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 interval 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 intervals can have holes,
15 // i.e. an interval might look like [1,20), [50,65), [1000,1001). Each
16 // individual range is represented as an instance of LiveRange, and the whole
17 // interval is represented as an instance of LiveInterval.
19 //===----------------------------------------------------------------------===//
21 #include "llvm/CodeGen/LiveInterval.h"
22 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 #include "llvm/ADT/DenseMap.h"
25 #include "llvm/ADT/SmallSet.h"
26 #include "llvm/ADT/STLExtras.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Target/TargetRegisterInfo.h"
33 LiveInterval::iterator LiveInterval::find(SlotIndex Pos) {
34 // This algorithm is basically std::upper_bound.
35 // Unfortunately, std::upper_bound cannot be used with mixed types until we
36 // adopt C++0x. Many libraries can do it, but not all.
37 if (empty() || Pos >= endIndex())
40 size_t Len = ranges.size();
42 size_t Mid = Len >> 1;
46 I += Mid + 1, Len -= Mid + 1;
51 VNInfo *LiveInterval::createDeadDef(SlotIndex Def,
52 VNInfo::Allocator &VNInfoAllocator) {
53 assert(!Def.isDead() && "Cannot define a value at the dead slot");
54 iterator I = find(Def);
56 VNInfo *VNI = getNextValue(Def, VNInfoAllocator);
57 ranges.push_back(LiveRange(Def, Def.getDeadSlot(), VNI));
60 if (SlotIndex::isSameInstr(Def, I->start)) {
61 assert(I->start == Def && "Cannot insert def, already live");
62 assert(I->valno->def == Def && "Inconsistent existing value def");
65 assert(SlotIndex::isEarlierInstr(Def, I->start) && "Already live at def");
66 VNInfo *VNI = getNextValue(Def, VNInfoAllocator);
67 ranges.insert(I, LiveRange(Def, Def.getDeadSlot(), VNI));
71 /// killedInRange - Return true if the interval has kills in [Start,End).
72 bool LiveInterval::killedInRange(SlotIndex Start, SlotIndex End) const {
73 Ranges::const_iterator r =
74 std::lower_bound(ranges.begin(), ranges.end(), End);
76 // Now r points to the first interval with start >= End, or ranges.end().
77 if (r == ranges.begin())
81 // Now r points to the last interval with end <= End.
82 // r->end is the kill point.
83 return r->end >= Start && r->end < End;
86 // overlaps - Return true if the intersection of the two live intervals is
89 // An example for overlaps():
93 // 8: C = A + B ;; last use of A
95 // The live intervals should look like:
101 // A->overlaps(C) should return false since we want to be able to join
104 bool LiveInterval::overlapsFrom(const LiveInterval& other,
105 const_iterator StartPos) const {
106 assert(!empty() && "empty interval");
107 const_iterator i = begin();
108 const_iterator ie = end();
109 const_iterator j = StartPos;
110 const_iterator je = other.end();
112 assert((StartPos->start <= i->start || StartPos == other.begin()) &&
113 StartPos != other.end() && "Bogus start position hint!");
115 if (i->start < j->start) {
116 i = std::upper_bound(i, ie, j->start);
117 if (i != ranges.begin()) --i;
118 } else if (j->start < i->start) {
120 if (StartPos != other.end() && StartPos->start <= i->start) {
121 assert(StartPos < other.end() && i < end());
122 j = std::upper_bound(j, je, i->start);
123 if (j != other.ranges.begin()) --j;
129 if (j == je) return false;
132 if (i->start > j->start) {
137 if (i->end > j->start)
145 /// overlaps - Return true if the live interval overlaps a range specified
147 bool LiveInterval::overlaps(SlotIndex Start, SlotIndex End) const {
148 assert(Start < End && "Invalid range");
149 const_iterator I = std::lower_bound(begin(), end(), End);
150 return I != begin() && (--I)->end > Start;
154 /// ValNo is dead, remove it. If it is the largest value number, just nuke it
155 /// (and any other deleted values neighboring it), otherwise mark it as ~1U so
156 /// it can be nuked later.
157 void LiveInterval::markValNoForDeletion(VNInfo *ValNo) {
158 if (ValNo->id == getNumValNums()-1) {
161 } while (!valnos.empty() && valnos.back()->isUnused());
167 /// RenumberValues - Renumber all values in order of appearance and delete the
168 /// remaining unused values.
