#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
cl::desc("Avoid coalescing cross register class copies"),
cl::init(false), cl::Hidden);
-static cl::opt<bool>
-PhysJoinTweak("tweak-phys-join-heuristics",
- cl::desc("Tweak heuristics for joining phys reg with vr"),
- cl::init(false), cl::Hidden);
-
static RegisterPass<SimpleRegisterCoalescing>
X("simple-register-coalescing", "Simple Register Coalescing");
for (const unsigned* SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR)
if (li_->hasInterval(*SR) && IntA.overlaps(li_->getInterval(*SR))) {
DEBUG({
- dbgs() << "Interfere with sub-register ";
+ dbgs() << "\t\tInterfere with sub-register ";
li_->getInterval(*SR).print(dbgs(), tri_);
});
return false;
}
DEBUG({
- dbgs() << "\nExtending: ";
+ dbgs() << "Extending: ";
IntB.print(dbgs(), tri_);
});
// If the copy instruction was killing the destination register before the
// merge, find the last use and trim the live range. That will also add the
// isKill marker.
- if (CopyMI->killsRegister(IntA.reg))
+ if (ALR->valno->isKill(CopyIdx))
TrimLiveIntervalToLastUse(CopyUseIdx, CopyMI->getParent(), IntA, ALR);
++numExtends;
for (; BI != IntB.ranges.end() && AI->end >= BI->start; ++BI) {
if (BI->valno == BValNo)
continue;
+ // When BValNo is null, we're looking for a dummy clobber-value for a subreg.
+ if (!BValNo && !BI->valno->isDefAccurate() && !BI->valno->getCopy())
+ continue;
if (BI->start <= AI->start && BI->end > AI->start)
return true;
if (BI->start > AI->start && BI->start < AI->end)
if (HasOtherReachingDefs(IntA, IntB, AValNo, BValNo))
return false;
+ bool BHasSubRegs = false;
+ if (TargetRegisterInfo::isPhysicalRegister(IntB.reg))
+ BHasSubRegs = *tri_->getSubRegisters(IntB.reg);
+
+ // Abort if the subregisters of IntB.reg have values that are not simply the
+ // clobbers from the superreg.
+ if (BHasSubRegs)
+ for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR)
+ if (HasOtherReachingDefs(IntA, li_->getInterval(*SR), AValNo, 0))
+ return false;
+
// If some of the uses of IntA.reg is already coalesced away, return false.
// It's not possible to determine whether it's safe to perform the coalescing.
for (MachineRegisterInfo::use_nodbg_iterator UI =
BExtend[ALR->end] = BLR->end;
// Update uses of IntA of the specific Val# with IntB.
- bool BHasSubRegs = false;
- if (TargetRegisterInfo::isPhysicalRegister(IntB.reg))
- BHasSubRegs = *tri_->getSubRegisters(IntB.reg);
for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
UE = mri_->use_end(); UI != UE;) {
MachineOperand &UseMO = UI.getOperand();
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
continue;
- if (DstReg == IntB.reg) {
+ if (DstReg == IntB.reg && DstSubIdx == 0) {
// This copy will become a noop. If it's defining a new val#,
// remove that val# as well. However this live range is being
// extended to the end of the existing live range defined by the copy.
// We need to insert a new liverange: [ALR.start, LastUse). It may be we can
// simply extend BLR if CopyMI doesn't end the range.
DEBUG({
- dbgs() << "\nExtending: ";
+ dbgs() << "Extending: ";
IntB.print(dbgs(), tri_);
});
DEBUG({
dbgs() << " result = ";
IntB.print(dbgs(), tri_);
- dbgs() << '\n';
dbgs() << "\nShortening: ";
IntA.print(dbgs(), tri_);
});
LR->valno->addKill(LastUseIdx.getDefIndex());
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
- DstReg == li.reg) {
+ DstReg == li.reg && DstSubIdx == 0) {
// Last use is itself an identity code.
