| //===-- LiveInterval.cpp - Live Interval Representation -------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the LiveRange and LiveInterval classes. Given some |
| // numbering of each the machine instructions an interval [i, j) is said to be a |
| // live interval for register v if there is no instruction with number j' > j |
| // such that v is live at j' and there is no instruction with number i' < i such |
| // that v is live at i'. In this implementation intervals can have holes, |
| // i.e. an interval might look like [1,20), [50,65), [1000,1001). Each |
| // individual range is represented as an instance of LiveRange, and the whole |
| // interval is represented as an instance of LiveInterval. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/CodeGen/LiveInterval.h" |
| #include "llvm/CodeGen/LiveIntervalAnalysis.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetRegisterInfo.h" |
| #include <algorithm> |
| using namespace llvm; |
| |
| LiveInterval::iterator LiveInterval::find(SlotIndex Pos) { |
| // This algorithm is basically std::upper_bound. |
| // Unfortunately, std::upper_bound cannot be used with mixed types until we |
| // adopt C++0x. Many libraries can do it, but not all. |
| if (empty() || Pos >= endIndex()) |
| return end(); |
| iterator I = begin(); |
| size_t Len = ranges.size(); |
| do { |
| size_t Mid = Len >> 1; |
| if (Pos < I[Mid].end) |
| Len = Mid; |
| else |
| I += Mid + 1, Len -= Mid + 1; |
| } while (Len); |
| return I; |
| } |
| |
| /// killedInRange - Return true if the interval has kills in [Start,End). |
| bool LiveInterval::killedInRange(SlotIndex Start, SlotIndex End) const { |
| Ranges::const_iterator r = |
| std::lower_bound(ranges.begin(), ranges.end(), End); |
| |
| // Now r points to the first interval with start >= End, or ranges.end(). |
| if (r == ranges.begin()) |
| return false; |
| |
| --r; |
| // Now r points to the last interval with end <= End. |
| // r->end is the kill point. |
| return r->end >= Start && r->end < End; |
| } |
| |
| // overlaps - Return true if the intersection of the two live intervals is |
| // not empty. |
| // |
| // An example for overlaps(): |
| // |
| // 0: A = ... |
| // 4: B = ... |
| // 8: C = A + B ;; last use of A |
| // |
| // The live intervals should look like: |
| // |
| // A = [3, 11) |
| // B = [7, x) |
| // C = [11, y) |
| // |
| // A->overlaps(C) should return false since we want to be able to join |
| // A and C. |
| // |
| bool LiveInterval::overlapsFrom(const LiveInterval& other, |
| const_iterator StartPos) const { |
| assert(!empty() && "empty interval"); |
| const_iterator i = begin(); |
| const_iterator ie = end(); |
| const_iterator j = StartPos; |
| const_iterator je = other.end(); |
| |
| assert((StartPos->start <= i->start || StartPos == other.begin()) && |
| StartPos != other.end() && "Bogus start position hint!"); |
| |
| if (i->start < j->start) { |
| i = std::upper_bound(i, ie, j->start); |
| if (i != ranges.begin()) --i; |
| } else if (j->start < i->start) { |
| ++StartPos; |
| if (StartPos != other.end() && StartPos->start <= i->start) { |
| assert(StartPos < other.end() && i < end()); |
| j = std::upper_bound(j, je, i->start); |
| if (j != other.ranges.begin()) --j; |
| } |
| } else { |
| return true; |
| } |
| |
| if (j == je) return false; |
| |
| while (i != ie) { |
| if (i->start > j->start) { |
| std::swap(i, j); |
| std::swap(ie, je); |
| } |
| |
| if (i->end > j->start) |
| return true; |
| ++i; |
| } |
| |
| return false; |
| } |
| |
