X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FVirtRegMap.cpp;h=ebdbb86c2bdda896a4ae5d03a6f2c5b751e8e9f5;hb=32dfbeada7292167bb488f36a71a5a6a519ddaff;hp=1f9c1649d449f10e7f54f2aa12ff6d79be202fc9;hpb=82a87a01723c095176c6940bcc63d3a7c8007b4b;p=oota-llvm.git diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp index 1f9c1649d44..ebdbb86c2bd 100644 --- a/lib/CodeGen/VirtRegMap.cpp +++ b/lib/CodeGen/VirtRegMap.cpp @@ -36,6 +36,7 @@ using namespace llvm; STATISTIC(NumSpills, "Number of register spills"); STATISTIC(NumReMats, "Number of re-materialization"); +STATISTIC(NumDRM , "Number of re-materializable defs elided"); STATISTIC(NumStores, "Number of stores added"); STATISTIC(NumLoads , "Number of loads added"); STATISTIC(NumReused, "Number of values reused"); @@ -62,13 +63,17 @@ namespace { VirtRegMap::VirtRegMap(MachineFunction &mf) : TII(*mf.getTarget().getInstrInfo()), MF(mf), Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT), + Virt2ReMatIdMap(NO_STACK_SLOT), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1) { grow(); } void VirtRegMap::grow() { - Virt2PhysMap.grow(MF.getSSARegMap()->getLastVirtReg()); - Virt2StackSlotMap.grow(MF.getSSARegMap()->getLastVirtReg()); + unsigned LastVirtReg = MF.getSSARegMap()->getLastVirtReg(); + Virt2PhysMap.grow(LastVirtReg); + Virt2StackSlotMap.grow(LastVirtReg); + Virt2ReMatIdMap.grow(LastVirtReg); + ReMatMap.grow(LastVirtReg); } int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) { @@ -95,19 +100,19 @@ void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex) { int VirtRegMap::assignVirtReMatId(unsigned virtReg) { assert(MRegisterInfo::isVirtualRegister(virtReg)); - assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT && + assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT && "attempt to assign re-mat id to already spilled register"); - const MachineInstr *DefMI = getReMaterializedMI(virtReg); - int FrameIdx; - if (TII.isLoadFromStackSlot((MachineInstr*)DefMI, FrameIdx)) { - // Load from stack slot is re-materialize as reload from the stack slot! - Virt2StackSlotMap[virtReg] = FrameIdx; - return FrameIdx; - } - Virt2StackSlotMap[virtReg] = ReMatId; + Virt2ReMatIdMap[virtReg] = ReMatId; return ReMatId++; } +void VirtRegMap::assignVirtReMatId(unsigned virtReg, int id) { + assert(MRegisterInfo::isVirtualRegister(virtReg)); + assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT && + "attempt to assign re-mat id to already spilled register"); + Virt2ReMatIdMap[virtReg] = id; +} + void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI, unsigned OpNo, MachineInstr *NewMI) { // Move previous memory references folded to new instruction. @@ -194,7 +199,7 @@ bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) { if (MRegisterInfo::isVirtualRegister(MO.getReg())) { unsigned VirtReg = MO.getReg(); unsigned PhysReg = VRM.getPhys(VirtReg); - if (VRM.hasStackSlot(VirtReg)) { + if (!VRM.isAssignedReg(VirtReg)) { int StackSlot = VRM.getStackSlot(VirtReg); const TargetRegisterClass* RC = MF.getSSARegMap()->getRegClass(VirtReg); @@ -237,54 +242,58 @@ namespace { /// blocks that have low register pressure (the vreg may be spilled due to /// register pressure in other blocks). class VISIBILITY_HIDDEN LocalSpiller : public Spiller { + SSARegMap *RegMap; const MRegisterInfo *MRI; const TargetInstrInfo *TII; public: bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) { + RegMap = MF.getSSARegMap(); MRI = MF.getTarget().getRegisterInfo(); TII = MF.getTarget().getInstrInfo(); DOUT << "\n**** Local spiller rewriting function '" << MF.getFunction()->getName() << "':\n"; + DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!) ****\n"; + DEBUG(MF.dump()); - std::vector ReMatedMIs; for (MachineFunction::iterator MBB = MF.begin(), E = MF.end(); MBB != E; ++MBB) - RewriteMBB(*MBB, VRM, ReMatedMIs); - for (unsigned i = 0, e = ReMatedMIs.size(); i != e; ++i) - delete ReMatedMIs[i]; + RewriteMBB(*MBB, VRM); + + DOUT << "**** Post Machine Instrs ****\n"; + DEBUG(MF.dump()); + return true; } private: - void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, - std::vector &ReMatedMIs); + void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM); }; } /// AvailableSpills - As the local spiller is scanning and rewriting an MBB from -/// top down, keep track of which spills slots are available in each register. +/// top down, keep track of which spills slots or remat are available in each +/// register. /// /// Note that not all physregs are created equal here. In particular, some /// physregs are reloads that we are allowed to clobber or ignore at any time. /// Other physregs are values that the register allocated program is using that /// we cannot CHANGE, but we can read if we like. We keep