#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
#include <algorithm>
-#include <iostream>
using namespace llvm;
-namespace {
- Statistic<> NumSpills("spiller", "Number of register spills");
- Statistic<> NumStores("spiller", "Number of stores added");
- Statistic<> NumLoads ("spiller", "Number of loads added");
- Statistic<> NumReused("spiller", "Number of values reused");
- Statistic<> NumDSE ("spiller", "Number of dead stores elided");
+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");
+STATISTIC(NumDSE , "Number of dead stores elided");
+STATISTIC(NumDCE , "Number of copies elided");
+namespace {
enum SpillerName { simple, local };
- cl::opt<SpillerName>
+ static cl::opt<SpillerName>
SpillerOpt("spiller",
cl::desc("Spiller to use: (default: local)"),
cl::Prefix,
// VirtRegMap implementation
//===----------------------------------------------------------------------===//
+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) {
assert(MRegisterInfo::isVirtualRegister(virtReg));
assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
"attempt to assign stack slot to already spilled register");
+ assert((frameIndex >= 0 ||
+ (frameIndex >= MF.getFrameInfo()->getObjectIndexBegin())) &&
+ "illegal fixed frame index");
Virt2StackSlotMap[virtReg] = frameIndex;
}
+int VirtRegMap::assignVirtReMatId(unsigned virtReg) {
+ assert(MRegisterInfo::isVirtualRegister(virtReg));
+ assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT &&
+ "attempt to assign re-mat id to already spilled register");
+ 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.
}
ModRef MRInfo;
- if (!OldMI->getOperand(OpNo).isDef()) {
- assert(OldMI->getOperand(OpNo).isUse() && "Operand is not use or def?");
- MRInfo = isRef;
+ const TargetInstrDescriptor *TID = OldMI->getInstrDescriptor();
+ if (TID->getOperandConstraint(OpNo, TOI::TIED_TO) != -1 ||
+ TID->findTiedToSrcOperand(OpNo) != -1) {
+ // Folded a two-address operand.
+ MRInfo = isModRef;
+ } else if (OldMI->getOperand(OpNo).isDef()) {
+ MRInfo = isMod;
} else {
- MRInfo = OldMI->getOperand(OpNo).isUse() ? isModRef : isMod;
+ MRInfo = isRef;
}
// add new memory reference
MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo)));
}
+void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *MI, ModRef MRInfo) {
+ MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(MI);
+ MI2VirtMap.insert(IP, std::make_pair(MI, std::make_pair(VirtReg, MRInfo)));
+}
+
void VirtRegMap::print(std::ostream &OS) const {
const MRegisterInfo* MRI = MF.getTarget().getRegisterInfo();
OS << '\n';
}
-void VirtRegMap::dump() const { print(std::cerr); }
+void VirtRegMap::dump() const {
+ print(DOUT);
+}
//===----------------------------------------------------------------------===//
Spiller::~Spiller() {}
namespace {
- struct SimpleSpiller : public Spiller {
- bool runOnMachineFunction(MachineFunction& mf, const VirtRegMap &VRM);
+ struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
+ bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
};
}
-bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF,
- const VirtRegMap &VRM) {
- DEBUG(std::cerr << "********** REWRITE MACHINE CODE **********\n");
- DEBUG(std::cerr << "********** Function: "
- << MF.getFunction()->getName() << '\n');
+bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
+ DOUT << "********** REWRITE MACHINE CODE **********\n";
+ DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
const TargetMachine &TM = MF.getTarget();
const MRegisterInfo &MRI = *TM.getRegisterInfo();
- bool *PhysRegsUsed = MF.getUsedPhysregs();
// LoadedRegs - Keep track of which vregs are loaded, so that we only load
// each vreg once (in the case where a spilled vreg is used by multiple
for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
MBBI != E; ++MBBI) {
- DEBUG(std::cerr << MBBI->getBasicBlock()->getName() << ":\n");
+ DOUT << MBBI->getBasicBlock()->getName() << ":\n";
MachineBasicBlock &MBB = *MBBI;
for (MachineBasicBlock::iterator MII = MBB.begin(),
E = MBB.end(); MII != E; ++MII) {
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);
MRI.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
LoadedRegs.push_back(VirtReg);
++NumLoads;
- DEBUG(std::cerr << '\t' << *prior(MII));
+ DOUT << '\t' << *prior(MII);
}
if (MO.isDef()) {
++NumStores;
}
}
- PhysRegsUsed[PhysReg] = true;
- MI.SetMachineOperandReg(i, PhysReg);
+ MF.setPhysRegUsed(PhysReg);
+ MI.getOperand(i).setReg(PhysReg);
} else {
- PhysRegsUsed[MO.getReg()] = true;
+ MF.setPhysRegUsed(MO.getReg());
}
}
- DEBUG(std::cerr << '\t' << MI);
+ DOUT << '\t' << MI;
LoadedRegs.clear();
}
}
//===----------------------------------------------------------------------===//
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
/// register pressure in other blocks).
