//===----------------------------------------------------------------------===//
namespace {
+ class AvailableSpills;
+
/// LocalSpiller - This spiller does a simple pass over the machine basic
/// block to attempt to keep spills in registers as much as possible for
/// blocks that have low register pressure (the vreg may be spilled due to
return true;
}
private:
+ bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator &MII,
+ std::vector<MachineInstr*> &MaybeDeadStores,
+ AvailableSpills &Spills, BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ VirtRegMap &VRM);
void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM);
};
}
void disallowClobberPhysReg(unsigned PhysReg);
/// ClobberPhysReg - This is called when the specified physreg changes
- /// value. We use this to invalidate any info about stuff we thing lives in
+ /// value. We use this to invalidate any info about stuff that lives in
/// it and any of its aliases.
void ClobberPhysReg(unsigned PhysReg);
/// marked kill, then invalidate the information.
static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
std::vector<MachineOperand*> &KillOps,
- SmallVector<unsigned, 1> *KillRegs = NULL) {
+ SmallVector<unsigned, 2> *KillRegs = NULL) {
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI.getOperand(i);
if (!MO.isRegister() || !MO.isUse() || !MO.isKill())
};
}
+/// PrepForUnfoldOpti - Turn a store folding instruction into a load folding
+/// instruction. e.g.
+/// xorl %edi, %eax
+/// movl %eax, -32(%ebp)
+/// movl -36(%ebp), %eax
+/// orl %eax, -32(%ebp)
+/// ==>
+/// xorl %edi, %eax
+/// orl -36(%ebp), %eax
+/// mov %eax, -32(%ebp)
+/// This enables unfolding optimization for a subsequent instruction which will
+/// also eliminate the newly introduced store instruction.
+bool LocalSpiller::PrepForUnfoldOpti(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator &MII,
+ std::vector<MachineInstr*> &MaybeDeadStores,
+ AvailableSpills &Spills,
+ BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ VirtRegMap &VRM) {
+ MachineFunction &MF = *MBB.getParent();
+ MachineInstr &MI = *MII;
+ unsigned UnfoldedOpc = 0;
+ unsigned UnfoldPR = 0;
+ unsigned UnfoldVR = 0;
+ int FoldedSS = VirtRegMap::NO_STACK_SLOT;
+ VirtRegMap::MI2VirtMapTy::const_iterator I, End;
+ for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
+ // Only transform a MI that folds a single register.
+ if (UnfoldedOpc)
+ return false;
+ UnfoldVR = I->second.first;
+ VirtRegMap::ModRef MR = I->second.second;
+ if (VRM.isAssignedReg(UnfoldVR))
+ continue;
+ // If this reference is not a use, any previous store is now dead.
+ // Otherwise, the store to this stack slot is not dead anymore.
+ FoldedSS = VRM.getStackSlot(UnfoldVR);
+ MachineInstr* DeadStore = MaybeDeadStores[FoldedSS];
+ if (DeadStore && (MR & VirtRegMap::isModRef)) {
+ unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(FoldedSS);
+ if (!PhysReg ||
+ DeadStore->findRegisterUseOperandIdx(PhysReg, true) == -1)
+ continue;
+ UnfoldPR = PhysReg;
+ UnfoldedOpc = MRI->getOpcodeAfterMemoryUnfold(MI.getOpcode(),
+ false, true);
+ }
+ }
+
+ if (!UnfoldedOpc)
+ return false;
+
+ for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI.getOperand(i);
+ if (!MO.isRegister() || MO.getReg() == 0 || !MO.isUse())
+ continue;
+ unsigned VirtReg = MO.getReg();
+ if (MRegisterInfo::isPhysicalRegister(VirtReg) || MO.getSubReg())
+ continue;
+ if (VRM.isAssignedReg(VirtReg)) {
+ unsigned PhysReg = VRM.getPhys(VirtReg);
+ if (PhysReg && MRI->regsOverlap(PhysReg, UnfoldPR))
+ return false;
+ } else if (VRM.isReMaterialized(VirtReg))
+ continue;
+ int SS = VRM.getStackSlot(VirtReg);
+ unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
+ if (PhysReg) {
+ if (MRI->regsOverlap(PhysReg, UnfoldPR))
+ return false;
+ continue;
+ }
+ PhysReg = VRM.getPhys(VirtReg);
+ if (!MRI->regsOverlap(PhysReg, UnfoldPR))
+ continue;
+
+ // Ok, we'll need to reload the value into a register which makes
+ // it impossible to perform the store unfolding optimization later.