track of this on a -/// per-stack-slot basis as the low bit in the value of the SpillSlotsAvailable -/// entries. The predicate 'canClobberPhysReg()' checks this bit and -/// addAvailable sets it if. +/// per-stack-slot / remat id basis as the low bit in the value of the +/// SpillSlotsAvailable entries. The predicate 'canClobberPhysReg()' checks +/// this bit and addAvailable sets it if. namespace { class VISIBILITY_HIDDEN AvailableSpills { const MRegisterInfo *MRI; const TargetInstrInfo *TII; - // SpillSlotsAvailable - This map keeps track of all of the spilled virtual - // register values that are still available, due to being loaded or stored to, - // but not invalidated yet. It also tracks the instructions that defined - // or used the register. - typedef std::pair > SSInfo; - std::map SpillSlotsAvailable; + // SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled + // or remat'ed virtual register values that are still available, due to being + // loaded or stored to, but not invalidated yet. + std::map SpillSlotsOrReMatsAvailable; - // PhysRegsAvailable - This is the inverse of SpillSlotsAvailable, indicating - // which stack slot values are currently held by a physreg. This is used to - // invalidate entries in SpillSlotsAvailable when a physreg is modified. + // PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable, + // indicating which stack slot values are currently held by a physreg. This + // is used to invalidate entries in SpillSlotsOrReMatsAvailable when a + // physreg is modified. std::multimap PhysRegsAvailable; void disallowClobberPhysRegOnly(unsigned PhysReg); @@ -297,85 +306,44 @@ public: const MRegisterInfo *getRegInfo() const { return MRI; } - /// getSpillSlotPhysReg - If the specified stack slot is available in a - /// physical register, return that PhysReg, otherwise return 0. It also - /// returns by reference the instruction that either defines or last uses - /// the register. - unsigned getSpillSlotPhysReg(int Slot, MachineInstr *&SSMI) const { - std::map::const_iterator I = SpillSlotsAvailable.find(Slot); - if (I != SpillSlotsAvailable.end()) { - if (!I->second.second.empty()) - SSMI = I->second.second.back(); - return I->second.first >> 1; // Remove the CanClobber bit. + /// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is + /// available in a physical register, return that PhysReg, otherwise + /// return 0. + unsigned getSpillSlotOrReMatPhysReg(int Slot) const { + std::map::const_iterator I = + SpillSlotsOrReMatsAvailable.find(Slot); + if (I != SpillSlotsOrReMatsAvailable.end()) { + return I->second >> 1; // Remove the CanClobber bit. } return 0; } - /// addLastUse - Add the last use information of all stack slots whose - /// values are available in the specific register. - void addLastUse(unsigned PhysReg, MachineInstr *Use) { - std::multimap::iterator I = - PhysRegsAvailable.lower_bound(PhysReg); - while (I != PhysRegsAvailable.end() && I->first == PhysReg) { - int Slot = I->second; - I++; - - std::map::iterator II = SpillSlotsAvailable.find(Slot); - assert(II != SpillSlotsAvailable.end() && "Slot not available!"); - unsigned Val = II->second.first; - assert((Val >> 1) == PhysReg && "Bidirectional map mismatch!"); - // This can be true if there are multiple uses of the same register. - if (II->second.second.back() != Use) - II->second.second.push_back(Use); - } - } - - /// removeLastUse - Remove the last use information of all stack slots whose - /// values are available in the specific register. - void removeLastUse(unsigned PhysReg, MachineInstr *Use) { - std::multimap::iterator I = - PhysRegsAvailable.lower_bound(PhysReg); - while (I != PhysRegsAvailable.end() && I->first == PhysReg) { - int Slot = I->second; - I++; - - std::map::iterator II = SpillSlotsAvailable.find(Slot); - assert(II != SpillSlotsAvailable.end() && "Slot not available!"); - unsigned Val = II->second.first; - assert((Val >> 1) == PhysReg && "Bidirectional map mismatch!"); - if (II->second.second.back() == Use) - II->second.second.pop_back(); - } - } - - /// addAvailable - Mark that the specified stack slot is available in the - /// specified physreg. If CanClobber is true, the physreg can be modified at - /// any time without changing the semantics of the program. - void addAvailable(int Slot, MachineInstr *MI, unsigned Reg, + /// addAvailable - Mark that the specified stack slot / remat is available in + /// the specified physreg. If CanClobber is true, the physreg can be modified + /// at any time without changing the semantics of the program. + void addAvailable(int SlotOrReMat, MachineInstr *MI, unsigned Reg, bool CanClobber = true) { // If this stack slot is thought to be available in some other physreg, // remove its