- int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
+ int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg,
+ false, false, tri_);
LastUseMI->getOperand(DeadIdx).setIsDead();
}
return true;
if (!tii_->isTriviallyReMaterializable(DefMI, AA))
return false;
bool SawStore = false;
- if (!DefMI->isSafeToMove(tii_, SawStore, AA))
+ if (!DefMI->isSafeToMove(tii_, AA, SawStore))
return false;
if (TID.getNumDefs() != 1)
return false;
for (const unsigned* SR = tri_->getSubRegisters(DstReg); *SR; ++SR) {
if (!li_->hasInterval(*SR))
continue;
- DLR = li_->getInterval(*SR).getLiveRangeContaining(DefIdx);
+ const LiveRange *DLR =
+ li_->getInterval(*SR).getLiveRangeContaining(DefIdx);
if (DLR && DLR->valno->getCopy() == CopyMI)
DLR->valno->setCopy(0);
}
// kill.
bool checkForDeadDef = false;
MachineBasicBlock *MBB = CopyMI->getParent();
- if (CopyMI->killsRegister(SrcInt.reg))
+ if (SrcLR->valno->isKill(DefIdx))
if (!TrimLiveIntervalToLastUse(CopyIdx, MBB, SrcInt, SrcLR)) {
checkForDeadDef = true;
}
NewMI->addOperand(MO);
if (MO.isDef() && li_->hasInterval(MO.getReg())) {
unsigned Reg = MO.getReg();
- DLR = li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
+ const LiveRange *DLR =
+ li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
if (DLR && DLR->valno->getCopy() == CopyMI)
DLR->valno->setCopy(0);
+ // Handle subregs as well
+ if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+ for (const unsigned* SR = tri_->getSubRegisters(Reg); *SR; ++SR) {
+ if (!li_->hasInterval(*SR))
+ continue;
+ const LiveRange *DLR =
+ li_->getInterval(*SR).getLiveRangeContaining(DefIdx);
+ if (DLR && DLR->valno->getCopy() == CopyMI)
+ DLR->valno->setCopy(0);
+ }
+ }
}
}
CopyMI->eraseFromParent();
ReMatCopies.insert(CopyMI);
ReMatDefs.insert(DefMI);
+ DEBUG(dbgs() << "Remat: " << *NewMI);
++NumReMats;
return true;
}
unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
CopySrcSubIdx, CopyDstSubIdx) &&
+ CopySrcSubIdx == 0 &&
+ CopyDstSubIdx == 0 &&
CopySrcReg != CopyDstReg &&
CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
// If the use is a copy and it won't be coalesced away, and its source
// is defined by a trivial computation, try to rematerialize it instead.
- if (ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,
+ if (!JoinedCopies.count(UseMI) &&
+ ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,
CopyDstSubIdx, UseMI))
continue;
}
UseMI->isRegTiedToDefOperand(&O-&UseMI->getOperand(0))))
UseMI->addRegisterKilled(DstReg, tri_, true);
}
+
+ DEBUG({
+ dbgs() << "\t\tupdated: ";
+ if (!UseMI->isDebugValue())
+ dbgs() << li_->getInstructionIndex(UseMI) << "\t";
+ dbgs() << *UseMI;
+ });
continue;
}
// EAX: 1 -> AL, 2 -> AX
// So RAX's sub-register 2 is AX, RAX's sub-regsiter 3 is EAX, whose
// sub-register 2 is also AX.
+ //
+ // FIXME: Properly compose subreg indices for all targets.
+ //
if (SubIdx && OldSubIdx && SubIdx != OldSubIdx)
- assert(OldSubIdx < SubIdx && "Conflicting sub-register index!");
+ ;
else if (SubIdx)
O.setSubReg(SubIdx);
- // Remove would-be duplicated kill marker.
- if (O.isKill() && UseMI->killsRegister(DstReg))
- O.setIsKill(false);
O.setReg(DstReg);
+ DEBUG({
+ dbgs() << "\t\tupdated: ";
+ if (!UseMI->isDebugValue())
+ dbgs() << li_->getInstructionIndex(UseMI) << "\t";
+ dbgs() << *UseMI;
+ });
+
// After updating the operand, check if the machine instruction has
// become a copy. If so, update its val# information.
if (JoinedCopies.count(UseMI))
}
}
-/// RemoveUnnecessaryKills - Remove kill markers that are no longer accurate
-/// due to live range lengthening as the result of coalescing.
