//
//===----------------------------------------------------------------------===//
//
-// This file implements the virtual register map. It also implements
-// the eliminateVirtRegs() function that given a virtual register map
-// and a machine function it eliminates all virtual references by
-// replacing them with physical register references and adds spill
+// This file implements the VirtRegMap class.
+//
+// It also contains implementations of the the Spiller interface, which, given a
+// virtual register map and a machine function, eliminates all virtual
+// references by replacing them with physical register references - adding spill
// code as necessary.
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "regalloc"
+#define DEBUG_TYPE "spiller"
#include "VirtRegMap.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "Support/CommandLine.h"
-#include "Support/Debug.h"
-#include "Support/DenseMap.h"
-#include "Support/Statistic.h"
-#include "Support/STLExtras.h"
-#include <iostream>
-
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include <algorithm>
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");
-
- enum SpillerName { simple, local };
-
- cl::opt<SpillerName>
- SpillerOpt("spiller",
- cl::desc("Spiller to use: (default: local)"),
- cl::Prefix,
- cl::values(clEnumVal(simple, " simple spiller"),
- clEnumVal(local, " local spiller"),
- 0),
- cl::init(local));
+ static Statistic NumSpills("spiller", "Number of register spills");
+ static Statistic NumStores("spiller", "Number of stores added");
+ static Statistic NumLoads ("spiller", "Number of loads added");
+ static Statistic NumReused("spiller", "Number of values reused");
+ static Statistic NumDSE ("spiller", "Number of dead stores elided");
+ static Statistic NumDCE ("spiller", "Number of copies elided");
+
+ enum SpillerName { simple, local };
+
+ static cl::opt<SpillerName>
+ SpillerOpt("spiller",
+ cl::desc("Spiller to use: (default: local)"),
+ cl::Prefix,
+ cl::values(clEnumVal(simple, " simple spiller"),
+ clEnumVal(local, " local spiller"),
+ clEnumValEnd),
+ cl::init(local));
+}
+
+//===----------------------------------------------------------------------===//
+// VirtRegMap implementation
+//===----------------------------------------------------------------------===//
+
+VirtRegMap::VirtRegMap(MachineFunction &mf)
+ : TII(*mf.getTarget().getInstrInfo()), MF(mf),
+ Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT) {
+ grow();
}
-int VirtRegMap::assignVirt2StackSlot(unsigned virtReg)
-{
- assert(MRegisterInfo::isVirtualRegister(virtReg));
- assert(v2ssMap_[virtReg] == NO_STACK_SLOT &&
- "attempt to assign stack slot to already spilled register");
- const TargetRegisterClass* rc =
- mf_->getSSARegMap()->getRegClass(virtReg);
- int frameIndex = mf_->getFrameInfo()->CreateStackObject(rc);
- v2ssMap_[virtReg] = frameIndex;
- ++numSpills;
- return frameIndex;
+void VirtRegMap::grow() {
+ Virt2PhysMap.grow(MF.getSSARegMap()->getLastVirtReg());
+ Virt2StackSlotMap.grow(MF.getSSARegMap()->getLastVirtReg());
}
-void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex)
-{
- assert(MRegisterInfo::isVirtualRegister(virtReg));
- assert(v2ssMap_[virtReg] == NO_STACK_SLOT &&
- "attempt to assign stack slot to already spilled register");
- v2ssMap_[virtReg] = frameIndex;
+int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
+ assert(MRegisterInfo::isVirtualRegister(virtReg));
+ assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
+ "attempt to assign stack slot to already spilled register");
+ const TargetRegisterClass* RC = MF.getSSARegMap()->getRegClass(virtReg);
+ int frameIndex = MF.getFrameInfo()->CreateStackObject(RC->getSize(),
+ RC->getAlignment());
+ Virt2StackSlotMap[virtReg] = frameIndex;
+ ++NumSpills;
+ return frameIndex;
}
-void VirtRegMap::virtFolded(unsigned virtReg,
- MachineInstr* oldMI,
- MachineInstr* newMI)
-{
- // move previous memory references folded to new instruction
- MI2VirtMap::iterator i, e;
- std::vector<MI2VirtMap::mapped_type> regs;
- for (tie(i, e) = mi2vMap_.equal_range(oldMI); i != e; ) {
- regs.push_back(i->second);
- mi2vMap_.erase(i++);
- }
- for (unsigned i = 0, e = regs.size(); i != e; ++i)
- mi2vMap_.insert(std::make_pair(newMI, i));
+void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int frameIndex) {
+ assert(MRegisterInfo::isVirtualRegister(virtReg));
+ assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT &&
+ "attempt to assign stack slot to already spilled register");
+ Virt2StackSlotMap[virtReg] = frameIndex;
+}
- // add new memory reference
- mi2vMap_.insert(std::make_pair(newMI, virtReg));
+void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI,
+ unsigned OpNo, MachineInstr *NewMI) {
+ // Move previous memory references folded to new instruction.
+ MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(NewMI);
+ for (MI2VirtMapTy::iterator I = MI2VirtMap.lower_bound(OldMI),
+ E = MI2VirtMap.end(); I != E && I->first == OldMI; ) {
+ MI2VirtMap.insert(IP, std::make_pair(NewMI, I->second));
+ MI2VirtMap.erase(I++);
+ }
+
+ ModRef MRInfo;
+ 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 = isRef;
+ }
+
+ // add new memory reference
+ MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo)));
}
-std::ostream& llvm::operator<<(std::ostream& os, const VirtRegMap& vrm)
-{
- const MRegisterInfo* mri = vrm.mf_->getTarget().getRegisterInfo();
+void VirtRegMap::print(std::ostream &OS) const {
+ OStream LOS(OS);
+ print(LOS);
+}
- std::cerr << "********** REGISTER MAP **********\n";
- for (unsigned i = MRegisterInfo::FirstVirtualRegister,
- e = vrm.mf_->getSSARegMap()->getLastVirtReg(); i <= e; ++i) {
- if (vrm.v2pMap_[i] != VirtRegMap::NO_PHYS_REG)
- std::cerr << "[reg" << i << " -> "
- << mri->getName(vrm.v2pMap_[i]) << "]\n";
+void VirtRegMap::print(OStream &OS) const {
+ const MRegisterInfo* MRI = MF.getTarget().getRegisterInfo();
+
+ OS << "********** REGISTER MAP **********\n";
+ for (unsigned i = MRegisterInfo::FirstVirtualRegister,
+ e = MF.getSSARegMap()->getLastVirtReg(); i <= e; ++i) {
+ if (Virt2PhysMap[i] != (unsigned)VirtRegMap::NO_PHYS_REG)
+ OS << "[reg" << i << " -> " << MRI->getName(Virt2PhysMap[i]) << "]\n";
+
+ }
+
+ for (unsigned i = MRegisterInfo::FirstVirtualRegister,
+ e = MF.getSSARegMap()->getLastVirtReg(); i <= e; ++i)
+ if (Virt2StackSlotMap[i] != VirtRegMap::NO_STACK_SLOT)
+ OS << "[reg" << i << " -> fi#" << Virt2StackSlotMap[i] << "]\n";
+ OS << '\n';
+}
+
+void VirtRegMap::dump() const {
+ OStream OS = DOUT;
+ print(OS);
+}
+
+
+//===----------------------------------------------------------------------===//
+// Simple Spiller Implementation
+//===----------------------------------------------------------------------===//
+
+Spiller::~Spiller() {}
+
+namespace {
+ struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
+ bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
+ };
+}
+
+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
+ // operands). This is always smaller than the number of operands to the
+ // current machine instr, so it should be small.