record. - ModifyStackSlot(Slot); + ModifyStackSlotOrReMat(SlotOrReMat); - PhysRegsAvailable.insert(std::make_pair(Reg, Slot)); - std::vector DefUses; - DefUses.push_back(MI); - SpillSlotsAvailable[Slot] = - std::make_pair((Reg << 1) | (unsigned)CanClobber, DefUses); + PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat)); + SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber; - if (Slot > VirtRegMap::MAX_STACK_SLOT) - DOUT << "Remembering RM#" << Slot-VirtRegMap::MAX_STACK_SLOT-1; + if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT) + DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1; else - DOUT << "Remembering SS#" << Slot; + DOUT << "Remembering SS#" << SlotOrReMat; DOUT << " in physreg " << MRI->getName(Reg) << "\n"; } /// canClobberPhysReg - Return true if the spiller is allowed to change the /// value of the specified stackslot register if it desires. The specified /// stack slot must be available in a physreg for this query to make sense. - bool canClobberPhysReg(int Slot) const { - assert(SpillSlotsAvailable.count(Slot) && "Slot not available!"); - return SpillSlotsAvailable.find(Slot)->second.first & 1; + bool canClobberPhysReg(int SlotOrReMat) const { + assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) && + "Value not available!"); + return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1; } /// disallowClobberPhysReg - Unset the CanClobber bit of the specified @@ -388,10 +356,10 @@ public: /// it and any of its aliases. void ClobberPhysReg(unsigned PhysReg); - /// ModifyStackSlot - This method is called when the value in a stack slot - /// changes. This removes information about which register the previous value - /// for this slot lives in (as the previous value is dead now). - void ModifyStackSlot(int Slot); + /// ModifyStackSlotOrReMat - This method is called when the value in a stack + /// slot changes. This removes information about which register the previous + /// value for this slot lives in (as the previous value is dead now). + void ModifyStackSlotOrReMat(int SlotOrReMat); }; } @@ -402,11 +370,11 @@ void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) { std::multimap::iterator I = PhysRegsAvailable.lower_bound(PhysReg); while (I != PhysRegsAvailable.end() && I->first == PhysReg) { - int Slot = I->second; + int SlotOrReMat = I->second; I++; - assert((SpillSlotsAvailable[Slot].first >> 1) == PhysReg && + assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg && "Bidirectional map mismatch!"); - SpillSlotsAvailable[Slot].first &= ~1; + SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1; DOUT << "PhysReg " << MRI->getName(PhysReg) << " copied, it is available for use but can no longer be modified\n"; } @@ -427,17 +395,17 @@ void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) { std::multimap::iterator I = PhysRegsAvailable.lower_bound(PhysReg); while (I != PhysRegsAvailable.end() && I->first == PhysReg) { - int Slot = I->second; + int SlotOrReMat = I->second; PhysRegsAvailable.erase(I++); - assert((SpillSlotsAvailable[Slot].first >> 1) == PhysReg && + assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg && "Bidirectional map mismatch!"); - SpillSlotsAvailable.erase(Slot); + SpillSlotsOrReMatsAvailable.erase(SlotOrReMat); DOUT << "PhysReg " << MRI->getName(PhysReg) << " clobbered, invalidating "; - if (Slot > VirtRegMap::MAX_STACK_SLOT) - DOUT << "RM#" << Slot-VirtRegMap::MAX_STACK_SLOT-1 << "\n"; + if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT) + DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n"; else - DOUT << "SS#" << Slot << "\n"; + DOUT << "SS#" << SlotOrReMat << "\n"; } } @@ -450,14 +418,15 @@ void AvailableSpills::ClobberPhysReg(unsigned PhysReg) { ClobberPhysRegOnly(PhysReg); } -/// ModifyStackSlot - This method is called when the value in a stack slot -/// changes. This removes information about which register the previous value -/// for this slot lives in (as the previous value is dead now). -void AvailableSpills::ModifyStackSlot(int Slot) { - std::map::iterator It = SpillSlotsAvailable.find(Slot); - if (It == SpillSlotsAvailable.end()) return; - unsigned Reg = It->second.first >> 1; - SpillSlotsAvailable.erase(It); +/// ModifyStackSlotOrReMat - This method is called when the value in a stack +/// slot changes. This removes information about which register the previous +/// value for this slot lives in (as the previous value is dead now). +void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) { + std::map::iterator It = + SpillSlotsOrReMatsAvailable.find(SlotOrReMat); + if (It == SpillSlotsOrReMatsAvailable.end()) return; + unsigned Reg = It->second >> 1; + SpillSlotsOrReMatsAvailable.erase(It); // This register may hold the value of multiple stack