-void SimpleRegisterCoalescing::RemoveUnnecessaryKills(unsigned Reg,
- LiveInterval &LI) {
- for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
- UE = mri_->use_end(); UI != UE; ++UI) {
- MachineOperand &UseMO = UI.getOperand();
- if (!UseMO.isKill())
- continue;
- MachineInstr *UseMI = UseMO.getParent();
- SlotIndex UseIdx =
- li_->getInstructionIndex(UseMI).getUseIndex();
- const LiveRange *LR = LI.getLiveRangeContaining(UseIdx);
- if (!LR ||
- (!LR->valno->isKill(UseIdx.getDefIndex()) &&
- LR->valno->def != UseIdx.getDefIndex())) {
- // Interesting problem. After coalescing reg1027's def and kill are both
- // at the same point: %reg1027,0.000000e+00 = [56,814:0) 0@70-(814)
- //
- // bb5:
- // 60 %reg1027<def> = t2MOVr %reg1027, 14, %reg0, %reg0
- // 68 %reg1027<def> = t2LDRi12 %reg1027<kill>, 8, 14, %reg0
- // 76 t2CMPzri %reg1038<kill,undef>, 0, 14, %reg0, %CPSR<imp-def>
- // 84 %reg1027<def> = t2MOVr %reg1027, 14, %reg0, %reg0
- // 96 t2Bcc mbb<bb5,0x2030910>, 1, %CPSR<kill>
- //
- // Do not remove the kill marker on t2LDRi12.
- UseMO.setIsKill(false);
- }
- }
-}
-
/// removeIntervalIfEmpty - Check if the live interval of a physical register
/// is empty, if so remove it and also remove the empty intervals of its
/// sub-registers. Return true if live interval is removed.
MachineInstr *DefMI =
li_->getInstructionFromIndex(LRStart.getDefIndex());
if (DefMI && DefMI != CopyMI) {
- int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg, false);
+ int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg);
if (DeadIdx != -1)
DefMI->getOperand(DeadIdx).setIsDead();
else
unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
unsigned Length = li_->getApproximateInstructionCount(DstInt);
if (Length > Threshold &&
- (((float)std::distance(mri_->use_nodbg_begin(DstInt.reg),
- mri_->use_nodbg_end()) / Length) <
- (1.0 / Threshold)))
+ std::distance(mri_->use_nodbg_begin(DstInt.reg),
+ mri_->use_nodbg_end()) * Threshold < Length)
return false;
// If the virtual register live interval extends into a loop, turn down
unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
unsigned Length = li_->getApproximateInstructionCount(SrcInt);
if (Length > Threshold &&
- (((float)std::distance(mri_->use_nodbg_begin(SrcInt.reg),
- mri_->use_nodbg_end()) / Length) <
- (1.0 / Threshold)))
+ std::distance(mri_->use_nodbg_begin(SrcInt.reg),
+ mri_->use_nodbg_end()) * Threshold < Length)
return false;
if (SrcInt.empty())
/// isWinToJoinCrossClass - Return true if it's profitable to coalesce
/// two virtual registers from different register classes.
bool
-SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned LargeReg,
- unsigned SmallReg,
- unsigned Threshold) {
- // Then make sure the intervals are *short*.
- LiveInterval &LargeInt = li_->getInterval(LargeReg);
- LiveInterval &SmallInt = li_->getInterval(SmallReg);
- unsigned LargeSize = li_->getApproximateInstructionCount(LargeInt);
- unsigned SmallSize = li_->getApproximateInstructionCount(SmallInt);
- if (LargeSize > Threshold) {
- unsigned SmallUses = std::distance(mri_->use_nodbg_begin(SmallReg),
- mri_->use_nodbg_end());
- unsigned LargeUses = std::distance(mri_->use_nodbg_begin(LargeReg),
- mri_->use_nodbg_end());
- if (SmallUses*LargeSize < LargeUses*SmallSize)
+SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned SrcReg,
+ unsigned DstReg,
+ const TargetRegisterClass *SrcRC,
+ const TargetRegisterClass *DstRC,
+ const TargetRegisterClass *NewRC) {
+ unsigned NewRCCount = allocatableRCRegs_[NewRC].count();
+ // This heuristics is good enough in practice, but it's obviously not *right*.
+ // 4 is a magic number that works well enough for x86, ARM, etc. It filter
+ // out all but the most restrictive register classes.
+ if (NewRCCount > 4 ||
+ // Early exit if the function is fairly small, coalesce aggressively if
+ // that's the case. For really special register classes with 3 or
+ // fewer registers, be a bit more careful.
+ (li_->getFuncInstructionCount() / NewRCCount) < 8)
+ return true;
+ LiveInterval &SrcInt = li_->getInterval(SrcReg);
+ LiveInterval &DstInt = li_->getInterval(DstReg);
+ unsigned SrcSize = li_->getApproximateInstructionCount(SrcInt);
+ unsigned DstSize = li_->getApproximateInstructionCount(DstInt);
+ if (SrcSize <= NewRCCount && DstSize <= NewRCCount)
+ return true;
+ // Estimate *register use density*. If it doubles or more, abort.