+ std::vector<unsigned> LoadedRegs;
+
+ for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
+ MBBI != E; ++MBBI) {
+ DOUT << MBBI->getBasicBlock()->getName() << ":\n";
+ MachineBasicBlock &MBB = *MBBI;
+ for (MachineBasicBlock::iterator MII = MBB.begin(),
+ E = MBB.end(); MII != E; ++MII) {
+ MachineInstr &MI = *MII;
+ for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI.getOperand(i);
+ if (MO.isRegister() && MO.getReg())
+ if (MRegisterInfo::isVirtualRegister(MO.getReg())) {
+ unsigned VirtReg = MO.getReg();
+ unsigned PhysReg = VRM.getPhys(VirtReg);
+ if (VRM.hasStackSlot(VirtReg)) {
+ int StackSlot = VRM.getStackSlot(VirtReg);
+ const TargetRegisterClass* RC =
+ MF.getSSARegMap()->getRegClass(VirtReg);
+
+ if (MO.isUse() &&
+ std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
+ == LoadedRegs.end()) {
+ MRI.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
+ LoadedRegs.push_back(VirtReg);
+ ++NumLoads;
+ DOUT << '\t' << *prior(MII);
+ }
+
+ if (MO.isDef()) {
+ MRI.storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
+ ++NumStores;
+ }
+ }
+ PhysRegsUsed[PhysReg] = true;
+ MI.getOperand(i).setReg(PhysReg);
+ } else {
+ PhysRegsUsed[MO.getReg()] = true;
+ }
+ }
+
+ DOUT << '\t' << MI;
+ LoadedRegs.clear();
}
- for (unsigned i = MRegisterInfo::FirstVirtualRegister,
- e = vrm.mf_->getSSARegMap()->getLastVirtReg(); i <= e; ++i) {
- if (vrm.v2ssMap_[i] != VirtRegMap::NO_STACK_SLOT)
- std::cerr << "[reg" << i << " -> fi#"
- << vrm.v2ssMap_[i] << "]\n";
+ }
+ return true;
+}
+
+//===----------------------------------------------------------------------===//
+// Local Spiller Implementation
+//===----------------------------------------------------------------------===//
+
+namespace {
+ /// 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 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();
+ DOUT << "\n**** Local spiller rewriting function '"
+ << MF.getFunction()->getName() << "':\n";
+
+ for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
+ MBB != E; ++MBB)
+ RewriteMBB(*MBB, VRM);
+ return true;
}
- return std::cerr << '\n';
+ 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);
+ };
+}
+
+/// 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.
+///
+/// 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.
+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;
+
+ // 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) {
+ }
+
+ /// 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.
+ return 0;
+ }
+
+ const MRegisterInfo *getRegInfo() const { return MRI; }
+
+ /// 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) {
+ // 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;
+
+ 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;
+ }
+
+ /// 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.
+ 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);
+};
+}
+
+/// 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] >> 1) == PhysReg &&
+ "Bidirectional map mismatch!");
+ SpillSlotsAvailable[Slot] &= ~1;
+ DOUT << "PhysReg " << MRI->getName(PhysReg)
+ << " copied, it is available for use but can no longer be modified\n";
+ }
}
-Spiller::~Spiller()
-{
+/// 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 Slot = I->second;
+ PhysRegsAvailable.erase(I++);
+ assert((SpillSlotsAvailable[Slot] >> 1) == PhysReg &&
+ "Bidirectional map mismatch!");
+ SpillSlotsAvailable.erase(Slot);
+ DOUT << "PhysReg " << MRI->getName(PhysReg)
+ << " clobbered, invalidating SS#" << Slot << "\n";
+ }
+}
+
+/// 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);
+ 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<int, unsigned>::iterator It = SpillSlotsAvailable.find(Slot);
+ if (It == SpillSlotsAvailable.end()) return;
+ unsigned Reg = It->second >> 1;
+ SpillSlotsAvailable.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 == Slot) break;
+ }
+ PhysRegsAvailable.erase(I);
}
+
+
+// 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 {
+ struct ReusedOp {
+ // The MachineInstr operand that reused an available value.
+ unsigned Operand;
+
+ // StackSlot - The spill slot of the value being reused.
+ unsigned StackSlot;
+
+ // PhysRegReused - The physical register the value was available in.
+ unsigned PhysRegReused;
+
+ // AssignedPhysReg - The physreg that was assigned for use by the reload.
+ unsigned AssignedPhysReg;
+
+ // VirtReg - The virtual register itself.