- class LocalSpiller : public Spiller {
+ class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
+ SSARegMap *RegMap;
const MRegisterInfo *MRI;
const TargetInstrInfo *TII;
public:
- bool runOnMachineFunction(MachineFunction &MF, const VirtRegMap &VRM) {
+ bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
+ RegMap = MF.getSSARegMap();
MRI = MF.getTarget().getRegisterInfo();
TII = MF.getTarget().getInstrInfo();
- DEBUG(std::cerr << "\n**** Local spiller rewriting function '"
- << MF.getFunction()->getName() << "':\n");
+ DOUT << "\n**** Local spiller rewriting function '"
+ << MF.getFunction()->getName() << "':\n";
+ DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!) ****\n";
+ DEBUG(MF.dump());
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
MBB != E; ++MBB)
RewriteMBB(*MBB, VRM);
+
+ DOUT << "**** Post Machine Instrs ****\n";
+ DEBUG(MF.dump());
+
return true;
}
private:
- void RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM);
- void ClobberPhysReg(unsigned PR, std::map<int, unsigned> &SpillSlots,
- std::map<unsigned, int> &PhysRegs);
- void ClobberPhysRegOnly(unsigned PR, std::map<int, unsigned> &SpillSlots,
- std::map<unsigned, int> &PhysRegs);
+ 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 LocalSpiller::ClobberPhysRegOnly(unsigned PhysReg,
- std::map<int, unsigned> &SpillSlots,
- std::map<unsigned, int> &PhysRegs) {
- std::map<unsigned, int>::iterator I = PhysRegs.find(PhysReg);
- if (I != PhysRegs.end()) {
- int Slot = I->second;
- PhysRegs.erase(I);
- assert(SpillSlots[Slot] == PhysReg && "Bidirectional map mismatch!");
- SpillSlots.erase(Slot);
- DEBUG(std::cerr << "PhysReg " << MRI->getName(PhysReg)
- << " clobbered, invalidating SS#" << Slot << "\n");
+/// AvailableSpills - As the local spiller is scanning and rewriting an MBB from
+/// 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 / 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;
+
+ // 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<int, unsigned> SpillSlotsOrReMatsAvailable;
+
+ // 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<unsigned, int> PhysRegsAvailable;
+
+ void disallowClobberPhysRegOnly(unsigned PhysReg);
+
+ void ClobberPhysRegOnly(unsigned PhysReg);
+public:
+ AvailableSpills(const MRegisterInfo *mri, const TargetInstrInfo *tii)
+ : MRI(mri), TII(tii) {
+ }
+
+ const MRegisterInfo *getRegInfo() const { return MRI; }
+
+ /// 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<int, unsigned>::const_iterator I =
+ SpillSlotsOrReMatsAvailable.find(Slot);
+ if (I != SpillSlotsOrReMatsAvailable.end()) {
+ return I->second >> 1; // Remove the CanClobber bit.
+ }
+ return 0;
+ }
+
+ /// 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.