169 void LiveInterval::RenumberValues(LiveIntervals &lis) {
170 SmallPtrSet<VNInfo*, 8> Seen;
172 for (const_iterator I = begin(), E = end(); I != E; ++I) {
173 VNInfo *VNI = I->valno;
174 if (!Seen.insert(VNI))
176 assert(!VNI->isUnused() && "Unused valno used by live range");
177 VNI->id = (unsigned)valnos.size();
178 valnos.push_back(VNI);
182 /// extendIntervalEndTo - This method is used when we want to extend the range
183 /// specified by I to end at the specified endpoint. To do this, we should
184 /// merge and eliminate all ranges that this will overlap with. The iterator is
186 void LiveInterval::extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd) {
187 assert(I != ranges.end() && "Not a valid interval!");
188 VNInfo *ValNo = I->valno;
190 // Search for the first interval that we can't merge with.
191 Ranges::iterator MergeTo = llvm::next(I);
192 for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo) {
193 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
196 // If NewEnd was in the middle of an interval, make sure to get its endpoint.
197 I->end = std::max(NewEnd, prior(MergeTo)->end);
199 // If the newly formed range now touches the range after it and if they have
200 // the same value number, merge the two ranges into one range.
201 if (MergeTo != ranges.end() && MergeTo->start <= I->end &&
202 MergeTo->valno == ValNo) {
203 I->end = MergeTo->end;
207 // Erase any dead ranges.
208 ranges.erase(llvm::next(I), MergeTo);
212 /// extendIntervalStartTo - This method is used when we want to extend the range
213 /// specified by I to start at the specified endpoint. To do this, we should
214 /// merge and eliminate all ranges that this will overlap with.
215 LiveInterval::Ranges::iterator
216 LiveInterval::extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStart) {
217 assert(I != ranges.end() && "Not a valid interval!");
218 VNInfo *ValNo = I->valno;
220 // Search for the first interval that we can't merge with.
221 Ranges::iterator MergeTo = I;
223 if (MergeTo == ranges.begin()) {
225 ranges.erase(MergeTo, I);
228 assert(MergeTo->valno == ValNo && "Cannot merge with differing values!");
230 } while (NewStart <= MergeTo->start);
232 // If we start in the middle of another interval, just delete a range and
233 // extend that interval.
234 if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) {
235 MergeTo->end = I->end;
237 // Otherwise, extend the interval right after.
239 MergeTo->start = NewStart;
240 MergeTo->end = I->end;
243 ranges.erase(llvm::next(MergeTo), llvm::next(I));
247 LiveInterval::iterator
248 LiveInterval::addRangeFrom(LiveRange LR, iterator From) {
249 SlotIndex Start = LR.start, End = LR.end;
250 iterator it = std::upper_bound(From, ranges.end(), Start);
252 // If the inserted interval starts in the middle or right at the end of
253 // another interval, just extend that interval to contain the range of LR.
254 if (it != ranges.begin()) {
255 iterator B = prior(it);
256 if (LR.valno == B->valno) {
257 if (B->start <= Start && B->end >= Start) {
258 extendIntervalEndTo(B, End);
262 // Check to make sure that we are not overlapping two live ranges with
263 // different valno's.
264 assert(B->end <= Start &&
265 "Cannot overlap two LiveRanges with differing ValID's"
266 " (did you def the same reg twice in a MachineInstr?)");
270 // Otherwise, if this range ends in the middle of, or right next to, another
271 // interval, merge it into that interval.
272 if (it != ranges.end()) {
273 if (LR.valno == it->valno) {
274 if (it->start <= End) {
275 it = extendIntervalStartTo(it, Start);
277 // If LR is a complete superset of an interval, we may need to grow its
280 extendIntervalEndTo(it, End);
284 // Check to make sure that we are not overlapping two live ranges with
285 // different valno's.
286 assert(it->start >= End &&
287 "Cannot overlap two LiveRanges with differing ValID's");
291 // Otherwise, this is just a new range that doesn't interact with anything.
293 return ranges.insert(it, LR);
296 /// extendInBlock - If this interval is live before Kill in the basic
297 /// block that starts at StartIdx, extend it to be live up to Kill and return
298 /// the value. If there is no live range before Kill, return NULL.