+ unsigned SrcUses = std::distance(mri_->use_nodbg_begin(SrcReg),
+ mri_->use_nodbg_end());
+ unsigned DstUses = std::distance(mri_->use_nodbg_begin(DstReg),
+ mri_->use_nodbg_end());
+ unsigned NewUses = SrcUses + DstUses;
+ unsigned NewSize = SrcSize + DstSize;
+ if (SrcRC != NewRC && SrcSize > NewRCCount) {
+ unsigned SrcRCCount = allocatableRCRegs_[SrcRC].count();
+ if (NewUses*SrcSize*SrcRCCount > 2*SrcUses*NewSize*NewRCCount)
+ return false;
+ }
+ if (DstRC != NewRC && DstSize > NewRCCount) {
+ unsigned DstRCCount = allocatableRCRegs_[DstRC].count();
+ if (NewUses*DstSize*DstRCCount > 2*DstUses*NewSize*NewRCCount)
return false;
}
return true;
unsigned &RealDstReg) {
const TargetRegisterClass *RC = mri_->getRegClass(SrcReg);
RealDstReg = tri_->getMatchingSuperReg(DstReg, SubIdx, RC);
- assert(RealDstReg && "Invalid extract_subreg instruction!");
+ if (!RealDstReg) {
+ DEBUG(dbgs() << "\tIncompatible source regclass: "
+ << "none of the super-registers of " << tri_->getName(DstReg)
+ << " are in " << RC->getName() << ".\n");
+ return false;
+ }
+ LiveInterval &RHS = li_->getInterval(SrcReg);
// For this type of EXTRACT_SUBREG, conservatively
// check if the live interval of the source register interfere with the
// actual super physical register we are trying to coalesce with.
- LiveInterval &RHS = li_->getInterval(SrcReg);
if (li_->hasInterval(RealDstReg) &&
RHS.overlaps(li_->getInterval(RealDstReg))) {
DEBUG({
- dbgs() << "Interfere with register ";
+ dbgs() << "\t\tInterfere with register ";
li_->getInterval(RealDstReg).print(dbgs(), tri_);
});
return false; // Not coalescable
}
for (const unsigned* SR = tri_->getSubRegisters(RealDstReg); *SR; ++SR)
- if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
+ // Do not check DstReg or its sub-register. JoinIntervals() will take care
+ // of that.
+ if (*SR != DstReg &&
+ !tri_->isSubRegister(DstReg, *SR) &&
+ li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
DEBUG({
- dbgs() << "Interfere with sub-register ";
+ dbgs() << "\t\tInterfere with sub-register ";
li_->getInterval(*SR).print(dbgs(), tri_);
});
return false; // Not coalescable
unsigned &RealSrcReg) {
const TargetRegisterClass *RC = mri_->getRegClass(DstReg);
RealSrcReg = tri_->getMatchingSuperReg(SrcReg, SubIdx, RC);
- assert(RealSrcReg && "Invalid extract_subreg instruction!");
+ if (!RealSrcReg) {
+ DEBUG(dbgs() << "\tIncompatible destination regclass: "
+ << "none of the super-registers of " << tri_->getName(SrcReg)
+ << " are in " << RC->getName() << ".\n");
+ return false;
+ }
- LiveInterval &RHS = li_->getInterval(DstReg);
+ LiveInterval &LHS = li_->getInterval(DstReg);
if (li_->hasInterval(RealSrcReg) &&
- RHS.overlaps(li_->getInterval(RealSrcReg))) {
+ LHS.overlaps(li_->getInterval(RealSrcReg))) {
DEBUG({
- dbgs() << "Interfere with register ";
+ dbgs() << "\t\tInterfere with register ";
li_->getInterval(RealSrcReg).print(dbgs(), tri_);
});
return false; // Not coalescable
}
for (const unsigned* SR = tri_->getSubRegisters(RealSrcReg); *SR; ++SR)
- if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
+ // Do not check SrcReg or its sub-register. JoinIntervals() will take care
+ // of that.
+ if (*SR != SrcReg &&
+ !tri_->isSubRegister(SrcReg, *SR) &&
+ li_->hasInterval(*SR) && LHS.overlaps(li_->getInterval(*SR))) {
DEBUG({
- dbgs() << "Interfere with sub-register ";
+ dbgs() << "\t\tInterfere with sub-register ";
li_->getInterval(*SR).print(dbgs(), tri_);
});
return false; // Not coalescable
return false; // Not coalescable.
}
+ // We cannot handle dual subreg indices and mismatched classes at the same
+ // time.
