#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<> NumDCE ("spiller", "Number of copies elided");
+STATISTIC(NumSpills, "Number of register spills");
+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) {
+ grow();
+}
+
void VirtRegMap::grow() {
Virt2PhysMap.grow(MF.getSSARegMap()->getLastVirtReg());
Virt2StackSlotMap.grow(MF.getSSARegMap()->getLastVirtReg());
}
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
OS << '\n';
}
-void VirtRegMap::dump() const { print(std::cerr); }
+void VirtRegMap::dump() const {
+ print(DOUT);
+}
//===----------------------------------------------------------------------===//
Spiller::~Spiller() {}
namespace {
- struct SimpleSpiller : public Spiller {
+ struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
};
}
bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
- DEBUG(std::cerr << "********** REWRITE MACHINE CODE **********\n");
- DEBUG(std::cerr << "********** Function: "
- << MF.getFunction()->getName() << '\n');
+ 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();
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) {
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()) {
}
}
- DEBUG(std::cerr << '\t' << MI);
+ DOUT << '\t' << MI;
LoadedRegs.clear();
}
}
/// 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 {
const MRegisterInfo *MRI;
const TargetInstrInfo *TII;
public:
bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
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";
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
MBB != E; ++MBB)
}
private:
void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM);
- void ClobberPhysReg(unsigned PR, std::map<int, unsigned> &SpillSlots,
- std::multimap<unsigned, int> &PhysRegs);
- void ClobberPhysRegOnly(unsigned PR, std::map<int, unsigned> &SpillSlots,
- std::multimap<unsigned, int> &PhysRegs);
- void ModifyStackSlot(int Slot, std::map<int, unsigned> &SpillSlots,
- std::multimap<unsigned, int> &PhysRegs);
};
}
/// 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.
-class AvailableSpills {
+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.
- std::map<int, unsigned> SpillSlotsAvailable;
+ // but not invalidated yet. It also tracks the instruction that last defined
+ // or used the register.
+ typedef std::pair<unsigned, MachineInstr*> SSInfo;
+ std::map<int, SSInfo> SpillSlotsAvailable;
// 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.
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; }
+
/// getSpillSlotPhysReg - If the specified stack slot is available in a
- /// physical register, return that PhysReg, otherwise return 0.
- unsigned getSpillSlotPhysReg(int Slot) const {
- std::map<int, unsigned>::const_iterator I = SpillSlotsAvailable.find(Slot);
- if (I != SpillSlotsAvailable.end())
- return I->second >> 1; // Remove the CanClobber bit.
+ /// 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<int, SSInfo>::const_iterator I = SpillSlotsAvailable.find(Slot);
+ if (I != SpillSlotsAvailable.end()) {
+ SSMI = I->second.second;
+ return I->second.first >> 1; // Remove the CanClobber bit.
+ }
return 0;
}
-
- const MRegisterInfo *getRegInfo() const { return MRI; }
+ /// UpdateLastUses - Update the last use information of all stack slots whose
+ /// values are available in the specific register.
+ void UpdateLastUse(unsigned PhysReg, MachineInstr *Use) {
+ std::multimap<unsigned, int>::iterator I =
+ PhysRegsAvailable.lower_bound(PhysReg);
+ while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
+ int Slot = I->second;
+ I++;
+
+ std::map<int, SSInfo>::iterator II = SpillSlotsAvailable.find(Slot);
+ assert(II != SpillSlotsAvailable.end() && "Slot not available!");
+ unsigned Val = II->second.first;
+ assert((Val >> 1) == PhysReg && "Bidirectional map mismatch!");
+ SpillSlotsAvailable.erase(Slot);
+ SpillSlotsAvailable[Slot] = std::make_pair(Val, Use);
+ }
+ }
+
/// 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, unsigned Reg, bool CanClobber = true) {
+ void addAvailable(int Slot, 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);
PhysRegsAvailable.insert(std::make_pair(Reg, Slot));
- SpillSlotsAvailable[Slot] = (Reg << 1) | (unsigned)CanClobber;
+ SpillSlotsAvailable[Slot] =
+ std::make_pair((Reg << 1) | (unsigned)CanClobber, MI);
- DEBUG(std::cerr << "Remembering SS#" << Slot << " in physreg "
- << MRI->getName(Reg) << "\n");
+ DOUT << "Remembering SS#" << Slot << " 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 & 1;
+ return SpillSlotsAvailable.find(Slot)->second.first & 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 we thing lives in
/// it and any of its aliases.