299 VNInfo *LiveInterval::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) {
302 iterator I = std::upper_bound(begin(), end(), Kill.getPrevSlot());
306 if (I->end <= StartIdx)
309 extendIntervalEndTo(I, Kill);
313 /// removeRange - Remove the specified range from this interval. Note that
314 /// the range must be in a single LiveRange in its entirety.
315 void LiveInterval::removeRange(SlotIndex Start, SlotIndex End,
316 bool RemoveDeadValNo) {
317 // Find the LiveRange containing this span.
318 Ranges::iterator I = find(Start);
319 assert(I != ranges.end() && "Range is not in interval!");
320 assert(I->containsRange(Start, End) && "Range is not entirely in interval!");
322 // If the span we are removing is at the start of the LiveRange, adjust it.
323 VNInfo *ValNo = I->valno;
324 if (I->start == Start) {
326 if (RemoveDeadValNo) {
327 // Check if val# is dead.
329 for (const_iterator II = begin(), EE = end(); II != EE; ++II)
330 if (II != I && II->valno == ValNo) {
335 // Now that ValNo is dead, remove it.
336 markValNoForDeletion(ValNo);
340 ranges.erase(I); // Removed the whole LiveRange.
346 // Otherwise if the span we are removing is at the end of the LiveRange,
347 // adjust the other way.
353 // Otherwise, we are splitting the LiveRange into two pieces.
354 SlotIndex OldEnd = I->end;
355 I->end = Start; // Trim the old interval.
357 // Insert the new one.
358 ranges.insert(llvm::next(I), LiveRange(End, OldEnd, ValNo));
361 /// removeValNo - Remove all the ranges defined by the specified value#.
362 /// Also remove the value# from value# list.
363 void LiveInterval::removeValNo(VNInfo *ValNo) {
365 Ranges::iterator I = ranges.end();
366 Ranges::iterator E = ranges.begin();
369 if (I->valno == ValNo)
372 // Now that ValNo is dead, remove it.
373 markValNoForDeletion(ValNo);
376 /// join - Join two live intervals (this, and other) together. This applies
377 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
378 /// the intervals are not joinable, this aborts.
379 void LiveInterval::join(LiveInterval &Other,
380 const int *LHSValNoAssignments,
381 const int *RHSValNoAssignments,
382 SmallVector<VNInfo*, 16> &NewVNInfo,
383 MachineRegisterInfo *MRI) {
386 // Determine if any of our live range values are mapped. This is uncommon, so
387 // we want to avoid the interval scan if not.
388 bool MustMapCurValNos = false;
389 unsigned NumVals = getNumValNums();
390 unsigned NumNewVals = NewVNInfo.size();
391 for (unsigned i = 0; i != NumVals; ++i) {
392 unsigned LHSValID = LHSValNoAssignments[i];
394 (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i))) {
395 MustMapCurValNos = true;
400 // If we have to apply a mapping to our base interval assignment, rewrite it
402 if (MustMapCurValNos) {
403 // Map the first live range.
405 iterator OutIt = begin();
406 OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]];
407 for (iterator I = next(OutIt), E = end(); I != E; ++I) {
408 VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]];
409 assert(nextValNo != 0 && "Huh?");
411 // If this live range has the same value # as its immediate predecessor,
412 // and if they are neighbors, remove one LiveRange. This happens when we
413 // have [0,4:0)[4,7:1) and map 0/1 onto the same value #.
414 if (OutIt->valno == nextValNo && OutIt->end == I->start) {
417 // Didn't merge. Move OutIt to the next interval,
419 OutIt->valno = nextValNo;
421 OutIt->start = I->start;
426 // If we merge some live ranges, chop off the end.
428 ranges.erase(OutIt, end());
431 // Remember assignements because val# ids are changing.
432 SmallVector<unsigned, 16> OtherAssignments;
433 for (iterator I = Other.begin(), E = Other.end(); I != E; ++I)
434 OtherAssignments.push_back(RHSValNoAssignments[I->valno->id]);
436 // Update val# info. Renumber them and make sure they all belong to this
437 // LiveInterval now. Also remove dead val#'s.