+ if (SrcSubIdx && DstSubIdx && differingRegisterClasses(SrcReg, DstReg)) {
+ DEBUG(dbgs() << "\tCannot handle subreg indices and mismatched classes.\n");
+ return false;
+ }
+
// Check that a physical source register is compatible with dst regclass
if (SrcIsPhys) {
unsigned SrcSubReg = SrcSubIdx ?
assert(DstSubRC && "Illegal subregister index");
if (!DstSubRC->contains(SrcSubReg)) {
DEBUG(dbgs() << "\tIncompatible destination regclass: "
- << tri_->getName(SrcSubReg) << " not in "
+ << "none of the super-registers of "
+ << tri_->getName(SrcSubReg) << " are in "
<< DstSubRC->getName() << ".\n");
return false; // Not coalescable.
}
assert(SrcSubRC && "Illegal subregister index");
if (!SrcSubRC->contains(DstSubReg)) {
DEBUG(dbgs() << "\tIncompatible source regclass: "
- << tri_->getName(DstSubReg) << " not in "
+ << "none of the super-registers of "
+ << tri_->getName(DstSubReg) << " are in "
<< SrcSubRC->getName() << ".\n");
(void)DstSubReg;
return false; // Not coalescable.
const TargetRegisterClass *SrcRC= SrcIsPhys ? 0 : mri_->getRegClass(SrcReg);
const TargetRegisterClass *DstRC= DstIsPhys ? 0 : mri_->getRegClass(DstReg);
const TargetRegisterClass *NewRC = NULL;
- MachineBasicBlock *CopyMBB = CopyMI->getParent();
unsigned RealDstReg = 0;
unsigned RealSrcReg = 0;
if (isExtSubReg || isInsSubReg || isSubRegToReg) {
return false; // Not coalescable.
}
+ // FIXME: The following checks are somewhat conservative. Perhaps a better
+ // way to implement this is to treat this as coalescing a vr with the
+ // super physical register.
if (isExtSubReg) {
if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealDstReg))
return false; // Not coalescable
return false; // Not coalescable
}
- unsigned LargeReg = isExtSubReg ? SrcReg : DstReg;
- unsigned SmallReg = isExtSubReg ? DstReg : SrcReg;
- unsigned Limit= allocatableRCRegs_[mri_->getRegClass(SmallReg)].count();
- if (!isWinToJoinCrossClass(LargeReg, SmallReg, Limit)) {
+ if (!isWinToJoinCrossClass(SrcReg, DstReg, SrcRC, DstRC, NewRC)) {
+ DEBUG(dbgs() << "\tAvoid coalescing to constrained register class: "
+ << SrcRC->getName() << "/"
+ << DstRC->getName() << " -> "
+ << NewRC->getName() << ".\n");
Again = true; // May be possible to coalesce later.
return false;
}
}
}
- unsigned LargeReg = SrcReg;
- unsigned SmallReg = DstReg;
-
// Now determine the register class of the joined register.
- if (isExtSubReg) {
- if (SubIdx && DstRC && DstRC->isASubClass()) {
- // This is a move to a sub-register class. However, the source is a
- // sub-register of a larger register class. We don't know what should
- // the register class be. FIXME.
- Again = true;
- return false;
+ if (!SrcIsPhys && !DstIsPhys) {
+ if (isExtSubReg) {
+ NewRC =
+ SubIdx ? tri_->getMatchingSuperRegClass(SrcRC, DstRC, SubIdx) : SrcRC;
+ } else if (isInsSubReg) {
+ NewRC =
+ SubIdx ? tri_->getMatchingSuperRegClass(DstRC, SrcRC, SubIdx) : DstRC;
+ } else {
+ NewRC = getCommonSubClass(SrcRC, DstRC);
}
- if (!DstIsPhys && !SrcIsPhys)
- NewRC = SrcRC;
- } else if (!SrcIsPhys && !DstIsPhys) {
- NewRC = getCommonSubClass(SrcRC, DstRC);
+
if (!NewRC) {
DEBUG(dbgs() << "\tDisjoint regclasses: "
<< SrcRC->getName() << ", "
<< DstRC->getName() << ".\n");
return false; // Not coalescable.
}
- if (DstRC->getSize() > SrcRC->getSize())
- std::swap(LargeReg, SmallReg);
- }
- // If we are joining two virtual registers and the resulting register
- // class is more restrictive (fewer register, smaller size). Check if it's
- // worth doing the merge.
