#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/Target/TargetRegisterInfo.h"
MachineFunction::iterator &mbbi,
unsigned RegB, unsigned RegC, unsigned Dist);
- bool isProfitableToConv3Addr(unsigned RegA);
+ bool isProfitableToConv3Addr(unsigned RegA, unsigned RegB);
bool ConvertInstTo3Addr(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi,
- unsigned RegB, unsigned Dist);
+ unsigned RegA, unsigned RegB, unsigned Dist);
typedef std::pair<std::pair<unsigned, bool>, MachineInstr*> NewKill;
bool canUpdateDeletedKills(SmallVector<unsigned, 4> &Kills,
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi,
unsigned SrcIdx, unsigned DstIdx,
- unsigned Dist);
+ unsigned Dist,
+ SmallPtrSet<MachineInstr*, 8> &Processed);
+
+ void ScanUses(unsigned DstReg, MachineBasicBlock *MBB,
+ SmallPtrSet<MachineInstr*, 8> &Processed);
void ProcessCopy(MachineInstr *MI, MachineBasicBlock *MBB,
SmallPtrSet<MachineInstr*, 8> &Processed);
+ void CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs, unsigned DstReg);
+
/// 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();
+
public:
static char ID; // Pass identification, replacement for typeid
- TwoAddressInstructionPass() : MachineFunctionPass(&ID) {}
+ TwoAddressInstructionPass() : MachineFunctionPass(ID) {
+ initializeTwoAddressInstructionPassPass(*PassRegistry::getPassRegistry());
+ }
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
- if (StrongPHIElim)
- AU.addPreservedID(StrongPHIEliminationID);
- else
- AU.addPreservedID(PHIEliminationID);
+ AU.addPreservedID(PHIEliminationID);
MachineFunctionPass::getAnalysisUsage(AU);
}
}
char TwoAddressInstructionPass::ID = 0;
-static RegisterPass<TwoAddressInstructionPass>
-X("twoaddressinstruction", "Two-Address instruction pass");
+INITIALIZE_PASS_BEGIN(TwoAddressInstructionPass, "twoaddressinstruction",
+ "Two-Address instruction pass", false, false)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_END(TwoAddressInstructionPass, "twoaddressinstruction",
+ "Two-Address instruction pass", false, false)
-const PassInfo *const llvm::TwoAddressInstructionPassID = &X;
+char &llvm::TwoAddressInstructionPassID = TwoAddressInstructionPass::ID;
/// Sink3AddrInstruction - A two-address instruction has been converted to a
/// three-address instruction to avoid clobbering a register. Try to sink it
bool &IsSrcPhys, bool &IsDstPhys) {
SrcReg = 0;
DstReg = 0;
- unsigned SrcSubIdx, DstSubIdx;
- if (!TII->isMoveInstr(MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
- if (MI.isExtractSubreg()) {
- DstReg = MI.getOperand(0).getReg();
- SrcReg = MI.getOperand(1).getReg();
- } else if (MI.isInsertSubreg()) {
- DstReg = MI.getOperand(0).getReg();
- SrcReg = MI.getOperand(2).getReg();
- } else if (MI.isSubregToReg()) {
- DstReg = MI.getOperand(0).getReg();
- SrcReg = MI.getOperand(2).getReg();
- }
- }
+ if (MI.isCopy()) {
+ DstReg = MI.getOperand(0).getReg();
+ SrcReg = MI.getOperand(1).getReg();
+ } else if (MI.isInsertSubreg() || MI.isSubregToReg()) {
+ DstReg = MI.getOperand(0).getReg();
+ SrcReg = MI.getOperand(2).getReg();
+ } else
+ return false;
- if (DstReg) {
- IsSrcPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
- IsDstPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
- return true;
- }
- return false;
+ IsSrcPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
+ IsDstPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
+ return true;
}
/// isKilled - Test if the given register value, which is used by the given
unsigned FromRegC = getMappedReg(regC, SrcRegMap);
unsigned ToRegB = getMappedReg(regB, DstRegMap);
unsigned ToRegC = getMappedReg(regC, DstRegMap);
- if (!regsAreCompatible(FromRegB, ToRegB, TRI) &&
- (regsAreCompatible(FromRegB, ToRegC, TRI) ||
+ if ((FromRegB && ToRegB && !regsAreCompatible(FromRegB, ToRegB, TRI)) &&
+ ((!FromRegC && !ToRegC) ||
+ regsAreCompatible(FromRegB, ToRegC, TRI) ||
regsAreCompatible(FromRegC, ToRegB, TRI)))
return true;
/// isProfitableToConv3Addr - Return true if it is profitable to convert the
/// given 2-address instruction to a 3-address one.
