X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;ds=sidebyside;f=lib%2FCodeGen%2FVirtRegMap.cpp;h=7d3b0cea1c150ccc237cc22db99d1f3d932d4a51;hb=4ceab42509518746afef0370e7aba230736a80f5;hp=9cb580b9f0ab7385edef9c9226305a70f45c8cd5;hpb=d62e06c53b8b7e555617dc9b24b98c007d63de5d;p=oota-llvm.git diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp index 9cb580b9f0a..7d3b0cea1c1 100644 --- a/lib/CodeGen/VirtRegMap.cpp +++ b/lib/CodeGen/VirtRegMap.cpp @@ -9,102 +9,102 @@ // // This file implements the VirtRegMap class. // -// It also contains implementations of the the Spiller interface, which, given a +// It also contains implementations of 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 "spiller" -#include "VirtRegMap.h" -#include "llvm/Function.h" +#include "llvm/CodeGen/VirtRegMap.h" +#include "LiveDebugVariables.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SparseSet.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/CodeGen/LiveIntervalAnalysis.h" +#include "llvm/CodeGen/LiveStackAnalysis.h" #include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/CodeGen/Passes.h" +#include "llvm/IR/Function.h" #include "llvm/Support/CommandLine.h" -#include "llvm/Support/Debug.h" #include "llvm/Support/Compiler.h" -#include "llvm/ADT/BitVector.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/ADT/SmallSet.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/Target/TargetSubtargetInfo.h" #include using namespace llvm; -STATISTIC(NumSpills , "Number of register spills"); -STATISTIC(NumPSpills , "Number of physical register spills"); -STATISTIC(NumReMats , "Number of re-materialization"); -STATISTIC(NumDRM , "Number of re-materializable defs elided"); -STATISTIC(NumStores , "Number of stores added"); -STATISTIC(NumLoads , "Number of loads added"); -STATISTIC(NumReused , "Number of values reused"); -STATISTIC(NumDSE , "Number of dead stores elided"); -STATISTIC(NumDCE , "Number of copies elided"); -STATISTIC(NumDSS , "Number of dead spill slots removed"); -STATISTIC(NumCommutes, "Number of instructions commuted"); +#define DEBUG_TYPE "regalloc" -namespace { - enum SpillerName { simple, local }; -} - -static cl::opt -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(NumSpillSlots, "Number of spill slots allocated"); +STATISTIC(NumIdCopies, "Number of identity moves eliminated after rewriting"); //===----------------------------------------------------------------------===// // VirtRegMap implementation //===----------------------------------------------------------------------===// -VirtRegMap::VirtRegMap(MachineFunction &mf) - : TII(*mf.getTarget().getInstrInfo()), MF(mf), - Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT), - Virt2ReMatIdMap(NO_STACK_SLOT), Virt2SplitMap(0), - Virt2SplitKillMap(0), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1), - LowSpillSlot(NO_STACK_SLOT), HighSpillSlot(NO_STACK_SLOT) { - SpillSlotToUsesMap.resize(8); - ImplicitDefed.resize(MF.getRegInfo().getLastVirtReg()+1- - TargetRegisterInfo::FirstVirtualRegister); +char VirtRegMap::ID = 0; + +INITIALIZE_PASS(VirtRegMap, "virtregmap", "Virtual Register Map", false, false) + +bool VirtRegMap::runOnMachineFunction(MachineFunction &mf) { + MRI = &mf.getRegInfo(); + TII = mf.getSubtarget().getInstrInfo(); + TRI = mf.getSubtarget().getRegisterInfo(); + MF = &mf; + + Virt2PhysMap.clear(); + Virt2StackSlotMap.clear(); + Virt2SplitMap.clear(); + grow(); + return false; } void VirtRegMap::grow() { - unsigned LastVirtReg = MF.getRegInfo().getLastVirtReg(); - Virt2PhysMap.grow(LastVirtReg); - Virt2StackSlotMap.grow(LastVirtReg); - Virt2ReMatIdMap.grow(LastVirtReg); - Virt2SplitMap.grow(LastVirtReg); - Virt2SplitKillMap.grow(LastVirtReg); - ReMatMap.grow(LastVirtReg); - ImplicitDefed.resize(LastVirtReg-TargetRegisterInfo::FirstVirtualRegister+1); + unsigned NumRegs = MF->getRegInfo().getNumVirtRegs(); + Virt2PhysMap.resize(NumRegs); + Virt2StackSlotMap.resize(NumRegs); + Virt2SplitMap.resize(NumRegs); +} + +unsigned VirtRegMap::createSpillSlot(const TargetRegisterClass *RC) { + int SS = MF->getFrameInfo()->CreateSpillStackObject(RC->getSize(), + RC->getAlignment()); + ++NumSpillSlots; + return SS; +} + +bool VirtRegMap::hasPreferredPhys(unsigned VirtReg) { + unsigned Hint = MRI->getSimpleHint(VirtReg); + if (!Hint) + return 0; + if (TargetRegisterInfo::isVirtualRegister(Hint)) + Hint = getPhys(Hint); + return getPhys(VirtReg) == Hint; +} + +bool VirtRegMap::hasKnownPreference(unsigned VirtReg) { + std::pair Hint = MRI->getRegAllocationHint(VirtReg); + if (TargetRegisterInfo::isPhysicalRegister(Hint.second)) + return true; + if (TargetRegisterInfo::isVirtualRegister(Hint.second)) + return hasPhys(Hint.second); + return false; } int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) { assert(TargetRegisterInfo::isVirtualRegister(virtReg)); assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT && "attempt to assign stack slot to already spilled register"); - const TargetRegisterClass* RC = MF.getRegInfo().getRegClass(virtReg); - int SS = MF.getFrameInfo()->CreateStackObject(RC->getSize(), - RC->getAlignment()); - if (LowSpillSlot == NO_STACK_SLOT) - LowSpillSlot = SS; - if (HighSpillSlot == NO_STACK_SLOT || SS > HighSpillSlot) - HighSpillSlot = SS; - unsigned Idx = SS-LowSpillSlot; - while (Idx >= SpillSlotToUsesMap.size()) - SpillSlotToUsesMap.resize(SpillSlotToUsesMap.size()*2); - Virt2StackSlotMap[virtReg] = SS; - ++NumSpills; - return SS; + const TargetRegisterClass* RC = MF->getRegInfo().getRegClass(virtReg); + return Virt2StackSlotMap[virtReg] = createSpillSlot(RC); } void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int SS) { @@ -112,1765 +112,345 @@ void VirtRegMap::assignVirt2StackSlot(unsigned virtReg, int SS) { assert(Virt2StackSlotMap[virtReg] == NO_STACK_SLOT && "attempt to assign stack slot to already spilled register"); assert((SS >= 0 || - (SS >= MF.getFrameInfo()->getObjectIndexBegin())) && + (SS >= MF->getFrameInfo()->getObjectIndexBegin())) && "illegal fixed frame index"); Virt2StackSlotMap[virtReg] = SS; } -int VirtRegMap::assignVirtReMatId(unsigned virtReg) { - assert(TargetRegisterInfo::isVirtualRegister(virtReg)); - assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT && - "attempt to assign re-mat id to already spilled register"); - Virt2ReMatIdMap[virtReg] = ReMatId; - return ReMatId++; -} - -void VirtRegMap::assignVirtReMatId(unsigned virtReg, int id) { - assert(TargetRegisterInfo::isVirtualRegister(virtReg)); - assert(Virt2ReMatIdMap[virtReg] == NO_STACK_SLOT && - "attempt to assign re-mat id to already spilled register"); - Virt2ReMatIdMap[virtReg] = id; -} - -int VirtRegMap::getEmergencySpillSlot(const TargetRegisterClass *RC) { - std::map::iterator I = - EmergencySpillSlots.find(RC); - if (I != EmergencySpillSlots.end()) - return I->second; - int SS = MF.getFrameInfo()->CreateStackObject(RC->getSize(), - RC->getAlignment()); - if (LowSpillSlot == NO_STACK_SLOT) - LowSpillSlot = SS; - if (HighSpillSlot == NO_STACK_SLOT || SS > HighSpillSlot) - HighSpillSlot = SS; - EmergencySpillSlots[RC] = SS; - return SS; -} - -void VirtRegMap::addSpillSlotUse(int FI, MachineInstr *MI) { - if (!MF.getFrameInfo()->isFixedObjectIndex(FI)) { - // If FI < LowSpillSlot, this stack reference was produced by - // instruction selection and is not a spill - if (FI >= LowSpillSlot) { - assert(FI >= 0 && "Spill slot index should not be negative!"); - assert((unsigned)FI-LowSpillSlot < SpillSlotToUsesMap.size() - && "Invalid spill slot"); - SpillSlotToUsesMap[FI-LowSpillSlot].insert(MI); +void VirtRegMap::print(raw_ostream &OS, const Module*) const { + OS << "********** REGISTER MAP **********\n"; + for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) { + unsigned Reg = TargetRegisterInfo::index2VirtReg(i); + if (Virt2PhysMap[Reg] != (unsigned)VirtRegMap::NO_PHYS_REG) { + OS << '[' << PrintReg(Reg, TRI) << " -> " + << PrintReg(Virt2PhysMap[Reg], TRI) << "] " + << TRI->getRegClassName(MRI->getRegClass(Reg)) << "\n"; } } -} - -void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *OldMI, - MachineInstr *NewMI, ModRef MRInfo) { - // 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++); - } - - // add new memory reference - MI2VirtMap.insert(IP, std::make_pair(NewMI, std::make_pair(VirtReg, MRInfo))); -} - -void VirtRegMap::virtFolded(unsigned VirtReg, MachineInstr *MI, ModRef MRInfo) { - MI2VirtMapTy::iterator IP = MI2VirtMap.lower_bound(MI); - MI2VirtMap.insert(IP, std::make_pair(MI, std::make_pair(VirtReg, MRInfo))); -} - -void VirtRegMap::RemoveMachineInstrFromMaps(MachineInstr *MI) { - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isFI()) - continue; - int FI = MO.getIndex(); - if (MF.getFrameInfo()->isFixedObjectIndex(FI)) - continue; - // This stack reference was produced by instruction selection and - // is not a spill - if (FI < LowSpillSlot) - continue; - assert((unsigned)FI-LowSpillSlot < SpillSlotToUsesMap.size() - && "Invalid spill slot"); - SpillSlotToUsesMap[FI-LowSpillSlot].erase(MI); - } - MI2VirtMap.erase(MI); - SpillPt2VirtMap.erase(MI); - RestorePt2VirtMap.erase(MI); - EmergencySpillMap.erase(MI); -} - -void