+ ModifyStackSlotOrReMat(SlotOrReMat);
+
+ PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
+ SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber;
+
+ if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
+ DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
+ else
+ 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 SlotOrReMat) const {
+ assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
+ "Value not available!");
+ return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
+ }
+
+ /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
+ /// stackslot register. The register is still available but is no longer
+ /// allowed to be modifed.
+ void disallowClobberPhysReg(unsigned PhysReg);
+
+ /// ClobberPhysReg - This is called when the specified physreg changes
+ /// value. We use this to invalidate any info about stuff that lives in
+ /// it and any of its aliases.
+ void ClobberPhysReg(unsigned PhysReg);
+
+ /// 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);
+};
+}
+
+/// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
+/// stackslot register. The register is still available but is no longer
+/// allowed to be modifed.
+void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
+ std::multimap<unsigned, int>::iterator I =
+ PhysRegsAvailable.lower_bound(PhysReg);
+ while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
+ int SlotOrReMat = I->second;
+ I++;
+ assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
+ "Bidirectional map mismatch!");
+ SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1;
+ DOUT << "PhysReg " << MRI->getName(PhysReg)
+ << " copied, it is available for use but can no longer be modified\n";
+ }
+}
+
+/// disallowClobberPhysReg - Unset the CanClobber bit of the specified
+/// stackslot register and its aliases. The register and its aliases may
+/// still available but is no longer allowed to be modifed.
+void AvailableSpills::disallowClobberPhysReg(unsigned PhysReg) {
+ for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
+ disallowClobberPhysRegOnly(*AS);
+ disallowClobberPhysRegOnly(PhysReg);
+}
+/// ClobberPhysRegOnly - This is called when the specified physreg changes
+/// value. We use this to invalidate any info about stuff we thing lives in it.
+void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
+ std::multimap<unsigned, int>::iterator I =
+ PhysRegsAvailable.lower_bound(PhysReg);
+ while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
+ int SlotOrReMat = I->second;
+ PhysRegsAvailable.erase(I++);
+ assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
+ "Bidirectional map mismatch!");
+ SpillSlotsOrReMatsAvailable.erase(SlotOrReMat);
+ DOUT << "PhysReg " << MRI->getName(PhysReg)
+ << " clobbered, invalidating ";
+ if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
+ DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
+ else
+ DOUT << "SS#" << SlotOrReMat << "\n";
}
}
-void LocalSpiller::ClobberPhysReg(unsigned PhysReg,
- std::map<int, unsigned> &SpillSlots,
- std::map<unsigned, int> &PhysRegs) {
+/// ClobberPhysReg - This is called when the specified physreg changes
+/// value. We use this to invalidate any info about stuff we thing lives in
+/// it and any of its aliases.
+void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
- ClobberPhysRegOnly(*AS, SpillSlots, PhysRegs);
- ClobberPhysRegOnly(PhysReg, SpillSlots, PhysRegs);
+ ClobberPhysRegOnly(*AS);
+ ClobberPhysRegOnly(PhysReg);
+}
+
+/// 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<int, unsigned>::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.
+ std::multimap<unsigned, int>::iterator I = PhysRegsAvailable.lower_bound(Reg);
+ for (; ; ++I) {
+ assert(I != PhysRegsAvailable.end() && I->first == Reg &&
+ "Map inverse broken!");
+ 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<MachineOperand*> &KillOps,
+ 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())
+ 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<MachineOperand*> &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;
+ }
}
// 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;
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
+ /// is reused instead of reloaded.
+ class VISIBILITY_HIDDEN ReuseInfo {
+ MachineInstr &MI;
+ std::vector<ReusedOp> Reuses;
+ BitVector PhysRegsClobbered;
+ public:
+ ReuseInfo(MachineInstr &mi, const MRegisterInfo *mri) : MI(mi) {
+ PhysRegsClobbered.resize(mri->getNumRegs());
+ }
+
+ bool hasReuses() const {
+ return !Reuses.empty();
+ }
+
+ /// 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 StackSlotOrReMat,
+ unsigned PhysRegReused, unsigned AssignedPhysReg,
+ unsigned VirtReg) {
+ // If the reload is to the assigned register anyway, no undo will be
+ // required.
