MachineRegisterInfo *MRI;
LiveVariables *LV;
AliasAnalysis *AA;
+ CodeGenOpt::Level OptLevel;
// DistanceMap - Keep track the distance of a MI from the start of the
// current basic block.
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
- AU.addPreservedID(PHIEliminationID);
MachineFunctionPass::getAnalysisUsage(AU);
}
// appropriate location, we can try to sink the current instruction
// past it.
if (!KillMI || KillMI->getParent() != MBB || KillMI == MI ||
- KillMI->getDesc().isTerminator())
+ KillMI->isTerminator())
return false;
// If any of the definitions are used by another instruction between the
// position and the kill use, then it's not safe to sink it.
- //
+ //
// FIXME: This can be sped up if there is an easy way to query whether an
// instruction is before or after another instruction. Then we can use
// MachineRegisterInfo def / use instead.
KillMO->setIsKill(false);
KillMO = MI->findRegisterUseOperand(SavedReg, false, TRI);
KillMO->setIsKill(true);
-
+
if (LV)
LV->replaceKillInstruction(SavedReg, KillMI, MI);
continue; // Current use.
OtherUse = true;
// There is at least one other use in the MBB that will clobber the
- // register.
+ // register.
if (isTwoAddrUse(UseMI, Reg))
return true;
}
MachineInstr *UseMI = &*UI;
if (UseMI == MI || UseMI->getParent() != MBB)
continue;
- DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UseMI);
- if (DI != DistanceMap.end())
+ if (DistanceMap.count(UseMI))
continue;
if (!UI.getOperand().isKill())
return 0;
TwoAddressInstructionPass::isProfitableToCommute(unsigned regB, unsigned regC,
MachineInstr *MI, MachineBasicBlock *MBB,
unsigned Dist) {
+ if (OptLevel == CodeGenOpt::None)
+ return false;
+
// Determine if it's profitable to commute this two address instruction. In
// general, we want no uses between this instruction and the definition of
// the two-address register.
// %reg1029<def> = MOV8rr %reg1028
// %reg1029<def> = SHR8ri %reg1029, 7, %EFLAGS<imp-def,dead>
// insert => %reg1030<def> = MOV8rr %reg1029
- // %reg1030<def> = ADD8rr %reg1029<kill>, %reg1028<kill>, %EFLAGS<imp-def,dead>
+ // %reg1030<def> = ADD8rr %reg1029<kill>, %reg1028<kill>, %EFLAGS<imp-def,dead>
if (!MI->killsRegister(regC))
return false;
static bool isSafeToDelete(MachineInstr *MI,
const TargetInstrInfo *TII,
SmallVector<unsigned, 4> &Kills) {
- const MCInstrDesc &MCID = MI->getDesc();
- if (MCID.mayStore() || MCID.isCall())
+ if (MI->mayStore() || MI->isCall())
return false;
- if (MCID.isTerminator() || MI->hasUnmodeledSideEffects())
+ if (MI->isTerminator() || MI->hasUnmodeledSideEffects())
return false;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineBasicBlock::iterator &nmi,
unsigned Reg) {
MachineInstr *MI = &*mi;
- DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
+ DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
if (DI == DistanceMap.end())
// Must be created from unfolded load. Don't waste time trying this.
return false;
// Don't mess with copies, they may be coalesced later.
return false;
- const MCInstrDesc &MCID = KillMI->getDesc();
- if (MCID.hasUnmodeledSideEffects() || MCID.isCall() || MCID.isBranch() ||
- MCID.isTerminator())
+ if (KillMI->hasUnmodeledSideEffects() || KillMI->isCall() ||
+ KillMI->isBranch() || KillMI->isTerminator())
// Don't move pass calls, etc.
return false;
return false;
SmallSet<unsigned, 2> Uses;
+ SmallSet<unsigned, 2> Kills;
SmallSet<unsigned, 2> Defs;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
continue;
if (MO.isDef())
Defs.insert(MOReg);
- else
+ else {
Uses.insert(MOReg);
+ if (MO.isKill() && MOReg != Reg)
+ Kills.insert(MOReg);
+ }
}
// Move the copies connected to MI down as well.
if (NumVisited > 10) // FIXME: Arbitrary limit to reduce compile time cost.
return false;
++NumVisited;
- const MCInstrDesc &OMCID = OtherMI->getDesc();
- if (OMCID.hasUnmodeledSideEffects() || OMCID.isCall() || OMCID.isBranch() ||
- OMCID.isTerminator())
+ if (OtherMI->hasUnmodeledSideEffects() || OtherMI->isCall() ||
+ OtherMI->isBranch() || OtherMI->isTerminator())
// Don't move pass calls, etc.