bool
-TwoAddressInstructionPass::isProfitableToConv3Addr(unsigned RegA) {
+TwoAddressInstructionPass::isProfitableToConv3Addr(unsigned RegA,unsigned RegB){
// Look for situations like this:
// %reg1024<def> = MOV r1
// %reg1025<def> = MOV r0
// %reg1026<def> = ADD %reg1024, %reg1025
// r2 = MOV %reg1026
// Turn ADD into a 3-address instruction to avoid a copy.
- unsigned FromRegA = getMappedReg(RegA, SrcRegMap);
+ unsigned FromRegB = getMappedReg(RegB, SrcRegMap);
+ if (!FromRegB)
+ return false;
unsigned ToRegA = getMappedReg(RegA, DstRegMap);
- return (FromRegA && ToRegA && !regsAreCompatible(FromRegA, ToRegA, TRI));
+ return (ToRegA && !regsAreCompatible(FromRegB, ToRegA, TRI));
}
/// ConvertInstTo3Addr - Convert the specified two-address instruction into a
TwoAddressInstructionPass::ConvertInstTo3Addr(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi,
- unsigned RegB, unsigned Dist) {
+ unsigned RegA, unsigned RegB,
+ unsigned Dist) {
MachineInstr *NewMI = TII->convertToThreeAddress(mbbi, mi, LV);
if (NewMI) {
DEBUG(dbgs() << "2addr: CONVERTING 2-ADDR: " << *mi);
mi = NewMI;
nmi = llvm::next(mi);
}
+
+ // Update source and destination register maps.
+ SrcRegMap.erase(RegA);
+ DstRegMap.erase(RegB);
return true;
}
return false;
}
+/// ScanUses - Scan forward recursively for only uses, update maps if the use
+/// is a copy or a two-address instruction.
+void
+TwoAddressInstructionPass::ScanUses(unsigned DstReg, MachineBasicBlock *MBB,
+ SmallPtrSet<MachineInstr*, 8> &Processed) {
+ SmallVector<unsigned, 4> VirtRegPairs;
+ bool IsDstPhys;
+ bool IsCopy = false;
+ unsigned NewReg = 0;
+ unsigned Reg = DstReg;
+ while (MachineInstr *UseMI = findOnlyInterestingUse(Reg, MBB, MRI, TII,IsCopy,
+ NewReg, IsDstPhys)) {
+ if (IsCopy && !Processed.insert(UseMI))
+ break;
+
+ DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
+ if (DI != DistanceMap.end())
+ // Earlier in the same MBB.Reached via a back edge.
