#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
STATISTIC(Num3AddrSunk, "Number of 3-address instructions sunk");
STATISTIC(NumReMats, "Number of instructions re-materialized");
STATISTIC(NumDeletes, "Number of dead instructions deleted");
+STATISTIC(NumReSchedUps, "Number of instructions re-scheduled up");
+STATISTIC(NumReSchedDowns, "Number of instructions re-scheduled down");
namespace {
class TwoAddressInstructionPass : public MachineFunctionPass {
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
+ const InstrItineraryData *InstrItins;
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.
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi, unsigned Dist);
+ bool isDefTooClose(unsigned Reg, unsigned Dist,
+ MachineInstr *MI, MachineBasicBlock *MBB);
+
+ bool RescheduleMIBelowKill(MachineBasicBlock *MBB,
+ MachineBasicBlock::iterator &mi,
+ MachineBasicBlock::iterator &nmi,
+ unsigned Reg);
+ bool RescheduleKillAboveMI(MachineBasicBlock *MBB,
+ MachineBasicBlock::iterator &mi,
+ MachineBasicBlock::iterator &nmi,
+ unsigned Reg);
+
bool TryInstructionTransform(MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
MachineFunction::iterator &mbbi,
AU.addPreserved<LiveVariables>();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
- AU.addPreservedID(PHIEliminationID);
MachineFunctionPass::getAnalysisUsage(AU);
}
bool TwoAddressInstructionPass::Sink3AddrInstruction(MachineBasicBlock *MBB,
MachineInstr *MI, unsigned SavedReg,
MachineBasicBlock::iterator OldPos) {
+ // FIXME: Shouldn't we be trying to do this before we three-addressify the
+ // instruction? After this transformation is done, we no longer need
+ // the instruction to be in three-address form.
+
// Check if it's safe to move this instruction.
bool SeenStore = true; // Be conservative.
if (!MI->isSafeToMove(TII, AA, SeenStore))
break;
}
- if (!KillMI || KillMI->getParent() != MBB || KillMI == MI)
+ // If we find the instruction that kills SavedReg, and it is in an
+ // appropriate location, we can try to sink the current instruction
+ // past it.
+ if (!KillMI || KillMI->getParent() != MBB || KillMI == MI ||
+ 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;
}
return false;
}
+/// findLocalKill - Look for an instruction below MI in the MBB that kills the
+/// specified register. Returns null if there are any other Reg use between the
+/// instructions.
+static
+MachineInstr *findLocalKill(unsigned Reg, MachineBasicBlock *MBB,
+ MachineInstr *MI, MachineRegisterInfo *MRI,
+ DenseMap<MachineInstr*, unsigned> &DistanceMap) {
+ MachineInstr *KillMI = 0;
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI->use_nodbg_begin(Reg),
+ UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
+ MachineInstr *UseMI = &*UI;
+ if (UseMI == MI || UseMI->getParent() != MBB)
+ continue;
+ if (DistanceMap.count(UseMI))
+ continue;
+ if (!UI.getOperand().isKill())
+ return 0;
+ if (KillMI)
+ return 0; // -O0 kill markers cannot be trusted?
+ KillMI = UseMI;
+ }
+
+ return KillMI;
+}
+
/// findOnlyInterestingUse - Given a register, if has a single in-basic block
/// use, return the use instruction if it's a copy or a two-address use.
static
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) {
return true;
}
+/// RescheduleMIBelowKill - If there is one more local instruction that reads
+/// 'Reg' and it kills 'Reg, consider moving the instruction below the kill
+/// instruction in order to eliminate the need for the copy.
+bool
+TwoAddressInstructionPass::RescheduleMIBelowKill(MachineBasicBlock *MBB,
+ MachineBasicBlock::iterator &mi,
+ MachineBasicBlock::iterator &nmi,
+ unsigned Reg) {
+ MachineInstr *MI = &*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;
+
+ MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
+ if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
+ // Don't mess with copies, they may be coalesced later.
+ return false;
+
+ if (KillMI->hasUnmodeledSideEffects() || KillMI->isCall() ||
+ KillMI->isBranch() || KillMI->isTerminator())
+ // Don't move pass calls, etc.