slots, only remove this // stack slot from the set of values the register contains. @@ -465,13 +434,118 @@ void AvailableSpills::ModifyStackSlot(int Slot) { for (; ; ++I) { assert(I != PhysRegsAvailable.end() && I->first == Reg && "Map inverse broken!"); - if (I->second == Slot) break; + if (I->second == SlotOrReMat) break; } PhysRegsAvailable.erase(I); } +/// InvalidateKills - MI is going to be deleted. If any of its operands are +/// marked kill, then invalidate the information. +static void InvalidateKills(MachineInstr &MI, BitVector &RegKills, + std::vector &KillOps, + SmallVector *KillRegs = NULL) { + for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { + MachineOperand &MO = MI.getOperand(i); + if (!MO.isRegister() || !MO.isUse() || !MO.isKill()) + continue; + unsigned Reg = MO.getReg(); + if (KillRegs) + KillRegs->push_back(Reg); + if (KillOps[Reg] == &MO) { + RegKills.reset(Reg); + KillOps[Reg] = NULL; + } + } +} + +/// InvalidateRegDef - If the def operand of the specified def MI is now dead +/// (since it's spill instruction is removed), mark it isDead. Also checks if +/// the def MI has other definition operands that are not dead. Returns it by +/// reference. +static bool InvalidateRegDef(MachineBasicBlock::iterator I, + MachineInstr &NewDef, unsigned Reg, + bool &HasLiveDef) { + // Due to remat, it's possible this reg isn't being reused. That is, + // the def of this reg (by prev MI) is now dead. + MachineInstr *DefMI = I; + MachineOperand *DefOp = NULL; + for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) { + MachineOperand &MO = DefMI->getOperand(i); + if (MO.isRegister() && MO.isDef()) { + if (MO.getReg() == Reg) + DefOp = &MO; + else if (!MO.isDead()) + HasLiveDef = true; + } + } + if (!DefOp) + return false; + + bool FoundUse = false, Done = false; + MachineBasicBlock::iterator E = NewDef; + ++I; ++E; + for (; !Done && I != E; ++I) { + MachineInstr *NMI = I; + for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) { + MachineOperand &MO = NMI->getOperand(j); + if (!MO.isRegister() || MO.getReg() != Reg) + continue; + if (MO.isUse()) + FoundUse = true; + Done = true; // Stop after scanning all the operands of this MI. + } + } + if (!FoundUse) { + // Def is dead! + DefOp->setIsDead(); + return true; + } + return false; +} + +/// UpdateKills - Track and update kill info. If a MI reads a register that is +/// marked kill, then it must be due to register reuse. Transfer the kill info +/// over. +static void UpdateKills(MachineInstr &MI, BitVector &RegKills, + std::vector &KillOps) { + const TargetInstrDescriptor *TID = MI.getInstrDescriptor(); + for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { + MachineOperand &MO = MI.getOperand(i); + if (!MO.isRegister() || !MO.isUse()) + continue; + unsigned Reg = MO.getReg(); + if (Reg == 0) + continue; + + if (RegKills[Reg]) { + // That can't be right. Register is killed but not re-defined and it's + // being reused. Let's fix that. + KillOps[Reg]->unsetIsKill(); + if (i < TID->numOperands && + TID->getOperandConstraint(i, TOI::TIED_TO) == -1) + // Unless it's a two-address operand, this is the new kill. + MO.setIsKill(); + } + + if (MO.isKill()) { + RegKills.set(Reg); + KillOps[Reg] = &MO; + } + } + + for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { + const MachineOperand &MO = MI.getOperand(i); + if (!MO.isRegister() || !MO.isDef()) + continue; + unsigned Reg = MO.getReg(); + RegKills.reset(Reg); + KillOps[Reg] = NULL; + } +} + + // ReusedOp - For each reused operand, we keep track of a bit of information, in // case we need to rollback upon processing a new operand. See comments below. namespace { @@ -479,8 +553,8 @@ namespace { // The MachineInstr operand that reused an available value. unsigned Operand; - // StackSlot - The spill slot of the value being reused. - unsigned StackSlot; + // StackSlotOrReMat - The spill slot or remat id of the value being reused. + unsigned StackSlotOrReMat; // PhysRegReused - The physical register the value was available in. unsigned PhysRegReused; @@ -493,8 +567,8 @@ namespace { ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr, unsigned vreg) - : Operand(o), StackSlot(ss), PhysRegReused(prr), AssignedPhysReg(apr), - VirtReg(vreg) {} + : Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr), + AssignedPhysReg(apr), VirtReg(vreg) {} }; /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that @@ -514,7 +588,7 @@ namespace { /// addReuse - If we choose to reuse a virtual register that is already /// available instead of reloading it, remember that we did so. - void addReuse(unsigned OpNo, unsigned StackSlot, + void addReuse(unsigned OpNo, unsigned StackSlotOrReMat, unsigned PhysRegReused, unsigned AssignedPhysReg, unsigned