VirtRegMap::print(std::ostream &OS) const { - const TargetRegisterInfo* TRI = MF.getTarget().getRegisterInfo(); - OS << "********** REGISTER MAP **********\n"; - for (unsigned i = TargetRegisterInfo::FirstVirtualRegister, - e = MF.getRegInfo().getLastVirtReg(); i <= e; ++i) { - if (Virt2PhysMap[i] != (unsigned)VirtRegMap::NO_PHYS_REG) - OS << "[reg" << i << " -> " << TRI->getName(Virt2PhysMap[i]) - << "]\n"; + for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) { + unsigned Reg = TargetRegisterInfo::index2VirtReg(i); + if (Virt2StackSlotMap[Reg] != VirtRegMap::NO_STACK_SLOT) { + OS << '[' << PrintReg(Reg, TRI) << " -> fi#" << Virt2StackSlotMap[Reg] + << "] " << TRI->getRegClassName(MRI->getRegClass(Reg)) << "\n"; + } } - - for (unsigned i = TargetRegisterInfo::FirstVirtualRegister, - e = MF.getRegInfo().getLastVirtReg(); i <= e; ++i) - if (Virt2StackSlotMap[i] != VirtRegMap::NO_STACK_SLOT) - OS << "[reg" << i << " -> fi#" << Virt2StackSlotMap[i] << "]\n"; OS << '\n'; } +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void VirtRegMap::dump() const { - print(cerr); -} - - -//===----------------------------------------------------------------------===// -// 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 TargetInstrInfo &TII = *TM.getInstrInfo(); - const TargetRegisterInfo &TRI = *TM.getRegisterInfo(); - - - // 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 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.isReg() && MO.getReg()) { - if (TargetRegisterInfo::isVirtualRegister(MO.getReg())) { - unsigned VirtReg = MO.getReg(); - unsigned SubIdx = MO.getSubReg(); - unsigned PhysReg = VRM.getPhys(VirtReg); - unsigned RReg = SubIdx ? TRI.getSubReg(PhysReg, SubIdx) : PhysReg; - if (!VRM.isAssignedReg(VirtReg)) { - int StackSlot = VRM.getStackSlot(VirtReg); - const TargetRegisterClass* RC = - MF.getRegInfo().getRegClass(VirtReg); - - if (MO.isUse() && - std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg) - == LoadedRegs.end()) { - TII.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC); - MachineInstr *LoadMI = prior(MII); - VRM.addSpillSlotUse(StackSlot, LoadMI); - LoadedRegs.push_back(VirtReg); - ++NumLoads; - DOUT << '\t' << *LoadMI; - } - - if (MO.isDef()) { - TII.storeRegToStackSlot(MBB, next(MII), PhysReg, true, - StackSlot, RC); - MachineInstr *StoreMI = next(MII); - VRM.addSpillSlotUse(StackSlot, StoreMI); - ++NumStores; - } - } - MF.getRegInfo().setPhysRegUsed(RReg); - MI.getOperand(i).setReg(RReg); - } else { - MF.getRegInfo().setPhysRegUsed(MO.getReg()); - } - } - } - - DOUT << '\t' << MI; - LoadedRegs.clear(); - } - } - return true; + print(dbgs()); } +#endif //===----------------------------------------------------------------------===// -// Local Spiller Implementation +// VirtRegRewriter //===----------------------------------------------------------------------===// - -namespace { - class AvailableSpills; - - /// LocalSpiller - This spiller does a simple pass over the machine basic - /// block to attempt to keep spills in registers as much as possible for - /// blocks that have low register pressure (the vreg may be spilled due to - /// register pressure in other blocks). - class VISIBILITY_HIDDEN LocalSpiller : public Spiller { - MachineRegisterInfo *RegInfo; - const TargetRegisterInfo *TRI; - const TargetInstrInfo *TII; - DenseMap DistanceMap; - public: - bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) { - RegInfo = &MF.getRegInfo(); - TRI = MF.getTarget().getRegisterInfo(); - TII = MF.getTarget().getInstrInfo(); - DOUT << "\n**** Local spiller rewriting function '" - << MF.getFunction()->getName() << "':\n"; - DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!)" - " ****\n"; - DEBUG(MF.dump()); - - for (MachineFunction::iterator MBB = MF.begin(), E = MF.end(); - MBB != E; ++MBB) - RewriteMBB(*MBB, VRM); - - // Mark unused spill slots. - MachineFrameInfo *MFI = MF.getFrameInfo(); - int SS = VRM.getLowSpillSlot(); - if (SS != VirtRegMap::NO_STACK_SLOT) - for (int e = VRM.getHighSpillSlot(); SS <= e; ++SS) - if (!VRM.isSpillSlotUsed(SS)) { - MFI->RemoveStackObject(SS); - ++NumDSS; - } - - DOUT << "**** Post Machine Instrs ****\n"; - DEBUG(MF.dump()); - - return true; - } - private: - void TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist, - unsigned Reg, BitVector &RegKills, - std::vector &KillOps); - bool PrepForUnfoldOpti(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - std::vector &MaybeDeadStores, - AvailableSpills &Spills, BitVector &RegKills, - std::vector &KillOps, - VirtRegMap &VRM); - bool CommuteToFoldReload(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - unsigned VirtReg, unsigned SrcReg, int SS, - BitVector &RegKills, - std::vector &KillOps, - const TargetRegisterInfo *TRI, - VirtRegMap &VRM); - void SpillRegToStackSlot(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - int Idx, unsigned PhysReg, int StackSlot, - const TargetRegisterClass *RC, - bool isAvailable, MachineInstr *&LastStore, - AvailableSpills &Spills, - SmallSet &ReMatDefs, - BitVector &RegKills, - std::vector &KillOps, - VirtRegMap &VRM); - void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM); - }; -} - -/// AvailableSpills - As the local spiller is scanning and rewriting an MBB from -/// top down, keep track of which spills slots or remat are available in each -/// register. -/// -/// Note that not all physregs are created equal here. In particular, some -/// physregs are reloads that we are allowed to clobber or ignore at any time. -/// Other physregs are values that the register allocated program is using that -/// we cannot CHANGE, but we can read if we like. We keep track of this on a -/// per-stack-slot / remat id basis as the low bit in the value of the -/// SpillSlotsAvailable entries. The predicate 'canClobberPhysReg()' checks -/// this bit and addAvailable sets it if. +// +// The VirtRegRewriter is the last of the register allocator passes. +// It rewrites virtual registers to physical registers as specified in the +// VirtRegMap analysis. It also updates live-in information on basic blocks +// according to LiveIntervals. +// namespace { -class VISIBILITY_HIDDEN AvailableSpills { +class VirtRegRewriter : public MachineFunctionPass { + MachineFunction *MF; + const TargetMachine *TM; const TargetRegisterInfo *TRI; const TargetInstrInfo *TII; - - // SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled - // or remat'ed virtual register values that are still available, due to being - // loaded or stored to, but not invalidated yet. - std::map SpillSlotsOrReMatsAvailable; - - // PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable, - // indicating which stack slot values are currently held by a physreg. This - // is used to invalidate entries in SpillSlotsOrReMatsAvailable when a - // physreg is modified. - std::multimap PhysRegsAvailable; - - void disallowClobberPhysRegOnly(unsigned PhysReg); - - void ClobberPhysRegOnly(unsigned PhysReg); + MachineRegisterInfo *MRI; + SlotIndexes *Indexes; + LiveIntervals *LIS; + VirtRegMap *VRM; + SparseSet PhysRegs; + + void rewrite(); + void addMBBLiveIns(); public: - AvailableSpills(const TargetRegisterInfo *tri, const TargetInstrInfo *tii) - : TRI(tri), TII(tii) { - } - - const TargetRegisterInfo *getRegInfo() const { return TRI; } + static char ID; + VirtRegRewriter() : MachineFunctionPass(ID) {} - /// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is - /// available in a physical register, return that PhysReg, otherwise - /// return 0. - unsigned getSpillSlotOrReMatPhysReg(int Slot) const { - std::map::const_iterator I = - SpillSlotsOrReMatsAvailable.find(Slot); - if (I != SpillSlotsOrReMatsAvailable.end()) { - return I->second >> 1; // Remove the CanClobber bit. - } - return 0; - } + void getAnalysisUsage(AnalysisUsage &AU) const override; - /// addAvailable - Mark that the specified stack slot / remat is available in - /// the specified physreg. If CanClobber is true, the physreg can be modified - /// at any time without changing the semantics of the program. - void addAvailable(int SlotOrReMat, MachineInstr *MI, unsigned Reg, - bool CanClobber = true) { - // If this stack slot is thought to be available in some other physreg, - // remove its record. - ModifyStackSlotOrReMat(SlotOrReMat); - - PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat)); - SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber; - - if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT) - DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1; - else - DOUT << "Remembering SS#" << SlotOrReMat; - DOUT << " in physreg " << TRI->getName(Reg) << "\n"; - } - - /// canClobberPhysReg - Return true if the spiller is allowed to change the - /// value of the specified stackslot register if it desires. The specified - /// stack slot must be available in a physreg for this query to make sense. - bool canClobberPhysReg(int SlotOrReMat) const { - assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) && - "Value not