+ break;
+
+ if (IsDstPhys) {
+ VirtRegPairs.push_back(NewReg);
+ break;
+ }
+ bool isNew = SrcRegMap.insert(std::make_pair(NewReg, Reg)).second;
+ if (!isNew)
+ assert(SrcRegMap[NewReg] == Reg && "Can't map to two src registers!");
+ VirtRegPairs.push_back(NewReg);
+ Reg = NewReg;
+ }
+
+ if (!VirtRegPairs.empty()) {
+ unsigned ToReg = VirtRegPairs.back();
+ VirtRegPairs.pop_back();
+ while (!VirtRegPairs.empty()) {
+ unsigned FromReg = VirtRegPairs.back();
+ VirtRegPairs.pop_back();
+ bool isNew = DstRegMap.insert(std::make_pair(FromReg, ToReg)).second;
+ if (!isNew)
+ assert(DstRegMap[FromReg] == ToReg &&"Can't map to two dst registers!");
+ ToReg = FromReg;
+ }
+ bool isNew = DstRegMap.insert(std::make_pair(DstReg, ToReg)).second;
+ if (!isNew)
+ assert(DstRegMap[DstReg] == ToReg && "Can't map to two dst registers!");
+ }
+}
+
/// ProcessCopy - If the specified instruction is not yet processed, process it
/// if it's a copy. For a copy instruction, we find the physical registers the
/// source and destination registers might be mapped to. These are kept in
assert(SrcRegMap[DstReg] == SrcReg &&
"Can't map to two src physical registers!");
- SmallVector<unsigned, 4> VirtRegPairs;
- bool IsCopy = false;
- unsigned NewReg = 0;
- while (MachineInstr *UseMI = findOnlyInterestingUse(DstReg, MBB, MRI,TII,
- IsCopy, NewReg, IsDstPhys)) {
- if (IsCopy) {
- if (!Processed.insert(UseMI))
- break;
- }
-
- DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
- if (DI != DistanceMap.end())
- // Earlier in the same MBB.Reached via a back edge.
- break;
-
- if (IsDstPhys) {
- VirtRegPairs.push_back(NewReg);
- break;
- }
- bool isNew = SrcRegMap.insert(std::make_pair(NewReg, DstReg)).second;
- if (!isNew)
- assert(SrcRegMap[NewReg] == DstReg &&
- "Can't map to two src physical registers!");
- VirtRegPairs.push_back(NewReg);
- DstReg = NewReg;
- }
-
- if (!VirtRegPairs.empty()) {
- unsigned ToReg = VirtRegPairs.back();
- VirtRegPairs.pop_back();
- while (!VirtRegPairs.empty()) {
- unsigned FromReg = VirtRegPairs.back();
- VirtRegPairs.pop_back();
- bool isNew = DstRegMap.insert(std::make_pair(FromReg, ToReg)).second;
- if (!isNew)
- assert(DstRegMap[FromReg] == ToReg &&
- "Can't map to two dst physical registers!");
- ToReg = FromReg;
- }
- }
+ ScanUses(DstReg, MBB, Processed);
}
Processed.insert(MI);
+ return;
}
/// isSafeToDelete - If the specified instruction does not produce any side
const TargetInstrDesc &TID = MI->getDesc();
if (TID.mayStore() || TID.isCall())
return false;
- if (TID.isTerminator() || TID.hasUnmodeledSideEffects())
+ if (TID.isTerminator() || MI->hasUnmodeledSideEffects())
return false;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
if (!LastKill)
return false;
- bool isModRef = LastKill->modifiesRegister(Kill);
+ bool isModRef = LastKill->definesRegister(Kill);
NewKills.push_back(std::make_pair(std::make_pair(Kill, isModRef),
LastKill));
}
TryInstructionTransform(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi,
- unsigned SrcIdx, unsigned DstIdx, unsigned Dist) {
+ unsigned SrcIdx, unsigned DstIdx, unsigned Dist,
+ SmallPtrSet<MachineInstr*, 8> &Processed) {
const TargetInstrDesc &TID = mi->getDesc();
unsigned regA = mi->getOperand(DstIdx).getReg();
unsigned regB = mi->getOperand(SrcIdx).getReg();
return false;
}
+ if (TargetRegisterInfo::isVirtualRegister(regA))
+ ScanUses(regA, &*mbbi, Processed);
+
if (TID.isConvertibleTo3Addr()) {
// This instruction is potentially convertible to a true
// three-address instruction. Check if it is profitable.
- if (!regBKilled || isProfitableToConv3Addr(regA)) {
+ if (!regBKilled || isProfitableToConv3Addr(regA, regB)) {
// Try to convert it.
- if (ConvertInstTo3Addr(mi, nmi, mbbi, regB, Dist)) {
+ if (ConvertInstTo3Addr(mi, nmi, mbbi, regA, regB, Dist)) {
++NumConvertedTo3Addr;
return true; // Done with this instruction.