/// for this slot lives in (as the previous value is dead now).
void ModifyStackSlot(int Slot);
};
+}
+
+/// 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 Slot = I->second;
+ I++;
+ assert((SpillSlotsAvailable[Slot].first >> 1) == PhysReg &&
+ "Bidirectional map mismatch!");
+ SpillSlotsAvailable[Slot].first &= ~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.
while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
int Slot = I->second;
PhysRegsAvailable.erase(I++);
- assert((SpillSlotsAvailable[Slot] >> 1) == PhysReg &&
+ assert((SpillSlotsAvailable[Slot].first >> 1) == PhysReg &&
"Bidirectional map mismatch!");
SpillSlotsAvailable.erase(Slot);
- DEBUG(std::cerr << "PhysReg " << MRI->getName(PhysReg)
- << " clobbered, invalidating SS#" << Slot << "\n");
+ DOUT << "PhysReg " << MRI->getName(PhysReg)
+ << " clobbered, invalidating SS#" << Slot << "\n";
}
}
/// 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<int, unsigned>::iterator It = SpillSlotsAvailable.find(Slot);
+ std::map<int, SSInfo>::iterator It = SpillSlotsAvailable.find(Slot);
if (It == SpillSlotsAvailable.end()) return;
- unsigned Reg = It->second >> 1;
+ unsigned Reg = It->second.first >> 1;
SpillSlotsAvailable.erase(It);
// This register may hold the value of multiple stack slots, only remove this
/// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
/// is reused instead of reloaded.
- class ReuseInfo {
+ class VISIBILITY_HIDDEN ReuseInfo {
MachineInstr &MI;
std::vector<ReusedOp> Reuses;
+ BitVector PhysRegsClobbered;
public:
- ReuseInfo(MachineInstr &mi) : MI(mi) {}
+ ReuseInfo(MachineInstr &mi, const MRegisterInfo *mri) : MI(mi) {
+ PhysRegsClobbered.resize(mri->getNumRegs());
+ }
bool hasReuses() const {
return !Reuses.empty();
Reuses.push_back(ReusedOp(OpNo, StackSlot, PhysRegReused,
AssignedPhysReg, VirtReg));
}
+
+ void markClobbered(unsigned PhysReg) {
+ PhysRegsClobbered.set(PhysReg);
+ }
+
+ 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::map<int, MachineInstr*> &MaybeDeadStores) {
+ std::map<int, MachineInstr*> &MaybeDeadStores,
+ SmallSet<unsigned, 8> &Rejected) {
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.
- if (Op.PhysRegReused == PhysReg) {
+ // 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;
-
- // Remove the record for the previous reuse. We know it can never be
- // invalidated now.
- Reuses.erase(Reuses.begin()+ro);
- return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores);
+ Rejected.insert(PhysReg);
+ return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected);
} else {
// Otherwise, we might also have a problem if a previously reused
// value aliases the new register. If so, codegen the previous reload
// 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);
+ MI, Spills, MaybeDeadStores, Rejected);
MRI->loadRegFromStackSlot(*MBB, MI, NewPhysReg,
NewOp.StackSlot, AliasRC);
MI->getOperand(NewOp.Operand).setReg(NewPhysReg);
- Spills.addAvailable(NewOp.StackSlot, NewPhysReg);
+ Spills.addAvailable(NewOp.StackSlot, MI, NewPhysReg);
++NumLoads;
DEBUG(MachineBasicBlock::iterator MII = MI;
- std::cerr << '\t' << *prior(MII));
+ DOUT << '\t' << *prior(MII));
- DEBUG(std::cerr << "Reuse undone!\n");
+ DOUT << "Reuse undone!\n";
--NumReused;
// Finally, PhysReg is now available, go ahead and use it.
}
return PhysReg;
}
+
+ /// 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::map<int, MachineInstr*> &MaybeDeadStores) {
+ SmallSet<unsigned, 8> Rejected;
+ return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected);
+ }
};
}
/// register allocator is done with them. If possible, avoid reloading vregs.
void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
- DEBUG(std::cerr << MBB.getBasicBlock()->getName() << ":\n");
+ DOUT << MBB.getBasicBlock()->getName() << ":\n";
// 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);
- // 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;
-
// 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
/// ReusedOperands - Keep track of operand reuse in case we need to undo
/// reuse.
- ReuseInfo ReusedOperands(MI);
-
- DefAndUseVReg.clear();
+ ReuseInfo ReusedOperands(MI, MRI);
+
+ // Loop over all of the implicit defs, clearing them from our available
+ // sets.
+ const TargetInstrDescriptor *TID = MI.getInstrDescriptor();
+ const unsigned *ImpDef = TID->ImplicitDefs;
+ if (ImpDef) {
+ for ( ; *ImpDef; ++ImpDef) {
+ PhysRegsUsed[*ImpDef] = true;
+ ReusedOperands.markClobbered(*ImpDef);
+ Spills.ClobberPhysReg(*ImpDef);
+ }
+ }
// Process all of the spilled uses and all non spilled reg references.
