diff options
Diffstat (limited to 'lib/CodeGen/LiveIntervalAnalysis.cpp')
| -rw-r--r-- | lib/CodeGen/LiveIntervalAnalysis.cpp | 1058 |
1 files changed, 3 insertions, 1055 deletions
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp index 00c212d4b8..eadd47b009 100644 --- a/lib/CodeGen/LiveIntervalAnalysis.cpp +++ b/lib/CodeGen/LiveIntervalAnalysis.cpp @@ -39,22 +39,15 @@ using namespace llvm; STATISTIC(numIntervals, "Number of original intervals"); STATISTIC(numIntervalsAfter, "Number of intervals after coalescing"); -STATISTIC(numJoins , "Number of interval joins performed"); -STATISTIC(numPeep , "Number of identity moves eliminated after coalescing"); STATISTIC(numFolded , "Number of loads/stores folded into instructions"); -STATISTIC(numAborts , "Number of times interval joining aborted"); char LiveIntervals::ID = 0; namespace { RegisterPass<LiveIntervals> X("liveintervals", "Live Interval Analysis"); - - static cl::opt<bool> - EnableJoining("join-liveintervals", - cl::desc("Coallesce copies (default=true)"), - cl::init(true)); } void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const { + AU.addPreserved<LiveVariables>(); AU.addRequired<LiveVariables>(); AU.addPreservedID(PHIEliminationID); AU.addRequiredID(PHIEliminationID); @@ -67,20 +60,8 @@ void LiveIntervals::releaseMemory() { mi2iMap_.clear(); i2miMap_.clear(); r2iMap_.clear(); - r2rMap_.clear(); - JoinedLIs.clear(); -} - - -static bool isZeroLengthInterval(LiveInterval *li) { - for (LiveInterval::Ranges::const_iterator - i = li->ranges.begin(), e = li->ranges.end(); i != e; ++i) - if (i->end - i->start > LiveIntervals::InstrSlots::NUM) - return false; - return true; } - /// runOnMachineFunction - Register allocate the whole function /// bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) { @@ -89,11 +70,7 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) { mri_ = tm_->getRegisterInfo(); tii_ = tm_->getInstrInfo(); lv_ = &getAnalysis<LiveVariables>(); - r2rMap_.grow(mf_->getSSARegMap()->getLastVirtReg()); allocatableRegs_ = mri_->getAllocatableSet(fn); - for (MRegisterInfo::regclass_iterator I = mri_->regclass_begin(), - E = mri_->regclass_end(); I != E; ++I) - allocatableRCRegs_.insert(std::make_pair(*I,mri_->getAllocatableSet(fn, *I))); // Number MachineInstrs and MachineBasicBlocks. // Initialize MBB indexes to a sentinal. @@ -124,99 +101,7 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) { DOUT << "\n"; } - // Join (coallesce) intervals if requested. - if (EnableJoining) { - joinIntervals(); - DOUT << "********** INTERVALS POST JOINING **********\n"; - for (iterator I = begin(), E = end(); I != E; ++I) { - I->second.print(DOUT, mri_); - DOUT << "\n"; - } - } - numIntervalsAfter += getNumIntervals(); - - // perform a final pass over the instructions and compute spill - // weights, coalesce virtual registers and remove identity moves. - const LoopInfo &loopInfo = getAnalysis<LoopInfo>(); - - for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end(); - mbbi != mbbe; ++mbbi) { - MachineBasicBlock* mbb = mbbi; - unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock()); - - for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end(); - mii != mie; ) { - // if the move will be an identity move delete it - unsigned srcReg, dstReg, RegRep; - if (tii_->isMoveInstr(*mii, srcReg, dstReg) && - (RegRep = rep(srcReg)) == rep(dstReg)) { - // remove from def list - LiveInterval &RegInt = getOrCreateInterval(RegRep); - MachineOperand *MO = mii->findRegisterDefOperand(dstReg); - // If def of this move instruction is dead, remove its live range from - // the dstination register's live interval. - if (MO->isDead()) { - unsigned MoveIdx = getDefIndex(getInstructionIndex(mii)); - LiveInterval::iterator MLR = RegInt.FindLiveRangeContaining(MoveIdx); - RegInt.removeRange(MLR->start, MoveIdx+1); - if (RegInt.empty()) - removeInterval(RegRep); - } - RemoveMachineInstrFromMaps(mii); - mii = mbbi->erase(mii); - ++numPeep; - } else { - SmallSet<unsigned, 4> UniqueUses; - for (unsigned i = 0, e = mii->getNumOperands(); i != e; ++i) { - const MachineOperand &mop = mii->getOperand(i); - if (mop.isRegister() && mop.getReg() && - MRegisterInfo::isVirtualRegister(mop.getReg())) { - // replace register with representative register - unsigned reg = rep(mop.getReg()); - mii->getOperand(i).setReg(reg); - - // Multiple uses of reg by the same instruction. It should not - // contribute to spill weight again. - if (UniqueUses.count(reg) != 0) - continue; - LiveInterval &RegInt = getInterval(reg); - float w = (mop.isUse()+mop.isDef()) * powf(10.0F, (float)loopDepth); - // If the definition instruction is re-materializable, its spill - // weight is half of what it would have been normally unless it's - // a load from fixed stack slot. - int Dummy; - if (RegInt.remat && !tii_->isLoadFromStackSlot(RegInt.remat, Dummy)) - w /= 2; - RegInt.weight += w; - UniqueUses.insert(reg); - } - } - ++mii; - } - } - } - - for (iterator I = begin(), E = end(); I != E; ++I) { - LiveInterval &LI = I->second; - if (MRegisterInfo::isVirtualRegister(LI.reg)) { - // If the live interval length is essentially