+ return false;
+
+ unsigned DstReg;
+ if (isTwoAddrUse(*KillMI, Reg, DstReg))
+ return false;
+
+ bool SeenStore = true;
+ if (!MI->isSafeToMove(TII, AA, SeenStore))
+ return false;
+
+ if (TII->getInstrLatency(InstrItins, MI) > 1)
+ // FIXME: Needs more sophisticated heuristics.
+ 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);
+ if (!MO.isReg())
+ continue;
+ unsigned MOReg = MO.getReg();
+ if (!MOReg)
+ continue;
+ if (MO.isDef())
+ Defs.insert(MOReg);
+ else {
+ Uses.insert(MOReg);
+ if (MO.isKill() && MOReg != Reg)
+ 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;
+ }
+
+ // Check if the reschedule will not break depedencies.
+ unsigned NumVisited = 0;
+ MachineBasicBlock::iterator KillPos = KillMI;
+ ++KillPos;
+ for (MachineBasicBlock::iterator I = To; I != KillPos; ++I) {
+ MachineInstr *OtherMI = I;
+ // DBG_VALUE cannot be counted against the limit.
+ if (OtherMI->isDebugValue())
+ continue;
+ if (NumVisited > 10) // FIXME: Arbitrary limit to reduce compile time cost.
+ return false;
+ ++NumVisited;
+ 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) {
+ const MachineOperand &MO = OtherMI->getOperand(i);
+ if (!MO.isReg())
+ continue;
+ unsigned MOReg = MO.getReg();
+ if (!MOReg)
+ continue;
+ if (MO.isDef()) {
+ if (Uses.count(MOReg))
+ // Physical register use would be clobbered.
+ return false;
+ if (!MO.isDead() && Defs.count(MOReg))
+ // May clobber a physical register def.
+ // FIXME: This may be too conservative. It's ok if the instruction
+ // is sunken completely below the use.
+ return false;
+ } else {
+ if (Defs.count(MOReg))
+ return false;
+ if (MOReg != Reg &&
+ ((MO.isKill() && Uses.count(MOReg)) || Kills.count(MOReg)))
+ // Don't want to extend other live ranges and update kills.
+ return false;
+ }
+ }
+ }
+
+ // Move debug info as well.
+ while (From != MBB->begin() && llvm::prior(From)->isDebugValue())
+ --From;
+
+ // Copies following MI may have been moved as well.
+ nmi = To;
+ MBB->splice(KillPos, MBB, From, To);
+ DistanceMap.erase(DI);
+
+ if (LV) {
+ // Update live variables
+ LV->removeVirtualRegisterKilled(Reg, KillMI);
+ LV->addVirtualRegisterKilled(Reg, MI);
+ } else {
+ for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = KillMI->getOperand(i);
+ if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
+ continue;
+ MO.setIsKill(false);
+ }
+ MI->addRegisterKilled(Reg, 0);
+ }
+
+ return true;
+}
+
+/// isDefTooClose - Return true if the re-scheduling will put the given
+/// instruction too close to the defs of its register dependencies.
+bool TwoAddressInstructionPass::isDefTooClose(unsigned Reg, unsigned Dist,
+ MachineInstr *MI,
+ MachineBasicBlock *MBB) {
+ for (MachineRegisterInfo::def_iterator DI = MRI->def_begin(Reg),
+ DE = MRI->def_end(); DI != DE; ++DI) {
+ MachineInstr *DefMI = &*DI;
+ if (DefMI->getParent() != MBB || DefMI->isCopy() || DefMI->isCopyLike())
+ continue;
+ if (DefMI == MI)
+ return true; // MI is defining something KillMI uses
+ DenseMap<MachineInstr*, unsigned>::iterator DDI = DistanceMap.find(DefMI);
+ if (DDI == DistanceMap.end())
+ return true; // Below MI
+ unsigned DefDist = DDI->second;
+ assert(Dist > DefDist && "Visited def already?");
+ if (TII->getInstrLatency(InstrItins, DefMI) > (int)(Dist - DefDist))
+ return true;
+ }
+ return false;
+}
+
+/// RescheduleKillAboveMI - If there is one more local instruction that reads
+/// 'Reg' and it kills 'Reg, consider moving the kill instruction above the
+/// current two-address instruction in order to eliminate the need for the
+/// copy.