available!"); - return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1; - } - - /// disallowClobberPhysReg - Unset the CanClobber bit of the specified - /// stackslot register. The register is still available but is no longer - /// allowed to be modifed. - void disallowClobberPhysReg(unsigned PhysReg); - - /// ClobberPhysReg - This is called when the specified physreg changes - /// value. We use this to invalidate any info about stuff that lives in - /// it and any of its aliases. - void ClobberPhysReg(unsigned PhysReg); - - /// ModifyStackSlotOrReMat - This method is called when the value in a stack - /// slot changes. This removes information about which register the previous - /// value for this slot lives in (as the previous value is dead now). - void ModifyStackSlotOrReMat(int SlotOrReMat); + bool runOnMachineFunction(MachineFunction&) override; }; +} // end anonymous namespace + +char &llvm::VirtRegRewriterID = VirtRegRewriter::ID; + +INITIALIZE_PASS_BEGIN(VirtRegRewriter, "virtregrewriter", + "Virtual Register Rewriter", false, false) +INITIALIZE_PASS_DEPENDENCY(SlotIndexes) +INITIALIZE_PASS_DEPENDENCY(LiveIntervals) +INITIALIZE_PASS_DEPENDENCY(LiveDebugVariables) +INITIALIZE_PASS_DEPENDENCY(LiveStacks) +INITIALIZE_PASS_DEPENDENCY(VirtRegMap) +INITIALIZE_PASS_END(VirtRegRewriter, "virtregrewriter", + "Virtual Register Rewriter", false, false) + +char VirtRegRewriter::ID = 0; + +void VirtRegRewriter::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesCFG(); + AU.addRequired(); + AU.addRequired(); + AU.addPreserved(); + AU.addRequired(); + AU.addRequired(); + AU.addPreserved(); + AU.addRequired(); + MachineFunctionPass::getAnalysisUsage(AU); +} + +bool VirtRegRewriter::runOnMachineFunction(MachineFunction &fn) { + MF = &fn; + TM = &MF->getTarget(); + TRI = MF->getSubtarget().getRegisterInfo(); + TII = MF->getSubtarget().getInstrInfo(); + MRI = &MF->getRegInfo(); + Indexes = &getAnalysis(); + LIS = &getAnalysis(); + VRM = &getAnalysis(); + DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n" + << "********** Function: " + << MF->getName() << '\n'); + DEBUG(VRM->dump()); + + // Add kill flags while we still have virtual registers. + LIS->addKillFlags(VRM); + + // Live-in lists on basic blocks are required for physregs. + addMBBLiveIns(); + + // Rewrite virtual registers. + rewrite(); + + // Write out new DBG_VALUE instructions. + getAnalysis().emitDebugValues(VRM); + + // All machine operands and other references to virtual registers have been + // replaced. Remove the virtual registers and release all the transient data. + VRM->clearAllVirt(); + MRI->clearVirtRegs(); + return true; } -/// 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::iterator I = - PhysRegsAvailable.lower_bound(PhysReg); - while (I != PhysRegsAvailable.end() && I->first == PhysReg) { - int SlotOrReMat = I->second; - I++; - assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg && - "Bidirectional map mismatch!"); - SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1; - DOUT << "PhysReg " << TRI->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 = TRI->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::iterator I = - PhysRegsAvailable.lower_bound(PhysReg); - while (I != PhysRegsAvailable.end() && I->first == PhysReg) { - int SlotOrReMat = I->second; - PhysRegsAvailable.erase(I++); - assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg && - "Bidirectional map mismatch!"); - SpillSlotsOrReMatsAvailable.erase(SlotOrReMat); - DOUT << "PhysReg " << TRI->getName(PhysReg) - << " clobbered, invalidating "; - if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT) - DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n"; - else - DOUT << "SS#" << SlotOrReMat << "\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 = TRI->getAliasSet(PhysReg); *AS; ++AS) - ClobberPhysRegOnly(*AS); - ClobberPhysRegOnly(PhysReg); -} - -/// ModifyStackSlotOrReMat - This method is called when the value in a stack -/// slot changes. This removes information about which register the previous -/// value for this slot lives in (as the previous value is dead now). -void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) { - std::map::iterator It = - SpillSlotsOrReMatsAvailable.find(SlotOrReMat); - if (It == SpillSlotsOrReMatsAvailable.end()) return; - unsigned Reg = It->second >> 1; - SpillSlotsOrReMatsAvailable.erase(It); - - // This register may hold the value of multiple stack slots, only remove this - // stack slot from the set of values the register contains. - std::multimap::iterator I = PhysRegsAvailable.lower_bound(Reg); - for (; ; ++I) { - assert(I != PhysRegsAvailable.end() && I->first == Reg && - "Map inverse broken!"); - if (I->second == SlotOrReMat) break; - } - PhysRegsAvailable.erase(I); -} - - - -/// InvalidateKills - MI is going to be deleted. If any of its operands are -/// marked kill, then invalidate the information. -static void InvalidateKills(MachineInstr &MI, BitVector &RegKills, - std::vector &KillOps, - SmallVector *KillRegs = NULL) { - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI.getOperand(i); - if (!MO.isReg() || !MO.isUse() || !MO.isKill()) - continue; - unsigned Reg = MO.getReg(); - if (TargetRegisterInfo::isVirtualRegister(Reg)) - continue; - if (KillRegs) - KillRegs->push_back(Reg); - assert(Reg < KillOps.size()); - if (KillOps[Reg] == &MO) { - RegKills.reset(Reg); - KillOps[Reg] = NULL; - } - } -} - -/// InvalidateKill - A MI that defines the specified register is being deleted, -/// invalidate the register kill information. -static void InvalidateKill(unsigned Reg, BitVector &RegKills, - std::vector &KillOps) { - if (RegKills[Reg]) { - KillOps[Reg]->setIsKill(false); - KillOps[Reg] = NULL; - RegKills.reset(Reg); - } -} - -/// InvalidateRegDef - If the def operand of the specified def MI is now dead -/// (since it's spill instruction is removed), mark it isDead. Also checks if -/// the def MI has other definition operands that are not dead. Returns it by -/// reference. -static bool InvalidateRegDef(MachineBasicBlock::iterator I, - MachineInstr &NewDef, unsigned Reg, - bool &HasLiveDef) { - // Due to remat, it's possible this reg isn't being reused. That is, - // the def of this reg (by prev MI) is now dead. - MachineInstr *DefMI = I; - MachineOperand *DefOp = NULL; - for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = DefMI->getOperand(i); - if (MO.isReg() && MO.isDef()) { - if (MO.getReg() == Reg) - DefOp = &MO; - else if (!MO.isDead()) - HasLiveDef = true; - } - } - if (!DefOp) - return false; - - bool FoundUse = false, Done = false; - MachineBasicBlock::iterator E = &NewDef; - ++I; ++E; - for (; !Done && I != E; ++I) { - MachineInstr *NMI = I; - for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) { - MachineOperand &MO = NMI->getOperand(j); - if (!MO.isReg() || MO.getReg() != Reg) - continue; - if (MO.isUse()) - FoundUse = true; - Done = true; // Stop after scanning all the operands of this MI. - } - } - if (!FoundUse) { - // Def is dead! - DefOp->setIsDead(); - return true; - } - return false; -} - -/// UpdateKills - Track and update kill info. If a MI reads a register that is -/// marked kill, then it must be due to register reuse. Transfer the kill info -/// over. -static void UpdateKills(MachineInstr &MI, BitVector &RegKills, - std::vector &KillOps, - const TargetRegisterInfo* TRI) { - const TargetInstrDesc &TID = MI.getDesc(); - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI.getOperand(i); - if (!MO.isReg() || !MO.isUse()) - continue; - unsigned Reg = MO.getReg(); - if (Reg == 0) - continue; - - if (RegKills[Reg] && KillOps[Reg]->getParent() != &MI) { - // That can't be right. Register is killed but not re-defined and it's - // being reused. Let's fix that. - KillOps[Reg]->setIsKill(false); - KillOps[Reg] = NULL; - RegKills.reset(Reg); - if (i < TID.getNumOperands() && - TID.getOperandConstraint(i, TOI::TIED_TO) == -1) - // Unless it's a two-address operand, this is the new kill. - MO.setIsKill(); - } - if (MO.isKill()) { - RegKills.set(Reg); - KillOps[Reg] = &MO; - } - } - - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - const MachineOperand &MO = MI.getOperand(i); - if (!MO.isReg() || !MO.isDef()) - continue; - unsigned Reg = MO.getReg(); - RegKills.reset(Reg); - KillOps[Reg] = NULL; - // It also defines (or partially define) aliases. - for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS) { - RegKills.reset(*AS); - KillOps[*AS] = NULL; - } - } -} - -/// ReMaterialize - Re-materialize definition for Reg targetting DestReg. -/// -static void ReMaterialize(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - unsigned DestReg, unsigned Reg, - const TargetInstrInfo *TII, - const TargetRegisterInfo *TRI, - VirtRegMap &VRM) { - TII->reMaterialize(MBB, MII, DestReg, VRM.getReMaterializedMI(Reg)); - MachineInstr *NewMI = prior(MII); - for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = NewMI->getOperand(i); - if (!MO.isReg() || MO.getReg() == 0) +// Compute MBB live-in lists from virtual register live ranges and their +// assignments. +void