1 //===-- LiveInterval.cpp - Live Interval Representation -------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LiveRange and LiveInterval classes. Given some
11 // numbering of each the machine instructions an interval [i, j) is said to be a
12 // live range for register v if there is no instruction with number j' >= j
13 // such that v is live at j' and there is no instruction with number i' < i such
14 // that v is live at i'. In this implementation ranges can have holes,
15 // i.e. a range might look like [1,20), [50,65), [1000,1001). Each
16 // individual segment is represented as an instance of LiveRange::Segment,
17 // and the whole range is represented as an instance of LiveRange.
19 //===----------------------------------------------------------------------===//
21 #include "llvm/CodeGen/LiveInterval.h"
23 #include "LiveRangeUtils.h"
24 #include "RegisterCoalescer.h"
25 #include "llvm/ADT/STLExtras.h"
26 #include "llvm/ADT/SmallSet.h"
27 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
28 #include "llvm/CodeGen/MachineRegisterInfo.h"
29 #include "llvm/Support/Debug.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/Target/TargetRegisterInfo.h"
36 //===----------------------------------------------------------------------===//
37 // Implementation of various methods necessary for calculation of live ranges.
38 // The implementation of the methods abstracts from the concrete type of the
39 // segment collection.
41 // Implementation of the class follows the Template design pattern. The base
42 // class contains generic algorithms that call collection-specific methods,
43 // which are provided in concrete subclasses. In order to avoid virtual calls
44 // these methods are provided by means of C++ template instantiation.
45 // The base class calls the methods of the subclass through method impl(),
46 // which casts 'this' pointer to the type of the subclass.
48 //===----------------------------------------------------------------------===//
50 template <typename ImplT, typename IteratorT, typename CollectionT>
51 class CalcLiveRangeUtilBase {
56 CalcLiveRangeUtilBase(LiveRange *LR) : LR(LR) {}
59 typedef LiveRange::Segment Segment;
60 typedef IteratorT iterator;
62 VNInfo *createDeadDef(SlotIndex Def, VNInfo::Allocator &VNInfoAllocator) {
63 assert(!Def.isDead() && "Cannot define a value at the dead slot");
65 iterator I = impl().find(Def);
66 if (I == segments().end()) {
67 VNInfo *VNI = LR->getNextValue(Def, VNInfoAllocator);
68 impl().insertAtEnd(Segment(Def, Def.getDeadSlot(), VNI));
72 Segment *S = segmentAt(I);
73 if (SlotIndex::isSameInstr(Def, S->start)) {
74 assert(S->valno->def == S->start && "Inconsistent existing value def");
76 // It is possible to have both normal and early-clobber defs of the same
77 // register on an instruction. It doesn't make a lot of sense, but it is
78 // possible to specify in inline assembly.
80 // Just convert everything to early-clobber.
81 Def = std::min(Def, S->start);
83 S->start = S->valno->def = Def;
86 assert(SlotIndex::isEarlierInstr(Def, S->start) && "Already live at def");
87 VNInfo *VNI = LR->getNextValue(Def, VNInfoAllocator);
88 segments().insert(I, Segment(Def, Def.getDeadSlot(), VNI));
92 VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex Use) {
93 if (segments().empty())
96 impl().findInsertPos(Segment(Use.getPrevSlot(), Use, nullptr));
97 if (I == segments().begin())
100 if (I->end <= StartIdx)
103 extendSegmentEndTo(I, Use);
107 /// This method is used when we want to extend the segment specified
108 /// by I to end at the specified endpoint. To do this, we should
109 /// merge and eliminate all segments that this will overlap
110 /// with. The iterator is not invalidated.
111 void extendSegmentEndTo(iterator I, SlotIndex NewEnd) {
112 assert(I != segments().end() && "Not a valid segment!");
113 Segment *S = segmentAt(I);
114 VNInfo *ValNo = I->valno;
116 // Search for the first segment that we can't merge with.
117 iterator MergeTo = std::next(I);
118 for (; MergeTo != segments().end() && NewEnd >= MergeTo->end; ++MergeTo)
119 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
121 // If NewEnd was in the middle of a segment, make sure to get its endpoint.
122 S->end = std::max(NewEnd, std::prev(MergeTo)->end);
124 // If the newly formed segment now touches the segment after it and if they
125 // have the same value number, merge the two segments into one segment.
126 if (MergeTo != segments().end() && MergeTo->start <= I->end &&
127 MergeTo->valno == ValNo) {
128 S->end = MergeTo->end;
132 // Erase any dead segments.
133 segments().erase(std::next(I), MergeTo);
136 /// This method is used when we want to extend the segment specified
137 /// by I to start at the specified endpoint. To do this, we should
138 /// merge and eliminate all segments that this will overlap with.