| /// overlaps - Return true if the live interval overlaps a range specified |
| /// by [Start, End). |
| bool LiveInterval::overlaps(SlotIndex Start, SlotIndex End) const { |
| assert(Start < End && "Invalid range"); |
| const_iterator I = std::lower_bound(begin(), end(), End); |
| return I != begin() && (--I)->end > Start; |
| } |
| |
| |
| /// ValNo is dead, remove it. If it is the largest value number, just nuke it |
| /// (and any other deleted values neighboring it), otherwise mark it as ~1U so |
| /// it can be nuked later. |
| void LiveInterval::markValNoForDeletion(VNInfo *ValNo) { |
| if (ValNo->id == getNumValNums()-1) { |
| do { |
| valnos.pop_back(); |
| } while (!valnos.empty() && valnos.back()->isUnused()); |
| } else { |
| ValNo->setIsUnused(true); |
| } |
| } |
| |
| /// RenumberValues - Renumber all values in order of appearance and delete the |
| /// remaining unused values. |
| void LiveInterval::RenumberValues(LiveIntervals &lis) { |
| SmallPtrSet<VNInfo*, 8> Seen; |
| valnos.clear(); |
| for (const_iterator I = begin(), E = end(); I != E; ++I) { |
| VNInfo *VNI = I->valno; |
| if (!Seen.insert(VNI)) |
| continue; |
| assert(!VNI->isUnused() && "Unused valno used by live range"); |
| VNI->id = (unsigned)valnos.size(); |
| valnos.push_back(VNI); |
| } |
| } |
| |
| /// extendIntervalEndTo - This method is used when we want to extend the range |
| /// specified by I to end at the specified endpoint. To do this, we should |
| /// merge and eliminate all ranges that this will overlap with. The iterator is |
| /// not invalidated. |
| void LiveInterval::extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd) { |
| assert(I != ranges.end() && "Not a valid interval!"); |
| VNInfo *ValNo = I->valno; |
| |
| // Search for the first interval that we can't merge with. |
| Ranges::iterator MergeTo = llvm::next(I); |
| for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo) { |
| assert(MergeTo->valno == ValNo && "Cannot merge with differing values!"); |
| } |
| |
| // If NewEnd was in the middle of an interval, make sure to get its endpoint. |
| I->end = std::max(NewEnd, prior(MergeTo)->end); |
| |
| // Erase any dead ranges. |
| ranges.erase(llvm::next(I), MergeTo); |
| |
| // If the newly formed range now touches the range after it and if they have |
| // the same value number, merge the two ranges into one range. |
| Ranges::iterator Next = llvm::next(I); |
| if (Next != ranges.end() && Next->start <= I->end && Next->valno == ValNo) { |
| I->end = Next->end; |
| ranges.erase(Next); |
| } |
| } |
| |
| |
| /// extendIntervalStartTo - This method is used when we want to extend the range |
| /// specified by I to start at the specified endpoint. To do this, we should |
| /// merge and eliminate all ranges that this will overlap with. |
| LiveInterval::Ranges::iterator |
| LiveInterval::extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStart) { |
| assert(I != ranges.end() && "Not a valid interval!"); |
| VNInfo *ValNo = I->valno; |
| |
| // Search for the first interval that we can't merge with. |
| Ranges::iterator MergeTo = I; |
| do { |
| if (MergeTo == ranges.begin()) { |
| I->start = NewStart; |
| ranges.erase(MergeTo, I); |
| return I; |
| } |
| assert(MergeTo->valno == ValNo && "Cannot merge with differing values!"); |
| --MergeTo; |
| } while (NewStart <= MergeTo->start); |
| |
| // If we start in the middle of another interval, just delete a range and |
| // extend that interval. |
| if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) { |