VirtReg) { // If the reload is to the assigned register anyway, no undo will be @@ -522,7 +596,7 @@ namespace { if (PhysRegReused == AssignedPhysReg) return; // Otherwise, remember this. - Reuses.push_back(ReusedOp(OpNo, StackSlot, PhysRegReused, + Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused, AssignedPhysReg, VirtReg)); } @@ -539,8 +613,11 @@ namespace { /// a new register to use, or evict the previous reload and use this reg. unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI, AvailableSpills &Spills, - std::map &MaybeDeadStores, - SmallSet &Rejected) { + std::vector &MaybeDeadStores, + SmallSet &Rejected, + BitVector &RegKills, + std::vector &KillOps, + VirtRegMap &VRM) { if (Reuses.empty()) return PhysReg; // This is most often empty. for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) { @@ -555,7 +632,8 @@ namespace { // Yup, use the reload register that we didn't use before. unsigned NewReg = Op.AssignedPhysReg; Rejected.insert(PhysReg); - return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected); + return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected, + RegKills, KillOps, VRM); } else { // Otherwise, we might also have a problem if a previously reused // value aliases the new register. If so, codegen the previous reload @@ -580,22 +658,30 @@ namespace { // register could hold a reuse. Check to see if it conflicts or // would prefer us to use a different register. unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg, - MI, Spills, MaybeDeadStores, Rejected); + MI, Spills, MaybeDeadStores, + Rejected, RegKills, KillOps, VRM); - MRI->loadRegFromStackSlot(*MBB, MI, NewPhysReg, - NewOp.StackSlot, AliasRC); + if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) { + MRI->reMaterialize(*MBB, MI, NewPhysReg, + VRM.getReMaterializedMI(NewOp.VirtReg)); + ++NumReMats; + } else { + MRI->loadRegFromStackSlot(*MBB, MI, NewPhysReg, + NewOp.StackSlotOrReMat, AliasRC); + // Any stores to this stack slot are not dead anymore. + MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL; + ++NumLoads; + } Spills.ClobberPhysReg(NewPhysReg); Spills.ClobberPhysReg(NewOp.PhysRegReused); - // Any stores to this stack slot are not dead anymore. - MaybeDeadStores.erase(NewOp.StackSlot); - MI->getOperand(NewOp.Operand).setReg(NewPhysReg); - Spills.addAvailable(NewOp.StackSlot, MI, NewPhysReg); - ++NumLoads; - DEBUG(MachineBasicBlock::iterator MII = MI; - DOUT << '\t' << *prior(MII)); + Spills.addAvailable(NewOp.StackSlotOrReMat, MI, NewPhysReg); + MachineBasicBlock::iterator MII = MI; + --MII; + UpdateKills(*MII, RegKills, KillOps); + DOUT << '\t' << *MII; DOUT << "Reuse undone!\n"; --NumReused; @@ -621,9 +707,13 @@ namespace { /// sees r1 is taken by t2, tries t2's reload register r0 ... unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI, AvailableSpills &Spills, - std::map &MaybeDeadStores) { + std::vector &MaybeDeadStores, + BitVector &RegKills, + std::vector &KillOps, + VirtRegMap &VRM) { SmallSet Rejected; - return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected); + return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected, + RegKills, KillOps, VRM); } }; } @@ -631,10 +721,11 @@ namespace { /// rewriteMBB - Keep track of which spills are available even after the /// register allocator is done with them. If possible, avoid reloading vregs. -void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, - std::vector &ReMatedMIs) { +void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) { DOUT << MBB.getBasicBlock()->getName() << ":\n"; + MachineFunction &MF = *MBB.getParent(); + // Spills - Keep track of which spilled values are available in physregs so // that we can choose to reuse the physregs instead of emitting reloads. AvailableSpills Spills(MRI, TII); @@ -645,13 +736,25 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // subsequently stored to, the original store is dead. This map keeps track // of inserted stores that are not used. If we see a subsequent store to the // same stack slot, the original store is deleted. - std::map MaybeDeadStores; + std::vector MaybeDeadStores; + MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL); + + // ReMatDefs - These are rematerializable def MIs which are not deleted. + SmallSet ReMatDefs; + + // Keep track of kill information. + BitVector RegKills(MRI->getNumRegs()); + std::vector KillOps; + KillOps.resize(MRI->getNumRegs(), NULL); - MachineFunction &MF = *MBB.getParent(); 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; + + bool Erased = false; + bool BackTracked = false; /// ReusedOperands - Keep track of operand reuse in case we need to undo /// reuse. @@ -660,31 +763,8 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // Loop over all