
- }
- }
- }
-
- if (isDead) { // Previous store is dead.
- // If we get here, the store is dead, nuke it now.
- DOUT << "Removed dead store:\t" << *DeadStore;
- InvalidateKills(*DeadStore, RegKills, KillOps);
- VRM.RemoveMachineInstrFromMaps(DeadStore);
- MBB.erase(DeadStore);
- if (!NewStore)
- ++NumDSE;
- }
-
- MaybeDeadStores[SS] = NULL;
- if (NewStore) {
- // Treat this store as a spill merged into a copy. That makes the
- // stack slot value available.
- VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod);
- goto ProcessNextInst;
- }
- }
-
- // If the spill slot value is available, and this is a new definition of
- // the value, the value is not available anymore.
- if (MR & VirtRegMap::isMod) {
- // Notice that the value in this stack slot has been modified.
- Spills.ModifyStackSlotOrReMat(SS);
-
- // If this is *just* a mod of the value, check to see if this is just a
- // store to the spill slot (i.e. the spill got merged into the copy). If
- // so, realize that the vreg is available now, and add the store to the
- // MaybeDeadStore info.
- int StackSlot;
- if (!(MR & VirtRegMap::isRef)) {
- if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
- assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
- "Src hasn't been allocated yet?");
-
- if (CommuteToFoldReload(MBB, MII, VirtReg, SrcReg, StackSlot,
- Spills, RegKills, KillOps, TRI, VRM)) {
- NextMII = next(MII);
- BackTracked = true;
- goto ProcessNextInst;
- }
-
- // Okay, this is certainly a store of SrcReg to [StackSlot]. Mark
- // this as a potentially dead store in case there is a subsequent
- // store into the stack slot without a read from it.
- MaybeDeadStores[StackSlot] = &MI;
-
- // If the stack slot value was previously available in some other
- // register, change it now. Otherwise, make the register
- // available in PhysReg.
- Spills.addAvailable(StackSlot, SrcReg, MI.killsRegister(SrcReg));
- }
- }
- }
- }
-
- // Process all of the spilled defs.
- for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI.getOperand(i);
- if (!(MO.isReg() && MO.getReg() && MO.isDef()))
- continue;
-
- unsigned VirtReg = MO.getReg();
- if (!TargetRegisterInfo::isVirtualRegister(VirtReg)) {
- // Check to see if this is a noop copy. If so, eliminate the
- // instruction before considering the dest reg to be changed.
- unsigned Src, Dst, SrcSR, DstSR;
- if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) {
- ++NumDCE;
- DOUT << "Removing now-noop copy: " << MI;
- SmallVector<unsigned, 2> KillRegs;
- InvalidateKills(MI, RegKills, KillOps, &KillRegs);
- if (MO.isDead() && !KillRegs.empty()) {
- // Source register or an implicit super/sub-register use is killed.
- assert(KillRegs[0] == Dst ||
- TRI->isSubRegister(KillRegs[0], Dst) ||
- TRI->isSuperRegister(KillRegs[0], Dst));
- // Last def is now dead.
- TransferDeadness(&MBB, Dist, Src, RegKills, KillOps);
- }
- VRM.RemoveMachineInstrFromMaps(&MI);
- MBB.erase(&MI);
- Erased = true;
- Spills.disallowClobberPhysReg(VirtReg);
- goto ProcessNextInst;
- }
-
- // If it's not a no-op copy, it clobbers the value in the destreg.
- Spills.ClobberPhysReg(VirtReg);
- ReusedOperands.markClobbered(VirtReg);
-
- // Check to see if this instruction is a load from a stack slot into
- // a register. If so, this provides the stack slot value in the reg.
- int FrameIdx;
- if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
- assert(DestReg == VirtReg && "Unknown load situation!");
-
- // If it is a folded reference, then it's not safe to clobber.
- bool Folded = FoldedSS.count(FrameIdx);
- // Otherwise, if it wasn't available, remember that it is now!
- Spills.addAvailable(FrameIdx, DestReg, !Folded);
- goto ProcessNextInst;
- }
-
- continue;
- }
-
- unsigned SubIdx = MO.getSubReg();
- bool DoReMat = VRM.isReMaterialized(VirtReg);
- if (DoReMat)
- ReMatDefs.insert(&MI);
-
- // The only vregs left are stack slot definitions.
- int StackSlot = VRM.getStackSlot(VirtReg);
- const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
-
- // If this def is part of a two-address operand, make sure to execute
- // the store from the correct physical register.
- unsigned PhysReg;
- int TiedOp = MI.getDesc().findTiedToSrcOperand(i);
- if (TiedOp != -1) {
- PhysReg = MI.getOperand(TiedOp).getReg();
- if (SubIdx) {
- unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, TRI);
- assert(SuperReg && TRI->getSubReg(SuperReg, SubIdx) == PhysReg &&
- "Can't find corresponding super-register!");
- PhysReg = SuperReg;
- }
- } else {
- PhysReg = VRM.getPhys(VirtReg);
- if (ReusedOperands.isClobbered(PhysReg)) {
- // Another def has taken the assigned physreg. It must have been a
- // use&def which got it due to reuse. Undo the reuse!
- PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
- Spills, MaybeDeadStores, RegKills, KillOps, VRM);
- }
- }
-
- assert(PhysReg && "VR not assigned a physical register?");
- RegInfo->setPhysRegUsed(PhysReg);
- unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
- ReusedOperands.markClobbered(RReg);
- MI.getOperand(i).setReg(RReg);
-
- if (!MO.isDead()) {
- MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
- SpillRegToStackSlot(MBB, MII, -1, PhysReg, StackSlot, RC, true,
- LastStore, Spills, ReMatDefs, RegKills, KillOps, VRM);
- NextMII = next(MII);
-
- // Check to see if this is a noop copy. If so, eliminate the
- // instruction before considering the dest reg to be changed.
- {
- unsigned Src, Dst, SrcSR, DstSR;
- if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) {
- ++NumDCE;
- DOUT << "Removing now-noop copy: " << MI;
- InvalidateKills(MI, RegKills, KillOps);
- VRM.RemoveMachineInstrFromMaps(&MI);
- MBB.erase(&MI);
- Erased = true;
- UpdateKills(*LastStore, RegKills, KillOps, TRI);
- goto ProcessNextInst;
- }
- }
- }
- }
- ProcessNextInst:
- DistanceMap.insert(std::make_pair(&MI, Dist++));
- if (!Erased && !BackTracked) {
- for (MachineBasicBlock::iterator II = &MI; II != NextMII; ++II)
- UpdateKills(*II, RegKills, KillOps, TRI);
- }
- MII = NextMII;
- }
-
-}