| MergeTo->end = I->end; |
| } else { |
| // Otherwise, extend the interval right after. |
| ++MergeTo; |
| MergeTo->start = NewStart; |
| MergeTo->end = I->end; |
| } |
| |
| ranges.erase(llvm::next(MergeTo), llvm::next(I)); |
| return MergeTo; |
| } |
| |
| LiveInterval::iterator |
| LiveInterval::addRangeFrom(LiveRange LR, iterator From) { |
| SlotIndex Start = LR.start, End = LR.end; |
| iterator it = std::upper_bound(From, ranges.end(), Start); |
| |
| // If the inserted interval starts in the middle or right at the end of |
| // another interval, just extend that interval to contain the range of LR. |
| if (it != ranges.begin()) { |
| iterator B = prior(it); |
| if (LR.valno == B->valno) { |
| if (B->start <= Start && B->end >= Start) { |
| extendIntervalEndTo(B, End); |
| return B; |
| } |
| } else { |
| // Check to make sure that we are not overlapping two live ranges with |
| // different valno's. |
| assert(B->end <= Start && |
| "Cannot overlap two LiveRanges with differing ValID's" |
| " (did you def the same reg twice in a MachineInstr?)"); |
| } |
| } |
| |
| // Otherwise, if this range ends in the middle of, or right next to, another |
| // interval, merge it into that interval. |
| if (it != ranges.end()) { |
| if (LR.valno == it->valno) { |
| if (it->start <= End) { |
| it = extendIntervalStartTo(it, Start); |
| |
| // If LR is a complete superset of an interval, we may need to grow its |
| // endpoint as well. |
| if (End > it->end) |
| extendIntervalEndTo(it, End); |
| return it; |
| } |
| } else { |
| // Check to make sure that we are not overlapping two live ranges with |
| // different valno's. |
| assert(it->start >= End && |
| "Cannot overlap two LiveRanges with differing ValID's"); |
| } |
| } |
| |
| // Otherwise, this is just a new range that doesn't interact with anything. |
| // Insert it. |
| return ranges.insert(it, LR); |
| } |
| |
| /// extendInBlock - If this interval is live before Kill in the basic |
| /// block that starts at StartIdx, extend it to be live up to Kill and return |
| /// the value. If there is no live range before Kill, return NULL. |
| VNInfo *LiveInterval::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) { |
| if (empty()) |
| return 0; |
| iterator I = std::upper_bound(begin(), end(), Kill.getPrevSlot()); |
| if (I == begin()) |
| return 0; |
| --I; |
| if (I->end <= StartIdx) |
| return 0; |
| if (I->end < Kill) |
| extendIntervalEndTo(I, Kill); |
| return I->valno; |
| } |
| |
| /// removeRange - Remove the specified range from this interval. Note that |
| /// the range must be in a single LiveRange in its entirety. |
| void LiveInterval::removeRange(SlotIndex Start, SlotIndex End, |
| bool RemoveDeadValNo) { |
| // Find the LiveRange containing this span. |
| Ranges::iterator I = find(Start); |
| assert(I != ranges.end() && "Range is not in interval!"); |
| assert(I->containsRange(Start, End) && "Range is not entirely in interval!"); |
| |
| // If the span we are removing is at the start of the LiveRange, adjust it. |
| VNInfo *ValNo = I->valno; |
| if (I->start == Start) { |
| if (I->end == End) { |
| if (RemoveDeadValNo) { |
| // Check if val# is dead. |
| bool isDead = true; |
| for (const_iterator II = begin(), EE = end(); II != EE; ++II) |
| if (II != I && II->valno == ValNo) { |
| isDead = false; |
| break; |
| } |
| if (isDead) { |
| // Now that ValNo is dead, remove it. |
| markValNoForDeletion(ValNo); |
| } |
| } |
| |
| ranges.erase(I); // Removed the whole LiveRange. |
| } else |