VirtRegRewriter::addMBBLiveIns() { + SmallVector LiveIn; + for (unsigned Idx = 0, IdxE = MRI->getNumVirtRegs(); Idx != IdxE; ++Idx) { + unsigned VirtReg = TargetRegisterInfo::index2VirtReg(Idx); + if (MRI->reg_nodbg_empty(VirtReg)) continue; - unsigned VirtReg = MO.getReg(); - if (TargetRegisterInfo::isPhysicalRegister(VirtReg)) + LiveInterval &LI = LIS->getInterval(VirtReg); + if (LI.empty() || LIS->intervalIsInOneMBB(LI)) continue; - assert(MO.isUse()); - unsigned SubIdx = MO.getSubReg(); - unsigned Phys = VRM.getPhys(VirtReg); - assert(Phys); - unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys; - MO.setReg(RReg); - } - ++NumReMats; -} - - -// 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; - - // StackSlotOrReMat - The spill slot or remat id of the value being reused. - unsigned StackSlotOrReMat; - - // PhysRegReused - The physical register the value was available in. - unsigned PhysRegReused; - - // 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), StackSlotOrReMat(ss), PhysRegReused(prr), - AssignedPhysReg(apr), VirtReg(vreg) {} - }; - - /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that - /// is reused instead of reloaded. - class VISIBILITY_HIDDEN ReuseInfo { - MachineInstr &MI; - std::vector Reuses; - BitVector PhysRegsClobbered; - public: - ReuseInfo(MachineInstr &mi, const TargetRegisterInfo *tri) : MI(mi) { - PhysRegsClobbered.resize(tri->getNumRegs()); - } - - bool hasReuses() const { - return !Reuses.empty(); - } - - /// addReuse - If we choose to reuse a virtual register that is already - /// available instead of reloading it, remember that we did so. - void addReuse(unsigned OpNo, unsigned StackSlotOrReMat, - unsigned PhysRegReused, unsigned AssignedPhysReg, - unsigned VirtReg) { - // If the reload is to the assigned register anyway, no undo will be - // required. - if (PhysRegReused == AssignedPhysReg) return; - - // Otherwise, remember this. - Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused, - AssignedPhysReg, VirtReg)); - } - - void markClobbered(unsigned PhysReg) { - PhysRegsClobbered.set(PhysReg); - } - - bool isClobbered(unsigned PhysReg) const { - return PhysRegsClobbered.test(PhysReg); - } - - /// GetRegForReload - We are about to emit a reload into PhysReg. If there - /// is some other operand that is using the specified register, either pick - /// a new register to use, or evict the previous reload and use this reg. - unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI, - AvailableSpills &Spills, - std::vector &MaybeDeadStores, - SmallSet &Rejected, - BitVector &RegKills, - std::vector &KillOps, - VirtRegMap &VRM) { - const TargetInstrInfo* TII = MI->getParent()->getParent()->getTarget() - .getInstrInfo(); - - if (Reuses.empty()) return PhysReg; // This is most often empty. - - for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) { - ReusedOp &Op = Reuses[ro]; - // If we find some other reuse that was supposed to use this register - // exactly for its reload, we can change this reload to use ITS reload - // register. That is, unless its reload register has already been - // considered and subsequently rejected because it has also been reused - // by another operand. - if (Op.PhysRegReused == PhysReg && - Rejected.count(Op.AssignedPhysReg) == 0) { - // Yup, use the reload register that we didn't use before. - unsigned NewReg = Op.AssignedPhysReg; - Rejected.insert(PhysReg); - return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected, - RegKills, KillOps, VRM); - } else { - // Otherwise, we might also have a problem if a previously reused - // value aliases the new register. If so, codegen the previous reload - // and use this one. - unsigned PRRU = Op.PhysRegReused; - const TargetRegisterInfo *TRI = Spills.getRegInfo(); - if (TRI->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()->getRegInfo().getRegClass(Op.VirtReg); - - // Copy Op out of the vector and remove it, we're going to insert an - // explicit load for it. - ReusedOp NewOp = Op; - Reuses.erase(Reuses.begin()+ro); - - // Ok, we're going to try to reload the assigned physreg into the - // slot that we were supposed to in the first place. However, that - // register could hold a reuse. Check to see if it conflicts or - // would prefer us to use a different register. - unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg, - MI, Spills, MaybeDeadStores, - Rejected, RegKills, KillOps, VRM); - - MachineBasicBlock::iterator MII = MI; - if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) { - ReMaterialize(*MBB, MII, NewPhysReg, NewOp.VirtReg, TII, TRI,VRM); - } else { - TII->loadRegFromStackSlot(*MBB, MII, NewPhysReg, - NewOp.StackSlotOrReMat, AliasRC); - MachineInstr *LoadMI = prior(MII); - VRM.addSpillSlotUse(NewOp.StackSlotOrReMat, LoadMI); - // Any stores to this stack slot are not dead anymore. - MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL; - ++NumLoads; + // This is a virtual register that is live across basic blocks. Its + // assigned PhysReg must be marked as live-in to those blocks. + unsigned PhysReg = VRM->getPhys(VirtReg); + assert(PhysReg != VirtRegMap::NO_PHYS_REG && "Unmapped virtual register."); + + if (LI.hasSubRanges()) { + for (LiveInterval::SubRange &S : LI.subranges()) { + for (const auto &Seg : S.segments) { + if (!Indexes->findLiveInMBBs(Seg.start, Seg.end, LiveIn)) + continue; + for (MCSubRegIndexIterator SR(PhysReg, TRI); SR.isValid(); ++SR) { + unsigned SubReg = SR.getSubReg(); + unsigned SubRegIndex = SR.getSubRegIndex(); + unsigned SubRegLaneMask = TRI->getSubRegIndexLaneMask(SubRegIndex); + if ((SubRegLaneMask & S.LaneMask) == 0) + continue; + for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) { + if (!LiveIn[i]->isLiveIn(SubReg)) + LiveIn[i]->addLiveIn(SubReg); } - Spills.ClobberPhysReg(NewPhysReg); - Spills.ClobberPhysReg(NewOp.PhysRegReused); - - unsigned SubIdx = MI->getOperand(NewOp.Operand).getSubReg(); - unsigned RReg = SubIdx ? TRI->getSubReg(NewPhysReg, SubIdx) : NewPhysReg; - MI->getOperand(NewOp.Operand).setReg(RReg); - - Spills.addAvailable(NewOp.StackSlotOrReMat, MI, NewPhysReg); - --MII; - UpdateKills(*MII, RegKills, KillOps, TRI); - DOUT << '\t' << *MII; - - DOUT << "Reuse undone!\n"; - --NumReused; - - // Finally, PhysReg is now available, go ahead and use it. - return PhysReg; } + LiveIn.clear(); } } - 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::vector &MaybeDeadStores, - BitVector &RegKills, - std::vector &KillOps, - VirtRegMap &VRM) { - SmallSet Rejected; - return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected, - RegKills, KillOps, VRM); - } - }; -} - -/// PrepForUnfoldOpti - Turn a store folding instruction into a load folding -/// instruction. e.g. -/// xorl %edi, %eax -/// movl %eax, -32(%ebp) -/// movl -36(%ebp), %eax -/// orl %eax, -32(%ebp) -/// ==> -/// xorl %edi, %eax -/// orl -36(%ebp), %eax -/// mov %eax, -32(%ebp) -/// This enables unfolding optimization for a subsequent instruction which will -/// also eliminate the newly introduced store instruction. -bool LocalSpiller::PrepForUnfoldOpti(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - std::vector &MaybeDeadStores, - AvailableSpills &Spills, - BitVector &RegKills, - std::vector &KillOps, - VirtRegMap &VRM) { - MachineFunction &MF = *MBB.getParent(); - MachineInstr &MI = *MII; - unsigned UnfoldedOpc = 0; - unsigned UnfoldPR = 0; - unsigned UnfoldVR = 0; - int FoldedSS = VirtRegMap::NO_STACK_SLOT; - VirtRegMap::MI2VirtMapTy::const_iterator I, End; - for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) { - // Only transform a MI that folds a single register. - if (UnfoldedOpc) - return false; - UnfoldVR = I->second.first; - VirtRegMap::ModRef MR = I->second.second; - // MI2VirtMap be can updated which invalidate the iterator. - // Increment the iterator first. - ++I; - if (VRM.isAssignedReg(UnfoldVR)) - continue; - // If this reference is not a use, any previous store is now dead. - // Otherwise, the store to this stack slot is not dead anymore. - FoldedSS = VRM.getStackSlot(UnfoldVR); - MachineInstr* DeadStore = MaybeDeadStores[FoldedSS]; - if (DeadStore && (MR & VirtRegMap::isModRef)) { - unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(FoldedSS); - if (!PhysReg || !DeadStore->readsRegister(PhysReg)) - continue; - UnfoldPR = PhysReg; - UnfoldedOpc = TII->getOpcodeAfterMemoryUnfold(MI.getOpcode(), - false, true); - } - } - - if (!UnfoldedOpc) - return false; - - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI.getOperand(i); - if (!MO.isReg() || MO.getReg() == 0 || !MO.isUse()) - continue; - unsigned VirtReg = MO.getReg(); - if (TargetRegisterInfo::isPhysicalRegister(VirtReg) || MO.getSubReg()) - continue; - if (VRM.isAssignedReg(VirtReg)) { - unsigned PhysReg = VRM.getPhys(VirtReg); - if (PhysReg && TRI->regsOverlap(PhysReg, UnfoldPR)) - return false; - } else if (VRM.isReMaterialized(VirtReg)) - continue; - int SS = VRM.getStackSlot(VirtReg); - unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS); - if (PhysReg) { - if (TRI->regsOverlap(PhysReg, UnfoldPR)) - return false; - continue; - } - if (VRM.hasPhys(VirtReg)) { - PhysReg = VRM.getPhys(VirtReg); - if (!TRI->regsOverlap(PhysReg, UnfoldPR)) - continue; - } - - // Ok, we'll need to reload the value into a register which makes - // it impossible to perform the store unfolding optimization later. - // Let's see if it is possible to fold the load if the store is - // unfolded. This allows us to perform the store unfolding - // optimization. - SmallVector NewMIs; - if (TII->unfoldMemoryOperand(MF, &MI, UnfoldVR, false, false, NewMIs)) { - assert(NewMIs.size() == 1); - MachineInstr *NewMI = NewMIs.back(); - NewMIs.clear(); - int Idx = NewMI->findRegisterUseOperandIdx(VirtReg, false); - assert(Idx != -1); - SmallVector Ops; - Ops.push_back(Idx); - MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, NewMI, Ops, SS); - if (FoldedMI) { - VRM.addSpillSlotUse(SS, FoldedMI); - if (!VRM.hasPhys(UnfoldVR)) - VRM.assignVirt2Phys(UnfoldVR, UnfoldPR); - VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef); - MII = MBB.insert(MII, FoldedMI); - InvalidateKills(MI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - MF.DeleteMachineInstr(NewMI); - return true; - } - MF.DeleteMachineInstr(NewMI); - } - } - return false; -} - -/// CommuteToFoldReload - -/// Look for -/// r1 = load fi#1 -/// r1 = op r1, r2 -/// store r1, fi#1 -/// -/// If op is commutable and r2 is killed, then we can xform these to -/// r2 = op r2, fi#1 -/// store r2, fi#1 -bool LocalSpiller::CommuteToFoldReload(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - unsigned VirtReg, unsigned SrcReg, int SS, - BitVector &RegKills, - std::vector &KillOps, - const TargetRegisterInfo *TRI, - VirtRegMap &VRM) { - if (MII == MBB.begin() || !MII->killsRegister(SrcReg)) - return false; - - MachineFunction &MF = *MBB.getParent(); - MachineInstr &MI = *MII; - MachineBasicBlock::iterator DefMII = prior(MII); - MachineInstr *DefMI = DefMII; - const TargetInstrDesc &TID = DefMI->getDesc(); - unsigned NewDstIdx; - if (DefMII != MBB.begin() && - TID.isCommutable() && - TII->CommuteChangesDestination(DefMI, NewDstIdx)) { - MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx); - unsigned NewReg = NewDstMO.getReg(); - if (!NewDstMO.isKill() || TRI->regsOverlap(NewReg, SrcReg)) - return false; - MachineInstr *ReloadMI = prior(DefMII); - int FrameIdx; - unsigned DestReg = TII->isLoadFromStackSlot(ReloadMI, FrameIdx); - if (DestReg != SrcReg || FrameIdx != SS) - return false; - int UseIdx = DefMI->findRegisterUseOperandIdx(DestReg, false); - if (UseIdx == -1) - return false; - int DefIdx = TID.getOperandConstraint(UseIdx, TOI::TIED_TO); - if (DefIdx == -1) - return false; - assert(DefMI->getOperand(DefIdx).isReg() && - DefMI->getOperand(DefIdx).getReg() == SrcReg); - - // Now commute def instruction. - MachineInstr *CommutedMI = TII->commuteInstruction(DefMI, true); - if (!CommutedMI) - return false; - SmallVector Ops; - Ops.push_back(NewDstIdx); - MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, CommutedMI, Ops, SS); - // Not needed since foldMemoryOperand returns new MI. - MF.DeleteMachineInstr(CommutedMI); - if (!FoldedMI) - return false; - - VRM.addSpillSlotUse(SS, FoldedMI); - VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef); - // Insert new def MI and spill MI. - const TargetRegisterClass* RC = MF.getRegInfo().getRegClass(VirtReg); - TII->storeRegToStackSlot(MBB, &MI, NewReg, true, SS, RC); - MII = prior(MII); - MachineInstr *StoreMI = MII; - VRM.addSpillSlotUse(SS, StoreMI); - VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod); - MII = MBB.insert(MII, FoldedMI); // Update MII to backtrack. - - // Delete all 3 old instructions. - InvalidateKills(*ReloadMI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(ReloadMI); - MBB.erase(ReloadMI); - InvalidateKills(*DefMI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(DefMI); - MBB.erase(DefMI); - InvalidateKills(MI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - - ++NumCommutes; - return true; - } - - return false; -} - -/// findSuperReg - Find the SubReg's super-register of given register class -/// where its SubIdx sub-register is SubReg. -static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg, - unsigned SubIdx, const TargetRegisterInfo *TRI) { - for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end(); - I != E; ++I) { - unsigned Reg = *I; - if (TRI->getSubReg(Reg, SubIdx) == SubReg) - return Reg; - } - return 0; -} - -/// SpillRegToStackSlot - Spill a register to a specified stack slot. Check if -/// the last store to the same slot is now dead. If so, remove the last store. -void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB, - MachineBasicBlock::iterator &MII, - int Idx, unsigned PhysReg, int StackSlot, - const TargetRegisterClass *RC, - bool isAvailable, MachineInstr *&LastStore, - AvailableSpills &Spills, - SmallSet &ReMatDefs, - BitVector &RegKills, - std::vector &KillOps, - VirtRegMap &VRM) { - TII->storeRegToStackSlot(MBB, next(MII), PhysReg, true, StackSlot, RC); - MachineInstr *StoreMI = next(MII); - VRM.addSpillSlotUse(StackSlot, StoreMI); - DOUT << "Store:\t" << *StoreMI; - - // If there is a dead store to this stack slot, nuke it now. - if (LastStore) { - DOUT << "Removed dead store:\t" << *LastStore; - ++NumDSE; - SmallVector KillRegs; - InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs); - MachineBasicBlock::iterator PrevMII = LastStore; - bool CheckDef = PrevMII != MBB.begin(); - if (CheckDef) - --PrevMII; - VRM.RemoveMachineInstrFromMaps(LastStore); - MBB.erase(LastStore); - if (CheckDef) { - // Look at defs of killed registers on the store. Mark the defs - // as dead since the store has been deleted and they aren't - // being reused. - for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) { - bool HasOtherDef = false; - if (InvalidateRegDef(PrevMII, *MII, KillRegs[j], HasOtherDef)) { - MachineInstr *DeadDef = PrevMII; - if (ReMatDefs.count(DeadDef) && !HasOtherDef) { - // FIXME: This assumes a remat def does not have side - // effects. - VRM.RemoveMachineInstrFromMaps(DeadDef); - MBB.erase(DeadDef); - ++NumDRM; - } - } + } else { + // Scan the segments of LI. + for (const auto &Seg : LI.segments) { + if (!Indexes->findLiveInMBBs(Seg.start, Seg.end, LiveIn)) + continue; + for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) + if (!LiveIn[i]->isLiveIn(PhysReg)) + LiveIn[i]->addLiveIn(PhysReg); + LiveIn.clear(); } } } - - LastStore = next(MII); - - // If the stack slot value was previously available in some other - // register, change it now. Otherwise, make the register available, - // in PhysReg. - Spills.ModifyStackSlotOrReMat(StackSlot); - Spills.ClobberPhysReg(PhysReg); - Spills.addAvailable(StackSlot, LastStore, PhysReg, isAvailable); - ++NumStores; } -/// TransferDeadness - A identity copy definition is dead and it's being -/// removed. Find the last def or use and mark it as dead / kill. -void LocalSpiller::TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist, - unsigned Reg, BitVector &RegKills, - std::vector &KillOps) { - int LastUDDist = -1; - MachineInstr *LastUDMI = NULL; - for (MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(Reg), - RE = RegInfo->reg_end(); RI != RE; ++RI) { - MachineInstr *UDMI = &*RI; - if (UDMI->getParent() != MBB) - continue; - DenseMap::iterator DI = DistanceMap.find(UDMI); - if (DI == DistanceMap.end() || DI->second > CurDist) - continue; - if ((int)DI->second < LastUDDist) - continue; - LastUDDist = DI->second; - LastUDMI = UDMI; - } - - if (LastUDMI) { - const TargetInstrDesc &TID = LastUDMI->getDesc(); - MachineOperand *LastUD = NULL; - for (unsigned i = 0, e = LastUDMI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = LastUDMI->getOperand(i); - if (!MO.isReg() || MO.getReg() != Reg) - continue; - if (!LastUD || (LastUD->isUse() && MO.isDef())) - LastUD = &MO; - if (TID.getOperandConstraint(i, TOI::TIED_TO) != -1) - return; - } - if (LastUD->isDef()) - LastUD->setIsDead(); - else { - LastUD->setIsKill(); - RegKills.set(Reg); - KillOps[Reg] = LastUD; - } - } -} - -/// rewriteMBB - Keep track of which spills are available even after the -/// register allocator is done with them. If possible, avid reloading vregs. -void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) { - DOUT << MBB.getBasicBlock()->getName() << ":\n"; - - MachineFunction &MF = *MBB.getParent(); - - // Spills - Keep track of which spilled values are available in physregs so - // that we can choose to reuse the physregs instead of emitting reloads. - AvailableSpills Spills(TRI, 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::vector MaybeDeadStores; - MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL); - - // ReMatDefs - These are rematerializable def MIs which are not deleted. - SmallSet ReMatDefs; - - // Keep track of kill information. - BitVector RegKills(TRI->getNumRegs()); - std::vector KillOps; - KillOps.resize(TRI->getNumRegs(), NULL); - - unsigned Dist = 0; - DistanceMap.clear(); - for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end(); - MII != E; ) { - MachineBasicBlock::iterator NextMII = MII; ++NextMII; - - VirtRegMap::MI2VirtMapTy::const_iterator I, End; - bool Erased = false; - bool BackTracked = false; - if (PrepForUnfoldOpti(MBB, MII, - MaybeDeadStores, Spills, RegKills, KillOps, VRM)) - NextMII = next(MII); - - MachineInstr &MI = *MII; - const TargetInstrDesc &TID = MI.getDesc(); - - if (VRM.hasEmergencySpills(&MI)) { - // Spill physical register(s) in the rare case the allocator has run out - // of registers to allocate. - SmallSet UsedSS; - std::vector &EmSpills = VRM.getEmergencySpills(&MI); - for (unsigned i = 0, e = EmSpills.size(); i != e; ++i) { - unsigned PhysReg = EmSpills[i]; - const TargetRegisterClass *RC = - TRI->getPhysicalRegisterRegClass(PhysReg); - assert(RC && "Unable to determine register class!"); - int SS = VRM.getEmergencySpillSlot(RC); - if (UsedSS.count(SS)) - assert(0 && "Need to spill more than one physical registers!"); - UsedSS.insert(SS); - TII->storeRegToStackSlot(MBB, MII, PhysReg, true, SS, RC); - MachineInstr *StoreMI = prior(MII); - VRM.addSpillSlotUse(SS, StoreMI); - TII->loadRegFromStackSlot(MBB, next(MII), PhysReg, SS, RC); - MachineInstr *LoadMI = next(MII); - VRM.addSpillSlotUse(SS, LoadMI); - ++NumPSpills; - } - NextMII = next(MII); - } - - // Insert restores here if asked to. - if (VRM.isRestorePt(&MI)) { - std::vector &RestoreRegs = VRM.getRestorePtRestores(&MI); - for (unsigned i = 0, e = RestoreRegs.size(); i != e; ++i) { - unsigned VirtReg = RestoreRegs[e-i-1]; // Reverse order. - if (!VRM.getPreSplitReg(VirtReg)) - continue; // Split interval spilled again. - unsigned Phys = VRM.getPhys(VirtReg); - RegInfo->setPhysRegUsed(Phys); - if (VRM.isReMaterialized(VirtReg)) { - ReMaterialize(MBB, MII, Phys, VirtReg, TII, TRI, VRM); - } else { - const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg); - int SS = VRM.getStackSlot(VirtReg); - TII->loadRegFromStackSlot(MBB, &MI, Phys, SS, RC); - MachineInstr *LoadMI = prior(MII); - VRM.addSpillSlotUse(SS, LoadMI); - ++NumLoads; +void VirtRegRewriter::rewrite() { + bool NoSubRegLiveness = !MRI->tracksSubRegLiveness(); + SmallVector SuperDeads; + SmallVector SuperDefs; + SmallVector SuperKills; + SmallPtrSet NoReturnInsts; + + // Here we have a SparseSet to hold which PhysRegs are actually encountered + // in the MF we are about to iterate over so that later when we call + // setPhysRegUsed, we are only doing it for physRegs that were actually found + // in the program and not for all of the possible physRegs for the given + // target architecture. If the target has a lot of physRegs, then for a small + // program there will be a significant compile time reduction here. + PhysRegs.clear(); + PhysRegs.setUniverse(TRI->getNumRegs()); + + // The function with uwtable should guarantee that the stack unwinder + // can unwind the stack to the previous frame. Thus, we can't apply the + // noreturn optimization if the caller function has uwtable attribute. + bool HasUWTable = MF->getFunction()->hasFnAttribute(Attribute::UWTable); + + for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end(); + MBBI != MBBE; ++MBBI) { + DEBUG(MBBI->print(dbgs(), Indexes)); + bool IsExitBB = MBBI->succ_empty(); + for (MachineBasicBlock::instr_iterator + MII = MBBI->instr_begin(), MIE = MBBI->instr_end(); MII != MIE;) { + MachineInstr *MI = MII; + ++MII; + + // Check if this instruction is a call to a noreturn function. If this + // is a call to noreturn function and we don't need the stack unwinding + // functionality (i.e. this function does not have uwtable attribute and + // the callee function has the nounwind attribute), then we can ignore + // the definitions set by this instruction. + if (!HasUWTable && IsExitBB && MI->isCall()) { + for (MachineInstr::mop_iterator MOI = MI->operands_begin(), + MOE = MI->operands_end(); MOI != MOE; ++MOI) { + MachineOperand &MO = *MOI; + if (!MO.isGlobal()) + continue; + const Function *Func = dyn_cast(MO.getGlobal()); + if (!Func || !Func->hasFnAttribute(Attribute::NoReturn) || + // We need to keep correct unwind information + // even if the function will not return, since the + // runtime may need it. + !Func->hasFnAttribute(Attribute::NoUnwind)) + continue; + NoReturnInsts.insert(MI); + break; } - // This invalidates Phys. - Spills.ClobberPhysReg(Phys); - UpdateKills(*prior(MII), RegKills, KillOps, TRI); - DOUT << '\t' << *prior(MII); - } - } - - // Insert spills here if asked to. - if (VRM.isSpillPt(&MI)) { - std::vector > &SpillRegs = - VRM.getSpillPtSpills(&MI); - for (unsigned i = 0, e = SpillRegs.size(); i != e; ++i) { - unsigned VirtReg = SpillRegs[i].first; - bool isKill = SpillRegs[i].second; - if (!VRM.getPreSplitReg(VirtReg)) - continue; // Split interval spilled again. - const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg); - unsigned Phys = VRM.getPhys(VirtReg); - int StackSlot = VRM.getStackSlot(VirtReg); - TII->storeRegToStackSlot(MBB, next(MII), Phys, isKill, StackSlot, RC); - MachineInstr *StoreMI = next(MII); - VRM.addSpillSlotUse(StackSlot, StoreMI); - DOUT << "Store:\t" << *StoreMI; - VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod); - } - NextMII = next(MII); - } - - /// ReusedOperands - Keep track of operand reuse in case we need to undo - /// reuse. - ReuseInfo ReusedOperands(MI, TRI); - SmallVector VirtUseOps; - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI.getOperand(i); - if (!MO.isReg() || MO.getReg() == 0) - continue; // Ignore non-register operands. - - unsigned VirtReg = MO.getReg(); - if (TargetRegisterInfo::isPhysicalRegister(VirtReg)) { - // Ignore physregs for spilling, but remember that it is used by this - // function. - RegInfo->setPhysRegUsed(VirtReg); - continue; - } - - // We want to process implicit virtual register uses first. - if (MO.isImplicit()) - // If the virtual register is implicitly defined, emit a implicit_def - // before so scavenger knows it's "defined". - VirtUseOps.insert(VirtUseOps.begin(), i); - else - VirtUseOps.push_back(i); - } - - // Process all of the spilled uses and all non spilled reg references. - SmallVector PotentialDeadStoreSlots; - for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) { - unsigned i = VirtUseOps[j]; - MachineOperand &MO = MI.getOperand(i); - unsigned VirtReg = MO.getReg(); - assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && - "Not a virtual register?"); - - unsigned SubIdx = MO.getSubReg(); - if (VRM.isAssignedReg(VirtReg)) { - // This virtual register was assigned a physreg! - unsigned Phys = VRM.getPhys(VirtReg); - RegInfo->setPhysRegUsed(Phys); - if (MO.isDef()) - ReusedOperands.markClobbered(Phys); - unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys; - MI.getOperand(i).setReg(RReg); - if (VRM.isImplicitlyDefined(VirtReg)) - BuildMI(MBB, &MI, MI.getDebugLoc(), - TII->get(TargetInstrInfo::IMPLICIT_DEF), RReg); - 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) - bool DoReMat = VRM.isReMaterialized(VirtReg); - int SSorRMId = DoReMat - ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg); - int ReuseSlot = SSorRMId; + for (MachineInstr::mop_iterator MOI = MI->operands_begin(), + MOE = MI->operands_end(); MOI != MOE; ++MOI) { + MachineOperand &MO = *MOI; - // Check to see if this stack slot is available. - unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId); + // Make sure MRI knows about registers clobbered by regmasks. + if (MO.isRegMask()) + MRI->addPhysRegsUsedFromRegMask(MO.getRegMask()); - // If this is a sub-register use, make sure the reuse register is in the - // right register class. For example, for x86 not all of the 32-bit - // registers have accessible sub-registers. - // Similarly so for EXTRACT_SUBREG. Consider this: - // EDI = op - // MOV32_mr fi#1, EDI - // ... - // = EXTRACT_SUBREG fi#1 - // fi#1 is available in EDI, but it cannot be reused because it's not in - // the right register file. - if (PhysReg && - (SubIdx || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) { - const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg); - if (!RC->contains(PhysReg)) - PhysReg = 0; - } - - if (PhysReg) { - // This spilled operand might be part of a two-address operand. If this - // is the case, then changing it will necessarily require changing the - // def part of the instruction as well. However, in some cases, we - // aren't allowed to modify the reused register. If none of these cases - // apply, reuse it. - bool CanReuse = true; - int ti = TID.getOperandConstraint(i, TOI::TIED_TO); - if (ti != -1 && - MI.getOperand(ti).isReg() && - MI.getOperand(ti).getReg() == VirtReg) { - // Okay, we have a two address operand. We can reuse this physreg as - // long as we are allowed to clobber the value and there isn't an - // earlier def that has already clobbered the physreg. - CanReuse = Spills.canClobberPhysReg(ReuseSlot) && - !ReusedOperands.isClobbered(PhysReg); - } - - if (CanReuse) { - // If this stack slot value is already available, reuse it! - if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT) - DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1; - else - DOUT << "Reusing SS#" << ReuseSlot; - DOUT << " from