+bool
+TwoAddressInstructionPass::RescheduleKillAboveMI(MachineBasicBlock *MBB,
+ MachineBasicBlock::iterator &mi,
+ MachineBasicBlock::iterator &nmi,
+ unsigned Reg) {
+ MachineInstr *MI = &*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;
+
+ MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
+ if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
+ // Don't mess with copies, they may be coalesced later.
+ return false;
+
+ unsigned DstReg;
+ if (isTwoAddrUse(*KillMI, Reg, DstReg))
+ return false;
+
+ bool SeenStore = true;
+ if (!KillMI->isSafeToMove(TII, AA, SeenStore))
+ return false;
+
+ SmallSet<unsigned, 2> Uses;
+ SmallSet<unsigned, 2> Kills;
+ SmallSet<unsigned, 2> Defs;
+ SmallSet<unsigned, 2> LiveDefs;
+ for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = KillMI->getOperand(i);
+ if (!MO.isReg())
+ continue;
+ unsigned MOReg = MO.getReg();
+ if (MO.isUse()) {
+ if (!MOReg)
+ continue;
+ if (isDefTooClose(MOReg, DI->second, MI, MBB))
+ return false;
+ Uses.insert(MOReg);
+ if (MO.isKill() && MOReg != Reg)
+ Kills.insert(MOReg);
+ } else if (TargetRegisterInfo::isPhysicalRegister(MOReg)) {
+ Defs.insert(MOReg);
+ if (!MO.isDead())
+ LiveDefs.insert(MOReg);
+ }
+ }
+
+ // Check if the reschedule will not break depedencies.
+ unsigned NumVisited = 0;
+ MachineBasicBlock::iterator KillPos = KillMI;
+ for (MachineBasicBlock::iterator I = mi; I != KillPos; ++I) {
+ MachineInstr *OtherMI = I;
+ // DBG_VALUE cannot be counted against the limit.
+ if (OtherMI->isDebugValue())
+ continue;
+ if (NumVisited > 10) // FIXME: Arbitrary limit to reduce compile time cost.
+ return false;
+ ++NumVisited;
+ 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())
+ continue;
+ unsigned MOReg = MO.getReg();
+ if (!MOReg)
+ continue;
+ if (MO.isUse()) {
+ if (Defs.count(MOReg))
+ // Moving KillMI can clobber the physical register if the def has
+ // not been seen.
+ return false;
+ if (Kills.count(MOReg))
+ // Don't want to extend other live ranges and update kills.
+ return false;
+ } else {
+ 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.
+ MachineBasicBlock::iterator InsertPos = mi;
+ while (InsertPos != MBB->begin() && llvm::prior(InsertPos)->isDebugValue())
+ --InsertPos;
+ MachineBasicBlock::iterator From = KillMI;
+ MachineBasicBlock::iterator To = llvm::next(From);
+ while (llvm::prior(From)->isDebugValue())
+ --From;
+ MBB->splice(InsertPos, MBB, From, To);
+
+ nmi = llvm::prior(InsertPos); // Backtrack so we process the moved instr.
+ DistanceMap.erase(DI);
+
+ if (LV) {
+ // Update live variables
+ LV->removeVirtualRegisterKilled(Reg, KillMI);
+ LV->addVirtualRegisterKilled(Reg, MI);
+ } else {
+ for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = KillMI->getOperand(i);
+ if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
+ continue;
+ MO.setIsKill(false);
+ }
+ MI->addRegisterKilled(Reg, 0);
+ }
+ return true;
+}
+
/// 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
MachineFunction::iterator &mbbi,
unsigned SrcIdx, unsigned DstIdx, unsigned Dist,
SmallPtrSet<MachineInstr*, 8> &Processed) {
- const MCInstrDesc &MCID = mi->getDesc();
- unsigned regA = mi->getOperand(DstIdx).getReg();
- unsigned regB = mi->getOperand(SrcIdx).getReg();
+ if (OptLevel == CodeGenOpt::None)
+ return false;
+
+ MachineInstr &MI = *mi;
+ unsigned regA = MI.getOperand(DstIdx).getReg();
+ unsigned regB = MI.getOperand(SrcIdx).getReg();
assert(TargetRegisterInfo::isVirtualRegister(regB) &&
"cannot make instruction into two-address form");
// If regA is dead and the instruction can be deleted, just delete
// it so it doesn't clobber regB.