zero, i.e. in every live - // range the use follows def immediately, it doesn't make sense to spill - // it and hope it will be easier to allocate for this li. - if (isZeroLengthInterval(&LI)) - LI.weight = HUGE_VALF; - - // Slightly prefer live interval that has been assigned a preferred reg. - if (LI.preference) - LI.weight *= 1.01F; - - // Divide the weight of the interval by its size. This encourages - // spilling of intervals that are large and have few uses, and - // discourages spilling of small intervals with many uses. - LI.weight /= LI.getSize(); - } - } - DEBUG(dump()); return true; } @@ -240,6 +125,7 @@ void LiveIntervals::print(std::ostream &O, const Module* ) const { } } +// Not called? /// CreateNewLiveInterval - Create a new live interval with the given live /// ranges. The new live interval will have an infinite spill weight. LiveInterval& @@ -268,7 +154,7 @@ LiveIntervals::CreateNewLiveInterval(const LiveInterval *LI, for (unsigned J = 0, e = MI->getNumOperands(); J != e; ++J) { MachineOperand &MOp = MI->getOperand(J); - if (MOp.isRegister() && rep(MOp.getReg()) == LI->reg) + if (MOp.isRegister() && MOp.getReg() == LI->reg) MOp.setReg(NewVReg); } } @@ -794,944 +680,6 @@ void LiveIntervals::computeIntervals() { } } -/// AdjustCopiesBackFrom - We found a non-trivially-coallescable copy with IntA -/// being the source and IntB being the dest, thus this defines a value number -/// in IntB. If the source value number (in IntA) is defined by a copy from B, -/// see if we can merge these two pieces of B into a single value number, -/// eliminating a copy. For example: -/// -/// A3 = B0 -/// ... -/// B1 = A3 <- this copy -/// -/// In this case, B0 can be extended to where the B1 copy lives, allowing the B1 -/// value number to be replaced with B0 (which simplifies the B liveinterval). -/// -/// This returns true if an interval was modified. -/// -bool LiveIntervals::AdjustCopiesBackFrom(LiveInterval &IntA, LiveInterval &IntB, - MachineInstr *CopyMI) { - unsigned CopyIdx = getDefIndex(getInstructionIndex(CopyMI)); - - // BValNo is a value number in B that is defined by a copy from A. 'B3' in - // the example above. - LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx); - unsigned BValNo = BLR->ValId; - - // Get the location that B is defined at. Two options: either this value has - // an unknown definition point or it is defined at CopyIdx. If unknown, we - // can't process it. - unsigned BValNoDefIdx = IntB.getInstForValNum(BValNo); - if (BValNoDefIdx == ~0U) return false; - assert(BValNoDefIdx == CopyIdx && - "Copy doesn't define the value?"); - - // AValNo is the value number in A that defines the copy, A0 in the example. - LiveInterval::iterator AValLR = IntA.FindLiveRangeContaining(CopyIdx-1); - unsigned AValNo = AValLR->ValId; - - // If AValNo is defined as a copy from IntB, we can potentially process this. - - // Get the instruction that defines this value number. - unsigned SrcReg = IntA.getSrcRegForValNum(AValNo); - if (!SrcReg) return false; // Not defined by a copy. - - // If the value number is not defined by a copy instruction, ignore it. - - // If the source register comes from an interval other than IntB, we can't - // handle this. - if (rep(SrcReg) != IntB.reg) return false; - - // Get the LiveRange in IntB that this value number starts with. - unsigned AValNoInstIdx = IntA.getInstForValNum(AValNo); - LiveInterval::iterator ValLR = IntB.FindLiveRangeContaining(AValNoInstIdx-1); - - // Make sure that the end of the live range is inside the same block as - // CopyMI. - MachineInstr *ValLREndInst = getInstructionFromIndex(ValLR->end-1); - if (!ValLREndInst || - ValLREndInst->getParent() != CopyMI->getParent()) return false; - - // Okay, we now know that ValLR ends in the same block that the CopyMI - // live-range starts. If there are no intervening live ranges between them in - // IntB, we can merge them. - if (ValLR+1 != BLR) return false; - - DOUT << "\nExtending: "; IntB.print(DOUT, mri_); - - // We are about to delete CopyMI, so need to remove it as the 'instruction - // that defines this value #'. - IntB.setValueNumberInfo(BValNo, std::make_pair(~0U, 0)); - - // Okay, we can merge them. We need to insert a new liverange: - // [ValLR.end, BLR.begin) of either value number, then we merge the - // two value numbers. - unsigned FillerStart = ValLR->end, FillerEnd = BLR->start; - IntB.addRange(LiveRange(FillerStart, FillerEnd, BValNo)); - - // If the IntB live range is assigned to a physical register, and if that - // physreg has aliases, - if (MRegisterInfo::isPhysicalRegister(IntB.reg)) { - // Update the liveintervals of sub-registers. - for (const unsigned *AS = mri_->getSubRegisters(IntB.reg); *AS; ++AS) { - LiveInterval &AliasLI = getInterval(*AS); - AliasLI.addRange(LiveRange(FillerStart, FillerEnd, - AliasLI.getNextValue(~0U, 0))); - } - } - - // Okay, merge "B1" into the same value number as "B0". - if (BValNo != ValLR->ValId) - IntB.MergeValueNumberInto(BValNo, ValLR->ValId); - DOUT << " result = "; IntB.print(DOUT, mri_); - DOUT << "\n"; - - // If the source instruction was killing the source register