139 iterator extendSegmentStartTo(iterator I, SlotIndex NewStart) {
140 assert(I != segments().end() && "Not a valid segment!");
141 Segment *S = segmentAt(I);
142 VNInfo *ValNo = I->valno;
144 // Search for the first segment that we can't merge with.
145 iterator MergeTo = I;
147 if (MergeTo == segments().begin()) {
149 segments().erase(MergeTo, I);
152 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
154 } while (NewStart <= MergeTo->start);
156 // If we start in the middle of another segment, just delete a range and
157 // extend that segment.
158 if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) {
159 segmentAt(MergeTo)->end = S->end;
161 // Otherwise, extend the segment right after.
163 Segment *MergeToSeg = segmentAt(MergeTo);
164 MergeToSeg->start = NewStart;
165 MergeToSeg->end = S->end;
168 segments().erase(std::next(MergeTo), std::next(I));
172 iterator addSegment(Segment S) {
173 SlotIndex Start = S.start, End = S.end;
174 iterator I = impl().findInsertPos(S);
176 // If the inserted segment starts in the middle or right at the end of
177 // another segment, just extend that segment to contain the segment of S.
178 if (I != segments().begin()) {
179 iterator B = std::prev(I);
180 if (S.valno == B->valno) {
181 if (B->start <= Start && B->end >= Start) {
182 extendSegmentEndTo(B, End);
186 // Check to make sure that we are not overlapping two live segments with
187 // different valno's.
188 assert(B->end <= Start &&
189 "Cannot overlap two segments with differing ValID's"
190 " (did you def the same reg twice in a MachineInstr?)");
194 // Otherwise, if this segment ends in the middle of, or right next
195 // to, another segment, merge it into that segment.
196 if (I != segments().end()) {
197 if (S.valno == I->valno) {
198 if (I->start <= End) {
199 I = extendSegmentStartTo(I, Start);
201 // If S is a complete superset of a segment, we may need to grow its
204 extendSegmentEndTo(I, End);
208 // Check to make sure that we are not overlapping two live segments with
209 // different valno's.
210 assert(I->start >= End &&
211 "Cannot overlap two segments with differing ValID's");
215 // Otherwise, this is just a new segment that doesn't interact with
218 return segments().insert(I, S);
222 ImplT &impl() { return *static_cast<ImplT *>(this); }
224 CollectionT &segments() { return impl().segmentsColl(); }
226 Segment *segmentAt(iterator I) { return const_cast<Segment *>(&(*I)); }
229 //===----------------------------------------------------------------------===//
230 // Instantiation of the methods for calculation of live ranges
231 // based on a segment vector.
232 //===----------------------------------------------------------------------===//
234 class CalcLiveRangeUtilVector;
235 typedef CalcLiveRangeUtilBase<CalcLiveRangeUtilVector, LiveRange::iterator,
236 LiveRange::Segments> CalcLiveRangeUtilVectorBase;
238 class CalcLiveRangeUtilVector : public CalcLiveRangeUtilVectorBase {
240 CalcLiveRangeUtilVector(LiveRange *LR) : CalcLiveRangeUtilVectorBase(LR) {}
243 friend CalcLiveRangeUtilVectorBase;
245 LiveRange::Segments &segmentsColl() { return LR->segments; }
247 void insertAtEnd(const Segment &S) { LR->segments.push_back(S); }
249 iterator find(SlotIndex Pos) { return LR->find(Pos); }
251 iterator findInsertPos(Segment S) {
252 return std::upper_bound(LR->begin(), LR->end(), S.start);
256 //===----------------------------------------------------------------------===//
257 // Instantiation of the methods for calculation of live ranges
258 // based on a segment set.
259 //===----------------------------------------------------------------------===//
261 class CalcLiveRangeUtilSet;
262 typedef CalcLiveRangeUtilBase<CalcLiveRangeUtilSet,
263 LiveRange::SegmentSet::iterator,
264 LiveRange::SegmentSet> CalcLiveRangeUtilSetBase;
266 class CalcLiveRangeUtilSet : public CalcLiveRangeUtilSetBase {
268 CalcLiveRangeUtilSet(LiveRange *LR) : CalcLiveRangeUtilSetBase(LR) {}
271 friend CalcLiveRangeUtilSetBase;
273 LiveRange::SegmentSet &segmentsColl() { return *LR->segmentSet; }
275 void insertAtEnd(const Segment &S) {
276 LR->segmentSet->insert(LR->segmentSet->end(), S);
279 iterator find(SlotIndex Pos) {
281 LR->segmentSet->upper_bound(Segment(Pos, Pos.getNextSlot(), nullptr));
282 if (I == LR->segmentSet->begin())
284 iterator PrevI = std::prev(I);
285 if (Pos < (*PrevI).end)
290 iterator findInsertPos(Segment S) {
291 iterator I = LR->segmentSet->upper_bound(S);
292 if (I != LR->segmentSet->end() && !(S.start < *I))
299 //===----------------------------------------------------------------------===//
301 //===----------------------------------------------------------------------===//
303 LiveRange::iterator LiveRange::find(SlotIndex Pos) {
304 // This algorithm is basically std::upper_bound.