of the implicit defs, clearing them from our available // sets. const TargetInstrDescriptor *TID = MI.getInstrDescriptor(); - - // If this instruction is being rematerialized, just remove it! - int FrameIdx; - if (TII->isTriviallyReMaterializable(&MI) || - TII->isLoadFromStackSlot(&MI, FrameIdx)) { - bool Remove = true; - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI.getOperand(i); - if (!MO.isRegister() || MO.getReg() == 0) - continue; // Ignore non-register operands. - if (MO.isDef() && !VRM.isReMaterialized(MO.getReg())) { - Remove = false; - break; - } - } - if (Remove) { - VRM.RemoveFromFoldedVirtMap(&MI); - ReMatedMIs.push_back(MI.removeFromParent()); - MII = NextMII; - continue; - } - } - - const unsigned *ImpDef = TID->ImplicitDefs; - if (ImpDef) { + if (TID->ImplicitDefs) { + const unsigned *ImpDef = TID->ImplicitDefs; for ( ; *ImpDef; ++ImpDef) { MF.setPhysRegUsed(*ImpDef); ReusedOperands.markClobbered(*ImpDef); @@ -698,25 +778,33 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, if (!MO.isRegister() || MO.getReg() == 0) continue; // Ignore non-register operands. - if (MRegisterInfo::isPhysicalRegister(MO.getReg())) { + unsigned VirtReg = MO.getReg(); + if (MRegisterInfo::isPhysicalRegister(VirtReg)) { // Ignore physregs for spilling, but remember that it is used by this // function. - MF.setPhysRegUsed(MO.getReg()); - ReusedOperands.markClobbered(MO.getReg()); + MF.setPhysRegUsed(VirtReg); + ReusedOperands.markClobbered(VirtReg); continue; } - assert(MRegisterInfo::isVirtualRegister(MO.getReg()) && + assert(MRegisterInfo::isVirtualRegister(VirtReg) && "Not a virtual or a physical register?"); - unsigned VirtReg = MO.getReg(); - if (!VRM.hasStackSlot(VirtReg)) { + unsigned SubIdx = 0; + bool isSubReg = RegMap->isSubRegister(VirtReg); + if (isSubReg) { + SubIdx = RegMap->getSubRegisterIndex(VirtReg); + VirtReg = RegMap->getSuperRegister(VirtReg); + } + + 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); - MI.getOperand(i).setReg(Phys); + unsigned RReg = isSubReg ? MRI->getSubReg(Phys, SubIdx) : Phys; + MI.getOperand(i).setReg(RReg); continue; } @@ -724,60 +812,70 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, if (!MO.isUse()) continue; // Handle defs in the loop below (handle use&def here though) - bool doReMat = VRM.isReMaterialized(VirtReg); - int StackSlot = VRM.getStackSlot(VirtReg); - unsigned PhysReg; + 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. - MachineInstr *SSMI = NULL; - if ((PhysReg = Spills.getSpillSlotPhysReg(StackSlot, SSMI))) { + 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 + // reuse the value. + ReuseSlot = VRM.getStackSlot(VirtReg); + if (ReuseSlot != VirtRegMap::NO_STACK_SLOT) + PhysReg = Spills.getSpillSlotOrReMatPhysReg(ReuseSlot); + } + + // 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 && + (isSubReg || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) { + const TargetRegisterClass* RC = RegMap->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; + int ti = TID->getOperandConstraint(i, TOI::TIED_TO); if (ti != -1 && - MI.getOperand(ti).isReg() && + MI.getOperand(ti).isRegister() && MI.getOperand(ti).getReg() == VirtReg) { // 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 = Spills.canClobberPhysReg(StackSlot) && + CanReuse = Spills.canClobberPhysReg(ReuseSlot) && !ReusedOperands.isClobbered(PhysReg); } if (CanReuse) { // If this stack slot value is already available, reuse it! - if (StackSlot > VirtRegMap::MAX_STACK_SLOT) - DOUT << "Reusing RM#" << StackSlot-VirtRegMap::MAX_STACK_SLOT-1; + if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT) + DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1; else - DOUT << "Reusing SS#" << StackSlot; + DOUT << "Reusing SS#" << ReuseSlot; DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg" << VirtReg <<" instead of reloading into physreg " << MRI->getName(VRM.getPhys(VirtReg)) << "\n"; - MI.getOperand(i).setReg(PhysReg); - - // Extend the live range of the MI that last kill the register if - // necessary. - bool WasKill = false; - if (SSMI) { - int UIdx = SSMI->findRegisterUseOperandIdx(PhysReg, true); - if (UIdx != -1) { - MachineOperand &MOK = SSMI->getOperand(UIdx); - WasKill = MOK.isKill(); - MOK.unsetIsKill(); - } - } - if (ti == -1) { - // Unless it's the use of a two-address code, transfer the kill - // of the reused register to this use. - if (WasKill) - MI.getOperand(i).setIsKill(); - Spills.addLastUse(PhysReg, &MI); - } + unsigned RReg = isSubReg ? MRI->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 @@ -793,14 +891,29 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // 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, StackSlot, PhysReg, + ReusedOperands.addReuse(i, ReuseSlot, PhysReg, VRM.getPhys(VirtReg), VirtReg); if (ti != -1) // 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) { + // This was the last use and the spilled value is still available + // for reuse. That means the spill was unnecessary! + MachineInstr* DeadStore = MaybeDeadStores[ReuseSlot]; + if (DeadStore) { + DOUT << "Removed dead store:\t" << *DeadStore; + InvalidateKills(*DeadStore, RegKills, KillOps); + MBB.erase(DeadStore); + VRM.RemoveFromFoldedVirtMap(DeadStore); + MaybeDeadStores[ReuseSlot] = NULL; + ++NumDSE; + } + } 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 @@ -821,65 +934,49 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // reuser. if (ReusedOperands.hasReuses()) DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI, - Spills, MaybeDeadStores); + 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 (StackSlot > VirtRegMap::MAX_STACK_SLOT) - DOUT << "Reusing RM#" << StackSlot-VirtRegMap::MAX_STACK_SLOT-1; + if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT) + DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1; else - DOUT << "Reusing SS#" << StackSlot; + DOUT << "Reusing SS#" << ReuseSlot; DOUT << " from physreg " << MRI->getName(PhysReg) << " for vreg" << VirtReg << " instead of reloading into same physreg.\n"; - MI.getOperand(i).setReg(PhysReg); + unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg; + MI.getOperand(i).setReg(RReg); ReusedOperands.markClobbered(PhysReg); ++NumReused; continue; } - const TargetRegisterClass* RC = MF.getSSARegMap()->getRegClass(VirtReg); + const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg); MF.setPhysRegUsed(DesignatedReg); ReusedOperands.markClobbered(DesignatedReg); - MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC); - - // Extend the live range of the MI that last kill the register if - // necessary. - bool WasKill = false; - if (SSMI) { - int UIdx = SSMI->findRegisterUseOperandIdx(PhysReg, true); - if (UIdx != -1) { - MachineOperand &MOK = SSMI->getOperand(UIdx); - WasKill = MOK.isKill(); - MOK.unsetIsKill(); - } - } + MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC); + MachineInstr *CopyMI = prior(MII); - if (WasKill) { - // Transfer kill to the next use. - int UIdx = CopyMI->findRegisterUseOperandIdx(PhysReg); - assert(UIdx != -1); - MachineOperand &MOU = CopyMI->getOperand(UIdx); - MOU.setIsKill(); - } - Spills.addLastUse(PhysReg, CopyMI); + UpdateKills(*CopyMI, RegKills, KillOps); // This invalidates DesignatedReg. Spills.ClobberPhysReg(DesignatedReg); - Spills.addAvailable(StackSlot, &MI, DesignatedReg); - MI.getOperand(i).setReg(DesignatedReg); + Spills.addAvailable(ReuseSlot, &MI, DesignatedReg); + unsigned RReg = + isSubReg ? MRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg; + MI.getOperand(i).setReg(RReg); DOUT << '\t' << *prior(MII); ++NumReused; continue; - } + } // is (PhysReg) // Otherwise, reload it and remember that we have it. PhysReg = VRM.getPhys(VirtReg); assert(PhysReg && "Must map virtreg to physreg!"); - const TargetRegisterClass* RC = MF.getSSARegMap()->getRegClass(VirtReg); // Note that, if we reused a register for a previous operand, the // register we want to reload into might not actually be @@ -887,29 +984,32 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // reuser. if (ReusedOperands.hasReuses()) PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI, - Spills, MaybeDeadStores); + Spills, MaybeDeadStores, RegKills, KillOps, VRM); MF.setPhysRegUsed(PhysReg); ReusedOperands.markClobbered(PhysReg); - if (doReMat) { + if (DoReMat) { MRI->reMaterialize(MBB, &MI, PhysReg, VRM.getReMaterializedMI(VirtReg)); ++NumReMats; } else { - MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC); + const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg); + MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC); ++NumLoads; } // This invalidates PhysReg. Spills.ClobberPhysReg(PhysReg); // Any stores to this stack slot are not dead anymore. - if (!doReMat) - MaybeDeadStores.erase(StackSlot); - Spills.addAvailable(StackSlot, &MI, PhysReg); + if (!DoReMat) + MaybeDeadStores[SSorRMId] = NULL; + Spills.addAvailable(SSorRMId, &MI, PhysReg); // Assumes this is the last use. IsKill will be unset if reg is reused // unless it's a two-address operand. if (TID->getOperandConstraint(i, TOI::TIED_TO) == -1) MI.getOperand(i).setIsKill(); - MI.getOperand(i).setReg(PhysReg); + unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg; + MI.getOperand(i).setReg(RReg); + UpdateKills(*prior(MII), RegKills, KillOps); DOUT << '\t' << *prior(MII); } @@ -918,99 +1018,71 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // 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 - VirtRegMap::MI2VirtMapTy::const_iterator I, End; + SmallSet 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; - if (!VRM.hasStackSlot(VirtReg)) { + if (VRM.isAssignedReg(VirtReg)) { DOUT << ": No stack slot!