before the - // merge, unset the isKill marker given the live range has been extended. - int UIdx = ValLREndInst->findRegisterUseOperandIdx(IntB.reg, true); - if (UIdx != -1) - ValLREndInst->getOperand(UIdx).unsetIsKill(); - - // Finally, delete the copy instruction. - RemoveMachineInstrFromMaps(CopyMI); - CopyMI->eraseFromParent(); - ++numPeep; - return true; -} - - -/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg, -/// which are the src/dst of the copy instruction CopyMI. This returns true -/// if the copy was successfully coallesced away, or if it is never possible -/// to coallesce this copy, due to register constraints. It returns -/// false if it is not currently possible to coallesce this interval, but -/// it may be possible if other things get coallesced. -bool LiveIntervals::JoinCopy(MachineInstr *CopyMI, - unsigned SrcReg, unsigned DstReg, bool PhysOnly) { - DOUT << getInstructionIndex(CopyMI) << '\t' << *CopyMI; - - // Get representative registers. - unsigned repSrcReg = rep(SrcReg); - unsigned repDstReg = rep(DstReg); - - // If they are already joined we continue. - if (repSrcReg == repDstReg) { - DOUT << "\tCopy already coallesced.\n"; - return true; // Not coallescable. - } - - bool SrcIsPhys = MRegisterInfo::isPhysicalRegister(repSrcReg); - bool DstIsPhys = MRegisterInfo::isPhysicalRegister(repDstReg); - if (PhysOnly && !SrcIsPhys && !DstIsPhys) - // Only joining physical registers with virtual registers in this round. - return true; - - // If they are both physical registers, we cannot join them. - if (SrcIsPhys && DstIsPhys) { - DOUT << "\tCan not coallesce physregs.\n"; - return true; // Not coallescable. - } - - // We only join virtual registers with allocatable physical registers. - if (SrcIsPhys && !allocatableRegs_[repSrcReg]) { - DOUT << "\tSrc reg is unallocatable physreg.\n"; - return true; // Not coallescable. - } - if (DstIsPhys && !allocatableRegs_[repDstReg]) { - DOUT << "\tDst reg is unallocatable physreg.\n"; - return true; // Not coallescable. - } - - // If they are not of the same register class, we cannot join them. - if (differingRegisterClasses(repSrcReg, repDstReg)) { - DOUT << "\tSrc/Dest are different register classes.\n"; - return true; // Not coallescable. - } - - LiveInterval &SrcInt = getInterval(repSrcReg); - LiveInterval &DstInt = getInterval(repDstReg); - assert(SrcInt.reg == repSrcReg && DstInt.reg == repDstReg && - "Register mapping is horribly broken!"); - - DOUT << "\t\tInspecting "; SrcInt.print(DOUT, mri_); - DOUT << " and "; DstInt.print(DOUT, mri_); - DOUT << ": "; - - // Check if it is necessary to propagate "isDead" property before intervals - // are joined. - MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg); - bool isDead = mopd->isDead(); - bool isShorten = false; - unsigned SrcStart = 0, RemoveStart = 0; - unsigned SrcEnd = 0, RemoveEnd = 0; - if (isDead) { - unsigned CopyIdx = getInstructionIndex(CopyMI); - LiveInterval::iterator SrcLR = - SrcInt.FindLiveRangeContaining(getUseIndex(CopyIdx)); - RemoveStart = SrcStart = SrcLR->start; - RemoveEnd = SrcEnd = SrcLR->end; - // The instruction which defines the src is only truly dead if there are - // no intermediate uses and there isn't a use beyond the copy. - // FIXME: find the last use, mark is kill and shorten the live range. - if (SrcEnd > getDefIndex(CopyIdx)) { - isDead = false; - } else { - MachineOperand *MOU; - MachineInstr *LastUse= lastRegisterUse(SrcStart, CopyIdx, repSrcReg, MOU); - if (LastUse) { - // Shorten the liveinterval to the end of last use. - MOU->setIsKill(); - isDead = false; - isShorten = true; - RemoveStart = getDefIndex(getInstructionIndex(LastUse)); - RemoveEnd = SrcEnd; - } else { - MachineInstr *SrcMI = getInstructionFromIndex(SrcStart); - if (SrcMI) { - MachineOperand *mops = findDefOperand(SrcMI, repSrcReg); - if (mops) - // A dead def should have a single cycle interval. - ++RemoveStart; - } - } - } - } - - // We need to be careful about coalescing a source physical register with a - // virtual register. Once the coalescing is done, it cannot be broken and - // these are not spillable! If the destination interval uses are far away, - // think twice about coalescing them! - if (!mopd->isDead() && (SrcIsPhys || DstIsPhys)) { - LiveInterval &JoinVInt = SrcIsPhys ? DstInt : SrcInt; - unsigned JoinVReg = SrcIsPhys ? repDstReg : repSrcReg; - unsigned JoinPReg = SrcIsPhys ? repSrcReg : repDstReg; - const TargetRegisterClass *RC = mf_->getSSARegMap()->getRegClass(JoinVReg); - unsigned Threshold = allocatableRCRegs_[RC].count(); - - // If the virtual register live interval is long has it has low use desity, - // do not join them, instead mark the physical register as its allocation - // preference. - unsigned Length = JoinVInt.getSize() / InstrSlots::NUM; - LiveVariables::VarInfo &vi = lv_->getVarInfo(JoinVReg); - if (Length > Threshold && - (((float)vi.NumUses / Length) < (1.0 / Threshold))) { - JoinVInt.preference = JoinPReg; - ++numAborts; - DOUT << "\tMay tie down a physical register, abort!