305 // Unfortunately, std::upper_bound cannot be used with mixed types until we
306 // adopt C++0x. Many libraries can do it, but not all.
307 if (empty() || Pos >= endIndex())
309 iterator I = begin();
312 size_t Mid = Len >> 1;
313 if (Pos < I[Mid].end) {
323 VNInfo *LiveRange::createDeadDef(SlotIndex Def,
324 VNInfo::Allocator &VNInfoAllocator) {
325 // Use the segment set, if it is available.
326 if (segmentSet != nullptr)
327 return CalcLiveRangeUtilSet(this).createDeadDef(Def, VNInfoAllocator);
328 // Otherwise use the segment vector.
329 return CalcLiveRangeUtilVector(this).createDeadDef(Def, VNInfoAllocator);
332 // overlaps - Return true if the intersection of the two live ranges is
335 // An example for overlaps():
339 // 8: C = A + B ;; last use of A
341 // The live ranges should look like:
347 // A->overlaps(C) should return false since we want to be able to join
350 bool LiveRange::overlapsFrom(const LiveRange& other,
351 const_iterator StartPos) const {
352 assert(!empty() && "empty range");
353 const_iterator i = begin();
354 const_iterator ie = end();
355 const_iterator j = StartPos;
356 const_iterator je = other.end();
358 assert((StartPos->start <= i->start || StartPos == other.begin()) &&
359 StartPos != other.end() && "Bogus start position hint!");
361 if (i->start < j->start) {
362 i = std::upper_bound(i, ie, j->start);
363 if (i != begin()) --i;
364 } else if (j->start < i->start) {
366 if (StartPos != other.end() && StartPos->start <= i->start) {
367 assert(StartPos < other.end() && i < end());
368 j = std::upper_bound(j, je, i->start);
369 if (j != other.begin()) --j;
375 if (j == je) return false;
378 if (i->start > j->start) {
383 if (i->end > j->start)
391 bool LiveRange::overlaps(const LiveRange &Other, const CoalescerPair &CP,
392 const SlotIndexes &Indexes) const {
393 assert(!empty() && "empty range");
397 // Use binary searches to find initial positions.
398 const_iterator I = find(Other.beginIndex());
399 const_iterator IE = end();
402 const_iterator J = Other.find(I->start);
403 const_iterator JE = Other.end();
408 // J has just been advanced to satisfy:
409 assert(J->end >= I->start);
410 // Check for an overlap.
411 if (J->start < I->end) {
412 // I and J are overlapping. Find the later start.
413 SlotIndex Def = std::max(I->start, J->start);
414 // Allow the overlap if Def is a coalescable copy.
416 !CP.isCoalescable(Indexes.getInstructionFromIndex(Def)))
419 // Advance the iterator that ends first to check for more overlaps.
420 if (J->end > I->end) {
424 // Advance J until J->end >= I->start.
428 while (J->end < I->start);
432 /// overlaps - Return true if the live range overlaps an interval specified
434 bool LiveRange::overlaps(SlotIndex Start, SlotIndex End) const {
435 assert(Start < End && "Invalid range");
436 const_iterator I = std::lower_bound(begin(), end(), End);
437 return I != begin() && (--I)->end > Start;
440 bool LiveRange::covers(const LiveRange &Other) const {
442 return Other.empty();
444 const_iterator I = begin();
445 for (const Segment &O : Other.segments) {
446 I = advanceTo(I, O.start);
447 if (I == end() || I->start > O.start)
450 // Check adjacent live segments and see if we can get behind O.end.
451 while (I->end < O.end) {
452 const_iterator Last = I;
453 // Get next segment and abort if it was not adjacent.
455 if (I == end() || Last->end != I->start)
462 /// ValNo is dead, remove it. If it is the largest value number, just nuke it
463 /// (and any other deleted values neighboring it), otherwise mark it as ~1U so
464 /// it can be nuked later.
465 void LiveRange::markValNoForDeletion(VNInfo *ValNo) {
466 if (ValNo->id == getNumValNums()-1) {
469 } while (!valnos.empty() && valnos.back()->isUnused());
475 /// RenumberValues - Renumber all values in order of appearance and delete the
476 /// remaining unused values.