}
}
}
+
+ // If this is an instruction with a load folded into it, try unfolding
+ // the load, e.g. avoid this:
+ // movq %rdx, %rcx
+ // addq (%rax), %rcx
+ // in favor of this:
+ // movq (%rax), %rcx
+ // addq %rdx, %rcx
+ // because it's preferable to schedule a load than a register copy.
+ if (TID.mayLoad() && !regBKilled) {
+ // Determine if a load can be unfolded.
+ unsigned LoadRegIndex;
+ unsigned NewOpc =
+ TII->getOpcodeAfterMemoryUnfold(mi->getOpcode(),
+ /*UnfoldLoad=*/true,
+ /*UnfoldStore=*/false,
+ &LoadRegIndex);
+ if (NewOpc != 0) {
+ const TargetInstrDesc &UnfoldTID = TII->get(NewOpc);
+ if (UnfoldTID.getNumDefs() == 1) {
+ MachineFunction &MF = *mbbi->getParent();
+
+ // Unfold the load.
+ DEBUG(dbgs() << "2addr: UNFOLDING: " << *mi);
+ const TargetRegisterClass *RC =
+ UnfoldTID.OpInfo[LoadRegIndex].getRegClass(TRI);
+ unsigned Reg = MRI->createVirtualRegister(RC);
+ SmallVector<MachineInstr *, 2> NewMIs;
+ if (!TII->unfoldMemoryOperand(MF, mi, Reg,
+ /*UnfoldLoad=*/true,/*UnfoldStore=*/false,
+ NewMIs)) {
+ DEBUG(dbgs() << "2addr: ABANDONING UNFOLD\n");
+ return false;
+ }
+ assert(NewMIs.size() == 2 &&
+ "Unfolded a load into multiple instructions!");
+ // The load was previously folded, so this is the only use.
+ NewMIs[1]->addRegisterKilled(Reg, TRI);
+
+ // Tentatively insert the instructions into the block so that they
+ // look "normal" to the transformation logic.
+ mbbi->insert(mi, NewMIs[0]);
+ mbbi->insert(mi, NewMIs[1]);
+
+ DEBUG(dbgs() << "2addr: NEW LOAD: " << *NewMIs[0]
+ << "2addr: NEW INST: " << *NewMIs[1]);
+
+ // Transform the instruction, now that it no longer has a load.
+ unsigned NewDstIdx = NewMIs[1]->findRegisterDefOperandIdx(regA);
+ unsigned NewSrcIdx = NewMIs[1]->findRegisterUseOperandIdx(regB);
+ MachineBasicBlock::iterator NewMI = NewMIs[1];
+ bool TransformSuccess =
+ TryInstructionTransform(NewMI, mi, mbbi,
+ NewSrcIdx, NewDstIdx, Dist, Processed);
+ if (TransformSuccess ||
+ NewMIs[1]->getOperand(NewSrcIdx).isKill()) {
+ // Success, or at least we made an improvement. Keep the unfolded
+ // instructions and discard the original.
+ if (LV) {
+ for (unsigned i = 0, e = mi->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = mi->getOperand(i);
+ if (MO.isReg() &&
+ TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
+ if (MO.isUse()) {
+ if (MO.isKill()) {
+ if (NewMIs[0]->killsRegister(MO.getReg()))
+ LV->replaceKillInstruction(MO.getReg(), mi, NewMIs[0]);
+ else {
+ assert(NewMIs[1]->killsRegister(MO.getReg()) &&
+ "Kill missing after load unfold!");
+ LV->replaceKillInstruction(MO.getReg(), mi, NewMIs[1]);
+ }
+ }
+ } else if (LV->removeVirtualRegisterDead(MO.getReg(), mi)) {
+ if (NewMIs[1]->registerDefIsDead(MO.getReg()))
+ LV->addVirtualRegisterDead(MO.getReg(), NewMIs[1]);
+ else {
+ assert(NewMIs[0]->registerDefIsDead(MO.getReg()) &&
+ "Dead flag missing after load unfold!");
+ LV->addVirtualRegisterDead(MO.getReg(), NewMIs[0]);
+ }
+ }
+ }
+ }
+ LV->addVirtualRegisterKilled(Reg, NewMIs[1]);
+ }
+ mi->eraseFromParent();
+ 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
+ // original.