\n"; - return false; - } - } - - // Okay, attempt to join these two intervals. On failure, this returns false. - // Otherwise, if one of the intervals being joined is a physreg, this method - // always canonicalizes DstInt to be it. The output "SrcInt" will not have - // been modified, so we can use this information below to update aliases. - if (JoinIntervals(DstInt, SrcInt)) { - if (isDead) { - // Result of the copy is dead. Propagate this property. - if (SrcStart == 0) { - assert(MRegisterInfo::isPhysicalRegister(repSrcReg) && - "Live-in must be a physical register!"); - // Live-in to the function but dead. Remove it from entry live-in set. - // JoinIntervals may end up swapping the two intervals. - mf_->begin()->removeLiveIn(repSrcReg); - } else { - MachineInstr *SrcMI = getInstructionFromIndex(SrcStart); - if (SrcMI) { - MachineOperand *mops = findDefOperand(SrcMI, repSrcReg); - if (mops) - mops->setIsDead(); - } - } - } - - if (isShorten || isDead) { - // Shorten the live interval. - LiveInterval &LiveInInt = (repSrcReg == DstInt.reg) ? DstInt : SrcInt; - LiveInInt.removeRange(RemoveStart, RemoveEnd); - } - } else { - // Coallescing failed. - - // If we can eliminate the copy without merging the live ranges, do so now. - if (AdjustCopiesBackFrom(SrcInt, DstInt, CopyMI)) - return true; - - // Otherwise, we are unable to join the intervals. - DOUT << "Interference!\n"; - return false; - } - - bool Swapped = repSrcReg == DstInt.reg; - if (Swapped) - std::swap(repSrcReg, repDstReg); - assert(MRegisterInfo::isVirtualRegister(repSrcReg) && - "LiveInterval::join didn't work right!"); - - // If we're about to merge live ranges into a physical register live range, - // we have to update any aliased register's live ranges to indicate that they - // have clobbered values for this range. - if (MRegisterInfo::isPhysicalRegister(repDstReg)) { - // Unset unnecessary kills. - if (!DstInt.containsOneValue()) { - for (LiveInterval::Ranges::const_iterator I = SrcInt.begin(), - E = SrcInt.end(); I != E; ++I) - unsetRegisterKills(I->start, I->end, repDstReg); - } - - // Update the liveintervals of sub-registers. - for (const unsigned *AS = mri_->getSubRegisters(repDstReg); *AS; ++AS) - getInterval(*AS).MergeInClobberRanges(SrcInt); - } else { - // Merge use info if the destination is a virtual register. - LiveVariables::VarInfo& dVI = lv_->getVarInfo(repDstReg); - LiveVariables::VarInfo& sVI = lv_->getVarInfo(repSrcReg); - dVI.NumUses += sVI.NumUses; - } - - DOUT << "\n\t\tJoined. Result = "; DstInt.print(DOUT, mri_); - DOUT << "\n"; - - // Remember these liveintervals have been joined. - JoinedLIs.set(repSrcReg - MRegisterInfo::FirstVirtualRegister); - if (MRegisterInfo::isVirtualRegister(repDstReg)) - JoinedLIs.set(repDstReg - MRegisterInfo::FirstVirtualRegister); - - // If the intervals were swapped by Join, swap them back so that the register - // mapping (in the r2i map) is correct. - if (Swapped) SrcInt.swap(DstInt); - removeInterval(repSrcReg); - r2rMap_[repSrcReg] = repDstReg; - - // Finally, delete the copy instruction. - RemoveMachineInstrFromMaps(CopyMI); - CopyMI->eraseFromParent(); - ++numPeep; - ++numJoins; - return true; -} - -/// ComputeUltimateVN - Assuming we are going to join two live intervals, -/// compute what the resultant value numbers for each value in the input two -/// ranges will be. This is complicated by copies between the two which can -/// and will commonly cause multiple value numbers to be merged into one. -/// -/// VN is the value number that we're trying to resolve. InstDefiningValue -/// keeps track of the new InstDefiningValue assignment for the result -/// LiveInterval. ThisFromOther/OtherFromThis are sets that keep track of -/// whether a value in this or other is a copy from the opposite set. -/// ThisValNoAssignments/OtherValNoAssignments keep track of value #'s that have -/// already been assigned. -/// -/// ThisFromOther[x] - If x is defined as a copy from the other interval, this -/// contains the value number the copy is from. -/// -static unsigned ComputeUltimateVN(unsigned VN, - SmallVector<std::pair<unsigned, - unsigned>, 16> &ValueNumberInfo, - SmallVector<int, 16> &ThisFromOther, - SmallVector<int, 16> &OtherFromThis, - SmallVector<int, 16> &ThisValNoAssignments, - SmallVector<int, 16> &OtherValNoAssignments, - LiveInterval &ThisLI, LiveInterval &OtherLI) { - // If the VN has already been computed, just return it. - if (ThisValNoAssignments[VN] >= 0) - return ThisValNoAssignments[VN]; -// assert(ThisValNoAssignments[VN] != -2 && "Cyclic case?"); - - // If this val is not a copy from the other val, then it must be a new value - // number in the destination. - int OtherValNo = ThisFromOther[VN]; - if (OtherValNo == -1) { - ValueNumberInfo.push_back(ThisLI.getValNumInfo(VN)); - return ThisValNoAssignments[VN] = ValueNumberInfo.size()-1; - } - - // Otherwise, this *is* a copy from the RHS. If the other side has already - // been computed, return it. - if (OtherValNoAssignments[OtherValNo] >= 0) - return ThisValNoAssignments[VN] = OtherValNoAssignments[OtherValNo]; - - // Mark this value number as currently being computed, then ask what the - // ultimate value # of the other value is. - ThisValNoAssignments[VN] = -2; - unsigned