| I->start = End; |
| return; |
| } |
| |
| // Otherwise if the span we are removing is at the end of the LiveRange, |
| // adjust the other way. |
| if (I->end == End) { |
| I->end = Start; |
| return; |
| } |
| |
| // Otherwise, we are splitting the LiveRange into two pieces. |
| SlotIndex OldEnd = I->end; |
| I->end = Start; // Trim the old interval. |
| |
| // Insert the new one. |
| ranges.insert(llvm::next(I), LiveRange(End, OldEnd, ValNo)); |
| } |
| |
| /// removeValNo - Remove all the ranges defined by the specified value#. |
| /// Also remove the value# from value# list. |
| void LiveInterval::removeValNo(VNInfo *ValNo) { |
| if (empty()) return; |
| Ranges::iterator I = ranges.end(); |
| Ranges::iterator E = ranges.begin(); |
| do { |
| --I; |
| if (I->valno == ValNo) |
| ranges.erase(I); |
| } while (I != E); |
| // Now that ValNo is dead, remove it. |
| markValNoForDeletion(ValNo); |
| } |
| |
| /// findDefinedVNInfo - Find the VNInfo defined by the specified |
| /// index (register interval). |
| VNInfo *LiveInterval::findDefinedVNInfoForRegInt(SlotIndex Idx) const { |
| for (LiveInterval::const_vni_iterator i = vni_begin(), e = vni_end(); |
| i != e; ++i) { |
| if ((*i)->def == Idx) |
| return *i; |
| } |
| |
| return 0; |
| } |
| |
| /// join - Join two live intervals (this, and other) together. This applies |
| /// mappings to the value numbers in the LHS/RHS intervals as specified. If |
| /// the intervals are not joinable, this aborts. |
| void LiveInterval::join(LiveInterval &Other, |
| const int *LHSValNoAssignments, |
| const int *RHSValNoAssignments, |
| SmallVector<VNInfo*, 16> &NewVNInfo, |
| MachineRegisterInfo *MRI) { |
| // Determine if any of our live range values are mapped. This is uncommon, so |
| // we want to avoid the interval scan if not. |
| bool MustMapCurValNos = false; |
| unsigned NumVals = getNumValNums(); |
| unsigned NumNewVals = NewVNInfo.size(); |
| for (unsigned i = 0; i != NumVals; ++i) { |
| unsigned LHSValID = LHSValNoAssignments[i]; |
| if (i != LHSValID || |
| (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i))) |
| MustMapCurValNos = true; |
| } |
| |
| // If we have to apply a mapping to our base interval assignment, rewrite it |
| // now. |
| if (MustMapCurValNos) { |
| // Map the first live range. |
| iterator OutIt = begin(); |
| OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]]; |
| ++OutIt; |
| for (iterator I = OutIt, E = end(); I != E; ++I) { |
| OutIt->valno = NewVNInfo[LHSValNoAssignments[I->valno->id]]; |
| |
| // If this live range has the same value # as its immediate predecessor, |
| // and if they are neighbors, remove one LiveRange. This happens when we |
| // have [0,3:0)[4,7:1) and map 0/1 onto the same value #. |
| if (OutIt->valno == (OutIt-1)->valno && (OutIt-1)->end == OutIt->start) { |
| (OutIt-1)->end = OutIt->end; |
| } else { |
| if (I != OutIt) { |
| OutIt->start = I->start; |
| OutIt->end = I->end; |
| } |
| |
| // Didn't merge, on to the next one. |
| ++OutIt; |
| } |
| } |
| |
| // If we merge some live ranges, chop off the end. |
| ranges.erase(OutIt, end()); |
| } |
| |
| // Remember assignements because val# ids are changing. |
| SmallVector<unsigned, 16> OtherAssignments; |
| for (iterator I = Other.begin(), E = Other.end(); I != E; ++I) |
| OtherAssignments.push_back(RHSValNoAssignments[I->valno->id]); |
| |
| // Update val# info. Renumber them and make sure they all belong to this |
| // LiveInterval now. Also remove dead val#'s. |
| unsigned NumValNos = 0; |