438 unsigned NumValNos = 0;
439 for (unsigned i = 0; i < NumNewVals; ++i) {
440 VNInfo *VNI = NewVNInfo[i];
442 if (NumValNos >= NumVals)
443 valnos.push_back(VNI);
445 valnos[NumValNos] = VNI;
446 VNI->id = NumValNos++; // Renumber val#.
449 if (NumNewVals < NumVals)
450 valnos.resize(NumNewVals); // shrinkify
452 // Okay, now insert the RHS live ranges into the LHS.
453 unsigned RangeNo = 0;
454 for (iterator I = Other.begin(), E = Other.end(); I != E; ++I, ++RangeNo) {
455 // Map the valno in the other live range to the current live range.
456 I->valno = NewVNInfo[OtherAssignments[RangeNo]];
457 assert(I->valno && "Adding a dead range?");
459 mergeIntervalRanges(Other);
464 /// \brief Helper function for merging in another LiveInterval's ranges.
466 /// This is a helper routine implementing an efficient merge of another
467 /// LiveIntervals ranges into the current interval.
469 /// \param LHSValNo If non-NULL, set as the new value number for every range
470 /// from RHS which is merged into the LHS.
471 /// \param RHSValNo If non-NULL, then only ranges in RHS whose original value
472 /// number maches this value number will be merged into LHS.
473 void LiveInterval::mergeIntervalRanges(const LiveInterval &RHS,
475 const VNInfo *RHSValNo) {
479 // Ensure we're starting with a valid range. Note that we don't verify RHS
480 // because it may have had its value numbers adjusted in preparation for
484 // The strategy for merging these efficiently is as follows:
486 // 1) Find the beginning of the impacted ranges in the LHS.
487 // 2) Create a new, merged sub-squence of ranges merging from the position in
488 // #1 until either LHS or RHS is exhausted. Any part of LHS between RHS
489 // entries being merged will be copied into this new range.
490 // 3) Replace the relevant section in LHS with these newly merged ranges.
491 // 4) Append any remaning ranges from RHS if LHS is exhausted in #2.
493 // We don't follow the typical in-place merge strategy for sorted ranges of
494 // appending the new ranges to the back and then using std::inplace_merge
495 // because one step of the merge can both mutate the original elements and
496 // remove elements from the original. Essentially, because the merge includes
497 // collapsing overlapping ranges, a more complex approach is required.
499 // We do an initial binary search to optimize for a common pattern: a large
500 // LHS, and a very small RHS.
501 const_iterator RI = RHS.begin(), RE = RHS.end();
502 iterator LE = end(), LI = std::upper_bound(begin(), LE, *RI);
504 // Merge into NewRanges until one of the ranges is exhausted.
505 SmallVector<LiveRange, 4> NewRanges;
507 // Keep track of where to begin the replacement.
508 iterator ReplaceI = LI;
510 // If there are preceding ranges in the LHS, put the last one into NewRanges
511 // so we can optionally extend it. Adjust the replacement point accordingly.
513 ReplaceI = llvm::prior(LI);
514 NewRanges.push_back(*ReplaceI);
517 // Now loop over the mergable portions of both LHS and RHS, merging into
519 while (LI != LE && RI != RE) {
520 // Skip incoming ranges with the wrong value.
521 if (RHSValNo && RI->valno != RHSValNo) {
526 // Select the first range. We pick the earliest start point, and then the
538 if (NewRanges.empty()) {
539 NewRanges.push_back(R);
543 LiveRange &LastR = NewRanges.back();
544 if (R.valno == LastR.valno) {
545 // Try to merge this range into the last one.
546 if (R.start <= LastR.end) {
547 LastR.end = std::max(LastR.end, R.end);
551 // We can't merge ranges across a value number.
552 assert(R.start >= LastR.end &&
553 "Cannot overlap two LiveRanges with differing ValID's");
556 // If all else fails, just append the range.
557 NewRanges.push_back(R);
559 assert(RI == RE || LI == LE);
561 // Check for being able to merge into the trailing sequence of ranges on the LHS.
562 if (!NewRanges.empty())
563 for (; LI != LE && (LI->valno == NewRanges.back().valno &&
564 LI->start <= NewRanges.back().end);
566 NewRanges.back().end = std::max(NewRanges.back().end, LI->end);
568 // Replace the ranges in the LHS with the newly merged ones. It would be
569 // really nice if there were a move-supporting 'replace' directly in
570 // SmallVector, but as there is not, we pay the price of copies to avoid
571 // wasted memory allocations.