physreg " - << TRI->getName(PhysReg) << " for vreg" - << VirtReg <<" instead of reloading into physreg " - << TRI->getName(VRM.getPhys(VirtReg)) << "\n"; - unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg; - MI.getOperand(i).setReg(RReg); + // If we encounter a VirtReg or PhysReg then get at the PhysReg and add + // it to the physreg bitset. Later we use only the PhysRegs that were + // actually encountered in the MF to populate the MRI's used physregs. + if (MO.isReg() && MO.getReg()) + PhysRegs.insert( + TargetRegisterInfo::isVirtualRegister(MO.getReg()) ? + VRM->getPhys(MO.getReg()) : + MO.getReg()); - // The only technical detail we have is that we don't know that - // PhysReg won't be clobbered by a reloaded stack slot that occurs - // later in the instruction. In particular, consider 'op V1, V2'. - // If V1 is available in physreg R0, we would choose to reuse it - // here, instead of reloading it into the register the allocator - // indicated (say R1). However, V2 might have to be reloaded - // later, and it might indicate that it needs to live in R0. When - // this occurs, we need to have information available that - // indicates it is safe to use R1 for the reload instead of R0. - // - // To further complicate matters, we might conflict with an alias, - // or R0 and R1 might not be compatible with each other. In this - // case, we actually insert a reload for V1 in R1, ensuring that - // we can get at R0 or its alias. - ReusedOperands.addReuse(i, ReuseSlot, PhysReg, - VRM.getPhys(VirtReg), VirtReg); - if (ti != -1) - // Only mark it clobbered if this is a use&def operand. - ReusedOperands.markClobbered(PhysReg); - ++NumReused; - - if (MI.getOperand(i).isKill() && - ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) { - - // The store of this spilled value is potentially dead, but we - // won't know for certain until we've confirmed that the re-use - // above is valid, which means waiting until the other operands - // are processed. For now we just track the spill slot, we'll - // remove it after the other operands are processed if valid. - - PotentialDeadStoreSlots.push_back(ReuseSlot); - } - continue; - } // CanReuse - - // Otherwise we have a situation where we have a two-address instruction - // whose mod/ref operand needs to be reloaded. This reload is already - // available in some register "PhysReg", but if we used PhysReg as the - // operand to our 2-addr instruction, the instruction would modify - // PhysReg. This isn't cool if something later uses PhysReg and expects - // to get its initial value. - // - // To avoid this problem, and to avoid doing a load right after a store, - // we emit a copy from PhysReg into the designated register for this - // operand. - unsigned DesignatedReg = VRM.getPhys(VirtReg); - assert(DesignatedReg && "Must map virtreg to physreg!"); - - // Note that, if we reused a register for a previous operand, the - // register we want to reload into might not actually be - // available. If this occurs, use the register indicated by the - // reuser. - if (ReusedOperands.hasReuses()) - DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI, - Spills, MaybeDeadStores, RegKills, KillOps, VRM); - - // If the mapped designated register is actually the physreg we have - // incoming, we don't need to inserted a dead copy. - if (DesignatedReg == PhysReg) { - // If this stack slot value is already available, reuse it! - if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT) - DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1; - else - DOUT << "Reusing SS#" << ReuseSlot; - DOUT << " from physreg " << TRI->getName(PhysReg) - << " for vreg" << VirtReg - << " instead of reloading into same physreg.\n"; - unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg; - MI.getOperand(i).setReg(RReg); - ReusedOperands.markClobbered(RReg); - ++NumReused; + if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg())) continue; - } - - const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg); - RegInfo->setPhysRegUsed(DesignatedReg); - ReusedOperands.markClobbered(DesignatedReg); - TII->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC); - - MachineInstr *CopyMI = prior(MII); - UpdateKills(*CopyMI, RegKills, KillOps, TRI); - - // This invalidates DesignatedReg. - Spills.ClobberPhysReg(DesignatedReg); - - Spills.addAvailable(ReuseSlot, &MI, DesignatedReg); - unsigned RReg = - SubIdx ? TRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg; - MI.getOperand(i).setReg(RReg); - DOUT << '\t' << *prior(MII); - ++NumReused; - continue; - } // if (PhysReg) - - // Otherwise, reload it and remember that we have it. - PhysReg = VRM.getPhys(VirtReg); - assert(PhysReg && "Must map virtreg to physreg!"); - - // 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, RegKills, KillOps, VRM); - - RegInfo->setPhysRegUsed(PhysReg); - ReusedOperands.markClobbered(PhysReg); - if (DoReMat) { - ReMaterialize(MBB, MII, PhysReg, VirtReg, TII, TRI, VRM); - } else { - const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg); - TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC); - MachineInstr *LoadMI = prior(MII); - VRM.addSpillSlotUse(SSorRMId, LoadMI); - ++NumLoads; - } - // This invalidates PhysReg. - Spills.ClobberPhysReg(PhysReg); - - // Any stores to this stack slot are not dead anymore. - if (!DoReMat) - MaybeDeadStores[SSorRMId] = NULL; - Spills.addAvailable(SSorRMId, &MI, PhysReg); - // Assumes this is the last use. IsKill will be unset if reg is reused - // unless it's a two-address operand. - if (TID.getOperandConstraint(i, TOI::TIED_TO) == -1) - MI.getOperand(i).setIsKill(); - unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg; - MI.getOperand(i).setReg(RReg); - UpdateKills(*prior(MII), RegKills, KillOps, TRI); - DOUT << '\t' << *prior(MII); - } - - // Ok - now we can remove stores that have been confirmed dead. - for (unsigned j = 0, e = PotentialDeadStoreSlots.size(); j != e; ++j) { - // This was the last use and the spilled value is still available - // for reuse. That means the spill was unnecessary! - int PDSSlot = PotentialDeadStoreSlots[j]; - MachineInstr* DeadStore = MaybeDeadStores[PDSSlot]; - if (DeadStore) { - DOUT << "Removed dead store:\t" << *DeadStore; - InvalidateKills(*DeadStore, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(DeadStore); - MBB.erase(DeadStore); - MaybeDeadStores[PDSSlot] = NULL; - ++NumDSE; - } - } - - - 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 - SmallSet FoldedSS; - for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) { - unsigned VirtReg = I->second.first; - VirtRegMap::ModRef MR = I->second.second; - DOUT << "Folded vreg: " << VirtReg << " MR: " << MR; - - // MI2VirtMap be can updated which invalidate the iterator. - // Increment the iterator first. - ++I; - int SS = VRM.getStackSlot(VirtReg); - if (SS == VirtRegMap::NO_STACK_SLOT) - continue; - FoldedSS.insert(SS); - DOUT << " - StackSlot: " << SS << "\n"; - - // If this folded instruction is just a use, check to see if it's a - // straight load from the virt reg slot. - if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) { - int FrameIdx; - unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx); - if (DestReg && FrameIdx == SS) { - // If this spill slot is available, turn it into a copy (or nothing) - // instead of leaving it as a load! - if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) { - DOUT << "Promoted Load To Copy: " << MI; - if (DestReg != InReg) { - const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg); - TII->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC); - MachineOperand *DefMO = MI.findRegisterDefOperand(DestReg); - unsigned SubIdx = DefMO->getSubReg(); - // 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. - // Propagate the sub-register index over. - if (SubIdx) { - DefMO = NextMII->findRegisterDefOperand(DestReg); - DefMO->setSubReg(SubIdx); - } - BackTracked = true; - } else { - DOUT << "Removing now-noop copy: " << MI; - // Unset last kill since it's being reused. - InvalidateKill(InReg, RegKills, KillOps); - } - - InvalidateKills(MI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - Erased = true; - goto ProcessNextInst; - } - } else { - unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS); - SmallVector NewMIs; - if (PhysReg && - TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) { - MBB.insert(MII, NewMIs[0]); - InvalidateKills(MI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - Erased = true; - --NextMII; // backtrack to the unfolded instruction. - BackTracked = true; - goto ProcessNextInst; - } - } - } - - // If this reference is not a use, any previous store is now dead. - // Otherwise, the store to this stack slot is not dead anymore. - MachineInstr* DeadStore = MaybeDeadStores[SS]; - if (DeadStore) { - bool isDead = !