477 void LiveRange::RenumberValues() {
478 SmallPtrSet<VNInfo*, 8> Seen;
480 for (const Segment &S : segments) {
481 VNInfo *VNI = S.valno;
482 if (!Seen.insert(VNI).second)
484 assert(!VNI->isUnused() && "Unused valno used by live segment");
485 VNI->id = (unsigned)valnos.size();
486 valnos.push_back(VNI);
490 void LiveRange::addSegmentToSet(Segment S) {
491 CalcLiveRangeUtilSet(this).addSegment(S);
494 LiveRange::iterator LiveRange::addSegment(Segment S) {
495 // Use the segment set, if it is available.
496 if (segmentSet != nullptr) {
500 // Otherwise use the segment vector.
501 return CalcLiveRangeUtilVector(this).addSegment(S);
504 void LiveRange::append(const Segment S) {
505 // Check that the segment belongs to the back of the list.
506 assert(segments.empty() || segments.back().end <= S.start);
507 segments.push_back(S);
510 /// extendInBlock - If this range is live before Kill in the basic
511 /// block that starts at StartIdx, extend it to be live up to Kill and return
512 /// the value. If there is no live range before Kill, return NULL.
513 VNInfo *LiveRange::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) {
514 // Use the segment set, if it is available.
515 if (segmentSet != nullptr)
516 return CalcLiveRangeUtilSet(this).extendInBlock(StartIdx, Kill);
517 // Otherwise use the segment vector.
518 return CalcLiveRangeUtilVector(this).extendInBlock(StartIdx, Kill);
521 /// Remove the specified segment from this range. Note that the segment must
522 /// be in a single Segment in its entirety.
523 void LiveRange::removeSegment(SlotIndex Start, SlotIndex End,
524 bool RemoveDeadValNo) {
525 // Find the Segment containing this span.
526 iterator I = find(Start);
527 assert(I != end() && "Segment is not in range!");
528 assert(I->containsInterval(Start, End)
529 && "Segment is not entirely in range!");
531 // If the span we are removing is at the start of the Segment, adjust it.
532 VNInfo *ValNo = I->valno;
533 if (I->start == Start) {
535 if (RemoveDeadValNo) {
536 // Check if val# is dead.
538 for (const_iterator II = begin(), EE = end(); II != EE; ++II)
539 if (II != I && II->valno == ValNo) {
544 // Now that ValNo is dead, remove it.
545 markValNoForDeletion(ValNo);
549 segments.erase(I); // Removed the whole Segment.
555 // Otherwise if the span we are removing is at the end of the Segment,
556 // adjust the other way.
562 // Otherwise, we are splitting the Segment into two pieces.
563 SlotIndex OldEnd = I->end;
564 I->end = Start; // Trim the old segment.
566 // Insert the new one.
567 segments.insert(std::next(I), Segment(End, OldEnd, ValNo));
570 /// removeValNo - Remove all the segments defined by the specified value#.
571 /// Also remove the value# from value# list.
572 void LiveRange::removeValNo(VNInfo *ValNo) {
574 segments.erase(std::remove_if(begin(), end(), [ValNo](const Segment &S) {
575 return S.valno == ValNo;
577 // Now that ValNo is dead, remove it.
578 markValNoForDeletion(ValNo);
581 void LiveRange::join(LiveRange &Other,
582 const int *LHSValNoAssignments,
583 const int *RHSValNoAssignments,
584 SmallVectorImpl<VNInfo *> &NewVNInfo) {
587 // Determine if any of our values are mapped. This is uncommon, so we want
588 // to avoid the range scan if not.
589 bool MustMapCurValNos = false;
590 unsigned NumVals = getNumValNums();
591 unsigned NumNewVals = NewVNInfo.size();
592 for (unsigned i = 0; i != NumVals; ++i) {
593 unsigned LHSValID = LHSValNoAssignments[i];
595 (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i))) {
596 MustMapCurValNos = true;
601 // If we have to apply a mapping to our base range assignment, rewrite it now.
602 if (MustMapCurValNos && !empty()) {
603 // Map the first live range.
605 iterator OutIt = begin();
606 OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]];
607 for (iterator I = std::next(OutIt), E = end(); I != E; ++I) {
608 VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]];
609 assert(nextValNo && "Huh?");
611 // If this live range has the same value # as its immediate predecessor,
612 // and if they are neighbors, remove one Segment. This happens when we
613 // have [0,4:0)[4,7:1) and map 0/1 onto the same value #.
614 if (OutIt->valno == nextValNo && OutIt->end == I->start) {
617 // Didn't merge. Move OutIt to the next segment,
619 OutIt->valno = nextValNo;
621 OutIt->start = I->start;
626 // If we merge some segments, chop off the end.
628 segments.erase(OutIt, end());
631 // Rewrite Other values before changing the VNInfo ids.
632 // This can leave Other in an invalid state because we're not coalescing
633 // touching segments that now have identical values. That's OK since Other is
634 // not supposed to be valid after calling join();
635 for (Segment &S : Other.segments)
636 S.valno = NewVNInfo[RHSValNoAssignments[S.valno->id]];
638 // Update val# info. Renumber them and make sure they all belong to this
639 // LiveRange now. Also remove dead val#'s.