UltimateVN = - ComputeUltimateVN(OtherValNo, ValueNumberInfo, - OtherFromThis, ThisFromOther, - OtherValNoAssignments, ThisValNoAssignments, - OtherLI, ThisLI); - return ThisValNoAssignments[VN] = UltimateVN; -} - -static bool InVector(unsigned Val, const SmallVector<unsigned, 8> &V) { - return std::find(V.begin(), V.end(), Val) != V.end(); -} - -/// SimpleJoin - Attempt to joint the specified interval into this one. The -/// caller of this method must guarantee that the RHS only contains a single -/// value number and that the RHS is not defined by a copy from this -/// interval. This returns false if the intervals are not joinable, or it -/// joins them and returns true. -bool LiveIntervals::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS) { - assert(RHS.containsOneValue()); - - // Some number (potentially more than one) value numbers in the current - // interval may be defined as copies from the RHS. Scan the overlapping - // portions of the LHS and RHS, keeping track of this and looking for - // overlapping live ranges that are NOT defined as copies. If these exist, we - // cannot coallesce. - - LiveInterval::iterator LHSIt = LHS.begin(), LHSEnd = LHS.end(); - LiveInterval::iterator RHSIt = RHS.begin(), RHSEnd = RHS.end(); - - if (LHSIt->start < RHSIt->start) { - LHSIt = std::upper_bound(LHSIt, LHSEnd, RHSIt->start); - if (LHSIt != LHS.begin()) --LHSIt; - } else if (RHSIt->start < LHSIt->start) { - RHSIt = std::upper_bound(RHSIt, RHSEnd, LHSIt->start); - if (RHSIt != RHS.begin()) --RHSIt; - } - - SmallVector<unsigned, 8> EliminatedLHSVals; - - while (1) { - // Determine if these live intervals overlap. - bool Overlaps = false; - if (LHSIt->start <= RHSIt->start) - Overlaps = LHSIt->end > RHSIt->start; - else - Overlaps = RHSIt->end > LHSIt->start; - - // If the live intervals overlap, there are two interesting cases: if the - // LHS interval is defined by a copy from the RHS, it's ok and we record - // that the LHS value # is the same as the RHS. If it's not, then we cannot - // coallesce these live ranges and we bail out. - if (Overlaps) { - // If we haven't already recorded that this value # is safe, check it. - if (!InVector(LHSIt->ValId, EliminatedLHSVals)) { - // Copy from the RHS? - unsigned SrcReg = LHS.getSrcRegForValNum(LHSIt->ValId); - if (rep(SrcReg) != RHS.reg) - return false; // Nope, bail out. - - EliminatedLHSVals.push_back(LHSIt->ValId); - } - - // We know this entire LHS live range is okay, so skip it now. - if (++LHSIt == LHSEnd) break; - continue; - } - - if (LHSIt->end < RHSIt->end) { - if (++LHSIt == LHSEnd) break; - } else { - // One interesting case to check here. It's possible that we have - // something like "X3 = Y" which defines a new value number in the LHS, - // and is the last use of this liverange of the RHS. In this case, we - // want to notice this copy (so that it gets coallesced away) even though - // the live ranges don't actually overlap. - if (LHSIt->start == RHSIt->end) { - if (InVector(LHSIt->ValId, EliminatedLHSVals)) { - // We already know that this value number is going to be merged in - // if coallescing succeeds. Just skip the liverange. - if (++LHSIt == LHSEnd) break; - } else { - // Otherwise, if this is a copy from the RHS, mark it as being merged - // in. - if (rep(LHS.getSrcRegForValNum(LHSIt->ValId)) == RHS.reg) { - EliminatedLHSVals.push_back(LHSIt->ValId); - - // We know this entire LHS live range is okay, so skip it now. - if (++LHSIt == LHSEnd) break; - } - } - } - - if (++RHSIt == RHSEnd) break; - } - } - - // If we got here, we know that the coallescing will be successful and that - // the value numbers in EliminatedLHSVals will all be merged together. Since - // the most common case is that EliminatedLHSVals has a single number, we - // optimize for it: if there is more than one value, we merge them all into - // the lowest numbered one, then handle the interval as if we were merging - // with one value number. - unsigned LHSValNo; - if (EliminatedLHSVals.size() > 1) { - // Loop through all the equal value numbers merging them into the smallest - // one. - unsigned Smallest = EliminatedLHSVals[0]; - for (unsigned i = 1, e = EliminatedLHSVals.size(); i != e; ++i) { - if (EliminatedLHSVals[i] < Smallest) { - // Merge the current notion of the smallest into the smaller one. - LHS.MergeValueNumberInto(Smallest, EliminatedLHSVals[i]); - Smallest = EliminatedLHSVals[i]; - } else { - // Merge into the smallest. - LHS.MergeValueNumberInto(EliminatedLHSVals[i], Smallest); - } - } - LHSValNo = Smallest; - } else { - assert(!EliminatedLHSVals.empty() && "No copies from the RHS?"); - LHSValNo = EliminatedLHSVals[0]; - } - - // Okay, now that there is a single LHS value number that we're merging the - // RHS into, update the value number info for the LHS to indicate that the - // value number is defined where the RHS value number was. - LHS.setValueNumberInfo(LHSValNo, RHS.getValNumInfo(0)); - - // Okay, the final step is to loop over the RHS live intervals, adding them to - // the LHS. - LHS.MergeRangesInAsValue(RHS, LHSValNo); - LHS.weight += RHS.weight; - if (RHS.preference && !LHS.preference) - LHS.preference = RHS.preference; - - return true; -} - -/// JoinIntervals - Attempt to join these two intervals. On failure, this -/// returns false. Otherwise, if one of the intervals being joined is a -/// physreg, this method always canonicalizes LHS to be it. The output -/// "RHS" will not have been modified, so we can use this information -/// below to update aliases. -bool LiveIntervals::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS) { - // Compute the final value assignment, assuming that the live ranges can be - // coallesced. - SmallVector<int, 16> LHSValNoAssignments; - SmallVector<int, 16> RHSValNoAssignments; - SmallVector<std::pair<unsigned,unsigned>, 16> ValueNumberInfo; - - // If a live interval is a physical register, conservatively check if any - // of its sub-registers is overlapping the live interval of the virtual - // register. If so, do not coalesce. - if (MRegisterInfo::isPhysicalRegister(LHS.reg) && - *mri_->getSubRegisters(LHS.reg)) { - for (const unsigned* SR = mri_->getSubRegisters(LHS.reg); *SR; ++SR) - if (hasInterval(*SR) && RHS.overlaps(getInterval(*SR))) { - DOUT << "Interfere with sub-register "; - DEBUG(getInterval(*SR).print(DOUT, mri_)); - return false; - } - } else if (MRegisterInfo::isPhysicalRegister(RHS.reg) && - *mri_->getSubRegisters(RHS.reg)) { - for (const unsigned* SR = mri_->getSubRegisters(RHS.reg); *SR; ++SR) - if (hasInterval(*SR) && LHS.overlaps(getInterval(*SR))) { - DOUT << "Interfere with sub-register "; - DEBUG(getInterval(*SR).print(DOUT, mri_)); - return false; - } - } - - // Compute ultimate value numbers for the LHS and RHS values. - if (RHS.containsOneValue()) { - // Copies from a liveinterval with a single value are simple to handle and - // very common, handle the special case here. This is important, because - // often RHS is small and LHS is large (e.g. a physreg). - - // Find out if the RHS is defined as a copy from some value in the LHS. - int RHSValID = -1; - std::pair<unsigned,unsigned> RHSValNoInfo; - unsigned RHSSrcReg = RHS.getSrcRegForValNum(0); - if ((RHSSrcReg == 0 || rep(RHSSrcReg) != LHS.reg)) { - // If RHS is not defined as a copy from the LHS, we can use simpler and - // faster checks to see if the live ranges are coallescable. This joiner - // can't swap the LHS/RHS intervals though. - if (!MRegisterInfo::isPhysicalRegister(RHS.reg)) { - return SimpleJoin(LHS, RHS); - } else { - RHSValNoInfo = RHS.getValNumInfo(0); - } - } else { - // It was defined as a copy from the LHS, find out what value # it is. - unsigned ValInst = RHS.getInstForValNum(0); - RHSValID = LHS.getLiveRangeContaining(ValInst-1)->ValId; - RHSValNoInfo = LHS.getValNumInfo(RHSValID); - } - - LHSValNoAssignments.resize(LHS.getNumValNums(), -1); - RHSValNoAssignments.resize(RHS.getNumValNums(), -1); - ValueNumberInfo.resize(LHS.getNumValNums()); - - // Okay, *all* of the values in LHS that are defined as a copy from RHS - // should now get updated. - for (unsigned VN = 0, e = LHS.getNumValNums(); VN != e; ++VN) { - if (unsigned LHSSrcReg = LHS.getSrcRegForValNum(VN)) { - if (rep(LHSSrcReg) != RHS.reg) { - // If this is not a copy from the RHS, its value number will be - // unmodified by the coallescing. - ValueNumberInfo[VN] = LHS.getValNumInfo(VN); - LHSValNoAssignments[VN] = VN; - } else if (RHSValID == -1) { - // Otherwise, it is a copy from the RHS, and we don't already have a - // value# for it. Keep the current value number, but remember it. - LHSValNoAssignments[VN] = RHSValID = VN; - ValueNumberInfo[VN] = RHSValNoInfo; - } else { - // Otherwise, use the specified value #. - LHSValNoAssignments[VN] = RHSValID; - if (VN != (unsigned)RHSValID) - ValueNumberInfo[VN].first = ~1U; - else - ValueNumberInfo[VN] = RHSValNoInfo; - } - } else { - ValueNumberInfo[VN] = LHS.getValNumInfo(VN); - LHSValNoAssignments[VN] = VN; - } - } - - assert(RHSValID != -1 && "Didn't find value #?"); - RHSValNoAssignments[0] = RHSValID; - - } else { - // Loop over the value numbers of the LHS, seeing if any are defined from - // the RHS. - SmallVector<int, 16> LHSValsDefinedFromRHS; - LHSValsDefinedFromRHS.resize(LHS.getNumValNums(), -1); - for (unsigned VN = 0, e = LHS.getNumValNums(); VN != e; ++VN) { - unsigned ValSrcReg = LHS.getSrcRegForValNum(VN); - if (ValSrcReg == 0) // Src not defined by a copy? - continue; - - // DstReg is known to be a register in the LHS interval. If the src is - // from the RHS interval, we can use its value #. - if (rep(ValSrcReg) != RHS.reg) - continue; - - // Figure out the value # from the RHS. - unsigned ValInst = LHS.getInstForValNum(VN); - LHSValsDefinedFromRHS[VN] = RHS.getLiveRangeContaining(ValInst-1)->ValId; - } - - // Loop over the value numbers of the RHS, seeing if any are defined from - // the LHS. - SmallVector<int, 16> RHSValsDefinedFromLHS; - RHSValsDefinedFromLHS.resize(RHS.getNumValNums(), -1); - for (unsigned VN = 0, e = RHS.getNumValNums(); VN != e; ++VN) { - unsigned ValSrcReg = RHS.getSrcRegForValNum(VN); - if (ValSrcReg == 0) // Src not defined by a copy? - continue; - - // DstReg is known to be a register in the RHS interval. If