diff options
Diffstat (limited to 'contrib/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp | 593 |
1 files changed, 318 insertions, 275 deletions
diff --git a/contrib/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/contrib/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp index a9058bc..e6dfe10 100644 --- a/contrib/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp +++ b/contrib/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp @@ -29,26 +29,25 @@ #define DEBUG_TYPE "twoaddrinstr" #include "llvm/CodeGen/Passes.h" -#include "llvm/Function.h" +#include "llvm/ADT/BitVector.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/CodeGen/LiveIntervalAnalysis.h" #include "llvm/CodeGen/LiveVariables.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineInstr.h" #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/IR/Function.h" #include "llvm/MC/MCInstrItineraries.h" -#include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetOptions.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" -#include "llvm/ADT/BitVector.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/SmallSet.h" -#include "llvm/ADT/Statistic.h" -#include "llvm/ADT/STLExtras.h" +#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetRegisterInfo.h" using namespace llvm; STATISTIC(NumTwoAddressInstrs, "Number of two-address instructions"); @@ -67,7 +66,6 @@ class TwoAddressInstructionPass : public MachineFunctionPass { const InstrItineraryData *InstrItins; MachineRegisterInfo *MRI; LiveVariables *LV; - SlotIndexes *Indexes; LiveIntervals *LIS; AliasAnalysis *AA; CodeGenOpt::Level OptLevel; @@ -92,10 +90,6 @@ class TwoAddressInstructionPass : public MachineFunctionPass { // virtual registers. e.g. r1 = move v1024. DenseMap<unsigned, unsigned> DstRegMap; - /// RegSequences - Keep track the list of REG_SEQUENCE instructions seen - /// during the initial walk of the machine function. - SmallVector<MachineInstr*, 16> RegSequences; - bool sink3AddrInstruction(MachineInstr *MI, unsigned Reg, MachineBasicBlock::iterator OldPos); @@ -125,7 +119,7 @@ class TwoAddressInstructionPass : public MachineFunctionPass { bool tryInstructionTransform(MachineBasicBlock::iterator &mi, MachineBasicBlock::iterator &nmi, unsigned SrcIdx, unsigned DstIdx, - unsigned Dist); + unsigned Dist, bool shouldOnlyCommute); void scanUses(unsigned DstReg); @@ -135,11 +129,7 @@ class TwoAddressInstructionPass : public MachineFunctionPass { typedef SmallDenseMap<unsigned, TiedPairList> TiedOperandMap; bool collectTiedOperands(MachineInstr *MI, TiedOperandMap&); void processTiedPairs(MachineInstr *MI, TiedPairList&, unsigned &Dist); - - /// eliminateRegSequences - Eliminate REG_SEQUENCE instructions as part of - /// the de-ssa process. This replaces sources of REG_SEQUENCE as sub-register - /// references of the register defined by REG_SEQUENCE. - bool eliminateRegSequences(); + void eliminateRegSequence(MachineBasicBlock::iterator&); public: static char ID; // Pass identification, replacement for typeid @@ -172,6 +162,8 @@ INITIALIZE_PASS_END(TwoAddressInstructionPass, "twoaddressinstruction", char &llvm::TwoAddressInstructionPassID = TwoAddressInstructionPass::ID; +static bool isPlainlyKilled(MachineInstr *MI, unsigned Reg, LiveIntervals *LIS); + /// sink3AddrInstruction - A two-address instruction has been converted to a /// three-address instruction to avoid clobbering a register. Try to sink it /// past the instruction that would kill the above mentioned register to reduce @@ -213,14 +205,29 @@ sink3AddrInstruction(MachineInstr *MI, unsigned SavedReg, // Find the instruction that kills SavedReg. MachineInstr *KillMI = NULL; - for (MachineRegisterInfo::use_nodbg_iterator - UI = MRI->use_nodbg_begin(SavedReg), - UE = MRI->use_nodbg_end(); UI != UE; ++UI) { - MachineOperand &UseMO = UI.getOperand(); - if (!UseMO.isKill()) - continue; - KillMI = UseMO.getParent(); - break; + if (LIS) { + LiveInterval &LI = LIS->getInterval(SavedReg); + assert(LI.end() != LI.begin() && + "Reg should not have empty live