return false;
for (unsigned i = 0, e = OtherMI->getNumOperands(); i != e; ++i) {
} else {
if (Defs.count(MOReg))
return false;
- if (MOReg != Reg && MO.isKill() && Uses.count(MOReg))
+ if (MOReg != Reg &&
+ ((MO.isKill() && Uses.count(MOReg)) || Kills.count(MOReg)))
// Don't want to extend other live ranges and update kills.
return false;
}
if (NumVisited > 10) // FIXME: Arbitrary limit to reduce compile time cost.
return false;
++NumVisited;
- const MCInstrDesc &MCID = OtherMI->getDesc();
- if (MCID.hasUnmodeledSideEffects() || MCID.isCall() || MCID.isBranch() ||
- MCID.isTerminator())
+ if (OtherMI->hasUnmodeledSideEffects() || OtherMI->isCall() ||
+ OtherMI->isBranch() || OtherMI->isTerminator())
// Don't move pass calls, etc.
return false;
+ SmallVector<unsigned, 2> OtherDefs;
for (unsigned i = 0, e = OtherMI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = OtherMI->getOperand(i);
if (!MO.isReg())
// Don't want to extend other live ranges and update kills.
return false;
} else {
- if (Uses.count(MOReg))
- return false;
- if (TargetRegisterInfo::isPhysicalRegister(MOReg) &&
- LiveDefs.count(MOReg))
- return false;
- // Physical register def is seen.
- Defs.erase(MOReg);
+ OtherDefs.push_back(MOReg);
}
}
+
+ for (unsigned i = 0, e = OtherDefs.size(); i != e; ++i) {
+ unsigned MOReg = OtherDefs[i];
+ if (Uses.count(MOReg))
+ return false;
+ if (TargetRegisterInfo::isPhysicalRegister(MOReg) &&
+ LiveDefs.count(MOReg))
+ return false;
+ // Physical register def is seen.
+ Defs.erase(MOReg);
+ }
}
// Move the old kill above MI, don't forget to move debug info as well.
--From;
MBB->splice(InsertPos, MBB, From, To);
- nmi = llvm::prior(mi); // Backtrack so we process the moved instruction.
+ nmi = llvm::prior(InsertPos); // Backtrack so we process the moved instr.
DistanceMap.erase(DI);
if (LV) {
/// TryInstructionTransform - For the case where an instruction has a single
/// pair of tied register operands, attempt some transformations that may
/// either eliminate the tied operands or improve the opportunities for
-/// coalescing away the register copy. Returns true if the tied operands
-/// are eliminated altogether.
+/// 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).
bool TwoAddressInstructionPass::
TryInstructionTransform(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi,
unsigned SrcIdx, unsigned DstIdx, unsigned Dist,
SmallPtrSet<MachineInstr*, 8> &Processed) {
+ if (OptLevel == CodeGenOpt::None)
+ return false;
+
MachineInstr &MI = *mi;
- const MCInstrDesc &MCID = MI.getDesc();
unsigned regA = MI.getOperand(DstIdx).getReg();
unsigned regB = MI.getOperand(SrcIdx).getReg();
unsigned regCIdx = ~0U;
bool TryCommute = false;
bool AggressiveCommute = false;
- if (MCID.isCommutable() && MI.getNumOperands() >= 3 &&
+ if (MI.isCommutable() && MI.getNumOperands() >= 3 &&
TII->findCommutedOpIndices(&MI, SrcOp1, SrcOp2)) {
if (SrcIdx == SrcOp1)
regCIdx = SrcOp2;
if (TargetRegisterInfo::isVirtualRegister(regA))
ScanUses(regA, &*mbbi, Processed);
- if (MCID.isConvertibleTo3Addr()) {
+ if (MI.isConvertibleTo3Addr()) {
// This instruction is potentially convertible to a true
// three-address instruction. Check if it is profitable.
if (!regBKilled || isProfitableToConv3Addr(regA, regB)) {
// movq (%rax), %rcx
// addq %rdx, %rcx
// because it's preferable to schedule a load than a register copy.
- if (MCID.mayLoad() && !regBKilled) {
+ if (MI.mayLoad() && !regBKilled) {
// Determine if a load can be unfolded.
unsigned LoadRegIndex;
unsigned NewOpc =
if (LV) {
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI.getOperand(i);
- if (MO.isReg() &&
+ if (MO.isReg() &&
TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
if (MO.isUse()) {
if (MO.isKill()) {
/// runOnMachineFunction - Reduce two-address instructions to two operands.