+ unsigned VirtReg;
+
+ ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
+ unsigned vreg)
+ : Operand(o), StackSlot(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;
+ bool *PhysRegsClobbered;
+ public:
+ ReuseInfo(MachineInstr &mi, const MRegisterInfo *mri) : MI(mi) {
+ PhysRegsClobbered = new bool[mri->getNumRegs()];
+ std::fill(PhysRegsClobbered, PhysRegsClobbered+mri->getNumRegs(), false);
+ }
+ ~ReuseInfo() {
+ delete[] PhysRegsClobbered;
+ }
+
+ 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 StackSlot,
+ 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, StackSlot, PhysRegReused,
+ AssignedPhysReg, VirtReg));
+ }
- class SimpleSpiller : public Spiller {
- public:
- bool runOnMachineFunction(MachineFunction& mf, const VirtRegMap& vrm) {
- DEBUG(std::cerr << "********** REWRITE MACHINE CODE **********\n");
- DEBUG(std::cerr << "********** Function: "
- << mf.getFunction()->getName() << '\n');
- const TargetMachine& tm = mf.getTarget();
- const MRegisterInfo& mri = *tm.getRegisterInfo();
-
- typedef DenseMap<bool, VirtReg2IndexFunctor> Loaded;
- Loaded loaded;
-
- for (MachineFunction::iterator mbbi = mf.begin(),
- mbbe = mf.end(); mbbi != mbbe; ++mbbi) {
- DEBUG(std::cerr << mbbi->getBasicBlock()->getName() << ":\n");
- for (MachineBasicBlock::iterator mii = mbbi->begin(),
- mie = mbbi->end(); mii != mie; ++mii) {
- loaded.grow(mf.getSSARegMap()->getLastVirtReg());
- for (unsigned i = 0,e = mii->getNumOperands(); i != e; ++i){
- MachineOperand& mop = mii->getOperand(i);
- if (mop.isRegister() && mop.getReg() &&
- MRegisterInfo::isVirtualRegister(mop.getReg())) {
- unsigned virtReg = mop.getReg();
- unsigned physReg = vrm.getPhys(virtReg);
- if (mop.isUse() &&
- vrm.hasStackSlot(mop.getReg()) &&
- !loaded[virtReg]) {
- mri.loadRegFromStackSlot(
- *mbbi,
- mii,
- physReg,
- vrm.getStackSlot(virtReg),
- mf.getSSARegMap()->getRegClass(virtReg));
- loaded[virtReg] = true;
- DEBUG(std::cerr << '\t';
- prior(mii)->print(std::cerr, &tm));
- ++numLoads;
- }
- if (mop.isDef() &&
- vrm.hasStackSlot(mop.getReg())) {
- mri.storeRegToStackSlot(
- *mbbi,
- next(mii),
- physReg,
- vrm.getStackSlot(virtReg),
- mf.getSSARegMap()->getRegClass(virtReg));
- ++numStores;
- }
- mii->SetMachineOperandReg(i, physReg);
- }
- }
- DEBUG(std::cerr << '\t'; mii->print(std::cerr, &tm));
- loaded.clear();
- }
- }
- return true;
- }
- };
-
- class LocalSpiller : public Spiller {
- typedef std::vector<unsigned> Phys2VirtMap;
- typedef std::vector<bool> PhysFlag;
- typedef DenseMap<MachineInstr*, VirtReg2IndexFunctor> Virt2MI;
-
- MachineFunction* mf_;
- const TargetMachine* tm_;
- const TargetInstrInfo* tii_;
- const MRegisterInfo* mri_;
- const VirtRegMap* vrm_;
- Phys2VirtMap p2vMap_;
- PhysFlag dirty_;
- Virt2MI lastDef_;
-
- public:
- bool runOnMachineFunction(MachineFunction& mf, const VirtRegMap& vrm) {
- mf_ = &mf;
- tm_ = &mf_->getTarget();
- tii_ = tm_->getInstrInfo();
- mri_ = tm_->getRegisterInfo();
- vrm_ = &vrm;
- p2vMap_.assign(mri_->getNumRegs(), 0);
- dirty_.assign(mri_->getNumRegs(), false);
-
- DEBUG(std::cerr << "********** REWRITE MACHINE CODE **********\n");
- DEBUG(std::cerr << "********** Function: "
- << mf_->getFunction()->getName() << '\n');
-
- for (MachineFunction::iterator mbbi = mf_->begin(),
- mbbe = mf_->end(); mbbi != mbbe; ++mbbi) {
- lastDef_.grow(mf_->getSSARegMap()->getLastVirtReg());
- DEBUG(std::cerr << mbbi->getBasicBlock()->getName() << ":\n");
- eliminateVirtRegsInMbb(*mbbi);
- // clear map, dirty flag and last ref
- p2vMap_.assign(p2vMap_.size(), 0);
- dirty_.assign(dirty_.size(), false);
- lastDef_.clear();
- }
- return true;
- }
+ void markClobbered(unsigned PhysReg) {
+ PhysRegsClobbered[PhysReg] = true;
+ }
- private:
- void vacateJustPhysReg(MachineBasicBlock& mbb,
- MachineBasicBlock::iterator mii,
- unsigned physReg) {
- unsigned virtReg = p2vMap_[physReg];