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
// Ignore physregs for spilling, but remember that it is used by this
// function.
PhysRegsUsed[MO.getReg()] = true;
+ ReusedOperands.markClobbered(MO.getReg());
continue;
}
// This virtual register was assigned a physreg!
unsigned Phys = VRM.getPhys(VirtReg);
PhysRegsUsed[Phys] = true;
+ if (MO.isDef())
+ ReusedOperands.markClobbered(Phys);
MI.getOperand(i).setReg(Phys);
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;
// Check to see if this stack slot is available.
- if ((PhysReg = Spills.getSpillSlotPhysReg(StackSlot))) {
-
- // Don't reuse it for a def&use operand if we aren't allowed to change
- // the physreg!
- if (!MO.isDef() || Spills.canClobberPhysReg(StackSlot)) {
+ MachineInstr *SSMI = NULL;
+ if ((PhysReg = Spills.getSpillSlotPhysReg(StackSlot, SSMI))) {
+ // 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).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) &&
+ !ReusedOperands.isClobbered(PhysReg);
+ }
+
+ if (CanReuse) {
// If this stack slot value is already available, reuse it!
- DEBUG(std::cerr << "Reusing SS#" << StackSlot << " from physreg "
- << MRI->getName(PhysReg) << " for vreg"
- << VirtReg <<" instead of reloading into physreg "
- << MRI->getName(VRM.getPhys(VirtReg)) << "\n");
+ DOUT << "Reusing SS#" << StackSlot << " 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.
+ MachineOperand *MOK = SSMI->findRegisterUseOperand(PhysReg, true);
+ if (MOK) {
+ 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.
+ MI.getOperand(i).setIsKill();
+ Spills.UpdateLastUse(PhysReg, &MI);
+ }
+ }
+
// 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'.
// we can get at R0 or its alias.
ReusedOperands.addReuse(i, StackSlot, PhysReg,
VRM.getPhys(VirtReg), VirtReg);
+ if (ti != -1)
+ // Only mark it clobbered if this is a use&def operand.
+ ReusedOperands.markClobbered(PhysReg);
++NumReused;
continue;
}
// incoming, we don't need to inserted a dead copy.
if (DesignatedReg == PhysReg) {
// If this stack slot value is already available, reuse it!
- DEBUG(std::cerr << "Reusing SS#" << StackSlot << " from physreg "
- << MRI->getName(PhysReg) << " for vreg"
- << VirtReg
- << " instead of reloading into same physreg.\n");
+ DOUT << "Reusing SS#" << StackSlot << " from physreg "
+ << MRI->getName(PhysReg) << " for vreg"
+ << VirtReg
+ << " instead of reloading into same physreg.\n";
MI.getOperand(i).setReg(PhysReg);
+ ReusedOperands.markClobbered(PhysReg);
++NumReused;
continue;
}
MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
PhysRegsUsed[DesignatedReg] = true;
+ ReusedOperands.markClobbered(DesignatedReg);
MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC);
-
+
+ // Extend the live range of the MI that last kill the register if
+ // necessary.
+ if (SSMI) {
+ MachineOperand *MOK = SSMI->findRegisterUseOperand(PhysReg, true);
+ if (MOK) {
+ MachineInstr *CopyMI = prior(MII);
+ MachineOperand *MOU = CopyMI->findRegisterUseOperand(PhysReg);
+ MOU->setIsKill();
+ MOK->unsetIsKill();
+ Spills.UpdateLastUse(PhysReg, &MI);
+ }
+ }
+
// This invalidates DesignatedReg.
Spills.ClobberPhysReg(DesignatedReg);
- Spills.addAvailable(StackSlot, DesignatedReg);
+ Spills.addAvailable(StackSlot, &MI, DesignatedReg);
MI.getOperand(i).setReg(DesignatedReg);
- DEBUG(std::cerr << '\t' << *prior(MII));
+ DOUT << '\t' << *prior(MII);
++NumReused;
continue;
}
Spills, MaybeDeadStores);
PhysRegsUsed[PhysReg] = true;
+ ReusedOperands.markClobbered(PhysReg);
MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
// This invalidates PhysReg.
Spills.ClobberPhysReg(PhysReg);
// Any stores to this stack slot are not dead anymore.