+ DEBUG(dbgs() << "2addr: ABANDONING UNFOLD\n");
+ NewMIs[0]->eraseFromParent();
+ NewMIs[1]->eraseFromParent();
+ }
+ }
+ }
+ }
+
return false;
}
<< MF.getFunction()->getName() << '\n');
// ReMatRegs - Keep track of the registers whose def's are remat'ed.
- BitVector ReMatRegs;
- ReMatRegs.resize(MRI->getLastVirtReg()+1);
+ BitVector ReMatRegs(MRI->getNumVirtRegs());
typedef DenseMap<unsigned, SmallVector<std::pair<unsigned, unsigned>, 4> >
TiedOperandMap;
mi->getOperand(DstIdx).getReg())
break; // Done with this instruction.
- if (TryInstructionTransform(mi, nmi, mbbi, SrcIdx, DstIdx, Dist))
+ if (TryInstructionTransform(mi, nmi, mbbi, SrcIdx, DstIdx, Dist,
+ Processed))
break; // The tied operands have been eliminated.
}
isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist)){
DEBUG(dbgs() << "2addr: REMATTING : " << *DefMI << "\n");
unsigned regASubIdx = mi->getOperand(DstIdx).getSubReg();
- TII->reMaterialize(*mbbi, mi, regA, regASubIdx, DefMI, TRI);
- ReMatRegs.set(regB);
+ TII->reMaterialize(*mbbi, mi, regA, regASubIdx, DefMI, *TRI);
+ ReMatRegs.set(TargetRegisterInfo::virtReg2Index(regB));
++NumReMats;
} else {
- bool Emitted = TII->copyRegToReg(*mbbi, mi, regA, regB, rc, rc,
- mi->getDebugLoc());
- (void)Emitted;
- assert(Emitted && "Unable to issue a copy instruction!\n");
+ BuildMI(*mbbi, mi, mi->getDebugLoc(), TII->get(TargetOpcode::COPY),
+ regA).addReg(regB);
}
MachineBasicBlock::iterator prevMI = prior(mi);
}
}
}
-
+
+ // Schedule the source copy / remat inserted to form two-address
+ // instruction. FIXME: Does it matter the distance map may not be
+ // accurate after it's scheduled?
+ TII->scheduleTwoAddrSource(prior(mi), mi, *TRI);
+
MadeChange = true;
DEBUG(dbgs() << "\t\trewrite to:\t" << *mi);
}
+ // Rewrite INSERT_SUBREG as COPY now that we no longer need SSA form.
+ if (mi->isInsertSubreg()) {
+ // From %reg = INSERT_SUBREG %reg, %subreg, subidx
+ // To %reg:subidx = COPY %subreg
+ unsigned SubIdx = mi->getOperand(3).getImm();
+ mi->RemoveOperand(3);
+ assert(mi->getOperand(0).getSubReg() == 0 && "Unexpected subreg idx");
+ mi->getOperand(0).setSubReg(SubIdx);
+ mi->RemoveOperand(1);
+ mi->setDesc(TII->get(TargetOpcode::COPY));
+ DEBUG(dbgs() << "\t\tconvert to:\t" << *mi);
+ }
+
// Clear TiedOperands here instead of at the top of the loop
// since most instructions do not have tied operands.
TiedOperands.clear();
}
// Some remat'ed instructions are dead.