- if (dirty_[physReg] && vrm_->hasStackSlot(virtReg)) {
- assert(lastDef_[virtReg] && "virtual register is mapped "
- "to a register and but was not defined!");
- MachineBasicBlock::iterator lastDef = lastDef_[virtReg];
- MachineBasicBlock::iterator nextLastRef = next(lastDef);
- mri_->storeRegToStackSlot(*lastDef->getParent(),
- nextLastRef,
- physReg,
- vrm_->getStackSlot(virtReg),
- mri_->getRegClass(physReg));
- ++numStores;
- DEBUG(std::cerr << "added: ";
- prior(nextLastRef)->print(std::cerr, tm_);
- std::cerr << "after: ";
- lastDef->print(std::cerr, tm_));
- lastDef_[virtReg] = 0;
- }
- p2vMap_[physReg] = 0;
- dirty_[physReg] = false;
+ bool isClobbered(unsigned PhysReg) const {
+ return PhysRegsClobbered[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) {
+ 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) {
+ // Yup, use the reload register that we didn't use before.
+ unsigned NewReg = Op.AssignedPhysReg;
+ return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores);
+ } 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);
+
+ MRI->loadRegFromStackSlot(*MBB, MI, NewPhysReg,
+ NewOp.StackSlot, AliasRC);
+ 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, NewPhysReg);
+ ++NumLoads;
+ DEBUG(MachineBasicBlock::iterator MII = MI;
+ DOUT << '\t' << *prior(MII));
+
+ DOUT << "Reuse undone!\n";
+ --NumReused;
+
+ // Finally, PhysReg is now available, go ahead and use it.
+ return PhysReg;
+ }
}
+ }
+ return PhysReg;
+ }
+ };
+}
+
- void vacatePhysReg(MachineBasicBlock& mbb,
- MachineBasicBlock::iterator mii,
- unsigned physReg) {
- vacateJustPhysReg(mbb, mii, physReg);
- for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as)
- vacateJustPhysReg(mbb, mii, *as);
+/// 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";
+
+ // 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;
+
+ bool *PhysRegsUsed = MBB.getParent()->getUsedPhysregs();
+
+ for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
+ MII != E; ) {
+ MachineInstr &MI = *MII;
+ MachineBasicBlock::iterator NextMII = MII; ++NextMII;
+
+ /// ReusedOperands - Keep track of operand reuse in case we need to undo
+ /// reuse.
+ 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) {
+ MachineOperand &MO = MI.getOperand(i);
+ if (!MO.isRegister() || MO.getReg() == 0)
+ continue; // Ignore non-register operands.
+
+ if (MRegisterInfo::isPhysicalRegister(MO.getReg())) {
+ // Ignore physregs for spilling, but remember that it is used by this
+ // function.
+ PhysRegsUsed[MO.getReg()] = true;
+ ReusedOperands.markClobbered(MO.getReg());
+ continue;
+ }
+
+ assert(MRegisterInfo::isVirtualRegister(MO.getReg()) &&
+ "Not a virtual or a physical register?");
+
+ unsigned VirtReg = MO.getReg();
+ if (!VRM.hasStackSlot(VirtReg)) {
+ // 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;
+ }
+
+ // This virtual register is now known to be a spilled value.
+ if (!MO.isUse())
+ continue; // Handle defs in the loop below (handle use&def here though)
+
+ int StackSlot = VRM.getStackSlot(VirtReg);
+ unsigned PhysReg;
+
+ // Check to see if this stack slot is available.
+ if ((PhysReg = Spills.getSpillSlotPhysReg(StackSlot))) {
+
+ // 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 is 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!
+ 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);
+
+ // 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, 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;
}
+
+ // Otherwise we have a situation where we have a two-address instruction
+ // whose mod/ref operand needs to be reloaded. This reload is already
+ // available in some register "PhysReg", but if we used PhysReg as the
+ // operand to our 2-addr instruction, the instruction would modify
+ // PhysReg. This isn't cool if something later uses PhysReg and expects
+ // to get its initial value.
