X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FTargetInstrInfoImpl.cpp;h=86e71d8ccbb612ea309aecb496eb383a9412496c;hb=0e6a052331f674dd70e28af41f654a7874405eab;hp=598b94af9c41e6f13056b623720813ebba7d2695;hpb=a4d16a1f0dcdd1ab2862737105f900e2c577532d;p=oota-llvm.git diff --git a/lib/CodeGen/TargetInstrInfoImpl.cpp b/lib/CodeGen/TargetInstrInfoImpl.cpp index 598b94af9c4..86e71d8ccbb 100644 --- a/lib/CodeGen/TargetInstrInfoImpl.cpp +++ b/lib/CodeGen/TargetInstrInfoImpl.cpp @@ -13,43 +13,136 @@ //===----------------------------------------------------------------------===// #include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Target/TargetLowering.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineInstr.h" +#include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/CodeGen/MachineMemOperand.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/ScoreboardHazardRecognizer.h" +#include "llvm/CodeGen/PseudoSourceValue.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" using namespace llvm; +static cl::opt DisableHazardRecognizer( + "disable-sched-hazard", cl::Hidden, cl::init(false), + cl::desc("Disable hazard detection during preRA scheduling")); + +/// ReplaceTailWithBranchTo - Delete the instruction OldInst and everything +/// after it, replacing it with an unconditional branch to NewDest. +void +TargetInstrInfoImpl::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail, + MachineBasicBlock *NewDest) const { + MachineBasicBlock *MBB = Tail->getParent(); + + // Remove all the old successors of MBB from the CFG. + while (!MBB->succ_empty()) + MBB->removeSuccessor(MBB->succ_begin()); + + // Remove all the dead instructions from the end of MBB. + MBB->erase(Tail, MBB->end()); + + // If MBB isn't immediately before MBB, insert a branch to it. + if (++MachineFunction::iterator(MBB) != MachineFunction::iterator(NewDest)) + InsertBranch(*MBB, NewDest, 0, SmallVector(), + Tail->getDebugLoc()); + MBB->addSuccessor(NewDest); +} + // commuteInstruction - The default implementation of this method just exchanges -// operand 1 and 2. -MachineInstr *TargetInstrInfoImpl::commuteInstruction(MachineInstr *MI) const { - assert(MI->getOperand(1).isRegister() && MI->getOperand(2).isRegister() && +// the two operands returned by findCommutedOpIndices. +MachineInstr *TargetInstrInfoImpl::commuteInstruction(MachineInstr *MI, + bool NewMI) const { + const MCInstrDesc &MCID = MI->getDesc(); + bool HasDef = MCID.getNumDefs(); + if (HasDef && !MI->getOperand(0).isReg()) + // No idea how to commute this instruction. Target should implement its own. + return 0; + unsigned Idx1, Idx2; + if (!findCommutedOpIndices(MI, Idx1, Idx2)) { + std::string msg; + raw_string_ostream Msg(msg); + Msg << "Don't know how to commute: " << *MI; + report_fatal_error(Msg.str()); + } + + assert(MI->getOperand(Idx1).isReg() && MI->getOperand(Idx2).isReg() && "This only knows how to commute register operands so far"); - unsigned Reg1 = MI->getOperand(1).getReg(); - unsigned Reg2 = MI->getOperand(2).getReg(); - MachineOperand &MO = MI->getOperand(0); - bool UpdateReg0 = MO.isReg() && MO.getReg() == Reg1; - bool Reg1IsKill = MI->getOperand(1).isKill(); - bool Reg2IsKill = MI->getOperand(2).isKill(); - if (UpdateReg0) { + unsigned Reg1 = MI->getOperand(Idx1).getReg(); + unsigned Reg2 = MI->getOperand(Idx2).getReg(); + bool Reg1IsKill = MI->getOperand(Idx1).isKill(); + bool Reg2IsKill = MI->getOperand(Idx2).isKill(); + bool ChangeReg0 = false; + if (HasDef && MI->getOperand(0).getReg() == Reg1) { // Must be two address instruction! - assert(MI->getDesc().getOperandConstraint(0, TOI::TIED_TO) && + assert(MI->getDesc().getOperandConstraint(0, MCOI::TIED_TO) && "Expecting a two-address instruction!"); Reg2IsKill = false; - MI->getOperand(0).setReg(Reg2); + ChangeReg0 = true; + } + + if (NewMI) { + // Create a new instruction. + unsigned Reg0 = HasDef + ? (ChangeReg0 ? Reg2 : MI->getOperand(0).getReg()) : 0; + bool Reg0IsDead = HasDef ? MI->getOperand(0).isDead() : false; + MachineFunction &MF = *MI->getParent()->getParent(); + if (HasDef) + return BuildMI(MF, MI->getDebugLoc(), MI->getDesc()) + .addReg(Reg0, RegState::Define | getDeadRegState(Reg0IsDead)) + .addReg(Reg2, getKillRegState(Reg2IsKill)) + .addReg(Reg1, getKillRegState(Reg2IsKill)); + else + return BuildMI(MF, MI->getDebugLoc(), MI->getDesc()) + .addReg(Reg2, getKillRegState(Reg2IsKill)) + .addReg(Reg1, getKillRegState(Reg2IsKill)); } - MI->getOperand(2).setReg(Reg1); - MI->getOperand(1).setReg(Reg2); - MI->getOperand(2).setIsKill(Reg1IsKill); - MI->getOperand(1).setIsKill(Reg2IsKill); + + if (ChangeReg0) + MI->getOperand(0).setReg(Reg2); + MI->getOperand(Idx2).setReg(Reg1); + MI->getOperand(Idx1).setReg(Reg2); + MI->getOperand(Idx2).setIsKill(Reg1IsKill); + MI->getOperand(Idx1).setIsKill(Reg2IsKill); return MI; } +/// findCommutedOpIndices - If specified MI is commutable, return the two +/// operand indices that would swap value. Return true if the instruction +/// is not in a form which this routine understands. +bool TargetInstrInfoImpl::findCommutedOpIndices(MachineInstr *MI, + unsigned &SrcOpIdx1, + unsigned &SrcOpIdx2) const { + const MCInstrDesc &MCID = MI->getDesc(); + if (!MCID.isCommutable()) + return false; + // This assumes v0 = op v1, v2 and commuting would swap v1 and v2. If this + // is not true, then the target must implement this. + SrcOpIdx1 = MCID.getNumDefs(); + SrcOpIdx2 = SrcOpIdx1 + 1; + if (!MI->getOperand(SrcOpIdx1).isReg() || + !MI->getOperand(SrcOpIdx2).isReg()) + // No idea. + return false; + return true; +} + + bool TargetInstrInfoImpl::PredicateInstruction(MachineInstr *MI, - const std::vector &Pred) const { + const SmallVectorImpl &Pred) const { bool MadeChange = false; - const TargetInstrDesc &TID = MI->getDesc(); - if (!TID.isPredicable()) + const MCInstrDesc &MCID = MI->getDesc(); + if (!MCID.isPredicable()) return false; - + for (unsigned j = 0, i = 0, e = MI->getNumOperands(); i != e; ++i) { - if (TID.OpInfo[i].isPredicate()) { + if (MCID.OpInfo[i].isPredicate()) { MachineOperand &MO = MI->getOperand(i); if (MO.isReg()) { MO.setReg(Pred[j].getReg()); @@ -66,3 +159,285 @@ bool TargetInstrInfoImpl::PredicateInstruction(MachineInstr *MI, } return MadeChange; } + +void TargetInstrInfoImpl::reMaterialize(MachineBasicBlock &MBB, + MachineBasicBlock::iterator I, + unsigned DestReg, + unsigned SubIdx, + const MachineInstr *Orig, + const TargetRegisterInfo &TRI) const { + MachineInstr *MI = MBB.getParent()->CloneMachineInstr(Orig); + MI->substituteRegister(MI->getOperand(0).getReg(), DestReg, SubIdx, TRI); + MBB.insert(I, MI); +} + +bool +TargetInstrInfoImpl::produceSameValue(const MachineInstr *MI0, + const MachineInstr *MI1, + const MachineRegisterInfo *MRI) const { + return MI0->isIdenticalTo(MI1, MachineInstr::IgnoreVRegDefs); +} + +MachineInstr *TargetInstrInfoImpl::duplicate(MachineInstr *Orig, + MachineFunction &MF) const { + assert(!Orig->getDesc().isNotDuplicable() && + "Instruction cannot be duplicated"); + return MF.CloneMachineInstr(Orig); +} + +// If the COPY instruction in MI can be folded to a stack operation, return +// the register class to use. +static const TargetRegisterClass *canFoldCopy(const MachineInstr *MI, + unsigned FoldIdx) { + assert(MI->isCopy() && "MI must be a COPY instruction"); + if (MI->getNumOperands() != 2) + return 0; + assert(FoldIdx<2 && "FoldIdx refers no nonexistent operand"); + + const MachineOperand &FoldOp = MI->getOperand(FoldIdx); + const MachineOperand &LiveOp = MI->getOperand(1-FoldIdx); + + if (FoldOp.getSubReg() || LiveOp.getSubReg()) + return 0; + + unsigned FoldReg = FoldOp.getReg(); + unsigned LiveReg = LiveOp.getReg(); + + assert(TargetRegisterInfo::isVirtualRegister(FoldReg) && + "Cannot fold physregs"); + + const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo(); + const TargetRegisterClass *RC = MRI.getRegClass(FoldReg); + + if (TargetRegisterInfo::isPhysicalRegister(LiveOp.getReg())) + return RC->contains(LiveOp.getReg()) ? RC : 0; + + if (RC->hasSubClassEq(MRI.getRegClass(LiveReg))) + return RC; + + // FIXME: Allow folding when register classes are memory compatible. + return 0; +} + +bool TargetInstrInfoImpl:: +canFoldMemoryOperand(const MachineInstr *MI, + const SmallVectorImpl &Ops) const { + return MI->isCopy() && Ops.size() == 1 && canFoldCopy(MI, Ops[0]); +} + +/// foldMemoryOperand - Attempt to fold a load or store of the specified stack +/// slot into the specified machine instruction for the specified operand(s). +/// If this is possible, a new instruction is returned with the specified +/// operand folded, otherwise NULL is returned. The client is responsible for +/// removing the old instruction and adding the new one in the instruction +/// stream. +MachineInstr* +TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI, + const SmallVectorImpl &Ops, + int FI) const { + unsigned Flags = 0; + for (unsigned i = 0, e = Ops.size(); i != e; ++i) + if (MI->getOperand(Ops[i]).isDef()) + Flags |= MachineMemOperand::MOStore; + else + Flags |= MachineMemOperand::MOLoad; + + MachineBasicBlock *MBB = MI->getParent(); + assert(MBB && "foldMemoryOperand needs an inserted instruction"); + MachineFunction &MF = *MBB->getParent(); + + // Ask the target to do the actual folding. + if (MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, FI)) { + // Add a memory operand, foldMemoryOperandImpl doesn't do that. + assert((!(Flags & MachineMemOperand::MOStore) || + NewMI->getDesc().mayStore()) && + "Folded a def to a non-store!"); + assert((!(Flags & MachineMemOperand::MOLoad) || + NewMI->getDesc().mayLoad()) && + "Folded a use to a non-load!"); + const MachineFrameInfo &MFI = *MF.getFrameInfo(); + assert(MFI.getObjectOffset(FI) != -1); + MachineMemOperand *MMO = + MF.getMachineMemOperand( + MachinePointerInfo(PseudoSourceValue::getFixedStack(FI)), + Flags, MFI.getObjectSize(FI), + MFI.getObjectAlignment(FI)); + NewMI->addMemOperand(MF, MMO); + + // FIXME: change foldMemoryOperandImpl semantics to also insert NewMI. + return MBB->insert(MI, NewMI); + } + + // Straight COPY may fold as load/store. + if (!MI->isCopy() || Ops.size() != 1) + return 0; + + const TargetRegisterClass *RC = canFoldCopy(MI, Ops[0]); + if (!RC) + return 0; + + const MachineOperand &MO = MI->getOperand(1-Ops[0]); + MachineBasicBlock::iterator Pos = MI; + const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo(); + + if (Flags == MachineMemOperand::MOStore) + storeRegToStackSlot(*MBB, Pos, MO.getReg(), MO.isKill(), FI, RC, TRI); + else + loadRegFromStackSlot(*MBB, Pos, MO.getReg(), FI, RC, TRI); + return --Pos; +} + +/// foldMemoryOperand - Same as the previous version except it allows folding +/// of any load and store from / to any address, not just from a specific +/// stack slot. +MachineInstr* +TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI, + const SmallVectorImpl &Ops, + MachineInstr* LoadMI) const { + assert(LoadMI->getDesc().canFoldAsLoad() && "LoadMI isn't foldable!"); +#ifndef NDEBUG + for (unsigned i = 0, e = Ops.size(); i != e; ++i) + assert(MI->getOperand(Ops[i]).isUse() && "Folding load into def!"); +#endif + MachineBasicBlock &MBB = *MI->getParent(); + MachineFunction &MF = *MBB.getParent(); + + // Ask the target to do the actual folding. + MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, LoadMI); + if (!NewMI) return 0; + + NewMI = MBB.insert(MI, NewMI); + + // Copy the memoperands from the load to the folded instruction. + NewMI->setMemRefs(LoadMI->memoperands_begin(), + LoadMI->memoperands_end()); + + return NewMI; +} + +bool TargetInstrInfo:: +isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI, + AliasAnalysis *AA) const { + const MachineFunction &MF = *MI->getParent()->getParent(); + const MachineRegisterInfo &MRI = MF.getRegInfo(); + const TargetMachine &TM = MF.getTarget(); + const TargetInstrInfo &TII = *TM.getInstrInfo(); + const TargetRegisterInfo &TRI = *TM.getRegisterInfo(); + + // A load from a fixed stack slot can be rematerialized. This may be + // redundant