- int VReg = ReMatRegs.find_first();
- while (VReg != -1) {
+ for (int i = ReMatRegs.find_first(); i != -1; i = ReMatRegs.find_next(i)) {
+ unsigned VReg = TargetRegisterInfo::index2VirtReg(i);
if (MRI->use_nodbg_empty(VReg)) {
MachineInstr *DefMI = MRI->getVRegDef(VReg);
DefMI->eraseFromParent();
}
- VReg = ReMatRegs.find_next(VReg);
}
// Eliminate REG_SEQUENCE instructions. Their whole purpose was to preseve
}
static void UpdateRegSequenceSrcs(unsigned SrcReg,
- unsigned DstReg, unsigned SrcIdx,
- MachineRegisterInfo *MRI) {
+ unsigned DstReg, unsigned SubIdx,
+ MachineRegisterInfo *MRI,
+ const TargetRegisterInfo &TRI) {
for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(SrcReg),
- UE = MRI->reg_end(); RI != UE; ) {
+ RE = MRI->reg_end(); RI != RE; ) {
MachineOperand &MO = RI.getOperand();
++RI;
- MO.setReg(DstReg);
- MO.setSubReg(SrcIdx);
+ MO.substVirtReg(DstReg, SubIdx, TRI);
}
}
+/// CoalesceExtSubRegs - If a number of sources of the REG_SEQUENCE are
+/// EXTRACT_SUBREG from the same register and to the same virtual register
+/// with different sub-register indices, attempt to combine the
+/// EXTRACT_SUBREGs and pre-coalesce them. e.g.
+/// %reg1026<def> = VLDMQ %reg1025<kill>, 260, pred:14, pred:%reg0
+/// %reg1029:6<def> = EXTRACT_SUBREG %reg1026, 6
+/// %reg1029:5<def> = EXTRACT_SUBREG %reg1026<kill>, 5
+/// Since D subregs 5, 6 can combine to a Q register, we can coalesce
+/// reg1026 to reg1029.
+void
+TwoAddressInstructionPass::CoalesceExtSubRegs(SmallVector<unsigned,4> &Srcs,
+ unsigned DstReg) {
+ SmallSet<unsigned, 4> Seen;
+ for (unsigned i = 0, e = Srcs.size(); i != e; ++i) {
+ unsigned SrcReg = Srcs[i];
+ if (!Seen.insert(SrcReg))
+ continue;
+
+ // Check that the instructions are all in the same basic block.
+ MachineInstr *SrcDefMI = MRI->getVRegDef(SrcReg);
+ MachineInstr *DstDefMI = MRI->getVRegDef(DstReg);
+ if (SrcDefMI->getParent() != DstDefMI->getParent())
+ continue;
+
+ // If there are no other uses than copies which feed into
+ // the reg_sequence, then we might be able to coalesce them.
+ bool CanCoalesce = true;
+ SmallVector<unsigned, 4> SrcSubIndices, DstSubIndices;
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI->use_nodbg_begin(SrcReg),
+ UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
+ MachineInstr *UseMI = &*UI;
+ if (!UseMI->isCopy() || UseMI->getOperand(0).getReg() != DstReg) {
+ CanCoalesce = false;
+ break;
+ }
+ SrcSubIndices.push_back(UseMI->getOperand(1).getSubReg());
+ DstSubIndices.push_back(UseMI->getOperand(0).getSubReg());
+ }
+
+ if (!CanCoalesce || SrcSubIndices.size() < 2)
+ continue;
+
+ // Check that the source subregisters can be combined.
+ std::sort(SrcSubIndices.begin(), SrcSubIndices.end());
+ unsigned NewSrcSubIdx = 0;
+ if (!TRI->canCombineSubRegIndices(MRI->getRegClass(SrcReg), SrcSubIndices,
+ NewSrcSubIdx))
+ continue;
+
+ // Check that the destination subregisters can also be combined.
+ std::sort(DstSubIndices.begin(), DstSubIndices.end());
+ unsigned NewDstSubIdx = 0;
+ if (!TRI->canCombineSubRegIndices(MRI->getRegClass(DstReg), DstSubIndices,
+ NewDstSubIdx))
+ continue;
+
+ // If neither source nor destination can be combined to the full register,
+ // just give up. This could be improved if it ever matters.
+ if (NewSrcSubIdx != 0 && NewDstSubIdx != 0)
+ continue;
+
+ // Now that we know that all the uses are extract_subregs and that those
+ // subregs can somehow be combined, scan all the extract_subregs again to
+ // make sure the subregs are in the right order and can be composed.