+ if (PhysRegReused == AssignedPhysReg) return;
+
+ // Otherwise, remember this.
+ Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused,
+ AssignedPhysReg, VirtReg));
+ }
+ void markClobbered(unsigned PhysReg) {
+ PhysRegsClobbered.set(PhysReg);
+ }
-/// 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, const VirtRegMap &VRM) {
+ bool isClobbered(unsigned PhysReg) const {
+ return PhysRegsClobbered.test(PhysReg);
+ }
+
+ /// GetRegForReload - We are about to emit a reload into PhysReg. If there
+ /// is some other operand that is using the specified register, either pick
+ /// a new register to use, or evict the previous reload and use this reg.
+ unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
+ AvailableSpills &Spills,
+ std::vector<MachineInstr*> &MaybeDeadStores,
+ SmallSet<unsigned, 8> &Rejected,
+ BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ VirtRegMap &VRM) {
+ if (Reuses.empty()) return PhysReg; // This is most often empty.
+
+ for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
+ ReusedOp &Op = Reuses[ro];
+ // If we find some other reuse that was supposed to use this register
+ // exactly for its reload, we can change this reload to use ITS reload
+ // register. That is, unless its reload register has already been
+ // considered and subsequently rejected because it has also been reused
+ // by another operand.
+ if (Op.PhysRegReused == PhysReg &&
+ Rejected.count(Op.AssignedPhysReg) == 0) {
+ // 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,
+ 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
+ // and use this one.
+ unsigned PRRU = Op.PhysRegReused;
+ const MRegisterInfo *MRI = Spills.getRegInfo();
+ if (MRI->areAliases(PRRU, PhysReg)) {
+ // Okay, we found out that an alias of a reused register
+ // was used. This isn't good because it means we have
+ // to undo a previous reuse.
+ MachineBasicBlock *MBB = MI->getParent();
+ const TargetRegisterClass *AliasRC =
+ MBB->getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
+
+ // Copy Op out of the vector and remove it, we're going to insert an
+ // explicit load for it.
+ ReusedOp NewOp = Op;
+ Reuses.erase(Reuses.begin()+ro);
+
+ // Ok, we're going to try to reload the assigned physreg into the
+ // slot that we were supposed to in the first place. However, that
+ // 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, RegKills, KillOps, VRM);
+
+ 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);
+
+ MI->getOperand(NewOp.Operand).setReg(NewPhysReg);
+
+ Spills.addAvailable(NewOp.StackSlotOrReMat, MI, NewPhysReg);
+ MachineBasicBlock::iterator MII = MI;
+ --MII;
+ UpdateKills(*MII, RegKills, KillOps);
+ DOUT << '\t' << *MII;
+
+ DOUT << "Reuse undone!\n";
+ --NumReused;
+
+ // Finally, PhysReg is now available, go ahead and use it.
+ return PhysReg;
+ }
+ }
+ }
+ return PhysReg;
+ }
- // SpillSlotsAvailable - This map keeps track of all of the spilled virtual
- // register values that are still available, due to being loaded to stored to,
- // but not invalidated yet.
- std::map<int, unsigned> SpillSlotsAvailable;
+ /// GetRegForReload - Helper for the above GetRegForReload(). Add a
+ /// 'Rejected' set to remember which registers have been considered and
+ /// rejected for the reload. This avoids infinite looping in case like
+ /// this:
+ /// t1 := op t2, t3
+ /// t2 <- assigned r0 for use by the reload but ended up reuse r1
+ /// t3 <- assigned r1 for use by the reload but ended up reuse r0
+ /// t1 <- desires r1
+ /// sees r1 is taken by t2, tries t2's reload register r0
+ /// sees r0 is taken by t3, tries t3's reload register r1
+ /// sees r1 is taken by t2, tries t2's reload register r0 ...
+ unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
+ AvailableSpills &Spills,
+ std::vector<MachineInstr*> &MaybeDeadStores,
+ BitVector &RegKills,
+ std::vector<MachineOperand*> &KillOps,
+ VirtRegMap &VRM) {
+ SmallSet<unsigned, 8> Rejected;
+ return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected,
+ RegKills, KillOps, VRM);
+ }
+ };
+}
- // PhysRegsAvailable - This is the inverse of SpillSlotsAvailable, indicating
- // which physregs are in use holding a stack slot value.
- std::map<unsigned, int> PhysRegsAvailable;
+/// 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);
+ }
+ }
- DEBUG(std::cerr << MBB.getBasicBlock()->getName() << ":\n");
+ 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) ||
+ RegMap->isSubRegister(VirtReg))
+ 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;
+}
- std::vector<ReusedOp> ReusedOperands;
+/// 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) {
+ DOUT << MBB.getBasicBlock()->getName() << ":\n";
- // DefAndUseVReg - When we see a def&use operand that is spilled, keep track
- // of it. ".first" is the machine operand index (should always be 0 for now),
- // and ".second" is the virtual register that is spilled.
- std::vector<std::pair<unsigned, unsigned> > DefAndUseVReg;
+ 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);
+
// MaybeDeadStores - When we need to write a value back into a stack slot,
// keep track of the inserted store. If the stack slot value is never read
// (because the value was used from some available register, for example), and
// 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<int, MachineInstr*> MaybeDeadStores;
+ std::vector<MachineInstr*> MaybeDeadStores;
+ MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL);
+
+ // ReMatDefs - These are rematerializable def MIs which are not deleted.
+ SmallSet<MachineInstr*, 4> ReMatDefs;
- bool *PhysRegsUsed = MBB.getParent()->getUsedPhysregs();
+ // Keep track of kill information.
+ BitVector RegKills(MRI->getNumRegs());
+ std::vector<MachineOperand*> KillOps;
+ KillOps.resize(MRI->getNumRegs(), NULL);
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
MII != E; ) {
- MachineInstr &MI = *MII;
MachineBasicBlock::iterator NextMII = MII; ++NextMII;
- ReusedOperands.clear();
- DefAndUseVReg.clear();
+ 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);
+
+ const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
// Process all of the spilled uses and all non spilled reg references.
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
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.
- PhysRegsUsed[MO.getReg()] = true;
+ MF.setPhysRegUsed(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);
- PhysRegsUsed[Phys] = true;
- MI.SetMachineOperandReg(i, Phys);
+ MF.setPhysRegUsed(Phys);
+ if (MO.isDef())
+ ReusedOperands.markClobbered(Phys);
+ unsigned RReg = isSubReg ? MRI->getSubReg(Phys, SubIdx) : Phys;
+ MI.getOperand(i).setReg(RReg);
continue;
}
if (!MO.isUse())
continue; // Handle defs in the loop below (handle use&def here though)
- // If this is both a def and a use, we need to emit a store to the
- // stack slot after the instruction. Keep track of D&U operands
- // because we are about to change it to a physreg here.
- if (MO.isDef()) {
- // Remember that this was a def-and-use operand, and that the
- // stack slot is live after this instruction executes.
- DefAndUseVReg.push_back(std::make_pair(i, 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.
- std::map<int, unsigned>::iterator SSI =
- SpillSlotsAvailable.find(StackSlot);
- if (SSI != SpillSlotsAvailable.end()) {
- DEBUG(std::cerr << "Reusing SS#" << StackSlot << " from physreg "
- << MRI->getName(SSI->second) << " for vreg"
- << VirtReg <<" instead of reloading into physreg "
- << MRI->getName(VRM.getPhys(VirtReg)) << "\n");
- // If this stack slot value is already available, reuse it!
- PhysReg = SSI->second;
- MI.SetMachineOperandReg(i, PhysReg);
-
- // 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.
+ unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
+ if (!PhysReg && DoReMat) {
+ // This use is rematerializable. But perhaps the value is available in
+ // 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)
+ 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).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(ReuseSlot) &&
+ !ReusedOperands.isClobbered(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 "
+ << 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;
+ 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 (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);
+ VRM.RemoveFromFoldedVirtMap(DeadStore);
+ MBB.erase(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
+ // 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 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.push_back(ReusedOp(i, StackSlot, PhysReg,
- VRM.getPhys(VirtReg), VirtReg));
+ // 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 " << MRI->getName(PhysReg) << " for vreg"
+ << VirtReg
+ << " instead of reloading into same physreg.\n";
+ unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
+ MI.getOperand(i).setReg(RReg);
+ ReusedOperands.markClobbered(PhysReg);
+ ++NumReused;
+ continue;
+ }
+
+ const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
+ MF.setPhysRegUsed(DesignatedReg);
+ ReusedOperands.markClobbered(DesignatedReg);
+ MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
+
+ MachineInstr *CopyMI = prior(MII);
+ UpdateKills(*CopyMI, RegKills, KillOps);
+
+ // This invalidates DesignatedReg.
+ Spills.ClobberPhysReg(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;
- }
+ } // if (PhysReg)
// Otherwise, reload it and remember that we have it.
PhysReg = VRM.getPhys(VirtReg);
assert(PhysReg && "Must map virtreg to physreg!");
- const TargetRegisterClass* RC =
- MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
- RecheckRegister:
// 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.empty()) // This is most often empty.
- for (unsigned ro = 0, e = ReusedOperands.size(); ro != e; ++ro)
- if (ReusedOperands[ro].PhysRegReused == PhysReg) {
- // Yup, use the reload register that we didn't use before.
- PhysReg = ReusedOperands[ro].AssignedPhysReg;
- goto RecheckRegister;
- } else {
- ReusedOp &Op = ReusedOperands[ro];
- unsigned PRRU = Op.PhysRegReused;
- if (MRI->areAliases(PRRU, PhysReg)) {
- // Okay, we found out that an alias of a reused register
- // was used. This isn't good because it means we have
- // to undo a previous reuse.
- const TargetRegisterClass *AliasRC =
- MBB.getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
- MRI->loadRegFromStackSlot(MBB, &MI, Op.AssignedPhysReg,
- Op.StackSlot, AliasRC);
- ClobberPhysReg(Op.AssignedPhysReg, SpillSlotsAvailable,
- PhysRegsAvailable);
-
- // Any stores to this stack slot are not dead anymore.
- MaybeDeadStores.erase(Op.StackSlot);
-
- MI.SetMachineOperandReg(Op.Operand, Op.AssignedPhysReg);
- PhysRegsAvailable[Op.AssignedPhysReg] = Op.StackSlot;
- SpillSlotsAvailable[Op.StackSlot] = Op.AssignedPhysReg;
- PhysRegsAvailable.erase(Op.PhysRegReused);
- DEBUG(std::cerr << "Remembering SS#" << Op.StackSlot
- << " in physreg "
- << MRI->getName(Op.AssignedPhysReg) << "\n");
- ++NumLoads;
- DEBUG(std::cerr << '\t' << *prior(MII));
-
- DEBUG(std::cerr << "Reuse undone!\n");
- ReusedOperands.erase(ReusedOperands.begin()+ro);
- --NumReused;
- goto ContinueReload;
- }
- }
- ContinueReload:
- PhysRegsUsed[PhysReg] = true;
- MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
+ if (ReusedOperands.hasReuses())
+ PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
+ Spills, MaybeDeadStores, RegKills, KillOps, VRM);
+
+ MF.setPhysRegUsed(PhysReg);
+ ReusedOperands.markClobbered(PhysReg);
+ if (DoReMat) {
+ MRI->reMaterialize(MBB, &MI, PhysReg, VRM.getReMaterializedMI(VirtReg));
+ ++NumReMats;
+ } else {
+ const TargetRegisterClass* RC = RegMap->getRegClass(VirtReg);
+ MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
+ ++NumLoads;
+ }
// This invalidates PhysReg.