///
bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
- DEBUG(dbgs() << "Machine Function\n");
const TargetMachine &TM = MF.getTarget();
MRI = &MF.getRegInfo();
TII = TM.getInstrInfo();
InstrItins = TM.getInstrItineraryData();
LV = getAnalysisIfAvailable<LiveVariables>();
AA = &getAnalysis<AliasAnalysis>();
+ OptLevel = TM.getOptLevel();
bool MadeChange = false;
DEBUG(dbgs() << "********** REWRITING TWO-ADDR INSTRS **********\n");
- DEBUG(dbgs() << "********** Function: "
+ DEBUG(dbgs() << "********** Function: "
<< MF.getFunction()->getName() << '\n');
// This pass takes the function out of SSA form.
// If it's safe and profitable, remat the definition instead of
// copying it.
if (DefMI &&
- DefMI->getDesc().isAsCheapAsAMove() &&
+ DefMI->isAsCheapAsAMove() &&
DefMI->isSafeToReMat(TII, AA, regB) &&
isProfitableToReMat(regB, rc, mi, DefMI, mbbi, Dist)){
DEBUG(dbgs() << "2addr: REMATTING : " << *DefMI << "\n");
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);
+ // 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
}
}
+// 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;
+}
+
/// 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
CanCoalesce = false;
break;
}
- // Keep track of one of the uses.
- SomeMI = UseMI;
+ // Keep track of one of the uses. Preferably the first one which has a
+ // <def,undef> flag.
+ if (!SomeMI || UseMI->getOperand(0).isUndef())
+ SomeMI = UseMI;
}
if (!CanCoalesce)
continue;
MachineInstr *CopyMI = BuildMI(*SomeMI->getParent(), SomeMI,
SomeMI->getDebugLoc(),
TII->get(TargetOpcode::COPY))
- .addReg(DstReg, RegState::Define, NewDstSubIdx)
+ .addReg(DstReg, RegState::Define |
+ getUndefRegState(SomeMI->getOperand(0).isUndef()),
+ NewDstSubIdx)
.addReg(SrcReg, 0, NewSrcSubIdx);
// Remove all the old extract instructions.
SmallSet<unsigned, 4> Seen;
for (unsigned i = 1, e = MI->getNumOperands(); i < e; i += 2) {
unsigned SrcReg = MI->getOperand(i).getReg();
+ unsigned SrcSubIdx = MI->getOperand(i).getSubReg();
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);
+ // 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->getVRegDef(SrcReg);
}
- MachineInstr *DefMI = MRI->getVRegDef(SrcReg);
- if (DefMI->isImplicitDef()) {
+ if (DefMI && DefMI->isImplicitDef()) {
DefMI->eraseFromParent();
continue;
}
IsImpDef = false;
// Remember COPY sources. These might be candidate for coalescing.
- if (DefMI->isCopy() && DefMI->getOperand(1).getSubReg())
+ if (DefMI && 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() ||
+ if (!DefMI || !Seen.insert(SrcReg) ||
+ MI->getParent() != DefMI->getParent() ||
!isKill || HasOtherRegSequenceUses(SrcReg, MI, MRI) ||
!TRI->getMatchingSuperRegClass(MRI->getRegClass(DstReg),
MRI->getRegClass(SrcReg), SubIdx)) {
MachineInstr *CopyMI = BuildMI(*MI->getParent(), InsertLoc,
MI->getDebugLoc(), TII->get(TargetOpcode::COPY))
.addReg(DstReg, RegState::Define, SubIdx)
- .addReg(SrcReg, getKillRegState(isKill));
+ .addReg(SrcReg, getKillRegState(isKill), SrcSubIdx);
MI->getOperand(i).setReg(0);
- if (LV && isKill)
+ if (LV && isKill && !TargetRegisterInfo::isPhysicalRegister(SrcReg))
LV->replaceKillInstruction(SrcReg, MI, CopyMI);
DEBUG(dbgs() << "Inserted: " << *CopyMI);
}
UpdateRegSequenceSrcs(SrcReg, DstReg, SubIdx, MRI, *TRI);
}
+ // 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();
+ }
+ // Make sure there is a full non-subreg imp-def operand on the
+ // instruction. This shouldn't be necessary, but it seems that at least
+ // RAFast requires it.
+ Def->addRegisterDefined(DstReg, TRI);
+ DEBUG(dbgs() << "First def: " << *Def);
+ }
+
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);
+ MI->RemoveOperand(j);
} else {
DEBUG(dbgs() << "Eliminated: " << *MI);
MI->eraseFromParent();