+ //
+ // To avoid this problem, and to avoid doing a load right after a store,
+ // we emit a copy from PhysReg into the designated register for this
+ // operand.
+ unsigned DesignatedReg = VRM.getPhys(VirtReg);
+ assert(DesignatedReg && "Must map virtreg to physreg!");
+
+ // Note that, if we reused a register for a previous operand, the
+ // register we want to reload into might not actually be
+ // available. If this occurs, use the register indicated by the
+ // reuser.
+ if (ReusedOperands.hasReuses())
+ DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI,
+ Spills, MaybeDeadStores);
+
+ // 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!
+ 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;
+ }
+
+ const TargetRegisterClass* RC =
+ MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
+
+ PhysRegsUsed[DesignatedReg] = true;
+ ReusedOperands.markClobbered(DesignatedReg);
+ MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC);
+
+ // This invalidates DesignatedReg.
+ Spills.ClobberPhysReg(DesignatedReg);
+
+ Spills.addAvailable(StackSlot, DesignatedReg);
+ MI.getOperand(i).setReg(DesignatedReg);
+ DOUT << '\t' << *prior(MII);
+ ++NumReused;
+ continue;
+ }
+
+ // 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);
+
+ // Note that, if we reused a register for a previous operand, the
+ // register we want to reload into might not actually be
+ // available. If this occurs, use the register indicated by the
+ // reuser.
+ if (ReusedOperands.hasReuses())
+ PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
+ Spills, MaybeDeadStores);
+
+ 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);
+ ++NumLoads;
+ MI.getOperand(i).setReg(PhysReg);
+ DOUT << '\t' << *prior(MII);
+ }
- void handleUse(MachineBasicBlock& mbb,
- MachineBasicBlock::iterator mii,
- unsigned virtReg,
- unsigned physReg) {
- // check if we are replacing a previous mapping
- if (p2vMap_[physReg] != virtReg) {
- vacatePhysReg(mbb, mii, physReg);
- p2vMap_[physReg] = virtReg;
- // load if necessary
- if (vrm_->hasStackSlot(virtReg)) {
- mri_->loadRegFromStackSlot(mbb, mii, physReg,
- vrm_->getStackSlot(virtReg),
- mri_->getRegClass(physReg));
- ++numLoads;
- DEBUG(std::cerr << "added: ";
- prior(mii)->print(std::cerr, tm_));
- lastDef_[virtReg] = mii;
- }
+ 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) {
+ 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)) {
+ DOUT << ": No stack slot!\n";
+ continue;
+ }
+ int SS = VRM.getStackSlot(VirtReg);
+ 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!
+ if (unsigned InReg = Spills.getSpillSlotPhysReg(SS)) {
+ 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.
+ }
+ VRM.RemoveFromFoldedVirtMap(&MI);
+ MBB.erase(&MI);
+ goto ProcessNextInst;
}
+ }
}
-
- void handleDef(MachineBasicBlock& mbb,
- MachineBasicBlock::iterator mii,
- unsigned virtReg,
- unsigned physReg) {
- // check if we are replacing a previous mapping
- if (p2vMap_[physReg] != virtReg)
- vacatePhysReg(mbb, mii, physReg);
-
- p2vMap_[physReg] = virtReg;
- dirty_[physReg] = true;
- lastDef_[virtReg] = mii;
+ }
+
+ // 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 {
+ // 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);
+ ++NumDSE;
+ }
+ }
+
+ // 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);
+
+ // 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, SrcReg, false /*don't clobber*/);
+ }
}
+ }
+ }
- void eliminateVirtRegsInMbb(MachineBasicBlock& mbb) {
- for (MachineBasicBlock::iterator mii = mbb.begin(),
- mie = mbb.end(); mii != mie; ++mii) {
-
- // if we have references to memory operands make sure
- // we clear all physical registers that may contain
- // the value of the spilled virtual register
- VirtRegMap::MI2VirtMap::const_iterator i, e;
- for (tie(i, e) = vrm_->getFoldedVirts(mii); i != e; ++i) {
- if (vrm_->hasPhys(i->second))