interval."); + + SlotIndex MBBEndIdx = LIS->getMBBEndIdx(MBB).getPrevSlot(); + LiveInterval::const_iterator I = LI.find(MBBEndIdx); + if (I != LI.end() && I->start < MBBEndIdx) + return false; + + --I; + KillMI = LIS->getInstructionFromIndex(I->end); + } + if (!KillMI) { + for (MachineRegisterInfo::use_nodbg_iterator + UI = MRI->use_nodbg_begin(SavedReg), + UE = MRI->use_nodbg_end(); UI != UE; ++UI) { + MachineOperand &UseMO = UI.getOperand(); + if (!UseMO.isKill()) + continue; + KillMI = UseMO.getParent(); + break; + } } // If we find the instruction that kills SavedReg, and it is in an @@ -259,7 +266,7 @@ sink3AddrInstruction(MachineInstr *MI, unsigned SavedReg, if (DefReg == MOReg) return false; - if (MO.isKill()) { + if (MO.isKill() || (LIS && isPlainlyKilled(OtherMI, MOReg, LIS))) { if (OtherMI == KillMI && MOReg == SavedReg) // Save the operand that kills the register. We want to unset the kill // marker if we can sink MI past it. @@ -272,13 +279,15 @@ sink3AddrInstruction(MachineInstr *MI, unsigned SavedReg, } assert(KillMO && "Didn't find kill"); - // Update kill and LV information. - KillMO->setIsKill(false); - KillMO = MI->findRegisterUseOperand(SavedReg, false, TRI); - KillMO->setIsKill(true); + if (!LIS) { + // Update kill and LV information. + KillMO->setIsKill(false); + KillMO = MI->findRegisterUseOperand(SavedReg, false, TRI); + KillMO->setIsKill(true); - if (LV) - LV->replaceKillInstruction(SavedReg, KillMI, MI); + if (LV) + LV->replaceKillInstruction(SavedReg, KillMI, MI); + } // Move instruction to its destination. MBB->remove(MI); @@ -339,6 +348,33 @@ static bool isCopyToReg(MachineInstr &MI, const TargetInstrInfo *TII, return true; } +/// isPLainlyKilled - Test if the given register value, which is used by the +// given instruction, is killed by the given instruction. +static bool isPlainlyKilled(MachineInstr *MI, unsigned Reg, + LiveIntervals *LIS) { + if (LIS && TargetRegisterInfo::isVirtualRegister(Reg) && + !LIS->isNotInMIMap(MI)) { + // FIXME: Sometimes tryInstructionTransform() will add instructions and + // test whether they can be folded before keeping them. In this case it + // sets a kill before recursively calling tryInstructionTransform() again. + // If there is no interval available, we assume that this instruction is + // one of those. A kill flag is manually inserted on the operand so the + // check below will handle it. + LiveInterval &LI = LIS->getInterval(Reg); + // This is to match the kill flag version where undefs don't have kill + // flags. + if (!LI.hasAtLeastOneValue()) + return false; + + SlotIndex useIdx = LIS->getInstructionIndex(MI); + LiveInterval::const_iterator I = LI.find(useIdx); + assert(I != LI.end() && "Reg must be live-in to use."); + return !I->end.isBlock() && SlotIndex::isSameInstr(I->end, useIdx); + } + + return MI->killsRegister(Reg); +} + /// isKilled - Test if the given register value, which is used by the given /// instruction, is killed by the given instruction. This looks through /// coalescable copies to see if the original value is potentially not killed. @@ -354,12 +390,20 @@ static bool isCopyToReg(MachineInstr &MI, const TargetInstrInfo *TII, /// normal heuristics commute the (two-address) add, which lets /// coalescing eliminate the extra copy. /// +/// If allowFalsePositives is true then likely kills are treated as kills even +/// if it can't be proven that they are kills. static bool isKilled(MachineInstr &MI, unsigned Reg, const MachineRegisterInfo *MRI, - const TargetInstrInfo *TII) { + const TargetInstrInfo *TII, + LiveIntervals *LIS, + bool allowFalsePositives) { MachineInstr *DefMI = &MI; for (;;) { - if (!DefMI->killsRegister(Reg)) + // All uses of physical registers are likely to be kills. + if (TargetRegisterInfo::isPhysicalRegister(Reg) && + (allowFalsePositives || MRI->hasOneUse(Reg))) + return true; + if (!isPlainlyKilled(DefMI, Reg, LIS)) return false; if (TargetRegisterInfo::isPhysicalRegister(Reg)) return true; @@ -480,7 +524,7 @@ isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC, // insert => %reg1030<def> = MOV8rr %reg1029 // %reg1030<def> = ADD8rr %reg1029<kill>, %reg1028<kill>, %EFLAGS<imp-def,dead> - if (!MI->killsRegister(regC)) + if (!isPlainlyKilled(MI, regC, LIS)) return false; // Ok, we have something like: @@ -536,19 +580,9 @@ commuteInstruction(MachineBasicBlock::iterator &mi, } DEBUG(dbgs() << "2addr: COMMUTED TO: " << *NewMI); - // If the instruction changed to commute it, update livevar. - if (NewMI != MI) { - if (LV) - // Update live variables - LV->replaceKillInstruction(RegC, MI, NewMI); - if (Indexes) - Indexes->replaceMachineInstrInMaps(MI, NewMI); - - MBB->insert(mi, NewMI); // Insert the new inst - MBB->erase(mi); // Nuke the old inst. - mi = NewMI; - DistanceMap.insert(std::make_pair(NewMI, Dist)); - } + assert(NewMI == MI && + "TargetInstrInfo::commuteInstruction() should not return a new " + "instruction unless it was requested."); // Update source register map. unsigned FromRegC = getMappedReg(RegC, SrcRegMap); @@ -595,8 +629,8 @@ TwoAddressInstructionPass::convertInstTo3Addr(MachineBasicBlock::iterator &mi, DEBUG(dbgs() << "2addr: TO 3-ADDR: " << *NewMI); bool Sunk = false; - if (Indexes) - Indexes->replaceMachineInstrInMaps(mi, NewMI); + if (LIS) + LIS->ReplaceMachineInstrInMaps(mi, NewMI); if (NewMI->findRegisterUseOperand(RegB, false, TRI)) // FIXME: Temporary workaround. If the new instruction doesn't @@ -708,9 +742,9 @@ bool TwoAddressInstructionPass:: rescheduleMIBelowKill(MachineBasicBlock::iterator &mi, MachineBasicBlock::iterator &nmi, unsigned Reg) { - // Bail immediately if we don't have LV available. We use it to find kills - // efficiently. - if (!LV) + // Bail immediately if we don't have LV or LIS available. We use them to find + // kills efficiently. + if (!LV && !LIS) return false; MachineInstr *MI = &*mi; @@ -719,7 +753,22 @@ rescheduleMIBelowKill(MachineBasicBlock::iterator &mi, // Must be created from unfolded load. Don't waste time trying this. return false; - MachineInstr *KillMI = LV->getVarInfo(Reg).findKill(MBB); + MachineInstr *KillMI = 0; + if (LIS) { + LiveInterval &LI = LIS->getInterval(Reg); + assert(LI.end() != LI.begin() && + "Reg should not have empty live interval."); + + SlotIndex MBBEndIdx = LIS->getMBBEndIdx(MBB).getPrevSlot(); + LiveInterval::const_iterator I = LI.find(MBBEndIdx); + if (I != LI.end() && I->start < MBBEndIdx) + return false; + + --I; + KillMI = LIS->getInstructionFromIndex(I->end); + } else { + KillMI = LV->getVarInfo(Reg).findKill(MBB); + } if (!KillMI || MI == KillMI || KillMI->isCopy() || KillMI->isCopyLike()) // Don't mess with copies, they may be coalesced later. return false; @@ -755,24 +804,27 @@ rescheduleMIBelowKill(MachineBasicBlock::iterator &mi, Defs.insert(MOReg); else { Uses.insert(MOReg); - if (MO.isKill() && MOReg != Reg) + if (MOReg != Reg && (MO.isKill() || + (LIS && isPlainlyKilled(MI, MOReg, LIS)))) Kills.insert(MOReg); } } // Move the copies connected to MI down as well. - MachineBasicBlock::iterator From = MI; - MachineBasicBlock::iterator To = llvm::next(From); - while (To->isCopy() && Defs.count(To->getOperand(1).getReg())) { - Defs.insert(To->getOperand(0).getReg()); - ++To; + MachineBasicBlock::iterator Begin = MI; + MachineBasicBlock::iterator AfterMI = llvm::next(Begin); + + MachineBasicBlock::iterator End = AfterMI; + while (End->isCopy() && Defs.count(End->getOperand(1).getReg())) { + Defs.insert(End->getOperand(0).getReg()); + ++End; } // Check if the reschedule will not break depedencies. unsigned NumVisited = 0; MachineBasicBlock::iterator KillPos = KillMI; ++KillPos; - for (MachineBasicBlock::iterator I = To; I != KillPos; ++I) { + for (MachineBasicBlock::iterator I = End; I != KillPos; ++I) { MachineInstr *OtherMI = I; // DBG_VALUE cannot be counted against the limit. if (OtherMI->isDebugValue()) @@ -803,11 +855,13 @@ rescheduleMIBelowKill(MachineBasicBlock::iterator &mi, } else { if (Defs.count(MOReg)) return false; + bool isKill = MO.isKill() || + (LIS && isPlainlyKilled(OtherMI, MOReg, LIS)); if (MOReg != Reg && - ((MO.isKill() && Uses.count(MOReg)) || Kills.count(MOReg))) + ((isKill && Uses.count(MOReg)) || Kills.count(MOReg))) // Don't want to extend other live ranges and update kills. return false; - if (MOReg == Reg && !MO.isKill()) + if (MOReg == Reg && !isKill) // We can't schedule across a use of the register in question. return false; // Ensure that if this is register in question, its the kill we expect. @@ -818,19 +872,35 @@ rescheduleMIBelowKill(MachineBasicBlock::iterator &mi, } // Move debug info as well. - while (From != MBB->begin() && llvm::prior(From)->isDebugValue()) - --From; + while (Begin != MBB->begin() && llvm::prior(Begin)->isDebugValue()) + --Begin; + + nmi = End; + MachineBasicBlock::iterator InsertPos = KillPos; + if (LIS) { + // We have to move the copies first so that the MBB is still well-formed + // when calling handleMove(). + for (MachineBasicBlock::iterator MBBI = AfterMI; MBBI != End;) { + MachineInstr *CopyMI = MBBI; + ++MBBI; + MBB->splice(InsertPos, MBB, CopyMI); + LIS->handleMove(CopyMI); + InsertPos = CopyMI; + } + End = llvm::next(MachineBasicBlock::iterator(MI)); + } // Copies following MI may have been moved as well. - nmi = To; - MBB->splice(KillPos, MBB, From, To); + MBB->splice(InsertPos, MBB, Begin, End); DistanceMap.erase(DI); // Update live variables - LV->removeVirtualRegisterKilled(Reg, KillMI); - LV->addVirtualRegisterKilled(Reg, MI); - if (LIS) + if (LIS) { LIS->handleMove(MI); + } else { + LV->removeVirtualRegisterKilled(Reg, KillMI); + LV->addVirtualRegisterKilled(Reg, MI); + } DEBUG(dbgs() << "\trescheduled below kill: " << *KillMI); return true; @@ -866,9 +936,9 @@ bool TwoAddressInstructionPass:: rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, MachineBasicBlock::iterator &nmi, unsigned Reg) { - // Bail immediately if we don't have LV available. We use it to find kills - // efficiently. - if (!LV) + // Bail immediately if we don't have LV or LIS available. We use them to find + // kills efficiently. + if (!LV && !LIS) return false; MachineInstr *MI = &*mi; @@ -877,7 +947,22 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, // Must be created from unfolded load. Don't waste time trying this. return false; - MachineInstr *KillMI = LV->getVarInfo(Reg).findKill(MBB); + MachineInstr *KillMI = 0; + if (LIS) { + LiveInterval &LI = LIS->getInterval(Reg); + assert(LI.end() != LI.begin() && + "Reg should not have empty live interval."); + + SlotIndex MBBEndIdx = LIS->getMBBEndIdx(MBB).getPrevSlot(); + LiveInterval::const_iterator I = LI.find(MBBEndIdx); + if (I != LI.end() && I->start < MBBEndIdx) + return false; + + --I; + KillMI = LIS->getInstructionFromIndex(I->end); + } else { + KillMI = LV->getVarInfo(Reg).findKill(MBB); + } if (!KillMI || MI == KillMI || KillMI->isCopy() || KillMI->isCopyLike()) // Don't mess with copies, they may be coalesced later. return false; @@ -904,10 +989,11 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, continue; if (isDefTooClose(MOReg, DI->second, MI)) return false; - if (MOReg == Reg && !MO.isKill()) + bool isKill = MO.isKill() || (LIS && isPlainlyKilled(KillMI, MOReg, LIS)); + if (MOReg == Reg && !isKill) return false; Uses.insert(MOReg); - if (MO.isKill() && MOReg != Reg) + if (isKill && MOReg != Reg) Kills.insert(MOReg); } else if (TargetRegisterInfo::isPhysicalRegister(MOReg)) { Defs.insert(MOReg); @@ -947,7 +1033,8 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, if (Kills.count(MOReg)) // Don't want to extend other live ranges and update kills. return false; - if (OtherMI != MI && MOReg == Reg && !MO.isKill()) + if (OtherMI != MI && MOReg == Reg && + !