- if (!SrcIsPhys && !DstIsPhys &&
- (isExtSubReg || DstRC->isASubClass()) &&
- !isWinToJoinCrossClass(LargeReg, SmallReg,
- allocatableRCRegs_[NewRC].count())) {
- DEBUG(dbgs() << "\tSrc/Dest are different register classes: "
- << SrcRC->getName() << "/"
- << DstRC->getName() << " -> "
- << NewRC->getName() << ".\n");
- // Allow the coalescer to try again in case either side gets coalesced to
- // a physical register that's compatible with the other side. e.g.
- // r1024 = MOV32to32_ r1025
- // But later r1024 is assigned EAX then r1025 may be coalesced with EAX.
- Again = true; // May be possible to coalesce later.
- return false;
+ // If we are joining two virtual registers and the resulting register
+ // class is more restrictive (fewer register, smaller size). Check if it's
+ // worth doing the merge.
+ if (!isWinToJoinCrossClass(SrcReg, DstReg, SrcRC, DstRC, NewRC)) {
+ DEBUG(dbgs() << "\tAvoid coalescing to constrained register class: "
+ << SrcRC->getName() << "/"
+ << DstRC->getName() << " -> "
+ << NewRC->getName() << ".\n");
+ // Allow the coalescer to try again in case either side gets coalesced to
+ // a physical register that's compatible with the other side. e.g.
+ // r1024 = MOV32to32_ r1025
+ // But later r1024 is assigned EAX then r1025 may be coalesced with EAX.
+ Again = true; // May be possible to coalesce later.
+ return false;
+ }
}
}
"Register mapping is horribly broken!");
DEBUG({
- dbgs() << "\t\tInspecting "; SrcInt.print(dbgs(), tri_);
- dbgs() << " and "; DstInt.print(dbgs(), tri_);
- dbgs() << ": ";
+ dbgs() << "\t\tInspecting ";
+ if (SrcRC) dbgs() << SrcRC->getName() << ": ";
+ SrcInt.print(dbgs(), tri_);
+ dbgs() << "\n\t\t and ";
+ if (DstRC) dbgs() << DstRC->getName() << ": ";
+ DstInt.print(dbgs(), tri_);
+ dbgs() << "\n";
});
// Save a copy of the virtual register live interval. We'll manually
// merge this into the "real" physical register live interval this is
// coalesced with.
- LiveInterval *SavedLI = 0;
+ OwningPtr<LiveInterval> SavedLI;
if (RealDstReg)
- SavedLI = li_->dupInterval(&SrcInt);
+ SavedLI.reset(li_->dupInterval(&SrcInt));
else if (RealSrcReg)
- SavedLI = li_->dupInterval(&DstInt);
+ SavedLI.reset(li_->dupInterval(&DstInt));
- // Check if it is necessary to propagate "isDead" property.
if (!isExtSubReg && !isInsSubReg && !isSubRegToReg) {
+ // Check if it is necessary to propagate "isDead" property.
MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg, false);
bool isDead = mopd->isDead();
// these are not spillable! If the destination interval uses are far away,
// think twice about coalescing them!
if (!isDead && (SrcIsPhys || DstIsPhys)) {
- // If the copy is in a loop, take care not to coalesce aggressively if the
- // src is coming in from outside the loop (or the dst is out of the loop).
- // If it's not in a loop, then determine whether to join them base purely
- // by the length of the interval.
- if (PhysJoinTweak) {
- if (SrcIsPhys) {
- if (!isWinToJoinVRWithSrcPhysReg(CopyMI, CopyMBB, DstInt, SrcInt)) {
- mri_->setRegAllocationHint(DstInt.reg, 0, SrcReg);
- ++numAborts;
- DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
- Again = true; // May be possible to coalesce later.
- return false;
- }
- } else {
- if (!isWinToJoinVRWithDstPhysReg(CopyMI, CopyMBB, DstInt, SrcInt)) {
- mri_->setRegAllocationHint(SrcInt.reg, 0, DstReg);
- ++numAborts;
- DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
- Again = true; // May be possible to coalesce later.
- return false;
- }
- }
- } else {
- // If the virtual register live interval is long but it has low use
- // density, do not join them, instead mark the physical register as its
- // allocation preference.
- LiveInterval &JoinVInt = SrcIsPhys ? DstInt : SrcInt;
- unsigned JoinVReg = SrcIsPhys ? DstReg : SrcReg;
- unsigned JoinPReg = SrcIsPhys ? SrcReg : DstReg;
- const TargetRegisterClass *RC = mri_->getRegClass(JoinVReg);
- unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
- unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
- float Ratio = 1.0 / Threshold;
- if (Length > Threshold &&
- (((float)std::distance(mri_->use_nodbg_begin(JoinVReg),
- mri_->use_nodbg_end()) / Length) < Ratio)) {
- mri_->setRegAllocationHint(JoinVInt.reg, 0, JoinPReg);
- ++numAborts;
- DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
- Again = true; // May be possible to coalesce later.