640 unsigned NumValNos = 0;
641 for (unsigned i = 0; i < NumNewVals; ++i) {
642 VNInfo *VNI = NewVNInfo[i];
644 if (NumValNos >= NumVals)
645 valnos.push_back(VNI);
647 valnos[NumValNos] = VNI;
648 VNI->id = NumValNos++; // Renumber val#.
651 if (NumNewVals < NumVals)
652 valnos.resize(NumNewVals); // shrinkify
654 // Okay, now insert the RHS live segments into the LHS.
655 LiveRangeUpdater Updater(this);
656 for (Segment &S : Other.segments)
660 /// Merge all of the segments in RHS into this live range as the specified
661 /// value number. The segments in RHS are allowed to overlap with segments in
662 /// the current range, but only if the overlapping segments have the
663 /// specified value number.
664 void LiveRange::MergeSegmentsInAsValue(const LiveRange &RHS,
666 LiveRangeUpdater Updater(this);
667 for (const Segment &S : RHS.segments)
668 Updater.add(S.start, S.end, LHSValNo);
671 /// MergeValueInAsValue - Merge all of the live segments of a specific val#
672 /// in RHS into this live range as the specified value number.
673 /// The segments in RHS are allowed to overlap with segments in the
674 /// current range, it will replace the value numbers of the overlaped
675 /// segments with the specified value number.
676 void LiveRange::MergeValueInAsValue(const LiveRange &RHS,
677 const VNInfo *RHSValNo,
679 LiveRangeUpdater Updater(this);
680 for (const Segment &S : RHS.segments)
681 if (S.valno == RHSValNo)
682 Updater.add(S.start, S.end, LHSValNo);
685 /// MergeValueNumberInto - This method is called when two value nubmers
686 /// are found to be equivalent. This eliminates V1, replacing all
687 /// segments with the V1 value number with the V2 value number. This can
688 /// cause merging of V1/V2 values numbers and compaction of the value space.
689 VNInfo *LiveRange::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) {
690 assert(V1 != V2 && "Identical value#'s are always equivalent!");
692 // This code actually merges the (numerically) larger value number into the
693 // smaller value number, which is likely to allow us to compactify the value
694 // space. The only thing we have to be careful of is to preserve the
695 // instruction that defines the result value.
697 // Make sure V2 is smaller than V1.
698 if (V1->id < V2->id) {
703 // Merge V1 segments into V2.
704 for (iterator I = begin(); I != end(); ) {
706 if (S->valno != V1) continue; // Not a V1 Segment.
708 // Okay, we found a V1 live range. If it had a previous, touching, V2 live
712 if (Prev->valno == V2 && Prev->end == S->start) {
715 // Erase this live-range.
722 // Okay, now we have a V1 or V2 live range that is maximally merged forward.
723 // Ensure that it is a V2 live-range.
726 // If we can merge it into later V2 segments, do so now. We ignore any
727 // following V1 segments, as they will be merged in subsequent iterations
730 if (I->start == S->end && I->valno == V2) {
738 // Now that V1 is dead, remove it.
739 markValNoForDeletion(V1);
744 void LiveRange::flushSegmentSet() {
745 assert(segmentSet != nullptr && "segment set must have been created");
748 "segment set can be used only initially before switching to the array");
749 segments.append(segmentSet->begin(), segmentSet->end());
750 segmentSet = nullptr;
754 bool LiveRange::isLiveAtIndexes(ArrayRef<SlotIndex> Slots) const {
755 ArrayRef<SlotIndex>::iterator SlotI = Slots.begin();
756 ArrayRef<SlotIndex>::iterator SlotE = Slots.end();
758 // If there are no regmask slots, we have nothing to search.
762 // Start our search at the first segment that ends after the first slot.
763 const_iterator SegmentI = find(*SlotI);
764 const_iterator SegmentE = end();
766 // If there are no segments that end after the first slot, we're done.
767 if (SegmentI == SegmentE)
770 // Look for each slot in the live range.
771 for ( ; SlotI != SlotE; ++SlotI) {
772 // Go to the next segment that ends after the current slot.
773 // The slot may be within a hole in the range.
774 SegmentI = advanceTo(SegmentI, *SlotI);
775 if (SegmentI == SegmentE)
778 // If this segment contains the slot, we're done.
779 if (SegmentI->contains(*SlotI))
781 // Otherwise, look for the next slot.
784 // We didn't find a segment containing any of the slots.
788 void LiveInterval::freeSubRange(SubRange *S) {
790 // Memory was allocated with BumpPtr allocator and is not freed here.