572 SmallVectorImpl<LiveRange>::iterator NRI = NewRanges.begin(),
573 NRE = NewRanges.end();
574 for (; ReplaceI != LI && NRI != NRE; ++ReplaceI, ++NRI)
577 ranges.erase(ReplaceI, LI);
579 ranges.insert(LI, NRI, NRE);
581 // And finally insert any trailing end of RHS (if we have one).
582 for (; RI != RE; ++RI) {
586 if (!ranges.empty() &&
587 ranges.back().valno == R.valno && R.start <= ranges.back().end)
588 ranges.back().end = std::max(ranges.back().end, R.end);
593 // Ensure we finished with a valid new sequence of ranges.
597 /// MergeRangesInAsValue - Merge all of the intervals in RHS into this live
598 /// interval as the specified value number. The LiveRanges in RHS are
599 /// allowed to overlap with LiveRanges in the current interval, but only if
600 /// the overlapping LiveRanges have the specified value number.
601 void LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS,
603 mergeIntervalRanges(RHS, LHSValNo);
606 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
607 /// in RHS into this live interval as the specified value number.
608 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
609 /// current interval, it will replace the value numbers of the overlaped
610 /// live ranges with the specified value number.
611 void LiveInterval::MergeValueInAsValue(const LiveInterval &RHS,
612 const VNInfo *RHSValNo,
614 mergeIntervalRanges(RHS, LHSValNo, RHSValNo);
617 /// MergeValueNumberInto - This method is called when two value nubmers
618 /// are found to be equivalent. This eliminates V1, replacing all
619 /// LiveRanges with the V1 value number with the V2 value number. This can
620 /// cause merging of V1/V2 values numbers and compaction of the value space.
621 VNInfo* LiveInterval::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) {
622 assert(V1 != V2 && "Identical value#'s are always equivalent!");
624 // This code actually merges the (numerically) larger value number into the
625 // smaller value number, which is likely to allow us to compactify the value
626 // space. The only thing we have to be careful of is to preserve the
627 // instruction that defines the result value.
629 // Make sure V2 is smaller than V1.
630 if (V1->id < V2->id) {
635 // Merge V1 live ranges into V2.
636 for (iterator I = begin(); I != end(); ) {
638 if (LR->valno != V1) continue; // Not a V1 LiveRange.
640 // Okay, we found a V1 live range. If it had a previous, touching, V2 live
643 iterator Prev = LR-1;
644 if (Prev->valno == V2 && Prev->end == LR->start) {
647 // Erase this live-range.
654 // Okay, now we have a V1 or V2 live range that is maximally merged forward.
655 // Ensure that it is a V2 live-range.
658 // If we can merge it into later V2 live ranges, do so now. We ignore any
659 // following V1 live ranges, as they will be merged in subsequent iterations
662 if (I->start == LR->end && I->valno == V2) {
670 // Now that V1 is dead, remove it.
671 markValNoForDeletion(V1);
676 void LiveInterval::Copy(const LiveInterval &RHS,
677 MachineRegisterInfo *MRI,
678 VNInfo::Allocator &VNInfoAllocator) {
681 std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(RHS.reg);
682 MRI->setRegAllocationHint(reg, Hint.first, Hint.second);
685 for (unsigned i = 0, e = RHS.getNumValNums(); i != e; ++i) {
686 const VNInfo *VNI = RHS.getValNumInfo(i);
687 createValueCopy(VNI, VNInfoAllocator);
689 for (unsigned i = 0, e = RHS.ranges.size(); i != e; ++i) {
690 const LiveRange &LR = RHS.ranges[i];
691 addRange(LiveRange(LR.start, LR.end, getValNumInfo(LR.valno->id)));
697 unsigned LiveInterval::getSize() const {
699 for (const_iterator I = begin(), E = end(); I != E; ++I)
700 Sum += I->start.distance(I->end);
704 raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange &LR) {
705 return os << '[' << LR.start << ',' << LR.end << ':' << LR.valno->id << ")";
708 void LiveRange::dump() const {
709 dbgs() << *this << "\n";
712 void LiveInterval::print(raw_ostream &OS) const {
716 for (LiveInterval::Ranges::const_iterator I = ranges.begin(),
717 E = ranges.end(); I != E; ++I) {
719 assert(I->valno == getValNumInfo(I->valno->id) && "Bad VNInfo");
723 // Print value number info.