- vacateJustPhysReg(mbb, mii, vrm_->getPhys(i->second));
- }
-
- // rewrite all used operands
- for (unsigned i = 0, e = mii->getNumOperands(); i != e; ++i) {
- MachineOperand& op = mii->getOperand(i);
- if (op.isRegister() && op.getReg() && op.isUse() &&
- MRegisterInfo::isVirtualRegister(op.getReg())) {
- unsigned virtReg = op.getReg();
- unsigned physReg = vrm_->getPhys(virtReg);
- handleUse(mbb, mii, virtReg, physReg);
- mii->SetMachineOperandReg(i, physReg);
- // mark as dirty if this is def&use
- if (op.isDef()) {
- dirty_[physReg] = true;
- lastDef_[virtReg] = mii;
- }
- }
- }
-
- // spill implicit physical register defs
- const TargetInstrDescriptor& tid = tii_->get(mii->getOpcode());
- for (const unsigned* id = tid.ImplicitDefs; *id; ++id)
- vacatePhysReg(mbb, mii, *id);
-
- // spill explicit physical register defs
- for (unsigned i = 0, e = mii->getNumOperands(); i != e; ++i) {
- MachineOperand& op = mii->getOperand(i);
- if (op.isRegister() && op.getReg() && !op.isUse() &&
- MRegisterInfo::isPhysicalRegister(op.getReg()))
- vacatePhysReg(mbb, mii, op.getReg());
- }
-
- // rewrite def operands (def&use was handled with the
- // uses so don't check for those here)
- for (unsigned i = 0, e = mii->getNumOperands(); i != e; ++i) {
- MachineOperand& op = mii->getOperand(i);
- if (op.isRegister() && op.getReg() && !op.isUse())
- if (MRegisterInfo::isPhysicalRegister(op.getReg()))
- vacatePhysReg(mbb, mii, op.getReg());
- else {
- unsigned physReg = vrm_->getPhys(op.getReg());
- handleDef(mbb, mii, op.getReg(), physReg);
- mii->SetMachineOperandReg(i, physReg);
- }
- }
-
- DEBUG(std::cerr << '\t'; mii->print(std::cerr, tm_));
- }
+ // Process all of the spilled defs.
+ for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI.getOperand(i);
+ if (MO.isRegister() && MO.getReg() && MO.isDef()) {
+ unsigned VirtReg = MO.getReg();
+
+ if (!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);
+ 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!");
+
+ // Otherwise, if it wasn't available, remember that it is now!
+ Spills.addAvailable(FrameIdx, DestReg);
+ goto ProcessNextInst;
+ }
+
+ continue;
+ }
- for (unsigned i = 1, e = p2vMap_.size(); i != e; ++i)
- vacateJustPhysReg(mbb, mbb.getFirstTerminator(), i);
+ // The only vregs left are stack slot definitions.
+ int StackSlot = VRM.getStackSlot(VirtReg);
+ const TargetRegisterClass *RC =
+ MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
+
+ // If this def is part of a two-address operand, make sure to execute
+ // the store from the correct physical register.
+ unsigned PhysReg;
+ int TiedOp = MI.getInstrDescriptor()->findTiedToSrcOperand(i);
+ if (TiedOp != -1)
+ PhysReg = MI.getOperand(TiedOp).getReg();
+ else {
+ PhysReg = VRM.getPhys(VirtReg);
+ if (ReusedOperands.isClobbered(PhysReg)) {
+ // Another def has taken the assigned physreg. It must have been a
+ // use&def which got it due to reuse. Undo the reuse!
+ PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
+ Spills, MaybeDeadStores);
+ }
+ }
+ PhysRegsUsed[PhysReg] = true;
+ ReusedOperands.markClobbered(PhysReg);
+ MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
+ 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;
+ DOUT << "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) {
+ 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, PhysReg);
+ ++NumStores;
+ }
+ }
+ ProcessNextInst:
+ MII = NextMII;
+ }
}
-llvm::Spiller* llvm::createSpiller()
-{
- switch (SpillerOpt) {
- default:
- std::cerr << "no spiller selected";
- abort();
- case local:
- return new LocalSpiller();
- case simple:
- return new SimpleSpiller();
- }
+
+
+llvm::Spiller* llvm::createSpiller() {
+ switch (SpillerOpt) {
+ default: assert(0 && "Unreachable!");
+ case local:
+ return new LocalSpiller();
+ case simple:
+ return new SimpleSpiller();
+ }
}
projects / oota-llvm.git / blobdiff