\n"; continue; } int SS = VRM.getStackSlot(VirtReg); + 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; - if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) { - if (FrameIdx == SS) { - // If this spill slot is available, turn it into a copy (or nothing) - // instead of leaving it as a load! - MachineInstr *SSMI = NULL; - if (unsigned InReg = Spills.getSpillSlotPhysReg(SS, SSMI)) { - DOUT << "Promoted Load To Copy: " << MI; - if (DestReg != InReg) { - MRI->copyRegToReg(MBB, &MI, DestReg, InReg, - MF.getSSARegMap()->getRegClass(VirtReg)); - // 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. - } else - DOUT << "Removing now-noop copy: " << MI; - - // Either way, the live range of the last kill of InReg has been - // extended. Remove its kill. - bool WasKill = false; - if (SSMI) { - int UIdx = SSMI->findRegisterUseOperandIdx(InReg, true); - if (UIdx != -1) { - MachineOperand &MOK = SSMI->getOperand(UIdx); - WasKill = MOK.isKill(); - MOK.unsetIsKill(); - } - } - if (NextMII != MBB.end()) { - // If NextMII uses InReg and the use is not a two address - // operand, mark it killed. - int UIdx = NextMII->findRegisterUseOperandIdx(InReg); - if (UIdx != -1) { - MachineOperand &MOU = NextMII->getOperand(UIdx); - if (WasKill) { - const TargetInstrDescriptor *NTID = - NextMII->getInstrDescriptor(); - if (UIdx >= NTID->numOperands || - NTID->getOperandConstraint(UIdx, TOI::TIED_TO) == -1) - MOU.setIsKill(); - } - Spills.addLastUse(InReg, &(*NextMII)); - } - } + 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 = RegMap->getRegClass(VirtReg); + MRI->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC); + // 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. + BackTracked = true; + } else + DOUT << "Removing now-noop copy: " << MI; - VRM.RemoveFromFoldedVirtMap(&MI); - MBB.erase(&MI); - goto ProcessNextInst; - } + VRM.RemoveFromFoldedVirtMap(&MI); + MBB.erase(&MI); + Erased = 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. - std::map::iterator MDSI = MaybeDeadStores.find(SS); - if (MDSI != MaybeDeadStores.end()) { - if (MR & VirtRegMap::isRef) // Previous store is not dead. - MaybeDeadStores.erase(MDSI); - else { + MachineInstr* DeadStore = MaybeDeadStores[SS]; + if (DeadStore) { + if (!(MR & VirtRegMap::isRef)) { // Previous store is dead. // If we get here, the store is dead, nuke it now. assert(VirtRegMap::isMod && "Can't be modref!"); - DOUT << "Removed dead store:\t" << *MDSI->second; - MBB.erase(MDSI->second); - VRM.RemoveFromFoldedVirtMap(MDSI->second); - MaybeDeadStores.erase(MDSI); + DOUT << "Removed dead store:\t" << *DeadStore; + InvalidateKills(*DeadStore, RegKills, KillOps); + MBB.erase(DeadStore); + VRM.RemoveFromFoldedVirtMap(DeadStore); ++NumDSE; } + MaybeDeadStores[SS] = NULL; } // 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.ModifyStackSlot(SS); + 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 @@ -1048,8 +1120,8 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) { ++NumDCE; DOUT << "Removing now-noop copy: " << MI; - Spills.removeLastUse(Src, &MI); MBB.erase(&MI); + Erased = true; VRM.RemoveFromFoldedVirtMap(&MI); Spills.disallowClobberPhysReg(VirtReg); goto ProcessNextInst; @@ -1064,18 +1136,24 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, 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); + 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 = MF.getSSARegMap()->getRegClass(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. @@ -1089,56 +1167,85 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM, // 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); + Spills, MaybeDeadStores, RegKills, KillOps, VRM); } } MF.setPhysRegUsed(PhysReg); ReusedOperands.markClobbered(PhysReg); - MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC); - DOUT << "Store:\t" << *next(MII); 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 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 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; - MBB.erase(LastStore); - VRM.RemoveFromFoldedVirtMap(LastStore); - } - 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.ModifyStackSlot(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; - Spills.removeLastUse(Src, &MI); - MBB.erase(&MI); - VRM.RemoveFromFoldedVirtMap(&MI); - goto ProcessNextInst; + // 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) + for (MachineBasicBlock::iterator II = MI; II != NextMII; ++II) + UpdateKills(*II, RegKills, KillOps); MII = NextMII; } } - llvm::Spiller* llvm::createSpiller() { switch (SpillerOpt) { default: assert(0 && "Unreachable!");