793 void LiveInterval::removeEmptySubRanges() {
794 SubRange **NextPtr = &SubRanges;
795 SubRange *I = *NextPtr;
796 while (I != nullptr) {
802 // Skip empty subranges until we find the first nonempty one.
804 SubRange *Next = I->Next;
807 } while (I != nullptr && I->empty());
812 void LiveInterval::clearSubRanges() {
813 for (SubRange *I = SubRanges, *Next; I != nullptr; I = Next) {
820 unsigned LiveInterval::getSize() const {
822 for (const Segment &S : segments)
823 Sum += S.start.distance(S.end);
827 raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange::Segment &S) {
828 return os << '[' << S.start << ',' << S.end << ':' << S.valno->id << ')';
831 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
832 LLVM_DUMP_METHOD void LiveRange::Segment::dump() const {
833 dbgs() << *this << '\n';
837 void LiveRange::print(raw_ostream &OS) const {
841 for (const Segment &S : segments) {
843 assert(S.valno == getValNumInfo(S.valno->id) && "Bad VNInfo");
847 // Print value number info.
848 if (getNumValNums()) {
851 for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e;
853 const VNInfo *vni = *i;
856 if (vni->isUnused()) {
867 void LiveInterval::SubRange::print(raw_ostream &OS) const {
868 OS << " L" << PrintLaneMask(LaneMask) << ' '
869 << static_cast<const LiveRange&>(*this);
872 void LiveInterval::print(raw_ostream &OS) const {
873 OS << PrintReg(reg) << ' ';
876 for (const SubRange &SR : subranges())
880 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
881 LLVM_DUMP_METHOD void LiveRange::dump() const {
882 dbgs() << *this << '\n';
885 LLVM_DUMP_METHOD void LiveInterval::SubRange::dump() const {
886 dbgs() << *this << '\n';
889 LLVM_DUMP_METHOD void LiveInterval::dump() const {
890 dbgs() << *this << '\n';
895 void LiveRange::verify() const {
896 for (const_iterator I = begin(), E = end(); I != E; ++I) {
897 assert(I->start.isValid());
898 assert(I->end.isValid());
899 assert(I->start < I->end);
900 assert(I->valno != nullptr);
901 assert(I->valno->id < valnos.size());
902 assert(I->valno == valnos[I->valno->id]);
903 if (std::next(I) != E) {
904 assert(I->end <= std::next(I)->start);
905 if (I->end == std::next(I)->start)
906 assert(I->valno != std::next(I)->valno);
911 void LiveInterval::verify(const MachineRegisterInfo *MRI) const {
914 // Make sure SubRanges are fine and LaneMasks are disjunct.
915 LaneBitmask Mask = 0;
916 LaneBitmask MaxMask = MRI != nullptr ? MRI->getMaxLaneMaskForVReg(reg) : ~0u;
917 for (const SubRange &SR : subranges()) {
918 // Subrange lanemask should be disjunct to any previous subrange masks.
919 assert((Mask & SR.LaneMask) == 0);
922 // subrange mask should not contained in maximum lane mask for the vreg.
923 assert((Mask & ~MaxMask) == 0);
924 // empty subranges must be removed.
928 // Main liverange should cover subrange.
935 //===----------------------------------------------------------------------===//
936 // LiveRangeUpdater class
937 //===----------------------------------------------------------------------===//
939 // The LiveRangeUpdater class always maintains these invariants:
941 // - When LastStart is invalid, Spills is empty and the iterators are invalid.
942 // This is the initial state, and the state created by flush().
943 // In this state, isDirty() returns false.
945 // Otherwise, segments are kept in three separate areas:
947 // 1. [begin; WriteI) at the front of LR.
948 // 2. [ReadI; end) at the back of LR.
951 // - LR.begin() <= WriteI <= ReadI <= LR.end().
952 // - Segments in all three areas are fully ordered and coalesced.
953 // - Segments in area 1 precede and can't coalesce with segments in area 2.
954 // - Segments in Spills precede and can't coalesce with segments in area 2.
955 // - No coalescing is possible between segments in Spills and segments in area
956 // 1, and there are no overlapping segments.
958 // The segments in Spills are not ordered with respect to the segments in area
959 // 1. They need to be merged.
961 // When they exist, Spills.back().start <= LastStart,
962 // and WriteI[-1].start <= LastStart.
964 void LiveRangeUpdater::print(raw_ostream &OS) const {
967 OS << "Clean updater: " << *LR << '\n';
969 OS << "Null updater.\n";
972 assert(LR && "Can't have null LR in dirty updater.");
973 OS << " updater with gap = " << (ReadI - WriteI)
974 << ", last start = " << LastStart
976 for (const auto &S : make_range(LR->begin(), WriteI))
979 for (unsigned I = 0, E = Spills.size(); I != E; ++I)
980 OS << ' ' << Spills[I];
982 for (const auto &S : make_range(ReadI, LR->end()))
987 LLVM_DUMP_METHOD void LiveRangeUpdater::dump() const {
991 // Determine if A and B should be coalesced.