- return false;
- }
+ // If the virtual register live interval is long but it has low use
+ // density, do not join them, instead mark the physical register as its
+ // allocation preference.
+ LiveInterval &JoinVInt = SrcIsPhys ? DstInt : SrcInt;
+ LiveInterval &JoinPInt = SrcIsPhys ? SrcInt : DstInt;
+ unsigned JoinVReg = SrcIsPhys ? DstReg : SrcReg;
+ unsigned JoinPReg = SrcIsPhys ? SrcReg : DstReg;
+
+ // Don't join with physregs that have a ridiculous number of live
+ // ranges. The data structure performance is really bad when that
+ // happens.
+ if (JoinPInt.ranges.size() > 1000) {
+ mri_->setRegAllocationHint(JoinVInt.reg, 0, JoinPReg);
+ ++numAborts;
+ DEBUG(dbgs()
+ << "\tPhysical register live interval too complicated, abort!\n");
+ return false;
+ }
+
+ const TargetRegisterClass *RC = mri_->getRegClass(JoinVReg);
+ unsigned Threshold = allocatableRCRegs_[RC].count() * 2;
+ unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
+ if (Length > Threshold &&
+ std::distance(mri_->use_nodbg_begin(JoinVReg),
+ mri_->use_nodbg_end()) * Threshold < Length) {
+ // Before giving up coalescing, if definition of source is defined by
+ // trivial computation, try rematerializing it.
+ if (ReMaterializeTrivialDef(SrcInt, DstReg, DstSubIdx, CopyMI))
+ return true;
+
+ mri_->setRegAllocationHint(JoinVInt.reg, 0, JoinPReg);
+ ++numAborts;
+ DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
+ Again = true; // May be possible to coalesce later.
+ return false;
}
}
}
// been modified, so we can use this information below to update aliases.
bool Swapped = false;
// If SrcInt is implicitly defined, it's safe to coalesce.
- bool isEmpty = SrcInt.empty();
- if (isEmpty && !CanCoalesceWithImpDef(CopyMI, DstInt, SrcInt)) {
- // Only coalesce an empty interval (defined by implicit_def) with
- // another interval which has a valno defined by the CopyMI and the CopyMI
- // is a kill of the implicit def.
- DEBUG(dbgs() << "Not profitable!\n");
- return false;
- }
-
- if (!isEmpty && !JoinIntervals(DstInt, SrcInt, Swapped)) {
+ if (SrcInt.empty()) {
+ if (!CanCoalesceWithImpDef(CopyMI, DstInt, SrcInt)) {
+ // Only coalesce an empty interval (defined by implicit_def) with
+ // another interval which has a valno defined by the CopyMI and the CopyMI
+ // is a kill of the implicit def.
+ DEBUG(dbgs() << "\tNot profitable!\n");
+ return false;
+ }
+ } else if (!JoinIntervals(DstInt, SrcInt, Swapped)) {
// Coalescing failed.
// If definition of source is defined by trivial computation, try
(AdjustCopiesBackFrom(SrcInt, DstInt, CopyMI) ||
RemoveCopyByCommutingDef(SrcInt, DstInt, CopyMI))) {
JoinedCopies.insert(CopyMI);
+ DEBUG(dbgs() << "\tTrivial!\n");
return true;
}
// Otherwise, we are unable to join the intervals.
- DEBUG(dbgs() << "Interference!\n");
+ DEBUG(dbgs() << "\tInterference!\n");
Again = true; // May be possible to coalesce later.
return false;
}
// Remember to delete the copy instruction.
JoinedCopies.insert(CopyMI);
- // Some live range has been lengthened due to colaescing, eliminate the
- // unnecessary kills.
- RemoveUnnecessaryKills(SrcReg, *ResDstInt);
- if (TargetRegisterInfo::isVirtualRegister(DstReg))
- RemoveUnnecessaryKills(DstReg, *ResDstInt);
-
UpdateRegDefsUses(SrcReg, DstReg, SubIdx);
// If we have extended the live range of a physical register, make sure we
// Manually deleted the live interval copy.
if (SavedLI) {
SavedLI->clear();
- delete SavedLI;
+ SavedLI.reset();
}
// If resulting interval has a preference that no longer fits because of subreg
}
DEBUG({
- dbgs() << "\n\t\tJoined. Result = ";
+ dbgs() << "\t\tJoined. Result = ";
ResDstInt->print(dbgs(), tri_);
dbgs() << "\n";
});
li_->intervalIsInOneMBB(RHS) &&
li_->getApproximateInstructionCount(RHS) <= 10) {
// Perform a more exhaustive check for some common cases.
