-/// 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)) {
- for (const unsigned *AS = mri_->getAliasSet(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->findRegisterUseOperand(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 these 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) {
- 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.
- }
-
- // If they are both physical registers, we cannot join them.
- if (MRegisterInfo::isPhysicalRegister(repSrcReg) &&
- MRegisterInfo::isPhysicalRegister(repDstReg)) {
- DOUT << "\tCan not coallesce physregs.\n";
- return true; // Not coallescable.
- }
-
- // We only join virtual registers with allocatable physical registers.
- if (MRegisterInfo::isPhysicalRegister(repSrcReg) &&
- !allocatableRegs_[repSrcReg]) {
- DOUT << "\tSrc reg is unallocatable physreg.\n";
- return true; // Not coallescable.
- }
- if (MRegisterInfo::isPhysicalRegister(repDstReg) &&
- !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 &DestInt = getInterval(repDstReg);
- assert(SrcInt.reg == repSrcReg && DestInt.reg == repDstReg &&
- "Register mapping is horribly broken!");
-
- DOUT << "\t\tInspecting "; SrcInt.print(DOUT, mri_);
- DOUT << " and "; DestInt.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(repSrcReg, SrcStart, CopyIdx, MOU);
- if (LastUse) {
- // Shorten the liveinterval to the end of last use.
- MOU->setIsKill();
- isDead = false;
- isShorten = true;
- RemoveStart = getDefIndex(getInstructionIndex(LastUse));
- RemoveEnd = SrcEnd;
- }
- }
- }
-
- // 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() && MRegisterInfo::isPhysicalRegister(repSrcReg)) {
- // Small function. No need to worry!
- unsigned Threshold = allocatableRegs_.count() * 2;
- if (r2iMap_.size() <= Threshold)
- goto TryJoin;
-
- LiveVariables::VarInfo& dvi = lv_->getVarInfo(repDstReg);
- // Is the value used in the current BB or any immediate successroe BB?
- MachineBasicBlock *CopyBB = CopyMI->getParent();
- if (dvi.UsedBlocks[CopyBB->getNumber()])
- goto TryJoin;
- for (MachineBasicBlock::succ_iterator SI = CopyBB->succ_begin(),
- SE = CopyBB->succ_end(); SI != SE; ++SI) {
- MachineBasicBlock *SuccMBB = *SI;
- if (dvi.UsedBlocks[SuccMBB->getNumber()])
- goto TryJoin;
- }
-
- // Ok, no use in this BB and no use in immediate successor BB's. Be really
- // careful now!
- // It's only used in one BB, forget about it!
- if (dvi.UsedBlocks.count() < 2) {
- ++numAborts;
- return false;
- }
-
- // Determine whether to allow coalescing based on how far the closest
- // use is.
- unsigned CopyIdx = getInstructionIndex(CopyMI);
- unsigned MinDist = i2miMap_.size() * InstrSlots::NUM;
- int UseBBNum = dvi.UsedBlocks.find_first();
- while (UseBBNum != -1) {
- MachineBasicBlock *UseBB = mf_->getBlockNumbered(UseBBNum);
- unsigned UseIdx = getMBBStartIdx(UseBB);
- if (UseIdx > CopyIdx) {
- MinDist = std::min(MinDist, UseIdx - CopyIdx);
- if (MinDist <= Threshold)
- break;
- }
- UseBBNum = dvi.UsedBlocks.find_next(UseBBNum);
- }
- if (MinDist > Threshold) {
- // Don't do it!
- ++numAborts;
- return false;
- }
- }
-
-TryJoin:
- // 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 DestInt to be it. The output "SrcInt" will not have
- // been modified, so we can use this information below to update aliases.
- if (JoinIntervals(DestInt, 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 = SrcMI->findRegisterDefOperand(SrcReg);
- if (mops)
- // FIXME: mops == NULL means SrcMI defines a subregister?
- mops->setIsDead();
- }
- }
- }
-
- if (isShorten || isDead) {
- // Shorten the live interval.
- LiveInterval &LiveInInt = (repSrcReg == DestInt.reg) ? DestInt : 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, DestInt, CopyMI))
- return true;
-
- // Otherwise, we are unable to join the intervals.
- DOUT << "Interference!\n";
- return false;
- }
-
- bool Swapped = repSrcReg == DestInt.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)) {
- for (const unsigned *AS = mri_->getAliasSet(repDstReg); *AS; ++AS)
- getInterval(*AS).MergeInClobberRanges(SrcInt);
- } else {
- // Merge UsedBlocks info if the destination is a virtual register.
- LiveVariables::VarInfo& dVI = lv_->getVarInfo(repDstReg);
- LiveVariables::VarInfo& sVI = lv_->getVarInfo(repSrcReg);
- dVI.UsedBlocks |= sVI.UsedBlocks;
- }
-
- DOUT << "\n\t\tJoined. Result = "; DestInt.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(DestInt);
- 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;
-
- 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;
-
- // 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) {
- 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 (!JoinCopy(Inst, SrcReg, DstReg))
- 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.
- 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, TryAgainList);
- }
-
- // 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 Reg, unsigned Start, unsigned End,
- 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;
-}
-
-/// 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();
- }
-}
-
-/// 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;
-}
-