724 if (getNumValNums()) {
727 for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e;
729 const VNInfo *vni = *i;
732 if (vni->isUnused()) {
743 void LiveInterval::dump() const {
744 dbgs() << *this << "\n";
748 void LiveInterval::verify() const {
749 for (const_iterator I = begin(), E = end(); I != E; ++I) {
750 assert(I->start.isValid());
751 assert(I->end.isValid());
752 assert(I->start < I->end);
753 assert(I->valno != 0);
754 assert(I->valno == valnos[I->valno->id]);
755 if (llvm::next(I) != E) {
756 assert(I->end <= llvm::next(I)->start);
757 if (I->end == llvm::next(I)->start)
758 assert(I->valno != llvm::next(I)->valno);
765 void LiveRange::print(raw_ostream &os) const {
769 unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
770 // Create initial equivalence classes.
772 EqClass.grow(LI->getNumValNums());
774 const VNInfo *used = 0, *unused = 0;
776 // Determine connections.
777 for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end();
779 const VNInfo *VNI = *I;
780 // Group all unused values into one class.
781 if (VNI->isUnused()) {
783 EqClass.join(unused->id, VNI->id);
788 if (VNI->isPHIDef()) {
789 const MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def);
790 assert(MBB && "Phi-def has no defining MBB");
791 // Connect to values live out of predecessors.
792 for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
793 PE = MBB->pred_end(); PI != PE; ++PI)
794 if (const VNInfo *PVNI = LI->getVNInfoBefore(LIS.getMBBEndIdx(*PI)))
795 EqClass.join(VNI->id, PVNI->id);
797 // Normal value defined by an instruction. Check for two-addr redef.
798 // FIXME: This could be coincidental. Should we really check for a tied
799 // operand constraint?
800 // Note that VNI->def may be a use slot for an early clobber def.
801 if (const VNInfo *UVNI = LI->getVNInfoBefore(VNI->def))
802 EqClass.join(VNI->id, UVNI->id);
806 // Lump all the unused values in with the last used value.
808 EqClass.join(used->id, unused->id);
811 return EqClass.getNumClasses();
814 void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[],
815 MachineRegisterInfo &MRI) {
816 assert(LIV[0] && "LIV[0] must be set");
817 LiveInterval &LI = *LIV[0];
819 // Rewrite instructions.
820 for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg),
821 RE = MRI.reg_end(); RI != RE;) {
822 MachineOperand &MO = RI.getOperand();
823 MachineInstr *MI = MO.getParent();
825 // DBG_VALUE instructions should have been eliminated earlier.
826 LiveRangeQuery LRQ(LI, LIS.getInstructionIndex(MI));
827 const VNInfo *VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined();
828 // In the case of an <undef> use that isn't tied to any def, VNI will be
829 // NULL. If the use is tied to a def, VNI will be the defined value.
832 MO.setReg(LIV[getEqClass(VNI)]->reg);
835 // Move runs to new intervals.
836 LiveInterval::iterator J = LI.begin(), E = LI.end();
837 while (J != E && EqClass[J->valno->id] == 0)
839 for (LiveInterval::iterator I = J; I != E; ++I) {
840 if (unsigned eq = EqClass[I->valno->id]) {
841 assert((LIV[eq]->empty() || LIV[eq]->expiredAt(I->start)) &&
842 "New intervals should be empty");
843 LIV[eq]->ranges.push_back(*I);
847 LI.ranges.erase(J, E);
849 // Transfer VNInfos to their new owners and renumber them.
850 unsigned j = 0, e = LI.getNumValNums();
851 while (j != e && EqClass[j] == 0)
853 for (unsigned i = j; i != e; ++i) {
854 VNInfo *VNI = LI.getValNumInfo(i);
855 if (unsigned eq = EqClass[i]) {
856 VNI->id = LIV[eq]->getNumValNums();
857 LIV[eq]->valnos.push_back(VNI);
860 LI.valnos[j++] = VNI;