| for (unsigned i = 0; i < NumNewVals; ++i) { |
| VNInfo *VNI = NewVNInfo[i]; |
| if (VNI) { |
| if (NumValNos >= NumVals) |
| valnos.push_back(VNI); |
| else |
| valnos[NumValNos] = VNI; |
| VNI->id = NumValNos++; // Renumber val#. |
| } |
| } |
| if (NumNewVals < NumVals) |
| valnos.resize(NumNewVals); // shrinkify |
| |
| // Okay, now insert the RHS live ranges into the LHS. |
| iterator InsertPos = begin(); |
| unsigned RangeNo = 0; |
| for (iterator I = Other.begin(), E = Other.end(); I != E; ++I, ++RangeNo) { |
| // Map the valno in the other live range to the current live range. |
| I->valno = NewVNInfo[OtherAssignments[RangeNo]]; |
| assert(I->valno && "Adding a dead range?"); |
| InsertPos = addRangeFrom(*I, InsertPos); |
| } |
| |
| ComputeJoinedWeight(Other); |
| } |
| |
| /// MergeRangesInAsValue - Merge all of the intervals in RHS into this live |
| /// interval as the specified value number. The LiveRanges in RHS are |
| /// allowed to overlap with LiveRanges in the current interval, but only if |
| /// the overlapping LiveRanges have the specified value number. |
| void LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS, |
| VNInfo *LHSValNo) { |
| // TODO: Make this more efficient. |
| iterator InsertPos = begin(); |
| for (const_iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) { |
| // Map the valno in the other live range to the current live range. |
| LiveRange Tmp = *I; |
| Tmp.valno = LHSValNo; |
| InsertPos = addRangeFrom(Tmp, InsertPos); |
| } |
| } |
| |
| |
| /// MergeValueInAsValue - Merge all of the live ranges of a specific val# |
| /// in RHS into this live interval as the specified value number. |
| /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the |
| /// current interval, it will replace the value numbers of the overlaped |
| /// live ranges with the specified value number. |
| void LiveInterval::MergeValueInAsValue( |
| const LiveInterval &RHS, |
| const VNInfo *RHSValNo, VNInfo *LHSValNo) { |
| // TODO: Make this more efficient. |
| iterator InsertPos = begin(); |
| for (const_iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) { |
| if (I->valno != RHSValNo) |
| continue; |
| // Map the valno in the other live range to the current live range. |
| LiveRange Tmp = *I; |
| Tmp.valno = LHSValNo; |
| InsertPos = addRangeFrom(Tmp, InsertPos); |
| } |
| } |
| |
| |
| /// MergeValueNumberInto - This method is called when two value nubmers |
| /// are found to be equivalent. This eliminates V1, replacing all |
| /// LiveRanges with the V1 value number with the V2 value number. This can |
| /// cause merging of V1/V2 values numbers and compaction of the value space. |
| VNInfo* LiveInterval::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) { |
| assert(V1 != V2 && "Identical value#'s are always equivalent!"); |
| |
| // This code actually merges the (numerically) larger value number into the |
| // smaller value number, which is likely to allow us to compactify the value |
| // space. The only thing we have to be careful of is to preserve the |
| // instruction that defines the result value. |
| |
| // Make sure V2 is smaller than V1. |
| if (V1->id < V2->id) { |
| V1->copyFrom(*V2); |
| std::swap(V1, V2); |
| } |
| |
| // Merge V1 live ranges into V2. |
| for (iterator I = begin(); I != end(); ) { |
| iterator LR = I++; |
| if (LR->valno != V1) continue; // Not a V1 LiveRange. |
| |
| // Okay, we found a V1 live range. If it had a previous, touching, V2 live |
| // range, extend it. |
| if (LR != begin()) { |