(MO.isKill() || (LIS && isPlainlyKilled(OtherMI, MOReg, LIS)))) // We can't schedule across a use of the register in question. return false; } else { @@ -981,10 +1068,12 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, DistanceMap.erase(DI); // Update live variables - LV->removeVirtualRegisterKilled(Reg, KillMI); - LV->addVirtualRegisterKilled(Reg, MI); - if (LIS) + if (LIS) { LIS->handleMove(KillMI); + } else { + LV->removeVirtualRegisterKilled(Reg, KillMI); + LV->addVirtualRegisterKilled(Reg, MI); + } DEBUG(dbgs() << "\trescheduled kill: " << *KillMI); return true; @@ -995,11 +1084,13 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi, /// either eliminate the tied operands or improve the opportunities for /// coalescing away the register copy. Returns true if no copy needs to be /// inserted to untie mi's operands (either because they were untied, or -/// because mi was rescheduled, and will be visited again later). +/// because mi was rescheduled, and will be visited again later). If the +/// shouldOnlyCommute flag is true, only instruction commutation is attempted. bool TwoAddressInstructionPass:: tryInstructionTransform(MachineBasicBlock::iterator &mi, MachineBasicBlock::iterator &nmi, - unsigned SrcIdx, unsigned DstIdx, unsigned Dist) { + unsigned SrcIdx, unsigned DstIdx, + unsigned Dist, bool shouldOnlyCommute) { if (OptLevel == CodeGenOpt::None) return false; @@ -1009,7 +1100,7 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, assert(TargetRegisterInfo::isVirtualRegister(regB) && "cannot make instruction into two-address form"); - bool regBKilled = isKilled(MI, regB, MRI, TII); + bool regBKilled = isKilled(MI, regB, MRI, TII, LIS, true); if (TargetRegisterInfo::isVirtualRegister(regA)) scanUses(regA); @@ -1029,7 +1120,7 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, if (regCIdx != ~0U) { regC = MI.getOperand(regCIdx).getReg(); - if (!regBKilled && isKilled(MI, regC, MRI, TII)) + if (!regBKilled && isKilled(MI, regC, MRI, TII, LIS, false)) // If C dies but B does not, swap the B and C operands. // This makes the live ranges of A and C joinable. TryCommute = true; @@ -1048,6 +1139,9 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, return false; } + if (shouldOnlyCommute) + return false; + // If there is one more use of regB later in the same MBB, consider // re-schedule this MI below it. if (rescheduleMIBelowKill(mi, nmi, regB)) { @@ -1123,10 +1217,12 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, unsigned NewDstIdx = NewMIs[1]->findRegisterDefOperandIdx(regA); unsigned NewSrcIdx = NewMIs[1]->findRegisterUseOperandIdx(regB); MachineBasicBlock::iterator NewMI = NewMIs[1]; - bool TransformSuccess = - tryInstructionTransform(NewMI, mi, NewSrcIdx, NewDstIdx, Dist); - if (TransformSuccess || - NewMIs[1]->getOperand(NewSrcIdx).isKill()) { + bool TransformResult = + tryInstructionTransform(NewMI, mi, NewSrcIdx, NewDstIdx, Dist, true); + (void)TransformResult; + assert(!TransformResult && + "tryInstructionTransform() should return false."); + if (NewMIs[1]->getOperand(NewSrcIdx).isKill()) { // Success, or at least we made an improvement. Keep the unfolded // instructions and discard the original. if (LV) { @@ -1157,10 +1253,26 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi, } LV->addVirtualRegisterKilled(Reg, NewMIs[1]); } + + SmallVector<unsigned, 4> OrigRegs; + if (LIS) { + for (MachineInstr::const_mop_iterator MOI = MI.operands_begin(), + MOE = MI.operands_end(); MOI != MOE; ++MOI) { + if (MOI->isReg()) + OrigRegs.push_back(MOI->getReg()); + } + } + MI.eraseFromParent(); + + // Update LiveIntervals. + if (LIS) { + MachineBasicBlock::iterator Begin(NewMIs[0]); + MachineBasicBlock::iterator End(NewMIs[1]); + LIS->repairIntervalsInRange(MBB, Begin, End, OrigRegs); + } + mi = NewMIs[1]; - if (TransformSuccess) - return true; } else { // Transforming didn't eliminate the tie and didn't lead to an // improvement. Clean up the unfolded instructions and keep the @@ -1223,9 +1335,15 @@ TwoAddressInstructionPass::processTiedPairs(MachineInstr *MI, TiedPairList &TiedPairs, unsigned &Dist) { bool IsEarlyClobber = false; + for (unsigned tpi = 0, tpe = TiedPairs.size(); tpi != tpe; ++tpi) { + const MachineOperand &DstMO = MI->getOperand(TiedPairs[tpi].second); + IsEarlyClobber |= DstMO.isEarlyClobber(); + } + bool RemovedKillFlag = false; bool AllUsesCopied = true; unsigned LastCopiedReg = 0; + SlotIndex LastCopyIdx; unsigned RegB = 