992 static inline bool coalescable(const LiveRange::Segment &A,
993 const LiveRange::Segment &B) {
994 assert(A.start <= B.start && "Unordered live segments.");
995 if (A.end == B.start)
996 return A.valno == B.valno;
999 assert(A.valno == B.valno && "Cannot overlap different values");
1003 void LiveRangeUpdater::add(LiveRange::Segment Seg) {
1004 assert(LR && "Cannot add to a null destination");
1006 // Fall back to the regular add method if the live range
1007 // is using the segment set instead of the segment vector.
1008 if (LR->segmentSet != nullptr) {
1009 LR->addSegmentToSet(Seg);
1013 // Flush the state if Start moves backwards.
1014 if (!LastStart.isValid() || LastStart > Seg.start) {
1017 // This brings us to an uninitialized state. Reinitialize.
1018 assert(Spills.empty() && "Leftover spilled segments");
1019 WriteI = ReadI = LR->begin();
1022 // Remember start for next time.
1023 LastStart = Seg.start;
1025 // Advance ReadI until it ends after Seg.start.
1026 LiveRange::iterator E = LR->end();
1027 if (ReadI != E && ReadI->end <= Seg.start) {
1028 // First try to close the gap between WriteI and ReadI with spills.
1029 if (ReadI != WriteI)
1031 // Then advance ReadI.
1032 if (ReadI == WriteI)
1033 ReadI = WriteI = LR->find(Seg.start);
1035 while (ReadI != E && ReadI->end <= Seg.start)
1036 *WriteI++ = *ReadI++;
1039 assert(ReadI == E || ReadI->end > Seg.start);
1041 // Check if the ReadI segment begins early.
1042 if (ReadI != E && ReadI->start <= Seg.start) {
1043 assert(ReadI->valno == Seg.valno && "Cannot overlap different values");
1044 // Bail if Seg is completely contained in ReadI.
1045 if (ReadI->end >= Seg.end)
1047 // Coalesce into Seg.
1048 Seg.start = ReadI->start;
1052 // Coalesce as much as possible from ReadI into Seg.
1053 while (ReadI != E && coalescable(Seg, *ReadI)) {
1054 Seg.end = std::max(Seg.end, ReadI->end);
1058 // Try coalescing Spills.back() into Seg.
1059 if (!Spills.empty() && coalescable(Spills.back(), Seg)) {
1060 Seg.start = Spills.back().start;
1061 Seg.end = std::max(Spills.back().end, Seg.end);
1065 // Try coalescing Seg into WriteI[-1].
1066 if (WriteI != LR->begin() && coalescable(WriteI[-1], Seg)) {
1067 WriteI[-1].end = std::max(WriteI[-1].end, Seg.end);
1071 // Seg doesn't coalesce with anything, and needs to be inserted somewhere.
1072 if (WriteI != ReadI) {
1077 // Finally, append to LR or Spills.
1079 LR->segments.push_back(Seg);
1080 WriteI = ReadI = LR->end();
1082 Spills.push_back(Seg);
1085 // Merge as many spilled segments as possible into the gap between WriteI
1086 // and ReadI. Advance WriteI to reflect the inserted instructions.
1087 void LiveRangeUpdater::mergeSpills() {
1088 // Perform a backwards merge of Spills and [SpillI;WriteI).
1089 size_t GapSize = ReadI - WriteI;
1090 size_t NumMoved = std::min(Spills.size(), GapSize);
1091 LiveRange::iterator Src = WriteI;
1092 LiveRange::iterator Dst = Src + NumMoved;
1093 LiveRange::iterator SpillSrc = Spills.end();
1094 LiveRange::iterator B = LR->begin();
1096 // This is the new WriteI position after merging spills.
1099 // Now merge Src and Spills backwards.
1100 while (Src != Dst) {
1101 if (Src != B && Src[-1].start > SpillSrc[-1].start)
1104 *--Dst = *--SpillSrc;
1106 assert(NumMoved == size_t(Spills.end() - SpillSrc));
1107 Spills.erase(SpillSrc, Spills.end());
1110 void LiveRangeUpdater::flush() {
1113 // Clear the dirty state.
1114 LastStart = SlotIndex();
1116 assert(LR && "Cannot add to a null destination");
1118 // Nothing to merge?
1119 if (Spills.empty()) {
1120 LR->segments.erase(WriteI, ReadI);
1125 // Resize the WriteI - ReadI gap to match Spills.
1126 size_t GapSize = ReadI - WriteI;
1127 if (GapSize < Spills.size()) {
1128 // The gap is too small. Make some room.