| iterator Prev = LR-1; |
| if (Prev->valno == V2 && Prev->end == LR->start) { |
| Prev->end = LR->end; |
| |
| // Erase this live-range. |
| ranges.erase(LR); |
| I = Prev+1; |
| LR = Prev; |
| } |
| } |
| |
| // Okay, now we have a V1 or V2 live range that is maximally merged forward. |
| // Ensure that it is a V2 live-range. |
| LR->valno = V2; |
| |
| // If we can merge it into later V2 live ranges, do so now. We ignore any |
| // following V1 live ranges, as they will be merged in subsequent iterations |
| // of the loop. |
| if (I != end()) { |
| if (I->start == LR->end && I->valno == V2) { |
| LR->end = I->end; |
| ranges.erase(I); |
| I = LR+1; |
| } |
| } |
| } |
| |
| // Merge the relevant flags. |
| V2->mergeFlags(V1); |
| |
| // Now that V1 is dead, remove it. |
| markValNoForDeletion(V1); |
| |
| return V2; |
| } |
| |
| void LiveInterval::Copy(const LiveInterval &RHS, |
| MachineRegisterInfo *MRI, |
| VNInfo::Allocator &VNInfoAllocator) { |
| ranges.clear(); |
| valnos.clear(); |
| std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(RHS.reg); |
| MRI->setRegAllocationHint(reg, Hint.first, Hint.second); |
| |
| weight = RHS.weight; |
| for (unsigned i = 0, e = RHS.getNumValNums(); i != e; ++i) { |
| const VNInfo *VNI = RHS.getValNumInfo(i); |
| createValueCopy(VNI, VNInfoAllocator); |
| } |
| for (unsigned i = 0, e = RHS.ranges.size(); i != e; ++i) { |
| const LiveRange &LR = RHS.ranges[i]; |
| addRange(LiveRange(LR.start, LR.end, getValNumInfo(LR.valno->id))); |
| } |
| } |
| |
| unsigned LiveInterval::getSize() const { |
| unsigned Sum = 0; |
| for (const_iterator I = begin(), E = end(); I != E; ++I) |
| Sum += I->start.distance(I->end); |
| return Sum; |
| } |
| |
| /// ComputeJoinedWeight - Set the weight of a live interval Joined |
| /// after Other has been merged into it. |
| void LiveInterval::ComputeJoinedWeight(const LiveInterval &Other) { |
| // If either of these intervals was spilled, the weight is the |
| // weight of the non-spilled interval. This can only happen with |
| // iterative coalescers. |
| |
| if (Other.weight != HUGE_VALF) { |
| weight += Other.weight; |
| } |
| else if (weight == HUGE_VALF && |
| !TargetRegisterInfo::isPhysicalRegister(reg)) { |
| // Remove this assert if you have an iterative coalescer |
| assert(0 && "Joining to spilled interval"); |
| weight = Other.weight; |
| } |
| else { |
| // Otherwise the weight stays the same |
| // Remove this assert if you have an iterative coalescer |
| assert(0 && "Joining from spilled interval"); |
| } |
| } |
| |
| raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange &LR) { |
| return os << '[' << LR.start << ',' << LR.end << ':' << LR.valno->id << ")"; |
| } |
| |
| void LiveRange::dump() const { |
| dbgs() << *this << "\n"; |
| } |
| |
| void LiveInterval::print(raw_ostream &OS, const TargetRegisterInfo *TRI) const { |
| OS << PrintReg(reg, TRI); |
| if (weight != 0) |
| OS << ',' << weight; |
| |
| if (empty()) |
| OS << " EMPTY"; |
| else { |
| OS << " = "; |
| for (LiveInterval::Ranges::const_iterator I = ranges.begin(), |
| E = ranges.end(); I != E; ++I) { |
| OS << *I; |
| assert(I->valno == getValNumInfo(I->valno->id) && "Bad VNInfo"); |
| } |
| } |
| |
| // Print value number info. |
| if (getNumValNums()) { |
| OS << " "; |
| unsigned vnum = 0; |
| for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e; |
| ++i, ++vnum) { |
| const VNInfo *vni = *i; |
| if (vnum) OS << " "; |
| OS << vnum << "@"; |
| if (vni->isUnused()) { |
| OS << "x"; |