+ // Let's see if it is possible to fold the load if the store is
+ // unfolded. This allows us to perform the store unfolding
+ // optimization.
+ SmallVector<MachineInstr*, 4> NewMIs;
+ if (MRI->unfoldMemoryOperand(MF, &MI, UnfoldVR, false, false, NewMIs)) {
+ assert(NewMIs.size() == 1);
+ MachineInstr *NewMI = NewMIs.back();
+ NewMIs.clear();
+ unsigned Idx = NewMI->findRegisterUseOperandIdx(VirtReg);
+ MachineInstr *FoldedMI = MRI->foldMemoryOperand(NewMI, Idx, SS);
+ if (FoldedMI) {
+ if (!VRM.hasPhys(UnfoldVR))
+ VRM.assignVirt2Phys(UnfoldVR, UnfoldPR);
+ VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
+ MII = MBB.insert(MII, FoldedMI);
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ MBB.erase(&MI);
+ return true;
+ }
+ delete NewMI;
+ }
+ }
+ return false;
+}
+
+/// findSuperReg - Find the SubReg's super-register of given register class
+/// where its SubIdx sub-register is SubReg.
+static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg,
+ unsigned SubIdx, const MRegisterInfo *MRI) {
+ for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
+ I != E; ++I) {
+ unsigned Reg = *I;
+ if (MRI->getSubReg(Reg, SubIdx) == SubReg)
+ return Reg;
+ }
+ return 0;
+}
/// rewriteMBB - Keep track of which spills are available even after the
/// register allocator is done with them. If possible, avoid reloading vregs.
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
MII != E; ) {
- MachineInstr &MI = *MII;
MachineBasicBlock::iterator NextMII = MII; ++NextMII;
- VirtRegMap::MI2VirtMapTy::const_iterator I, End;
+ VirtRegMap::MI2VirtMapTy::const_iterator I, End;
bool Erased = false;
bool BackTracked = false;
+ if (PrepForUnfoldOpti(MBB, MII,
+ MaybeDeadStores, Spills, RegKills, KillOps, VRM))
+ NextMII = next(MII);
/// ReusedOperands - Keep track of operand reuse in case we need to undo
/// reuse.
+ MachineInstr &MI = *MII;
ReuseInfo ReusedOperands(MI, MRI);
- // Loop over all of the implicit defs, clearing them from our available
- // sets.
const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
- if (TID->ImplicitDefs) {
- const unsigned *ImpDef = TID->ImplicitDefs;
- for ( ; *ImpDef; ++ImpDef) {
- MF.setPhysRegUsed(*ImpDef);
- ReusedOperands.markClobbered(*ImpDef);
- Spills.ClobberPhysReg(*ImpDef);
- }
- }
// Process all of the spilled uses and all non spilled reg references.
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
// Ignore physregs for spilling, but remember that it is used by this
// function.
MF.setPhysRegUsed(VirtReg);
- ReusedOperands.markClobbered(VirtReg);
continue;
}
assert(MRegisterInfo::isVirtualRegister(VirtReg) &&
"Not a virtual or a physical register?");
- unsigned SubIdx = 0;
- bool isSubReg = RegMap->isSubRegister(VirtReg);
- if (isSubReg) {
- SubIdx = RegMap->getSubRegisterIndex(VirtReg);
- VirtReg = RegMap->getSuperRegister(VirtReg);
- }
-
+ unsigned SubIdx = MO.getSubReg();
if (VRM.isAssignedReg(VirtReg)) {
// This virtual register was assigned a physreg!
unsigned Phys = VRM.getPhys(VirtReg);
MF.setPhysRegUsed(Phys);
if (MO.isDef())
ReusedOperands.markClobbered(Phys);
- unsigned RReg = isSubReg ? MRI->getSubReg(Phys, SubIdx) : Phys;
+ unsigned RReg = SubIdx ? MRI->getSubReg(Phys, SubIdx) : Phys;
MI.getOperand(i).setReg(RReg);
continue;
}
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
if (!PhysReg && DoReMat) {
// This use is rematerializable. But perhaps the value is available in
- // stack if the definition is not deleted. If so, check if we can
+ // a register if the definition is not deleted. If so, check if we can
// reuse the value.