(MR & VirtRegMap::isRef); - MachineInstr *NewStore = NULL; - if (MR & VirtRegMap::isModRef) { - unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS); - SmallVector NewMIs; - // 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. - if (PhysReg && - !TII->isStoreToStackSlot(&MI, SS)) { // Not profitable! - MachineOperand *KillOpnd = - DeadStore->findRegisterUseOperand(PhysReg, true); - // Note, if the store is storing a sub-register, it's possible the - // super-register is needed below. - if (KillOpnd && !KillOpnd->getSubReg() && - TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true,NewMIs)){ - MBB.insert(MII, NewMIs[0]); - NewStore = NewMIs[1]; - MBB.insert(MII, NewStore); - VRM.addSpillSlotUse(SS, NewStore); - InvalidateKills(MI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - Erased = true; - --NextMII; - --NextMII; // backtrack to the unfolded instruction. - BackTracked = true; - isDead = true; + unsigned VirtReg = MO.getReg(); + unsigned PhysReg = VRM->getPhys(VirtReg); + assert(PhysReg != VirtRegMap::NO_PHYS_REG && + "Instruction uses unmapped VirtReg"); + assert(!MRI->isReserved(PhysReg) && "Reserved register assignment"); + + // Preserve semantics of sub-register operands. + if (MO.getSubReg()) { + // A virtual register kill refers to the whole register, so we may + // have to add operands for the super-register. A + // partial redef always kills and redefines the super-register. + if (NoSubRegLiveness && MO.readsReg() + && (MO.isDef() || MO.isKill())) + SuperKills.push_back(PhysReg); + + if (MO.isDef()) { + // The flag only makes sense for sub-register defs, and + // we are substituting a full physreg. An operand + // from the SuperKills list will represent the partial read of the + // super-register. + MO.setIsUndef(false); + + // Also add implicit defs for the super-register. + if (NoSubRegLiveness) { + if (MO.isDead()) + SuperDeads.push_back(PhysReg); + else + SuperDefs.push_back(PhysReg); } } - } - - if (isDead) { // Previous store is dead. - // If we get here, the store is dead, nuke it now. - DOUT << "Removed dead store:\t" << *DeadStore; - InvalidateKills(*DeadStore, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(DeadStore); - MBB.erase(DeadStore); - if (!NewStore) - ++NumDSE; - } - MaybeDeadStores[SS] = NULL; - if (NewStore) { - // Treat this store as a spill merged into a copy. That makes the - // stack slot value available. - VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod); - goto ProcessNextInst; + // PhysReg operands cannot have subregister indexes. + PhysReg = TRI->getSubReg(PhysReg, MO.getSubReg()); + assert(PhysReg && "Invalid SubReg for physical register"); + MO.setSubReg(0); } + // Rewrite. Note we could have used MachineOperand::substPhysReg(), but + // we need the inlining here. + MO.setReg(PhysReg); } - // 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.ModifyStackSlotOrReMat(SS); - - // If this is *just* a mod of the value, check to see if this is just a - // store to the spill slot (i.e. the spill got merged into the copy). If - // so, realize that the vreg is available now, and add the store to the - // MaybeDeadStore info. - int StackSlot; - if (!(MR & VirtRegMap::isRef)) { - if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) { - assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) && - "Src hasn't been allocated yet?"); + // Add any missing super-register kills after rewriting the whole + // instruction. + while (!SuperKills.empty()) + MI->addRegisterKilled(SuperKills.pop_back_val(), TRI, true); - if (CommuteToFoldReload(MBB, MII, VirtReg, SrcReg, StackSlot, - RegKills, KillOps, TRI, VRM)) { - NextMII = next(MII); - BackTracked = true; - goto ProcessNextInst; - } + while (!SuperDeads.empty()) + MI->addRegisterDead(SuperDeads.pop_back_val(), TRI, true); - // 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; + while (!SuperDefs.empty()) + MI->addRegisterDefined(SuperDefs.pop_back_val(), TRI); - // If the stack slot value was previously available in some other - // register, change it now. Otherwise, make the register - // available in PhysReg. - Spills.addAvailable(StackSlot, &MI, SrcReg, false/*!clobber*/); - } + DEBUG(dbgs() << "> " << *MI); + + // Finally, remove any identity copies. + if (MI->isIdentityCopy()) { + ++NumIdCopies; + if (MI->getNumOperands() == 2) { + DEBUG(dbgs() << "Deleting identity copy.\n"); + if (Indexes) + Indexes->removeMachineInstrFromMaps(MI); + // It's safe to erase MI because MII has already been incremented. + MI->eraseFromParent(); + } else { + // Transform identity copy to a KILL to deal with subregisters. + MI->setDesc(TII->get(TargetOpcode::KILL)); + DEBUG(dbgs() << "Identity copy: " << *MI); } } } + } - // Process all of the spilled defs. - for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI.getOperand(i); - if (!(MO.isReg() && MO.getReg() && MO.isDef())) - continue; - - unsigned VirtReg = MO.getReg(); - if (!TargetRegisterInfo::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, SrcSR, DstSR; - if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) { - ++NumDCE; - DOUT << "Removing now-noop copy: " << MI; - SmallVector KillRegs; - InvalidateKills(MI, RegKills, KillOps, &KillRegs); - if (MO.isDead() && !KillRegs.empty()) { - // Source register or an implicit super/sub-register use is killed. - assert(KillRegs[0] == Dst || - TRI->isSubRegister(KillRegs[0], Dst) || - TRI->isSuperRegister(KillRegs[0], Dst)); - // Last def is now dead. - TransferDeadness(&MBB, Dist, Src, RegKills, KillOps); - } - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - Erased = true; - Spills.disallowClobberPhysReg(VirtReg); - goto ProcessNextInst; - } - - // If it's not a no-op copy, it clobbers the value in the destreg. - Spills.ClobberPhysReg(VirtReg); - ReusedOperands.markClobbered(VirtReg); - - // Check to see if this instruction is a load from a stack slot into - // a register. If so, this provides the stack slot value in the reg. - int FrameIdx; - if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) { - assert(DestReg == VirtReg && "Unknown load situation!"); - - // If it is a folded reference, then it's not safe to clobber. - bool Folded = FoldedSS.count(FrameIdx); - // Otherwise, if it wasn't available, remember that it is now! - Spills.addAvailable(FrameIdx, &MI, DestReg, !Folded); - goto ProcessNextInst; - } - + // Tell MRI about physical registers in use. + if (NoReturnInsts.empty()) { + for (SparseSet::iterator + RegI = PhysRegs.begin(), E = PhysRegs.end(); RegI != E; ++RegI) + if (!MRI->reg_nodbg_empty(*RegI)) + MRI->setPhysRegUsed(*RegI); + } else { + for (SparseSet::iterator + I = PhysRegs.begin(), E = PhysRegs.end(); I != E; ++I) { + unsigned Reg = *I; + if (MRI->reg_nodbg_empty(Reg)) continue; - } - - unsigned SubIdx = MO.getSubReg(); - bool DoReMat = VRM.isReMaterialized(VirtReg); - if (DoReMat) - ReMatDefs.insert(&MI); - - // The only vregs left are stack slot definitions. - int StackSlot = VRM.getStackSlot(VirtReg); - const TargetRegisterClass *RC = RegInfo->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.getDesc().findTiedToSrcOperand(i); - if (TiedOp != -1) { - PhysReg = MI.getOperand(TiedOp).getReg(); - if (SubIdx) { - unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, TRI); - assert(SuperReg && TRI->getSubReg(SuperReg, SubIdx) == PhysReg && - "Can't find corresponding super-register!"); - PhysReg = SuperReg; - } - } else { - PhysReg = VRM.getPhys(VirtReg); - if (ReusedOperands.isClobbered(PhysReg)) { - // Another def has taken the assigned physreg. It must have been a - // use&def which got it due to reuse. Undo the reuse! - PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI, - Spills, MaybeDeadStores, RegKills, KillOps, VRM); + // Check if this register has a use that will impact the rest of the + // code. Uses in debug and noreturn instructions do not impact the + // generated code. + for (MachineInstr &It : MRI->reg_nodbg_instructions(Reg)) { + if (!NoReturnInsts.count(&It)) { + MRI->setPhysRegUsed(Reg); + break; } } - - assert(PhysReg && "VR not assigned a physical register?"); - RegInfo->setPhysRegUsed(PhysReg); - unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg; - ReusedOperands.markClobbered(RReg); - MI.getOperand(i).setReg(RReg); - - if (!MO.isDead()) { - MachineInstr *&LastStore = MaybeDeadStores[StackSlot]; - SpillRegToStackSlot(MBB, MII, -1, PhysReg, StackSlot, RC, true, - LastStore, Spills, ReMatDefs, RegKills, KillOps, VRM); - NextMII = next(MII); - - // 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, SrcSR, DstSR; - if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) { - ++NumDCE; - DOUT << "Removing now-noop copy: " << MI; - InvalidateKills(MI, RegKills, KillOps); - VRM.RemoveMachineInstrFromMaps(&MI); - MBB.erase(&MI); - Erased = true; - UpdateKills(*LastStore, RegKills, KillOps, TRI); - goto ProcessNextInst; - } - } - } - } - ProcessNextInst: - DistanceMap.insert(std::make_pair(&MI, Dist++)); - if (!Erased && !BackTracked) { - for (MachineBasicBlock::iterator II = &MI; II != NextMII; ++II) - UpdateKills(*II, RegKills, KillOps, TRI); } - MII = NextMII; } } -llvm::Spiller* llvm::createSpiller() { - switch (SpillerOpt) { - default: assert(0 && "Unreachable!"); - case local: - return new LocalSpiller(); - case simple: - return new SimpleSpiller(); - } -}