| } else { |
| OS << vni->def; |
| if (vni->isPHIDef()) |
| OS << "-phidef"; |
| if (vni->hasPHIKill()) |
| OS << "-phikill"; |
| if (vni->hasRedefByEC()) |
| OS << "-ec"; |
| } |
| } |
| } |
| } |
| |
| void LiveInterval::dump() const { |
| dbgs() << *this << "\n"; |
| } |
| |
| |
| void LiveRange::print(raw_ostream &os) const { |
| os << *this; |
| } |
| |
| unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) { |
| // Create initial equivalence classes. |
| EqClass.clear(); |
| EqClass.grow(LI->getNumValNums()); |
| |
| const VNInfo *used = 0, *unused = 0; |
| |
| // Determine connections. |
| for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end(); |
| I != E; ++I) { |
| const VNInfo *VNI = *I; |
| // Group all unused values into one class. |
| if (VNI->isUnused()) { |
| if (unused) |
| EqClass.join(unused->id, VNI->id); |
| unused = VNI; |
| continue; |
| } |
| used = VNI; |
| if (VNI->isPHIDef()) { |
| const MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def); |
| assert(MBB && "Phi-def has no defining MBB"); |
| // Connect to values live out of predecessors. |
| for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), |
| PE = MBB->pred_end(); PI != PE; ++PI) |
| if (const VNInfo *PVNI = LI->getVNInfoBefore(LIS.getMBBEndIdx(*PI))) |
| EqClass.join(VNI->id, PVNI->id); |
| } else { |
| // Normal value defined by an instruction. Check for two-addr redef. |
| // FIXME: This could be coincidental. Should we really check for a tied |
| // operand constraint? |
| // Note that VNI->def may be a use slot for an early clobber def. |
| if (const VNInfo *UVNI = LI->getVNInfoBefore(VNI->def)) |
| EqClass.join(VNI->id, UVNI->id); |
| } |
| } |
| |
| // Lump all the unused values in with the last used value. |
| if (used && unused) |
| EqClass.join(used->id, unused->id); |
| |
| EqClass.compress(); |
| return EqClass.getNumClasses(); |
| } |
| |
| void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[], |
| MachineRegisterInfo &MRI) { |
| assert(LIV[0] && "LIV[0] must be set"); |
| LiveInterval &LI = *LIV[0]; |
| |
| // Rewrite instructions. |
| for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg), |
| RE = MRI.reg_end(); RI != RE;) { |
| MachineOperand &MO = RI.getOperand(); |
| MachineInstr *MI = MO.getParent(); |
| ++RI; |
| if (MO.isUse() && MO.isUndef()) |
| continue; |
| // DBG_VALUE instructions should have been eliminated earlier. |
| SlotIndex Idx = LIS.getInstructionIndex(MI); |
| Idx = Idx.getRegSlot(MO.isUse()); |
| const VNInfo *VNI = LI.getVNInfoAt(Idx); |
| assert(VNI && "Interval not live at use."); |
| MO.setReg(LIV[getEqClass(VNI)]->reg); |
| } |
| |
| // Move runs to new intervals. |
| LiveInterval::iterator J = LI.begin(), E = LI.end(); |
| while (J != E && EqClass[J->valno->id] == 0) |
| ++J; |
| for (LiveInterval::iterator I = J; I != E; ++I) { |
| if (unsigned eq = EqClass[I->valno->id]) { |
| assert((LIV[eq]->empty() || LIV[eq]->expiredAt(I->start)) && |
| "New intervals should be empty"); |
| LIV[eq]->ranges.push_back(*I); |
| } else |
| *J++ = *I; |
| } |
| LI.ranges.erase(J, E); |
| |
| // Transfer VNInfos to their new owners and renumber them. |
| unsigned j = 0, e = LI.getNumValNums(); |
| while (j != e && EqClass[j] == 0) |
| ++j; |
| for (unsigned i = j; i != e; ++i) { |
| VNInfo *VNI = LI.getValNumInfo(i); |
| if (unsigned eq = EqClass[i]) { |
| VNI->id = LIV[eq]->getNumValNums(); |
| LIV[eq]->valnos.push_back(VNI); |
| } else { |
| VNI->id = j; |
| LI.valnos[j++] = VNI; |
| } |
| } |
| LI.valnos.resize(j); |
| } |