1129 size_t WritePos = WriteI - LR->begin();
1130 LR->segments.insert(ReadI, Spills.size() - GapSize, LiveRange::Segment());
1131 // This also invalidated ReadI, but it is recomputed below.
1132 WriteI = LR->begin() + WritePos;
1134 // Shrink the gap if necessary.
1135 LR->segments.erase(WriteI + Spills.size(), ReadI);
1137 ReadI = WriteI + Spills.size();
1142 unsigned ConnectedVNInfoEqClasses::Classify(const LiveRange &LR) {
1143 // Create initial equivalence classes.
1145 EqClass.grow(LR.getNumValNums());
1147 const VNInfo *used = nullptr, *unused = nullptr;
1149 // Determine connections.
1150 for (const VNInfo *VNI : LR.valnos) {
1151 // Group all unused values into one class.
1152 if (VNI->isUnused()) {
1154 EqClass.join(unused->id, VNI->id);
1159 if (VNI->isPHIDef()) {
1160 const MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def);
1161 assert(MBB && "Phi-def has no defining MBB");
1162 // Connect to values live out of predecessors.
1163 for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
1164 PE = MBB->pred_end(); PI != PE; ++PI)
1165 if (const VNInfo *PVNI = LR.getVNInfoBefore(LIS.getMBBEndIdx(*PI)))
1166 EqClass.join(VNI->id, PVNI->id);
1168 // Normal value defined by an instruction. Check for two-addr redef.
1169 // FIXME: This could be coincidental. Should we really check for a tied
1170 // operand constraint?
1171 // Note that VNI->def may be a use slot for an early clobber def.
1172 if (const VNInfo *UVNI = LR.getVNInfoBefore(VNI->def))
1173 EqClass.join(VNI->id, UVNI->id);
1177 // Lump all the unused values in with the last used value.
1179 EqClass.join(used->id, unused->id);
1182 return EqClass.getNumClasses();
1185 void ConnectedVNInfoEqClasses::Distribute(LiveInterval &LI, LiveInterval *LIV[],
1186 MachineRegisterInfo &MRI) {
1187 // Rewrite instructions.
1188 for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg),
1189 RE = MRI.reg_end(); RI != RE;) {
1190 MachineOperand &MO = *RI;
1191 MachineInstr *MI = RI->getParent();
1193 // DBG_VALUE instructions don't have slot indexes, so get the index of the
1194 // instruction before them.
1195 // Normally, DBG_VALUE instructions are removed before this function is
1196 // called, but it is not a requirement.
1198 if (MI->isDebugValue())
1199 Idx = LIS.getSlotIndexes()->getIndexBefore(*MI);
1201 Idx = LIS.getInstructionIndex(*MI);
1202 LiveQueryResult LRQ = LI.Query(Idx);
1203 const VNInfo *VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined();
1204 // In the case of an <undef> use that isn't tied to any def, VNI will be
1205 // NULL. If the use is tied to a def, VNI will be the defined value.
1208 if (unsigned EqClass = getEqClass(VNI))
1209 MO.setReg(LIV[EqClass-1]->reg);
1212 // Distribute subregister liveranges.
1213 if (LI.hasSubRanges()) {
1214 unsigned NumComponents = EqClass.getNumClasses();
1215 SmallVector<unsigned, 8> VNIMapping;
1216 SmallVector<LiveInterval::SubRange*, 8> SubRanges;
1217 BumpPtrAllocator &Allocator = LIS.getVNInfoAllocator();
1218 for (LiveInterval::SubRange &SR : LI.subranges()) {
1219 // Create new subranges in the split intervals and construct a mapping
1220 // for the VNInfos in the subrange.
1221 unsigned NumValNos = SR.valnos.size();
1223 VNIMapping.reserve(NumValNos);
1225 SubRanges.resize(NumComponents-1, nullptr);
1226 for (unsigned I = 0; I < NumValNos; ++I) {
1227 const VNInfo &VNI = *SR.valnos[I];
1228 unsigned ComponentNum;
1229 if (VNI.isUnused()) {
1232 const VNInfo *MainRangeVNI = LI.getVNInfoAt(VNI.def);
1233 assert(MainRangeVNI != nullptr
1234 && "SubRange def must have corresponding main range def");
1235 ComponentNum = getEqClass(MainRangeVNI);
1236 if (ComponentNum > 0 && SubRanges[ComponentNum-1] == nullptr) {
1237 SubRanges[ComponentNum-1]
1238 = LIV[ComponentNum-1]->createSubRange(Allocator, SR.LaneMask);
1241 VNIMapping.push_back(ComponentNum);
1243 DistributeRange(SR, SubRanges.data(), VNIMapping);
1245 LI.removeEmptySubRanges();
1248 // Distribute main liverange.
1249 DistributeRange(LI, LIV, EqClass);