0; for (unsigned tpi = 0, tpe = TiedPairs.size(); tpi != tpe; ++tpi) { unsigned SrcIdx = TiedPairs[tpi].first; @@ -1233,7 +1351,6 @@ TwoAddressInstructionPass::processTiedPairs(MachineInstr *MI, const MachineOperand &DstMO = MI->getOperand(DstIdx); unsigned RegA = DstMO.getReg(); - IsEarlyClobber |= DstMO.isEarlyClobber(); // Grab RegB from the instruction because it may have changed if the // instruction was commuted. @@ -1271,9 +1388,17 @@ TwoAddressInstructionPass::processTiedPairs(MachineInstr *MI, DistanceMap.insert(std::make_pair(PrevMI, Dist)); DistanceMap[MI] = ++Dist; - SlotIndex CopyIdx; - if (Indexes) - CopyIdx = Indexes->insertMachineInstrInMaps(PrevMI).getRegSlot(); + if (LIS) { + LastCopyIdx = LIS->InsertMachineInstrInMaps(PrevMI).getRegSlot(); + + if (TargetRegisterInfo::isVirtualRegister(RegA)) { + LiveInterval &LI = LIS->getInterval(RegA); + VNInfo *VNI = LI.getNextValue(LastCopyIdx, LIS->getVNInfoAllocator()); + SlotIndex endIdx = + LIS->getInstructionIndex(MI).getRegSlot(IsEarlyClobber); + LI.addRange(LiveRange(LastCopyIdx, endIdx, VNI)); + } + } DEBUG(dbgs() << "\t\tprepend:\t" << *PrevMI); @@ -1319,6 +1444,18 @@ TwoAddressInstructionPass::processTiedPairs(MachineInstr *MI, LV->addVirtualRegisterKilled(RegB, PrevMI); } + // Update LiveIntervals. + if (LIS) { + LiveInterval &LI = LIS->getInterval(RegB); + SlotIndex MIIdx = LIS->getInstructionIndex(MI); + LiveInterval::const_iterator I = LI.find(MIIdx); + assert(I != LI.end() && "RegB must be live-in to use."); + + SlotIndex UseIdx = MIIdx.getRegSlot(IsEarlyClobber); + if (I->end == UseIdx) + LI.removeRange(LastCopyIdx, UseIdx); + } + } else if (RemovedKillFlag) { // Some tied uses of regB matched their destination registers, so // regB is still used in this instruction, but a kill flag was @@ -1343,7 +1480,6 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { TII = TM.getInstrInfo(); TRI = TM.getRegisterInfo(); InstrItins = TM.getInstrItineraryData(); - Indexes = getAnalysisIfAvailable<SlotIndexes>(); LV = getAnalysisIfAvailable<LiveVariables>(); LIS = getAnalysisIfAvailable<LiveIntervals>(); AA = &getAnalysis<AliasAnalysis>(); @@ -1375,9 +1511,10 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { continue; } - // Remember REG_SEQUENCE instructions, we'll deal with them later. + // Expand REG_SEQUENCE instructions. This will position mi at the first + // expanded instruction. if (mi->isRegSequence()) - RegSequences.push_back(&*mi); + eliminateRegSequence(mi); DistanceMap.insert(std::make_pair(mi, ++Dist)); @@ -1406,7 +1543,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { unsigned SrcReg = mi->getOperand(SrcIdx).getReg(); unsigned DstReg = mi->getOperand(DstIdx).getReg(); if (SrcReg != DstReg && - tryInstructionTransform(mi, nmi, SrcIdx, DstIdx, Dist)) { + tryInstructionTransform(mi, nmi, SrcIdx, DstIdx, Dist, false)) { // The tied operands have been eliminated or shifted further down the // block to ease elimination. Continue processing with 'nmi'. TiedOperands.clear(); @@ -1444,192 +1581,98 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) { } } - // Eliminate REG_SEQUENCE instructions. Their whole purpose was to preseve - // SSA form. It's now safe to de-SSA. - MadeChange |= eliminateRegSequences(); + if (LIS) + MF->verify(this, "After two-address instruction pass"); return MadeChange; } -static void UpdateRegSequenceSrcs(unsigned SrcReg, - unsigned DstReg, unsigned SubIdx, - MachineRegisterInfo *MRI, - const TargetRegisterInfo &TRI) { - for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(SrcReg), - RE = MRI->reg_end(); RI != RE; ) { - MachineOperand &MO = RI.getOperand(); - ++RI; - MO.substVirtReg(DstReg, SubIdx, TRI); +/// Eliminate a REG_SEQUENCE instruction as part of the de-ssa process. +/// +/// The instruction is turned into a sequence of sub-register copies: +/// +/// %dst = REG_SEQUENCE %v1, ssub0, %v2, ssub1 +/// +/// Becomes: +/// +/// %dst:ssub0<def,undef> = COPY %v1 +/// %dst:ssub1<def> = COPY %v2 +/// +void TwoAddressInstructionPass:: +eliminateRegSequence(MachineBasicBlock::iterator &MBBI) { + MachineInstr *MI = MBBI; + unsigned DstReg = MI->getOperand(0).getReg(); + if (MI->getOperand(0).getSubReg() || + TargetRegisterInfo::isPhysicalRegister(DstReg) || + !