ReuseSlot = VRM.getStackSlot(VirtReg);
if (ReuseSlot != VirtRegMap::NO_STACK_SLOT)
// fi#1 is available in EDI, but it cannot be reused because it's not in
// the right register file.
if (PhysReg &&
- (isSubReg || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
+ (SubIdx || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
if (!RC->contains(PhysReg))
PhysReg = 0;
// aren't allowed to modify the reused register. If none of these cases
// apply, reuse it.
bool CanReuse = true;
-
int ti = TID->getOperandConstraint(i, TOI::TIED_TO);
if (ti != -1 &&
MI.getOperand(ti).isRegister() &&
<< MRI->getName(PhysReg) << " for vreg"
<< VirtReg <<" instead of reloading into physreg "
<< MRI->getName(VRM.getPhys(VirtReg)) << "\n";
- unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
+ unsigned RReg = SubIdx ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
MI.getOperand(i).setReg(RReg);
// The only technical detail we have is that we don't know that
if (DeadStore) {
DOUT << "Removed dead store:\t" << *DeadStore;
InvalidateKills(*DeadStore, RegKills, KillOps);
- MBB.erase(DeadStore);
VRM.RemoveFromFoldedVirtMap(DeadStore);
+ MBB.erase(DeadStore);
MaybeDeadStores[ReuseSlot] = NULL;
++NumDSE;
}
DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg"
<< VirtReg
<< " instead of reloading into same physreg.\n";
- unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
+ unsigned RReg = SubIdx ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
MI.getOperand(i).setReg(RReg);
- ReusedOperands.markClobbered(PhysReg);
+ ReusedOperands.markClobbered(RReg);
++NumReused;
continue;
}
Spills.addAvailable(ReuseSlot, &MI, DesignatedReg);
unsigned RReg =
- isSubReg ? MRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
+ SubIdx ? MRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
MI.getOperand(i).setReg(RReg);
DOUT << '\t' << *prior(MII);
++NumReused;
continue;
- } // is (PhysReg)
+ } // if (PhysReg)
// Otherwise, reload it and remember that we have it.
PhysReg = VRM.getPhys(VirtReg);
// unless it's a two-address operand.
if (TID->getOperandConstraint(i, TOI::TIED_TO) == -1)
MI.getOperand(i).setIsKill();
- unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
+ unsigned RReg = SubIdx ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
MI.getOperand(i).setReg(RReg);
UpdateKills(*prior(MII), RegKills, KillOps);
DOUT << '\t' << *prior(MII);
// 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, 1> FoldedSS;
+ SmallSet<int, 2> FoldedSS;
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
- DOUT << "Folded vreg: " << I->second.first << " MR: "
- << I->second.second;
unsigned VirtReg = I->second.first;
VirtRegMap::ModRef MR = I->second.second;
+ DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
if (VRM.isAssignedReg(VirtReg)) {
DOUT << ": No stack slot!\n";
continue;
// Otherwise, the store to this stack slot is not dead anymore.
MachineInstr* DeadStore = MaybeDeadStores[SS];
if (DeadStore) {
- bool isDead = true;
+ bool isDead = !(MR & VirtRegMap::isRef);
MachineInstr *NewStore = NULL;
- if (MR & VirtRegMap::isRef) {
+ if (MR & VirtRegMap::isModRef) {
unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
SmallVector<MachineInstr*, 4> NewMIs;
if (PhysReg &&
--NextMII;
--NextMII; // backtrack to the unfolded instruction.
BackTracked = true;
- } else
- isDead = false;
+ isDead = true;
+ }
}
if (isDead) { // Previous store is dead.
// Process all of the spilled defs.
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI.getOperand(i);
- if (MO.isRegister() && MO.getReg() && MO.isDef()) {
- unsigned VirtReg = MO.getReg();
+ if (!(MO.isRegister() && MO.getReg() && MO.isDef()))
+ continue;
- if (!MRegisterInfo::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;
- if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
- ++NumDCE;
- DOUT << "Removing now-noop copy: " << MI;
- MBB.erase(&MI);
- Erased = true;
- VRM.RemoveFromFoldedVirtMap(&MI);
- Spills.disallowClobberPhysReg(VirtReg);
- goto ProcessNextInst;
- }
+ unsigned VirtReg = MO.getReg();
+ if (!MRegisterInfo::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;
+ if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
+ ++NumDCE;
+ DOUT << "Removing now-noop copy: " << MI;
+ MBB.erase(&MI);
+ Erased = true;
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ 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);
+ // 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, &MI, DestReg, !Folded);
- goto ProcessNextInst;
- }
-
- continue;
+ // 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, &MI, DestReg, !Folded);
+ goto ProcessNextInst;
}
+
+ continue;
+ }
- 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 = RegMap->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.getInstrDescriptor()->findTiedToSrcOperand(i);
- if (TiedOp != -1)
- PhysReg = MI.getOperand(TiedOp).getReg();
- 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,
+ 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 = RegMap->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.getInstrDescriptor()->findTiedToSrcOperand(i);
+ if (TiedOp != -1) {
+ PhysReg = MI.getOperand(TiedOp).getReg();
+ if (SubIdx) {
+ unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, MRI);
+ assert(SuperReg && MRI->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);
- }
}
+ }
- MF.setPhysRegUsed(PhysReg);
- ReusedOperands.markClobbered(PhysReg);
- MI.getOperand(i).setReg(PhysReg);
- if (!MO.isDead()) {
- MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
- DOUT << "Store:\t" << *next(MII);
-
- // If there is a dead store to this stack slot, nuke it now.
- MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
- if (LastStore) {
- DOUT << "Removed dead store:\t" << *LastStore;
- ++NumDSE;
- SmallVector<unsigned, 1> KillRegs;
- InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
- MachineBasicBlock::iterator PrevMII = LastStore;
- bool CheckDef = PrevMII != MBB.begin();
- if (CheckDef)
- --PrevMII;
- MBB.erase(LastStore);
- VRM.RemoveFromFoldedVirtMap(LastStore);
- if (CheckDef) {
- // Look at defs of killed registers on the store. Mark the defs
- // as dead since the store has been deleted and they aren't
- // being reused.
- for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
- bool HasOtherDef = false;
- if (InvalidateRegDef(PrevMII, MI, KillRegs[j], HasOtherDef)) {
- MachineInstr *DeadDef = PrevMII;
- if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
- // FIXME: This assumes a remat def does not have side
- // effects.
- MBB.erase(DeadDef);
- VRM.RemoveFromFoldedVirtMap(DeadDef);
- ++NumDRM;
- }
+ MF.setPhysRegUsed(PhysReg);
+ unsigned RReg = SubIdx ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
+ ReusedOperands.markClobbered(RReg);
+ MI.getOperand(i).setReg(RReg);
+
+ if (!MO.isDead()) {
+ MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
+ DOUT << "Store:\t" << *next(MII);
+
+ // If there is a dead store to this stack slot, nuke it now.
+ MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
+ if (LastStore) {
+ DOUT << "Removed dead store:\t" << *LastStore;
+ ++NumDSE;
+ SmallVector<unsigned, 2> KillRegs;
+ InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
+ MachineBasicBlock::iterator PrevMII = LastStore;
+ bool CheckDef = PrevMII != MBB.begin();
+ if (CheckDef)
+ --PrevMII;
+ MBB.erase(LastStore);
+ VRM.RemoveFromFoldedVirtMap(LastStore);
+ if (CheckDef) {
+ // Look at defs of killed registers on the store. Mark the defs
+ // as dead since the store has been deleted and they aren't
+ // being reused.
+ for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
+ bool HasOtherDef = false;
+ if (InvalidateRegDef(PrevMII, MI, KillRegs[j], HasOtherDef)) {
+ MachineInstr *DeadDef = PrevMII;
+ if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
+ // FIXME: This assumes a remat def does not have side
+ // effects.
+ MBB.erase(DeadDef);
+ VRM.RemoveFromFoldedVirtMap(DeadDef);
+ ++NumDRM;
}
}
}
}
- LastStore = next(MII);
-
- // If the stack slot value was previously available in some other
- // register, change it now. Otherwise, make the register available,
- // in PhysReg.
- Spills.ModifyStackSlotOrReMat(StackSlot);
- Spills.ClobberPhysReg(PhysReg);
- Spills.addAvailable(StackSlot, LastStore, PhysReg);
- ++NumStores;
-
- // 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;
- if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
- ++NumDCE;
- DOUT << "Removing now-noop copy: " << MI;
- MBB.erase(&MI);
- Erased = true;
- VRM.RemoveFromFoldedVirtMap(&MI);
- UpdateKills(*LastStore, RegKills, KillOps);
- goto ProcessNextInst;
- }
+ }
+ LastStore = next(MII);
+
+ // If the stack slot value was previously available in some other
+ // register, change it now. Otherwise, make the register available,
+ // in PhysReg.
+ Spills.ModifyStackSlotOrReMat(StackSlot);
+ Spills.ClobberPhysReg(PhysReg);
+ Spills.addAvailable(StackSlot, LastStore, PhysReg);
+ ++NumStores;
+
+ // 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;
+ if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
+ ++NumDCE;
+ DOUT << "Removing now-noop copy: " << MI;
+ MBB.erase(&MI);
+ Erased = true;
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ UpdateKills(*LastStore, RegKills, KillOps);
+ goto ProcessNextInst;
}
- }
- }
+ }
+ }
}
ProcessNextInst:
if (!Erased && !BackTracked)
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