//
//===----------------------------------------------------------------------===//
//
-// 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 "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.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"),
- clEnumValEnd),
- cl::init(local));
+ 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");
+
+ 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"),
+ clEnumValEnd),
+ cl::init(local));
}
-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;
+//===----------------------------------------------------------------------===//
+// VirtRegMap implementation
+//===----------------------------------------------------------------------===//
+
+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;
+}
+
+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;
+ if (!OldMI->getOperand(OpNo).isDef()) {
+ assert(OldMI->getOperand(OpNo).isUse() && "Operand is not use or def?");
+ MRInfo = isRef;
+ } else {
+ MRInfo = OldMI->getOperand(OpNo).isUse() ? isModRef : isMod;
+ }
+
+ // add new memory reference
+ MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo)));
+}
- // add new memory reference
- mi2vMap_.insert(std::make_pair(newMI, virtReg));
+void VirtRegMap::print(std::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';
}
-std::ostream& llvm::operator<<(std::ostream& os, const VirtRegMap& vrm)
-{
- const MRegisterInfo* mri = vrm.mf_->getTarget().getRegisterInfo();
+void VirtRegMap::dump() const { print(std::cerr); }
- 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";
+
+//===----------------------------------------------------------------------===//
+// Simple Spiller Implementation
+//===----------------------------------------------------------------------===//
+
+Spiller::~Spiller() {}
+
+namespace {
+ struct SimpleSpiller : public Spiller {
+ bool runOnMachineFunction(MachineFunction& mf, const 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');
+ 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) {
+ DEBUG(std::cerr << 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() &&
+ MRegisterInfo::isVirtualRegister(MO.getReg())) {
+ unsigned VirtReg = MO.getReg();
+ unsigned PhysReg = VRM.getPhys(VirtReg);
+ if (VRM.hasStackSlot(VirtReg)) {
+ int StackSlot = VRM.getStackSlot(VirtReg);
+
+ if (MO.isUse() &&
+ std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
+ == LoadedRegs.end()) {
+ MRI.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot);
+ LoadedRegs.push_back(VirtReg);
+ ++NumLoads;
+ DEBUG(std::cerr << '\t' << *prior(MII));
+ }
+
+ if (MO.isDef()) {
+ MRI.storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot);
+ ++NumStores;
+ }
+ }
+ PhysRegsUsed[PhysReg] = true;
+ MI.SetMachineOperandReg(i, PhysReg);
+ }
+ }
+ DEBUG(std::cerr << '\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 LocalSpiller : public Spiller {
+ const MRegisterInfo *MRI;
+ const TargetInstrInfo *TII;
+ public:
+ bool runOnMachineFunction(MachineFunction &MF, const VirtRegMap &VRM) {
+ MRI = MF.getTarget().getRegisterInfo();
+ TII = MF.getTarget().getInstrInfo();
+ DEBUG(std::cerr << "\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, 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);
+ };
}
-Spiller::~Spiller()
-{
+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");
+
+ }
+}
+void LocalSpiller::ClobberPhysReg(unsigned PhysReg,
+ std::map<int, unsigned> &SpillSlots,
+ std::map<unsigned, int> &PhysRegs) {
+ for (const unsigned *AS = MRI->getAliasSet(PhysReg); *AS; ++AS)
+ ClobberPhysRegOnly(*AS, SpillSlots, PhysRegs);
+ ClobberPhysRegOnly(PhysReg, SpillSlots, PhysRegs);
}
+
+// 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;
+
+ ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr)
+ : Operand(o), StackSlot(ss), PhysRegReused(prr), AssignedPhysReg(apr) {}
+ };
+}
- 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();
+
+/// 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) {
+
+ // 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;
+
+ // PhysRegsAvailable - This is the inverse of SpillSlotsAvailable, indicating
+ // which physregs are in use holding a stack slot value.
+ std::map<unsigned, int> PhysRegsAvailable;
+
+ DEBUG(std::cerr << MBB.getBasicBlock()->getName() << ":\n");
+
+ std::vector<ReusedOp> ReusedOperands;
+
+ // 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
+ // 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.clear();
+ DefAndUseVReg.clear();
+
+ // 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() &&
+ MRegisterInfo::isVirtualRegister(MO.getReg())) {
+ unsigned VirtReg = MO.getReg();
+
+ if (!VRM.hasStackSlot(VirtReg)) {
+ // This virtual register was assigned a physreg!
+ unsigned Phys = VRM.getPhys(VirtReg);
+ PhysRegsUsed[Phys] = true;
+ MI.SetMachineOperandReg(i, Phys);
+ } else {
+ // Is this virtual register a spilled value?
+ if (MO.isUse()) {
+ int StackSlot = VRM.getStackSlot(VirtReg);
+ unsigned PhysReg;
+
+ // 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.
+ //
+ // 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)));
+ ++NumReused;
+ } else {
+ // Otherwise, reload it and remember that we have it.
+ PhysReg = VRM.getPhys(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;
+ for (const unsigned *AS = MRI->getAliasSet(PRRU); *AS; ++AS)
+ if (*AS == 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.
+ MRI->loadRegFromStackSlot(MBB, &MI, Op.AssignedPhysReg,
+ Op.StackSlot);
+ 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);
+ // This invalidates PhysReg.
+ ClobberPhysReg(PhysReg, SpillSlotsAvailable, PhysRegsAvailable);
+
+ // 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));
}
- return 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;
+ // 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 already changed 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));
}
- p2vMap_[physReg] = 0;
- dirty_[physReg] = false;
+ }
}
+ }
+ }
- 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);
- }
+ // 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);
+ }
- 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;
- }
- }
+ DEBUG(std::cerr << '\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);
+ unsigned VirtReg = I->second.first;
+ VirtRegMap::ModRef MR = I->second.second;
+ if (VRM.hasStackSlot(VirtReg)) {
+ int SS = VRM.getStackSlot(VirtReg);
+ DEBUG(std::cerr << " - StackSlot: " << SS << "\n");
+
+ // 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(MR == VirtRegMap::isMod && "Can't be modref!");
+ MBB.erase(MDSI->second);
+ MaybeDeadStores.erase(MDSI);
+ ++NumDSE;
+ }
}
- 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 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);
+ }
}
+ } else {
+ DEBUG(std::cerr << ": No stack slot!\n");
+ }
+ }
- 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_));
- }
-
- for (unsigned i = 1, e = p2vMap_.size(); i != e; ++i)
- vacateJustPhysReg(mbb, mbb.getFirstTerminator(), i);
-
+ // 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 (!OpTakenCareOf) {
+ ClobberPhysReg(VirtReg, SpillSlotsAvailable, PhysRegsAvailable);
+ TakenCareOf = true;
+ }
+ }
+
+ if (!TakenCareOf) {
+ // The only vregs left are stack slot definitions.
+ int StackSlot = VRM.getStackSlot(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);
+ DEBUG(std::cerr << "Store:\t" << *next(MII));
+ MI.SetMachineOperandReg(i, PhysReg);
+
+ // 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);
+
+ PhysRegsAvailable[PhysReg] = StackSlot;
+ SpillSlotsAvailable[StackSlot] = PhysReg;
+ DEBUG(std::cerr << "Updating SS#" << StackSlot <<" in physreg "
+ << MRI->getName(PhysReg) << " for virtreg #"
+ << VirtReg << "\n");
+
+ ++NumStores;
+ VirtReg = PhysReg;
}
- };
+ }
+ }
+ 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