with subsequent checks, but it's target-independent, + // simple, and a common case. + int FrameIdx = 0; + if (TII.isLoadFromStackSlot(MI, FrameIdx) && + MF.getFrameInfo()->isImmutableObjectIndex(FrameIdx)) + return true; + + const MCInstrDesc &MCID = MI->getDesc(); + + // Avoid instructions obviously unsafe for remat. + if (MCID.isNotDuplicable() || MCID.mayStore() || + MI->hasUnmodeledSideEffects()) + return false; + + // Don't remat inline asm. We have no idea how expensive it is + // even if it's side effect free. + if (MI->isInlineAsm()) + return false; + + // Avoid instructions which load from potentially varying memory. + if (MCID.mayLoad() && !MI->isInvariantLoad(AA)) + return false; + + // If any of the registers accessed are non-constant, conservatively assume + // the instruction is not rematerializable. + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { + const MachineOperand &MO = MI->getOperand(i); + if (!MO.isReg()) continue; + unsigned Reg = MO.getReg(); + if (Reg == 0) + continue; + + // Check for a well-behaved physical register. + if (TargetRegisterInfo::isPhysicalRegister(Reg)) { + if (MO.isUse()) { + // If the physreg has no defs anywhere, it's just an ambient register + // and we can freely move its uses. Alternatively, if it's allocatable, + // it could get allocated to something with a def during allocation. + if (!MRI.def_empty(Reg)) + return false; + BitVector AllocatableRegs = TRI.getAllocatableSet(MF, 0); + if (AllocatableRegs.test(Reg)) + return false; + // Check for a def among the register's aliases too. + for (const unsigned *Alias = TRI.getAliasSet(Reg); *Alias; ++Alias) { + unsigned AliasReg = *Alias; + if (!MRI.def_empty(AliasReg)) + return false; + if (AllocatableRegs.test(AliasReg)) + return false; + } + } else { + // A physreg def. We can't remat it. + return false; + } + continue; + } + + // Only allow one virtual-register def, and that in the first operand. + if (MO.isDef() != (i == 0)) + return false; + + // Don't allow any virtual-register uses. Rematting an instruction with + // virtual register uses would length the live ranges of the uses, which + // is not necessarily a good idea, certainly not "trivial". + if (MO.isUse()) + return false; + } + + // Everything checked out. + return true; +} + +/// isSchedulingBoundary - Test if the given instruction should be +/// considered a scheduling boundary. This primarily includes labels +/// and terminators. +bool TargetInstrInfoImpl::isSchedulingBoundary(const MachineInstr *MI, + const MachineBasicBlock *MBB, + const MachineFunction &MF) const{ + // Terminators and labels can't be scheduled around. + if (MI->getDesc().isTerminator() || MI->isLabel()) + return true; + + // Don't attempt to schedule around any instruction that defines + // a stack-oriented pointer, as it's unlikely to be profitable. This + // saves compile time, because it doesn't require every single + // stack slot reference to depend on the instruction that does the + // modification. + const TargetLowering &TLI = *MF.getTarget().getTargetLowering(); + if (MI->definesRegister(TLI.getStackPointerRegisterToSaveRestore())) + return true; + + return false; +} + +// Provide a global flag for disabling the PreRA hazard recognizer that targets +// may choose to honor. +bool TargetInstrInfoImpl::usePreRAHazardRecognizer() const { + return !DisableHazardRecognizer; +} + +// Default implementation of CreateTargetRAHazardRecognizer. +ScheduleHazardRecognizer *TargetInstrInfoImpl:: +CreateTargetHazardRecognizer(const TargetMachine *TM, + const ScheduleDAG *DAG) const { + // Dummy hazard recognizer allows all instructions to issue. + return new ScheduleHazardRecognizer(); +} + +// Default implementation of CreateTargetPostRAHazardRecognizer. +ScheduleHazardRecognizer *TargetInstrInfoImpl:: +CreateTargetPostRAHazardRecognizer(const InstrItineraryData *II, + const ScheduleDAG *DAG) const { + return (ScheduleHazardRecognizer *) + new ScoreboardHazardRecognizer(II, DAG, "post-RA-sched"); +}