- if (li_->conflictsWithPhysRegRef(RHS, LHS.reg, true, JoinedCopies))
+ if (li_->conflictsWithSubPhysRegRef(RHS, LHS.reg, true, JoinedCopies))
return false;
} else {
for (const unsigned* SR = tri_->getSubRegisters(LHS.reg); *SR; ++SR)
if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
DEBUG({
- dbgs() << "Interfere with sub-register ";
+ dbgs() << "\tInterfere with sub-register ";
li_->getInterval(*SR).print(dbgs(), tri_);
});
return false;
if (LHS.containsOneValue() &&
li_->getApproximateInstructionCount(LHS) <= 10) {
// Perform a more exhaustive check for some common cases.
- if (li_->conflictsWithPhysRegRef(LHS, RHS.reg, false, JoinedCopies))
+ if (li_->conflictsWithSubPhysRegRef(LHS, RHS.reg, false, JoinedCopies))
return false;
} else {
for (const unsigned* SR = tri_->getSubRegisters(RHS.reg); *SR; ++SR)
if (li_->hasInterval(*SR) && LHS.overlaps(li_->getInterval(*SR))) {
DEBUG({
- dbgs() << "Interfere with sub-register ";
+ dbgs() << "\tInterfere with sub-register ";
li_->getInterval(*SR).print(dbgs(), tri_);
});
return false;
MachineInstr *UseMI = Use.getParent();
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
- SrcReg == DstReg)
+ SrcReg == DstReg && SrcSubIdx == DstSubIdx)
// Ignore identity copies.
continue;
SlotIndex Idx = li_->getInstructionIndex(UseMI);
// Ignore identity copies.
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (!(tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
- SrcReg == DstReg))
+ SrcReg == DstReg && SrcSubIdx == DstSubIdx))
for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
MachineOperand &Use = MI->getOperand(i);
if (Use.isReg() && Use.isUse() && Use.getReg() &&
return NULL;
}
-void SimpleRegisterCoalescing::printRegName(unsigned reg) const {
- if (TargetRegisterInfo::isPhysicalRegister(reg))
- dbgs() << tri_->getName(reg);
- else
- dbgs() << "%reg" << reg;
-}
-
void SimpleRegisterCoalescing::releaseMemory() {
JoinedCopies.clear();
ReMatCopies.clear();
// delete them later.
DoDelete = false;
}
- if (MI->registerDefIsDead(DstReg)) {
+ if (MI->allDefsAreDead()) {
LiveInterval &li = li_->getInterval(DstReg);
if (!ShortenDeadCopySrcLiveRange(li, MI))
ShortenDeadCopyLiveRange(li, MI);
if (MO.isDead())
continue;
if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
- !mri_->use_empty(Reg)) {
+ !mri_->use_nodbg_empty(Reg)) {
isDead = false;
break;
}
// If the move will be an identity move delete it
bool isMove= tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx);
- if (isMove && SrcReg == DstReg) {
+ if (isMove && SrcReg == DstReg && SrcSubIdx == DstSubIdx) {
if (li_->hasInterval(SrcReg)) {
LiveInterval &RegInt = li_->getInterval(SrcReg);
// If def of this move instruction is dead, remove its live range
li_->RemoveMachineInstrFromMaps(MI);
mii = mbbi->erase(mii);
++numPeep;
- } else {
- ++mii;
+ continue;
+ }
+
+ ++mii;
+
+ // Check for now unnecessary kill flags.
+ if (li_->isNotInMIMap(MI)) continue;
+ SlotIndex UseIdx = li_->getInstructionIndex(MI).getUseIndex();
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isKill()) continue;
+ unsigned reg = MO.getReg();
+ if (!reg || !li_->hasInterval(reg)) continue;
+ LiveInterval &LI = li_->getInterval(reg);
+ const LiveRange *LR = LI.getLiveRangeContaining(UseIdx);
+ if (!LR ||
+ (!LR->valno->isKill(UseIdx.getDefIndex()) &&
+ LR->valno->def != UseIdx.getDefIndex()))
+ MO.setIsKill(false);
}
}
}
projects / oota-llvm.git / blobdiff