(MI->getNumOperands() & 1)) { + DEBUG(dbgs() << "Illegal REG_SEQUENCE instruction:" << *MI); + llvm_unreachable(0); } -} - -// Find the first def of Reg, assuming they are all in the same basic block. -static MachineInstr *findFirstDef(unsigned Reg, MachineRegisterInfo *MRI) { - SmallPtrSet<MachineInstr*, 8> Defs; - MachineInstr *First = 0; - for (MachineRegisterInfo::def_iterator RI = MRI->def_begin(Reg); - MachineInstr *MI = RI.skipInstruction(); Defs.insert(MI)) - First = MI; - if (!First) - return 0; - - MachineBasicBlock *MBB = First->getParent(); - MachineBasicBlock::iterator A = First, B = First; - bool Moving; - do { - Moving = false; - if (A != MBB->begin()) { - Moving = true; - --A; - if (Defs.erase(A)) First = A; - } - if (B != MBB->end()) { - Defs.erase(B); - ++B; - Moving = true; - } - } while (Moving && !Defs.empty()); - assert(Defs.empty() && "Instructions outside basic block!"); - return First; -} -static bool HasOtherRegSequenceUses(unsigned Reg, MachineInstr *RegSeq, - MachineRegisterInfo *MRI) { - for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg), - UE = MRI->use_end(); UI != UE; ++UI) { - MachineInstr *UseMI = &*UI; - if (UseMI != RegSeq && UseMI->isRegSequence()) - return true; + SmallVector<unsigned, 4> OrigRegs; + if (LIS) { + OrigRegs.push_back(MI->getOperand(0).getReg()); + for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) + OrigRegs.push_back(MI->getOperand(i).getReg()); } - return false; -} -/// eliminateRegSequences - Eliminate REG_SEQUENCE instructions as part -/// of the de-ssa process. This replaces sources of REG_SEQUENCE as -/// sub-register references of the register defined by REG_SEQUENCE. e.g. -/// -/// %reg1029<def>, %reg1030<def> = VLD1q16 %reg1024<kill>, ... -/// %reg1031<def> = REG_SEQUENCE %reg1029<kill>, 5, %reg1030<kill>, 6 -/// => -/// %reg1031:5<def>, %reg1031:6<def> = VLD1q16 %reg1024<kill>, ... -bool TwoAddressInstructionPass::eliminateRegSequences() { - if (RegSequences.empty()) - return false; - - for (unsigned i = 0, e = RegSequences.size(); i != e; ++i) { - MachineInstr *MI = RegSequences[i]; - unsigned DstReg = MI->getOperand(0).getReg(); - if (MI->getOperand(0).getSubReg() || - TargetRegisterInfo::isPhysicalRegister(DstReg) || - !(MI->getNumOperands() & 1)) { - DEBUG(dbgs() << "Illegal REG_SEQUENCE instruction:" << *MI); - llvm_unreachable(0); - } - - bool IsImpDef = true; - SmallVector<unsigned, 4> RealSrcs; - SmallSet<unsigned, 4> Seen; - for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) { - // Nothing needs to be inserted for <undef> operands. - if (MI->getOperand(i).isUndef()) { - MI->getOperand(i).setReg(0); - continue; - } - unsigned SrcReg = MI->getOperand(i).getReg(); - unsigned SrcSubIdx = MI->getOperand(i).getSubReg(); - unsigned SubIdx = MI->getOperand(i+1).getImm(); - // DefMI of NULL means the value does not have a vreg in this block - // i.e., its a physical register or a subreg. - // In either case we force a copy to be generated. - MachineInstr *DefMI = NULL; - if (!MI->getOperand(i).getSubReg() && - !TargetRegisterInfo::isPhysicalRegister(SrcReg)) { - DefMI = MRI->getUniqueVRegDef(SrcReg); - } + bool DefEmitted = false; + for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) { + MachineOperand &UseMO = MI->getOperand(i); + unsigned SrcReg = UseMO.getReg(); + unsigned SubIdx = MI->getOperand(i+1).getImm(); + // Nothing needs to be inserted for <undef> operands. + if (UseMO.isUndef()) + continue; - if (DefMI && DefMI->isImplicitDef()) { - DefMI->eraseFromParent(); - continue; - } - IsImpDef = false; - - // Remember COPY sources. These might be candidate for coalescing. - if (DefMI && DefMI->isCopy() && DefMI->getOperand(1).getSubReg()) - RealSrcs.push_back(DefMI->getOperand(1).getReg()); - - bool isKill = MI->getOperand(i).isKill(); - if (!DefMI || !Seen.insert(SrcReg) || - MI->getParent() != DefMI->getParent() || - !isKill || HasOtherRegSequenceUses(SrcReg, MI, MRI) || - !TRI->getMatchingSuperRegClass(MRI->getRegClass(DstReg), - MRI->getRegClass(SrcReg), SubIdx)) { - // REG_SEQUENCE cannot have duplicated operands, add a copy. - // Also add an copy if the source is live-in the block. We don't want - // to end up with a partial-redef of a livein, e.g. - // BB0: - // reg1051:10<def> = - // ... - // BB1: - // ... = reg1051:10 - // BB2: - // reg1051:9<def> = - // LiveIntervalAnalysis won't like it. - // - // If the REG_SEQUENCE doesn't kill its source, keeping live variables - // correctly up to date becomes very difficult. Insert a copy. - - // Defer any kill flag to the last operand using SrcReg. Otherwise, we - // might insert a COPY that uses SrcReg after is was killed. - if (isKill) - for (unsigned j = i + 2; j < e; j += 2) - if (MI->getOperand(j).getReg() == SrcReg) { - MI->getOperand(j).setIsKill(); - isKill = false; - break; - } + // Defer any kill flag to the last operand using SrcReg. Otherwise, we + // might insert a COPY that uses SrcReg after is was killed. + bool isKill = UseMO.isKill(); + if (isKill) + for (unsigned j = i + 2; j < e; j += 2) + if (MI->getOperand(j).getReg() == SrcReg) { + MI->getOperand(j).setIsKill(); + UseMO.setIsKill(false); + isKill = false; + break; + } - MachineBasicBlock::iterator InsertLoc = MI; - MachineInstr *CopyMI = BuildMI(*MI->getParent(), InsertLoc, - MI->getDebugLoc(), TII->get(TargetOpcode::COPY)) - .addReg(DstReg, RegState::Define, SubIdx) - .addReg(SrcReg, getKillRegState(isKill), SrcSubIdx); - MI->getOperand(i).setReg(0); - if (LV && isKill && !TargetRegisterInfo::isPhysicalRegister(SrcReg)) - LV->replaceKillInstruction(SrcReg, MI, CopyMI); - DEBUG(dbgs() << "Inserted: " << *CopyMI); - } + // Insert the sub-register copy. + MachineInstr *CopyMI = BuildMI(*MI->getParent(), MI, MI->getDebugLoc(), + TII->get(TargetOpcode::COPY)) + .addReg(DstReg, RegState::Define, SubIdx) + .addOperand(UseMO); + + // The first def needs an <undef> flag because there is no live register + // before it. + if (!DefEmitted) { + CopyMI->getOperand(0).setIsUndef(true); + // Return an iterator pointing to the first inserted instr. + MBBI = CopyMI; } + DefEmitted = true; - for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) { - unsigned SrcReg = MI->getOperand(i).getReg(); - if (!SrcReg) continue; - unsigned SubIdx = MI->getOperand(i+1).getImm(); - UpdateRegSequenceSrcs(SrcReg, DstReg, SubIdx, MRI, *TRI); - } + // Update LiveVariables' kill info. + if (LV && isKill && !TargetRegisterInfo::isPhysicalRegister(SrcReg)) + LV->replaceKillInstruction(SrcReg, MI, CopyMI); - // Set <def,undef> flags on the first DstReg def in the basic block. - // It marks the beginning of the live range. All the other defs are - // read-modify-write. - if (MachineInstr *Def = findFirstDef(DstReg, MRI)) { - for (unsigned i = 0, e = Def->getNumOperands(); i != e; ++i) { - MachineOperand &MO = Def->getOperand(i); - if (MO.isReg() && MO.isDef() && MO.getReg() == DstReg) - MO.setIsUndef(); - } - DEBUG(dbgs() << "First def: " << *Def); - } + DEBUG(dbgs() << "Inserted: " << *CopyMI); + } - if (IsImpDef) { - DEBUG(dbgs() << "Turned: " << *MI << " into an IMPLICIT_DEF"); - MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF)); - for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j) - MI->RemoveOperand(j); - } else { - DEBUG(dbgs() << "Eliminated: " << *MI); - MI->eraseFromParent(); - } + MachineBasicBlock::iterator EndMBBI = + llvm::next(MachineBasicBlock::iterator(MI)); + + if (!DefEmitted) { + DEBUG(dbgs() << "Turned: " << *MI << " into an IMPLICIT_DEF"); + MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF)); + for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j) + MI->RemoveOperand(j); + } else { + DEBUG(dbgs() << "Eliminated: " << *MI); + MI->eraseFromParent(); } - RegSequences.clear(); - return true; + // Udpate LiveIntervals. + if (LIS) + LIS->repairIntervalsInRange(MBB, MBBI, EndMBBI, OrigRegs); } |