- ClobberPhysReg(PhysReg, SpillSlotsAvailable, PhysRegsAvailable);
+ Spills.ClobberPhysReg(PhysReg);
// Any stores to this stack slot are not dead anymore.
- MaybeDeadStores.erase(StackSlot);
-
- MI.SetMachineOperandReg(i, PhysReg);
- PhysRegsAvailable[PhysReg] = StackSlot;
- SpillSlotsAvailable[StackSlot] = PhysReg;
- DEBUG(std::cerr << "Remembering SS#" << StackSlot <<" in physreg "
- << MRI->getName(PhysReg) << "\n");
- ++NumLoads;
- DEBUG(std::cerr << '\t' << *prior(MII));
+ 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();
+ unsigned RReg = isSubReg ? MRI->getSubReg(PhysReg, SubIdx) : PhysReg;
+ MI.getOperand(i).setReg(RReg);
+ UpdateKills(*prior(MII), RegKills, KillOps);
+ DOUT << '\t' << *prior(MII);
}
- // Loop over all of the implicit defs, clearing them from our available
- // sets.
- for (const unsigned *ImpDef = TII->getImplicitDefs(MI.getOpcode());
- *ImpDef; ++ImpDef) {
- PhysRegsUsed[*ImpDef] = true;
- ClobberPhysReg(*ImpDef, SpillSlotsAvailable, PhysRegsAvailable);
- }
-
- DEBUG(std::cerr << '\t' << MI);
+ 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
- VirtRegMap::MI2VirtMapTy::const_iterator I, End;
+ SmallSet<int, 2> FoldedSS;
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
- DEBUG(std::cerr << "Folded vreg: " << I->second.first << " MR: "
- << I->second.second);
unsigned VirtReg = I->second.first;
VirtRegMap::ModRef MR = I->second.second;
- if (!VRM.hasStackSlot(VirtReg)) {
- DEBUG(std::cerr << ": No stack slot!\n");
+ DOUT << "Folded vreg: " << VirtReg << " MR: " << MR;
+ if (VRM.isAssignedReg(VirtReg)) {
+ DOUT << ": No stack slot!\n";
continue;
}
int SS = VRM.getStackSlot(VirtReg);
- DEBUG(std::cerr << " - StackSlot: " << SS << "\n");
+ 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)) {
+ 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!
- std::map<int, unsigned>::iterator It = SpillSlotsAvailable.find(SS);
- if (FrameIdx == SS && It != SpillSlotsAvailable.end()) {
- DEBUG(std::cerr << "Promoted Load To Copy: " << MI);
- MachineFunction &MF = *MBB.getParent();
- if (DestReg != It->second) {
- MRI->copyRegToReg(MBB, &MI, DestReg, It->second,
- MF.getSSARegMap()->getRegClass(VirtReg));
+ 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);
+ Erased = true;
+ goto ProcessNextInst;
+ }
+ } else {
+ unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
+ SmallVector<MachineInstr*, 4> NewMIs;
+ if (PhysReg &&
+ MRI->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
+ MBB.insert(MII, NewMIs[0]);
+ VRM.RemoveFromFoldedVirtMap(&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.
- std::map<int, MachineInstr*>::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) {
+ bool isDead = !(MR & VirtRegMap::isRef);
+ MachineInstr *NewStore = NULL;
+ if (MR & VirtRegMap::isModRef) {
+ unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
+ SmallVector<MachineInstr*, 4> NewMIs;
+ if (PhysReg &&
+ DeadStore->findRegisterUseOperandIdx(PhysReg, true) != -1 &&
+ MRI->unfoldMemoryOperand(MF, &MI, PhysReg, false, true, NewMIs)) {
+ MBB.insert(MII, NewMIs[0]);
+ NewStore = NewMIs[1];
+ MBB.insert(MII, NewStore);
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ MBB.erase(&MI);
+ Erased = true;
+ --NextMII;
+ --NextMII; // backtrack to the unfolded instruction.
+ BackTracked = true;
+ isDead = true;
+ }
+ }
+
+ if (isDead) { // Previous store is dead.
// If we get here, the store is dead, nuke it now.