- bool regBKilled = isKilled(*mi, regB, MRI, TII);
- if (!regBKilled && mi->getOperand(DstIdx).isDead() &&
+ bool regBKilled = isKilled(MI, regB, MRI, TII);
+ if (!regBKilled && MI.getOperand(DstIdx).isDead() &&
DeleteUnusedInstr(mi, nmi, mbbi, Dist)) {
++NumDeletes;
return true; // Done with this instruction.
unsigned regCIdx = ~0U;
bool TryCommute = false;
bool AggressiveCommute = false;
- if (MCID.isCommutable() && mi->getNumOperands() >= 3 &&
- TII->findCommutedOpIndices(mi, SrcOp1, SrcOp2)) {
+ if (MI.isCommutable() && MI.getNumOperands() >= 3 &&
+ TII->findCommutedOpIndices(&MI, SrcOp1, SrcOp2)) {
if (SrcIdx == SrcOp1)
regCIdx = SrcOp2;
else if (SrcIdx == SrcOp2)
regCIdx = SrcOp1;
if (regCIdx != ~0U) {
- regC = mi->getOperand(regCIdx).getReg();
- if (!regBKilled && isKilled(*mi, regC, MRI, TII))
+ regC = MI.getOperand(regCIdx).getReg();
+ if (!regBKilled && isKilled(MI, regC, MRI, TII))
// 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;
- else if (isProfitableToCommute(regB, regC, mi, mbbi, Dist)) {
+ else if (isProfitableToCommute(regB, regC, &MI, mbbi, Dist)) {
TryCommute = true;
AggressiveCommute = true;
}
return false;
}
+ // If there is one more use of regB later in the same MBB, consider
+ // re-schedule this MI below it.
+ if (RescheduleMIBelowKill(mbbi, mi, nmi, regB)) {
+ ++NumReSchedDowns;
+ return false;
+ }
+
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)) {
}
}
+ // If there is one more use of regB later in the same MBB, consider
+ // re-schedule it before this MI if it's legal.
+ if (RescheduleKillAboveMI(mbbi, mi, nmi, regB)) {
+ ++NumReSchedUps;
+ return false;
+ }
+
// If this is an instruction with a load folded into it, try unfolding
// the load, e.g. avoid this:
// movq %rdx, %rcx
// 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 =
- TII->getOpcodeAfterMemoryUnfold(mi->getOpcode(),
+ TII->getOpcodeAfterMemoryUnfold(MI.getOpcode(),
/*UnfoldLoad=*/true,
/*UnfoldStore=*/false,
&LoadRegIndex);
MachineFunction &MF = *mbbi->getParent();
// Unfold the load.
- DEBUG(dbgs() << "2addr: UNFOLDING: " << *mi);
+ DEBUG(dbgs() << "2addr: UNFOLDING: " << MI);
const TargetRegisterClass *RC =
TII->getRegClass(UnfoldMCID, LoadRegIndex, TRI);
unsigned Reg = MRI->createVirtualRegister(RC);
SmallVector<MachineInstr *, 2> NewMIs;
- if (!TII->unfoldMemoryOperand(MF, mi, Reg,
+ if (!TII->unfoldMemoryOperand(MF, &MI, Reg,
/*UnfoldLoad=*/true,/*UnfoldStore=*/false,
NewMIs)) {
DEBUG(dbgs() << "2addr: ABANDONING UNFOLD\n");
// 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() &&
+ 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]);
+ 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]);
+ LV->replaceKillInstruction(MO.getReg(), &MI, NewMIs[1]);
}
}
- } else if (LV->removeVirtualRegisterDead(MO.getReg(), mi)) {
+ } else if (LV->removeVirtualRegisterDead(MO.getReg(), &MI)) {
if (NewMIs[1]->registerDefIsDead(MO.getReg()))
LV->addVirtualRegisterDead(MO.getReg(), NewMIs[1]);
else {
}
LV->addVirtualRegisterKilled(Reg, NewMIs[1]);
}
- mi->eraseFromParent();
+ MI.eraseFromParent();
mi = NewMIs[1];
if (TransformSuccess)
return true;
/// 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();
TRI = TM.getRegisterInfo();
+ 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.
+ MRI->leaveSSA();
+
// ReMatRegs - Keep track of the registers whose def's are remat'ed.
BitVector ReMatRegs(MRI->getNumVirtRegs());
// 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");
}
}
+// 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();
projects / oota-llvm.git / blobdiff