the src is - // from the LHS interval, we can use its value #. - if (rep(ValSrcReg) != LHS.reg) - continue; - - // Figure out the value # from the LHS. - unsigned ValInst = RHS.getInstForValNum(VN); - RHSValsDefinedFromLHS[VN] = LHS.getLiveRangeContaining(ValInst-1)->ValId; - } - - LHSValNoAssignments.resize(LHS.getNumValNums(), -1); - RHSValNoAssignments.resize(RHS.getNumValNums(), -1); - ValueNumberInfo.reserve(LHS.getNumValNums() + RHS.getNumValNums()); - - for (unsigned VN = 0, e = LHS.getNumValNums(); VN != e; ++VN) { - if (LHSValNoAssignments[VN] >= 0 || LHS.getInstForValNum(VN) == ~2U) - continue; - ComputeUltimateVN(VN, ValueNumberInfo, - LHSValsDefinedFromRHS, RHSValsDefinedFromLHS, - LHSValNoAssignments, RHSValNoAssignments, LHS, RHS); - } - for (unsigned VN = 0, e = RHS.getNumValNums(); VN != e; ++VN) { - if (RHSValNoAssignments[VN] >= 0 || RHS.getInstForValNum(VN) == ~2U) - continue; - // If this value number isn't a copy from the LHS, it's a new number. - if (RHSValsDefinedFromLHS[VN] == -1) { - ValueNumberInfo.push_back(RHS.getValNumInfo(VN)); - RHSValNoAssignments[VN] = ValueNumberInfo.size()-1; - continue; - } - - ComputeUltimateVN(VN, ValueNumberInfo, - RHSValsDefinedFromLHS, LHSValsDefinedFromRHS, - RHSValNoAssignments, LHSValNoAssignments, RHS, LHS); - } - } - - // Armed with the mappings of LHS/RHS values to ultimate values, walk the - // interval lists to see if these intervals are coallescable. - LiveInterval::const_iterator I = LHS.begin(); - LiveInterval::const_iterator IE = LHS.end(); - LiveInterval::const_iterator J = RHS.begin(); - LiveInterval::const_iterator JE = RHS.end(); - - // Skip ahead until the first place of potential sharing. - if (I->start < J->start) { - I = std::upper_bound(I, IE, J->start); - if (I != LHS.begin()) --I; - } else if (J->start < I->start) { - J = std::upper_bound(J, JE, I->start); - if (J != RHS.begin()) --J; - } - - while (1) { - // Determine if these two live ranges overlap. - bool Overlaps; - if (I->start < J->start) { - Overlaps = I->end > J->start; - } else { - Overlaps = J->end > I->start; - } - - // If so, check value # info to determine if they are really different. - if (Overlaps) { - // If the live range overlap will map to the same value number in the - // result liverange, we can still coallesce them. If not, we can't. - if (LHSValNoAssignments[I->ValId] != RHSValNoAssignments[J->ValId]) - return false; - } - - if (I->end < J->end) { - ++I; - if (I == IE) break; - } else { - ++J; - if (J == JE) break; - } - } - - // If we get here, we know that we can coallesce the live ranges. Ask the - // intervals to coallesce themselves now. - LHS.join(RHS, &LHSValNoAssignments[0], &RHSValNoAssignments[0], - ValueNumberInfo); - return true; -} - - -namespace { - // DepthMBBCompare - Comparison predicate that sort first based on the loop - // depth of the basic block (the unsigned), and then on the MBB number. - struct DepthMBBCompare { - typedef std::pair<unsigned, MachineBasicBlock*> DepthMBBPair; - bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const { - if (LHS.first > RHS.first) return true; // Deeper loops first - return LHS.first == RHS.first && - LHS.second->getNumber() < RHS.second->getNumber(); - } - }; -} - - -void LiveIntervals::CopyCoallesceInMBB(MachineBasicBlock *MBB, - std::vector<CopyRec> *TryAgain, bool PhysOnly) { - DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n"; - - for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end(); - MII != E;) { - MachineInstr *Inst = MII++; - - // If this isn't a copy, we can't join intervals. - unsigned SrcReg, DstReg; - if (!tii_->isMoveInstr(*Inst, SrcReg, DstReg)) continue; - - if (TryAgain && !JoinCopy(Inst, SrcReg, DstReg, PhysOnly)) - TryAgain->push_back(getCopyRec(Inst, SrcReg, DstReg)); - } -} - - -void LiveIntervals::joinIntervals() { - DOUT << "********** JOINING INTERVALS ***********\n"; - - JoinedLIs.resize(getNumIntervals()); - JoinedLIs.reset(); - - std::vector<CopyRec> TryAgainList; - const LoopInfo &LI = getAnalysis<LoopInfo>(); - if (LI.begin() == LI.end()) { - // If there are no loops in the function, join intervals in function order. - for (MachineFunction::iterator I = mf_->begin(), E = mf_->end(); - I != E; ++I) - CopyCoallesceInMBB(I, &TryAgainList); - } else { - // Otherwise, join intervals in inner loops before other intervals. - // Unfortunately we can't just iterate over loop hierarchy here because - // there may be more MBB's than BB's. Collect MBB's for sorting. - - // Join intervals in the function prolog first. We want to join physical - // registers with virtual registers before the intervals got too long. - std::vector<std::pair<unsigned, MachineBasicBlock*> > MBBs; - for (MachineFunction::iterator I = mf_->begin(), E = mf_->end(); I != E;++I) - MBBs.push_back(std::make_pair(LI.getLoopDepth(I->getBasicBlock()), I)); - - // Sort by loop depth. - std::sort(MBBs.begin(), MBBs.end(), DepthMBBCompare()); - - // Finally, join intervals in loop nest order. - for (unsigned i = 0, e = MBBs.size(); i != e; ++i) - CopyCoallesceInMBB(MBBs[i].second, NULL, true); - for (unsigned i = 0, e = MBBs.size(); i != e; ++i) - CopyCoallesceInMBB(MBBs[i].second, &TryAgainList, false); - } - - // Joining intervals can allow other intervals to be joined. Iteratively join - // until we make no progress. - bool ProgressMade = true; - while (ProgressMade) { - ProgressMade = false; - - for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) { - CopyRec &TheCopy = TryAgainList[i]; - if (TheCopy.MI && - JoinCopy(TheCopy.MI, TheCopy.SrcReg, TheCopy.DstReg)) { - TheCopy.MI = 0; // Mark this one as done. - ProgressMade = true; - } - } - } - - // Some live range has been lengthened due to colaescing, eliminate the - // unnecessary kills. - int RegNum = JoinedLIs.find_first(); - while (RegNum != -1) { - unsigned Reg = RegNum + MRegisterInfo::FirstVirtualRegister; - unsigned repReg = rep(Reg); - LiveInterval &LI = getInterval(repReg); - LiveVariables::VarInfo& svi = lv_->getVarInfo(Reg); - for (unsigned i = 0, e = svi.Kills.size(); i != e; ++i) { - MachineInstr *Kill = svi.Kills[i]; - // Suppose vr1 = op vr2, x - // and vr1 and vr2 are coalesced. vr2 should still be marked kill - // unless it is a two-address operand. - if (isRemoved(Kill) || hasRegisterDef(Kill, repReg)) - continue; - if (LI.liveAt(getInstructionIndex(Kill) + InstrSlots::NUM)) - unsetRegisterKill(Kill, repReg); - } - RegNum = JoinedLIs.find_next(RegNum); - } - - DOUT << "*** Register mapping ***\n"; - for (int i = 0, e = r2rMap_.size(); i != e; ++i) - if (r2rMap_[i]) { - DOUT << " reg " << i << " -> "; - DEBUG(printRegName(r2rMap_[i])); - DOUT << "\n"; - } -} - -/// Return true if the two specified registers belong to different register -/// classes. The registers may be either phys or virt regs. -bool LiveIntervals::differingRegisterClasses(unsigned RegA, - unsigned RegB) const { - - // Get the register classes for the first reg. - if (MRegisterInfo::isPhysicalRegister(RegA)) { - assert(MRegisterInfo::isVirtualRegister(RegB) && - "Shouldn't consider two physregs!"); - return !mf_->getSSARegMap()->getRegClass(RegB)->contains(RegA); - } - - // Compare against the regclass for the second reg. - const TargetRegisterClass *RegClass = mf_->getSSARegMap()->getRegClass(RegA); - if (MRegisterInfo::isVirtualRegister(RegB)) - return RegClass != mf_->getSSARegMap()->getRegClass(RegB); - else - return !RegClass->contains(RegB); -} - -/// lastRegisterUse - Returns the last use of the specific register between -/// cycles Start and End. It also returns the use operand by reference. It -/// returns NULL if there are no uses. -MachineInstr * -LiveIntervals::lastRegisterUse(unsigned Start, unsigned End, unsigned Reg, - MachineOperand *&MOU) { - int e = (End-1) / InstrSlots::NUM * InstrSlots::NUM; - int s = Start; - while (e >= s) { - // Skip deleted instructions - MachineInstr *MI = getInstructionFromIndex(e); - while ((e - InstrSlots::NUM) >= s && !MI) { - e -= InstrSlots::NUM; - MI = getInstructionFromIndex(e); - } - if (e < s || MI == NULL) - return NULL; - - for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (MO.isReg() && MO.isUse() && MO.getReg() && - mri_->regsOverlap(rep(MO.getReg()), Reg)) { - MOU = &MO; - return MI; - } - } - - e -= InstrSlots::NUM; - } - - return NULL; -} - - -/// findDefOperand - Returns the MachineOperand that is a def of the specific -/// register. It returns NULL if the def is not found. -MachineOperand *LiveIntervals::findDefOperand(MachineInstr *MI, unsigned Reg) { - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (MO.isReg() && MO.isDef() && - mri_->regsOverlap(rep(MO.getReg()), Reg)) - return &MO; - } - return NULL; -} - -/// unsetRegisterKill - Unset IsKill property of all uses of specific register -/// of the specific instruction. -void LiveIntervals::unsetRegisterKill(MachineInstr *MI, unsigned Reg) { - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (MO.isReg() && MO.isUse() && MO.isKill() && MO.getReg() && - mri_->regsOverlap(rep(MO.getReg()), Reg)) - MO.unsetIsKill(); - } -} - -/// unsetRegisterKills - Unset IsKill property of all uses of specific register -/// between cycles Start and End. -void LiveIntervals::unsetRegisterKills(unsigned Start, unsigned End, - unsigned Reg) { - int e = (End-1) / InstrSlots::NUM * InstrSlots::NUM; - int s = Start; - while (e >= s) { - // Skip deleted instructions - MachineInstr *MI = getInstructionFromIndex(e); - while ((e - InstrSlots::NUM) >= s && !MI) { - e -= InstrSlots::NUM; - MI = getInstructionFromIndex(e); - } - if (e < s || MI == NULL) - return; - - for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (MO.isReg() && MO.isUse() && MO.isKill() && MO.getReg() && - mri_->regsOverlap(rep(MO.getReg()), Reg)) { - MO.unsetIsKill(); - } - } - - e -= InstrSlots::NUM; - } -} - -/// hasRegisterDef - True if the instruction defines the specific register. -/// -bool LiveIntervals::hasRegisterDef(MachineInstr *MI, unsigned Reg) { - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (MO.isReg() && MO.isDef() && - mri_->regsOverlap(rep(MO.getReg()), Reg)) - return true; - } - return false; -} - LiveInterval LiveIntervals::createInterval(unsigned reg) { float Weight = MRegisterInfo::isPhysicalRegister(reg) ? HUGE_VALF : 0.0F; |