- assert(MR == VirtRegMap::isMod && "Can't be modref!");
- MBB.erase(MDSI->second);
- MaybeDeadStores.erase(MDSI);
- ++NumDSE;
+ DOUT << "Removed dead store:\t" << *DeadStore;
+ InvalidateKills(*DeadStore, RegKills, KillOps);
+ VRM.RemoveFromFoldedVirtMap(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) {
- std::map<int, unsigned>::iterator It = SpillSlotsAvailable.find(SS);
- if (It != SpillSlotsAvailable.end()) {
- PhysRegsAvailable.erase(It->second);
- SpillSlotsAvailable.erase(It);
+ // 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(MRegisterInfo::isPhysicalRegister(SrcReg) &&
+ "Src hasn't been allocated yet?");
+ // 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, &MI, SrcReg, false/*don't clobber*/);
+ }
}
}
}
// 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();
-
- bool TakenCareOf = false;
- if (!MRegisterInfo::isVirtualRegister(VirtReg)) {
- // Check to see if this is a def-and-use vreg operand that we do need
- // to insert a store for.
- bool OpTakenCareOf = false;
- if (MO.isUse() && !DefAndUseVReg.empty()) {
- for (unsigned dau = 0, e = DefAndUseVReg.size(); dau != e; ++dau)
- if (DefAndUseVReg[dau].first == i) {
- VirtReg = DefAndUseVReg[dau].second;
- OpTakenCareOf = true;
- break;
- }
- }
+ if (!(MO.isRegister() && MO.getReg() && MO.isDef()))
+ continue;
- if (!OpTakenCareOf) {
- ClobberPhysReg(VirtReg, SpillSlotsAvailable, PhysRegsAvailable);
- TakenCareOf = true;
- }
+ 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);
+
+ // 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 (!TakenCareOf) {
- // The only vregs left are stack slot definitions.
- int StackSlot = VRM.getStackSlot(VirtReg);
- const TargetRegisterClass *RC =
- MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
- unsigned PhysReg;
-
- // If this is a def&use operand, and we used a different physreg for
- // it than the one assigned, make sure to execute the store from the
- // correct physical register.
- if (MO.getReg() == VirtReg)
- PhysReg = VRM.getPhys(VirtReg);
- else
- PhysReg = MO.getReg();
-
- PhysRegsUsed[PhysReg] = true;
- MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
- DEBUG(std::cerr << "Store:\t" << *next(MII));
- MI.SetMachineOperandReg(i, PhysReg);
+ // 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;
+ }
- // If there is a dead store to this stack slot, nuke it now.
- MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
- if (LastStore) {
- DEBUG(std::cerr << " Killed store:\t" << *LastStore);
- ++NumDSE;
- MBB.erase(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.
- std::map<int, unsigned>::iterator SSA =
- SpillSlotsAvailable.find(StackSlot);
- if (SSA != SpillSlotsAvailable.end()) {
- // Remove the record for physreg.
- PhysRegsAvailable.erase(SSA->second);
- SpillSlotsAvailable.erase(SSA);
- }
- ClobberPhysReg(PhysReg, SpillSlotsAvailable, PhysRegsAvailable);
+ bool DoReMat = VRM.isReMaterialized(VirtReg);
+ if (DoReMat)
+ ReMatDefs.insert(&MI);
- PhysRegsAvailable[PhysReg] = StackSlot;
- SpillSlotsAvailable[StackSlot] = PhysReg;
- DEBUG(std::cerr << "Updating SS#" << StackSlot <<" in physreg "
- << MRI->getName(PhysReg) << " for virtreg #"
- << VirtReg << "\n");
+ // The only vregs left are stack slot definitions.
+ int StackSlot = VRM.getStackSlot(VirtReg);
+ const TargetRegisterClass *RC = RegMap->getRegClass(VirtReg);
- ++NumStores;
- VirtReg = PhysReg;
+ // 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,
+ 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, 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;
+ }
+ }
+ }
}
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!");
projects / oota-llvm.git / blobdiff