+ MachineInstr *SomeMI = 0;
+ CanCoalesce = true;
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI->use_nodbg_begin(SrcReg),
+ UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
+ MachineInstr *UseMI = &*UI;
+ assert(UseMI->isCopy());
+ unsigned DstSubIdx = UseMI->getOperand(0).getSubReg();
+ unsigned SrcSubIdx = UseMI->getOperand(1).getSubReg();
+ assert(DstSubIdx != 0 && "missing subreg from RegSequence elimination");
+ if ((NewDstSubIdx == 0 &&
+ TRI->composeSubRegIndices(NewSrcSubIdx, DstSubIdx) != SrcSubIdx) ||
+ (NewSrcSubIdx == 0 &&
+ TRI->composeSubRegIndices(NewDstSubIdx, SrcSubIdx) != DstSubIdx)) {
+ CanCoalesce = false;
+ break;
+ }
+ // Keep track of one of the uses.
+ SomeMI = UseMI;
+ }
+ if (!CanCoalesce)
+ continue;
+
+ // Insert a copy to replace the original.
+ MachineInstr *CopyMI = BuildMI(*SomeMI->getParent(), SomeMI,
+ SomeMI->getDebugLoc(),
+ TII->get(TargetOpcode::COPY))
+ .addReg(DstReg, RegState::Define, NewDstSubIdx)
+ .addReg(SrcReg, 0, NewSrcSubIdx);
+
+ // Remove all the old extract instructions.
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI->use_nodbg_begin(SrcReg),
+ UE = MRI->use_nodbg_end(); UI != UE; ) {
+ MachineInstr *UseMI = &*UI;
+ ++UI;
+ if (UseMI == CopyMI)
+ continue;
+ assert(UseMI->isCopy());
+ // Move any kills to the new copy or extract instruction.
+ if (UseMI->getOperand(1).isKill()) {
+ CopyMI->getOperand(1).setIsKill();
+ if (LV)
+ // Update live variables
+ LV->replaceKillInstruction(SrcReg, UseMI, &*CopyMI);
+ }
+ UseMI->eraseFromParent();
+ }
+ }
+}
+
+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;
+ }
+ 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.
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) {
unsigned SrcReg = MI->getOperand(i).getReg();
+ unsigned SubIdx = MI->getOperand(i+1).getImm();
if (MI->getOperand(i).getSubReg() ||
TargetRegisterInfo::isPhysicalRegister(SrcReg)) {
DEBUG(dbgs() << "Illegal REG_SEQUENCE instruction:" << *MI);
llvm_unreachable(0);
}
- unsigned SrcIdx = MI->getOperand(i+1).getImm();
- UpdateRegSequenceSrcs(SrcReg, DstReg, SrcIdx, MRI);
+
+ MachineInstr *DefMI = MRI->getVRegDef(SrcReg);
+ if (DefMI->isImplicitDef()) {
+ DefMI->eraseFromParent();
+ continue;
+ }
+ IsImpDef = false;
+
+ // Remember COPY sources. These might be candidate for coalescing.
+ if (DefMI->isCopy() && DefMI->getOperand(1).getSubReg())
+ RealSrcs.push_back(DefMI->getOperand(1).getReg());
+
+ bool isKill = MI->getOperand(i).isKill();
+ if (!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;
+ }
+
+ 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));
+ MI->getOperand(i).setReg(0);
+ if (LV && isKill)
+ LV->replaceKillInstruction(SrcReg, MI, CopyMI);
+ DEBUG(dbgs() << "Inserted: " << *CopyMI);
+ }
+ }
+
+ 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);
}
- DEBUG(dbgs() << "Eliminated: " << *MI);
- MI->eraseFromParent();
+ 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();
+ }
+
+ // Try coalescing some EXTRACT_SUBREG instructions. This can create
+ // INSERT_SUBREG instructions that must have <undef> flags added by
+ // LiveIntervalAnalysis, so only run it when LiveVariables is available.
+ if (LV)
+ CoalesceExtSubRegs(RealSrcs, DstReg);
}
RegSequences.clear();
projects / oota-llvm.git / blobdiff