MaybeDeadStores.erase(StackSlot);
- Spills.addAvailable(StackSlot, PhysReg);
+ Spills.addAvailable(StackSlot, &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();
++NumLoads;
MI.getOperand(i).setReg(PhysReg);
- DEBUG(std::cerr << '\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;
- Spills.ClobberPhysReg(*ImpDef);
+ DOUT << '\t' << *prior(MII);
}
- 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;
for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ++I) {
- DEBUG(std::cerr << "Folded vreg: " << I->second.first << " MR: "
- << I->second.second);
+ 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)) {
- DEBUG(std::cerr << ": No stack slot!\n");
+ DOUT << ": No stack slot!\n";
continue;
}
int SS = VRM.getStackSlot(VirtReg);
- DEBUG(std::cerr << " - StackSlot: " << SS << "\n");
+ 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 this spill slot is available, turn it into a copy (or nothing)
- // instead of leaving it as a load!
- unsigned InReg;
- if (FrameIdx == SS && (InReg = Spills.getSpillSlotPhysReg(SS))) {
- DEBUG(std::cerr << "Promoted Load To Copy: " << MI);
- MachineFunction &MF = *MBB.getParent();
- 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.
+ 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;
+ MachineFunction &MF = *MBB.getParent();
+ 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;
+
+ // Extend the live range of the MI that last kill the register if
+ // the next MI reuse it.
+ MachineOperand *MOK = SSMI->findRegisterUseOperand(InReg, true);
+ if (MOK && NextMII != MBB.end()) {
+ MachineOperand *MOU = NextMII->findRegisterUseOperand(InReg);
+ if (MOU) {
+ MOU->setIsKill();
+ MOK->unsetIsKill();
+ Spills.UpdateLastUse(InReg, &(*NextMII));
+ }
+ }
+
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ MBB.erase(&MI);
+ goto ProcessNextInst;
}
- VRM.RemoveFromFoldedVirtMap(&MI);
- MBB.erase(&MI);
- goto ProcessNextInst;
}
}
}
else {
// If we get here, the store is dead, nuke it now.
assert(VirtRegMap::isMod && "Can't be modref!");
- DEBUG(std::cerr << "Removed dead store:\t" << *MDSI->second);
+ DOUT << "Removed dead store:\t" << *MDSI->second;
MBB.erase(MDSI->second);
VRM.RemoveFromFoldedVirtMap(MDSI->second);
MaybeDeadStores.erase(MDSI);
// If the stack slot value was previously available in some other
// register, change it now. Otherwise, make the register available,
// in PhysReg.
- Spills.addAvailable(StackSlot, SrcReg, false /*don't clobber*/);
+ Spills.addAvailable(StackSlot, &MI, SrcReg, false/*don't clobber*/);
}
}
}
unsigned VirtReg = MO.getReg();
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;
- }
+ // 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);
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ Spills.disallowClobberPhysReg(VirtReg);
+ goto ProcessNextInst;
}
-
- if (!OpTakenCareOf) {
- // 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;
- DEBUG(std::cerr << "Removing now-noop copy: " << MI);
- MBB.erase(&MI);
- VRM.RemoveFromFoldedVirtMap(&MI);
- goto ProcessNextInst;
- }
- Spills.ClobberPhysReg(VirtReg);
- continue;
+
+ // 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!");
+
+ // Otherwise, if it wasn't available, remember that it is now!
+ Spills.addAvailable(FrameIdx, &MI, DestReg);
+ goto ProcessNextInst;
}
+
+ continue;
}
// 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)
+ // 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);
- else
- PhysReg = MO.getReg();
+ 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);
+ }
+ }
PhysRegsUsed[PhysReg] = true;
+ ReusedOperands.markClobbered(PhysReg);
MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
- DEBUG(std::cerr << "Store:\t" << *next(MII));
+ DOUT << "Store:\t" << *next(MII);
MI.getOperand(i).setReg(PhysReg);
- // 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;
- DEBUG(std::cerr << "Removing now-noop copy: " << MI);
- MBB.erase(&MI);
- VRM.RemoveFromFoldedVirtMap(&MI);
- goto ProcessNextInst;
- }
- }
-
// If there is a dead store to this stack slot, nuke it now.
MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
if (LastStore) {
- DEBUG(std::cerr << "Removed dead store:\t" << *LastStore);
+ DOUT << "Removed dead store:\t" << *LastStore;
++NumDSE;
MBB.erase(LastStore);
VRM.RemoveFromFoldedVirtMap(LastStore);
// in PhysReg.
Spills.ModifyStackSlot(StackSlot);
Spills.ClobberPhysReg(PhysReg);
- Spills.addAvailable(StackSlot, 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);
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ goto ProcessNextInst;
+ }
+ }
}
}
ProcessNextInst:
projects / oota-llvm.git / blobdiff